U.S. patent application number 10/489159 was filed with the patent office on 2004-12-09 for breathing assistance apparatus.
Invention is credited to Leckie, Martin, Olsen, Gregory James, Prime, Neil.
Application Number | 20040244804 10/489159 |
Document ID | / |
Family ID | 19928743 |
Filed Date | 2004-12-09 |
United States Patent
Application |
20040244804 |
Kind Code |
A1 |
Olsen, Gregory James ; et
al. |
December 9, 2004 |
Breathing assistance apparatus
Abstract
A nasal cannula (100) for delivering respiratory gases to a
neonatal infant comprising a manifold including a chamber (10), a
gases inlet (16) to the chamber and a gases outlet (12), a low
resistance path for gases through the chamber from its inlet to its
outlet and a pair of nasal prongs (116, 118) in fluid communication
with the chamber with each prong substantial equidistant the inlet,
and directly in the low resistance path to eliminate deadspace.
Inventors: |
Olsen, Gregory James;
(Auckland, NZ) ; Leckie, Martin; (Auckland,
NZ) ; Prime, Neil; (Auckland, NZ) |
Correspondence
Address: |
Trexler Bushnell Giangiorgi
Blackstone & Marr
105 West Adams Street
Chicago
IL
60603
US
|
Family ID: |
19928743 |
Appl. No.: |
10/489159 |
Filed: |
August 3, 2004 |
PCT Filed: |
September 13, 2002 |
PCT NO: |
PCT/NZ02/00180 |
Current U.S.
Class: |
128/207.18 ;
128/200.26; 128/204.12; 128/204.18; 128/206.27; 128/207.13 |
Current CPC
Class: |
A61M 16/161 20140204;
A61M 16/208 20130101; A61M 16/0666 20130101; A61M 2205/3348
20130101; A61M 16/0633 20140204; A61M 16/0069 20140204; A61M
16/1095 20140204; A61M 16/0683 20130101; A61M 2240/00 20130101;
A61M 16/0066 20130101; A61M 16/0841 20140204; A61M 16/06 20130101;
A61M 16/16 20130101 |
Class at
Publication: |
128/207.18 ;
128/200.26; 128/207.13; 128/204.12; 128/204.18; 128/206.27 |
International
Class: |
A61M 016/00 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 13, 2001 |
NZ |
514184 |
Claims
1. A nasal cannula for delivering respiratory gases to a neonatal
infant comprising: a manifold including a chamber, a gases inlet
configured to engage an inspiratory conduit, a gases outlet
configured to engage an expiratory conduit and a low resistance
path for said gases through said chamber from said inlet to said
outlet a pair of nasal prongs in fluid communication with said
chamber substantial equidistant said inlet, said prongs juxtaposed
directly in said path.
2. A nasal cannula for delivering respiratory gases to a neonatal
infant as claimed in claim 1 wherein said cannula includes
securement means to hold said prongs in place in the nares of said
neonate.
3. A nasal cannula for delivering respiratory gases to a neonatal
infant as claimed in claim 2 wherein said securement means
including a strap adapted to pass around the back of the neck of
said neonate and engage with said cannula and thereby hold said
prongs in place in the nares of said neonate.
4. A nasal cannula for delivering respiratory gases to a neonatal
infant as claimed in claim 3 wherein said strap includes a low
resistance portion, said low resistance portion adapted to engage
with said cannula in a sliding fashion to allow said strap
substantial lateral (egonon axial) movement relative to said
cannula.
5. A nasal cannula for delivering respiratory gases to a neonatal
infant as claimed in claim 4 wherein said low resistance portion
comprises a thin plastic strand or strip.
6. A nasal cannula for delivering respiratory gases to a neonatal
infant as claimed in claim 5 wherein the remainder of said strap
includes an adjustable attachment to said low resistance portion to
in use adjust the tension of said strap.
7. A nasal cannula for delivering respiratory gases to a neonatal
infant as claimed in anyone of claims 2 to 6 wherein said
securement means including an infant bonnet comprising head cover
means adapted to at least partially cover the head of an infant and
including at least a cuff of elastic property to securely locate
said cover means on said infant head, and medical tube securing
means connected with said cover means on the outer surface thereof,
said medical tubes adapted to in use connect to said cannula, said
securing means operable to hold medical tubes passing over said
cover means against at least lateral (egonon axial) movement.
8. A nasal cannula for delivering respiratory gases to a neonatal
infant as claimed in claim 7 wherein said head cover means is
formed of a knit fabric in a tubular configuration and open at both
ends, said securing means is connected with said outer surface
adjacent one said open end and end closing means are connected with
said outer surface adjacent the other said open end, said end
closing means being operable to hold the said knit fabric of its
respective said end in a closed, bunched together, condition.
9. A nasal cannula for delivering respiratory gases to a neonatal
infant as claimed in claim 8 wherein either or both of said tube
securing means and said end closing means are or include a lace or
tie stitched to said head cover means.
10. A nasal cannula for delivering respiratory gases to a neonatal
infant as claimed in claim 9 wherein said lace or tieing is secured
at its centre to said head cover means to provide two arms, said
arms passing through a tightening toggle slidable on said arms.
11. A nasal cannula for delivering respiratory gases to a neonatal
infant as claimed in claim 10 wherein said tightening toggle is
operable between at least two conditions, being biased to a pinch
off condition in which said arms of said lace or tie are clamped
within their passage through said toggle and manipulable to a free
configuration in which said toggle may slide a long said arms of
said lace or tie.
12. A system for delivering respiratory gases in a neonatal infant
comprising a source of pressurised gases, an inhalatory conduit in
fluid communication with said source of gases and adapted to convey
gases, a nasal cannula in fluid communication with said inhalatory
conduit and adapted to deliver gases to the nasal passages of said
infant, an exhalatory conduit in fluid communication with said
delivery means and adapted to convey gases from said delivery
means, and a pressure regulating device disposed within or in fluid
communication with said exhalatory gases transport means and
adapted to achieve a predetermined mean pressure of gases delivered
to the nasal passages of said infant by regulating the flow of
gases through said pressure regulating device.
13. A system as claimed in claim 12 wherein pressure regulating
device comprising: a container adapted to house a body of liquid,
terminal conduit means including proximate and distal ends, said
proximate end adapted for connection to said exhalatory conduit,
and said distal end adapted for submergence in said body of liquid,
such that in use the mean pressure of gases delivered to the nasal
passages of said infant is determined by the level to which said
distal end is submerged in said body of liquid.
14. A system in as claimed in claim 13 wherein said nasal cannula
is constructed according to any one of claims 1 to 11.
Description
FIELD OF INVENTION
[0001] This invention relates to Nasal Cannulae particularly though
not solely to nasal cannulae for delivering Continuous Positive
Airway Pressure (CPAP) to neonates.
BACKGROUND
[0002] Certain individuals require a respiratory supplement such as
air, oxygen, or other gases. Such gases are freely supplied and/or
supplied at controlled pressures. Such gases are also supplied
through the patient's mouth and/or through the patient's nose.
Nasal supply systems provide an advantage in that they are
generally more convenient and less intrusive than mouth based or
mouth covering devices. Despite their convenience, nasal based
devices are deemed uncomfortable in light of securement straps
placed across the face and/or around the head and used to secure
the device to an individuals breathing cavity. Moreover,
conventional cannulas do not provide a proper seal around the nares
to inhibit apnoea and to provide a high flow system to stimulate
the patient's breathing. Hence, even with such securement straps,
these nasal devices often dislodge from the breathing cavity. This
is of particular concern with children, infants, or the elderly who
do not understand the importance of keeping the nasal breathing
device in place, whether it be a nasal CPAP or nasal cannula.
[0003] It is known to be beneficial and therapeutic to supply an
individual with a sufficient amount of respiratory airway pressure
in order to maintain a minimum level of air volume in the lungs. If
the air volume falls below this minimum level, then the lungs may
collapse, which can be extremely dangerous or even deadly to the
individual. Moreover, the back pressure can increase oxygen levels
in the lungs and decrease carbon dioxide levels. This will also
improve PH by removal of carbon dioxide, which is an acid, from the
blood. Hence, the application of such sufficient pressure, called
continuous positive airway pressure (CPAP), has been found to be
advantageous in maintaining a minimum air volume or lung pressure
when an individual is spontaneously breathing. CPAP can be supplied
through nasal attachment devices such as a nasal cannulae, or
through mouth based or endotracheal devices.
[0004] A number of CPAP devices are known including endotracheal
tubes, head chambers, face chambers, face masks, nasal prongs, and
nasal cannula. While each type of device has advantages and
disadvantages, the nasal cannula provides a comfortable alternative
for providing CPAP and/or airflow assistance. Prior art nasal
cannulae have been disclosed in many forms with various methods of
securing the device to the nasal passageway. One such cannula
assembly is disclosed in U.S. Pat. No. 3,513,844 which uses an
adjustable strap that encircles an individual's head. A similar
device is disclosed in U.S. Pat. No. 4,106,505 wherein the supply
tubes to the cannula are hooked over an individual's ears and
around the head. Even more cumbersome, U.S. Pat. No. 5,477,852
discloses a device with a headband for holding and positioning the
nasal inserts and associated supply tubes. Yet another system in
U.S. Pat. No. 5,271,391 discloses a cannula which is secured by
applying strips of pressure sensitive adhesive tape to the supply
tubes leading from each side of the cannula, thereby attaching the
supply tubes to the cheeks of an individual with the cannula
positioned in between.
[0005] "Bonnet" type devices are also used to hold the CPAP nasal
cannulae in place. However, this method generally puts pressure on
an individual's nose and upper lip thereby causing pressure
necrosis in the centre of the nose. A particularly sensitive
individual is a young child, infant or baby. The bonnet also fails
to adequately keep the nasal prongs in position, particularly with
infants who move or roll around in their crib. In a hospital or
care facility setting, it is not uncommon for an attendant to
discover that the CPAP device has been disconnected from a
patient's nose, which can lead to apnoea, desaturations,
bradycardia, or hypoxia which is dangerously low oxygen levels in
the blood. In practice, the tubing for these bonnet type CPAP's is
draped around both sides of the patient's cheek which means that
the most comfortable lying down position is on the patient's back.
Pressure on the patient's cheeks caused by the securement device
can make other positions uncomfortable.
[0006] Other prior art anchoring systems include adhesive devices
which attach directly to the nose. U.S. Pat. No. 4,823,789
discloses a nose tube anchoring strip which has an adhesive coated
sheet shaped to fit over an individual's nose and an appendage for
holding a nasal-gastric tube. A similar system is found in U.S.
Pat. No. 5,156,641 which has an anchoring cord adhesively attached
to an individual's nose at one end and attached to hold a
naso-gastric catheter at the other end. U.S. Pat. No. 5,513,635
provides a securement device with a body engagement portion which
adheres across the nose of an individual with cannula engaging
portions extending down therefrom. Similarly, U.S. Pat. No.
5,682,881 discloses the use of an adhesive foam pad secured to the
upper lip for positioning of the cannula.
[0007] In U.S. Pat. No. 3,643,660 a unified nasal cannula comprises
a hollow tubular body having an upper flat or plane surface and a
pair of spaced and curved elongated tubular extensions, having
exterior orifices for directing a gas flow which extensions project
upwardly at an angle from the surface. Referring to FIGS. 2 and 3
we see that because the inlet 400 is from one side the prongs
402,404 may see slightly different pressures. There is also the
potential for downstream prong 404 to rebreathe the expired
CO.sub.2 from upstream prong 402.
[0008] In U.S. Pat. No. 5,975,077 a cannula is disclosed including
an airway injecting gas in fluid communication with nostrils of a
patient and aerodynamically designed passageways for both the
ambient air and the injected gas to optimize the fluid flow
characteristics during inhalation and exhalation of the
patient.
[0009] In U.S. Pat. No. 4,774,946 a cannula is described attached
to an elongated flexible tube. The nasal prongs include bulbous
portions that seat and seal the nasal tubes in the nares.
[0010] In U.S. Pat. No. 5,193,532 a device is disclosed for
generating by ejector action a continuous positive airway pressure
(CPAP), comprising a breathing-channel which at one end opens into
the atmosphere and at another end is adapted to be provided with an
attachment device to the nose and/or mouth of the patient as seen
in FIG. 1. The inlet is situated between a channel open to the
atmosphere and open to the prongs in such a manner that the stream
of fresh gas is directed mainly co-axially into the channel,
producing an ejector action.
[0011] However, while these prior art systems do provide nasal CPAP
they suffer from a number of disadvantages including:
insufficiently securement to the patients head, potential for
unbalanced pressure in each prong, and potential for rebreathing of
expired CO.sub.2.
SUMMARY OF THE INVENTION
[0012] It is an object of the present invention to provide a nasal
cannula which goes someway to overcoming the above mentioned
disadvantages or which will at least give the public a useful
choice.
[0013] Accordingly in a first aspect the present invention maybe
broadly said to consist in nasal cannula for delivering respiratory
gases to a neonatal infant comprising:
[0014] a manifold including a chamber, a gases inlet configured to
engage an inspiratory conduit, a gases outlet configured to engage
an expiratory conduit and a low resistance path for said gases
through said chamber from said inlet to said outlet
[0015] a pair of nasal prongs in fluid communication with said
chamber substantial equidistant said inlet, said prongs juxtaposed
directly in said path.
[0016] Preferably said cannula includes securement means to hold
said prongs in place in the nares of said neonate.
[0017] Preferably said securement means including a strap adapted
to pass around the back of the neck of said neonate and engage with
said cannula and thereby hold said prongs in place in the nares of
said neonate.
[0018] Preferably said strap includes a low resistance portion,
said low resistance portion adapted to engage with said cannula in
a sliding fashion to allow said strap substantial lateral (iguanian
axial) movement relative to said cannula.
[0019] Preferably said low resistance portion comprises a thin
plastic strand or strip.
[0020] Preferably the remainder of said strap includes an
adjustable attachment to said low resistance portion to in use
adjust the tension of said strap.
[0021] Preferably said securement means including an infant bonnet
comprising head cover means adapted to at least partially cover the
head of an infant and including at least a cuff of elastic property
to securely locate said cover means on said infant head, and
medical tube securing means connected with said cover means on the
outer surface thereof, said medical tubes adapted to in use connect
to said cannula, said securing means operable to hold medical tubes
passing over said cover means against at least lateral (iguanian
axial) movement.
[0022] Preferably said head cover means is formed of a knit fabric
in a tubular configuration and open at both ends, said securing
means is connected with said outer surface adjacent one said open
end and end closing means are connected with said outer surface
adjacent the other said open end, said end closing means being
operable to hold the said knit fabric of its respective said end in
a closed, bunched together, condition.
[0023] Preferably either or both of said tube securing means and
said end closing means are or include a lace or tie stitched to
said head cover means.
[0024] Preferably said lace or tieing is secured at its centre to
said head cover means to provide two arms, said arms passing
through a tightening toggle slidable on said arms.
[0025] Preferably said tightening toggle is operable between at
least two conditions, being biased to a pinch off condition in
which said arms of said lace or tie are clamped within their
passage through said toggle and manipulable to a free configuration
in which said toggle may slide a long said arms of said lace or
tie.
[0026] In a second aspect the present invention may be broadly said
to consist in a system for delivering respiratory gases in a
neonatal infant comprising
[0027] a source of pressurised gases,
[0028] an inhalatory conduit in fluid communication with said
source of gases and adapted to convey gases,
[0029] a nasal cannula in fluid communication with said inhalatory
conduit and adapted to deliver gases to the nasal passages of said
infant,
[0030] an exhalatory conduit in fluid communication with said
delivery means and adapted to convey gases from said delivery
means, and
[0031] a pressure regulating device disposed within or in fluid
communication with said exhalatory gases transport means and
adapted to achieve a predetermined mean pressure of gases delivered
to the nasal passages of said infant by regulating the flow of
gases through said pressure regulating device.
[0032] Preferably pressure regulating device comprising:
[0033] a container adapted to house a body of liquid,
[0034] terminal conduit means including proximate and distal ends,
said proximate end adapted for connection to said exhalatory
conduit, and said distal end adapted for submergence in said body
of liquid,
[0035] such that in use the mean pressure of gases delivered to the
nasal passages of said infant is determined by the level to which
said distal end is submerged in said body of liquid.
[0036] To those skilled in the art to which the invention relates,
many changes in construction and widely differing embodiments and
applications of the invention will suggest themselves without
departing from the scope of the invention as defined in the
appended claims. The disclosures and the descriptions herein are
purely illustrative and are not intended to be in any sense
limiting.
[0037] The invention consists in the forgoing and also envisages
constructions of which the following gives examples.
BRIEF DESCRIPTION OF THE DRAWINGS
[0038] One preferred form of the present invention will now be
described with reference to the accompanying drawings in which:
[0039] FIG. 1 is a side view of a prior art cannula on an
infant,
[0040] FIG. 2 is a perspective view of a prior art cannula on an
infant,
[0041] FIG. 3 is a cross section of a prior art cannula,
[0042] FIG. 4 is a closeup perspective view from above of the
present invention,
[0043] FIG. 5 is a section view of the present invention,
[0044] FIG. 6 is a closeup perspective view of the present
invention,
[0045] FIG. 7 is a side view of the present invention,
[0046] FIG. 8 is a closeup view of the present invention from
below,
[0047] FIG. 9 is a closeup view of the present invention from
above,
[0048] FIG. 10 is an illustration of the present invention is use
on an neonate,
[0049] FIG. 11 is a block diagram of the CPAP system,
[0050] FIG. 12 is a side view of the bonnet, and
[0051] FIG. 13 is an illustration of the bonnet is use on an
neonate
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0052] Referring now to FIG. 11 in which a typical application is
depicted. A humidified Continuous Positive Airway Pressure (CPAP)
system is shown in which a patient 19 is receiving humidified and
pressurised gases through a nasal cannula 28 connected to a
inhalatory conduit 21. It should be understood that the present
invention, however, is not limited to the delivery of CPAP gases
but is also applicable to other types of gases delivery systems.
Inhalatory conduit 21 is connected to the outlet 12 of a
humidification chamber 10 which contains a volume of water 15.
Inspiratory conduit 21 may contain heating means or heater wires 20
which heat the walls of the conduit to ensure a constant humidity
profile along the conduit and therefore reduce condensation of
humidified gases within the conduit. As the volume of water 15
within humidification chamber 10 is heated, water vapour begins to
fill the volume of the chamber above the water's surface and is
passed out of the humidification chamber 10 outlet 12 with the flow
of gases (for example air) provided from a gases supply means or
blower 18 which enters the chamber 10 through inlet 16.
[0053] The humidified gases pass through the inhalatory conduit 21
to the cannula 100 connected to the patient's 19 nose through
prongs 116,118. The expired gases pass through the prongs 116,118
to the output manifold 130. The excess gases then flow through the
exhalatory conduit 230 to a pressure regulator 234.
[0054] In the preferred embodiment of the present invention the
pressure regulator 234, takes the form of discharging the flow of
exhalatory gases into a chamber 204 containing a column of water
238 as seen in FIG. 11. The gases flowing through the exhalatory
conduit 230 are discharged into the body of water 238 from a short
conduit 236 which extends from the expiratory conduit into the
chamber 204. This results in a bubbling effect, whereby the gases
eventually exit the chamber 204 via the outlet port 252, which can
also be used to initially fill the chamber 204 with water. The
outlet port 252 includes shielding to prevents liquid aerosols
created by the vigorous bubbling on the surface of the water from
being expelled. It will be appreciated that the short conduit 236,
could equally be integrated into the end of the expiratory conduit
230. It will also be appreciated that by adjusting the level of
which the short conduit 236 is submerged in the body of water 238
the mean pressure of supplied gases through the cannula 100 can be
controlled.
[0055] Nasal Cannula
[0056] Referring now to FIG. 4 to 10 the nasal cannula 100 is seen
in more detail. The inlet manifold 110, includes an inlet port 112.
This accepts the gas flow from the humidifier and air/oxygen
blender or any other flow source apparatus as would be appropriate.
The diameter of the inlet manifold 10 is as large as possible to
ensure minimal pressure drop in the gases before delivery to the
patient. In fluid communication with the inlet manifold are two
nasal prongs 116, 118. The gases are then able to flow from the
inlet manifold 10 up through the nasal prongs into the
corresponding nares of the patient. The prongs 116, 118 themselves
are cylindrical with a slight taper narrowing at the top. The
diameter is carefully chosen such that it will substantially seal
against the interior of the nare, without imparting any substantial
pressure thereon. As well as sealing this also provides some level
of securement and keeps the cannula 100 in place.
[0057] An important feature of the present invention is shown in
FIG. 2 and in more detail in FIG. 3. The two nasal prongs 116, 118
are spaced apart at a distance optimised for the nare spacing for a
neonatal infant. However the present invention would be equally
applicable for patients of all sizes and the design is easily
scalable. It will be appreciated that while the nasal structure of
each infant will be somewhat different, almost inevitably the
septum will be lower than the fleshy parts on the side of the nose.
As mentioned in the discussion of the prior art this may result in
irritation and pressure necrosis on the septum. It can be seen that
the inlet manifold 110 has a notch 126 or indentation in its
uppermost portion between the two nasal prongs 116, 118. The
indentation 126 is designed such that there will be no contact with
the septum.
[0058] Referring now particularly to FIG. 5 showing a sectional
view of the cannula 100. The inlet manifold 110 is separated from
the outlet manifold 130 by a partition 132 running horizontally the
length of both manifolds. The partition 132 terminates approximate
to the base 134 of the prongs 116, 118. In this fashion there will
always be at least some flow flowing directly from the inlet
manifold 110 to the outlet manifold 130. This ensures that the
deadspace or tidal volume is limited to the volume of the prongs
116,118. This configuration results in the minimum build up of
expired CO.sub.2 and also reduces any opportunity for condensation
in the cannula 100.
[0059] The prongs 116, 118 are made from a moulded rubber or
silicon insert 136 which has an interference or compression fit
seal to the hard plastic body 138 of the cannula 100. The prongs
are able to be used as a disposable component or alternatively
easily interchangeable for different sizes, a nasal mask,
mouthpiece or other interface as desired. The inlet port 112
connects directly to inlet manifold 110 and may be provided with
any typical connection configuration for commercially available
conduits. Similarly the outlet port 142 is in fluid communication
with the outlet manifold 130. A further sensor port 144 is provided
to measure any parameters of the delivered gases for example
pressure, temperature, humidity. An integral 10 mm inlet 10 mm
outlet conduit 154 formed from extruded PVC or silicon was found to
be suitable for this purpose. The sensor port 144 is connected to a
measurement tube 156 which may also form part of the integral inlet
outlet tube 154 connected to the cannula 100.
[0060] Head Securement
[0061] As can be seen in FIGS. 10 to 12 the cannula 100 is secured
to the neonates head by a bonnet overs its head. The infant bonnet
of the present invention includes a head covering portion 330 which
is preferably formed of a stretchable or elastic material having
thermal insulation property. An example of appropriate material is
a synthetic or cotton knit fabric. The head covering 330 is
provided in the form of a open ended tube. Where the material of
the covering 330 provides more stretch along one principal axis
then that principal axis as preferably aligned across the axis of
the tube.
[0062] The head covering 330 preferably includes a zone adjacent
one open end 332 which is stiffer than the surrounding region. The
zone 331 may comprise for example a region of modified knit form, a
cuff formed from an alternate material or material configuration or
a multi layer hem of the tube.
[0063] A securing device is provided on the outer surface of the
covering 330 for supporting a breathing tube or other medical
conduits or wiring.
[0064] The securing means is a strap 333 with which is sewn onto
the bonnet. The strap has Velcro attached at one end. The nasal
tubing is fitted with a foam block 334 with a triangular outside
shape. The foam block 334 is positioned on the strap 333. The strap
333 is then closed around the foam block and secured with the
Velcro. The foam block 334 is used to firmly hold the nasal tubing
321 in place on the bonnet 330 to prevent displacement of the nasal
prongs from the nares.
[0065] The second open end 347 of the head covering 330 is
preferably formed with a simple hem. The open end 347 is preferably
closeable or retainable in a closed position by a closing means
340. The closing means 340 may comprise a further lace or tie of
similar configuration to the securing means 333. The lace or tie
340 has two arms 342, 344. The arms 342, 344 preferably tie
together or pass through a toggle.
[0066] In use the end 347 of head covering 330 is bunched together
as an end bunch 341 The loop of lace or tie 340 is passed over the
bunch 341. The bunch 341 is firmly secured in a closed
configuration within the tightened loop of the lace or tie 340.
[0067] The closing means 340 thus provides for easy and efficient
closing or opening of the infant bonnet should there be a need for
access to the top of the head of the infant. Access may for example
be required for placement of electrodes or for cranial ultrasounds.
Where access is required the closing means 340 may be released and
the bunched portion of end 347 opened to provide necessary access.
This access is available without disturbing the other end 332 of
the head covering 330 or the securing means 333 supporting medical
tubes or wires in place.
[0068] Cannula Securement
[0069] Ideally the neonate should not be breathing out of it's
mouth. Both inhalation and exhalation should be done through the
cannula. In the preferred embodiment the neonates jaw is strapped
shut to eliminate mouth leak. Mouth leak is undesirable because it
causes a lower pressure thus reducing the level of CPAP.
[0070] Referring now particularly to FIGS. 8 to 10 we see that the
cannula 100 is secured at its base to the back of the neonates head
using strap 150. The strap connects at the base of the neonates
skull on the back of the neck. It connects to the cannula 100 by
way of a sliding strap 152. This strap is secured by way of clips
to the hard plastic body 138 allowing the securing strap 150
substantial relative movement with respect to the cannula 100 as
the neonate twists its head while providing adequate restraining
force directly on the cannula 100 without any twisting of the
cannula 100. In one embodiment this is accomplished by a plastic
e.g. acetal sliding strap which engages into sliding clips on the
outer face of the cannula. The teflon strap is adjustably attached
to the neck strap 150 to allow the tension to be adjusted to a
comfortable level.
[0071] What has been described is an improved nasal cannula for use
with a CPAP respirator. The improvement reduces the likelihood of
pressure necrosis or irritation that might normally be associated
with the use of such a device. The improvement ensures a balanced
feed to both prongs, low deadspace high flow through the manifold
so rebreathing of expired CO.sub.2 is minimised.
* * * * *