U.S. patent application number 17/698077 was filed with the patent office on 2022-06-30 for methods and apparatus for respiratory treatment.
This patent application is currently assigned to ResMed Pty Ltd. The applicant listed for this patent is ResMed Pty Ltd. Invention is credited to Liam HOLLEY, Gordon Joseph MALOUF, Dion Charles Chewe MARTIN, Peter WLODARCZYK, Quangang YANG.
Application Number | 20220203058 17/698077 |
Document ID | / |
Family ID | |
Filed Date | 2022-06-30 |
United States Patent
Application |
20220203058 |
Kind Code |
A1 |
HOLLEY; Liam ; et
al. |
June 30, 2022 |
METHODS AND APPARATUS FOR RESPIRATORY TREATMENT
Abstract
Apparatus and methods provide control for generation of a flow
of air to a patient's airways for different respiratory therapies.
The pressure and a flow rate may be simultaneously controlled so as
to provide a pressure therapy and a flow therapy. The system may
include one or more flow generators, in which the control of the
pressure and flow rate may include altering the output of one or
more of the flow generators and/or an optional adjustable vent. The
pressure and flow rate may each be held at a constant. One or both
of the pressure and flow rate may also vary in accordance with a
desired therapy. The air may be provided via a patient interface
that includes a vent to atmosphere, which may be the adjustable
vent. The vent may be actuated by a controller to implement the
simultaneous control of pressure and flow rate of the air.
Inventors: |
HOLLEY; Liam; (Sydney,
AU) ; MALOUF; Gordon Joseph; (Sydney, AU) ;
MARTIN; Dion Charles Chewe; (Sydney, AU) ;
WLODARCZYK; Peter; (Ashfield, AU) ; YANG;
Quangang; (Sydney, AU) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
ResMed Pty Ltd |
Bella Vista |
|
AU |
|
|
Assignee: |
ResMed Pty Ltd
Bella Vista
AU
|
Appl. No.: |
17/698077 |
Filed: |
March 18, 2022 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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15781599 |
Jun 5, 2018 |
11318266 |
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PCT/AU2016/051210 |
Dec 9, 2016 |
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17698077 |
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62265700 |
Dec 10, 2015 |
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International
Class: |
A61M 16/06 20060101
A61M016/06; A61M 16/16 20060101 A61M016/16; A61M 16/00 20060101
A61M016/00 |
Claims
1. A system for delivery of a flow of air to a patient's airways
comprising: a flow generator configured to provide air to a patient
via an air circuit and a patient interface; an adjustable vent; and
one or more controllers configured to: determine a pressure and a
flow rate of the air being provided to the patient via the patient
interface with a plurality of sensors; and control the flow
generator and the adjustable vent so as to simultaneously control
the pressure and the flow rate of the air at the patient interface
to correspond with a predetermined pressure and a predetermined
flow rate, respectively.
2. The system of claim 1 further comprising the patient interface,
wherein the patient interface comprises a projection portion
configured to conduct a flow of the air into a naris of a patient
and a mask portion configured to apply pressure of the air to the
patient.
3. The system of claim 2, wherein the adjustable vent is part of
the mask portion of the patient interface.
4. The system of claim 2, wherein the plurality of sensors
comprise: a pressure sensor for determining a measured pressure of
the air; and a flow rate sensor for determining a measured flow
rate of the air through the projection portion of the patient
interface.
5. The system of claim 4, wherein at least one of the pressure
sensor and the flow rate sensor is located at an output of the flow
generator.
6. The system of claim 4, wherein at least one of the pressure
sensor and the flow rate sensor is located at the patient
interface.
7. The system of claim 1, wherein the one or more controllers are
further configured to maintain at least one of the predetermined
pressure and the predetermined flow rate at a constant value for a
period of time.
8. The system of claim 1, wherein the one or more controllers are
further configured to vary the predetermined pressure in accordance
with a breathing cycle of the patient.
9. The system of claim 1, wherein the simultaneous control of the
pressure and the flow rate of the air provides the patient with a
positive airway pressure therapy and a deadspace therapy.
10. The system of claim 9, wherein the positive airway pressure
therapy is a ventilation therapy.
11. The system of claim 1, wherein the one or more controllers are
configured to determine the predetermined pressure and the
predetermined flow rate to restrict the predetermined pressure and
the predetermined flow rate to a curve of equal efficacy.
12. The system of claim 1 further comprising a variable resistance
in the air circuit, wherein the one or more controllers are
configured to control one or more of the pressure and the flow rate
of the air by adjusting the resistance of the variable
resistance.
13. The system of claim 1, wherein a controller of the one or more
controllers is configured to compute a target ventilation based on
anatomical deadspace information and a deadspace therapy reduction
value.
14. The system of claim 1, wherein a controller of the one or more
controllers is configured to generate a cardiac output estimate by
controlling a step change in the predetermined flow rate of the air
and determining a change in a measure of ventilation in relation to
the step change.
15. The system of claim 14, wherein the controller of the one or
more controllers is configured to initiate control of the step
change in the predetermined flow rate of the air in response to a
detection of sleep.
16. A method for controlling a supply of air to a patient's airways
for a respiratory therapy, the method comprising: identifying, by
one or more controllers, a predetermined pressure and a
predetermined flow rate of the air to be provided to a patient via
an air circuit and a patient interface; determining, with a
plurality of sensors, a pressure and a flow rate of the air being
provided to the patient via the patient interface; and controlling,
by the one or more controllers, a flow generator configured to
provide the air to the patient interface, and an adjustable vent so
as to simultaneously control the pressure and the flow rate of the
air at the patient interface to correspond with the predetermined
pressure and the predetermined flow rate, respectively.
17. The method of claim 16, wherein the patient interface comprises
a projection portion configured to conduct a flow of the air into a
naris of the patient and a mask portion configured to apply
pressure of the air to the patient.
18. The method of claim 17, wherein the flow generator provides the
flow of the air through the projection portion of the patient
interface thereby applying pressure of the air to the mask portion
of the patient interface.
19. The method of claim 16 further comprising maintaining, by the
one or more controllers, at least one of the predetermined pressure
and the predetermined flow rate at a constant value for a period of
time.
20. The method of claim 16 further comprising varying, by the one
or more controllers, the predetermined pressure in accordance with
a breathing cycle of the patient.
21. The method of claim 16, wherein the simultaneous control of the
pressure and the flow rate of the air comprises control of a
positive airway pressure therapy and a deadspace therapy.
22. The method of claim 21, wherein the positive airway pressure
therapy is a ventilation therapy.
23. The method of claim 16 further comprising determining, by the
one or more controllers, the predetermined pressure and the
predetermined flow rate so as to restrict the predetermined
pressure and the predetermined flow rate to a curve of equal
efficacy.
24. The method of claim 16, wherein controlling the adjustable vent
comprises adjusting, by the one or more controllers, a venting
characteristic of the adjustable vent in synchrony with the
patient's breathing cycle so as to maintain the pressure of the air
at the patient interface to correspond with the predetermined
pressure.
25. The method of claim 16 further comprising adjusting, by the one
or more controllers, a resistance of a variable resistance in the
air circuit so as to control one or more of the pressure and the
flow rate of the air.
26. The method of claim 16 further comprising calculating, in the
one or more controllers, a target ventilation based on anatomical
deadspace information and a deadspace therapy reduction value.
27. The method of claim 16 further comprising generating, in the
one or more controllers, a cardiac output estimate by controlling a
step change in the predetermined flow rate of the air and
determining a change in a measure of ventilation in relation to the
step change.
28. The method of claim 27 further comprising initiating, by the
one or more controllers, the controlling of the step change in the
predetermined flow rate of the air in response to a detection of
sleep.
Description
1 CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The present application is a continuation of U.S.
application Ser. No. 15/781,599, filed on Jun. 5, 2018, which is a
national phase entry under 35 U.S.C. .sctn. 371 of International
Application No. PCT/AU2016/051210, filed Dec. 9, 2016, published in
English, which claims priority from U.S. Provisional Application
No. 62/265,700, filed Dec. 10, 2015, all of which are incorporated
herein by reference.
2 STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR
DEVELOPMENT
[0002] Not Applicable
3 SEQUENCE LISTING
[0003] Not Applicable
4 BACKGROUND OF THE INVENTION
4.1 Field of the Invention
[0004] The present technology relates to one or more of the
detection, diagnosis, treatment, prevention and amelioration of
respiratory-related disorders. In particular, the present
technology relates to medical devices or apparatus, and their use
and may include devices for directing treatment gas to a patient's
respiratory system.
4.2 Description of the Related Art
[0005] 4.2.1 Human Respiratory System and its Disorders
[0006] The respiratory system of the body facilitates gas exchange.
The nose and mouth form the entrance to the airways of a
patient.
[0007] The airways include a series of branching tubes, which
become narrower, shorter and more numerous as they penetrate deeper
into the lung. The prime function of the lung is gas exchange,
allowing oxygen to move from the air into the venous blood and
carbon dioxide to move out. The trachea divides into right and left
main bronchi, which further divide eventually into terminal
bronchioles. The bronchi make up the conducting airways, and do not
take part in gas exchange. Further divisions of the airways lead to
the respiratory bronchioles, and eventually to the alveoli. The
alveolated region of the lung is where the gas exchange takes
place, and is referred to as the respiratory zone. See "Respiratory
Physiology", by John B. West, Lippincott Williams & Wilkins,
9th edition published 2011.
[0008] A range of respiratory disorders exist.
[0009] Obstructive Sleep Apnea (OSA), a form of Sleep Disordered
Breathing (SDB), is characterized by occlusion or obstruction of
the upper air passage during sleep. It results from a combination
of an abnormally small upper airway and the normal loss of muscle
tone in the region of the tongue, soft palate and posterior
oropharyngeal wall during sleep. The condition causes the affected
patient to stop breathing for periods typically of 30 to 120
seconds duration, sometimes 200 to 300 times per night. It often
causes excessive daytime somnolence, and it may cause
cardiovascular disease and brain damage. The syndrome is a common
disorder, particularly in middle aged overweight males, although a
person affected may have no awareness of the problem. See U.S. Pat.
No. 4,944,310 (Sullivan).
[0010] Cheyne-Stokes Respiration (CSR) is a disorder of a patient's
respiratory controller in which there are rhythmic alternating
periods of waxing and waning ventilation, causing repetitive
de-oxygenation and re-oxygenation of the arterial blood. It is
possible that CSR is harmful because of the repetitive hypoxia. In
some patients CSR is associated with repetitive arousal from sleep,
which causes severe sleep disruption, increased sympathetic
activity, and increased afterload. See U.S. Pat. No. 6,532,959
(Berthon-Jones).
[0011] Obesity Hyperventilation Syndrome (OHS) is defined as the
combination of severe obesity and awake chronic hypercapnia, in the
absence of other known causes for hypoventilation. Symptoms include
dyspnea, morning headache and excessive daytime sleepiness.
[0012] Chronic Obstructive Pulmonary Disease (COPD) encompasses any
of a group of lower airway diseases that have certain
characteristics in common. These include increased resistance to
air movement, extended expiratory phase of respiration, and loss of
the normal elasticity of the lung. Examples of COPD are emphysema
and chronic bronchitis. COPD is caused by chronic tobacco smoking
(primary risk factor), occupational exposures, air pollution and
genetic factors. Symptoms include: dyspnea on exertion, chronic
cough and sputum production.
[0013] Neuromuscular Disease (NMD) is a broad term that encompasses
many diseases and ailments that impair the functioning of the
muscles either directly via intrinsic muscle pathology, or
indirectly via nerve pathology. Some NMD patients are characterised
by progressive muscular impairment leading to loss of ambulation,
being wheelchair-bound, swallowing difficulties, respiratory muscle
weakness and, eventually, death from respiratory failure.
Neuromuscular disorders can be divided into rapidly progressive and
slowly progressive: (i) Rapidly progressive disorders:
Characterised by muscle impairment that worsens over months and
results in death within a few years (e.g. Amyotrophic lateral
sclerosis (ALS) and Duchenne muscular dystrophy (DMD) in
teenagers); (ii) Variable or slowly progressive disorders:
Characterised by muscle impairment that worsens over years and only
mildly reduces life expectancy (e.g. Limb girdle,
Facioscapulohumeral and Myotonic muscular dystrophy). Symptoms of
respiratory failure in NMD include: increasing generalised
weakness, dysphagia, dyspnea on exertion and at rest, fatigue,
sleepiness, morning headache, and difficulties with concentration
and mood changes.
[0014] Chest wall disorders are a group of thoracic deformities
that result in inefficient coupling between the respiratory muscles
and the thoracic cage. The disorders are usually characterised by a
restrictive defect and share the potential of long term hypercapnic
respiratory failure. Scoliosis and/or kyphoscoliosis may cause
severe respiratory failure. Symptoms of respiratory failure
include: dyspnea on exertion, peripheral oedema, orthopnea,
repeated chest infections, morning headaches, fatigue, poor sleep
quality and loss of appetite.
[0015] Otherwise healthy individuals may take advantage of systems
and devices to prevent respiratory disorders from arising.
[0016] 4.2.2 Therapies
[0017] Nasal Continuous Positive Airway Pressure (CPAP) therapy has
been used to treat Obstructive Sleep Apnea (OSA). The mechanism of
action is that continuous positive airway pressure acts as a
pneumatic splint and may prevent upper airway occlusion by pushing
the soft palate and tongue forward and away from the posterior
oropharyngeal wall.
[0018] Non-invasive ventilation (MV) provides ventilatory support
(pressure support) to a patient through the upper airways to assist
the patient in taking a full breath and/or maintain adequate oxygen
levels in the body by doing some or all of the work of breathing
(e.g., mechanical work of breathing). The ventilatory support is
provided via a patient interface. NIV has been used to treat CSR,
OHS, COPD, MD and Chest Wall disorders.
[0019] Invasive ventilation (IV) provides ventilatory support to
patients that are no longer able to effectively breathe themselves
and may be provided using a tracheostomy tube.
[0020] High Flow therapy (HFT) is the provision of a continuous,
heated, humidified flow of air to an entrance to the airway through
an unsealed or open interface at flow rates similar to, or greater
than peak inspiratory flow. HFT has been used to treat OSA, CSR,
COPD and other respiratory disorders. One mechanism of action is
that the high flow rate of air at the airway entrance improves
ventilation efficiency by flushing, or washing out, expired
CO.sub.2 from the patient's anatomical deadspace. HFT is thus
sometimes referred to as a deadspace therapy (DST).
[0021] Another form of flow therapy is supplemental oxygen therapy,
whereby air with an elevated percentage of oxygen is supplied to an
entrance to the airway through an unsealed interface.
[0022] 4.2.3 Systems
[0023] One known device used for treating sleep disordered
breathing is the S9 Sleep Therapy System, manufactured by ResMed.
Ventilators such as the ResMed Stellar.TM. Series of Adult and
Paediatric Ventilators may provide support for invasive and
non-invasive non-dependent ventilation for a range of patients for
treating a number of conditions such as but not limited to NMD, OHS
and COPD.
[0024] The ResMed Elisee.TM. 150 ventilator and ResMed VS III.TM.
ventilator may provide support for invasive and non-invasive
dependent ventilation suitable for adult or paediatric patients for
treating a number of conditions. These ventilators provide
volumetric and barometric ventilation modes with a single or double
limb circuit.
[0025] A treatment system may comprise a Positive Airway Pressure
(PAP) device/ventilator, an air circuit, a humidifier, a patient
interface, and data management.
[0026] 4.2.4 Patient Interface
[0027] A patient interface may be used to interface respiratory
equipment to its user, for example by providing a flow of air. The
flow of air may be provided via a mask to the nose and/or mouth, a
tube to the mouth or a tracheostomy tube to the trachea of the
user. Depending upon the therapy to be applied, the patient
interface may form a seal, e.g. with a face region of the patient,
to facilitate the delivery of gas at a pressure at sufficient
variance with ambient pressure to effect therapy, e.g. a positive
pressure of about 10 cm H.sub.2O. For other forms of therapy, such
as HFT, the patient interface may not include a seal sufficient to
facilitate delivery to the airways of a supply of gas at a positive
pressure of about 10 cm H.sub.2O.
[0028] 4.2.5 Respiratory Apparatus (PAP Device/Ventilator)
[0029] Examples of respiratory apparatuses include ResMed's S9
AutoSet.TM. PAP device and ResMed's Stellar.TM. 150 ventilator.
Respiratory apparatuses typically comprise a pressure generator,
such as a motor-driven blower or a compressed gas reservoir, and
are configured to supply a flow of air to the airway of a patient,
typically via a patient interface such as those described above. In
some cases, the flow of air may be supplied to the airway of the
patient at positive pressure. The outlet of the respiratory
apparatus is connected via an air circuit to a patient interface
such as those described above.
[0030] 4.2.6 Humidifier
[0031] Delivery of a flow of air without humidification may cause
drying of airways. Medical humidifiers are used to increase
humidity and/or temperature of the flow of air in relation to
ambient air when required, typically where the patient may be
asleep or resting (e.g. at a hospital). As a result, a medical
humidifier is preferably small for bedside placement, and it is
preferably configured to only humidify and/or heat the flow of air
delivered to the patient without humidifying and/or heating the
patient's surroundings.
5 BRIEF SUMMARY OF THE TECHNOLOGY
[0032] The present technology is directed towards providing medical
devices used in the diagnosis, amelioration, treatment, or
prevention of respiratory disorders having one or more of improved
comfort, cost, efficacy, ease of use and manufacturability.
[0033] A first aspect of the present technology relates to
apparatus used in the diagnosis, amelioration, treatment or
prevention of a respiratory disorder.
[0034] Another aspect of the present technology relates to methods
used in the diagnosis, amelioration, treatment or prevention of a
respiratory disorder.
[0035] Another aspect of the present technology relates to the
provision of a dead space therapy comprising a controlled
generation a flow of air towards a patient's respiratory cavity for
flushing expired gas (CO.sub.2) from the patient's anatomical
deadspace.
[0036] Another aspect of the present technology relates to the
provision of a pressure therapy comprising a controlled generation
of pressurized air at a patient's respiratory system, (e.g.,
pressure support therapy to mechanically assist with patient
respiration).
[0037] Another aspect of the present technology relates to methods
of providing such a pressure therapy and such a dead space therapy
simultaneously.
[0038] Another aspect of the present technology relates to
apparatus configured for provision of such a pressure therapy and
such a dead space therapy simultaneously or alternatively.
[0039] Some versions of the present technology may include a method
for controlling a supply of air to a patient's airways for a
respiratory therapy. The method may include identifying, by one or
more controllers, a predetermined pressure and a predetermined flow
rate of the air to be provided to a patient via a patient
interface. The method may include determining, with a plurality of
sensors, a pressure and a flow rate of the air being provided to
the patient via the patient interface. The method may include
controlling, by the one or more controllers, a first flow generator
and a second flow generator, each flow generator being configured
to provide a flow of the air to the patient interface, so as to
simultaneously control the pressure and the flow rate of the air at
the patient interface to correspond with the predetermined pressure
and the predetermined flow rate, respectively.
[0040] In some method versions, the controlling the first flow
generator and the second flow generator may include adjusting
output of at least one of the first flow generator and the second
flow generator. The patient interface may include a projection
portion configured to conduct a flow of the air into a naris of the
patient and a mask portion configured to apply pressure of the air
to the patient. The mask portion may be a nasal mask. The mask
portion may include nasal pillows. The method may include detecting
a continuous mouth leak, and reducing the predetermined pressure
upon detecting the continuous mouth leak. The first flow generator
may provide the flow of the air through the projection portion of
the patient interface and the second flow generator may apply
pressure of the air to the mask portion of the patient interface.
At least one, or both, of the predetermined pressure and the
predetermined flow rate may vary over a period of time
corresponding to a breathing cycle of the patient. The
predetermined flow rate may be constant for at least some
predetermined period of time and/or the predetermined pressure may
be constant during the predetermined period of time. The mask
portion of the patient interface further may include a vent.
[0041] In some versions, the method may include limiting the
predetermined flow rate to be less than a maximum flow rate. The
maximum flow rate may be a vent flow rate minus a peak expiratory
flow rate of the patient. The simultaneously controlling of the
pressure and the flow rate may further include controlling an
adjustment of the vent. The vent may include an active proximal
valve. The simultaneously controlling of the pressure and the flow
rate may be performed so as to provide the patient with a positive
airway pressure therapy and a deadspace therapy. The positive
airway pressure therapy may be a ventilation therapy. The method
may include determining, by the one or more controllers, the
predetermined pressure and the predetermined flow rate so as
restrict the predetermined pressure and the predetermined flow rate
to a curve of equal efficacy. The method may include calculating,
in a controller of the one or more controllers, a target
ventilation based on anatomical deadspace information and a
deadspace therapy reduction value. The method may include
generating, in a controller of the one or more controllers, a
cardiac output estimate by controlling a step change in the
predetermined flow rate of the air and determining a change in a
measure of ventilation in relation to the step change. The method
may include initiating, by the controller of the one or more
controllers, the controlling of the step change in the
predetermined flow rate of the air in response to a detection of
sleep.
[0042] Some versions of the present technology may include a system
for delivery of a flow of air to a patient's airways. The system
may include a first flow generator and a second flow generator,
each configured to provide air to a patient via a patient
interface. The system may include one or more controllers. The one
or more controllers may be configured to determine a pressure and a
flow rate of the air being provided to the patient via the patient
interface with a plurality of sensors. The one or more controllers
may be configured to control the first flow generator and the
second flow generator so as to simultaneously control the pressure
and the flow rate of the air at the patient interface to correspond
with a predetermined pressure and a predetermined flow rate,
respectively.
[0043] In some versions, the system may include the patient
interface, wherein the patient interface may include a projection
portion configured to conduct a flow of the air into a naris of the
patient and a mask portion configured to apply pressure of the air
to the patient. The mask portion may be a nasal mask. The mask
portion may be nasal pillows. The first flow generator may conduct
the flow of the air through the projection portion and the second
flow generator may apply pressure of the air to the mask portion.
The plurality of sensors may include a flow rate sensor and a
pressure sensor. An output of the first flow generator may be
measured by the flow rate sensor and an output of the second flow
generator may be measured by the pressure sensor. The one or more
controllers may be configured to maintain at least one of the
predetermined pressure and the predetermined flow rate at a
constant value for at least some period of time. The one or more
controllers may be further configured to vary at least one of the
predetermined pressure and the predetermined flow rate over a
period of time corresponding to a breathing cycle of the patient.
The mask portion of the patient interface may include a vent. The
one or more controllers may be configured to limit the
predetermined flow rate to be less than a maximum flow rate. The
one or more controllers may be configured to determine the maximum
flow rate by subtracting a peak expiratory flow rate of the patient
from a vent flow rate. The vent may be an adjustable vent and the
one or more controllers may be configured to control the adjustable
vent so as to control the pressure and the flow rate. The
adjustable vent may include an active proximal valve. The
simultaneous control of the pressure and the flow rate of the air
may provide the patient with a positive airway pressure therapy and
a deadspace therapy. The positive airway pressure therapy may be a
ventilation therapy.
[0044] In some versions, the one or more controllers may be
configured to determine the predetermined pressure and the
predetermined flow rate so as to restrict the predetermined
pressure and the predetermined flow rate to a curve of equal
efficacy. The one or more controllers may include one controller
configured to control the first flow generator and the second flow
generator. The one or more controllers may include a first
controller configured to control the first flow generator and a
second controller configured to control the second flow generator.
The first controller may be configured to obtain the flow rate of
the air being provided by the second flow generator. The second
controller may be configured to obtain the pressure of the air
being provided by the first flow generator. In some cases, a
controller of the one or more controllers may be configured to
compute a target ventilation based on anatomical deadspace
information and a deadspace therapy reduction value. A controller
of the one or more controllers may be configured to generate a
cardiac output estimate by controlling a step change in the
predetermined flow rate of the air and determining a change in a
measure of ventilation in relation to the step change. The
controller of the one or more controllers may be configured to
initiate control of the step change in the predetermined flow rate
of the air in response to a detection of sleep.
[0045] Some versions of the present technology may include a system
for delivery of a flow of air to a patient's airways. The system
may include a flow generator configured to provide air to a patient
via an air circuit and a patient interface. The system may include
an adjustable vent. The system may include one or more controllers.
The one or more controllers may be configured to determine a
pressure and a flow rate of the air being provided to the patient
via the patient interface with a plurality of sensors. The one or
more controllers may be configured to control the flow generator
and the adjustable vent so as to simultaneously control the
pressure and the flow rate of the air at the patient interface to
correspond with a predetermined pressure and a predetermined flow
rate, respectively.
[0046] In some versions, the system may include the patient
interface. The patient interface may include a projection portion
configured to conduct a flow of the air into a naris of a patient
and a mask portion configured to apply pressure of the air to the
patient. The adjustable vent may be part of the mask portion of the
patient interface. The plurality of sensors may include a pressure
sensor for determining a measured pressure of the air. The
plurality of sensors may include a flow rate sensor for determining
a measured flow rate of the air through the projection portion of
the patient interface. In some cases, at least one of the pressure
sensor and the flow rate sensor may be located at an output of the
flow generator. In some cases, at least one of the pressure sensor
and the flow rate sensor may be located at the patient interface.
The one or more controllers may be configured to maintain at least
one, or both, of the predetermined pressure and the predetermined
flow rate at a constant value for a period of time. The one or more
controllers may be further configured to vary the predetermined
pressure in accordance with a breathing cycle of the patient. The
simultaneous control of the pressure and the flow rate of the air
may provide the patient with a positive airway pressure therapy and
a deadspace therapy. The positive airway pressure therapy may be a
ventilation therapy. The one or more controllers may be configured
to determine the predetermined pressure and the predetermined flow
rate to restrict the predetermined pressure and the predetermined
flow rate to a curve of equal efficacy.
[0047] In some versions, the system may further include a variable
resistance in the air circuit, wherein the one or more controllers
may be configured to control one or more of the pressure and the
flow rate of the air by adjusting the resistance of the variable
resistance. In some cases, a controller of the one or more
controllers may be configured to compute a target ventilation based
on anatomical deadspace information and a deadspace therapy
reduction value. A controller of the one or more controllers may be
configured to generate a cardiac output estimate by controlling a
step change in the predetermined flow rate of the air and
determining a change in a measure of ventilation in relation to the
step change. The controller of the one or more controllers may be
configured to initiate control of the step change in the
predetermined flow rate of the air in response to a detection of
sleep.
[0048] Some versions of the present technology may include a method
for controlling a supply of air to a patient's airways for a
respiratory therapy. The method may include identifying, by one or
more controllers, a predetermined pressure and a predetermined flow
rate of the air to be provided to a patient via an air circuit and
a patient interface. The method may include determining, with a
plurality of sensors, a pressure and a flow rate of the air being
provided to the patient via the patient interface. The method may
include controlling, by the one or more controllers, a flow
generator configured to provide the air to the patient interface,
and an adjustable vent so as to simultaneously control the pressure
and the flow rate of the air at the patient interface to correspond
with the predetermined pressure and the predetermined flow rate,
respectively. The patient interface may include a projection
portion configured to conduct a flow of the air into a naris of the
patient and a mask portion configured to apply pressure of the air
to the patient. The flow generator may provide the flow of the air
through the projection portion of the patient interface thereby
applying pressure of the air to the mask portion of the patient
interface. The method may include maintaining, by the one or more
controllers, at least one of the predetermined pressure and the
predetermined flow rate at a constant value for a period of time.
The method may include varying, by the one or more controllers, the
predetermined pressure in accordance with a breathing cycle of the
patient. The simultaneous control of the pressure and the flow rate
of the air may include control of a positive airway pressure
therapy and a deadspace therapy. The positive airway pressure
therapy may be a ventilation therapy.
[0049] In some versions, the method may include determining, by the
one or more controllers, the predetermined pressure and the
predetermined flow rate so as to restrict the predetermined
pressure and the predetermined flow rate to a curve of equal
efficacy. The controlling of the adjustable vent comprises
adjusting, by the one or more controllers, a venting characteristic
of the adjustable vent in synchrony with the patient's breathing
cycle so as to maintain the pressure of the air at the patient
interface to correspond with the predetermined pressure. The method
may include adjusting, by the one or more controllers, a resistance
of a variable resistance in the air circuit so as to control one or
more of the pressure and the flow rate of the air. The method may
include calculating, in the one or more controllers, a target
ventilation based on anatomical deadspace information and a
deadspace therapy reduction value. The method may include
generating, in the one or more controllers, a cardiac output
estimate by controlling a step change in the predetermined flow
rate of the air and determining a change in a measure of
ventilation in relation to the step change. The method may include
initiating, by the one or more controllers, the controlling of the
step change in the predetermined flow rate of the air in response
to a detection of sleep.
[0050] In yet another aspect of the present technology, a supply of
air to a patient's airways may be controlled in connection with a
respiratory therapy. The respiratory therapy may include
identifying, by one or more controllers, a predetermined pressure
and a predetermined flow rate of air to be provided to a patient
via a patient interface; determining, by one or more sensors, a
pressure and a flow rate of the air being provided to a patient via
a patient interface; and controlling, by the one or more
controllers, a first flow generator and a second flow generator, so
as to simultaneously control the pressure and the flow rate of the
air to correspond with the predetermined pressure and the
predetermined flow rate, respectively. Controlling the first flow
generator and the second flow generator may include adjusting an
output of at least one of the first flow generator and the second
flow generator. In addition, the patient interface may include a
projection portion configured to conduct a flow of the air into a
naris of the patient and a mask portion configured to apply
pressure of the air to the patient. The first flow generator may
conduct the flow of the air through a projection portion of the
patient interface and the second flow generator may apply pressure
from the air to a mask portion of the patient interface.
[0051] In still another aspect, at least one of the predetermined
pressure and the predetermined flow rate may vary over a period of
time corresponding to a breathing cycle of the patient. The
predetermined flow rate may also be constant for at least some
predetermined period of time and the predetermined pressure may be
constant during the predetermined period of time.
[0052] In another aspect, the patient interface may include a vent,
and simultaneously controlling the pressure and the flow rate may
include controlling an adjustment of the vent. The vent may include
an adjustable proximal valve.
[0053] In still another aspect, simultaneously controlling the
pressure and the flow rate may be performed so as to provide the
patient with a pressure therapy and a deadspace therapy.
[0054] In another aspect, a system for delivery of a flow of air to
a patient's airways may include a first flow generator and a second
flow generator for providing air to a patient respiratory interface
and one or more controllers configured to: determine a pressure and
a flow rate of the air with a plurality of sensors, and control the
first flow generator and the second flow generator so as to
simultaneously control the pressure and the flow rate of the air at
the patient interface. The patient interface may include a
projection portion configured to conduct a flow of the air into a
naris of the patient and a mask portion configured to apply
pressure of the air to the patient. In addition, the first flow
generator may conduct the flow of the air through the projection
portion and the second flow generator may apply air pressure to the
mask portion. The plurality of sensors may include a flow sensor
and a pressure sensor, and an output of the first flow generator
may be measured by the flow sensor and an output of the first flow
generator may be measured by the pressure sensor. The controllers
may be configured to maintain at least one of the pressure and the
flow rate at a constant for at least some period of time. The
controllers may also be configured so that at least one of the
pressure and the flow rate is variable over a period of time. The
patient interface may include an adjustable vent and the one or
more controllers may be further configured to control the
adjustable vent.
[0055] In still another aspect, a system for delivery of a flow of
air to a patient's airways may include a flow generator for
providing air to a patient via a patient interface, an adjustable
vent, and one or more controllers. The one or more controllers may
be configured to determine a pressure and a flow rate of the air
with one or more sensors and control at least one of the flow
generator and the adjustable vent so as to simultaneously control
and vary the pressure and the flow rate of the air over a breathing
cycle of the patient. The patient interface may include a
projection portion configured to conduct a flow of the air into a
naris of a patient and a mask portion configured to apply pressure
of the air to the patient. The adjustable vent may be a part of the
mask portion of the patient interface. The system may also include
a pressure sensor for determining a measured pressure of the air
corresponding to the pressure of the air at the mask portion of the
patient interface and a flow sensor for determining a measured flow
rate of the air through the projection portion of the patient
interface. At least one of the pressure sensor and the flow sensor
may be located at an output of the flow generator or at the patient
interface. In addition, the controllers may be configured to vary
the pressure in accordance with a detected breathing cycle. The
flow generator may also include a first flow generator and a second
flow generator.
[0056] Of course, portions of the aspects may form sub-aspects of
the present technology. Also, various ones of the sub-aspects
and/or aspects may be combined in various manners and also
constitute additional aspects or sub-aspects of the present
technology.
[0057] Other features of the technology will be apparent from
consideration of the information contained in the following
detailed description, abstract, drawings and claims.
6 BRIEF DESCRIPTION OF THE DRAWINGS
[0058] The present technology is illustrated by way of example, and
not by way of limitation, in the figures of the accompanying
drawings, in which like reference numerals refer to similar
elements including:
6.1 Treatment Systems
[0059] FIG. 1A shows a system including a patient 1000 wearing a
patient interface 3000, in the form of a nasal pillows, receives a
supply of air at positive pressure from a Combination Therapy (CT)
device 4000. Air from the CT device is humidified in a humidifier
5000, and passes along an air circuit 4170 to the patient 1000. A
bed partner 1100 is also shown.
[0060] FIG. 1B shows a system including a patient 1000 wearing a
patient interface 3000, in the form of a nasal mask, receives a
supply of air at positive pressure from a CT device 4000. Air from
the CT device is humidified in a humidifier 5000, and passes along
an air circuit 4170 to the patient 1000.
[0061] FIG. 1C shows a system including a patient 1000 wearing a
patient interface 3000, in the form of a full-face mask, receives a
supply of air at positive pressure from a CT device 4000. Air from
the CT device is humidified in a humidifier 5000, and passes along
an air circuit 4170 to the patient 1000.
6.2 Therapy
[0062] 6.2.1 Respiratory System
[0063] FIG. 2 shows an overview of a human respiratory system
including the nasal and oral cavities, the larynx, vocal folds,
oesophagus, trachea, bronchus, lung, alveolar sacs, heart and
diaphragm.
[0064] FIG. 3 shows a patient interface in the form of a nasal mask
in accordance with one form of the present technology.
6.3 Combination Therapy (CT) Device
[0065] FIG. 4A shows example components of a CT device in
accordance with one form of the present technology.
[0066] FIG. 4B shows a schematic diagram of either a pressure
control or flow control pneumatic circuit of a CT device in
accordance with one form of the present technology. The directions
of upstream and downstream are indicated.
[0067] FIG. 4C shows a schematic diagram of the electrical
components of a CT device in accordance with one aspect of the
present technology.
6.4 Humidifier
[0068] FIG. 5 shows an isometric view of a humidifier suitable for
use with a respiratory apparatus.
6.5 Patient Interface
[0069] FIG. 6 shows a conventional nasal cannula;
[0070] FIG. 7 shows the nasal cannula of FIG. 6 in use with a
mask;
[0071] FIG. 8 is an illustration of a nasal cannula with a coupler
extension;
[0072] FIGS. 9A, 9B, 9C and 9D illustrate various cross sectional
profiles for coupler extensions of the present technology taken
along line A-A of FIG. 8;
[0073] FIG. 10A is an illustration of a nasal cannula with a
coupler extension in use with a mask;
[0074] FIG. 10B is an illustration of a nasal cannula with a
coupler extension in use with a mask showing a seat portion;
[0075] FIG. 11 is another illustration of a nasal cannula with a
coupler extension having a seat ridge, the figure also includes a
cross sectional view of the coupler extension taken along line
A-A;
[0076] FIG. 12 is another illustration of a nasal cannula with a
coupler extension FIG. 11 in use with a mask;
[0077] FIG. 13 is an illustration of another version of a nasal
cannula with a coupler extension in use with a mask;
[0078] FIG. 14A is a plan view and a front elevation view of
another example coupler extension for a nasal cannula of the
present technology;
[0079] FIG. 14B is a front elevation view of another coupler
extension for a nasal cannula;
[0080] FIG. 14C is a front elevation view of another coupler
extension for a nasal cannula;
[0081] FIG. 15A is an illustration nasal interface of the present
technology with nasal projections;
[0082] FIG. 15B is an illustration of another nasal interface with
nasal projections;
[0083] FIG. 16 shows the nasal interface of FIG. 15A in use by a
patient;
[0084] FIG. 17A and 17B show elevation and cross sectional views
respectively of a further example nasal interface;
[0085] FIG. 18 is an illustration of a further nasal interface with
a pillow vent;
[0086] FIG. 19A and 19B are illustrations of a further nasal
interface with pillow vents in showing inspiratory flow and
expiratory flow respectively;
[0087] FIG. 20A and 20B are illustrations of a further nasal
interface with vents showing expiratory and inspiratory operations
respectively;
[0088] FIG. 20C and 20D are illustrations of a further nasal
interface with vents showing expiratory and inspiratory operations
respectively;
[0089] FIG. 20E and 20F are illustrations of a further nasal
interface with vents showing expiratory and inspiratory operations
respectively;
[0090] FIG. 21 is an illustration of a nasal pillow with a further
example nasal projection;
[0091] FIG. 22 is an illustration of a valve membrane of the
example nasal projection of FIG. 21;
[0092] FIGS. 23A and 23B show expiratory and inspiratory operations
respectively of the valve membrane of the example nasal projection
of FIG. 21;
[0093] FIG. 24 illustrates an external side view of a mask frame
with interface ports for coupling with supply conduits;
[0094] FIG. 25A shows a plenum chamber or patient side of a mask
frame for some versions of the present technology;
[0095] FIG. 25B shows another plenum chamber or patient side of a
mask frame of another version of the present technology;
6.6 Combination Therapy System
[0096] FIG. 26 is an example schematic diagram of a combination
therapy system in accordance with some versions of the present
technology;
[0097] FIG. 27 shows an electrical circuit model representing the
flow of air in a combination therapy system in accordance with some
versions of the present technology;
[0098] FIG. 28 is another example schematic diagram of a
combination therapy system in accordance with some versions of the
present technology;
[0099] FIG. 29 is an example control methodology diagram for a
combination therapy in accordance with some versions of the present
technology;
[0100] FIG. 30 is a graph illustrating the relationship between
interface pressure and vent flow in one implementation of the
present technology;
[0101] FIG. 31 is a graph illustrating the relationship between
interface pressure and vent flow in one implementation of the
present technology;
[0102] FIG. 32 is a graph illustrating the additive or
complementary nature of combination therapy according to the
present technology; and
[0103] FIG. 33 shows an electrical circuit model representing the
flow of air in a combination therapy system in accordance with
another implementation of the present technology.
7 DETAILED DESCRIPTION OF EXAMPLES OF THE TECHNOLOGY
[0104] Before the present technology is described in further
detail, it is to be understood that the technology is not limited
to the particular examples described herein, which may vary. It is
also to be understood that the terminology used in this disclosure
is for the purpose of describing only the particular examples
discussed herein, and is not intended to be limiting.
7.1 Therapy
[0105] In one form, the present technology comprises a control
method for treating a respiratory disorder comprising controlling
positive pressure to the entrance of the airways of a patient 1000
so as to provide pressure therapy as well as controlling the flow
rate of air to the patient, so as to provide deadspace therapy, so
as to allow for anatomical and/or apparatus deadspace flushing.
7.2 Treatment Systems
[0106] In one form, the present technology comprises an apparatus
for treating a respiratory disorder. The apparatus may comprise a
CT device 4000 for supplying pressurised air to the patient 1000
via an air circuit 4170 to a patient interface 3000.
7.3 Patient Interface
[0107] A non-invasive patient interface 3000 in accordance with one
aspect of the present technology comprises the following functional
aspects: a seal-forming structure 3100, a plenum chamber 3200, a
positioning and stabilising structure 3300, a vent 3400, a
decoupling structure 3500, a connection port 3600 for connection to
air circuit 4170, and a forehead support 3700. In some forms a
functional aspect may be provided by one or more physical
components. In some forms, one physical component may provide one
or more functional aspects. In use the seal-forming structure 3100
is arranged to surround an entrance to the airways of the patient
so as to facilitate the supply of air at positive pressure to the
airways.
[0108] An alternative non-invasive patient interface is an
oro-nasal interface (full-face mask) that seals around both the
nose and the mouth of the patient 1000.
7.4 Combination Therapy (CT) Device
[0109] An example CT device 4000 in accordance with one aspect of
the present technology may comprise mechanical and pneumatic
components 4100, electrical components 4200 and may be programmed
to execute one or more therapy algorithms. The CT device preferably
has an external housing 4010, preferably formed in two parts, an
upper portion 4012 and a lower portion 4014. Furthermore, the
external housing 4010 may include one or more panel(s) 4015.
Preferably the CT device 4000 comprises a chassis 4016 that
supports one or more internal components of the CT device 4000. In
one form one, or a plurality of, pneumatic block(s) 4020 (e.g.,
two) is supported by, or formed as part of the chassis 4016. The CT
device 4000 may include a handle 4018.
[0110] The CT device 4000 may have one or more pneumatic paths
depending on the types of patient interface coupled with the
device. A pneumatic path of the CT device 4000 may comprise an
inlet air filter 4112, an inlet muffler 4122, a pressure device
4140 capable of supplying air at positive pressure (such as a
blower 4142) and a flow device 4141 capable of supplying air at a
desired or target flow rate (e.g., a blower or oxygen supply line
etc.), one or more pneumatic blocks 4020 and an outlet muffler
4124. One or more transducers 4270, such as pressure sensors or
pressure transducers 4274 and flow rate sensors or flow transducers
4272 may be included in the pneumatic path(s). Each pneumatic block
4020 may comprise a portion of the pneumatic path that is located
within the external housing 4010 and may house either pressure
device 4140 or flow device 4141.
[0111] The CT device 4000 may have an electrical power supply 4210,
one or more input devices 4220, a central controller 4230, a
therapy device controller 4240, a pressure device 4140, flow device
4141, one or more protection circuits 4250, memory 4260,
transducers 4270, data communication interface 4280 and one or more
output devices 4290. Electrical components 4200 may be mounted on a
single Printed Circuit Board Assembly (PCBA) 4202. In an
alternative form, the CT device 4000 may include more than one PCBA
4202.
[0112] The CT device 4000 may be configured to control provision of
any of the pressure and/or flow therapies described throughout this
specification.
[0113] 7.4.1 CT Device Mechanical & Pneumatic Components
4100
[0114] 7.4.1.1 Air Filter(s) 4110
[0115] A CT device in accordance with one form of the present
technology may include an air filter 4110, or a plurality of air
filters 4110 for each pneumatic path.
[0116] In one form, an inlet air filter 4112 is located at the
beginning of the pneumatic path upstream of a pressure device 4140.
See FIG. 4B.
[0117] In one form, an outlet air filter 4114, for example an
antibacterial filter, is located between an outlet of the pneumatic
block 4020 and a patient interface 3000. See FIG. 4B.
[0118] 7.4.1.2 Muffler(s) 4120
[0119] In one form of the present technology, an inlet muffler 4122
is located in the pneumatic path upstream of a pressure device
4140. See FIG. 4B.
[0120] In one form of the present technology, an outlet muffler
4124 is located in the pneumatic path between the pressure device
4140 and a patient interface 3000. See FIG. 4B.
[0121] 7.4.1.3 Pressure Device 4140 and Flow Device 4141
[0122] In one form of the present technology, CT device 4000 may
contain two flow generators, such as a pressure device 4140 and a
flow device 4141 (see FIG. 4C). Pressure device 4140 may provide a
supply of air at positive pressure to a first portion of the
patient interface 3000, and flow device 4141 may provide a flow of
air to a second portion of patient interface 3000. Each flow
generator may include a controllable blower 4142. For example the
blower 4142 may include a brushless DC motor 4144 with one or more
impellers housed in a volute. The blower may be preferably capable
of delivering a supply of air, for example at a rate of up to about
120 litres/minute, at a positive pressure in a range from about 4
cm H.sub.2O to about 20 cm H.sub.2O, or in other forms up to about
30 cm H.sub.2O. The blower may include a blower as described in any
one of the following patents or patent applications the contents of
which are incorporated herein in their entirety: U.S. Pat. Nos.
7,866,944; 8,638,014, 8,636,479; and PCT patent application
publication number WO 2013/020167.
[0123] The pressure device 4140 and flow device 4141 may operate
under the control of the therapy device controller 4240.
Alternatively, the pressure device 4140 and the flow device 4141
may operate under the control of separate controllers.
[0124] In other forms, a pressure device 4140 or flow device 4141
may be a piston-driven pump, a pressure regulator connected to a
high pressure source (e.g. compressed air reservoir) or
bellows.
[0125] 7.4.1.4 Transducer(s) 4270
[0126] Transducers may be internal of the device, or external of
the CT device. External transducers may be located for example on
or form part of the air circuit, e.g. the patient interface.
External transducers may be in the form of non-contact sensors such
as a Doppler radar movement sensor that transmit or transfer data
to the CT device.
[0127] In one form of the present technology, one or more
transducers 4270 are located upstream and/or downstream of the
pressure device 4140. The one or more transducers 4270 may be
constructed and arranged to measure properties such as a flow rate,
a pressure or a temperature at that point in the pneumatic
path.
[0128] In one form of the present technology, one or more
transducers 4270 may be located proximate to the patient interface
3000.
[0129] In one form, a signal from a transducer 4270 may be
filtered, such as by low-pass, high-pass or band-pass
filtering.
[0130] 7.4.1.4.1 Flow Transducer 4272
[0131] A flow transducer 4272 in accordance with the present
technology may be based on a differential pressure transducer, for
example, an SDP600 Series differential pressure transducer from
SENSIRION.
[0132] In use, a signal representing a flow rate from the flow
transducer 4272 is received by the central controller 4230.
[0133] 7.4.1.4.2 Pressure Transducer 4274
[0134] A pressure transducer 4274 in accordance with the present
technology is located in fluid communication with the pneumatic
circuit. An example of a suitable pressure transducer is a sensor
from the HONEYWELL ASDX series. An alternative suitable pressure
transducer is a sensor from the NPA Series from GENERAL
ELECTRIC.
[0135] In use, a signal from the pressure transducer 4274, is
received by the central controller 4230.
[0136] 7.4.1.4.3 Motor Speed Transducer 4276
[0137] In one form of the present technology a motor speed
transducer 4276 is used to determine a rotational velocity of the
motor 4144 and/or the blower 4142. A motor speed signal from the
motor speed transducer 4276 is preferably provided to the therapy
device controller 4240. The motor speed transducer 4276 may, for
example, be a speed sensor, such as a Hall effect sensor.
[0138] 7.4.1.5 Anti-Spill Back Valve 4160
[0139] In one form of the present technology, an anti-spill back
valve is located between the humidifier 5000 and the pneumatic
block 4020. The anti-spill back valve is constructed and arranged
to reduce the risk that water will flow upstream from the
humidifier 5000, for example to the motor 4144.
[0140] 7.4.1.6 Air Circuit 4170
[0141] An air circuit 4170 in accordance with an aspect of the
present technology is a conduit or a tube constructed and arranged
in use to allow a flow of air to travel between two components such
as the pneumatic block 4020 and the patient interface 3000.
[0142] In particular, the air circuit may be in fluid connection
with the outlet of the pneumatic block and the patient interface.
The air circuit may be referred to as air delivery tube. In some
cases there may be separate limbs of the circuit for inhalation and
exhalation and/or for multiple patient interfaces. In other cases a
single limb is used.
[0143] 7.4.1.7 Oxygen Delivery 4180
[0144] In one form of the present technology, supplemental oxygen
4180 is delivered to one or more points in the pneumatic path, such
as upstream of the pneumatic block 4020, to the air circuit 4170
and/or to the patient interface 3000, such as via the nasal
projections or prongs of a cannula.
[0145] 7.4.2 CT Device Electrical Components 4200
[0146] 7.4.2.1 Power Supply 4210
[0147] A power supply 4210 may be located internal or external of
the external housing 4010 of the CT device 4000.
[0148] In one form of the present technology power supply 4210
provides electrical power to the CT device 4000 only. In another
form of the present technology, power supply 4210 provides
electrical power to both CT device 4000 and humidifier 5000.
[0149] 7.4.2.2 Input Devices 4220
[0150] In one form of the present technology, a CT device 4000
includes one or more input devices 4220 in the form of buttons,
switches or dials to allow a person to interact with the device.
The buttons, switches or dials may be physical devices, or software
devices accessible via a touch screen. The buttons, switches or
dials may, in one form, be physically connected to the external
housing 4010, or may, in another form, be in wireless communication
with a receiver that is in electrical connection to the central
controller 4230.
[0151] In one form the input device 4220 may be constructed and
arranged to allow a person to select a value and/or a menu
option.
[0152] 7.4.2.3 Central Controller 4230
[0153] In one form of the present technology, the central
controller 4230 is one or a plurality of processors suitable to
control a CT device 4000.
[0154] Suitable processors may include an x86 INTEL processor, a
processor based on ARM Cortex-M processor from ARM Holdings such as
an STM32 series microcontroller from ST MICROELECTRONIC. In certain
alternative forms of the present technology, a 32-bit RISC CPU,
such as an STR9 series microcontroller from ST MICROELECTRONICS or
a 16-bit RISC CPU such as a processor from the MSP430 family of
microcontrollers, manufactured by TEXAS INSTRUMENTS may also be
suitable.
[0155] In one form of the present technology, the central
controller 4230 is a dedicated electronic circuit.
[0156] In one form, the central controller 4230 is an
application-specific integrated circuit. In another form, the
central controller 4230 comprises discrete electronic
components.
[0157] The central controller 4230 may be configured to receive
input signal(s) from one or more transducers 4270, and one or more
input devices 4220.
[0158] The central controller 4230 may be configured to provide
output signal(s) to one or more of an output device 4290, a therapy
device controller 4240, a data communication interface 4280 and
humidifier controller 5250.
[0159] In some forms of the present technology, the central
controller 4230is configured to implement the one or more
methodologies described herein such as the one or more algorithms.
In some cases, the central controller 4230 may be integrated with a
CT device 4000. However, in some forms of the present technology
the central controller 4230 may be implemented discretely from the
flow generation components of the CT device 4000, such as for
purpose of performing any of the methodologies described herein
without directly controlling delivery of a respiratory treatment.
For example, the central controller 4230 may perform any of the
methodologies described herein for purposes of determining control
settings for a ventilator or other respiratory related events by
analysis of stored data such as from any of the sensors described
herein.
[0160] 7.4.2.4 Clock 4232
[0161] Preferably CT device 4000 includes a clock 4232 that is
connected to the central controller 4230.
[0162] 7.4.2.5 Therapy Device Controller 4240
[0163] In one form of the present technology, therapy device
controller 4240 is a pressure control module 4330 that forms part
of the algorithms executed by the central controller 4230. The
therapy device controller 4240 may be a flow control module that
forms part of the algorithms executed by the central controller
4230. In some examples it may be both a pressure control and flow
control module.
[0164] In one form of the present technology, therapy device
controller 4240 may be one or more dedicated motor control
integrated circuits. For example, in one form a MC33035 brushless
DC motor controller, manufactured by ONSEMI is used.
[0165] 7.4.2.6 Protection Circuits 4250
[0166] Preferably a CT device 4000 in accordance with the present
technology comprises one or more protection circuits 4250.
[0167] The one or more protection circuits 4250 in accordance with
the present technology may comprise an electrical protection
circuit, a temperature and/or pressure safety circuit.
[0168] 7.4.2.7 Memory 4260
[0169] In accordance with one form of the present technology the CT
device 4000 includes memory 4260, preferably non-volatile memory.
In some forms, memory 4260 may include battery powered static RAM.
In some forms, memory 4260 may include volatile RAM.
[0170] Preferably memory 4260 is located on the PCBA 4202. Memory
4260 may be in the form of EEPROM, or NAND flash.
[0171] Additionally or alternatively, CT device 4000 includes
removable form of memory 4260, for example a memory card made in
accordance with the Secure Digital (SD) standard.
[0172] In one form of the present technology, the memory 4260 acts
as a non-transitory computer readable storage medium on which is
stored computer program instructions expressing the one or more
methodologies described herein, such as the one or more
algorithms.
[0173] 7.4.2.8 Data Communication Systems 4280
[0174] In one preferred form of the present technology, a data
communication interface 4280 is provided, and is connected to the
central controller 4230. Data communication interface 4280 is
preferably connectable to remote external communication network
4282 and/or a local external communication network 4284. Preferably
remote external communication network 4282 is connectable to remote
external device 4286. Preferably local external communication
network 4284 is connectable to local external device 4288.
[0175] In one form, data communication interface 4280 is part of
the central controller 4230. In another form, data communication
interface 4280 is separate from the central controller 4230, and
may comprise an integrated circuit or a processor.
[0176] In one form, remote external communication network 4282 is
the Internet. The data communication interface 4280 may use wired
communication (e.g. via Ethernet, or optical fibre) or a wireless
protocol (e.g. CDMA, GSM, LTE) to connect to the Internet.
[0177] In one form, local external communication network 4284
utilises one or more communication standards, such as Bluetooth, or
a consumer infrared protocol.
[0178] In one form, remote external device 4286 is one or more
computers, for example a cluster of networked computers. In one
form, remote external device 4286 may be virtual computers, rather
than physical computers. In either case, such remote external
device 4286 may be accessible to an appropriately authorised person
such as a clinician.
[0179] Preferably local external device 4288 is a personal
computer, mobile phone, tablet or remote control.
[0180] 7.4.2.9 Output Devices Including Optional Display,
Alarms
[0181] An output device 4290 in accordance with the present
technology may take the form of one or more of a visual, audio and
haptic unit. A visual display may be a Liquid Crystal Display (LCD)
or Light Emitting Diode (LED) display.
[0182] 7.4.2.9.1 Display Priver 4292
[0183] A display driver 4292 receives as an input the characters,
symbols, or images intended for display on the display 4294, and
converts them to commands that cause the display 4294 to display
those characters, symbols, or images.
[0184] 7.4.2.9.2 Display 4294
[0185] A display 4294 is configured to visually display characters,
symbols, or images in response to commands received from the
display driver 4292. For example, the display 4294 may be an
eight-segment display, in which case the display driver 4292
converts each character or symbol, such as the figure "0", to eight
logical signals indicating whether the eight respective segments
are to be activated to display a particular character or
symbol.
7.5 Humidifier
[0186] In one form of the present technology there is provided a
humidifier 5000 as shown in FIG. 5 to change the absolute humidity
of air for delivery to a patient relative to ambient air.
Typically, the humidifier 5000 is used to increase the absolute
humidity and increase the temperature of the flow of air relative
to ambient air before delivery to the patient's airways.
7.6 Combination Therapy Applications
[0187] As previously described, the patient interface 3000 and CT
device 4000 permit an application of various positive airway
pressure (PAP) therapies, such as CPAP or bi-level PAP therapy or
ventilation, or any other pressure therapy mentioned in this
specification. In addition, the disclosed system may provide flow
therapies, including deadspace therapies, such as high flow therapy
("HFT"). In HFT, air may be delivered to the nasal passages at a
high flow rate, such as in the range of about 10 to about 35
litres/minute. A combination of these therapies may be provided to
the patient using the disclosed technology, such as through
providing a patient with a combination of pressure therapy (e.g.,
CPAP) and deadspace therapy (e.g., HFT). The combined flow and
pressure therapies may be supplied by a common apparatus, such as
CT device 4000, or by separate apparatuses. In addition, changes in
a patient's therapy may be applied with no or minimal changes to
the configuration of patient interface on the patient.
[0188] For example, the CT device 4000 previously described may be
coupled via a delivery conduit (air circuit 4170) to the full-face
mask 8008 (see e.g., FIG. 7) or via a delivery conduit (air circuit
4170) to the base portion 16016 of the patient interface 16002 (see
FIG. 15A), so as to control pressure delivered to the mask or the
chamber of each naris pillow. In this way, a pressure therapy can
be controlled by a pressure control loop of a controller 4230 of
the CT device 4000 so as to control a measure of interface pressure
to meet a predetermined target pressure. The measure of interface
pressure may be determined for example by a pressure sensor. Such
target pressures may be modified over time, such as in synchrony
with detected patient's respiration (e.g., Bi-level therapy or
Pressure Support) or expected patient respiration (timed backup
breath). The seal of the mask or the naris pillows will permit the
pressure to be controlled at the entrance to the patient's
respiratory system.
[0189] In addition to the delivery of a controlled pressure to
patient interface 3000, a controlled flow of air may also be
provided to the patient via patient interface 3000. For example,
supplemental oxygen may be supplied by the one or more prongs
7004a, 7004b of the nasal cannula of FIGS. 6 and 7, or one or more
of the nasal projections 16100 of FIG. 15 or 17. By way of further
example, HFT may be supplied to the one or more prongs 9004a, 9004b
of the nasal cannula of, for example, FIG. 6, 7 or 8, or the nasal
projections 16100 of the patient interface of FIG. 15 or 17 such as
by a flow generator configured to provide HFT. In such a case, an
additional flow generator or oxygen flow source may be coupled by a
projection conduit 17170 to the nasal projection or may be coupled
by one or more lumens 9012 to the prongs 9004. Optionally, the flow
of gas to the prongs or nasal projections may be controlled by a
flow control loop of a controller. For example, the flow can be
controlled by a flow control loop of a controller of the flow
generator or supplemental gas source so as to control a measure of
flow rate of air to meet a predetermined target flow rate. The
measure of flow rate may be determined for example by a flow rate
sensor. The prongs of the cannula and/or nasal projections can
permit a supply of air, such as at high flow rates, within the
patient's nasal passages.
[0190] In an alternative implementation, the controlled flow of air
may be delivered to the mouth via an oral interface such as that
described in PCT Publication no. WO 2013/163685, the entire
contents of which are herein incorporated by reference. The oral
interface may be positioned within a full-face mask such as the
mask 8008, or beneath a nasal mask such as the mask 3000.
[0191] FIG. 26 illustrates a block diagram of an example CT device
4000 by which a controlled pressure and flow rate of air may be
provided to a patient via patient interface 3000. As described
above in connection with FIG. 4C, pressure device 4140 may be
controlled by therapy device controller 4240. The pressurized air
from pressure device 4140 may be transmitted to patient interface
3000 via one or more pneumatic paths, such as air circuit 4170,
which connects with patient interface 3000 at connection port 3600.
A pressure sensor 4274 may be configured to measure the pressure of
the air associated with the air circuit 4170. A flow rate sensor
(not shown) may be configured to measure the flow rate of the air
through air circuit 4170. In addition to pressure device 4140, flow
device 4141 may provide a flow of air to patient interface 3000 via
one or more pneumatic paths, such as projection conduit 17170.
Projection conduit 17170 may connect to patient interface 3000 at
one or more secondary ports 19100. A flow rate sensor 4272 may be
configured to measure the flow rate of the air through projection
conduit 17170. As set forth above, flow device 4141 may also be
controlled by therapy device controller 4240. Patient interface
3000 may also include a vent 3400 to allow air to flow out of
patient interface 3000 to atmosphere.
[0192] The flow rate of air that is provided to the patient at
patient interface 3000 will depend on the characteristics of vent
3400, which may be adjustable, as well as the pressure at patient
interface 3000. For example, the flow rate of air out of vent 3400
may correspond with the pressure at patient interface 3000. This
correspondence may be quadratic in nature, in which the square of
the flow rate out of vent 3400 may approximately correspond to the
air pressure in patient interface 3000. Accordingly, the flow rate
measured at flow rate sensor 4272 will correspond to both the flow
of air into the patient's airways as well as the flow of air
through vent 3400. In addition, the flow rate may also vary based
on the configuration of other components, such as the configuration
of projection conduit 17170. Accordingly, in order to provide the
patient with a desired flow rate, therapy device controller 4240
may calculate what the flow rate to the patient will be based on
the parameters of the system's various components. For example,
therapy device controller 4240 may access data from pressure sensor
4274 so as to calculate the flow rate out of vent 3400. Therapy
device controller 4240 may then compensate the flow rate measured
at flow rate sensor 4272 by the calculated flow rate out of vent
3400, so as to determine the effective flow rate of air being
provided to the patient. In addition, by controlling both the
pressure and the flow rate of air into patient interface 3000, CT
device 4000 may control the deadspace flushing flow rate out of
vent 3400.
[0193] In controlling the output of pressure device 4140 and flow
device 4141, therapy device controller 4240 may simultaneously
control the pressure and the flow rate of the air being provided to
the patient via patient interface 3000. In this way, the disclosed
system may provide the patient with a combination of respiratory
therapies. For example, therapy device controller 4240 may control
pressure device 4140 and flow device 4141 so that a patient is
provided with CPAP therapy by having a constant pressure at patient
interface 3000, while also providing HFT at a constant flow rate
via projection conduit 17170. Therapy device controller 4240 may be
configured so that the pressure and flow rate of air are considered
to be constant if the measured pressure and the measured flow rate
each remain within some predetermined threshold range.
[0194] In addition, therapy device controller 4240 may vary the
pressure and/or the flow rate of the air in accordance with a
predetermined therapy. For example, the pressure device 4140 and
flow device 4141 may be controlled so as to provide a bi-level
pressure therapy or a CPAP therapy with expiratory pressure relief
in which the pressure of the air at patient interface 3000
increases during a first period of time corresponding to the
patient's inspiration and decreases during a second period of time
corresponding to the patient's expiration. During these periods of
time the flow rate of the air may also be controlled so that the
flow rate varies by some predetermined amount in correspondence
with the patient's inspiration and expiration. In another example,
the flow rate of the air may be held constant while the pressure at
patient interface 3000 is varied.
[0195] Alternatively, the pressure may be held constant (e.g.,
CPAP), while the flow rate is varied. Pressure device 4140 and flow
device 4141 may also be simultaneously controlled so that the
pressure and flow rate of the air are both continuously varying
over some period of time in accordance with a therapy that calls
for some predetermined, but varying, pressure and flow rate.
[0196] In another example, pressure device 4140 and flow device
4141 may also be simultaneously controlled so as to provide for
auto-titrating CPAP therapy (e.g., APAP) along with HFT. For
example, a treatment pressure may be increased upon detection of
one or more Sleep Disordered Breathing events. The flow rate of the
HFT may be maintained relatively constant or similarly adjusted
based on such detections. Accordingly, a deadspace therapy that
would be otherwise compromised by OSA can be made more effective
through a pressure therapy, such as APAP, that opens the patient's
upper airways.
[0197] In yet another example, pressure device 4140 and flow device
4141 may be controlled in a manner that allows for the patient to
reach some target amount of ventilation, such as by controlling
pressure to provide pressure support therapy. For example, the
pressure device 4140 of the disclosed CT system may implement
adaptive servo-ventilation (ASV) therapy in combination with the
high flow therapies described herein. Thus, the pressure may
oscillate synchronously with patient's breathing cycle or with
timed machine generated breaths to enforce a target ventilation.
Similarly, the flow rate may be controlled to remain constant or it
may be controlled to vary such as as a function of the patient's
detected breathing cycle or as a function of the target
ventilation.
[0198] By combining pressure and flow therapies, the disclosed
system may provide the patient with a more effective overall
therapy. For example, the effectiveness of an HFT therapy is
diminished if the upper airway of the patient is closed. The
patient's airway may be opened through the use of various pressure
therapies, such as a PAP treatment pressure (e.g., APAP or CPAP).
Therefore, HFT therapy may be made to be more effective by being
combined with a pressure therapy.
[0199] Pressure support or ventilation therapy reduces the work
required from the patient for breathing by providing mechanical
pressure support and may allow for greater recovery of alveolar
deadspace, as airways to the lungs are opened by the pressure
support. Flow therapy, such as HFT, also reduces the work of
breathing and allows for greater recovery of anatomical deadspace
by flushing carbon dioxide rich areas of the patient's airways with
air. A combination of pressure therapy and flow therapy may also
assist a patient in achieving sufficient positive end-expiratory
pressure (PEEP). In this way, a combination of a flow therapy and a
pressure therapy may allow a patient who experiences insufficient
minute ventilation or alveolar ventilation to receive a greater
volume of gas exchange within the patient's lungs through the
removal of anatomical and alveolar deadspace and the increase in
tidal volume that is being provided to the patient's lungs. In
addition, simultaneous HFT may also allow pressure support therapy
to be administered at a lower level of pressure support, thereby
improving the acceptability of the pressure support therapy. For
example, excessive levels of pressure support can induce lung
injury. As another example, using pressure support to force air
through bronchitis lung produces high flow velocity in the
bronchial flow paths, which can cause discomfort and even further
inflammation. As another example, pressure support therapy results
in a cyclic acoustic noise pattern whose volume increases with the
level of pressure support.
[0200] Accordingly, a combination of one or more pressure therapies
with one or more flow therapies, as described herein, may be
additive or complementary. For example, FIG. 32 contains a graph
32000 illustrating the possible effects of combination therapy on a
hypercapnic patient (one with elevated PCO.sub.2). The horizontal
axis represents the flushing flow rate of the combination therapy
and the vertical axis represents a pressure support of a
combination therapy in which the pressure therapy is a bi-level
therapy. The point 32010 represents a therapy in which the pressure
support is zero but the flushing flow rate is high, e.g. 100 litres
per minute. In such a case, the therapy can be considered as
essentially just a deadspace therapy. The point 32020 represents a
therapy in which the pressure support is high, e.g. 20 cm H.sub.2O,
but the flushing flow rate is zero. In such a case, the therapy can
be considered as essentially just a pressure support therapy. The
points 32010 and 32020 represent forms of therapy which are equally
effective by some measure, e.g. reducing the PCO.sub.2 by 15%. Both
however are "extreme" forms, i.e. involve high flushing flow rate
and zero pressure support, or high pressure support and zero
flushing flow rate respectively. All points along the curve 32030
may represent combination therapies that are as effective as the
extreme therapies represented by the points 32010 and 32020, but
are more moderate in both pressure support and flushing flow rate
than either of those extreme therapies. The present technology
allows any point on the curve 32030, e.g. the point 32040,
representing a combination therapy with moderate pressure support
and flushing flow rate, to be chosen for a patient depending on the
preferences and characteristics of the patient, without altering
the effectiveness of the combination therapy. The curve 32030 may
be referred to as a curve of equal efficacy. In essence, the
combination therapy may have a synergistic effect depending on
settings that can provide treatment as effective as either one of
the individual therapies but at reduced levels so as to
unexpectedly reduce the potential for negative consequences that
may be associated with higher levels of each individual
therapy.
[0201] Accordingly, in some versions, controller(s) of apparatus
for generating such combination therapy may be configured with such
a curve (e.g., data values or a programmed function in a memory
representing such a curve) to regulate a synergistic control of the
therapies. For example, if a condition is detected by the
controller, a change in the combination therapy may be made by
automatically varying the setting of each control parameter (e.g.,
target pressure and target flow rate) so that they are restricted
to the curve. By way of further example, if a change is made to the
setting of a control parameter for one therapy (either
automatically or manually), the control parameter for the other
therapy may be set or recommended by the controller according to
such a curve to complement the change to the first control
parameter. Thus, the controller(s) may be configured to vary a
target pressure and/or a target flow rate so as to restrict them to
a predetermined curve of equal efficacy.
[0202] In accordance with the presently disclosed technology, the
combination of a pressure therapy and a flow therapy may take a
number of different forms. For example, a constant pressure (e.g.,
CPAP) may be used in combination with either a variable or a
constant flow rate. In another example, the pressure therapy may
provide a semi-fixed pressure that is adjusted in accordance with a
patient's detected breathing events (e.g., obstructive apnea,
hypopnea, etc.). In particular, the pressure therapy (e.g. APAP)
may be provided in accordance with an AutoSee.TM. pressure that is
automatically set by the pressure controller to a minimum pressure
needed to keep the patient's airways open. In yet another example,
a variable pressure therapy (e.g., Expiratory Pressure Relief (EPR)
or bi-level pressure, or servo-ventilation bi-level (pressure
support) modes such as ASV, ASV Auto or iVAPS) may be used in
combination with a fixed or a variable flow rate. A variable
pressure and variable flow rate may vary based on characteristics
of the patient's breathing, thereby facilitating the breathing
process.
[0203] The control of the flow of air between CT device 4000 and
the patient may be modelled as an electrical circuit 2700, as shown
in FIG. 27. The positive airway pressure (PAP) device shown may be
pressure device 4140 described above, while the deadspace therapy
(DST) device may be flow device 4141. The PAP device and the DST
device may be incorporated into a single housing such as the
housing 4010 of a CT device 4000, or may exist as separate
units.
[0204] As shown in FIG. 27, air flows from the output of the PAP
device at a flow rate Q1, and air flows from the output of the DST
device at a flow rate Q2. The resistance R1 represents the
resistance of air flow that may exist in the pneumatic path from
the output of the PAP device to the plenum chamber 3200 of the
patient interface 3000. For example, R1 may include the resistance
of air flow along air circuit 4170. The resistance R2 represents
the resistance of air flow that may exist in the pneumatic path
from the output of the DST device to the end of the prongs or
projections. For example, R2 may include the resistance of air flow
along projection conduit 17170. The resistance Rnose represents the
resistance of air flow from the end of the prongs or projections
within the patient's nose back out the nares to the plenum chamber
3200 of the patient interface 3000. The flow whose flow rate is
represented by Q2 is a flushing flow for both anatomical and
mechanical deadspace (i.e. deadspace due to the patient interface),
so Q2 is referred to as the flushing flow rate.
[0205] The pressure of the air at the output of the PAP device is
represented as Pd. The pressure of the air at the end of the prongs
or projections within the patient's nose is represented as Pnose.
The pressure Pm represents the air pressure within the plenum
chamber 3200 of the patient interface 3000. Air may flow out of the
patient interface 3000 through a fixed or adjustable vent, such as
vent 3400. The flow rate through the vent is represented as Qvent.
The vent flow rate Qvent may correspond to the interface pressure
Pm. Accordingly, Qvent may be represented as a function of Pm
through the notation Qvent(Pm). The flow rate of air to the patient
(the respiratory flow rate) is represented by Qr, with the
resistance of air flow through the patient's airways being
represented by Rairway. Air will flow in and out of the patient's
lungs serving as an alternating pressure source during the
patient's breathing cycle. Plungs is therefore shown as an
alternating pressure source, with Clungs representing the elastic
response of the patient's lungs to the air flow being provided at
the patient interface.
[0206] From the topology of the model 2700, it may be shown that
the sum of the PAP and DST flow rates Q1 and Q2 is equal to the sum
of the respiratory flow rate Qr and the vent flow rate Qvent:
Q1+Q2=Qvent(Pm)+Qr
[0207] Because the average respiratory flow rate Qr over many
breathing cycles is zero, the average or DC component of the vent
flow rate Qvent, which may be referred to as the "bias flow rate",
is the sum of the average or DC components of Q1 and Q2.
[0208] The PAP and DST devices of the model 2700 may be controlled
so as to manage both the pressure and flow rate of air in the
system, which may be achieved by control changes of the flow
generators of the PAP and/or DST devices, and optionally in
conjunction with controlling mechanical variations of the opening
size of the vent. In general, the interface pressure Pm and the
deadspace flushing flow rate Q2 may be controlled independently by
respective control of the PAP and DST devices. In particular, the
PAP device may maintain a given interface pressure Pm by setting
its own output pressure Pd to compensate for the known pressure
drop through the resistance R1 at any given flow rate Q1. However,
in order to maintain this control it is beneficial to maintain a
positive flow rate Q1 from the PAP device, to ensure the device
pressure Pd is greater than the interface pressure Pm. To keep Q1
positive, the flushing flow rate Q2 may be controlled so that
throughout the patient's breathing cycle the following is true:
Q2<Qvent(Pm)+Qr
[0209] During expiration, the respiratory flow rate Qr is negative,
so by controlling Q2 to be less than Qvent minus the peak
expiratory flow rate Qe(peak), Q1 may be kept positive throughout
the breathing cycle. In other words, the maximum flushing flow rate
Q2(max) is Qvent(Pm)-Qe(peak). Since in general a lower pressure Pm
means a lower vent flow rate Qvent, a lower pressure Pm means a
lower ceiling on the flushing flow rate Q2. As long as the flushing
flow rate is less than Q2(max), the positive flow Q1 from the PAP
device makes up the difference between Q2 and Qvent+Qr. Q1
therefore oscillates around a steady state value of Qvent-Q2 in
synchrony with the breathing cycle, rising during inspiration and
falling during expiration.
[0210] In this way, the desired flushing of deadspace, such as the
flushing of carbon dioxide from the patient's anatomical deadspace,
may be accomplished through control of the vent pressure/flow
characteristic. For example, for a given interface pressure Pm, an
adjustment to the vent to allow a higher vent flow rate Qvent(Pm)
allows a higher deadspace flushing flow rate Q2.
[0211] The vent flow rate, Qvent, may approximate a quadratic
relationship with the patient interface pressure Pm, such that:
Pm=(A*Qvent.sup.2)+(B*Qvent)
[0212] The terms "A" and "B" are values that may be based on one or
more parameters of the vent. These parameters may be adjusted so as
to alter the relationship between Qvent and Pm such as when the
opening size of an active proximal valve (APV) serving as the vent
3400 is controlled to change. An example APV is disclosed in PCT
Publication no. WO 2010/141983, the entire disclosure of which is
incorporated herein by reference.
[0213] For example, in some cases, changing treatment may require
changing of venting characteristics associated with the patient
interface. Thus, in some cases, such as when a pressure therapy is
being provided with the naris pillows and a CT device, it may
thereafter become desirable to initiate a flow therapy with the
nasal projections, such as providing a flow of supplemental oxygen
or high flow therapy. This change in treatment, which may be
processor activated in the case of a common apparatus or manually
initiated such as in the case of multiple supply devices, may
require an adjustment to a venting characteristic of the patient
interface. For example, a manual vent may be opened or opened more
so as to compensate for the increased flow of gas to the patient's
nares. Alternatively, in the case of an adjustable vent, a
processor may control opening of the vent or opening it more upon
activation of the additional flow to the nasal projections. Similar
vent control may be initiated upon application of a mask over a
cannula such as in the illustration of FIGS. 7, 10, 12 and 13. In
the case of termination of such an additional therapy, the venting
characteristics may be changed again, such as by manually closing
or reducing a vent size or by controlling with a controller a
closing or reduction in the vent size of an
automatic/electro-mechanical vent (e.g., an active proximal
valve).
[0214] The therapy device controller 4240 may control the device
pressure Pd of the pressure device 4140 to deliver a desired or
target interface pressure Pm such as for controlling a generally
constant (with respect to breathing cycle) pressure therapy,
without needing to know the flushing flow rate Q2 being delivered
by the flow device 4141. In such a case, the therapy device
controller 4240 may use conventional methods of leak estimation and
compensation. Under such an approach, the therapy device controller
4240 may effectively treat the flushing flow as a large, constant,
negative leak flow that may be estimated and compensated for such
as when estimating patient flow and/or adjusting pressure to
counter undesired pressure swings induced by patient respiration.
Similarly, to deliver a bi-level pressure therapy, the therapy
device controller 4240 may control the device pressure Pd of the
pressure device 4140 to synchronise the mask pressure Pm with the
patient's breathing cycle without needing to know the flushing flow
rate Q2. Under such an approach, the therapy device controller 4240
may use conventional leak estimation and compensation methods to
estimate the respiratory flow rate Qr, effectively treating the
flushing flow as a large, constant, negative leak flow. The therapy
device controller may then apply conventional triggering and
cycling processing to the respiratory flow rate Qr to determine
when to switch the desired interface pressure Pm from inspiration
to expiration and back.
[0215] However, it may be advantageous for the therapy device
controller 4240 to account explicitly for the flushing flow rate Q2
for either or both of controlling the interface pressure Pm and
estimating the respiratory flow rate Qr for triggering and cycling
purposes.
[0216] Likewise, it may be advantageous for the therapy device
controller 4240 to use the sensed device pressure Pd from the
pressure sensor 4274 in order to compute the interface pressure Pm
and hence the maximum flushing flow rate Q2(max), namely
Qvent(Pm)-Qe(peak), to ensure the flushing flow rate does not
exceed this upper limit.
[0217] In implementations in which the pressure device 4140 and the
flow device 4141 are under the control of a common therapy device
controller 4240, as in FIG. 26, the controller 4240 is aware of all
the system variables such as the device pressure Pd and the
flushing flow rate Q2 (such as with sensed values for the
variables), and can therefore control the pressure device 4140, the
flow device 4141, and optionally an adjustable vent 3400 to deliver
a desired interface pressure Pm and flushing flow rate Q2 in
accordance with the above description.
[0218] However, in implementations in which the pressure device
4140 and the flow device 4141 are under the control of separate
controllers, the pressure device controller may obtain the flushing
flow rate Q2, either by direct communication with the flow rate
transducer 4272, or through communication with the flow device
controller. Likewise, the flow device controller may obtain the
device pressure Pd either by direct communication with the pressure
transducer 4274, or through communication with the pressure device
controller.
[0219] 7.6.1 Single Flow Generator Examples
[0220] In some implementations, a single flow generator may be used
to supply both the flushing flow rate of gas through one or more of
the nasal projections or prongs and the air pressure within the
patient interface 3000. In one such implementation, the air circuit
4170 is not used, the connection port 3600 is blocked, and
projection conduit 17170 may be connected to the output of a single
blower 4142, as shown in FIG. 28. In such an implementation, which
may be modelled by the circuit model 2700 without the PAP device or
the resistance R1, the flow rate Q1 is identically zero, so for any
given venting characteristic Qvent(Pm), the vent flow rate Qvent
will oscillate in synchrony with the breathing cycle around the
flushing flow rate Q2, rising to Q2+Qe at peak expiration, and
falling to Q2-Qi at peak inspiration, as illustrated in FIG. 30.
The interface pressure Pm will also oscillate along the venting
characteristic around a steady state pressure Pm0 such that
Qvent(Pm0) equals the flushing flow rate Q2, falling during
inspiration to a trough pressure Pmi and rising during expiration
to a peak pressure Pme. Such oscillation in interface pressure may
not be desirable and may be minimised by adjusting the venting
characteristic in synchrony with the patient's breathing cycle. For
example, as illustrated in FIG. 31, to maintain a constant
interface pressure Pm0 at a given flushing flow rate Q2, the
parameters of the venting characteristic may be continually
adjusted in synchrony with the patient's breathing cycle so that
the venting characteristic follows the curve VC-E during
expiration, causing Qvent(Pm0) to rise to Q2+Qe and follows the
curve VC-I during inspiration, causing Qvent(Pm0) to fall to
Q2-Qi.
[0221] Similar continuous adjustments to the venting characteristic
may also be made to maintain a constant interface pressure Pm
throughout the breathing cycle in an implementation with no DST
device, so that Q2 is identically zero. In such an implementation,
for any given PAP device pressure Pd, resistance R1, venting
characteristic Qvent(Pm), and respiratory flow rate Qr, the
interface pressure Pm satisfies the equation
Pd-Pm/R1=Qvent(Pm)+Qr
[0222] Continual adjustments to the venting characteristic, or to
the device pressure Pd, in synchrony with the breathing cycle allow
Pm to be maintained at its steady state value (i.e. its value when
Qr is zero) as Qr varies over the breathing cycle.
[0223] Accordingly, in such single-flow-generator implementations,
the interface pressure Pm and flushing flow rate Q2 may be
simultaneously and independently controlled by varying one or more
parameters of the vent 3400 so that a predetermined pressure and
predetermined flushing flow rate are maintained at patient
interface 3000 throughout the breathing cycle. Further, this
configuration allows for control of both Pm and Q2 to arbitrary
patterns with respect to time and the patient's respiration. For
example, a bi-level pressure waveform for Pm where the inspiratory
pressure is higher than the expiratory pressure while Q2 is also
controlled to vary based on aspects of the patient's breathing.
Other examples include Pm of pressure therapy modes of CPAP, APAP,
APAP with EPR, ASV, ST, and iVAPS combined with a Q2 of flow
therapy modes such as fixed flow rate, flow rate varying on the
patient's state of inspiration or expiration, or other ventilation
parameters such as relative hyperventilation or hypoventilation
with respect to the ventilation mean.
[0224] In another single flow generator implementation in which
there is no separate DST device, the output of the PAP device is
connected to both the air circuit 4170 and the projection conduit
17170. Such an implementation may be modelled by the electrical
circuit model 2700a illustrated in FIG. 33. Independent control of
the interface pressure Pm and the flushing flow rate Q2 to their
respective target values throughout the breathing cycle may be
enabled by adjusting the vent characteristic in synchrony with the
breathing cycle as described above. Alternatively, or additionally,
independent control of the interface pressure Pm and the flushing
flow rate Q2 to their respective target values throughout the
breathing cycle may be enabled by adjusting the device pressure Pd
in synchrony with the breathing cycle. Alternatively, or
additionally, the resistance of the air circuit 4170 may be made
variable, e.g. by adding a variable resistance (e.g., a
proportional valve) in the air circuit 4170. Independent control of
the interface pressure Pm and the flushing flow rate Q2 to their
respective target values throughout the breathing cycle may be
enabled by adjusting the resistance of the variable resistance in
the air circuit 4170 in synchrony with the breathing cycle.
[0225] 7.6.2 Nasal Interface Examples
[0226] Various flow path strategies may be implemented to wash out
exhaled carbon dioxide given such different therapies and the
different configurations of the nasal interface when controlled in
conjunction with any of the aforementioned pressure control
regimes. These may be considered with reference to the flow arrows
F of the figures. In the example of FIG. 15A, either an inspiratory
flow (i.e., cyclical supply activation) or a continuous flow may be
supplied toward the patient nasal cavity via both of the nasal
projections 16100 that may be inhaled by the patient during
inspiration. The distal ends (DE) of the nasal projections may be
coupled with further supply conduits such as that illustrated in
FIG. 16. Expiratory gases may be exhausted from the patient nasal
cavities into the passage of the naris pillows and out through any
one or more of the optional base vent 16220 and/or pillow vent(s)
18220. The control of a continuous exhaust flow via such vents
during both inspiration and expiration can assist in ensuring
washout of expiratory gases from the nasal cavities.
[0227] In the example of FIG. 15B, either an inspiratory flow
(i.e., cyclical supply activation) or a continuous flow is supplied
toward the patient nasal cavity via one of the nasal projections
16100 that may be inhaled by the patient during inspiration. In
this example, although not shown in FIG. 15B, the distal end (DE)
of the nasal projection on the left of the drawing may be coupled
to a further supply conduit and a gas source. This flow supply
nasal projection is shown on the left side of FIG. 15B but may
alternatively be on the right. Expiratory gases may then be
exhausted from the patient nasal cavities via the other nasal
projection 16100 (e.g., shown on the right of the figure). In this
case, the distal end of one nasal projection may omit a further
conduit and serve as a pillow vent at the proximity of the naris
pillow 16010. The control of a continuous exhaust flow via such a
vent during both inspiration and expiration can assist in ensuring
washout of expiratory gases from the nasal cavities.
[0228] In the example of FIGS. 17A and 17B, the presence of dual
nasal projections permits venting and supply via the nasal
projections in each naris. Thus, either an inspiratory flow (i.e.,
cyclical supply activation) or a continuous flow is supplied toward
the patient nasal cavity via one of the nasal projections 16100-2
of each naris pillow that may be inhaled by the patient during
inspiration. In this example, although not shown in FIG. 17B, the
distal end DE of one nasal projection of each naris pillow may be
coupled to a further supply conduit and a gas source. Expiratory
gases may then be exhausted from the patient nasal cavities via the
other nasal projection 16100-1 of each naris. In this case, the
distal end of one nasal projection of each naris may omit a further
conduit and serve as a pillow vent 18220 at the proximity of the
naris pillow 16010. The control of a continuous exhaust flow via
such vents during both inspiration and expiration can assist in
improving washout of expiratory gases (such as carbon dioxide) from
the nasal cavities.
[0229] In some cases, the washout flow path may be implemented with
a unitary nasal projection in each naris pillow. Such an example
may be considered in relation to FIG. 18. In this example, a gas
supply nasal projection is omitted. The unitary nasal projection
16100 in each naris pillow may then serve as a nasal projection
vent, such as by venting as a pillow vent. Thus, either an
inspiratory flow (i.e., cyclical supply activation) or a continuous
flow is supplied toward the patient nasal cavity via each naris
pillow so that it may be inhaled by the patient during inspiration.
In this example, the distal end of the unitary nasal projection
16100 may omit a further conduit and serve as a pillow vent 18220
at the proximity of the naris pillow 16010. The control of a
continuous exhaust flow via such vents during both inspiration and
expiration can assist in ensuring washout of expiratory gases from
the nasal cavities.
[0230] In some cases, the washout flow path may be implemented
without nasal projections. Such an example may be considered in
relation to the nasal pillows of FIGS. 19A and 19B. In this
example, each naris pillow may have a pillow vent for venting
expiratory gases during expiration (See FIG. 19B). The pillow vent
may be open during inspiration and expiration or only open during
expiration. Either an inspiratory flow (i.e., cyclical supply
activation) or a continuous flow is supplied toward the patient
nasal cavity via each naris pillow 16010 so that it may be inhaled
by the patient during inspiration (See FIG. 19A). The control of a
continuous exhaust flow via such vents during both inspiration and
expiration can assist in ensuring washout of expiratory gases from
the nasal cavities. However, in the absence of the nasal projection
there is a marginal increase in the deadspace.
[0231] In the example of FIGS. 20A and 20B, vents at the neck or
base of each naris pillow may be activated by an optional vent
valve 21410. These naris pillows may optionally include any of the
nasal projections previously described. In this version, the vent
valve may be activated by rising pressure associated with the
patient's expiratory cycle so as to permit cyclical venting at the
patient's naris pillow. Thus, as illustrated in FIG. 20A, during
expiration, expiratory gases open the vent valve to expel
expiratory air to atmosphere. At this time, the flow path from the
air circuit 4170 to the naris pillow may be blocked. As illustrated
in FIG. 20B, during inspiration, supply gas from the flow generator
or CT device may close the vent valve. At this time, the flow path
from the air circuit 4170 to the naris pillow may be open.
[0232] In another example of FIGS. 20C and 20D, such valves 21410
may be configured so that only some of the pillow vents 18220 are
closed at any one time. In this arrangement, the valves 21410 may
be configured so that one pillow vent is opened, while the other is
closed. Referring now to FIG. 20C, the pillow vent to the left of
the figure is open, while the pillow vent to the right is closed,
and thus expiratory flow from the patient exits through the open
pillow vent. During inhalation, as shown in FIG. 20D, the flow
generator or CT device delivers a flow of supply gas, which is
delivered to the patient while the pillow vent to the left remains
open, thereby continuously washing out gases which has the effect
of reducing dead space. An alternative arrangement is shown in
FIGS. 20E and 20F, wherein the pillow vent to the left is closed
and the pillow vent to the right is open. In one form, the valves
21410 may be arranged so that they are switchable from a first
arrangement, for example shown in FIGS. 20C and 20D to a second
arrangement for example shown in FIGS. 20E and 20F. For example, in
the case of an electromagnetic operation of the valves, they may be
set to the desired operation by a controller. For example, they may
be alternated on a predetermined or pre-set time cycle. Optionally,
the valves may be manually operated and may be manually switched at
a desired time.
[0233] One advantage of switching from the first to the second
arrangement and thus alternating between the left and right nasal
passages as described above may be that it may improve the
patient's comfort level. For instance, the patient using the
patient interface as shown in FIGS. 20C-20D may experience
discomfort from drying out of the patient's right (left on the
figure) nasal passage, which may be alleviated by changing the
configuration of the patient interface to that shown in FIGS.
20E-20F.
[0234] Optionally, such a valve may be extended into a nasal
projection (e.g. shown in FIG. 21) such that the nasal projection
may serve as both supply and exhaust conduit. In such a case, the
nasal projection may include a valve membrane 22500 that divides
the conduit. The valve membrane 22550 may be flexible and extend
along the nasal projection 16100 from or near the proximal end
toward a vent portion 22510 of the nasal projection. The vent
portion may be proximate to or serve as a pillow vent 18220. The
valve membrane 22550 of the nasal projection may be responsive to
inspiratory and expiratory flow such that it may move (See Arrow M
of FIG. 22) dynamically across the channel of the nasal projection
as illustrated in FIGS. 22, 23A and 23B. The valve membrane may
then dynamically reconfigure the nasal projection as an inspiratory
conduit and expiratory conduit on either side of the membrane. For
example, as shown in FIG. 23A, responsive to patient expiration,
movement of the valve membrane 22550 across the proximal end of the
nasal projection enlarges an expiratory channel portion ECP of the
projection that leads to the vent portion 22510. This movement
thereby reduces an inspiratory channel portion ICP of the nasal
projection that leads to a supply gas source or flow generator.
Similarly, as shown in FIG. 23B, responsive to patient inspiration,
return movement of the valve membrane 22550 across the proximal end
of the nasal projection reduces an expiratory channel portion ECP
of the projection that leads to the vent portion 22510. This
movement thereby expands an inspiratory channel portion ICP of the
nasal projection that leads to a supply gas source or flow
generator.
[0235] Nasal interfaces such as the nasal mask 3000 or the pillows
interface 16002 have an advantage over oro-nasal interfaces in that
they more easily permit the patient to speak and eat while
receiving combination therapy. In addition, when the patient opens
his or her mouth incidentally, for example during sleep, the open
mouth acts as an aperture through which leak may occur. Whether
mouth opening is incidental or purposeful to speak or eat, it would
be helpful for the control of combination therapy to detect such an
occurrence. Mouth leak may be continuous or "valve-like", occurring
intermittently when mouth pressure rises during exhalation. Both
kinds of mouth leak may be detected by estimating and analysing the
respiratory flow rate Qr, for example using the methods described
in PCT Patent Publication no. WO 2012/012835, the entire contents
of which are herein incorporated by cross-reference. If a
continuous mouth leak is detected by the controller, the target
interface pressure Pm may be reduced by the controller, e.g. to
zero, for the duration of the mouth opening, to reduce what is
often the unpleasant sensation of air rushing out the mouth and to
enable the patient to eat or speak more comfortably. However, the
controller may optionally continue to control delivery of the
deadspace therapy throughout any of the detected mouth leak
events.
[0236] In a further implementation, an intentional flow of air out
the mouth may be enabled and controlled by a specially designed
oral appliance to be worn by the patient during therapy, e.g.
during sleep. Such a mouth flow may act as an alternative or
supplementary path to ambient for the flushing flow entering the
nasal cavity. The effect of the oral appliance may be modelled in
the electrical circuit model 2700 of FIG. 27 by a further resistive
element between the nose and ambient, i.e. in parallel with the
airway path on the far right of the model 2700. The presence of
this element, and the mouth flow rate Qmouth through it,
effectively adds Qmouth to the ceiling Q2(max) on the flushing flow
rate Q2 for any given interface pressure Pm.
[0237] 7.6.3 Oro-Nasal Interface Examples
[0238] In another form, an oro-nasal (full-face) mask may comprise
one more flow directors configured to deliver a flow of gas towards
the nares of the user. The flow directors may be connected to, and
receive the flow of gas from a supplemental gas source such as an
oxygen source or a flow generator suitable for HFT. For example,
the patient interface may comprise one or more secondary ports
19100 as shown in FIG. 24 connectable to the supplemental gas
source such as via a supply conduit.
[0239] One example of the flow directors may be one or more tubes
19200 coupled to one or more secondary ports 19100 and located
outside of a naris of a patient to direct the flow of gas as shown
in FIG. 25A. The one or more tubes 19200 may be a separable
component which can be engaged with the frame of the patient
interface (e.g. mask) as shown in FIG. 25A, where the tubes 19200
are engaged within the plenum chamber 3200. In some forms, the one
or more tubes 19200 may be integrally formed with another portion
of the patient interface such as the plenum chamber 3200. The one
or more tubes 19200 may be movably configured relative to the rest
of the patient interface, such as pivotably coupled to the mask as
shown in FIG. 25A, to be able to adjust the direction of the flow
of gas.
[0240] A flow director may further comprise a locating feature to
allow the flow director to remain in place once it has been
adjusted, for example by frictional engagement with the plenum
chamber 3200. Although the arrangement shown in FIG. 25A shows two
such tubes that are fluidly connected to each other, as well as to
the secondary ports 19100, it will be understood that any number of
ports and tubes may be used, as well as any combination of
connections therebetween, analogously with the above descriptions
of nasal projections. In another example, each tube 19200 may be
independently connected to the plenum chamber 3200 using hollow
spherical joints (not shown) which allow a flow of gas
therethrough, while also allowing movements of the tube relative to
the rest of the patient interface. Such a connection may thereby
allow a flow of gas to travel between a secondary port 19100 and
the tube 19200.
[0241] In some cases, a flow director may be in a form of a flow
directing surface 19300 coupled to a secondary port 19100. For
instance, each flow directing surface shown in FIG. 25B may
comprise a curved surface shaped to direct the flow of gas from the
supplemental gas source using the Coanda effect, whereby the flow
"attaches" or conforms to the curved surface and follows its
profile. In some forms, the flow directing surface 19300 may be
movably configured, for example by being rotatably coupled to the
plenum chamber 3200.
[0242] According to another aspect, a flow director or a nasal
projection may comprise a flow element, such as a honeycomb grid
(not shown), to reduce turbulence of the flow, whereby the flow
director produces a more laminar flow than otherwise. Such an
arrangement may be particularly advantageous when used in
conjunction with a flow director, as a laminar flow may be more
focussed in comparison to a turbulent flow as it exits out of an
orifice. Accordingly, use of a flow element may assist in
delivering a greater proportion of the flow of gas to the naris of
the patient, whereas without a flow element, more of the flow of
gas may be lost to the interior of the mask and possibly washed out
through a vent.
[0243] 7.6.4 Example Flow/Pressure Control Methodology
[0244] FIG. 29 shows a flow diagram 2900 in accordance with an
aspect of the disclosed systems and methods. Each block of flow
diagram 2900 may be performed by one or more controllers of a
single device, such as CT device 4000, or by controllers of
multiple devices. Various blocks may be performed simultaneously or
in a different order than shown. In addition, operations or blocks
may be added or removed from the flow diagram and still be in
accordance with aspects of the disclosed technology.
[0245] In block 2902, a controller may identify a predetermined
pressure and a predetermined flow rate of the air to be provided to
a patient interface. As described above, the predetermined pressure
and/or the predetermined flow rate may be constant or variable for
a given period of time, and may be selected based on a desired
therapy or combination of therapies to be provided to the patient.
For example, a bi-level pressure therapy may be selected for which
the predetermined pressure of the air is to be adjusted based on
the patient's inspiration and expiration, while the predetermined
flow rate may be maintained at a constant level in accordance with
a selected form of HFT. In block 2904, a controller may receive a
measurement of the current pressure and the current flow rate, as
measured by a pressure sensor and a flow rate sensor, respectively.
A controller may compare the measured pressure and flow rate with
the predetermined pressure and the predetermined flow rate,
respectively (block 2906). The comparison may include determining
whether the measured pressure and flow rate are at or within an
acceptable range with respect to the predetermined pressure and the
predetermined flow rate. If the measured pressure and flow rate
correspond to the predetermined pressure and flow rate, the
controller may return to block 2904.
[0246] If the measured pressure or flow rate does not correspond to
the predetermined pressure or flow rate, the controller may adjust
the output of one or more flow generators and/or may adjust one or
more parameters of an adjustable vent in a manner described above
(block 2908). For example, the system may include two flow
generators, such as pressure device 4140 and a flow device 4141
described above. If the measured pressure does not correspond to
the predetermined pressure, the controller may adjust the output of
either one or both of the flow generators, so as to bring the
measured pressure into correspondence with the predetermined
pressure. The adjustment to the output of one or both of the flow
generators may be performed so that the measured flow rate
continues to correspond with the predetermined flow rate. In this
way, the pressure and flow rate are simultaneously controlled. The
controller may return to block 2904 until the selected therapy
session is terminated or the device is no longer in use (block
2910).
[0247] 7.6.5 Titration of Combination Therapy
[0248] The optimal parameters (e.g., pressure and flow rate) of
combination therapy, in particular the balance between the two
therapies, i.e. the position on the curve 32030, in combination
therapy will vary from patient to patient. The process of choosing
the therapy parameters for a patient is known as titration. In
general the parameters may be chosen or varied based on the
patient's condition as well as respiratory parameters such as
minute ventilation, respiratory rate, expiratory flow shape, lung
mechanics, deadspace, and expired CO.sub.2. For example, patients
with severe NMD need a predominance of pressure support to assist
in the work of breathing, whereas emphysemic patients may benefit
proportionally more from deadspace therapy. Patients with large
lung volume with low pressure support may indicate high deadspace
and therefore proportionally more benefit from deadspace therapy.
Conversely, high respiratory rate indicating significant
respiratory effort may benefit more from pressure support.
[0249] One form of pressure support therapy known as iVAPS is based
on servo-control of alveolar ventilation by varying pressure
support. In iVAPs, the target level of ventilation is an alveolar
ventilation computed by subtracting anatomical deadspace
ventilation from minute ventilation. The amount of anatomical
deadspace for a given patient is a setting that may be provided to
the servo-controller or estimated from the patient's height. In
combination with deadspace therapy, a controller controlling this
form of pressure support therapy may apply a lower value of
anatomical deadspace than would be expected for the patient without
the deadspace therapy such as by implementing a reduction value
applied to the entered or computed anatomical deadspace information
so that the controller can compute a target ventilation setting for
alveolar ventilation that accounts for the DST. A lower value of
deadspace ventilation will result in an alveolar ventilation that
is closer to the minute ventilation. Hence the controller with such
a calculated ventilation target will control generally lower levels
of pressure support.
[0250] 7.6.6 Cardiac Output Estimation
[0251] The Fick technique estimates cardiac output by estimating
the response in expired CO.sub.2 to a deadspace manoeuvre
(typically a step change in deadspace). The flushing flow rate in
deadspace therapy can be used to effectively manipulate deadspace,
and a measure of ventilation (e.g., minute ventilation or tidal
volume) can be used as a proxy for CO.sub.2 response, particularly
during sleep. Therefore, the Fick technique can be performed in
combination therapy by measuring the change in ventilation (e.g.,
minute ventilation or tidal volume) resulting from a step change in
flushing flow rate. For example, a controller may be implemented to
calculate or generate a cardiac output estimate by controlling a
step change in the flushing flow rate and determining change in a
measure of ventilation (e.g., minute ventilation or tidal volume)
in relation to the step change in accordance with the Fick
technique. Such a process may be automatically initiated (or
periodically) by the controller such as during a sleep session,
such as when sleep has been detected by the controller. The
controller may detect sleep by any known method, such as by any of
the automated methods described in International Patent Application
no. PCT/AU2010/000894 (WO/2011/006199) entitled "Detection of Sleep
Condition", the entire disclosure of which is incorporated herein
by reference.
7.7 Additional Patient Interfaces for Optional Therapies
[0252] Some patients have a need for multiple therapies. For
example, some patients may require supplemental gas therapy. For
example, supplemental oxygen therapy may be delivered to the
patient by use of a nasal cannula where prongs of the cannula
supply the oxygen at the patient's nares. Unlike nasal CPAP, such a
therapy does not typically supply the air at therapeutic
pressure(s) so as to treat events of sleep disordered breathing
such as obstructive apnea or obstructive hypopneas. Supplemental
oxygen therapy may be considered with reference to the illustration
of FIG. 6. The traditional nasal cannula 7002 includes nasal prongs
7004A, 7004B which can supply oxygen at the nares of the patient.
Such nasal prongs do not generally form a seal with the inner or
outer skin surface of the nares. The gas to the nasal prongs may
typically be supplied by one or more gas supply lumens 7006a, 7006b
that are coupled with the nasal cannula 7002. Such tubes may lead
to an oxygen source. Alternatively, in some cases, such a nasal
cannula 7002 may provide a high flow therapy to the nares. Such a
high flow therapy (HFT) may be that described in U.S. Patent
Application Publication No. 2011-0253136 filed as International
Application PCT/AU09/00671 on May 28, 2009, the entire disclosure
of which is incorporated herein by cross reference. In such a case,
the lumen from the nasal cannula leads to a flow generator that
generates the air flow for high flow therapy.
[0253] During delivery of such supplemental gas therapies with a
traditional nasal cannula, it may be desirable to periodically
provide a further therapy, such as a pressurized gas therapy or
positive airway pressure (PAP) therapy that requires a patient
interface to form a pressure seal with the patient's respiratory
system. For example, during oxygen therapy with a traditional nasal
cannula, it may be desirable to provide a patient with a
traditional CPAP therapy when a patient goes to sleep, or
traditional pressure support therapy. These additional therapies
may require a mask such as a nasal mask or oro-nasal (mouth and
nose) mask that may optionally include an adjustable vent. Such an
example may be considered with reference to FIG. 7. When the mask
8008 is applied to the patient over the traditional nasal cannula,
one or more of the components of the nasal cannula may interfere
with the mask's seal forming structure (e.g., cushion 8010) so as
to prevent a good seal with the patient. For example, as shown in
FIG. 7, the lumens 7006a, 7006b may interfere with a cushion 8010
of the mask. This may result in a substantial cannula induced leak
(CIL) at or near the lumen which may prevent the desired therapy
pressure levels from being achieved in the mask. Apparatus and
therapies described herein may be implemented to address such
issues so as to permit simultaneous pressure and flow control.
[0254] 7.7.1 Modified Nasal Cannula Embodiments
[0255] In some implementations of the present technologies, a
modified nasal cannula may be implemented to permit its use with
changing therapy needs. For example, as illustrated in FIG. 8, the
nasal cannula 9002 includes a set of projections (e.g., one or more
prongs 9004a, 9004b). Each projection or prong may extend into a
naris of a user. The projection serves as a conduit to deliver a
flow of gas into the naris of the user. The nasal cannula 9002 will
also typically include one or more coupler extensions 9020a, 9020b.
The coupler extension may serve as a conduit to conduct a flow of
gas from a gas supply line, such as lumen 9012a, 9012b. The coupler
extension may be removably coupleable with a base portion 9022 of
the nasal cannula 9002 and/or the supply line(s) of the cannula.
Alternatively, the coupler extension may be integrated with either
or both.
[0256] Typically, each coupler extension(s) may be configured with
a seat portion 9024a, 9024b. The seat portion may include a contact
surface for another patient interface. For example, the seat
portion can serve as a contact surface for a typical seal forming
structure (e.g., a typical face contact cushion) of a mask so as to
permit a seal there between. Thus, the contact surface of the seat
portion may form a seal with a cushion of a mask. The coupler
extension will also typically include a contact surface for
skin/facial contact with a patient to form a seal there between.
The seat portion can include a surface adapted to minimize or
eliminate a cannula induced leak CIL. In some such cases, it may
include a surface with a sealing bevel 9090. The sealing bevel 9090
may promote sealing between the cushion of the mask and a facial
contact surface. In this way, it may fill a gap that would
otherwise be induced by a traditional nasal cannula structure.
[0257] The sealing bevel of the seat portion may be formed with
various cross sectional profiles to promote sealing. For example,
as illustrated in FIG. 9A, the seat portion 9024 of the coupler
extension may have a generally triangular cross sectional profile.
It may be a triangle, for example an isosceles triangle, with the
mask sealing surface on the sides opposite the base. Thus, the
sides opposite the base may be equal or of different lengths. The
base 9026 may typically be configured as the patient sealing
surface. Other cross sectional profiles may also be implemented.
For example, FIGS. 9B, 9C and 9D show a lentil cross sectional
profile. Thus, as illustrated, the profile may be larger centrally
and the top and bottom surfaces may gradually converge by similar
slopes toward the opposing ends of the profile.
[0258] In some cases, the coupler extension(s) may serve as a
conduit for conducting air between the prongs of the nasal cannula
and lumen. For example, as illustrated in FIGS. 9A, 9B, 9C and 9D,
the seat portion may include one or more channel conduits 10030.
The channel conduits may be employed for directing gas in different
gas flow directions with respect to the nasal cannula, to provide
gas to different prongs and/or to provide different gases etc. For
example, one channel conduit may lead to one prong of the nasal
cannula and another channel conduit, if included, may lead to the
other prong of the nasal cannula. As shown in FIG. 9A and 9C, a
single channel conduit is provided. The single channel conduit is
round and may couple with a tube shaped lumen. However, it may be
other shapes, e.g., rectangular. This channel conduit may lead to
both prongs or one prong when coupled with the nasal cannula. As
shown in FIG. 9B and 9D, a double channel conduit is provided. Each
channel of the double channel conduit may have a round, oval or
other similar profile and may couple with a tube shaped lumen. Each
channel double conduit shown in FIG. 9b is rectangular and may be
divided by a rib divider structure 10032 centrally located within
the coupler extension. Each channel may lead to both prongs or each
channel may lead to a different prong when coupled with the nasal
cannula. Additional channel conduits may also be provided for
example, by providing additional rib dividers.
[0259] As shown in FIG. 10A and 10B, when a mask is placed over the
nasal cannula, such that the nasal cannula will be contained within
the plenum chamber, the mask rests not only on the patient's facial
contact areas but also on the seat portion of the nasal cannula. As
further illustrated in FIG. 10B, the profile of the seat portion
permits a seal between the seal forming structure of the mask so as
to reduce gaps. Thus, the seat portion will typically have a length
L and width W (see, e.g., FIG. 8 or FIG. 14A) adapted to receive
typical mask cushions. The length may be longer than a typical
cushion width. The length may be chosen to ensure seal during
lateral displacement of the mask. A measurement from 0.5 to 3.0
inches may be a suitable length range. For example, an
approximately two inch length may be suitable. The width may vary
depending on the height of the channel conduits and typical
flexibility characteristics of mask cushion materials so as to
ensure a gradual sealing bevel that will avoid gaps.
[0260] The coupler extension may be formed by moulding, such as
with a flexible material. For example, it may be formed of
silicone. Optionally, the outer or end portions may be more rigid
than the central section such as by having a solid cross section.
The greater rigidity at the ends of the cross section may help with
limiting their deformation so as to maintain their shape and avoid
creation of gaps between the mask cushion and facial contact areas
during use. In some versions of the coupler extension additional
materials may be applied such as for improving compliance. For
example, a skin contact surface may include a foam layer or soft
material for improved comfort.
[0261] Although the version of the modified nasal cannula of FIG.
10A includes a single supply line on each side of the cannula
(e.g., left side and right side supply lines), additional supply
lines may be implemented. For example, as illustrated in FIGS. 11
and 12, two lumens are applied or protrude from each coupler
extension. In some such cases, each lumen may be coupled with a
different channel conduit of the coupler extension. In such
arrangements, the lumens may be split above and/or below an ear to
provide a more secure fitment for the patient.
[0262] Optionally, the seat portion of any of the cannula described
herein may include a mask fitment structure, such as a seat ridge.
The ridge can serve as a locating feature to indicate, or control,
a relative position of the mask with respect to the seat portion.
Such a seat ridge 12040 feature is illustrated in FIGS. 11 and 12.
The seat ridge may rise from the surface of the seat portion such
as on an outer area or edge of the seat portion (in a direction
normal to the sagital plane).
[0263] FIG. 13 illustrates another version of the coupler extension
of the present technology. In this version, the width of the seat
portion includes an expansion area EA that expands the seat portion
centrally along its length. Such a variation in the contact surface
of the seat portion may assist in improving the seal between the
seat portion and a mask cushion and/or the comfort of the seal
between the coupler extension and the patient's facial contact
area.
[0264] In some versions of the present technology a coupler
extension 15020 may be formed as an add-on component for a
traditional nasal cannula. Such an add-on coupler extension may be
considered with reference to FIGS. 14A-14C. The add-on coupler
extension 15020 may include one or more groove(s) 15052 for
insertion of a supply line such as a lumen of a cannula. Thus, the
coupler extension with its seat portion and sealing bevel may be
easily applied to or under a lumen of a nasal cannula to reduce
gaps when a mask is applied over the lumen of the traditional
cannula. The coupler extension 15020 may also include any of the
features of the coupler extensions previously described. For
example, as shown in FIGS. 14A, 14B, and 14C it may have various
cross sectional profiles such as triangular profile and lentil
profiles. In the version of FIG. 14C, two grooves 15052 are
provided for insertion of two lumens, such as in the case that the
traditional cannula includes two lumens extending out from one or
both sides of the cannula. Although the figures have illustrated
nasal cannula with two prongs, it will be understood that a nasal
cannula of the present technology may be implemented with one or
more nasal prongs (e.g., two).
[0265] 7.7.2 Modified Nasal Pillow Embodiments
[0266] In some versions of the present technology, a common patient
interface may provide a unitary structure for permitting
application of various therapies. Thus, unlike the prior
embodiments, the use and periodic application of an additional
patient interface for varying therapy may not be necessary.
Moreover, features of such a patient interface may be designed to
minimize dead space.
[0267] One such patient interface example that can be implemented
for periodic application of various therapies, for example an
oxygen therapy and a PAP therapy, may be considered with reference
to FIGS. 15A and 15B. The patient interface 16002 may serve as a
nasal interface. Thus, it may include a set of naris pillows (e.g.,
one or more naris pillow(s) 16010). Each naris pillow may be
flexible and may be configured to form a seal with the naris of a
patient when worn. The naris pillow may have an outer conical
surface 16012 that may engage at a skin periphery of a patient's
naris either internal and/or externally of the nostril. Optionally,
the naris pillow may also have an inner conical portion 16014 in a
nested relationship with the outer conical portion (best seen in
FIG. 17B). A gap may exist between the inner conical portion 16014
and the outer conical surface 16012. Each naris pillow may couple
by a neck 16015 portion to a common base portion 16016. A passage
through the central area of the outer conical portion (and/or inner
conical portion), neck and base portion may serve as a flow path to
and/or from a flow generator of CT device 4000 via an air circuit
4170. The air circuit 4170 may be coupled to the base portion 16016
of the patient interface at a flange 16018 (best seen in FIG. 17B).
Optional base extensions 16020-1, 16020-2 may include connectors
16022-1, 16022-2 for connection of the patient interface with a
stabilizing and positioning structure (e.g., straps or other
headgear.)
[0268] One or both of the naris pillows may also include one or
more nasal projections. Each nasal projection 16100 may be a
conduit to conduct a flow of gas through the nasal projection. The
nasal projection will typically project from the nasal pillow. As
illustrated in FIG. 15A and 15B, the nasal projection may be
configured to extend beyond the seal of the naris pillow (e.g.,
beyond the edge of the outer conical portion) so that it may
project into or extend into the nasal cavity of a patient when used
further than the naris pillow at a proximal end PE. The nasal
projection 16100 may emanate from within the flow passage of the
naris pillow (e.g., extend out of a conical portion). The nasal
projection may optionally adhere to an inside wall of the naris
pillow or other internal passage of the patient interface. In some
cases, the nasal projection may be integrated with or formed with
an inside wall of the naris pillow or other internal passage of the
patient interface. Nevertheless, flow passage of the nasal
projection will be discrete from the flow passage of the naris
pillow. Typically, the length of the extension into a nasal cavity
by the nasal projection may be in a range of about 5 mm to 15
mm.
[0269] Optionally, as shown in the version of FIGS. 15A and 15B,
each nasal projection may extend through a passage of the naris
pillow and a passage of the base portion. At a distal end DE of the
nasal projection, the nasal projection may be removeably coupled to
(or integrated with) a further conduit to a gas supply, such as a
flow generator or supplemental gas source (e.g., an oxygen source).
Alternatively, at a distal end DE of the nasal projection, the
nasal projection may be open to atmosphere, such as to serve as a
vent. In some cases, the distal end DE of the nasal projection may
have a removable cap so as to close the distal end and thereby
prevent flow through the nasal projection. For example, as
illustrated in FIG. 16, a projection conduit 17170-1, 17170-2 may
optionally be coupled to each of the nasal projections. Optionally,
the projection conduits 17170 extend along and are external of the
air circuit 4170. However, these projection conduits may extend
along and are internal of the air circuit 4170 such as when they
extend from the base portion 16016 and through the flange 16018 as
illustrated in FIG. 17B.
[0270] In some versions of the patient interface 16002, one or more
vents may be formed at or from a surface of the patient interface.
In other versions, another component (e.g. an adapter or an air
circuit 4170) including one or more vents may be fluidly coupled to
the patient interface. The vent may serve as a flow passage to vent
expired air from the apparatus. Optionally, such a base vent 16220
may be formed on the base portion 16016 as illustrated in FIG. 15A
so as to vent from the chamber inside the base portion. In some
cases, one or more vents may be formed on the naris pillow, such as
on the neck 16015. In some cases, one or more vents may be formed
on a part of the outer conical surface 16012 such as to vent from
the chamber within the naris pillow portion of the patient
interface. In some cases, such a vent may be a fixed opening with a
known impedance. In some such cases, the vent may provide a known
leak. Optionally, such a vent may be adjustable, such as by a
manual manipulation, so as to increase or decrease an opening size
of the vent. For example, the vent may be adjusted from fully open,
partially open and closed positions, etc. In some cases, the vent
may be an electro-mechanical vent that may be controlled by the
flow generator so as increase or decrease the size of the vent
between various opening and closed positions. Example vents and
control thereof may be considered in reference to International
Patent Application No. PCT/US2012/055148 filed on Sep. 13, 2012 and
PCT Patent Application No. PCT/AU2014/000263 filed on Mar. 14,
2014, the entire disclosures of which are incorporated herein by
reference.
[0271] By way of example, in the patient interface 16002 of FIGS.
17A and 17B, the nasal interface includes multiple nasal
projections 16100 extending from each naris pillow. At least one
such nasal projection may serve as a pillow vent 18220 for example,
at a bottom portion of the outer conical surface of the naris
pillow. In the example, the nasal projections 16100-1 each form a
conduit that lead to atmosphere through the naris pillow from the
nasal cavity of a patient. With such a nasal projection extending
into the nasal cavity, a patient's deadspace can be reduced through
a shortened pathway for expired air (carbon dioxide) to be removed
from the patient's airways. In some such examples, the additional
nasal projections 16100-2 may be coupled with a supplemental gas
source such as an oxygen source or a controlled flow of air as
discussed in more detail herein. Optionally, such nasal projections
of each naris pillow may be formed with a deviating projection
(shown in FIG. 17A at arrows DB). Such a deviation such that they
are further apart at the proximal end when compared to lower
portions can assist with holding the extensions within the nasal
cavity during use. Thus, they may gently ply within a nasal cavity
on opposing sides of the nasal cavity.
7.8 Glossary
[0272] For the purposes of the present technology disclosure, in
certain forms of the present technology, one or more of the
following definitions may apply. In other forms of the present
technology, alternative definitions may apply.
[0273] 7.8.1 General
[0274] Air: In certain forms of the present technology, air may
refer to atmospheric air as well as other breathable gases. For
instance, air supplied to a patient may be atmospheric air or
oxygen, and in other forms of the present technology, air may
comprise atmospheric air supplemented with oxygen.
[0275] Ambient: In certain forms of the present technology, the
term ambient will be taken to mean (i) external of the treatment
system or patient, and (ii) immediately surrounding the treatment
system or patient.
[0276] 7.8.2 Anatomy of the Respiratory System
[0277] Diaphragm: A sheet of muscle that extends across the bottom
of the rib cage. The diaphragm separates the thoracic cavity,
containing the heart, lungs and ribs, from the abdominal cavity. As
the diaphragm contracts the volume of the thoracic cavity increases
and air is drawn into the lungs.
[0278] Larynx: The larynx, or voice box houses the vocal folds and
connects the inferior part of the pharynx (hypopharynx) with the
trachea.
[0279] Lungs: The organs of respiration in humans. The conducting
zone of the lungs contains the trachea, the bronchi, the
bronchioles, and the terminal bronchioles. The respiratory zone
contains the respiratory bronchioles, the alveolar ducts, and the
alveoli.
[0280] Nasal cavity: The nasal cavity (or nasal fossa) is a large
air filled space above and behind the nose in the middle of the
face. The nasal cavity is divided in two by a vertical fin called
the nasal septum. On the sides of the nasal cavity are three
horizontal outgrowths called nasal conchae (singular "concha") or
turbinates. To the front of the nasal cavity is the nose, while the
back blends, via the choanae, into the nasopharynx.
[0281] Pharynx: The part of the throat situated immediately
inferior to (below) the nasal cavity, and superior to the
oesophagus and larynx. The pharynx is conventionally divided into
three sections: the nasopharynx (epipharynx) (the nasal part of the
pharynx), the oropharynx (mesopharynx) (the oral part of the
pharynx), and the laryngopharynx (hypopharynx).
[0282] 7.8.3 Aspects of PAP Devices
[0283] APAP: Automatic Positive Airway Pressure. Positive airway
pressure that is continually adjustable between minimum and maximum
limits, depending on the presence or absence of indications of SDB
events.
[0284] Controller: A device, or portion of a device that adjusts an
output based on an input. For example one form of controller has a
variable that is under control--the control variable--that
constitutes the input to the device. The output of the device is a
function of the current value of the control variable, and a set
point for the variable. A servo-ventilator may include a controller
to provide a ventilation therapy. Such a ventilation therapy has
ventilation as an input, a target ventilation as the set point, and
level of pressure support as an output. Other forms of input may be
one or more of oxygen saturation (SaO.sub.2), partial pressure of
carbon dioxide (PCO.sub.2), movement, a signal from a
photoplethysmogram, and peak flow. The set point of the controller
may be one or more of fixed, variable or learned. For example, the
set point in a ventilator may be a long term average of the
measured ventilation of a patient. Another ventilator may have a
ventilation set point that changes with time. A pressure controller
may be configured to control a blower or pump to deliver air at a
particular pressure. A flow controller may be configured to control
a blower or other gas source to deliver air at a particular flow
rate.
[0285] Therapy: Therapy in the present context may be one or more
of positive pressure therapy, oxygen therapy, carbon dioxide
therapy, deadspace therapy, and the administration of a drug.
[0286] 7.8.4 Terms for Ventilators
[0287] Adaptive Servo-Ventilator: A ventilator that has a
changeable, rather than fixed target ventilation. The changeable
target ventilation may be learned from some characteristic of the
patient, for example, a respiratory characteristic of the
patient.
[0288] Backup rate: A parameter of a ventilator that establishes
the minimum respiration rate (typically in number of breaths per
minute) that the ventilator will deliver to the patient, if not
otherwise triggered.
[0289] Cycled: The termination of a ventilator's inspiratory phase.
When a ventilator delivers a breath to a spontaneously breathing
patient, at the end of the inspiratory portion of the breathing
cycle, the ventilator is said to be cycled to stop delivering the
breath.
[0290] Pressure support: A number for a ventilation therapy that is
indicative of the increase in pressure during ventilator
inspiration over that during ventilator expiration, and generally
means the difference in pressure between the maximum value during
inspiration and the minimum value during expiration (e.g.,
PS=IPAP-EPAP). In some contexts pressure support means the
difference which the ventilator aims to achieve, rather than what
it actually achieves.
[0291] Servo-ventilator: A ventilator that provides a ventilation
therapy for which the device measures patient ventilation, has a
target ventilation, and which adjusts the level of pressure support
to bring the patient ventilation towards the target
ventilation.
[0292] Spontaneous/Timed (S/T)--A mode of a ventilator or other
device that attempts to detect the initiation of a breath of a
spontaneously breathing patient. If however, the device is unable
to detect a breath within a predetermined period of time, the
device will automatically initiate delivery of the breath.
[0293] Triggered: When a ventilator delivers a breath of air to a
spontaneously breathing patient, it is said to be triggered to do
so at the initiation of the respiratory portion of the breathing
cycle by the patient's efforts.
[0294] Ventilation: A volumetric measure of gas being exchanged by
the patient's respiratory system, such as a tidal volume. Measures
of ventilation may include one or both of inspiratory and
expiratory flow, per unit time. When expressed as a volume per
minute, this quantity is often referred to as "minute ventilation".
Minute ventilation is sometimes given simply as a volume,
understood to be the volume per minute. A ventilation therapy can
provide a volume of gas for patient respiration so as to perform
some of the work of breathing.
[0295] Ventilator: A mechanical device that provides pressure
support to a patient to perform some or all of the work of
breathing.
7.9 Other Remarks
[0296] A portion of the disclosure of this patent document contains
material which is subject to copyright protection. The copyright
owner has no objection to the facsimile reproduction by anyone of
the patent document or the patent disclosure, as it appears in the
Patent and Trademark Office patent file or records, but otherwise
reserves all copyright rights whatsoever.
[0297] Unless the context clearly dictates otherwise and where a
range of values is provided, it is understood that each intervening
value, to the tenth of the unit of the lower limit, between the
upper and lower limit of that range, and any other stated or
intervening value in that stated range is encompassed within the
technology. The upper and lower limits of these intervening ranges,
which may be independently included in the intervening ranges, are
also encompassed within the technology, subject to any specifically
excluded limit in the stated range. Where the stated range includes
one or both of the limits, ranges excluding either or both of those
included limits are also included in the technology.
[0298] Furthermore, where a value or values are stated herein as
being implemented as part of the technology, it is understood that
such values may be approximated, unless otherwise stated, and such
values may be utilized to any suitable significant digit to the
extent that a practical technical implementation may permit or
require it.
[0299] Unless defined otherwise, all technical and scientific terms
used herein have the same meaning as commonly understood by one of
ordinary skill in the art to which this technology belongs.
Although any methods and materials similar or equivalent to those
described herein can also be used in the practice or testing of the
present technology, a limited number of the exemplary methods and
materials are described herein.
[0300] When a particular material is identified as being preferably
used to construct a component, obvious alternative materials with
similar properties may be used as a substitute. Furthermore, unless
specified to the contrary, any and all components herein described
are understood to be capable of being manufactured and, as such,
may be manufactured together or separately.
[0301] It must be noted that as used herein and in the appended
claims, the singular forms "a", "an", and "the" include their
plural equivalents, unless the context clearly dictates
otherwise.
[0302] All publications mentioned herein are incorporated by
reference to disclose and describe the methods and/or materials
which are the subject of those publications. The publications
discussed herein are provided solely for their disclosure prior to
the filing date of the present application. Nothing herein is to be
construed as an admission that the present technology is not
entitled to antedate such publication by virtue of prior invention.
Further, the dates of publication provided may be different from
the actual publication dates, which may need to be independently
confirmed.
[0303] Moreover, in interpreting the disclosure, all terms should
be interpreted in the broadest reasonable manner consistent with
the context. In particular, the terms "comprises" and "comprising"
should be interpreted as referring to elements, components, or
steps in a non-exclusive manner, indicating that the referenced
elements, components, or steps may be present, or utilized, or
combined with other elements, components, or steps that are not
expressly referenced.
[0304] The subject headings used in the detailed description are
included only for the ease of reference of the reader and should
not be used to limit the subject matter found throughout the
disclosure or the claims. The subject headings should not be used
in construing the scope of the claims or the claim limitations.
[0305] Although the technology herein may have been described with
reference to particular embodiments, it is to be understood that
these embodiments are merely illustrative of the principles and
applications of the technology. In some instances, the terminology
and symbols may imply specific details that are not required to
practice the technology. For example, although the terms "first"
and "second" may be used, unless otherwise specified, they are not
intended to indicate any order but may be utilised to distinguish
between distinct elements. Furthermore, although process steps in
the methodologies may be described or illustrated in an order, such
an ordering is not required. Those skilled in the art will
recognize that such ordering may be modified and/or aspects thereof
may be conducted concurrently or even synchronously.
[0306] It is therefore to be understood that numerous modifications
may be made to the illustrative embodiments and that other
arrangements may be devised without departing from the spirit and
scope of the technology.
* * * * *