Note: Descriptions are shown in the official language in which they were submitted.
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[001] RESPIRATORY THERAPY SYSTEM INCLUDING
A NASAL CANNULA ASSEMBLY
This Application is a continuation-in-part of provisional application
No. 60/490,577 filed July 28, 2003 which is a continuation-in-part of
provisional
application No. 60/528,008 filed December 9, 2003 .
[002] FIELD OF THE INVENTION
[003] The present invention relates in general to respiratory assistance
equipment
and, in particular, to a respiratory therapy system including a nasal cannula
assembly for use in the administration of fluids such as oxygen into the nasal
passages of a patient having respiratory ailments.
[004] BACKGROUND OF THE INVENTION
[005] A variety of flexible cannulas have been produced that are positioned to
contact the nasal-labial area between the patient's upper lip and nostrils.
Even
though many of these cannulas were made of soft, flexible plastic, the wearer
frequently encountered discomfort because a cannula is usually worn for a
prolonged period of time. This results in continued contact of the cannula
with the
wearer's facial tissues, especially at the philtrum and around the unprotected
nasal-labial area, thereby causing irritation and inflammation.
[006] The structures of conventional cannula devices may be categorized into
two
general groups.
[007] The firstgroup utilizes a unitary member that includes a main
tubularportion
and a pair of tubular nasal prongs integrally connected to and in fluid
communication with the main tubular portion. The main tubular portion has
opposite ends which are connectable to flexible auxiliary oxygen supply tubes
that
are looped over the patient's ears and which themselves are in fluid
communication with a pressurized source of oxygen. As is known, the nasal
prongs are inserted into the nares of the wearer to deliver a!ow flow of
oxygen to
the patient's respiratory tract. The main tubular portion of these devices
spans
much if not all of the length of a wearer's upper lip. In so doing, the main
tubular
portion exerts contact pressure across much of the patient's upper lip. Under
these circumstances, a patient usually begins to experience discomfort in a
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relatively short period of time even if the cannula itself and the auxiliary
oxygen
supply tubes connected thereto are designed to deliver relatively low flows of
oxygen, i.e., they not particularly robust, stiff or heavy in weight. Examples
of
cannula devices and assemblies constructed in accordance with this first
group may be found in, for example, U.S. Patent Nos. 2,868,199; 3,643,660;
3,802,431; 4,106,505; 4,156,426; 5,400,776 and 5,794,619 and in published
U.S. Patent Application Publications Nos. U.S. 2001/0031929 Al and
U.S. 2002/0112730 Al.
[008] The second group involves a hamess member that does not itself convey
oxygen but which retains flexible auxiliary oxygen supply tubes in such a way
that
their discharge outlet ends define nasal prongs. However, the harness members
of these devices also typically span all or most of the length of a patent's
upper lip
whereby the devices, even for light-duty gas delivery applications, produce
the
same patient discomfort problems as the cannula devices of the first group.
Examples of cannula devices constructed according to the second group may be
found in, for examp;e, U.S. Patent Nos. 2,931,358; 3,400,714; 4,278,082;
4,648,398; 4,790,308; 4,818,320 and 5,533,506.
[009] Published United States Patent Application Publication No.
U.S. 2002/0046755 Al (the '755 publication) discloses various embodiments of
nasal cannulas that fall into one or the other of the aforementioned groups,
as well
as other embodiments that are not as readily classifiable. However, none of
the
nasal cannulas disclosed in that publication describe a device that would be
comfortable to a patient under the high flow conditions a patient would
experience
under positive airway pressure therapy, e.g., continuous positive airway
pressure
(CPAP) or bilevel positive airway pressure (BiPAP), that is often prescribed
to
patients suffering from Obstructive Sleep Apnea (OSA). For example, according
to one embodiment of cannula taught in the '755 publication, a relatively
narrow
connector member that would rest against a patient's upper lip is integrally
attached to the flexible auxiliary oxygen supply tubes whereby the ends of the
tubes would function as nasal prongs that elastically engage the user's nasal
septum inside of the nostrils. As used herein, the term "nasal septum," or
simply
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"septum," means the wall that divides the nasal cavity into halves which
terminate
at the nostrils. At its front or anterior portion the septum is a firm but
bendable
structure made mostly of cartilage that is covered by skin. In order to
deliver
respiratory gas flow to a cannula that would be therapeutically desirable to
maintain a typical adult patient's respiratory passageways open during OSA,
for
example, conventional auxiliary oxygen supply tubes must have an outerdiameter
of up to about 1/4 inch (0.635 cm). Tubes of this caliber, when inserted short
distances into the nostrils (as they must be so as not to harm the internal
nasal
tissues), would be quite obtrusive, stiff and uncomfortable to the user,
especially
when in elastic contact with the user's septum. Such discomfort would, in
turn,
detrimentally impact the patient's compliance with his or her prescribed
positive
airway pressure regime and, therefore, reduce the overall effectiveness of
therapy.
[010] U.S. Patent Nos. 4,782, 832; 5,042,478; 5,134,995; 5,269,296; 5,535,739;
5,687,715; 5,752,510; 6,431,172 and 6,478,026, as well as published United
States Patent Application Publication No. U.S. 2002/005935 Al, described nasal
cannulas for positive airway pressure therapy. However, the cannula devices
disclosed in these documents are quite large and cumbersome. Indeed, many are
designed to cover and/or seal the patient's nostrils. Consequently, they too
are not
conducive to optimum patient therapy compliance.
[011] An advantage exists, therefore, for respiratory therapy system including
a
nasal cannula assembly that is compact, lightweight and fabricated from highly
flexible material. So constructed, the assembly would be comfortable for
patients
that undergo respiratory therapy involving the administration of pressurized
respiratory gases for extended periods of time, including therapy involving
the
administration of pressurized respiratory gases at the high flow rates that
are
useful in positive airway pressure therapy.
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[012] SUMMARY OF THE INVENTION
[013] The present invention provides a respiratory therapy system including a
nasal cannular assembly adapted to contact the nasal-labial area of a
patient's
face. The cannula assembly comprises a nasal cannula, a pair of flexible
auxiliary
respiratory gas supply lines connected to the nasal cannula, a main
respiratory gas
supply line and, possibly a slip loop disposed about the auxiliary supply
lines.
[014] The nasal cannula is a unitary member desirably made of a highly
flexible
or pliable material. The cannula is molded so as to define a narrow central
member and a pair of flexible supply arms integrally formed along opposite
edges
of the central member that are connectable to pair of auxiliary respiratory
gas
supply lines. The inner ends of the supply arms define a pair of spaced-apart
hollow tubular extensions or prongs projecting in a slightly curved
configuration
from the central member. The tubular extensions are inserted into the nostrils
of
the wearer and their slightly curved configuration permits a positive guiding
of the
respiratory gas supply along the natural contours of the nasal passages into
the
pharynx.
[015] The upper surface of the central member is preferably rounded in order
to
minimize the area of contact on the lower, outer surface of the nasal septum
and
to avoid any straight or sharp edges that would concentrate pressure against
the
septum. This, coupled with the inherent flexibility and short length of the
central
member, allows the cannula to lightly contact a small portion of the nasal-
labial
area of the patient.
[016] In addition, the flexible supply arms of the cannula are designed such
that
when they are connected to the auxiliary respiratory gas supply lines and the
cannula assembly is properly donned by the patient, the arms flex in such a
way
as to urge the auxiliary respiratory gas supply lines to pass under, rather
than
across or above, the patient's cheekbones. The advantage of this effect is
that it
avoids the discomfort that some patients experience when nasal cannula
auxiliary
respiratory gas supply lines contact the tissues of their cheekbone
structures.
Thus, when the nasal cannula assembly of the present invention is subjected to
the pulling force of the auxiliary respiratory gas supply lines when the
assembly is
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worn by a patient, it exerts minimal pressure against the patient's nasal-
labial. In
addition, it provides positive positioning of the tubular extensions within
the nasal
passages while spacing their surfaces from the interior walls of the nasal
passages, including the septum. The result is a highly comfortable assembly
that
can be worn by a patient for long periods of time even under conditions of
high gas
flow rate whereby the patient is more likely to comply with and obtain the
optimum
benefits from his or her respiratory therapy regime.
[017] Another object of the present invention is to increase resistance to the
patient, upon exhalation, while not substantially increasing the breathing
work of
the patient during inhalation so that the breathing rate of the patient
remains
substantially at the same rate.
[018] Still another object of the present invention is to introduce a
sufficient
amount of a treating or a respiratory gas, such as oxygen, medicine, etc. (all
of
which hereinafter are referred to as a "respiratory gas") into the nasal
cavity of the
patient in order to dilute or blow or drive off much of the carbon dioxide, in
the
process of being exhaled by the patient during an exhalation breath, and
replace
that blown or driven off carbon dioxide with the respiratory gas which can
thereafter be readily inhaled by the patient during his/her subsequent
inhalation
breath.
j019] Yet another object of the present invention is to provide a respiratory
gas
supply system which is readily retained within the nostrils of a patient while
still
being received therein so as to facilitate leakage between the inwardly facing
nostril skin and the exterior surfaces of the nasal prongs to permit blowing
or
driving off some of the carbon dioxide contained within the exhalation breath
of the
patient.
[020] A still further object of the present invention is to normally provide
an excess
quantity of the respiratory gas to the patient, at a constant flow rate, while
allowing
some of the excess respiratory gas to leak between the inwardly facing nostril
skin
and the exterior surfaces of the nasal prongs.
[021] Another object of the present invention is to design a respiratory gas
supply
system which adequately heats and moisturizes the respiratory gas, prior to
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delivering the same to the patient, while also minimizing any condensation,
along
the supply conduit, of moisture contained in the respiratory gas and also
reducing
the noise generated by the respiratory gas supply system, to a decibel level
approaching about 46 decibel, during delivery of the respiratory gas.
[0221 A further object of the present invention is to generate and maintain a
sufficient back pressure in the patient, utilizing the respiratory gas supply
system,
so that the soft palate of the patient remain sufficiently inflated and are
prevented
from collapsing.
[0231 Still another object of the present invention is to provide a
respiratory gas
supply system which is able to sleep apnea.
[024] The present invention relates to a nasal cannula for supplying a
respiratory
gas to a patient, the nasal cannula comprising: a pair of supply lines which
each
have a head at one end thereof with a discharge opening therein for
discharging
a respiratory gas, and the opposite end of each of the pair of supply lines
being
connectable to a respiratory gas source; wherein each head is sized to be
snugly
received and retained within one of the nasal cavities of the patient while
forming
a sufficient leakage passage, between a portion of inwardly facing nasal
cavity skin
of a patient and a portion of an exterior surface of the head, to facilitate
exhausting
of any excess respiratory gas supplied to the patient through the leakage
passage
and also facilitate inhalation of any room air required in excess of the
respiratory
gas to be supplied to the patient.
[025] The present invention relates to a nasal cannula assembly for supplying
a
respiratory gas to a patient, the nasal cannula assembly comprising: a pair of
supply lines which each have a head at one end thereof with a discharge
opening
therein for discharging a respiratory gas, and the opposite end of each of the
pair
of supply lines being connected to an auxiliary respiratory gas supply line;
and a
remote end of each of the auxiliary respiratory gas supply line is connected
with
a respiratory gas source for supplying a respiratory gas to a patient; wherein
each
head is sized to be snugly received and retained within one of the nasal
cavities
of the patient while forming a sufficient leakage passage, between a portion
of
inwardly facing nasal cavity skin of a patient and a portion of an exterior
surface
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of the head, to facilitate exhausting of any excess respiratory gas supplied
to the
patient through the leakage passage and also facilitate inhalation of any room
air
required in excess of the respiratory gas to be supplied to the patient.
[026] The present invention relates to a respiratory therapy system for
supplying
a respiratory gas to a patient via a nasal cannula, the respiratory therapy
system
comprising: a source of respiratory gas for supplying a respiratory gas to a
patient;
a nasal cannula connected to the source of respiratory gas for receiving the
respiratory gas and supplying the respiratory gas to nostrils of a patient;
the nasal
cannula comprising: a pair of supply lines which each have a head at one end
thereof with a discharge opening therein for discharging a respiratory gas,
and the
opposite end of each of the pair of supply lines being connected to an
auxiliary
respiratory gas supply line; and a remote end of each of the auxiliary
respiratory
gas supply line is connected with a respiratory gas source for supplying a
respiratory gas to a patient; wherein each head is sized to be snugly received
and
retained within one of the nasal cavities of the patient while forming a
sufficient
leakage passage, between a portion of inwardly facing nasal cavity skin of a
patient and a portion of an exterior surface of the head, to facilitate
exhausting of
any excess respiratory gas supplied to the patient through the leakage passage
and also facilitate inhalation of any room air required in excess of the
respiratory
gas to be supplied to the patient.
[027] The present invention relates to a method of treating a patient with
sleep
disorder with a respiratory gas, the method comprising the steps of: inserting
prongs of a nasal cannula within respective nostrils of the patient; supplying
a
respiratory gas to the nasal cannula at a constant flow rate sufficient to
form a
back pressure within the breathing passageways of the patient, at least when
the
patient is exhaling; and allowing, at least during exhalation, a portion of
the
supplied respiratory gas to leak from the nostril between the prongs of the
nasal
cannula and inwardly facing skin of the nostril.
[028] The present invention relates to a diagnostic tool for measuring nasal
cavity
pressure of a patient, the diagnostic tool comprising a the nasal cannula
comprising: a pair of supply lines which each have a head at one end thereof
with
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a discharge opening therein for discharging a respiratory gas, and the
opposite
end of each of the pair of supply lines being connectable to a respiratory gas
source; each head being sized to be snugly received and retained within one of
the
nasal cavities of the patient while forming a sufficient leakage passage,
between
a portion of inwardly facing nasal cavity skin of a patient and a portion of
an
exterior surface of the head, to facilitate exhausting of any excess
respiratory gas
supplied to the patient through the leakage passage and also facilitate
inhalation
of any room air required in excess of the respiratory gas to be supplied to
the
patient; pressure sensing probe associated with each head; and each of the
pressure sensing probe is coupled to supply a pressure reading to a pressure
sensing device.
[029] The present invention relates to a method of using a diagnostic tool for
measuring nasal cavity pressure of a patient, the method comprising the steps
of:
permitting a patient to sleep; monitoring the sleeping patient with a
diagnostic tool
while a respiratory gas is supplied to a patient at a first flow rate;
determining a
pressure within the nasal cavity of the patient via a pressure sensing probe
of the
diagnostic tool; and adjusting the flow rate of the respiratory gas until an
optimum
respiratory gas flow rate is achieved which generates a desired back pressure
within the breathing passages of the patient so that the patient uniformly
breathes
while sleeping.
[030] As used in this patent application and in the appended claims, sleep
apnea,
obstructed sleep apnea, oxygen desaturation, and other related breathing
interruptions, etc., all herein after referred to as "sleep disorder".
[031] As used in this patent application and in the appended claims, the term
"constant flow rate" means that the supply of the respiratory gas to the
patient
must be at a sufficient flow rate to be efficacious, e.g., generate a desired
back
pressure within the breathing passageways of the patientto facilitate
breathing, not
being excess so as to provide discomfort to the patient.
(032] As used in this patent application and in the appended claims, the term
"trough" means an opening, passageway, indentation or some other exterior
surface irregularity such as, for example, a channel, a groove, a slot, a
flute, or the
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like which facilitates leakage, in either flow direction, between the inwardly
facing
nasal cavity skin of a patient and the exterior surface of the head of the
cannula.
[033] As used in this patent application and in the appended claims, the term
"supply line" means an arm, a conduit, a tube, a duct, a channel, or some
other
confined flow path for supplying a respiratory gas from a source to a patient.
[034] Other details, objects and advantages of the present invention will
become
apparent as the following description of the presently preferred embodiments
and
presently preferred methods of practicing the invention proceeds.
[035] BRIEF DESCRIPTION OF THE DRAWINGS
[036] The invention will become more readily apparent form the following
description of preferred embodiments thereof shown, by way of example only, in
the accompanying drawings where:
[037] Fig. 1 is an enlarged elevational view of a portion of a cannula
assembly
according to the present invention in operative position on a patient;
[038] Fig. 2 is an elevational view of a complete cannula assembly according
to
the present invention in an operative position on a patient;
[039] Fig. 3 is a rear elevational view of the cannula of the cannula assembly
according to the present invention;
[040] Fig. 4 is an enlarged cross-sectional view taken along line 4-4 of Fig.
3
showing the relative position of the cannula of Fig. 3 when secured to a
patient
with its extensions inserted into the patent's nasal cavity;
[041] Fig. 5 is a top plan view of the cannula of Fig. 3;
[042] Fig. 6 is a block diagram of a respiratory therapy system including a
nasal
cannula assembly according to the present invention;
[043] Fig. 7 is a diagrammatic view of another embodiment of the respiratory
therapy system;
[044] Fig. 8 is a block diagram of another embodiment of a respiratory therapy
system including a nasal cannula assembly according to the present invention;
[045] Fig. 9 is a front elevational view of a variation of the nasal cannula;
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[046] Fig. 9A is a diagrammatic view of the nasal cannula of Fig. 9 in the
direction
of section line 9A-9A of Fig. 9;
[047] Fig. 9B is a diagrammatic front view showing the two heads of the nasal
cannula received within the nostrils of a patient to define a plurality of
leakage
passages therebetween;
[048] Fig. 9C is a diagrammatic side view of Fig. 9B showing the one of the
two
heads of the nasal cannula received within the nostrils of a patient;
[049] Fig. 10 is a front elevational view of another variation of the nasal
cannula;
[050] Fig. 10A is a diagrammatic view of the nasal cannula of Fig. 10 in the
direction of section line 10A-10A of Fig. 10;
[051] Fig.10B is a diagrammatic view showing the two heads of the nasal
cannula
received within the nostrils of a patient to define a plurality of leakage
passages
therebetween;
[052] Fig. 11 is a diagrammatic cross sectional view of a swivel for use with
the
respiratory gas supply lines of the respiratory therapy system;
[053] Fig. 12 is a front elevational view of a diagnostic tool incorporated
into the
cannula of the present invention;
[054] Fig. 12A is a diagrammatic view of the diagnostic tool of Fig. 12 in the
direction of section line 12A-12A of Fig. 12;
[055] Fig. 12B is a front elevational view of the diagnostic tool of Fig. 12
showing
each of the pressure sensing probe coupled to a separate pressure sensing
device;
[056] Fig. 13 is a diagrammatic view of a housing incorporating the various
internal heating, moisturizing and control components of the respiratory
therapy
system;
[057] Fig. 13A is a diagrammatic view depicting the internal heating,
moisturizing
and control components of the housing of Fig. 13;
[058] Fig. 13B is a diagrammatic cross sectional view of the post heater of
Fig. 13;
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[059] Fig. 14 is a diagrammatic longitudinal cross sectional view of a section
of
a corrugated tube or some conventional insulating wrap or material for the
respiratory gas supply line;
[060] Fig. 14A is a diagrammatic cross section view along section line 14A-14A
of Fig. 14;
[061] Fig. 15 is a diagrammatic cross sectional view of a slip loop to control
tensioning of the pair of auxiliary respiratory gas supply lines; and
[062] Fig. 15A is a diagrammatic top plan view of the slip loop of Fig. 15.
[063] DETAILED DESCRIPTION OF THE INVENTION
[064] Referring to the drawings wherein like or similar references indicate
like or
similar elements throughout the several view, a nasal cannula assembly,
according
to the present invention, generally designated by reference numeral 10, is
shown
in Figs. I and 2 in an operative position on a patient's face. The nasal
cannula
assembly 10 comprises a nasal cannula 12, a pair of auxiliary respiratory gas
supply lines 14 connected to supply lines or arms 26 of the cannula (described
below in further detail), a main respiratory gas supply line 16, a connector
18 for
coupling each of the auxiliary lines 14 to the main respiratory gas supply
line 16,
an optional slip loop or line tightening member 20 disposed about auxiliary
lines
14 for faciiitating adjustment of the auxiliary lines about the patient's ears
and
head, and an end connector 22 for facilitating connection of a second end of
the
main respiratory gas supply line 16 to a pressurized respiratory or
respiratory gas
source 23. As described in greater detail below with reference to Fig. 6, the
pressurized respiratory or respiratory gas source 23 comprises a compressor
for
delivering pressurized air (such as is commonly used in the treatment of OSA).
Depending on a patient's therapeutic needs, a respiratory therapy system
including
the pressurized respiratory or respiratory gas source 23 may deliver heated
and
humidified respiratory gas to a patient.
[065] Cannula 12 is generally a unitary member that may be fabricated by any
suitable molding process such as, for example, by a dip molding process.
Examples of dip molding processes for cannula formation include those
disclosed
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in U.S. Patent Application Serial Nos. 09/754,471 and 09/883,843 (both of
which
are entitled "Method to Produce Nasal and Oral Cannula Breathing Detection
Devices") and the disclosures thereof are incorporated herein by reference in
their entireties. The composition of cannula 12 is preferably a thermoplastic
composition such as polyvinyl chloride, polyvinyl acetate, polyethylene, soft
latex
or other materials that are highly pliable or flexible.
[066] As most clearly illustrated in Figs. 1, 3 and 5, cannula 12 comprises a
narrow or short-length central bridge member 24 which spaces apart a pair of
substantially right angle flexible supply arms 26. The ridges of the supply
arms 26
are integrally connected to the central bridge member 24 along opposite side
end
edges 28 thereof (as shown in Fig. 3) and the second ends of the supply arms
26
are respectively connectable to one of the auxiliary respiratory gas supply
lines 14
(as shown in Figs. 1 and 2). The connection between supply arms 26 of
cannula 12 and auxiliary respiratory gas supply lines 14 may be effectuated by
any
suitable method or means and the connection may be either releasable or
permanent. For example, according to a presently preferred embodiment, the
supply arms 26 are intimately received within the auxiliary respiratory gas
supply
lines 14 and their connections may be maintained by friction fit, a solvent,
adhesive
bonding, ultrasonic welding, etc.
[067] As shown in Figs. 4 and 5, a nozzle or hollow tubular extension 30 is
integrally formed with and project upwardly from the ridge of each of the
supply
arms 26. Each tubular extension 30 preferably assumes a slightly curved
configuration, corresponding substantially to that of an anterior region of a
patient's
nasal cavity, and terminates in a respiratory gas discharge outlet 32. For
optimum
patient comfort, each tubular extension 30 preferably tapers upwardly from the
top
of the central bridge member 24 to the discharge outlets 32. In operation,
each
tubular extension 30 is inserted into one of the nostrils of the patient so as
to
extend into the nasal cavity N. The curved configuration of the tubular
extensions 30 permits a positive guiding of the respiratory gas supply along
the
natural contours of the nasal passages into the pharynx P rather than toward
the
upper reaches of the nasal cavity where the respiratory gas may cause pressure
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and potentially irritate the patient. In addition, there are no sharp edges
along or
at the tip of the tubular extensions 30 which could irritate the nasal passage
due
to the movements induced by patient breathing and the soft, flexible material
of the
cannula permits the extensions to easily conform to the contours of the nasal
cavity N.
[068] Unlike some conventional nasal cannulas that possess structure which
spans most, if not all of a patient's upper lip, the central bridge member 24
of
cannula 12 is quite narrow and has a relatively short axial length. Indeed, it
is
configured to span substantially no more than the width of the patient's
philtrum 34
(Fig. 1). As a result, a minimal area of the front surface of the patient's
upper lip
is in continuous contact with a rear surface of the central bridge member 24
and
the cannula 12 during use of the cannula. Additionally, as shown in Fig. 4,
the
upper surface of central bridge member 24 is preferably rounded in order to
minimize the area of contact on the lower, outer surface of the nasal septum
and
to avoid any sharp or straight edges that may concentrate pressure
thereagainst.
Thus, the combination of these features causes the cannula 12 to lightly
contact
a small portion of the nasal-labial of the patient, thereby enhancing both the
comfort to a patient who must wear a nasal cannula 12 for prolonged periods of
time and the patient's willingness to comply with his/her CPAP therapy
program.
[069] Figs. 1 and 2 illustrate the preferred manner in which the cannula
assembly 10 is to be worn by a patient. The cannula 12 generally rests across
the
patient's nasal-labial area while the flexible auxiliary respiratory gas
supply lines 14
initially extend across the patient's face, over and behind the patient's
ears, down
the haw areas and are brought together under the chin of the patient. The line
tightening member 20, which is of sufficient size to encompass both of the
auxiliary
supply lines 14, may then be adjusted along the length of the auxiliary supply
lines 14 so that the cannula 12 will remain firmly in place without the
auxiliary
supply lines 14 being uncomfortably taut on the patient.
[070] As depicted in Fig. 5, the central bridge member 24 of cannula 12,
according to one construction, defines a horizontal plane X. Each of the
supply
arms 26 lie on one side of the horizontal plane X and lie in a respective
horizontal
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plane X' that forms an acute angle a relative to the horizontal plane X of the
central bridge member 24. Disposing the supply arms 26 at an angle a, with
respect to the horizontal plane X of the central bridge member 24, serves to
minimize the amount of tension and/or force that must be applied to the
auxiliary
respiratory gas supply lines 14 to maintain the cannula 12 in position against
the
patient's nasal-labial.
[071] Additionally, as shown in Fig. 3, the opposite end of each of the supply
arms 26 initially extends away from the ridge and the central bridge member 24
and then bends and turns outwardly away from one another to the second end in
a gently curved configuration having a radius of curvature of about 0.4 inch
to
about 0.8 inch depending on the facial characteristics and head size of the
patient
that will use the device, e.g., child or adult. Although supply arms 26 are
highly
flexible and yieldable they nevertheless possess sufficient resilience or
stiffness
to impart a desirable configuration to the auxiliary supply lines 14 which
further
enhances the patient's comfort. That is, the curved supply arms 26 function to
urge the auxiliary respiratory gas supply lines 14 to pass beneath and around,
rather than across or over, the patient's cheekbone areas 36 (Fig. 1). This
arrangement advantageously avoids the discomfort that some patients experience
when the nasal cannula auxiliary respiratory gas supply lines contact their
cheekbone areas 36. Thus, when the nasal cannula assembly 10 of the present
invention is subjected to the pulling force of the auxiliary respiratory gas
supply
lines 14 when the assembly is worn by a patient (which pulling force is
greater for
larger caliber and stiffer auxiliary respiratory gas supply lines that are
designed to
deliver high respiratory gas flows), it exerts minimal pressure against both
the
patient's nasal-labial 34 and cheekbone areas 36.
[072] As mentioned above, the nasal can nula assembly 10 is beneficial whether
it is used to convey respiratory gases under low flow rates, such as might be
administered for oxygen assistance therapy, or high flow rates of at least
about 28
liters per minute, as might be required for positive airway pressure
administration
for treatment of OSA. In any event, the dimensions of the main respiratory gas
supply line 16, the auxiliary respiratory gas supply lines 14 and the cannula
supply
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arms 26 will be optimized to provide minimum bulk and weight, minimal pressure
drop, maximum flow and minimum turbulence and noise generation. In addition,
it will be understood that the nasal cannula 12 may be molded to any
dimensions
suitable to accommodate the particular physical facial characteristics and
sizes of
a patent ranging in size from very small children or infants to very large
adults.
The result is a highly comfortable assembly that can be worn by a patient for
long
periods of time even under conditions of high gas flow rates whereby the
patient
is more likely to comply with and obtain the optimum benefits of his or her
respiratory therapy regime.
[073] Fig. 6 illustrates, in general, a respiratory therapy system 40
including a
pressurized respiratory or respiratory gas source 23 for supplying the
respiratory
gas to the system 40 and the patient P, and a nasal cannula assembly 10
according to the present invention. The respiratory therapy system 40,
described
in further detail below, can be generally defined as an open system providing
a
high flow of a respiratory gas to the patient P. An open system is generally
open
to the effects of ambient air pressure. As is readily apparent to one skilled
in the
art, this occurs adjacent the discharge opening 32 of the nasal cannula
assembly 10 where the respiratory gas flow is introduced into the nostrils of
the
patient's nose and a portion of the respiratory gas along with a portion of
the
exhaled gases of the patient, is allowed to leak out through the
nostril/tubular
extension interface.
[074] In contrast to the open respiratory therapy system 40 of present
invention,
the previously known sleep apnea gas delivery systems are, in general, closed
systems which provide a respiratory gas at a specified higher pressure
relative to
the ambient air pressure. In such closed systems, a face mask is sealed over
the
mouth and/or nose of the patient P, thus creating the closed pressure system.
A closed gas delivery system may generate pressures in the range of 4 to 20 cm
H20 in the patient's respiratory passages to maintain open airways. The sealed
mask is, of course, worn by the patient while he/she is sleeping. However, the
sealed mask and the pressure developed thereby with the delivered respiratory
gas are particularly uncomfortable to the patient and the treatment is often
CA 02534750 2006-01-26
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prematurely abandoned by the patient after several sessions due to a variety
of
reasons, e.g., discomfort of the mask, etc.
[075] In many cases of sleep apnea, the burden and effect of such closed
systems is not necessary. The open respiratory therapy system 40 of the
present
invention overcomes the above noted drawbacks of known closed therapy
systems. The above described nasal cannula assembly 10 is substantially more
comfortable for the patient to wear then the masks used in known sleep apnea
treating systems. Thus, the patient is less apt to remove the mask and forego
the
therapy due to discomfort. The delivery of a high flow of respiratory gas to
the
patient's airways ensures that there is an abundance of the respiratory gas
available to the patient which is delivered at 3 to 15 cm of H20 pressure.
[076] In general, as shown by the heavy black arrows of Fig. 6 as well as in
Fig. 7,
the respiratory therapy system 40 of the present invention supplies a
respiratory
gas from a source 23 to an initial gas flow developing/measuring mechanism 44
for imparting a desired high flow rate of the respiratory gas through a
remainder
of the respiratory therapy system 40 to the nasal cannula assembly 10 and into
the
patient's upper respiratory system. The high flow rate permits the patient's
lungs
to freely draw in the respiratory gas, and the high flow rate of respiratory
gas
provides a rich, abundant source of the respiratory gas without the need for
developing a significant over pressure in the patient's lungs by using a mask
to
cover the patient's mouth and nose. The flow developing/measuring mechanism
44, for developing the desired respiratory gas flow rate, can be, for example,
a
compressor, a fan, a pump, a blower or some other conventional device which is
well known in the art. The flow developing/measuring mechanism 44 typically
will
supply the respiratory gas at a rate of from about 26 to about 60 liters per
minute,
preferably about 50 liters per minute, at a pressure of from between 3 and 15
cm
of H20.
[077] The respiratorygas generally is conditioned priorto deliveryof the same
to
the patient. Generally a humidifier 50 is provided for conditioning the
respiratory
gas prior to delivery to the patient. The respiratory gas is typically warmed
and
humidified in order to minimize and/or avoid patient discomfort and possibly
harm
CA 02534750 2006-01-26
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to the internal tissues of the patient's nasal cavity. In particular,
respiratory gas
supplied at the above described flow rates should be maintained at a relative
humidity of about 70 percent and 100 percent and more preferably at a relative
humidity of about 80 percent. Additionally, the temperature of the supplied
gas
should be within the range of about 81 F (27.2 C) and about 90 F (32.2 C) and
more preferably at a temperature of about 86 F (30.0 C).
[078] High flow conditions may also tend to create noise and turbulence in the
auxiliary gas supply lines 14 and/or the supply arms 26 which may cause
annoyance and/or discomfort to the patient and may be detrimental to the
patient's
long term use of the system. In order to minimize noise and turbulence, the
components of the nasal cannula assembly 10, the auxiliary respiratory gas
supply
lines 14 and the main respiratory gas supply line 16 typically have an inner
diameter of about 0.173 or 3/16 inch (0.068 cm) and an outer diameter of
about 0.225 or 7/32 inch (0.088 cm), although other sizes are also
contemplated
and would be readily apparent to those skilled in the art. It is also possible
to
utilize ribbon supply conduit as long as the respiratory gas supply lines are
sufficiently sized to satisfy the gas delivery conditions and prevent or
minimize
kinking thereof.
[079] In the case of a specially prepared respiratory gas, a check valve or
some
other suitable supply gas metering device 46 is preferably provided, as part
of the
respiratory gas source 42, to conserve use of the respiratory gas. The
respiratory
gas is thus supplied via the metering device 46 to the flow
developing/measuring
mechanism 44. The flow developing/measuring mechanism 44 typically supplies
the respiratory gas to the humidifier 50, for adequately humidifying the
respiratory
gas, and then to the heater 47, for adequately heating the respiratory gas,
before
finally supplying the same via the nasal cannula assembly 10 to the patient P.
[080] A controller 56 is used to control the flow parameters of the
respiratory
therapy system 40, e.g., monitor the desired flow, as selected by the user, or
as
required by the ramp or re-ramp functions. The controller 56 provides
adjustment
for varying the respiratory gas flow rate from about 26 to 60 liters per
minute,
preferably about 50 liters per minute, over a period of from about 5 minutes
to 30
CA 02534750 2006-01-26
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minutes, to enable the patient to acclimate to the desired flow rate (ramp
function).
This ramp function can be used for both initial cold startups and hot
interrupted
sleep starts.
[081] Additionally, the controller 56 continuously monitors the respiratory
gas
temperature and provides an input to the humidifier 50 and the heater 47 to
control
individually both the humidity and/or temperature of the supplied respiratory
gas.
The controller 56 also monitors and provides control of the temperature
throughout
the ramp functions so as to maximize patient comfort. The controller 56 is
provided with control logic circuits to monitor and control these various
aspects of
the respiratory therapy system 40 and as such control logic circuits are
conventional and well known in the art, a further detail discussion concerning
the
same is provided.
[082] A number of other devices may also be provided to supply different
inputs
to the controller 56. For example, an ambient temperature sensor 66 may supply
the ambient temperature to the controller 56 to optimize the temperature of
the
respiratory gas relative to the patient's ambient temperature surroundings.
Also, the respiratory therapy system 40 may include an ambient humidity
sensor 67 for sensing the ambient humidity to assist with a more effective
control
of the humidity of the respiratory gas leaving the humidifier 50.
[083] In a still further embodiment of the present invention, as shown in Fig.
8, the
respiratory therapy system 40 may provide the respiratory gas, either before
or
after passing through 60 liters per minute, preferably about 50 liters per
minute, a
flow developing/measuring mechanism 44, through a pass over humidifier 70, or
some other type of humidifier known in the art provided with variable heat
control
to more efficiently manage humidification and increase water vapor in the
respiratory gas. The humidified respiratory gas is then conveyed to a heater
(e.g.,
a post heater) 48 and subsequently supplied to the nasal cannula assembly 10
for
delivery to the patient P. Again, as discussed above, the controller 56 is
used to
monitor and control the system components, namely, the flow
developing/measuring mechanism 44, the humidifier 70 and the heater (e.g., a
post heater) 48 to adequately control the temperature and humidity of the
CA 02534750 2006-01-26
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respiratory gas before delivery to the patient. A temperature measurement
sensor
58 may be provided in the respiratory therapy system 40, after the heater
(e.g., a
post heater) 48, and the ambient room temperature sensor 66 and the ambient
room humidity sensor 67 may provide the controller 56 with inputs to assist
with
ensuring that the respiratory gas is controlled at a desired temperature and
humidity level prior to delivery to the patient P.
[084] Preferably the respiratory gas, once being sufficiently heated and
humidified
by the respiratory therapy system 40 just prior to delivery to the patient,
typically
is delivered at a relative humidity of between 70 and 100 percent and more
preferably a relative humidity of about 85 percent.
[085] With respect to heating of the respiratory gas, a post heating
arrangement
is preferred as it heats up and cools down relatively quickly thereby
facilitating
more accurate control of the temperature of the respiratory gas being supplied
to
the patient.
[086] With reference to Figs. 9-9C, a further variation of the invention will
now be
described. As this embodiment is quite similar to the previous embodiment,
only
the differences between this embodiment and the previous embodiment will be
discussed in detail. According to the embodiment, the prong end of each supply
arm 26 includes an enlarged head 72 which contains the respiratory gas
discharge
outlet 32. The head 72 preferably has an elliptical transverse cross sectional
shape (see Figs. 10-10B) which facilitates both insertion and removal of the
head
72 as well as retention thereof within the nostril of the patient. The maximum
diameter of the elliptically shaped head may be slightly compressed as the
head
72 is received within in the respective nostril and such slight compression of
the
head 72 leads to improved retention of the head 72 within the nostril without
any
perceived discomfort to the patient. Alternatively, the diameter of the head
72 may
be substantially cylindrical in shape as is shown in Figs. 7-9C. At least one
and
preferably a plurality of equally spaced apart elongate channels, grooves,
slots,
troughs or flutes 74 are formed in the exterior surface of the head 72. Each
one
of these elongate channels, grooves, slots, troughs or flutes 74 extends
substantially parallel to, but is spaced from, a longitudinal axis A of the
tubular
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extension 30 to facilitate exhausting of any excess supplied respiratory gas
from
the nasal cavity as well as permitting inhalation by the patient of any
required
additional air needed by a patient during inhalation. Each elongate channel,
groove, slot, trough or flute 74 generally is defined by a pair of adjacent
side
surfaces 75, diverging from a common elongate valley 76, toward the pair of
adjacent elongate ridges 78. In the first version of the head 72 (e.g., the
larger
model) shown in Figs. 9-9B, the head 72 has a maximum outer diameter of
between about 0.50 of an inch (1.3 cm) and about 0.70 of an inch (1.8 cm),
preferably about 0.60 of an inch (1.5 cm) and has an axial length of between
about
0.5 of an inch (1.3 cm) and about 0.60 of an inch (1.5 cm), preferably about
0.55
of an inch (1.4 cm) so that the head 72 is readily received and retained
within a
nostril 71 of a patient having a relatively large nostril (see Figs. 9B and
9C).
According to this embodiment, the enlarged head 72 has eight elongate
channels,
grooves, slots, troughs or flutes 74 equally spaced about the circumference of
the
head 72. Each valley 76 has a depth of between about 0.03 of an inch (0.08 cm)
and about 0.06 of an inch (0.15 cm), preferably about 0.05 of an inch (0.13
cm).
[087] According to a second version of shown in Figs. 10-10B, e.g., a
"smaller"
version of the enlarged head 72, the head 72 has a maximum outer diameter of
between about 0.345 of an inch (0.88 cm) and about 0.375 of an inch (0.95 cm),
preferably about 0.355 of an inch (0.90 cm) and has an axial length of between
about 0.30 of an inch (0.76 cm) and about 0.375 of an inch (0.95 cm),
preferably
about 0.35 of an inch (0.9 cm) so that the head 72 is readily received within
a
nostril 71 of a patient having relatively a smaller sized nostril (see Fig.
1013).
According to this embodiment, the enlarged head 72 has six elongate channels,
grooves, slots, troughs or flutes 74 equally spaced about the circumference of
the
head 72. Each valley 76 has a depth of between about 0.015 of an inch (0.04
cm)
and about 0.035 of an inch (0.09 cm), preferably about 0.025 of an inch (0.06
cm).
[088] It is to be appreciate to those skilled in this art that numerous
variations
concerning the number, the shape, the depth, the width, the size, the cross
sectional leakage area, etc., of the elongate channels, grooves, slots,
troughs or
flutes 74 and leakage passageways 81 would be readily apparent to those
skilled
CA 02534750 2006-01-26
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in the art depending upon the particular application. In view of this, a
further detail
description concerning such variations and/or modifications of the enlarged
head 72, the side surfaces 75, the valleys 76, the elongate ridges 78 and/or
the
leakage passageway 81 is not provided herein but such numerous variations are
considered to be within the spirit and scope of the present invention.
[089] As the ridge of the nasal cannula 12 is received within the respective
nostrils 71 of a nose 73 of the patient (see Figs. 9B, 9C and 10B), the
elongate
valleys 76 of the nasal cannula 12 have a diameter which are sized to be
slightly
smaller than the perimeter opening of the nostril 71 of the patient so that a
plurality
of circumferentially spaced leakage passageways 81 are formed. Each one of the
leakage passageways 81 is formed and defined by the pair of adjacent side
surfaces 75, diverging from a common elongate valley 76 toward the pair of
adjacent elongate ridges 78, and the inwardly facing skin tissue 69 of the
nostril
71. For the large head 72 (see Figs. 9-9B), the adjacent side surfaces 75,
diverging from a common elongate valley 76, and the inwardly facing skin
tissue
69 of the nostril 71 together define a cross sectional open area or leakage
passageway 81 of between about 0.0045 square inches (0.029 cm2) and 0.0055
square inches (0.035 cm2), and preferably define a cross sectional open area
or
leakage passageway 81 of about 0.005 square inches (0.032 cm2). For the
smaller head 72 (see Figs. 10-10B), the adjacent side surfaces 75, diverging
from
a common elongate valley 76, and the inwardly facing skin tissue of the
nostril 71
together define a cross sectional open area or leakage passageway 81 of
between
about 0.002 square inches (0.013 cm2) and 0.003 square inches (0.019 cmZ), and
preferably define a cross sectional open area or leakage passageway 81 of
about
0.0025 square inches (0.016 cm2).
[090] The head 72 is sized to facilitate retention of the nasal cannula 12
within a
nostril 71 of a patient while the leakage passageways 81 prevent a fluid tight
seal
from being formed, between the exterior surface of the enlarged head 72 of the
nasal cannula 12 and the inwardly facing skin tissue 69 of the patient's
nostril 71,
so as to continuously allow any excess respiratory gas supplied to the nasal
cavity
to be exhausted out therethrough. The leakage passageways 81 also continuously
CA 02534750 2006-01-26
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allow room air to flow inwardly therethrough in the event that additional air,
for
breathing by the patient in excess to the constant flow rate of the
respiratory gas
currently being supplied by the respiratory therapy system 40, is required
during
inhalation, e.g., at a peak negative pressure generated by the patient during
inhalation. By this arrangement, the respiratory therapy system 40 is able to
generate a sufficient resistance or back pressure within breathing passages of
the
patient, during exhalation, so that the breathing passages of the patient
remain
adequately open and/or inflated without significantly increasing the work
required
by the patient during each inhalation and exhalation breath.
[091] As is known in the art, a normal human being typically has a blood 02
concentration level of between 94% and 97%. One major respiratory problem
plaguing numerous human beings worldwide is commonly known as sleep apnea,
e.g., a condition where the O2 concentration level in the patient's blood is
about 88 percent or less.
[092] The respiratory therapy system 40, according to the present invention,
is
readily able to treat both mild and moderate OSA and is also successful in
treating
severe OSA. During operation of the respiratory therapy system 40, the gas
supply flow rate remains constant during the entire treatment period. That is,
the
respiratory therapy system 40 does not vary the flow rate of the supplied
respiratorygas due to any variation in the leakage of the system as typically
occurs
with the prior art devices and systems. Nevertheless, the supplied flow rate
of the
supplied respiratory gas is sufficient to dilute and/or diffuse the CO2 which
is in the
process of being exhaled by the patient, during an exhalation breath, while
still
maintaining an adequate resistance or back pressure in the patient's breathing
passages so that the bronchi, the trachea, the lungs, etc., all remain
sufficiently
inflated during exhalation and upon commencement of a subsequent inhalation
breath to thereby facilitate a more complete discharge or exhausting of the
exhaust
or byproduct gases, e.g., C02, from the patient while still maintaining a
relatively
low work of breathing for the patient during inhalation.
[093] The respiratory therapy system 40 typically delivers the respiratory gas
at
a flow rate of between about 26 and about 60 liters per minute, preferable
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about 50 liters per minute at a pressure of between about 3 to 15 cm of water.
Such flow conditions of the respiratory gas are generally adequate to create
and
maintain a sufficient back pressure in the breathing passages of the patient
so that
the breathing passages remain sufficiently open and do not collapse, during an
exhalation breath of a patient. It is to be appreciated that if the breathing
passages
of the patient coltapse, such collapse tends to prevent complete exhalation of
CO2
and/or any other patient byproduct gases and thereby traps the same within the
breathing passages of the patient. Since, according to the present invention,
the
breathing passages of the patient are essentially prevented from collapsing
and/or
become sufficiently obstructed, during the exhalation, the normal gas exhaust
airway passages, from the alveoli to the nasal cavity of the patient, remain
sufficiently open, unconstricted and/or unobstructed during exhalation whereby
any CO2 and/or any other patient byproduct gases transferred to alveoli, from
the
blood stream of the patient, is able to flow along this normal gas exhaust
airway
passages and be exhaled by the patient during an exhalation breath.
[094] Due to the higher delivery rates of the present invention, e.g., 26 to
60 liters
per minute, for example, the respiratory therapy system 40 is prone to
generate
noise as the respiratory gas is supplied along the main respiratory gas supply
line 16, the auxiliary gas supply lines 14, the supply arms 26 and/or the
heads 72
to the patient. It is desirable to design the respiratory therapy system 40 to
minimize generation of noise, during operation of the respiratory therapy
system 40, to a noise level of less than 50 decibels or so and more preferably
to
reduce the generation of noise, during operation of the system, to a noise
level
approaching about 46 decibels or so. In order to achieve such a reduction in
noise, it is important that the main respiratory gas supply line 16, the
auxiliary
respiratory gas supply lines 14, the supply arms 26 and the head 72 all have
gradually bends, transitions, expansions and contractions along the
respiratorygas
flow path. That is, all of the respiratory gas supply lines, conduits, tubes,
duct,
channels, components, etc., must avoid any sharp, acute or right angle bends,
turns or curvatures and also avoid any rapid expansion and contraction of the
gas
supply lines, conduits, tubes, duct, channels, components, etc.
CA 02534750 2006-01-26
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[095] The reduction in noise is particularly important as the nasal cannula
12,
according to the present invention, is typically utilized at night while the
patient is
sleeping. To further reduce the noise, the transition from the supply arm 26
to the
tubular extension 30 can have a gradual increase in dimension so that there is
more gradual expansion of the respiratory gas that enters into the tubular
extension 30 and this will further assist with reducing the noise associated
with the
respiratory gas conveyed to the patient.
[096] To further assist with providing comfort to a patient utilizing the
respiratory
therapy system 40, a 360 degree rotatable swivel 80 (see Fig. 11) may be
provided, along the main respiratory gas supply line 16, for example, to
facilitate
rotation of the nasal cannula assembly 10 relative to a remainder of the
respiratory
therapy system 40. A preferred location for the swivel 80 is at a location
closely
adjacent the connection of the main respiratory gas supply line 16 with the
connector 18 which, in turn, is coupled to the pair of auxiliary respiratory
gas
supply lines 14. A first end portion 82 of a stationary housing 84 of the
swivel 80
encases or is received within the opening in the remote end of the main
respiratory
gas supply line 16. Preferably, the first end portion 82 of the stationary
housing 84
is glued, welded, or otherwise fixedly secured or attached to the main
respiratory
gas supply line 16 to prevent inadvertent removal or disconnection therefrom.
[097] The rotatable swivel 80 further includes a rotatable housing 90 which is
has
a first end 85 which is received by and encases the second end portion 86 of
the
stationary housing 84. A second end portion 89 of the rotatable housing 90
either
encases or is directly received within an opening of the connector 18.
Alternatively, a short supplemental section of the main respiratory gas supply
line 16 (not shown) may interconnect the swivel 80 with the connector 18.
An intermediate region of the rotatable housing 90, between the first and
second
end portions thereof, includes a small bend 88 of about 10 to about 45
degrees,
preferably about 20 degrees or so.
[098] The first end 85 of the rotatable housing 90 and the second end portion
86
of the stationary housing 84 each have a cooperating or mating components
which
retain the rotatable housing 90 in permanent engagement with the second end
CA 02534750 2006-01-26
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portion 86, e.g., by mating bearing surfaces or some other conventional
arrangement, while still allowing relative rotation between those two
components.
The first end 85 of the rotatable housing 90 includes an integral shoulder 92
while
the second end portion 86 of the stationary housing 84 includes an integral
shroud 94 with a cooperating shoulder 96. A fluid tight gasket or seal 98 is
sandwiched between the two shoulders 92, 96 to provide a seal which prevents
any treating respiratory gas from leaking thereby. The shroud 94 encloses the
gasket or seal 98 to minimize any damage thereto by the external environment.
A snap locking ring 99 has a protrusion which engages with an annular recess
provided in the exterior surface of the shroud 94 to captively retain the
rotatable
housing 90 on the stationary housing 84 while still allowing relative rotation
between those two components.
[099] The pair of auxiliary respiratory gas supply lines 14 are connected to
an
opposite end of the connector 18 and the swive180 permits rotation of the
nasal
cannula, the pair of auxiliary respiratory gas supply lines 14, the connector
18 and
the rotatable housing 90 relative to the stationary housing 84, the main
respiratory
gas supply line 16 and a remainder of the respiratory therapy system 40. It is
to
be appreciated that a variety of modifications and changes may be made to the
swivel 80, as would be readily apparent to those skilled in this art, without
departing from the invention. Such modifications and changes are considered to
be within the spirit and scope of the present invention.
[100] With reference now to Fig. 12, a diagnostic tool 113 which is useful in
measuring the nasal cavity pressure, during both patient inhalation and
exhalation
and is particularly suited for use in a sleep lab, will now be described. The
diagnostic tool 113 generally comprises, for example, either a "large" or a
"small"
nasal cannula 12 discussed above with reference to Figs. 9-10B but with a
modification. The head 72 located at the ridge of each one of the ridges of
the
supply arms 26 supports a pressure sensing hollow tube or probe 114 which is
either permanently secured thereto, e.g., glued or otherwise fastened thereto,
or
adjustably secured thereto in order to facilitate adjustment of the exposed
length
of the pressure sensing hollow tube or probe 114 relative to the respiratory
gas
CA 02534750 2006-01-26
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discharge outlet 32. The pressure sensing hollow tube or probe 114 preferably
enters through a rear end wall of the head 72 and passes within and through
the
interior space of the head 72 along an undersurface of one of the ridges 78
and
two adjacent side surfaces 75 which converge at that ridge 78 (see Fig. 12A).
The pressure sensing hollow tube or probe 114 preferably exits through a front
end
wall of the head 72 and extends parallel to the longitudinal axis of the ridge
of the
supply arm 26 away from the respiratory gas discharge outlet 32 deeper into
the
nasal cavity of the patient during use than a remainder of the nasal cannula.
The
exposed length of the pressure sensing hollow tube or probe 114, relative to
the
respiratory gas discharge outlet 32, typically ranges between 0.280 of an inch
(0.71 cm) and 0.670 of an inch (1.70 cm), regardless of whether or not the
pressure sensing hollow tube or probe 114 is permanently fixed to or
adjustable
relative to the head 72, and more preferably the exposed length of the
pressure
sensing hollow tube or probe 114, relative to the respiratory gas discharge
outlet 32, is about 0.52 of an inch (1.32 cm). Due to such spacing or
positioning
of the pressure sensing probe 114, each one of the pressure sensing probes 114
is suitably located at desired position within the nasal cavity to more
reliably detect
a nasal cavity pressure reading. In the event that the position of the
pressure
sensing probe 114 relative to the respiratory gas discharge outlet 32 is
adjustable,
this tends to further facilitate more reliably detection of a pressure reading
within
the nasal cavity.
[101] The opposite end of each one of the pressure sensing probe 114 are both
coupled to supply a pressure reading to a single common pressure sensing
device 115 (see Fig. 12), such as a transducer manufactured by Korr Medical
Technologies, Inc. of Salt Lake City, Utah under the RSS 100 trademark/trade
name or a handheld transducer manufactured by of Braebon Medical Corporation
of Ogdensburg, New York. Alternatively, the opposite ends of each one of the
pressure sensing probe 114 may each be coupled to a separate pressure sensing
device 115 (see Fig. 12B) for measuring the pressure of each one of the
nostril
cavities of the patient. Preferably, the conduit or tubing, of the pressure
sensing
probe 114, has an outside diameter of between 0.068 of an inch (0.173 cm) and
CA 02534750 2006-01-26
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0.070 of an inch (0.178 cm) or so in order to minimize any disruption of the
respiratory gas flow through the interior space located within the head 72 of
the
nasal cannula assembly 10. As the pressure sensing probes 114 pass through the
head 72, it generally does not disrupt or alter the normal achieved leakage
interface between the exterior surface of the enlarged head 72 and the
inwardly
facing skin tissue 69 of the patient's nostril 71.
[102] The diagnostic tool 113 is particularly adapted to be utilized to
titrate and
determine a desired back pressure within the breathing passages of the patient
so
that the breathing passages remain sufficiently open during both inhalation
and
exhalation. It is to be appreciated that the leakage passages 81, formed by
each
pair of adjacent side surfaces 75, diverging from a common elongate valley 76,
and the inwardly facing skin tissue of the nostril 71, will typically vary
from patient
to patient, e.g., the leakage passages 81 for some patients will be largeror
smaller
than the leakage passages 81 of other patients. Further the breathing
passageways, the bronchi, the trachea, the lungs, the lung capacity, etc., for
each
patient also vary widely.
[103] During titration of a patient, typically the patient is permitted to
sleep and is
monitored with the diagnostic tool 113 while a respiratory gas is supplied to
a
patient at a first flow rate. The pressure within the nasal cavity of the
patient is
then determined by the pressure sensing probe 114 at this first respiratory
gas flow
rate. Depending upon the determined pressure and the detected breathing
characteristics of the patient, the technician will then adjust the flow rate
from the
respiratory gas source 23 to vary, e.g., either increase or decrease, the flow
rate
of the respiratory gas being supplied to the patient. For each stepped
increase or
decrease of the respiratory gas flow rate, the technician continues to monitor
the
pressure generated within the nasal cavities of the patient and the breathing
characteristics of the patient until the technician determines an optimum
respiratory gas flow rate that achieves a desired back pressure within the
breathing
passages of the patient so that the patient breathes adequately, especially
while
the patient is sleeping.
CA 02534750 2006-01-26
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[104] Following the use of the diagnostic tool 113, the patient will then have
a
reasonably good indication of the pressure within the breathing passages of
the
patient which is required in order for the patient to breath adequately, e.g.,
treat
sleep apnea. Once the patient is evaluated with the diagnostic tool 113, the
patient can then be supplied with or obtain a supply of similarly sized
cannulas for
use by the patient. The patient can then install one of these similarly sized
cannulas on his/her respiratory therapy system 40 and adjust the respiratory
gas
flow rate to this previously determined flow rate so that the patient wilt
generate or
create, within his/her breathing passageways and lungs, a sufficient back
pressure
and thereby facilitate a more complete exhalation or exhaustion of any CO2
and/or
any other patient byproduct gases which are contained in the lungs and removed
from the blood stream. It is to be appreciated that the diagnostic tool 113 is
not
limited solely to CPAP applications but may be utilized for a wide variety of
breathing and/or diagnostic applications.
[105] If desired, the respiratory therapy system 40 may be equipped with a
clock 100 (only diagrammatically shown in Figs. 13 and 13A) to display the
current
time to a patient using the respiratory therapy system 40. If desired, the
clock may
be equipped with an alarm to wake the patient at a desired wake up time in
order
to terminate supply or treatment of the respiratory gas after a desired
treatment
period. In addition, a water holding tank or reservoir 102 of the respiratory
therapy
system 40, for facilitate adding humidity to the respiratory gas prior to
delivery of
the same to the patient, may be equipped with a low water sensor 104 coupled
to
an indicator (not shown in the drawings) to provide either an auditory and/or
a
visual indication to the patient that the water level within the reservoir 102
is low
and requires replenishment. The reservoir 102 may also be equipped with a high
water sensor 108 coupled to an indicator (not shown in the drawings) to
provide
either an auditory and/or a visual indication to the patient that the water
level in the
reservoir is in excess of the amount of water required for efficient operation
of the
respiratory therapy system 40 and the patient should remove some water for
more
efficient operation of the respiratory therapy system 40. Lastly, the
reservoir 102
may be equipped with a conventional water heater (not shown ) to facilitate
heating
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of the water contained therein. However, one problem associated with heating
the
water in the reservoir 102 is the generation of calcium carbonate which has a
tendency to plate out on the inner surface of the reservoir 102. This may also
lead
to possible calcium carbonate plating of the water heater thereby requiring
periodic
servicing of the water heater. As each of the above features are conventional
and
well known in the art, a further detail description concerning the same is not
provided.
[106] To further insulate the heated and humidified respiratory gas from the
ambient environment, the main respiratory gas supply line 16 and/or the
auxiliary
respiratory gas supply lines 14 may be covered by or encased within a plastic
or
corrugated tube or some conventional insulating wrap or material 112, e.g., a
10
mm corrugated tube 112. Figs. 14 and 14A diagrammatically show the main
respiratory gas supply line 16 surrounded by or encased within the insulating
wrap
or material 112. An insulating air pocket 111 is formed between the exterior
surface of the main respiratory gas supply line 16 and the inwardly facing
surface
of the insulating wrap or material 112. The insulating wrap or material 112
helps
to insulate the respiratory gas from the external environment of the
respiratory
therapy system 40 and help maintains the temperature of the respiratory gas
substantially at the initially heated and supplied temperature and also
minimizes
the possibility of any humidity, added to the respiratory gas, condensing
along the
inner surface of either the main respiratory gas supply line 16, the connector
18,
the swivel 80, the pair of auxiliary respiratory gas supply lines 14 and/or
the nasal
cannula.
[107] As seen in Fig. 15, a slip loop or line tightening member 20 encases
both
of the auxiliary respiratory gas supply lines 14 to assist with applying
sufficient
tension to the auxiliary respiratory gas supply lines 14 to maintain the heads
72 of
the supply arms 26 adequately positioned within the nostrils 71 of the
patient.
Preferably the line tightening member 20 will have flared or enlarged mouth
120
and 122, at both opposed ends thereof, but will have a smaller dimensioned
intermediate section 124 for frictionally engaging with the exterior surface
of both
of the auxiliary respiratory gas supply lines 14. The intermediate section 124
is
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sized to have a sufficient interference fit with the exterior surface of the
auxiliary
respiratory gas supply lines 14 so as to be retained along the auxiliary
respiratory
gas supply lines 14 in any adjusted position. The frictional interference
connection, between the intermediate section 124 of the line tightening member
20
and the exterior surface of the auxiliary respiratory gas supply lines 14,
wili maintain the line tightening member 20 at its adjusted position while the
flared
mouths 120, 122 allow the auxiliary respiratory gas supply lines 14 to extend
away
from the line tightening member 20 and move freely relative thereto without
causing any sharp bend, kink or some other obstruction or constriction in
either of
the auxiliary respiratory gas supply lines 14.
[108] An important aspect of the present invention relates to providing a
constant
flow of a respiratory gas to a patient while also controlling the amount of
leakage
escaping between the inwardly facing skin 69 of the nostril 71 of the patient
and
the exterior surface of the head 72 of each of the supply arms. This
arrangement
results in the breathing passageways of the patient being sufficiently
inflated during
the entire breathing process so that the passageways do not tend to constrict,
collapse or otherwise obstruct relatively free breathing inhalation or
exhalation of
the patient.
[109] Typically, the total combined length of the auxiliary supplied lines 14
and the
main respiratory gas supply line 16, once connected with one another, extends
for
a combined length of between 3 feet and 50 feet or so, and more preferably
have
a total combined length of about 7 feet.
[110] The supplied respiratory gas provides the necessary resistance to the
patient, upon attempting an exhalation breath so that the breathing passageway
and lungs remain sufficiently inflated and thus do not have a tendency to
collapse,
constrict or otherwise close or inhibit relatively free breathing during
exhalation of
the patient.
[111] Due to the relatively high flow of the respiratory gas, the respiratory
gas
tends to dry out the nasal cavities and breathing passages of the patient. As
noted
above, in order to combat this, the respiratory gas is sufficiently humidified
to a
level approaching saturation while still avoiding condensation of the added
CA 02534750 2006-01-26
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moisture along the main respiratory gas line 16, the auxiliary respiratory gas
supply
lines 14, the swivel 80 and/or the connector 18.
[112] In a preferred form of the invention, a temperature thermistor (not
shown)
may be located adjacent the connection of the main respiratory gas supply line
16
to the pair auxiliary respiratory gas supply lines 14, at or adjacent the
connector 18, to determine the temperature of the respiratory gas just prior
to the
respiratory gas being split into two flow paths and conveyed to the nasal
cannula
assembly 10. This facilitates more accurate control of the temperature of the
respiratory gas being delivered to the patient.
[113] To further assist with controlling the temperature and/or humidity of
the
respiratory gas being delivered to the patient, the system 40 may be equipped
with
a conventional look-up table which has the relative humidities for different
temperatures stored therein, i.e., it will be appreciated that the respiratory
gas,
depending upon its temperature, will have different relative humidities.
The respiratory therapy system 40 can then utilize this stored temperature
and/or
humidity information to further optimize control of the humidity and
temperature of
the supplied respiratory gas during operation of the system. As such look-up
tables and utilization thereof are conventional and well known in the art, a
further
detailed description concerning the same is not provided.
[114] To facilitate adding moisture to the respiratory gas, the respiratory
gas is
passed through a passover humidifier 116 (see Fig. 13B) where the
respiratorygas
passes around a serpentine or maze-like flow path 117 from an inlet 118 to an
outlet 119 thereof around a plurality of the baffles 121 and an inwardly
facing
surface of an outer wall enclosing the passover humidifier 116. The
respiratory
gas, as it passes by, over and/or through the passover humidifier 116, is
sufficiently humidified to a desired humidity. However, one problem associated
with using tap water is the generation of calcium carbonate and/or other
compounds which tend to plate out on and along the surface of the baffles 121
and/or the inner surface of the reservoir and could also lead to possible
plating of
calcium carbonate and/or other compounds thereon. If desired, as discussed
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above, the reservoir can be equipped with both high and low water level alarms
to
notify the patient when service in the reservoir is required.
[115] The compressor supplies the respiratory gas to the reservoir where the
respiratory gas will receive a sufficient quantity of moisture and is then
passed to
the post heater where the moisturized respiratory gas is then heated to a
desired temperature, e.g., between 27 C and 32 C. Thereafter, the heated and
moisturized respiratory gas is then conveyed to the patient, via the auxiliary
respiratory gas supply lines 14, where the heated and moisturized respiratory
gas
is then inhaled by the patient. The temperature of the post heater is
controlled by
a controller 56 which controls the temperature of the post heater so that the
respiratory gas is heated to a desired temperature. If necessary, the
controller can
turn off the post heater entirely or shut it down if it becomes too hot due to
the
generation of excessive heat and then sound an alarm to notify the patient or
other
personnel that servicing of the post heater is required. The respiratory gas,
after passing through the post heater, typically will have a relative humidity
of
between 70 and 95 percent while it is preferable for the respiratory gas to
have a
relative humidity of up to 85 percent.
[116] With respect to heating of the respiratory gas, a post heating
arrangement
is preferred as it heats up and cools down relatively quickly thereby
facilitating
more accurate control of the temperature of the respiratory gas being supplied
to
the patient.
[117] If desired, the respiratory therapy system may also include a
respiratory
gas metering device (not shown) which facilitates conservation of use of the
respiratory gas during operation of the respiratory gas system. That is, the
respiratory gas metering device will interrupt the constant flow of the
respiratory
gas to the patient for a brief period of time, e.g., between breath when the
patient is neither inhaling or exhaling, in order to conserve use of the
respiratory
gas. As such respiratory gas metering device, for interrupting a constant flow
of
the respiratory gas to the patient for a brief period of time, is conventional
and
well known in the art, a further detail discussion conceming the same is not
provided.
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[118] Since certain changes may be made in the above described respiratory
therapy system without departing from the spirit and scope of the invention
herein involved, it is intended that all of the subject matter of the above
description or shown in the accompanying drawings shall be interpreted merely
as examples illustrating the inventive concept herein and shall not be
construed
as limiting the invention.
