U.S. patent application number 14/157360 was filed with the patent office on 2014-05-15 for ventilator-initiated prompt regarding detection of double triggering during ventilation.
This patent application is currently assigned to COVIDIEN LP. The applicant listed for this patent is COVIDIEN LP. Invention is credited to Peter R. Doyle, Kirk Hensley, Gardner Kimm, Gary Milne.
Application Number | 20140130798 14/157360 |
Document ID | / |
Family ID | 45420945 |
Filed Date | 2014-05-15 |
United States Patent
Application |
20140130798 |
Kind Code |
A1 |
Milne; Gary ; et
al. |
May 15, 2014 |
VENTILATOR-INITIATED PROMPT REGARDING DETECTION OF DOUBLE
TRIGGERING DURING VENTILATION
Abstract
This disclosure describes systems and methods for monitoring and
evaluating ventilatory parameters, analyzing those parameters and
providing useful notifications and recommendations to clinicians.
That is, modern ventilators monitor, evaluate, and graphically
represent multiple ventilatory parameters. However, many clinicians
may not easily recognize data patterns and correlations indicative
of certain patient conditions, changes in patient condition, and/or
effectiveness of ventilatory treatment. Further, clinicians may not
readily determine appropriate ventilatory adjustments that may
address certain patient conditions and/or the effectiveness of
ventilatory treatment. Specifically, clinicians may not readily
detect or recognize the presence of double triggering during
ventilation. According to embodiments, a ventilator may be
configured to monitor and evaluate diverse ventilatory parameters
to detect double triggering and may issue notifications and
recommendations suitable for a patient to the clinician when double
triggering is implicated. The suitable notifications and
recommendations may further be provided in a hierarchical
format.
Inventors: |
Milne; Gary; (Louisville,
CO) ; Hensley; Kirk; (Dublin, OH) ; Doyle;
Peter R.; (Vista, CA) ; Kimm; Gardner;
(Carlsbad, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
COVIDIEN LP |
Boulder |
CO |
US |
|
|
Assignee: |
COVIDIEN LP
Boulder
CO
|
Family ID: |
45420945 |
Appl. No.: |
14/157360 |
Filed: |
January 16, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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12955422 |
Nov 29, 2010 |
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14157360 |
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Current U.S.
Class: |
128/202.22 |
Current CPC
Class: |
A61M 16/04 20130101;
A61M 16/0057 20130101; G16H 50/20 20180101; A61M 16/0875 20130101;
A61M 2205/502 20130101; A61M 16/06 20130101; A61M 2205/505
20130101; G06F 19/00 20130101; A61M 16/0063 20140204; A61M
2016/0021 20130101; A61M 16/026 20170801; A61M 16/0816 20130101;
A61M 2016/0036 20130101; A61M 16/0051 20130101; A61M 2230/43
20130101; A61M 16/0833 20140204; A61M 2016/0027 20130101 |
Class at
Publication: |
128/202.22 |
International
Class: |
A61M 16/00 20060101
A61M016/00; A61M 16/06 20060101 A61M016/06; A61M 16/08 20060101
A61M016/08; A61M 16/04 20060101 A61M016/04 |
Claims
1. A ventilator-implemented method for detecting double triggering
during ventilation of a patient, the method comprising: collecting
data associated with ventilatory parameters; processing the
collected ventilatory parameter data, wherein the step of
processing the collected ventilatory parameter data comprises
deriving ventilatory parameter data from the collected ventilatory
parameter data; analyzing the processed ventilatory parameter data,
wherein the step of analyzing the processed ventilatory parameter
data comprises: receiving at least one predetermined threshold
associated with the processed ventilatory parameter data; and
detecting whether the processed ventilatory parameter data breaches
the received at least one predetermined threshold at a
predetermined frequency; determining that double triggering is
implicated upon detecting that the processed ventilatory data
breaches the received at least one predetermined threshold at the
predetermined frequency; and issuing a smart prompt when the double
triggering is implicated.
2. The method of claim 1, wherein the processed ventilatory
parameter data comprises exhaled tidal volume, and wherein the step
of analyzing of the exhaled tidal volume further comprises:
receiving a predetermined threshold for the exhaled tidal volume,
the predetermined threshold comprising: an exhaled tidal volume
that is less than 10 percent of a delivered tidal volume;
determining the delivered tidal volume; and determining that the
exhaled tidal volume is less than 10 percent of the delivered tidal
volume.
3. The method of claim 1, wherein the processed ventilatory
parameter data comprises an expiratory time (T.sub.E) for a
patient-initiated mandatory breath.
4. The method of claim 3, wherein the step of analyzing the
expiratory time (T.sub.E) for the patient-initiated mandatory
breath comprises: receiving a predetermined threshold for the
expiratory time (T.sub.E) the predetermined threshold comprising:
an expiratory time (T.sub.E) threshold of less than 240 ms;
determining an expiratory time (T.sub.E) for the patient-initiated
mandatory breath; and determining that the expiratory time
(T.sub.E) is less than 240 ms.
5. The method of claim 3, wherein the step of analyzing the
expiratory time (T.sub.E) for the patient-initiated mandatory
breath comprises: receiving a predetermined threshold for the
expiratory time (T.sub.E), the predetermined threshold comprising:
an expiratory time (T.sub.E) threshold of less than 210 ms;
determining an expiratory time (T.sub.E) for the patient-initiated
mandatory breath; and determining that the expiratory time
(T.sub.E) is less than 210 ms.
6. The method of claim 3, wherein the step of analyzing the
expiratory time (T.sub.E) for the patient-initiated mandatory
breath comprises: receiving a predetermined threshold for the
expiratory time (T.sub.E) the predetermined threshold comprising:
an expiratory time (T.sub.E) threshold of less than 190 ms;
determining an expiratory time (T.sub.E) for the patient-initiated
mandatory breath; and determining that the expiratory time
(T.sub.E) is less than 190 ms.
7. The method of claim 1, wherein the processed ventilatory
parameter data comprises a disconnect alarm, and wherein the step
of analyzing of the disconnect alarm comprises: determining that
the disconnect alarm has not been activated.
8. The method of claim 1, further comprising: identifying one or
more ventilatory settings associated with a ventilatory treatment
of the patient; determining an appropriate smart prompt based at
least in part on evaluating the one or more ventilatory settings;
and wherein the issued smart prompt is the appropriate smart
prompt.
9. The method of claim 8, wherein the one or more ventilatory
settings are a ventilation breath type selected from a group of
ventilation breath types of pressure controlled (PC),
volume-targeted-pressure-control (VC+), pressure-support (PS), and
volume-support (VS).
10-22. (canceled)
Description
INTRODUCTION
[0001] A ventilator is a device that mechanically helps patients
breathe by replacing some or all of the muscular effort required to
inflate and deflate the lungs. In recent years, there has been an
accelerated trend towards an integrated clinical environment. That
is, medical devices are becoming increasingly integrated with
communication, computing, and control technologies. As a result,
modern ventilatory equipment has become increasingly complex,
providing for detection and evaluation of a myriad of ventilatory
parameters. However, due to the shear magnitude of available
ventilatory data, many clinicians may not readily assess and
evaluate the diverse ventilatory data to detect certain patient
conditions and/or changes in patient conditions, such as double
triggering. Double triggering is a term that refers to a set of
instances in which a ventilator delivers two breaths in response to
what is, in fact, a single patient effort. For example,
hyperinflation, barotrauma, and/or asynchrony are dangerous
conditions that may be implicated/caused by double triggering.
[0002] Indeed, clinicians and patients may greatly benefit from
ventilator notifications when evaluation of various ventilatory
data is indicative of certain patient conditions, changes in
patient conditions, effectiveness of ventilatory therapy, or
otherwise.
VENTILATOR-INITIATED PROMPT REGARDING DETECTION OF DOUBLE
TRIGGERING DURING VENTILATION OF A PATIENT
[0003] This disclosure describes systems and methods for monitoring
and evaluating ventilatory parameters, analyzing ventilatory data
associated with those parameters, and providing useful
notifications and/or recommendations to clinicians. Modern
ventilators monitor, evaluate, and graphically represent, a myriad
of ventilatory parameters. However, many clinicians may not easily
identify or recognize data patterns and correlations indicative of
certain patient conditions, changes in patient condition, and/or
effectiveness of ventilatory treatment. Further, clinicians may not
readily determine appropriate ventilatory adjustments that may
address certain patient conditions and/or the effectiveness of
ventilatory treatment. Specifically, clinicians may not readily
detect or recognize the presence of double triggering. According to
embodiments, a ventilator may be configured to monitor and evaluate
diverse ventilatory parameters to detect double triggering and may
issue notifications and recommendations suitable for a patient to
the clinician when double triggering is implicated. Double
triggering is a term that refers to a set of instances in which a
ventilator delivers two breaths in response to what is, in fact, a
single patient effort. The suitable notifications and
recommendations may further be provided in a hierarchical format
such that the clinician may selectively access summarized and/or
detailed information regarding the presence of double triggering.
In more automated systems, recommendations may be automatically
implemented.
[0004] According to embodiments, ventilator-implemented methods for
detecting double triggering are provided. The methods include
collecting data associated with ventilatory parameters and
processing the collected ventilatory parameter data, wherein
processing the collected ventilatory parameter data includes
deriving ventilatory parameter data from the collected ventilatory
parameter data. The methods also include analyzing the processed
ventilatory parameter data, which includes receiving one or more
predetermined thresholds associated with the processed ventilatory
parameter data and detecting whether the processed ventilatory
parameter data breaches the one or more predetermined thresholds.
The methods include determining that double triggering is
implicated upon detecting that the processed ventilatory data
breaches the one or more predetermined thresholds for more than a
percentage of the patient-initiated mandatory breaths (e.g. 10% or
30%) within a predetermined amount of time or that the processed
ventilatory data breaches the one or more predetermined thresholds
for more than a certain number of breaths (e.g., 3 breaths) within
a predetermined amount of time. When double triggering is
implicated, the methods include issuing a smart prompt.
[0005] According to further embodiments, a ventilatory system for
issuing a smart prompt when double triggering is implicated during
ventilation of a patient is provided. An appropriate notification
message and an appropriate recommendation message may be determined
and either or both of the appropriate notification message and the
appropriate recommendation message may be displayed.
[0006] According to further embodiments, a graphical user interface
for displaying one or more smart prompts corresponding to a
detected condition is provided. The graphical user interface
includes at least one window and one or more elements within the at
least one window comprising at least one smart prompt element for
communicating information regarding the detected condition, wherein
the detected condition is double triggering.
[0007] These and various other features as well as advantages which
characterize the systems and methods described herein will be
apparent from a reading of the following detailed description and a
review of the associated drawings. Additional features are set
forth in the description which follows, and in part will be
apparent from the description, or may he learned by practice of the
technology. The benefits and features of the technology will be
realized and attained by the structure particularly pointed out in
the written description and claims hereof as well as the appended
drawings.
[0008] It is to be understood that both the foregoing general
description and the following detailed description are exemplary
and explanatory and are intended to provide further explanation of
the claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] The following drawing figures, which form a part of this
application, are illustrative of described technology and are not
meant to limit the scope of the claims in any manner, which scope
shall be based on the claims appended hereto.
[0010] FIG. 1 is a diagram illustrating an embodiment of an
exemplary ventilator connected to a human patient.
[0011] FIG. 2 is a block-diagram illustrating an embodiment of a
ventilatory system for monitoring and evaluating ventilatory
parameters associated with double triggering.
[0012] FIG. 3 is a flow chart illustrating an embodiment of a
method for detecting an implication of double triggering.
[0013] FIG. 4 is a flow chart illustrating an embodiment of a
method for issuing a smart prompt upon detecting an implication of
double triggering.
[0014] FIG. 5 is an illustration of an embodiment of a graphical
user interface displaying a smart prompt having a notification
message.
[0015] FIG. 6 is an illustration of an embodiment of a graphical
user interface displaying an expanded smart prompt having a
notification message and one or more recommendation messages.
DETAILED DESCRIPTION
[0016] Although the techniques introduced above and discussed in
detail below may be implemented for a variety of medical devices,
the present disclosure will discuss the implementation of these
techniques for use in a mechanical ventilator system. The reader
will understand that the technology described in the context of a
ventilator system could be adapted for use with other therapeutic
equipment for alerting and advising clinicians regarding deleted
patient conditions.
[0017] This disclosure describes systems and methods for monitoring
and evaluating ventilatory parameters, analyzing ventilatory data
associated with those parameters, and providing useful
notifications and/or recommendations to clinicians. Modern
ventilators monitor, evaluate, and graphically represent a myriad
of ventilatory parameters. However, many clinicians may not easily
identify or recognize data patterns and correlations indicative of
certain patient conditions, changes in patient condition, and/or
effectiveness of ventilatory treatment. Further, clinicians may not
readily determine appropriate ventilatory adjustments that may
address certain patient conditions and/or the effectiveness of
ventilatory treatment. Specifically, clinicians may not readily
detect or recognize the presence of double triggering during
ventilation of a patient.
[0018] According to embodiments, a ventilator may be configured to
monitor and evaluate diverse ventilatory parameters to detect
double triggering and may issue suitable notifications and
recommendations to the clinician when double triggering is
implicated. The suitable notifications and recommendations may
further be provided in a hierarchical format such that the
clinician may selectively access summarized and/or detailed
information, regarding the presence of double triggering. In more
automated systems, recommendations may he automatically
implemented.
Ventilator System
[0019] FIG. 1 is a diagram illustrating an embodiment of an
exemplary ventilator 100 connected to a human patient 150.
Ventilator 100 includes a pneumatic system 102 (also referred to as
a pressure generating system 102) for circulating breathing gases
to and from patient 150 via the ventilation tubing system 130,
which couples the patient 150 to the pneumatic system 102 via an
invasive (e.g., endotracheal tube, as shown) or a non-invasive
(e.g., nasal mask) patient interface 180.
[0020] Ventilation tubing system 130 (or patient circuit 130) may
be a two-limb (shown) or a one-limb circuit for carrying gases to
and from the patient 150. In a two-limb embodiment, a fitting,
typically referred to as a "wye-fitting" 170, may be provided to
couple a patient interface 180 (as shown, an endotracheal tube) to
an inspiratory limb 132 and an expiratory limb 134 of the
ventilation tubing system 130.
[0021] Pneumatic system 102 may be configured in a variety of ways.
In the present example, pneumatic system 102 includes an expiratory
module 108 coupled with the expiratory limb 134 and an inspiratory
module 104 coupled with the inspiratory limb 132. Compressor 106 or
other source(s) of pressurized gases (e.g., air, oxygen, and/or
helium) is coupled with inspiratory module 104 to provide a gas
source for ventilatory support via inspiratory limb 132.
[0022] The pneumatic system 102 may include a variety of other
components, including mixing modules, valves, sensors, tubing,
accumulators, filters, etc. Controller 110 is operaratively coupled
with pneumatic system 102, signal measurement and acquisition
systems, and an operator interlace 120 that may enable an operator
to interact with the ventilator 100 (e.g., change ventilator
settings, select operational modes, breath types, view monitored
parameters, etc). Controller 110 may include memory 112, one or
more processors 116, storage 114, and/or other components of the
type commonly found in command and control computing devices. In
the depleted example, operator interlace 120 includes a display 122
that may be touch-sensitive and/or voice-activated, enabling the
display 122 to serve both as an input and output device.
[0023] The memory 112 includes non-transitory, computer-readable
storage media that stores software that is executed by the
processor 116 and which controls the operation of the ventilator
100. In an embodiment, the memory 112 includes one or more
solid-state storage devices such as flash memory chips. In an
alternative embodiment, the memory 112 may be mass storage
connected to the processor 116 through a mass storage controller
(not shown) and a communications bus (not shown). Although the
description of computer-readable media contained herein refers to a
solid-state storage, it should be appreciated by those skilled in
the art that computer-readable storage media can be any available
media that can be accessed by the processor 116. That is,
computer-readable storage media includes non-transitory, volatile
and non-volatile, removable and non-removable media implemented in
any method or technology for storage of information such as
computer-readable instructions, data structures, program modules or
other data. For example, computer-readable storage media includes
RAM, ROM, EPROM, EEPROM, flash memory or other solid state memory
technology, CD-ROM, DVD, or other optical storage, magnetic
cassettes, magnetic tape, magnetic disk storage or other magnetic
storage devices, or any other medium which can be used to store the
desired information and which can be accessed by the computer.
[0024] Communication between components of the ventilatory system
or between the ventilatory system and other therapeutic-equipment
and/or remote monitoring systems may be conducted over a
distributed network, as described further herein, via wired or
wireless means. Further, the present methods may be configured as a
presentation layer built over the TCP/IP protocol. TCP/IP stands
for "Transmission Control Protocol/Internet Protocol" and provides
a basic communication language for many local networks (such as
intranets or extranets) and is the primary communication language
for the Internet. Specifically, TCP/IP is a bi-layer protocol that
allow for the transmission of data over a network. The higher
layer, or TCP layer, divides a message into smaller packets, which
are reassembled by a receiving TCP layer into the original message.
The lower layer, or IP layer, handles addressing and routing of
packets so that they are properly received at a destination.
Ventilator Components
[0025] FIG. 2 is a block-diagram illustrating an embodiment of a
ventilatory system 200 for monitoring and evaluating ventilatory
parameters associated with double triggering.
[0026] Ventilatory system 200 includes a ventilator 202 with its
various modules and components. That is, ventilator 202 may further
include, inter alia, memory 208, one or more processors 206, user
interface 210, and ventilation module 212 (which may further
include an inspiration module 214 and ventilation module 216).
Memory 208 is defined as described above for memory 112. Similarly,
the one or more processors 206 are defined as described above for
one or more processors 116. Processors 206 may further be
configured with a clock whereby elapsed time may be monitored by
the ventilatory system 200.
[0027] The ventilatory system 200 may also include a display module
204 communicatively coupled to ventilator 202. Display module 204
provides various input screens, for receiving clinician input, and
various display screens, for presenting useful information to the
clinician. The display module 204 is configured to communicate with
user interface 210 and may include a graphical user interface
(GUI). The GUI may be an interactive display, e.g., a
touch-sensitive screen or otherwise, and may provide various
windows and elements for receiving input and interface command
operations. Alternatively, other suitable means of communication
with the ventilator 202 may be provided, for instance by a wheel,
keyboard, mouse, or other suitable interactive device. Thus, user
interface 210 may accept commands and input through display module
204. Display module 204 may also provide useful information in the
form of various ventilatory data regarding the physical condition
of a patient and/or a prescribed respiratory treatment. The useful
information may be derived by the ventilator 202, based on data
collected by a data processing module 222, and the useful
information may be displayed to the clinician in the form of
graphs, wave representations, pie graphs, or other suitable forms
of graphic display. For example, one or more smart prompts may be
displayed on the GUI and/or display module 204 upon detection of an
implication of double triggering by the ventilator. Additionally or
alternatively, one or more smart prompts may be communicated to a
remote monitoring system, coupled via any suitable means to the
ventilatory system 200.
Equation of Motion
[0028] Ventilation module 212 may oversee ventilation of a patient
according to prescribed ventilatory settings. By way of general
overview, the basic elements impacting ventilation may be described
by the following ventilatory equation (also known as the Equation
of Motion):
P.sub.m+P.sub.v=V.sub.T/C+R*F
Here, P.sub.m is a measure of muscular effort that is equivalent to
the pressure generated by the muscles of a patient. If the
patient's muscles are inactive, the P.sub.m is equivalent to 0 cm
H.sub.2O. During inspiration, P.sub.v represents the positive
pressure delivered by a ventilator (generally in cm H.sub.2O).
V.sub.T represents the tidal volume delivered, C refers to the
respiratory compliance, R represents the respiratory resistance,
and F represents the gas flow during inspiration (generally in
liters per min (L/m)). Alternatively, during exhalation, the
Equation of Motion may be represented as:
P.sub.a+P.sub.t=V.sub.TE/C+R*F
Here, P.sub.a represents the positive pressure existing in the
lungs (generally in cm H.sub.2O), P.sub.t represents the
transairway pressure, V.sub.TE represents the tidal volume exhaled,
C refers to the respiratory compliance, R represents the
respiratory resistance, and F represents the gas flow during
exhalation (generally in liters per min (L/m)).
Pressure
[0029] For positive pressure ventilation, pressure at the upper
airway opening (e.g., in the patient's mouth) is positive relative
to the pressure at the body's surface (i.e., relative to the
ambient atmospheric pressure to which the patient's body surface is
exposed, about 0 cm H.sub.2O). As such, when P.sub.t is zero, i.e.,
no ventilatory pressure is being delivered, the upper airway
opening pressure will be equal to the ambient pressure (i.e., about
0 cm H.sub.2O). However, when ventilatory pressure is applied, a
pressure gradient is created that allows gases to flow into the
airway and ultimately into the lungs of a patient during
inspiration (or inhalation).
[0030] According to embodiments, additional pressure measurements
may be obtained and evaluated. For example, transairway pressure,
P.sub.t, which refers to the pressure differential or gradient
between the upper airway opening and the alveoli, may also be
determined. P.sub.t may be represented mathematically as:
P.sub.t=P.sub.awo-P.sub.a
Where P.sub.awo refers to the pressure in the upper airway opening,
or mouth, and P.sub.a refers to the pressure within the alveolar
space, or the lungs (as described above). P.sub.t may also be
represented as follows:
P.sub.t=F*R
Where F refers to low and R refers to respiratory resistances, as
described below.
[0031] Additionally, lung pressure or alveolar pressure, P.sub.a
may be measured or derived. For example, P.sub.a may be measured
via a distal pressure transducer or other sensor near the lungs
and/or the diaphragm. Alternatively, P.sub.a may be estimated by
measuring the plateau pressure, P.sub.Plat, via a proximal pressure
transducer or other sensor at or near the airway opening. Plateau
pressure, P.sub.Plat, refers to a slight plateau in pressure that
is observed at the end of inspiration when inspiration is held for
a period of time, sometimes referred to as an inspiratory hold or
pause maneuver, or a breath-hold maneuver. That is, when
inspiration is held, pressure inside the alveoli and mouth are
equal (i.e., no gas flow). However, as a result of muscular
relaxation and elastance of the lungs during the hold period,
forces are exerted on the inflated lungs that create a positive
pressure. This positive pressure is observed as a plateau in the
pressure waveform that is slightly below the peak inspiratory
pressure, P.sub.Peak, prior to initiation of exhalation. As may be
appreciated, for accurate measurement of P.sub.Plat, the patient
should be sedated or non-spontaneous (as muscular effort during the
inspiratory pause may skew the pressure measurement). Upon
determining P.sub.Plat based on the pressure waveform or otherwise,
P.sub.Plat may be used as an estimate of P.sub.a (alveolar
pressure).
Flow and Volume
[0032] Volume refers to the amount of gas delivered to a patient's
lungs, usually in liters (L). Flow refers to a rate of change in
volume over time (F=.DELTA.V/.DELTA.T). Flow is generally expressed
in liters per minute (L/m or lpm) and, depending on whether gases
are flowing into or out of the lungs, flow may be referred to as
inspiratory flow or expiratory flow, respectively. According to
embodiments, the ventilator may control the rate of delivery of
gases to the patient, i.e., inspiratory flow, and may control the
rate of release of gases from the patient, i.e., expiratory
flow.
[0033] As may be appreciated, volume and flow are closely related.
That is, where flow is known or regulated, volume may be derived
based on elapsed time. Indeed, volume may be derived by integrating
the flow waveform. According to embodiments, a tidal volume,
V.sub.T, may be delivered upon reaching a set inspiratory time
(T.sub.I) at set inspiratory flow. Alternatively, set V.sub.T and
set inspiratory flow may determine the amount of time repaired for
inspiration, i.e., T.sub.I.
Respiratory Compliance
[0034] Additional ventilatory parameters that may be measured
and/or derived may include respiratory compliance and respiratory
resistance, which refer to the load against which the patient
and/or the ventilator must work to deliver gases to the lungs.
Respiratory compliance may be interchangeably referred to herein as
compliance. Generally compliance refers to a relative ease with
which something distends and is the inverse of elastance, which
refers to the tendency of something to return to its original form
after being deformed. As related to ventilation, compliance refers
to the lung volume achieved for a given amount of delivered
pressure (C=.DELTA.V/.DELTA.P). Increased compliance may be
detected when the ventilator measures an increased volume relative
to the given amount of delivered pressure. Some lung diseases
(e.g., acute respiratory distress syndrome (ARDS)) may decrease
compliance and, thus, require increased pressure to inflate the
lungs. Alternatively, other lung diseases may increase compliance,
e.g., emphysema, and may require less pressure to inflate the
lungs.
[0035] Additionally or alternatively, static compliance and dynamic
compliance may be calculated. Static compliance, C.sub.S,
represents compliance impacted by elastic recoil at zero flow
(e.g., of the chest wall, patient circuit, and alveoli). As elastic
recoil of the chest wall and patient circuit may remain relatively
constant, static compliance may generally represent compliance as
affected by elastic recoil of the alveoli. As described above,
P.sub.Plat refers to a slight plateau in pressure that is observed
after relaxation of pleural muscles and elastic recoil, i.e.,
representing pressure delivered to overcome elastic forces. As
such, P.sub.Plat provides a basis for estimating C.sub.S as
follows:
C.sub.S=V.sub.T/(P.sub.Plat-EEP)
Where V.sub.T refers to tidal volume, P.sub.Plat refers to plateau
pressure, and EEP refers to end-expiratory pressure, or baseline
pressure (including PEEP and/or Auto-PEEP). Note that proper
calculation of C.sub.S depends on accurate measurement V.sub.T and
P.sub.Plat.
[0036] Dynamic compliance, C.sub.D is measured during airflow and,
as such, is impacted by both elastic recoil and airway resistance.
Peak inspiratory pressure, P.sub.Peak, which represents the highest
pressure measured during inspiration, i.e., pressure delivered to
overcome both elastic and resistive forces to inflate the lungs, is
used to calculate C.sub.D as follows:
C.sub.D=V.sub.T/(P.sub.Peak-EEP)
Where V.sub.T refers to tidal volume, P.sub.Peak refers to peak
inspiratory pressure, and EEP refers to end-expiratory pressure.
According to embodiments, ventilatory data may be more readily
available for trending compliance of non-triggering patients than
of triggering patients.
Respiratory Resistance
[0037] Respiratory resistance refers to frictional forces that
resist airflow, e.g., due to synthetic structures (e.g.,
endotracheal tube, expiratory valve, etc.), anatomical structures
(e.g., bronchial tree, esophagus, etc.), or viscous tissues of the
lungs and adjacent organs. Respiratory resistance may be
interchangeably referred to herein as resistance. Resistance is
highly dependant on the diameter of the airway. That is, a larger
airway diameter entails less resistance and a higher concomitant
flow. Alternatively, a smaller airway diameter entails higher
resistance and a lower concomitant flow. In fact, decreasing the
diameter of the airway results in an exponential increase in
resistance (e.g., two-times reduction of diameter increases
resistance by sixteen times). As may be appreciated, resistance may
also increase due to a restriction of the airway that is the result
of, inter alia, increased secretions, bronchial edema, mucous
plugs, brochospasm, and/or kinking of the patient interface (e.g.,
invasive endotracheal or tracheostomy tubes).
[0038] Airway resistance may further be represented mathematically
as:
R=P.sub.t/F
Where P.sub.t refers to the transairway pressure and F refers to
the flow. That is, P.sub.t refers to the pressure necessary to
overcome resistive forces of the airway. Resistance may be
expressed in centimeters of water per liter per second (i.e., cm
H.sub.2O/L/s).
Pulmonary Time Constant
[0039] As discussed above, compliance refers to the lung volume
achieved for a given amount of delivered pressure
(C=.DELTA.V/.DELTA.P). That is, stated differently, volume
delivered is equivalent to the compliance multiplied by the
delivered pressure (.DELTA.V=C*.DELTA.P). However, as the lungs are
not perfectly elastic, a period of time is needed to deliver the
volume .DELTA.V at pressure .DELTA.P. A pulmonary time constant
.tau., may represent a time necessary to inflate or exhale a given
percentage of the volume at delivered pressure .DELTA.P. The
pulmonary time constant, .tau., may be calculated by multiplying
the respiratory resistance by the respiratory compliance
(.tau.=R*C) for a given patient and .tau. is generally represented
in seconds, s. The pulmonary time constant associated with
exhalation of the given percentage of volume may be termed an
expiratory time constant and the pulmonary time constant associated
with inhalation of the given percentage of volume may be termed an
inspiratory time constant.
[0040] According to some embodiments, when expiratory resistance
data is available, the pulmonary time constant may be calculated by
multiplying expiratory resistance by compliance. According to
alternative embodiments, the pulmonary time constant may be
calculated based on inspiratory resistance and compliance.
According to further embodiments, the expiratory time, T.sub.E,
should be equal to or greater than three (3) pulmonary time
constants to ensure adequate exhalation. That is, for a triggering
patient, T.sub.E (e.g., determined by trending T.sub.E or
otherwise) should be equal to or greater than 3 pulmonary time
constants. For a non-triggering patient, set RR should yield a
T.sub.E that is equal to or greater than 3 pulmonary time
constants.
Normal Resistance and Compliance
[0041] According to embodiments, normal respiratory resistance and
compliance may be determined based on a patient's predicted body
weight (PBW) (or ideal body weight (IBW)). That is, according to a
standardized protocol or otherwise, patient data may be compiled
such that normal respiratory resistance and compliance values
and/or ranges of values may be determined and provided to the
ventilatory system 200. That is, a manufacturer, clinical facility,
clinician, or otherwise, may configure the ventilator with normal
respiratory resistance and compliance values and/or ranges of
values based on PBWs (or IBWs) of a patient population. Thereafter,
during ventilation of a particular patient, respiratory resistance
and compliance data may be trended for the patient and compared to
normal values and/or ranges of values based on the particular
patient's PBW (or IBW). According to embodiments, the ventilator
may give an indication to the clinician regarding whether the
trended respiratory resistance and compliance data of the
particular patient falls into normal ranges. According to some
embodiments, data may be more readily available for trending
resistance and compliance for non-triggering patients than for
triggering patients.
[0042] According to further embodiments, a predicted T.sub.E may be
determined based on a patient's PBW (or IBW). That is, according to
a standardized protocol, or otherwise, patient population data may
be compiled such that predicted T.sub.E values and/or ranges of
values may be determined based on PBWs (or IBWs) of the patient
population and provided to the ventilatory system 200. Actual (or
trended) T.sub.E for a particular patient may then be compared to
the predicted T.sub.E. As noted previously, increased resistance
and/or compliance may result in an actual T.sub.E that is longer
than predicted T.sub.E. However, when actual T.sub.E is consistent
with predicted T.sub.E, this may indicate that resistance and
compliance for the particular patient fall into normal ranges.
[0043] According to further embodiments, a normal pulmonary time
constant, .tau., may be determined based on a patient's PBW (or
IBW). That is, according to a standardized protocol or otherwise,
patient data may be compiled such that normal .tau. values and/or
ranges of values may be determined based on PBWs (or IBWs) of a
patient population and provided to the ventilatory system 200. A
calculated .tau. may be determined for a particular patient by
multiplying resistance by compliance (as described above,
resistance and compliance data may be more readily available for a
non-triggering patient). As the product of resistance and
compliance results in .tau., increased resistance and/or compliance
may result in an elevated .tau. value. However, when the calculated
.tau. value for the particular patient is consistent with the
normal .tau. value, this may indicate that the resistance and
compliance of the particular patient fall into normal ranges.
Inspiration
[0044] Ventilation module 212 may further include an inspiration
module 214 configured to deliver gases to the patient according to
prescribed ventilatory settings. Specifically, inspiration module
214 may correspond to the inspiratory module 104 or may be
otherwise coupled to source(s) of pressurized gases (e.g., air,
oxygen, and/or helium), and may deliver gases to the patient.
Inspiration module 214 may be configured to provide ventilation
according to various ventilatory breath types, e.g., via
volume-targeted, pressure-targeted, or via any other suitable
breath types.
[0045] Volume ventilation, refers to various forms of
volume-targeted ventilation that regulate volume delivery to the
patient. Different types of volume ventilation are available
depending on the specific implementation of volume regulation, for
example, for volume-cycled ventilation, an end of inspiration is
determined based on monitoring the volume delivered to the patient.
Volume ventilation may include volume-control (VC),
volume-targeted-pressure-control (VC+), or volume-support (VS)
breath types. Volume ventilation may be accomplished by setting a
target volume, or prescribed tidal volume, V.sub.T, for delivery to
the patient. According to embodiments, prescribed V.sub.T and
inspiratory time (T.sub.I) may be set during ventilation start-up,
based on the patient's PBW (or IBW). In this case, flow will be
dependent on the prescribed V.sub.T and set T.sub.I. Alternatively,
prescribed V.sub.T and flow may be set and T.sub.I may result.
According to some embodiments, a predicted T.sub.E may be
determined based on normal respiratory and compliance values or
value ranges based on the patient's PBW (or IBW), Additionally, a
respiratory rate (RR) setting, generally in breaths/min, may be
determined and configured. For a non-triggering patient, the set RR
controls the timing for each inspiration. For a triggering patient,
the RR setting applies if the patient stops triggering for some
reason and/or the patient's triggered RR drops below a threshold
level.
[0046] According to embodiments, during volume ventilation, as
volume and flow are regulated by the ventilator, delivered V.sub.T,
flow waveforms (or flow traces), and volume waveforms may be
constant and may not be affected by variations in lung or airway
characteristics (e.g., respiratory compliance and/or respiratory
resistance). Alternatively, pressure readings may fluctuate based
on lung or airway characteristics. According to some embodiments,
the ventilator may control the inspiratory flow and then derive
volume based on the inspiratory flow and elapsed time. For
volume-cycled ventilation, when the derived volume is equal to the
prescribed V.sub.T, the ventilator may initiate exhalation.
[0047] According to alternative embodiments, the inspiration module
214 may provide ventilation via a form of pressure ventilation.
Pressure-targeted breath types may he provided by regulating the
pressure delivered to the patient in various ways. For example,
during pressure-cycled ventilation, an end of inspiration is
determined based on monitoring the pressure delivered to the
patient. Pressure ventilation may include a pressure-support (PS),
a proportional assist (PA), or a pressure-control (PC) breath type,
for example. The proportional assist (PA) breath type provides
pressure in proportion, to the instantaneous patient effort during
spontaneous ventilation and is base on the equation of motion.
Pressure ventilation may also include various forms of bi-level
(BL) pressure ventilation, i.e., pressure ventilation in which the
inspiratory positive airway pressure (IPAP) is higher than the
expiratory positive airway pressure (EPAP). Specifically, pressure
ventilation may be accomplished by setting a target or prescribed
pressure for delivery to the patient. During pressure ventilation,
predicted T.sub.I may be determined based on normal respiratory and
compliance values and on the patient's PBW (or IBW). According to
some embodiments, a predicted T.sub.E may be determined based on
normal respiratory and compliance values and based on the patient's
PBW (or IBW). A respiratory rate (RR) setting may also be
determined and configured. For a non-triggering patient, the set RR
controls the timing for each inspiration. For a triggering patient,
the RR setting applies if the patient stops triggering for some
reason and/or patient triggering drops below a threshold RR
level.
[0048] According to embodiments, during pressure ventilation, the
ventilator may maintain the same pressure waveform at the month,
P.sub.awo, regardless of variations in lung or airway
characteristics, e.g., respiratory compliance and/or respiratory
resistance. However, the volume and flow waveforms may fluctuate
based on lung and airway characteristics. As noted above, pressure
delivered to the upper airway creates a pressure gradient that
enables gases to flow into a patient's lungs. The pressure from
which a ventilator initiates inspiration is termed the
end-expiratory pressure (EEP) or "baseline" pressure. This pressure
may be atmospheric pressure (about 0 cm H.sub.2O), also referred to
zero end-expiratory pressure (ZEEP). However, commonly, the
baseline pressure may be positive, termed positive end-expiratory
pressure (PEEP). Among other things, PEEP may promote higher
oxygenation saturation and/or may prevent alveolar collapse during
exhalation. Under pressure-cycled ventilation, upon delivering the
prescribed pressure the ventilator may initiate exhalation.
[0049] According to still other embodiments, a combination of
volume and pressure ventilation may be delivered to a patient,
e.g., volume-targeted-pressure-control (VC+) breath type. In
particular, VC+ may provide benefits of setting a target V.sub.T,
while also allowing for monitoring variations in flow. As will be
detailed further below, variations in flow may be indicative of
various patient conditions.
Exhalation
[0050] Ventilation module 212 may further include an exhalation
module 216 configured to release gases from the patient's lungs
according to prescribed ventilatory settings. Specifically,
exhalation module 216 may correspond to expiratory module 108 or
may otherwise be associated with and/or controlling an expiratory
valve for releasing gases from the patient. By way of general
overview, a ventilator may initiate exhalation based on lapse of an
inspiratory time setting (T.sub.I) or other cycling criteria set by
the clinician or derived from ventilator settings (e.g., detecting
delivery of prescribed V.sub.T or prescribed pressure based on a
reference trajectory). Upon initiating the expiratory phases
exhalation module 216 may allow the patient to exhale by opening an
expiratory valve. As such, exhalation is passive, and the direction
of airflow, as described above, is governed by the pressure
gradient between the patient's lungs (higher pressure) and the
ambient surface pressure (lower pressure). Although expiratory flow
is passive, it may be regulated by the ventilator based on the size
of the expiratory valve opening.
[0051] Expiratory time (T.sub.E) is the time from the end of
inspiration until the patient triggers for a spontaneously
breathing patient. For a non-triggering patient, it is the time
from the end of inspiration until the next inspiration based on the
set RR. In some cases, however, the time required to return to the
functional residual capacity (FRC) or resting capacity of the lungs
is longer than provided by T.sub.E (e.g., because the patient
triggers prior to fully exhaling or the set RR is too high for a
non-triggering patient). According to embodiments, various
ventilatory settings may be adjusted to better match the time to
reach FRC with the time available to reach FRC. For example,
increasing flow will shorten T.sub.I, thereby increasing the amount
of time available to reach FRC. Alternatively, V.sub.T may be
decreased, resulting in less time required to reach FRC,
[0052] As may be further appreciated, at the point of transition
between inspiration and exhalation, the direction of airflow may
abruptly change from flowing into the lungs to flowing out of the
lungs or vice versa depending on the transition. Stated another
way, inspiratory flow may be measurable in the ventilatory circuit
until P.sub.Peak is reached, at which point flow is zero.
thereafter, upon initiation of exhalation, expiratory flow is
measurable in the ventilatory circuit until the pressure gradient
between the lungs and the body's surface reaches zero (again,
resulting in zero flow). However, in some cases, as will be
described further herein, expiratory flow may still be positive,
i.e., measurable, at the end of exhalation (termed positive
end-expiratory flow or positive EEF). In this case, positive EEF is
an indication that the pressure gradient has not reached zero or,
similarly, that the patient has not completely exhaled. Although a
single occurrence of premature inspiration may not warrant concern,
repeated detection of positive EEF may be indicative of
Auto-PEEP.
Ventilator Synchrony and Patient Triggering
[0053] According to some embodiments, the inspiration module 214
and/or the exhalation module 216 may be configured to synchronize
ventilation with a spontaneously-breathing, or triggering, patient.
That is, the ventilator may be configured to detect patient effort
and may initiate a transition from exhalation to inspiration (or
from inspiration to exhalation) in response. Triggering refers to
the transition from exhalation to inspiration in order to
distinguish it from the transition from inspiration to exhalation
(referred to as cycling). Ventilation systems, depending on their
breath type, may trigger and/or cycle automatically, or in response
to a detection of patient effort, or both.
[0054] Specifically, the ventilator may detect patient effort via a
pressure-monitoring method, a flow-monitoring method, direct or
indirect measurement of nerve impulses, or any other suitable
method. Sensing devices may be either internal or distributed and
may include any suitable sensing device, as described further
herein. In addition, the sensitivity of the ventilator to changes
in pressure and/or flow may be adjusted such that the ventilator
may properly detect the patient effort, i.e., the lower the
pressure or flow change setting the more sensitive the ventilator
may be to patient triggering.
[0055] According to embodiments, a pressure-triggering method may
involve the ventilator monitoring the circuit pressure, as
described above, and detecting a slight drop in circuit pressure.
The slight drop in circuit pressure may indicate that the patient's
respiratory muscles, P.sub.m, are creating a slight negative
pressure gradient between the patient's lungs and the airway
opening in an effort to inspire. The ventilator may interpret the
slight drop in circuit pressure as patient effort and may
consequently initiate inspiration by delivering respiratory
gases.
[0056] Alternatively, the ventilator may detect a flow-triggered
event. Specifically, the ventilator may monitor the circuit flow,
as described above. If the ventilator detects a slight drop in flow
during exhalation, this may indicate, again, that the patient is
attempting to inspire. In this case, the ventilator is detecting a
drop in bias flow (or baseline flow) attributable to a slight
redirection of gases into the patient's lungs (in response to a
slightly negative pressure gradient as discussed above). Bias flow
refers to a constant flow existing in the circuit during exhalation
that enables the ventilator to detect expiratory flow changes and
patient triggering. For example, while gases are generally flowing
out of the patient's lungs during exhalation, a drop in flow may
occur as some gas is redirected and flows into the lungs in
response to the slightly negative pressure gradient between the
patient's lungs and the body's surface. Thus, when the ventilator
detects a slight drop in flow below the bias flow by a
predetermined threshold amount (e.g., 2 L/min below bias flow), it
may interpret the drop as a patient trigger and may consequently
initiate inspiration by delivering respiratory gases.
Volume-Control Breath Type
[0057] In some embodiments, ventilation module 212 may further
include an inspiration module 214 configured to deliver gases to
the patient according to volume-control (VC). The VC breath type
allows a clinician to set a respiratory rate and to select a volume
to be administered to a patient during a mandatory breath. When
using VC, a clinician sets a desired tidal volume, flow wave form
shape, and an inspiratory flow rate or inspiratory time. These
variables determine how much volume of gas is delivered to the
patient and the duration of inspiration during each mandatory
breath inspiratory phase. The mandatory breaths are administered
according to the set respiratory rate.
[0058] For VC, when the delivered volume is equal to the prescribed
tidal volume, the ventilator may initiate exhalation. Exhalation
lasts from the time at which prescribed volume is reached until the
start of the next ventilator mandated inspiration. This expiration
time is determined by the respiratory rate set by the clinician and
any participation above the set rate by the patient. Upon the end
of exhalation, another VC mandatory breath is given to the
patient.
[0059] During VC, delivered volume and flow waveforms may remain
constant and may not be affected by variations in lung or airway
characteristics. Alternatively, pressure readings may fluctuate
based on lung or airway characteristics. According to some
embodiments, the ventilator may control the inspiratory flow and
then derive volume based on the inspiratory flow and elapsed
time.
[0060] In some embodiments, VC may also be delivered to a
triggering patient. When VC is delivered to a triggering patient,
the breath period (i.e. time between breaths) is a function of the
frequency at which the patient is triggering breaths. That is, the
ventilator will trigger the inhalation based upon the respiratory
rate setting or the patient effort. If no patient effort is
detected, the ventilator will deliver another mandatory breath at
the predetermined respiratory rate.
Volume-Targeted-Pressure-Control Breath Type
[0061] In further embodiments, ventilation module 212 may further
include an inspiration module 214 configured to deliver gases to
the patient using a volume-targeted-pressure-control (VC+) breath
type. The VC+ breath type is a combination of volume and pressure
control breath types that may be delivered to a patient as a
mandatory breath. In particular, VC+ may provide the benefits
associated with setting a target tidal volume, while also allowing
for variable flow. Variable flow may he helpful in meeting
inspiratory flow demands for actively breathing patients.
[0062] As may be appreciated, when resistance increases it becomes
more difficult to pass gases into and out of the lungs, decreasing
flow. For example, when a patient is intubated, i.e., having either
an endotracheal or a tracheostomy tube in place, resistance may be
increased as a result of the smaller diameter of the tube over a
patient's natural airway. In addition, increased resistance may be
observed in patients with obstructive disorders, such as COPD,
asthma, etc. Higher resistance may necessitate, inter alia, a
higher inspiratory time setting for delivering a prescribed
pressure or volume of gases, a lower respiratory rate resulting in
a higher expiratory time for complete exhalation of gases.
[0063] Unlike VC, when the set inspiratory time is reached, the
ventilator may initiate expiration. Expiration lasts from the end
of inspiration until the beginning of the next inspiration. For a
non-triggering patient, the expiratory time (T.sub.E) is based on
the respiratory rate set by the clinician. Upon the end of
expiration, another VC+ mandatory breath is given to the
patient.
[0064] By controlling target tidal volume and allowing for variable
flow, VC+ allows a clinician to maintain the volume while allowing
the flow and pressure targets to fluctuate.
Volume-Support Breath Type
[0065] In some embodiments, ventilation module 212 may further
include an inspiration module 214 configured to deliver gases to
the patient according to volume-support (VS) breath type. The VS
breath type is utilized in the present disclosure as a spontaneous
breath. VS is generally used with a triggering (spontaneously
breathing) patient when the patient is ready to be weaned from a
ventilator or when the patient cannot do all of the work of
breathing on his or her own. When the ventilator senses patient
inspiratory effort, the ventilator delivers a set tidal volume
during inspiration. The tidal volume may be set and adjusted by the
clinician. The patient controls the rate, inspiratory flow, and has
some control over the inspiratory time. The ventilator then adjusts
the pressure over several breaths to achieve the set tidal volume.
When the machine senses a decrease in flow, or inspiration time
reaches a predetermined limit, the ventilator determines that
inspiration is ending. When delivered as a spontaneous breath,
expiration in VS lasts from a determination that inspiration is
ending until the ventilator senses a next patient effort to
breath.
Pressure-Control Breath Type
[0066] In additional embodiments, ventilation module 212 may
further include an inspiration module 214 configured to deliver
gases to the patient according to the pressure-control (PC) breath
type. PC allows a clinician to select a pressure to be administered
to a patient during a mandatory breath. When using the PC breath
type, a clinician sets a desired pressure, inspiratory time, and
respiratory rate for a patient. These variables determine the
pressure of the gas delivered to the patient during each mandatory
breath inspiration. The mandatory breaths are administered
according to the set respiratory rate.
[0067] For the PC breath type, when the inspiratory time is equal
to the prescribed inspiratory time, the ventilator may initiate
expiration. Expiration lasts from the end of inspiration until the
next inspiration. Upon the end of expiration, another PC mandatory
breath is given to the patient.
[0068] During PC breaths, the ventilator may maintain the same
pressure waveform at the mouth, regardless of variations in lung or
airway characteristics, e.g., respiratory compliance and/or
respiratory resistance. However, the volume and low waveforms may
fluctuate based on lung and airway characteristics.
[0069] In some embodiments, PC may also be delivered for triggering
patients. When PC is delivered with triggering, the breath period
(i.e., time between breaths) is a function of the respiratory rate
of the patient. The ventilator will trigger the inhalation based
upon the respiratory rate setting or the patient's trigger effort,
but cycling to exhalation will be based upon elapsed inspiratory
time. The inspiratory time is set by the clinician. The inspiratory
flow is delivered based upon the pressure setting and patient
physiology. Should the patient create air expiratory effort in the
middle of the mandatory inspiratory phase, the ventilator will
respond by reducing flow. If no patient effort is detected, the
ventilator will deliver another mandatory breath at the
predetermined respiratory rate.
[0070] PC with triggering overcomes some of the problems
encountered by other mandatory breath types that use artificially
set inspiratory flow rates. For example, if the inspiratory flow is
artificially set lower than a patient's demand, the patient will
feel starved for flow. This can lead to undesirable effects,
including increased work of breathing. In addition, should the
patient begin to exhale when using one of the traditional mandatory
breath types, the patient's expiratory effort is ignored since the
inspiratory flow is mandated by the ventilator settings.
Pressure-Support Breath Type
[0071] In further embodiments, ventilation module 212 may further
include an inspiration module 214 configured to deliver gases to
the patient according to a pressure-support (PS) breath type. PS is
a form of assisted ventilation and is utilized in the present
disclosure during a spontaneous breath. PS is a patient triggered
breath and is typically used when a patient is ready to be weaned
from a ventilator or for when patients are breathing spontaneously
but cannot do all the work of breathing on their own. When the
ventilator senses patient inspiratory effort, the ventilator
provides a constant pressure during inspiration. The pressure may
be set and adjusted by the clinician. The patient controls the
rate, inspiratory flow, and to an extent, the inspiratory time. The
ventilator delivers the set pressure and allows the flow to vary.
When the machine senses a decrease in flow, or determines that
inspiratory time has reached a predetermined limit, the ventilator
determines that inspiration is ending. When delivered as a
spontaneous breath, expiration in PS lasts from a determination
that inspiration is ending until the ventilator senses a patient
effort to breath.
Expiratory Sensitivity
[0072] As discussed above, ventilation module 212 may oversee
ventilation of a patient according to prescribed ventilatory
settings. In one embodiment, the expiratory sensitivity
(E.sub.SENS) is set by a clinician or operator. According to
embodiments, E.sub.SENS sets the percentage of delivered peak
inspiratory flow necessary to terminate inspiration and initiate
exhalation. In some embodiments, the clinician operator determines
the E.sub.SENS setting, which is adjustable from 1% to 80%. A lower
set E.sub.SENS increases inspiration time and a higher set
E.sub.SENS decreases inspiration time. The E.sub.SENS setting may
be utilized to limit unnecessary expiratory work and to improve
patient-ventilator synchrony.
[0073] The ventilatory system 200 may also include one or mote
distributed sensors 218 communicatively coupled to ventilator 202.
Distributed sensors 218 may communicate with various components of
ventilator 202, e.g., ventilation module 212, internal sensors 220,
data processing module 222, double triggering detection module 224,
and any other suitable components and/or modules. Distributed
sensors 218 may detect changes in ventilatory parameters indicative
of double triggering, for example. Distributed sensors 218 may be
placed in any suitable location, e.g., within the ventilatory
circuitry or other devices communicatively coupled to the
ventilator. For example, sensors may be affixed to the ventilatory
tubing or may be imbedded in the tubing itself. According to some
embodiments, sensors may be provided at or near the lungs (or
diaphragm) for detecting a pressure in the lungs. Additionally or
alternatively, sensors may be affixed or imbedded in or near
wye-fitting 170 and/or patient interface 180, as described
above.
[0074] Distributed sensors 218 may further include pressure
transducers that may detect changes in circuit pressure (e.g.,
electromechanical transducers including piezoelectric, variable
capacitance, or strain gauge). Distributed sensors 218 may further
include various flowmeters for detecting airflow (e.g.,
differential pressure pneumotachometers). For example, some
flowmeters may use obstructions to create a pressure decrease
corresponding to the flow across the device (e.g., differential
pressure pneumotachometers) and other flowmeters may use turbines
such that flow may be determined based on the rate of turbine
rotation (e.g., turbine flowmeters). Alternatively, sensors may
utilize optical or ultrasound techniques for measuring changes in
ventilatory parameters. A patient's blood parameters or
concentrations of expired gases may also be monitored by sensors to
detect physiological changes that may be used as indicators to
study physiological effects of ventilation, wherein the results of
such studies may be used for diagnostic or therapeutic purposes.
Indeed, any distributed sensory device useful for monitoring
changes in measurable parameters daring ventilatory treatment may
be employed in accordance with embodiments described herein.
[0075] Ventilator 202 may farther include one or more internal
sensors 220. Similar to distributed sensors 218, internal sensors
220 may communicate with various components of ventilator 202,
e.g., ventilation module 212, internal sensors 220, data processing
module 222, double triggering detection module 224, and any other
suitable components and/or modules. Internal sensors 220 may employ
any suitable sensory or derivative technique for monitoring one or
more parameters associated with the ventilation of a patient.
However, the one or more internal sensors 220 may be placed in any
suitable internal location, such as, within the ventilatory
circuitry or within components or modules of ventilator 202. For
example, sensors may be coupled to the inspiratory and/or
expiratory modules for detecting changes in, for example, circuit
pressure and/or flow. Specifically, internal sensors 220 may
include pressure transducers and flowmeters for measuring changes
in circuit pressure and airflow. Additionally or alternatively,
internal sensors 220 may utilize optical or ultrasound techniques
for measuring changes in ventilatory parameters. For example, a
patient's expired gases may be monitored by internal sensors 220 to
detect physiological changes indicative of the patient's condition
and/or treatment, for example. Indeed, internal sensors 220 may
employ any suitable mechanism for monitoring parameters of interest
in accordance with embodiments described herein.
[0076] As should be appreciated, with reference to the Equation of
Motion, ventilatory parameters are highly interrelated and,
according to embodiments, may be either directly or indirectly
monitored. That is, parameters may be directly monitored by one or
more sensors, as described above, or may be indirectly monitored by
derivation according to the Equation of Motion.
Ventilatory Data
[0077] Ventilator 202 may further include a data processing module
222. As noted above, distributed sensors 218 and internal sensors
220 may collect data regarding various ventilatory parameters. A
ventilatory parameter refers to any factor, characteristic, or
measurement associated with the ventilation of a patient, whether
monitored by the ventilator or by any other device. Sensors may
further transmit collected data to the data processing module 222
and, according to embodiments, the data processing module 222 may
be configured to collect data regarding some ventilatory
parameters, to derive data regarding other ventilatory parameters,
and to graphically represent collected and derived data to the
clinician and/or other modules of the ventilatory system 200. Some
collected, derived, and/or graphically represented data may be
indicative of double triggering. For example, data regarding
expiratory time, exhaled tidal volume, inspiratory time setting
(T.sub.I), etc., may be collected, derived, and/or graphically
represented by data processing module 222.
Flow Data
[0078] For example, according to embodiments, data processing
module 222 may be configured to monitor inspiratory and expiratory
flow. Flow may be measured by any appropriate, internal or
distributed device or sensor within the ventilatory system 200. As
described above, flowmeters may be employed by the ventilatory
system 200 to detect circuit flow. However, any suitable device
either known or developed in the future may be used for detecting
airflow in the ventilatory circuit.
[0079] Data processing module 222 may be further configured to plot
monitored flow data graphically via any suitable means. For
example, according to embodiments, flow data may be plotted versus
time (flow waveform), versus volume (flow-volume loop), or versus
any other suitable parameter as may be useful to a clinician.
According to embodiments, flow may be plotted such that each breath
may be independently identified. Further, flow may be plotted such
that inspiratory flow and expiratory flow may be independently
identified, e.g., inspiratory flow may be represented in one color
and expiratory flow may be represented in another color. According
to additional embodiments, flow waveforms and flow-volume loops,
for example, may be represented alongside additional graphical
representations, e.g., representations of volume, pressure, etc.,
such that clinicians may substantially simultaneously visualize a
variety of ventilatory parameters associated with each breath.
[0080] As may be appreciated, flow decreases as resistance
increases, making it more difficult to pass gases into and out of
the lungs (i.e., F=P.sub.t/R). For example, when a patient is
intubated, i.e., having either an endotracheal or a tracheostomy
tube in place, resistance may be increased as a result of the
smaller diameter of the tube over a patient's natural airway. In
addition, increased resistance may be observed in patients with
obstructive disorders, such as COPD, asthma, etc. Higher resistance
may necessitate, inter alia, a higher inspiratory time setting
(T.sub.I) for delivering a prescribed pressure or volume of gases,
a higher flow setting for delivering prescribed pressure or volume,
a lower respiratory rate resulting in a higher expiratory time
(T.sub.E) for complete exhalation of gases, etc.
[0081] Specifically, changes in flow may be detected by evaluating
various flow data. For example, by evaluating FV loops, as
described above, an increase in resistance may be detected over a
number of breaths. That is, upon comparing consecutive FV loops,
the expiratory plot for each FV loop may reflect a progressive
reduction in expiratory flow (i.e., a smaller FV loop), indicative
of increasing resistance.
Pressure Data
[0082] According to embodiments, data processing module 222 may be
configured to monitor pressure. Pressure may be measured by any
appropriate, internal or distributed device or sensor within the
ventilatory system 200. For example, pressure may be monitored by
proximal electromechanical transducers connected near the airway
opening (e.g., on the inspiratory limb, expiratory limb, attire
patient interface, etc.). Alternatively, pressure may be monitored
distally, at or near the lungs and/or diaphragm of the patient.
[0083] For example, P.sub.Peak and/or P.sub.Plat (estimating
P.sub.a) may be measured proximally (e.g., at or near the airway
opening) via single-point pressure measurements. According to
embodiments, P.sub.Plat (estimating P.sub.a) may be measured during
an inspiratory pause maneuver (e.g., expiratory and inspiratory
valves are closed briefly at the end of inspiration for measuring
the P.sub.Plat at zero flow). According to other embodiments,
circuit pressure may be measured during an expiratory pause
maneuver (e.g., expiratory and inspiratory valves are closed
briefly at the end of exhalation for measuring EEP at zero
flow).
[0084] Data processing module 222 may be further configured to plot
monitored pressure data graphically via any suitable means. For
example, according to embodiments, pressure data may be plotted
versus time (pressure waveform), versus volume (pressure-volume
loop or PV loop), or versus any other suitable parameter as may be
useful to a clinician. According to embodiments, pressure may be
plotted such that each breath may be independently identified.
Further, pressure may be plotted such that inspiratory pressure and
expiratory pressure may be independently identified, e.g.,
inspiratory pressure may be represented in one color and expiratory
pressure may be represented in another color. According to
additional embodiment, pressure waveforms and PV loops, for
example, may be represented alongside additional graphical
representations, e.g., representations of volume, flow, etc., such
that a clinician may substantially simultaneously visualize a
variety of parameters associated with each breath.
[0085] According to embodiment, PV loops may provide useful
clinical and diagnostic information to clinicians regarding the
respiratory resistance or compliance of a patient. Specifically,
upon comparing PV loops from successive breaths, an increase in
resistance may be detected when successive PV loops shorten and
widen over time. That is, at constant pressure, less volume is
delivered to the lungs when resistance is increasing, resulting in
a shorter, wider PV loop. According to alternative embodiments, a
PV loop may provide a visual representation, in the area between
the inspiratory plot of pressure vs. volume and the expiratory plot
of pressure vs. volume, which is indicative of respiratory
compliance. Further, PV loops may be compared to one another to
determine whether compliance has changed. Additionally or
alternatively, optimal compliance may be determined. That is,
optimal compliance may correspond to the dynamic compliance
determined from a PV loop during a recruitment maneuver, for
example.
[0086] According to additional embodiment, PV curves may be used to
compare C.sub.S and C.sub.D over a number of breaths. For example,
a first PV curve may be plotted for C.sub.S (based on P.sub.Plot
less EEP) and a second PV curve may be plotted C.sub.D (based on
P.sub.Peak less EEP). Under normal conditions, C.sub.S and C.sub.D
curves may be very similar, with the C.sub.D curve mimicking the
C.sub.S curve but shifted to the right (i.e., plotted at higher
pressure). However, in some cases the C.sub.D curve may flatten out
and shift to the right relative to the C.sub.S curve. This
graphical representation may illustrate increasing P.sub.t, and
thus increasing R, which may be due to mucous plugging or
bronchospasm, for example. In other cases, both the C.sub.D curve
and C.sub.S curves may flatten out and shift to the right. This
graphical representation may illustrate an increase in P.sub.Peak
and P.sub.Plat, without an increase in P.sub.t, and thus may
implicate a decrease in lung compliance, which may be due to
tension pneumothorax, atelectasis, pulmonary edema, pneumonia,
bronchial intubation, etc.
[0087] As may be further appreciated, relationships between
resistance, static compliance, dynamic compliance, and various
pressure readings may give indications of patient condition. For
example, when C.sub.S increases, C.sub.D increases and, similarly,
when R increases, C.sub.D increases. Additionally, as discussed
previously, P.sub.t represents the difference in pressure
attributable to resistive forces over elastic forces. Thus, where
P.sub.Peak and P.sub.t are increasing with constant V.sub.T
delivery, R is increasing (i.e., where P.sub.Peak is increasing
without a concomitant increase in P.sub.Plat). Where P.sub.t is
roughly constant, but where P.sub.Peak and P.sub.Plat and are
increasing with a constant V.sub.T delivery, C.sub.S is
increasing.
Volume Data
[0088] According to embodiments, data processing module 222 may be
configured to derive volume via any suitable means. For example, as
described above, during volume ventilation, a prescribed V.sub.T
may be set for delivery to the patient. The actual volume delivered
may be derived by monitoring the inspiratory flow over time (i.e.,
V=F*T). Stated differently, integration of flow over time will
yield volume. According to embodiments, V.sub.T is completely
delivered upon reaching T.sub.I. Similarly, the expiratory flow may
be monitored such that expired tidal volume (V.sub.TE) may be
derived. That is, under ordinary conditions, upon reaching the
T.sub.E, the prescribed V.sub.T delivered should be completely
exhaled and FRC should be reached. However, under some conditions
T.sub.E is inadequate for complete exhalation and FRC is not
reached.
[0089] Data processing module 222 may be further configured to plot
derived volume data graphically via any suitable means. For
example, according to embodiments, volume data may be plotted
versus time (volume waveform), versus flow (flow-volume loop or FV
loop), or versus any other suitable parameter as may be useful to a
clinician. According to embodiments, volume may be plotted such
that each breath may be independently identified. Further, volume
may be plotted such that prescribed V.sub.T and V.sub.TE may be
independently identified, e.g., prescribed V.sub.T may be
represented in one color and V.sub.TE may be represented in another
color. According to additional embodiments, volume waveforms and FV
loops, for example, may be represented alongside additional
graphical representations, e.g., representations of pressure, flow,
etc., such that a clinician may substantially simultaneously
visualize a variety of parameters associated with each breath.
[0090] According to embodiments, data processing module 233 may be
configured to determine if the ventilation tubing system 130 or
patient circuit has become disconnected from the patient or the
ventilator during ventilation. Data processing module 222
determines that a patient circuit is disconnected by any suitable
means. In some embodiments, data processing module 222 determines
that the patient circuit is disconnected by evaluating data, such
as exhaled pressure and/or exhaled volume. In further embodiments,
data processing module 222 determines if the patient circuit is
disconnected by determining if a disconnect alarm has been
executed. If the disconnect alarm has been executed, then data
processing module 222 determines that the patient circuit is
disconnected. If the disconnect alarm has not been executed, then
data processing module 222 determines that the patient circuit is
connected.
Breath Type
[0091] According to embodiments, data processing module 232 may be
configured to identify the ventilator breath type. Data processing
module 222 determines the breath type by any suitable means or
methods. In some embodiments, data processing module 222 determines
the breath type based on clinician or operator input and/or
selection. In further embodiments, data processing module 222
determines the breath type based on ventilator selection of the
breath type. For example, some breath, types include VC, PC, VC+,
PS, PA, and VS.
Double Trigger Detection
[0092] Ventilator 202 may further include a double triggering
detection module 224. Double triggering is a term that refers to a
set of instances in which a ventilator delivers two breaths in
response to what is, in fact, a single patient effort. A double
trigger occurs when the ventilator delivers two or more ventilator
cycles separated by a very short expiratory time, with at least one
breath being triggered by the patient. Typically the first cycle is
patient triggered and the second breath is triggered by either a
continuation of the patient's inspiratory effort or from some
anomalous condition that is interpreted by the ventilator as a
second patient effort. Because of the short expiratory time, the
additional breaths may come before the patient has the chance to
fully exhale and may cause gas-trapping in the lungs. Accordingly,
double triggering can lead to patient discomfort and/or an increase
in the length of ventilation time. Further, double triggering can
lead to hyper inflation, barotraumas, hypoxia, and/or
asynchrony.
[0093] Barotrauma may result from the over-distension of alveoli,
which may cause disruption of the alveolar epithelium. Further as
pressure in the alveoli increases, some alveoli may rupture,
allowing gases to seep into the perivascular sheath and into the
mediastinum. This condition may be referred to as pulmonary
interstitial emphysema (PIE). Further complications associated with
PIE may result in Pneumothorax (i.e., partial to complete collapse
of a lung due to gases collected in the pleural cavity).
[0094] Double triggering may result when there is a mismatch
between the ventilation setting for inspiratory time and the
patient's neurological inspiratory time. The patient's neurological
inspiratory time is the amount of time desired by the patient
between breaths. The patient neurological inspiratory time may vary
for every patient and may vary per breath for each patient. Double
triggering may also result when there is mismatch between flow and
set inspiratory time and patient desired flow and neurological
inspiratory time.
[0095] According to embodiments, double triggering may occur as a
result of various patient conditions and/or inappropriate
ventilator settings. Thus, according to embodiments, double
triggering detection module 224 may evaluate various ventilatory
parameter data based on one or more predetermined thresholds to
detect the presence of double triggering. For example, double
triggering detection module 224 may evaluate expiratory time,
exhaled tidal volume, inspiratory time setting (T.sub.I), patient
circuit connection, etc. and compare the evaluated parameters to
one or more predetermined thresholds. In order to prevent
unnecessary alarms, prompts, notifications, and/or recommendations,
thresholds and conditions are utilized by the double triggering
detection module 224 to determine when double triggering has
occurred with sufficient frequency to warrant notification of the
operator. For example, in some embodiments, a double trigger that
occurs in isolation from any other double trigger will not be
considered enough to warrant an occurrence of double triggering by
the double triggering detection module 224. As used herein any
threshold, condition, setting, parameter, or frequency that is
"predetermined" may be input or selected by the operator and/or may
be set or selected by the ventilator.
[0096] In embodiments, the double triggering detection module 224
may detect double triggering when one or more predetermined
thresholds are breached at a predetermined frequency. In some
embodiments, the double triggering detection module 224 may detect
double triggering when one or more predetermined thresholds are
breached at least three times within a predetermined amount of
time. In alternative embodiments, the double triggering detection
module 224 may detect double triggering when one or more
predetermined thresholds are breached by more than 30% of the
patient-initiated mandatory breaths within a predetermined amount
of time. In some embodiments, the double triggering detection
module 224 may detect double triggering when one or more
predetermined thresholds are breached more than 10% of the
patient-initiated mandatory breaths within a predetermined amount
of time. The predetermined amount of time may be any suitable range
of time for determining if double triggering has occurred, such as
any time ranging from 30 seconds to 240 seconds.
[0097] According to some embodiments, double triggering detection
module 224 may detect double triggering when a double trigger has
occurred at least three times within the last 60 seconds. According
to further embodiments, double triggering detection module 224 may
detect double triggering when more than 30% of the
patient-initiated mandatory breaths have a doable trigger within
the last 180 seconds. According to additional embodiments, double
triggering defection module 224 may detect double triggering when
more than 10% of the patient-initiated mandatory breaths have a
double trigger within the last 60 seconds. The double triggering
detection module 224 may begin the evaluation at the beginning of
each patient-initiated breath.
[0098] In some embodiments, double triggering detection module 224
detects a double trigger when one or more of the following
conditions are met: [0099] 1. expiratory time for a
patient-initiated mandatory breath is less than 240 milliseconds
(ms); [0100] 2. the exhaled tidal volume associated with the
expiratory period is less than 10% of the delivered tidal volume of
the prior inspiratory period; and [0101] 3. no disconnect alarm is
detected. In further embodiments, condition number 1, listed above,
may refer to any suitable expiratory time threshold. For example,
in an alternative embodiment the expiratory time threshold is an
expiratory time of less than 230 ms, 220 ms, 210 ms, 200 ms, or 190
ms depending upon the type of ventilator, patient, breath type,
ventilator parameters, ventilator settings, and/or ventilator
modes, etc. Condition number 3 listed above, is considered a
"threshold" in the present disclosure and in the listed claims.
Further, the detection of any yes/no "condition" is considered a
"threshold" in the present disclosure and in the listed claims. In
an embodiment of the double triggering detection system, all three
of the above conditions must be present for the double triggering
detection module 224 to detect a double trigger.
[0102] The three thresholds listed above are just one example list
of possible conditions that could be used to indicate double
triggering. Any suitable list of conditions for determining the
occurrence of double triggering may be utilized. For example, other
suitable conditions/thresholds that may be utilized to determine
that double triggering is implicated include a determination that
the patient circuit has not become disconnected, an analysis of
pressure during exhalation, a comparison of the estimated patient's
neural inspiratory time to inspiratory time delivered by the
ventilator, an analysis of end tidal carbon dioxide (ETCO.sub.2),
an analysis of volumetric carbon dioxide (VCO.sub.2), a
determination that the expired volume is less than 50% of the
delivered volume, a determination that monitored PEEP is a negative
number for one second or less during the inspiratory effort, and an
analysis of a ratio of inspiratory to expiratory time (I:E
ratio).
[0103] Ventilator 202 may further include a smart prompt module
226. As may be appreciated, multiple ventilatory parameters may be
monitored and evaluated in order to detect an implication of double
triggering. In addition, when double triggering is implicated, many
clinicians may not be aware of adjustments to ventilatory
parameters that may reduce or eliminate double triggering. As such,
upon detection of double triggering, the smart prompt module 226
may be configured to notify the clinician that double triggering is
implicated and/or to provide recommendations to the clinician for
mitigating double triggering. For example, smart prompt module 226
may be configured to notify the clinician by displaying a smart
prompt on display monitor 204 and/or within a window of the GUI.
According to additional embodiments, the smart prompt may be
communicated to and/or displayed on a remote monitoring system
communicatively coupled to ventilatory system 200. Alternatively,
in an automated embodiment, the smart prompt module 226 may
communicate with a ventilator control system so that the
recommendation may be automatically implemented to mitigate double
triggering.
[0104] In order to accomplish the various aspects of the
notification and/or recommendation message display, the smart
prompt module 226 may communicate with various other components
and/or modules. For instance, smart prompt module 226 may be in
communication with data processing module 222, double triggering
detection module 224, or any other suitable module or component of
the ventilatory system 200. That is, smart prompt module 226 may
receive an indication that double triggering has been implicated by
any suitable means. In addition, smart prompt module 226 may
receive information regarding one or more parameters that
implicated the presence of double triggering and information
regarding the patient's ventilatory settings and treatment.
Further, according to some embodiments, the smart prompt module 226
may have access to a patient's diagnostic information (e.g.,
regarding whether the patient has ARDS, COPD, asthma, emphysema, or
any other disease, disorder, or condition).
[0105] Smart prompt module 226 may further comprise additional
modules for making notifications and/or recommendations to a
clinician regarding the presence of double triggering. For example,
according to embodiments, smart prompt module 226 may include a
notification module 228 and a recommendation module 230. For
instance, smart prompts may be provided according to a hierarchical
structure such that a notification message and/or a recommendation
message may be initially presented in summarized form and, upon
clinician selection, an additional detailed notification and/or
recommendation message may be displayed. According to alternative
embodiments, a notification message may be initially presented and,
upon clinician selection, a recommendation message may be
displayed. Alternatively or additionally, the notification message
may be simultaneously displayed with the recommendation message in
any suitable format or configuration.
[0106] Specifically, according to embodiments, the notification
message may alert the clinician as to the detection of a patient
condition, a change in patient condition, or an effectiveness of
ventilatory treatment. For example, the notification message may
alert the clinician that double triggering has been detected. The
notification message may further alert the clinician regarding the
particular ventilatory parameter(s) that implicated double
triggering (e.g., T.sub.E<210 ms, etc.)
[0107] Additionally, according to embodiments, the recommendation
message may provide various suggestions to the clinician for
addressing a detected condition. That is, if double triggering has
been detected, the recommendation message may suggest that the
clinician consider changing to a spontaneous breath type, such as
PA, PS, or VS etc. According to additional embodiments, the
recommendation message may be based on the particular ventilatory
parameter(s) that implicated double triggering. Additionally or
alternatively, the recommendation message may be based on current
ventilatory settings (e.g., breath type) such that suggestions are
directed to a particular patient's treatment. Additionally or
alternatively, the recommendation message may be based on a
diagnosis and/or other patient attributes. Further still, the
recommendation message may include a primary recommendation message
and a secondary recommendation message.
[0108] As described above, smart prompt module 226 may also be
configured with notification module 228 and recommendation module
230. The notification module 228 may be in communication with data
processing module 222, double triggering detection module 224, or
any other suitable module to receive an indication that double
triggering has been detected. Notification module 228 may be
responsible for generating a notification message via any suitable
means. For example, the notification message may be provided as a
tab, banner, dialog box, or other similar type of display. Further,
the notification messages may be provided along a border of the
graphical user interface, near an alarm display or bar, or in any
other suitable location. A shape and size of the notification
message may further be optimized for easy viewing with minimal
interference to other ventilatory displays. The notification
message may be further configured with a combination of icons and
text such that the clinician may readily identify the message as a
notification message.
[0109] The recommendation module 230 may be responsible for
generating one or more recommendation messages via any suitable
means. The one or more recommendation messages may provide
suggestions and information regarding addressing a detected
condition and may be accessible from the notification message. For
example, the one or more recommendation messages may identify the
parameters that implicated the detected condition, may provide
suggestions for adjusting one or more ventilatory parameters to
address the detected condition, may provide suggestions for
checking ventilatory equipment or patient position, or may provide
other helpful information. Specifically, the one or more
recommendation messages may provide suggestions and information
regarding double triggering.
[0110] According to embodiments, based on the particular parameters
that implicated double triggering, the recommendation module 230
may provide suggestions for addressing double triggering. That is,
if double triggering is implicated, the one or more recommendation
messages may include suggestions for the following: [0111]
increasing T.sub.I by changing the flow pattern, setting to
decelerating ramp; [0112] changing the flow pattern setting to
decelerating ramp; [0113] increasing set T.sub.I; [0114] decreasing
set E.sub.SENS; [0115] decreasing peak flow; [0116] increasing set
V.sub.T; [0117] changing modes or breath types; [0118] increasing
set V.sub.T while increasing peak flow rate setting to maintain
T.sub.I; [0119] increasing peak flow rate setting to maintain
T.sub.I; [0120] increasing set V.sub.T and changing the flow
pattern to square; [0121] changing flow pattern to square; and
[0122] etc.
[0123] Additionally or alternatively, the one or more
recommendation messages may be based on a patient's diagnosis or
other clinical data. According to some embodiments, if a patient
has been diagnosed with COPD, the ventilator may be configured with
adjusted thresholds. In further embodiments, if a patient has been
diagnosed with emphysema, the ventilator may be configured with
adjusted thresholds accordingly.
[0124] According to still other embodiments, the recommendation
message may include a primary message and a secondary message. That
is, a primary message may provide suggestions that are specifically
targeted to the detected condition based on the particular
parameters that implicated the condition. Alternatively, the
primary message may provide suggestions that may provide a higher
likelihood of mitigating the detected condition. The secondary
message may provide more general suggestions and/or information
that may aid the clinician in further addressing and/or mitigating
the detected condition. For example, the primary message may
provide a specific suggestion tor adjusting a particular parameter
to mitigate the detected condition (e.g., consider decreasing set
E.sub.SENS). Alternatively, the secondary message may provide
general suggestions for addressing the detected condition.
[0125] Additionally or alternatively, the one or more
recommendation messages may also be based on current ventilator
settings for the patient. For example, if double triggering was
implicated during a VC breath type, where the patient's current
ventilator settings included a set T.sub.I<IBW-predicted
T.sub.I, flow pattern set to square, and set V.sub.T.gtoreq.8
ml/kg, then the one or more recommendation messages may suggest
increasing the time for inspiration by changing the flow pattern
setting to a decelerating ramp or decreasing the peak flow rate.
Further in this example, a secondary recommendation message may
suggest changing the breath type to VC+, PC, or a spontaneous
breath type, such as PA, PS, or VS. Table 1 below lists various
example primary and secondary recommendations for volume-control
ventilation based on the listed current ventilator settings.
TABLE-US-00001 TABLE 1 VC ventilation recommendation messages based
on current ventilator settings. Ventilator Settings Primary
Recommendation Message Secondary Recommendation Message Set
(calculated) T.sub.I is < Consider increasing the time Consider
changing to VC+, IBW-predicted T.sub.I; for inspiration by changing
PC or a spontaneous breath Flow pattern is set to the flow pattern
setting to type such as PA, PS, VS. square; and decelerating ramp,
Set V.sub.T < 8 ml/kg. decreasing peak flow rate, or increasing
set V.sub.T. Set (calculated) T.sub.I is < Consider increasing
the time Consider changing to VC+, IBW-predicted T.sub.I; for
inspiration by decreasing PC or a spontaneous breath Flow pattern
is set to the peak flow rate setting. type such as PA, PS, or VS.
decelerating ramp; and V.sub.T .gtoreq. 8 ml/kg. Set (calculated)
T.sub.I is < Consider increasing the time Consider changing to
VC+, IBW-predicted T.sub.I; for inspiration by decreasing PC or a
spontaneous breath Flow pattern is set to the peak flow rate
setting or type such as PA, PS, VS. decelerating ramp; and
increasing set V.sub.T. V.sub.T < 8 ml/kg. Set (calculated)
T.sub.I is .gtoreq. Consider increasing set V.sub.T Consider
changing to VC+, IBW-predicted T.sub.I; and while increasing the
peak PC or a spontaneous breath Flow pattern is set to flow rate
setting to maintain type such as PA, PS, or VS. square. T.sub.I.
Set (calculated) T.sub.I is .gtoreq. Consider increasing set
V.sub.T Consider changing to VC+, IBW-predicted T.sub.I; and while
changing the flow PC or a spontaneous breath Flow pattern is set to
pattern setting to square type such as PA, PS, or VS. decelerating
ramp. and/or increasing the peak flow rate setting to maintain
T.sub.I.
[0126] In some embodiments, if double triggering is implicated
during a PC or VC+ breath type, the one or more recommendation
messages may suggest increasing a set T.sub.I.
[0127] According to further embodiments, if double triggering is
implicated during the PC or VC+ breath type, a secondary
recommendation message may suggest changing to a spontaneous breath
type, such as PA, PS, or VS breath type.
[0128] According to further embodiments, if double triggering is
implicated during a PS or VS breath type, the one or more
recommendation messages may suggest decreasing a set E.sub.sens. In
some embodiments, if double triggering is implicated during the PS
or VS breath type, a secondary recommendation message may suggest
changing to a spontaneous breath type, such as PA.
[0129] Smart prompt module 226 may also be configured such that
notification and/or recommendation messages may be displayed in a
partially transparent window or format. The transparency may allow
for notification and/or recommendation messages to be displayed
such that normal ventilator GUI and respiratory data may be
visualized behind the messages. This feature may be particularly
useful for displaying detailed messages. As described previously,
notification and/or recommendation messages may be displayed in
areas of the display screen that are either blank or that cause
minimal distraction from the respiratory data and other graphical,
representations provided by the GUI. However, upon selective
expansion of a message, respiratory data and graphs may be at least
partially obscured. As a result, translucent display may provide
the detailed message such that it is partially transparent. Thus,
graphical and other data may be visible behind the detailed alarm
message.
[0130] Additionally, notification and/or recommendation messages
may provide immediate access to the display and/or settings screens
associated with the detected condition. For example, an associated
parameter settings screen may be accessed from a notification
and/or a recommendation message via a hyperlink such that the
clinician may address the detected condition as necessary. An
associated parameter display screen may also be accessed such that
the clinician may view clinical data associated with the detected
condition in the form of charts, graphs, or otherwise. That is,
according to embodiments, the clinician may access the ventilatory
data that implicated the detected condition for verification
purposes. For example, when double triggering has been implicated,
depending on the particular ventilatory parameters that implicated
the double triggering, the clinician may be able to access
ventilatory settings for addressing double triggering (e.g., a
settings screen for adjusting V.sub.T, T.sub.I, etc.) and/or to
view associated ventilatory parameters that implicated double
triggering (e.g., a graphics screen displaying historical flow
waveforms, volume waveforms, and/or pressure waveforms that gave
rise to implications of double triggering).
[0131] According to embodiments, upon viewing the notification
and/or recommendation messages, upon addressing the detected
condition by adjusting one or more ventilatory settings or
otherwise, or upon manual selection, the notification and/or
recommendation messages may he cleared from the graphical user
interface. According to some embodiments, smart prompt module 226
clears the one or more messages from the graphical user interface
if the breath type is changed. In further embodiments, smart prompt
module 226 clears the one or more messages from the graphical user
interlace if a ventilator setting change was performed by the
operator and within a predetermined amount of time (e.g. 60 seconds
or 180 seconds) two patient-initiated mandatory breaths are greater
than the predetermined expiratory time threshold (e.g. .gtoreq.210
ms) and/or none of the patient-initiated mandatory breaths have an
expiratory time less than the predetermined expiratory time
threshold (e.g. <210 ms), in further embodiments, smart prompt
module 226 clears the one or more messages from the graphical user
interface, if within a predetermined amount of time (e.g. 60
seconds or 180 seconds) three patient-initiated mandatory breaths
are greater than the predetermined expiratory time threshold (e.g.,
.gtoreq.210 ms) and/or none of the patient-initiated mandatory
breaths have an expiratory time less than the predetermined
expiratory time threshold (e.g., <210 ms).
Double Triggering Detection during Ventilation of a Patient
[0132] FIG. 3 is a flow chart illustrating an embodiment of a
method 300 for detecting an implication of double triggering.
[0133] As should be appreciated, the particular steps and methods
described herein are not exclusive and, as will be understood by
those skilled in the art, the particular ordering of steps as
described herein is not intended to limit the method, e.g., steps
may be performed in differing order, additional steps may be
performed, and disclosed steps may be excluded without departing
from the spirit of the present methods.
[0134] The illustrated embodiment of the method 300 depicts a
method for detecting double triggering during ventilation of a
patient. Method 300 begins with an initiate ventilation operation
302. Initiate ventilation operation 302 may further include various
additional operations. For example, initiate ventilation operation
302 may include receiving one or more ventilatory settings
associated with ventilation of a patient (e.g., at receive settings
operation 304). For example, the ventilator may be configured to
provide ventilation to a patient. As such, the ventilatory settings
and/or input received may include a prescribed V.sub.T, set flow
(or peak flow), predicted or ideal body weight (PBW or IBW), etc.
According to some embodiments, a predicted T.sub.E may be
determined based on normal respiratory and compliance values or
value ranges based on the patient's PBW or IBW.
[0135] According to some embodiments, initiate ventilation
operation 302 may further include receiving diagnostic-information
regarding the patient (e.g., at receive diagnosis operation 306,
represented with dashed lines to identify the receive diagnosis
operation 306 as optional). For example, according to embodiments,
the clinician may indicate that the patient has been diagnosed with
ARDS, COPD, emphysema, asthma, etc. The ventilator may be further
configured to associate a patient diagnosis with various conditions
(e.g., increased resistance associated with COPD, increased
likelihood of alveolar collapse associated with ARDS, etc.).
[0136] At deliver ventilation operation 308, the ventilator
provides ventilation to a patient, as described above. That is,
according to embodiments, the ventilator provides ventilation based
on the set breath type. For example, during a VC breath type, the
ventilator provides ventilation based on a prescribed V.sub.T. In
this example, the ventilator may deliver gases to the patient at a
set flow at a set RR. When prescribed V.sub.T has been delivered,
the ventilator may initiate the expiratory phase.
[0137] While ventilation is being delivered, the ventilator may
conduct various data processing operations. For example, at data
processing operation 310, the ventilator may collect and/or derive
various ventilatory parameter data associated with ventilation of
the patient. For example, as described above, the ventilator may
collect data regarding expiratory time, V.sub.T, T.sub.I, etc.
parameters. Additionally, the ventilator may derive various
ventilatory parameter data based on the collected data, e.g.,
IBW-predicted T.sub.I, volume, respiratory resistance, respiratory
compliance, etc. As described previously, measurements for
respiratory resistance and/or compliance may be trended
continuously for a patient because ventilatory data may he obtained
without sedating the patient or otherwise. Additionally, the
ventilator may generate various graphical representations of the
collected and/or derived ventilatory parameter data, e.g., flow
waveforms, pressure waveforms, pressure-volume loops, flow-volume
loops, etc.
[0138] At analyze operation 312, the ventilator may evaluate
collected and/or derived data to determine whether a certain
patient condition exists. For example, according to embodiments,
the ventilator may evaluate the various collected and derived
parameter data, including expiratory time, delivered tidal volume,
etc., based on one or more predetermined thresholds. According to
embodiments, the ventilator may further evaluate the ventilatory
parameter data in light of the patient's specific parameter
settings, including set tidal volume, etc., and/or the patient's
diagnostic information. In some embodiments, the evaluation of the
various collected and derived parameter data includes a patient
circuit disconnection operation. The patient circuit disconnection
operation determines whether the patient circuit has become
disconnected from the patient and/or ventilator. The analyze
operation 312 determines that a patient circuit is disconnected by
any suitable means. In some embodiments, the analyze operation 312
determines that the patient circuit has become disconnected by
evaluating exhaled pressure and/or exhaled volume. In further
embodiments, analyze operation 312 determines if the patient
circuit is disconnected by determining if a disconnect alarm has
been executed. If the disconnect alarm has been executed, then
analyze operation 312 determines that the patient circuit is
disconnected. If the disconnect alarm has not been executed, then
analyze operation 312 determines that the patient circuit is
connected.
[0139] According to some embodiments, at detect double triggering
operation 314 the ventilator may determine whether double
triggering is implicated by evaluating expiratory time, exhaled
tidal volume, inspiratory time setting (T.sub.I), patient circuit
connection, etc., and compare the evaluated parameters to one or
more predetermined thresholds. In order to prevent unnecessary
alarms, notifications, and/or recommendations, thresholds and
conditions are utilized by the detect double triggering operation
314 to determine when double triggering has occurred with
sufficient frequency to warrant notification of the operator. For
example, in some embodiments, a double trigger that occurs in
isolation from any other double trigger will not be considered
enough to warrant an occurrence of double triggering by detect
double triggering operation 314.
[0140] In some embodiments, at detect double triggering operation
314 the ventilator may determine whether double triggering is
implicated based on a predetermined frequency. In further
embodiments, at detect double triggering operation 314 the
ventilator may determine whether double triggering is implicated
based on whether a double trigger occurred more than three times,
for more than 30% of the patient-initiated mandatory breaths, or
for more than 10% of the patient-initiated mandatory breaths within
a predetermined amount of time (e.g. 60 seconds or 180 seconds) at
analyze operation 312. For example, a double trigger is detected
when at least one of the following three predetermined thresholds
are exceeded: [0141] 1. expiratory time for a patient-initiated
mandatory breath is less than 240 ms; [0142] 2. exhaled tidal
volume associated with the expiratory period is less than 10% of
the delivered tidal volume of the prior inspiratory period; and
[0143] 3. a disconnect alarm is not detected.
[0144] In further embodiments, threshold number 1, listed above,
may be any suitable period. For example, in an alternative
embodiment the expiratory time threshold is an expiratory time of
less than 230 ms, 220 ms, 210 ms, 200 ms, or 190 ms depending upon
the type of ventilator, patient, breath type, ventilator
parameters, ventilator settings, and/or ventilator modes, etc. In
some embodiment, the predetermined amount of time starts at the
beginning of each patient-initiated breath. If double triggering is
implicated, the detect double triggering operation 314 may proceed
to issue smart prompt operation 316. If double triggering is not
implicated, the detect double triggering operation 314 may return
to analyze operation 312.
[0145] The three thresholds listed above are just one example list
of possible conditions that could be used to indicate double
triggering in the detect double triggering operation 314. Any
suitable list of condition for determining the occurrence of double
triggering may be utilized by the detect double triggering
operation 314. As may be appreciated, the ventilator may determine
whether double triggering is implicated at detect double triggering
operation 314 via any suitable means. Indeed, any of the above
described ventilatory parameters may be evaluated according to
various thresholds for detecting double triggering. Further, the
disclosure regarding specific ventilatory parameters as they may
implicate double triggering is not intended to be limiting. In
fact, any suitable ventilatory parameter may be monitored and
evaluated for detecting double triggering within the spirit of the
present disclosure. As such, if double triggering is implicated via
any suitable means, the detect double triggering operation 314 may
proceed to issue smart prompt operation 316. If double triggering
is not implicated, the detect double triggering operation 314 may
return to analyze operation 312.
[0146] At issue smart prompt operation 316, the ventilator may
alert the clinician via any suitable means that double triggering
has been implicated. For example, according to embodiments, the
ventilator may display a smart prompt including a notification
message and/or a recommendation message regarding the detection of
double triggering on the GUI. According to alternative embodiments,
the ventilator may communicate the smart prompt, including the
notification message and/or the recommendation message, to a remote
monitoring system communicatively coupled to the ventilator.
[0147] According to embodiments, the notification message may alert
the clinician that double triggering has been detected and,
optionally, may provide information regarding the ventilatory
parameter(s) that implicated double triggering. According to
additional embodiments, the recommendation message may provide one
or more suggestions for mitigating double triggering. According to
further embodiments, the one or more suggestions may be based on
the patient's particular ventilatory settings (e.g. breath type,
T.sub.I, V.sub.T, etc.) and/or diagnosis. According to some
embodiments, the clinician may access one or more parameter setting
and/or display screens from the smart prompt via a hyperlink or
otherwise for addressing doable triggering. According to additional
or alternative embodiments, a clinician may remotely access one or
more parameter and/or display screens from the smart prompt via a
hyperlink or otherwise for remotely addressing double
triggering.
[0148] Smart Prompt Generation regarding Double Triggering
Detection
[0149] FIG. 4 is a flow chart illustrating an embodiment of a
method 400 for issuing a smart prompt upon detecting an implication
of double triggering.
[0150] As should be appreciated, the particular steps and methods
described herein are not exclusive and, as will be understood by
those skilled in the art, the particular ordering of steps as
described herein is not intended to limit the method, e.g., steps
may be performed in differing order, additional steps may be
performed, and disclosed steps may be excluded without departing
from the spirit of the present methods.
[0151] The illustrated embodiment of the method 400 depicts a
method for issuing a smart prompt upon detecting double triggering
during ventilation of a patient. Method 400 begins with detect
operation 402, wherein the ventilator defects that double
triggering is implicated, as described above in method 300.
[0152] At identify ventilatory parameters operation 404, the
ventilator may identify one or more ventilatory parameters that
implicated double triggering. In order to prevent unnecessary
alarms, notifications, and/or recommendations, thresholds and
conditions are utilized by identify ventilatory parameters
operation 404 to determine when double triggering has occurred with
sufficient infrequency to warrant notification of the operator. For
example, in some embodiments, a double trigger that occurs in
isolation from any other double trigger will not be considered
enough to warrant an occurrence of double triggering by identify
ventilatory parameters operation 404.
[0153] For example, the ventilator may recognize that double
triggering was implicated based on whether a double trigger
occurred, more than three times for more than 30% of the
patient-initiated mandatory breaths, or for more than 10% of the
patient-initiated mandatory breaths within a predetermined amount
of time (e.g. 60 seconds or 180 seconds). For example, a double
trigger happens when at least one of three following predetermined
thresholds are exceeded: [0154] 1. expiratory time for a
patient-initiated mandatory breath is less than 240 ms; [0155] 2.
exhaled tidal volume associated with the expiratory period is less
than 10% of the delivered tidal volume of the prior inspiratory
period; and [0156] 3. a disconnect alarm is not detected.
[0157] In further embodiments, threshold number 1, listed above,
may refer to any suitable expiratory period. For example, in an
alternative embodiment the expiratory time threshold is an
expiratory time of less than 230 ms, 220 ms, 210 ms, 200 ms, or 190
ms depending upon the type of ventilator, patient, breath type,
ventilator parameters, ventilator setting, and/or ventilator modes,
etc. In some embodiment, the predetermined amount of time starts at
the beginning of each patient-initiated breath. The three
thresholds listed above are just one example list of possible
conditions that could be used to indicate double triggering in the
parameters operation 404. Any suitable list of conditions for
determining the occurrence of double triggering may be utilized by
the parameters operation 404. As may be appreciated, the ventilator
may use information regarding ventilatory parameters that
implicated double triggering in determining an appropriate
notification and/or recommendation message of the smart prompt.
[0158] At identify settings operation 406, the ventilator may
identify one or more current ventilatory settings associated with
the ventilatory treatment of the patient. For example, current
ventilatory settings may have been received upon initiating
ventilation for the patient and may have been determined by the
clinician or otherwise (e.g., breath type, oxygenation, PBW or IBW,
disease conditions, etc.). For instance, current ventilatory
settings associated with ventilation for a patient may include,
V.sub.T, T.sub.I, flow, E.sub.SENS, flow pattern, IBW-predicted
based on T.sub.I etc. In addition, a predicted T.sub.E may have
been determined based on normal respiratory resistance and
compliance values and the patient's PBW (or IBW). As may be
appreciated, the ventilator may use information regarding current
ventilatory settings in determining an appropriate notification
and/or recommendation message of the smart prompt.
[0159] At identify patient diagnosis operation 408, the ventilator
may optionally identify patient diagnosis information received from
a clinician (represented with dashed lines to identity the
operation as optional). For example, according to embodiments, the
clinician may indicate during ventilation initiation or otherwise
that the patient was diagnosed with COPD, ARDS, emphysema, asthma,
etc. As may be appreciated, the ventilator may use information
regarding a patient's diagnosis in determining an appropriate
notification and/or recommendation message of the smart prompt.
[0160] At determine operation 410, the ventilator may determine an
appropriate notification message. For example, the appropriate
notification message may alert the clinician that double triggering
has been implicated and, optionally, may provide information
regarding the ventilatory parameter(s) that implicated double
triggering. For example, the appropriate notification may alert the
clinician that double triggering was implicated because a double
trigger occurred in more than 10% of the patient-initiated
mandatory breaths, more than 30% of the patient-initiated mandatory
breaths, more than three instances of the patient-initiated
mandatory breaths, more than 8 instances of the patient-initiated
mandatory breaths, etc. within the predetermined amount of time. In
some embodiments, the predetermined amount of time is measured from
the beginning of each patient-initiated breath. For example, if
double triggering was detected because a double trigger was
detected in 3 or more instances of the patient-initiated mandatory
breaths within the last 60 seconds, the ventilator may offer one or
more notification messages that may include: "Double triggering has
occurred in more than 3 instances of the breaths in one minute." In
alternative embodiments, measured parameters such as inspiratory
time and volume may be utilized as the notification message.
[0161] At determine operation 412, the ventilator may determine an
appropriate primary recommendation message. The appropriate primary
recommendation message may provide one or more specific suggestions
for mitigating double triggering. According to some embodiments, in
determining the appropriate primary recommendation message, the
ventilator may take into consideration the one or more monitored
ventilatory parameters that implicated double triggering.
[0162] According to other embodiments, in determining an
appropriate primary recommendation message the ventilator may take
into consideration one or more of the patient's ventilatory
settings. For example, if the breath type is volume-control (VC)
and if T.sub.I is greater than an IBW-predicted T.sub.I, and the
flow pattern is set to decelerating ramp, the ventilator may offer
one or more recommendation messages that may include: "Consider
increasing set V.sub.T while changing flow pattern setting to
square"; "Consider increasing peak flow rate setting to maintain
T.sub.I." In another example, if the breath type is set to
pressure-control, then the ventilator may offer one or more
recommendation messages that may include: "Consider increasing the
set T.sub.I." Any of the primary recommendations as discussed above
for any breath type may be utilized by method 400.
[0163] According to further embodiments, in determining the
appropriate primary recommendation message the ventilator may take
into consideration the patient's diagnosis. For example, if a
patient has been diagnosed with COPD or ARDS, in determining an
appropriate primary recommendation message, the ventilator may
consider the patient's diagnosis.
[0164] At determine operation 414, the ventilator may determine an
appropriate secondary recommendation message. The secondary
recommendation message may provide one or more general suggestions
for mitigating double triggering. For example, the secondary
recommendation message may include: "Consider changing to VC+ or
PC; Consider changing to spontaneous breath type such as PA, PS, or
VS; Consider changing to a spontaneous breath type such as PA." The
secondary recommendation message may provide additional
recommendations for mitigating double triggering. In further
embodiments, the appropriate secondary recommendation message may
take into consideration the patient's current ventilatory settings.
That is, during a PS or a VS breath type, the ventilator may
suggest changing to a spontaneous breath type such as PA in the
secondary recommendation message.
[0165] At issue smart prompt operation 416, the ventilator may
alert the clinician via any suitable means that double triggering
has been implicated. For example, according to embodiments, a smart
prompt may include an appropriate notification message and an
appropriate recommendation message regarding the presence of double
triggering. Additionally or alternatively, the smart prompt may
include an appropriate notification message, an appropriate primary
recommendation message, and an appropriate secondary recommendation
message. The smart prompt may be displayed via any suitable means,
e.g., on the ventilator GUI and/or at a remote monitoring station,
such that the clinician is alerted as to the potential presence of
double triggering and offered additional information and/or
recommendations for mitigating the double triggering, as described
herein.
[0166] In some embodiments, a ventilatory system for issuing a
smart prompt when double triggering is implicated during
ventilation of a patient is disclosed. The ventilatory system
includes: means for collecting data associated with ventilatory
parameters; means for processing the collected ventilatory
parameter data, wherein the means for processing the collected
ventilatory parameter data includes means for deriving ventilatory
parameter data from the collected ventilatory parameter data; means
for analyzing the processed ventilatory parameter data, wherein the
means for analyzing the processed ventilatory parameter data
includes: means for receiving at least one predetermined threshold
associated with the processed ventilatory parameter data; and means
for detecting whether the processed ventilatory parameter data
breaches the received at least one predetermined threshold at a
predetermined frequency; means for determining that double
triggering is implicated for a patient upon detecting that the
processed ventilatory data breaches the received at least one
predetermined threshold at the predetermined frequency; and means
for issuing a smart prompt when the double triggering is
implicated. In further embodiments, the means for the medical
ventilator are illustrated in FIGS. 1 and 2 and are described in
the above descriptions of FIGS. 1 and 2. However, the means
described above for FIGS. 1 and 2 and illustrated in FIGS. 1 and 2
are but one example only and are not meant to be limiting.
Ventilator GUI Display of Initial Smart Prompt
[0167] FIG. 5 is an illustration of an embodiment of a graphical
user interface 500 displaying a smart prompt having a notification
message 512.
[0168] Graphical user interface 500 may display various monitored
and/or derived data to the clinician during ventilation of a
patient. In addition, graphical user interface 500 may display
various messages to the clinician (e.g., alarm messages, etc.).
Specifically, graphical user interlace 500 may display a smart
prompt as described herein.
[0169] According to embodiments, the ventilator may monitor and
evaluate various ventilatory parameters based on one or more
predetermined thresholds to detect double triggering. As
illustrated, a flow waveform may be generated and displayed by the
ventilator on graphical user interlace 500. As further illustrated,
the flow waveform may be displayed such that inspiratory flow 502
is represented in a different color (e.g., green) than explanatory
flow 504 (e.g., yellow). Additionally, as illustrated, a double
trigger 506 occurs when the ventilator delivers two or more breaths
separated by a very short expiratory time, with at least one breath
being triggered by the patient. Double triggering results when
there is a mismatch between the ventilation setting for inspiratory
time and the patient's neurological inspiratory time. Double
triggering may also result when there is a mismatch between the
flow and set inspiratory time and the patient's desired flow and
neurological inspiratory time. In order to prevent unnecessary
alarms, notifications, and/or recommendations, thresholds and
conditions are utilized to determine when double triggering has
occurred with sufficient frequency to warrant notification of the
operator.
[0170] That is, double triggering may be detected if a double
trigger occurred more than three times, for more than 30% of the
patient-initiated mandatory breaths, or for more than 10% of the
patient-initiated mandatory breaths within a predetermined amount
of time (e.g. 60 seconds or 180 seconds). For example, a double
trigger happens when at least one of three following predetermined
thresholds are breached: [0171] 1. expiratory time for a
patient-initiated mandatory breath is less than 240 ms; [0172] 2.
exhaled tidal volume associated with the expiratory period is less
than 10% of the delivered tidal volume of the prior inspiratory
period; and [0173] 3. a disconnect alarm is not detected.
[0174] In further embodiments, threshold number 1, listed above,
may be any suitable period. For example, in an alternative
embodiment the expiratory time threshold is an expiratory time of
less than 230 ms, 220 ms, 210 ms, 200 ms, or 190 ms depending upon
the type of ventilator, patient, breath type, ventilator
parameters, ventilator setting, and/or ventilator modes, etc. In
some embodiment, the predetermined amount of time starts at the
beginning of each patient-initiated breath. The three thresholds
listed above are just one example list of possible conditions that
could be used to indicate doable triggering. Any suitable list of
conditions for determining the occurrence of double triggering may
be utilized.
[0175] Upon a determination that double triggering is implicated,
the graphical user interlace 500 may display a smart prompt, e.g.,
smart prompt 510.
[0176] According to embodiments, smart prompt 510 may be displayed
in any suitable location such that a clinician may be alerted
regarding a detected patient condition, but while allowing other
ventilatory displays and data to be visualized substantially
simultaneously. As illustrated, smart prompt 510 is presented as a
bar or banner across an upper region of the graphical user
interlace 500. However, as previously noted, smart prompt 510 may
be displayed as a tab, icon, button, banner, bar, or any other
suitable shape or form. Further, smart prompt 510 may be displayed
in any suitable location within the graphical user interface 500.
For example, smart prompt 510 may be located along any border
region of the graphical user interface 500 (e.g., top, bottom, or
side borders) (not shown), across an upper region (shown), or in
any other suitable location. Further, as described herein, smart
prompt 510 may he partially transparent (not shown) such that
ventilatory displays and data may be at feast partially visible
behind smart prompt 510.
[0177] Specifically, smart prompt 510 may alert the clinician that
double triggering has been defected, for example by notification
message 512. As described herein, notification message 512 may
alert the clinician that double triggering is implicated via any
suitable means, e.g., "Double Triggering Alert" (shown), "Double
Triggering Detected" (not shown), or "Double Triggering Implicated"
(not shown). Smart prompt 510 may further include information
regarding ventilatory parameters that implicated double triggering.
For example, if double triggering was detected based on two set
mechanical breaths being delivered for one patient-initiated
mandatory breath three times in one minute, this information may be
displayed by the notification message 512 (e.g., "Double Triggering
has occurred in more than 10% of the breaths in a minute," shown).
According to the illustrated embodiment, parameter information 514
is provided along with the notification message 312 in a banner.
According to alternative embodiments, in addition to the
notification message 512 and the parameter information 514, one or
more recommendation messages may be provided in an initial smart
prompt banner (not shown). According to other embodiments, rather
than providing information regarding ventilatory parameters that
implicated double triggering in the initial smart prompt, this
information may be provided within an expanded portion (not shown)
of smart prompt 510.
[0178] According to embodiments, smart prompt 510 may be expanded
to provide additional information and/or recommendations to the
clinician regarding a detected patient condition. For example, an
expand icon 516 may be provided within a suitable area of the smart
prompt 510. According to embodiments, upon selection of the expand
icon 516 via any suitable means, the clinician may optionally
expand the smart prompt 510 to acquire additional information
and/or recommendations for mitigating the detected patient
condition. According to further embodiments, smart prompt 510 may
include links (not shown) to additional settings and/or display
screens of the graphical user interface 500 such that the clinician
may easily and quickly mitigate and/or verify the detected
condition.
[0179] As may be appreciated, the disclosed data, graphics, and
smart prompt illustrated in graphical user interface 500 may be
arranged in any suitable order or configuration such that
information and alerts may be communicated to the clinician in an
efficient and orderly manner. The disclosed data, graphics, and
smart prompt are not to be understood as an exclusive array, as any
number of similar suitable elements may be displayed for the
clinician within the spirit of the present disclosure. Further, the
disclosed data, graphics, and smart prompt are not to be understood
as a necessary array, as any number of the disclosed elements may
be appropriately replaced by other suitable elements without
departing from the spirit of the present disclosure. The
illustrated embodiment of the graphical user interface 500 is
provided as an example only, including potentially useful
information and alerts that may be provided to the clinician to
facilitate communication of detected double triggering in an
orderly and informative way, as described herein.
Ventilator GUI Display of Expanded Smart Prompt
[0180] FIG. 6 is an illustration of an embodiment of a graphical
user interlace 600 displaying an expanded smart prompt 606 having a
notification message and one or more recommendation messages
608.
[0181] Graphical user interface 600 may display various monitored
and/or derived data to the clinician during ventilation of a
patient. In addition, graphical user interface 600 may display an
expanded smart prompt 606 including one or more recommendation
messages 608 as described herein.
[0182] According to embodiments, as described above, an expand icon
604 may be provided within a suitable area of smart prompt 602.
Upon selection of the expand icon 604, the clinician may optionally
expand smart prompt 602 to acquire additional information and/or
recommendations for mitigating the detected patient condition. For
example, expanded smart prompt 606 may be provided upon selection
of expand icon 604. As described above for smart prompt 510,
expanded smart prompt 606 may be displayed as a tab, icon, button,
banner, bar, or any other suitable shape or form. Further, expanded
smart prompt 606 may be displayed in any suitable location within
the graphical user interface 600. For example, expanded smart
prompt 606 may be displayed below (shown) smart prompt 602, to a
side (not shown) of smart prompt 602, or otherwise logically
associated with smart prompt 602. According to other embodiments,
an initial smart prompt may be hidden (not shown) upon displaying
expanded smart prompt 606. Expanded small prompt 606 may also be
partially transparent (not shown) such that ventilatory displays
and data may be at least partially visible behind expanded smart
prompt 606.
[0183] According to embodiments, expanded smart prompt 606 may
comprise additional information (not shown) and/or one or more
recommendation messages 608 regarding detected double triggering.
For example, the one or more recommendation messages 608 may
include a primary recommendation message and a secondary
recommendation message. The primary recommendation message may
provide one or more specific suggestions for mitigating double
triggering. For example, if double triggering was implicated during
volume-control ventilation and if T.sub.I is greater than a
IBW-predicted T.sub.I and the flow pattern is set to decelerating
ramp, then the ventilator may offer one or more primary
recommendation messages 608 that may include: "Consider increasing
set V.sub.T while changing flow pattern setting to square; Consider
changing to VC+ or PC; Consider changing to spontaneous breath type
such as PA, PS, or VS; Consider increasing peak flow rate setting
to maintain T.sub.I." The secondary recommendation message may
provide one or more general suggestions for mitigating doable
triggering. For example, the secondary recommendation message may
include: "Consider changing to VC+ or PC; Consider changing to
spontaneous breath type such as PA, PS, or VS; Consider changing to
a spontaneous breath type such as PA."
[0184] According to embodiments, expanded smart prompt 606 may also
include one or more hyperlinks 610, which may provide immediate
access to the display and/or settings screens associated with
detected double triggering. For example, associated parameter
settings screens may be accessed from expanded smart prompt 606 via
hyperlinks 610 such that the clinician may address detected double
triggering by adjusting one or more parameter settings as
necessary. Alternatively, associated parameter display screens may
be accessed such that the clinician may view clinical data
associated with double triggering in the form of charts, graphs, or
otherwise. That is, according to embodiments, the clinician may
access the ventilatory data that implicated double triggering for
verification purposes. For example, when double triggering has been
implicated, depending on the particular ventilatory parameters that
implicated double triggering, the clinician may be able to access
associated parameter settings screens for addressing double
triggering (e.g., settings screens for adjusting V.sub.T, T.sub.I,
breath type, etc). Additionally or alternatively, the clinician may
be able to access and/or view display screens associated with the
ventilatory parameters that implicated double triggering (e.g., a
graphics screen displaying historical flow waveforms, volume
waveforms, and/or pressure waveforms that gave rise to implications
of double triggering).
[0185] As may be appreciated, the disclosed smart prompt and
recommendation messages 608 illustrated in graphical user interface
600 may be arranged in any suitable order or configuration such
that information and alerts may be communicated to the clinician in
an efficient and orderly manner. Indeed the illustrated embodiment
of the graphical user interface 600 is provided as an example only,
including potentially useful information and recommendations that
may be provided to the clinician to facilitate communication of
suggestions for mitigating detected double trigging in an orderly
and informative way, as described herein.
[0186] Unless otherwise indicated, all numbers expressing
measurements, dimensions, and so forth used in the specification
and claims are to he understood as being modified in all instances
by the term "about." Accordingly, unless indicated to the contrary,
the numerical parameters set forth in the following specification
and attached claims are approximations that may vary depending upon
the desired properties sought to be obtained by the present
disclosure. Further, unless otherwise stated, the term "about"
shall expressly include "exactly," consistent with the discussions
regarding ranges and numerical data. Concentrations, amounts, and
other numerical data may be expressed or presented herein in a
range format. It is to be understood that such a range format is
used merely for convenience and brevity and thus should be
interpreted flexibly to include not only the numerical values
explicitly recited as the limits of the range, but also to include
all the individual numerical values or sub-ranges encompassed
within that range as if each numerical value and sub-range is
explicitly recited. As an illustration, a numerical range of "about
4 percent to about 7 percent" should be interpreted to include not
only the explicitly recited values of about 4 percent to about 7
percent, but also include individual values and sub-ranges within
the indicated range. Thus, included in this numerical range are
individual values such as 4.5, 5.25 and 6 and subranges such as
from 4-5, from 5-7, and from 5.5-6.5, etc. This same principle
applies to ranges reciting only one numerical value. Furthermore,
such an interpretation should apply regardless of the breadth of
the range or the characteristics being described.
[0187] It will be clear that the systems and methods described
herein are well adapted to attain the ends and advantages mentioned
as well as those inherent therein. Those skilled in the art will
recognize that the methods and systems within this specification
may be implemented in many manners and as such is not to be limited
by the foregoing exemplified embodiments and examples. In other
words, functional elements being performed by a single or multiple
components, in various combinations of hardware and software, and
individual functions can be distributed among software applications
at either the client or server level. In this regard, any number of
the features of the different embodiments described herein may be
combined into one single embodiment and alternative embodiments
having fewer than or more than all of the features herein described
are possible.
[0188] While various embodiments have been described for purposes
of this disclosure, various changes and modifications may be made
which are well within the scope of the present disclosure. Numerous
other changes may be made which will readily suggest themselves to
those skilled in the art and which are encompassed in the spirit of
the disclosure and as defined in the appended claims.
* * * * *