U.S. patent application number 09/184111 was filed with the patent office on 2002-05-09 for nasal cannula.
Invention is credited to CHUA, JAMES, CURTI, JAMES N., SALTER, PETER W..
Application Number | 20020053346 09/184111 |
Document ID | / |
Family ID | 22675594 |
Filed Date | 2002-05-09 |
United States Patent
Application |
20020053346 |
Kind Code |
A1 |
CURTI, JAMES N. ; et
al. |
May 9, 2002 |
NASAL CANNULA
Abstract
This invention is a nasal cannula (10) having a septum (15)
therein, and two nares (13, 14) each having a hole (37, 35) therein
to help prevent occlusion of the device from secretions. The
cannula is connected to an oxygen source (G) and a CO2 monitor
(A).
Inventors: |
CURTI, JAMES N.;
(BAKERSFIELD, CA) ; CHUA, JAMES; (TEHACHAPI,
CA) ; SALTER, PETER W.; (TEHACHAPI, CA) |
Correspondence
Address: |
JERRY W BERKSTRESSER
SHOEMAKER & MATTARE
2001 JEFFERSON DAVIS HIGHWAY
SUITE 1203
ARLINGTON
VA
222020286
|
Family ID: |
22675594 |
Appl. No.: |
09/184111 |
Filed: |
November 2, 1998 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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09184111 |
Nov 2, 1998 |
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PCT/US98/05573 |
Apr 3, 1998 |
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Current U.S.
Class: |
128/207.18 |
Current CPC
Class: |
A61M 16/085 20140204;
Y10S 128/912 20130101; A61M 16/0666 20130101; A61M 2210/0625
20130101; A61M 2230/432 20130101 |
Class at
Publication: |
128/207.18 |
International
Class: |
A61M 016/06 |
Claims
What is claimed is:
1. An apparatus for insufflating a treating gas into the nose of a
patient and measuring carbon dioxide content in the exhalation of
the patient, said apparatus consisting of: an elongated hollow body
including a tubular portion adapted to be received on the skin
surface adjacent the nose; a wall within said hollow body defining
therein both an inhalation manifold and an exhalation manifold,
said wall providing a gas-tight seal positively preventing fluid
communication between said inhalation and exhalation manifolds;
supply means for connecting said inhalation manifold to a supply of
treating gas; a first hollow prong in fluid communication with said
inhalation manifold and adapted to be received in a first nasal
passage of the nose for insufflating said treating gas into the
nose; a second hollow prong in fluid communication with said
exhalation manifold and adapted to be received in a second nasal
passage of the nose for withdrawing a portion of the exhalation
therefrom, said prongs each being substantially smaller in diameter
than the respective nasal passages, so as not to occlude said
passages; and at least said second prong being provided with at
least one additional opening communicating with the hollow interior
of said second prong and said exhalation manifold; and means for
measuring the concentration of carbon monoxide in the exhaled gases
said means including means for withdrawing an exhaled gas sample
from said exhalation manifold.
2. A method for monitoring end tidal CO.sub.2 in unintubated,
conscious, spontaneously breathing patients who are receiving
administration of local and regional anesthesia or during recovery
from residual general anesthesia consisting of the steps of:
providing a nasal cannula on a patient, said cannula having an
elongated hollow body; a gas-tight partition in said hollow body to
divide said hollow body into a first zone and a second zone
separated from each other by said gas tight partition; gas supply
means including first conduit means communicating with said first
zone and a source of oxygen, second conduit means communicating
with said second zone and communicating with a means for detecting
and measuring the partial pressure of carbon dioxide in the exhaled
gases said elongated hollow body in addition containing separate
hollow nasal prongs each communicating with one of said first and
second zones and with respectively each nostril of the patient;
supplying oxygen to said patient from said source of oxygen through
said first conduit means to said first zone of said elongated
hollow body and into the patient's nostril through one of said
nasal prong means; withdrawing exhaled breath containing carbon
dioxide from said patient through the other of said nasal prongs
into said second zone of said elongated hollow body, through said
second conduit means and into said means for detecting and
measuring the partial pressure of carbon dioxide; and determining
the partial pressure of carbon dioxide at the end of the patient's
exhalation to obtain a clinical approximation of the papressure of
arterial carbon dioxide, wherein the other of said hollow nasal
prongs is provided with an opening in addition to the diameter of
the opening of said nasal prong and sized to prevent the
withdrawing of exhaled breath from causing occlusion of said hollow
nasal prong by adjacent tissue or patient secretions.
3. A nasal cannula comprising a face piece consisting of an
elongated hollow body terminating at both ends in tubular cross
section portions, two hollow nares communicating with the interior
of said hollow body protruding in parallel from positions adjacent
the center of the hollow body and spaced apart a sufficient
distance and each of sufficient length for the open terminus of
said nare to be received in or adjacent to the nostrils of a
patient, and a fluid tight wall located between the hollow nares
inside of the hollow body to prevent fluid communication between
the nares inside of the hollow body, at least one of said nares
being provided with at least one opening other than the opening
into the hollow body or the opposite terminus of said nare, said
opening being sized to prevent suction applied to said nare from a
carbon dioxide analyzer from drawing the open terminus of said nare
onto the adjacent tissue of the patient's nostril whereby the nare
would become occluded and located sufficiently near the terminus of
said nare to receive exhalation gases substantially undiluted by
atmospheric gases during sampling by a carbon dioxide analyzer.
4. A system for insufflating a treating gas into the nose of a
patient and for measuring the carbon dioxide concentration of the
patient's exhaled breath consisting of: a source of insufflating
gas; first conduit means connected to and in intermittent fluid
communication with said source of insufflating gas; cannula means
connected to said first conduit means and in fluid communication
with said source of insufflating gas and at least one nostril of a
patient; means for drawing a portion of the patient's exhaled gases
and measuring the concentration of carbon dioxide in the patient's
exhaled gases; second conduit means connected to and in fluid
communication with said drawing and measuring means, said second
conduit means being connected to said cannula means and in fluid
communication with at least one other nostril of a patient whereby
the gas delivery occurs only after the peak carbon dioxide
concentration is measured in each breath exhalation cycle; and
wherein said cannula means includes multiple fluid communication
means for means in communication with said drawing and measuring
means.
5. The system of claim 4 wherein the cannula means includes at
least two hollow nares each one of said two hollow nares only in
fluid communication with either said source of gas or said drawing
and measuring means.
Description
[0001] This application is a continuation of International
Application PCT/US98/05573, filed Apr. 3, 1998.
BACKGROUND OF THE INVENTION
[0002] The practice of measuring end-tidal carbon dioxide during
the administration of anesthesia, particularly regional anesthesia,
has grown markedly in the past several years. The reasons that
anesthesiologists have embraced this technique are described more
fully in U.S. Pat. No. 5,335,656 which is incorporated herein by
reference in its entirety.
[0003] The preferred nasal cannula used in this procedure is a
cannula which insufflates the patient with oxygen through one nare
of a cannula and separately samples the exhaled gases by drawing
the exhaled gas from the other nare into a conventional carbon
dioxide analyzer. The cannula is preferably provided with an
internal wall or system in the face piece to keep the conduits
separate for insufflation and sampling, however, separate lines can
be used or even multiple nares for insufflation and sampling,
though the latter device substantially increases the risk of gases
mixing which can distort the readings for end-tidal carbon dioxide.
It is preferred that two nares only are employed and that each nare
performs only one function, i.e., insufflation or sampling into or
from separate nostrils. Likewise, insufflation has normally been
continuous, however, it could advantageously be intermittent which
would further improve the end-tidal carbon dioxide measurement by
insuring that gases being sampled were representative of exhaled
gases undiluted by the other gases being insufflated. Most
preferably, the intermittent insufflation is accomplished by the
apparatus and method described in U.S. Pat. No. 5,626,131 which is
incorporated herein by reference in its entirety. Other so-called
demand insufflation devices which begin insufflation upon the start
of inhalation can also be employed.
[0004] Normal nasal cannulae are designed with the nares having a
slight inward curvature as they extend upward from the face piece.
This is anatomically desirable and important for imparting the
proper direction of insufflating gas into the nasal cavities. When
the patient is in the upright sitting position or ambulatory, this
is the most satisfactory design configuration. Conversely, problems
can be encountered if the patient is horizontal or prone and tends
to accumulate secretions in the nasal cavities. It can be a
particularly vexing problem if either the insufflation or sampling
nare becomes occluded during the use of the cannula for sampling
and monitoring end-tidal cidal carbon dioxide during the
administration of anesthesia.
OBJECTS OF THE INVENTION
[0005] It is therefore an object of the present invention to
provide a nasal cannula structure for sampling carbon dioxide which
reduces or eliminates the incidence of occlusion of the tip of the
carbon dioxide sampling nare during the removal of carbon dioxide
by the sampling line connected to a monitoring device and/or a
source of suction or vacuum.
[0006] It is also an object of the present invention to provide a
nasal cannula for insufflating a patient with oxygen while
accurately monitoring end-tidal carbon dioxide, that will continue
to function properly for its intended purpose when either or both
nares become occluded for any reason.
[0007] It is a further object to accomplish the foregoing objects
with a minimum risk of distorting the end-tidal carbon dioxide
readings from the sampled exhalation gases during the
administration of anesthesia.
BRIEF SUMMARY OF THE INVENTION
[0008] The foregoing objects and advantages are obtained by
providing a nasal cannula structure that is adapted for
insufflation and sampling, with additional holes or vents on the
nares of the nasal cannula, preferably both anterior and posterior
of one or both nares at a location proximate the entrance of the
nasal passageways when the cannula is in use.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] FIG. 1 is a frontal view of a normally positioned nasal
cannula on a patient (shown in phantom) connected to a gas source
(G) and a gas analyzer (A).
[0010] FIG. 2 is a rear view of the cannulae face piece shown in
FIG. 1.
[0011] FIG. 3 is a partial cross section of a nare of the nasal
cannula taken along the lines and arrows 3-3 of FIG. 2.
[0012] FIG. 4 is a plan view of the nasal cannula of FIG. 2.
DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENT
[0013] The nasal cannula 10 of one embodiment of the present
invention consists of a generally tubular face piece 12 having two
nares 13 and 14 and a septum 15 disposed in the center of the face
piece 12 between the openings 16 and 17, respectively, of the nares
13 and 14 (see FIGS. 2, 3 and 4). The openings 21 and 22 on the
ends of the face piece 12 are affixed to separate tubes 23 and 24
as shown in FIG. 1, which are separately connected to a source of
insufflating gas (G), such as oxygen, and a commercial carbon
dioxide monitoring unit (shown as A) which, in turn, has or is
connected to a vacuum pump or other means for drawing exhaled
breath containing carbon dioxide into an instrument that is capable
of measuring the concentration of the carbon dioxide in the sampled
gas.
[0014] During use of the cannula for both insufflation and the
monitoring of carbon dioxide concentration in the exhaled breath
(depicted schematically in FIG. 1), the readings for end-tidal
carbon dioxide can become distorted where there is undesirable
mixing with room air or with excess insufflating gas. Likewise,
carbon dioxide measuring devices which typically employ varying
amounts of suction or vacuum to obtain the gas sample to be
analyzed, can unduly dilute the sample or more seriously can draw
the tip 30 of the sampling nare (representatively shown in FIG. 3)
onto the adjacent surface of the tissue of the nasal passage and
occlude the opening 31 thereby restricting or even preventing
sampling of the exhaled gases for their carbon dioxide
concentration.
[0015] This is an especially serious problem where the patient is
prone and secretions can be present which are drawn into the
opening 31 at the tip 30 and which then either partially or totally
occlude the opening 31, during the administration of
anesthesia.
[0016] The anesthesiologist must respond by clearing the nare
opening after first removing the cannula from its location on the
face of the patient. This may be complicated where the patient is
draped in a manner which covers the cannula, such as in eye
surgery. It may also be difficult to detect the occlusion where the
end-tidal carbon dioxide measurement signal is only partially
degraded.
[0017] It has been discovered that the expedient of additionally
providing the nares with very small holes, shown collectively at 35
and 36 and 37 and 38, achieves the desired result of preventing an
undesirable and unnecessary level of suction at the opening 31 of
the tip 30 from developing sufficiently to draw the opening 31 into
the nasal tissue thereby occluding the opening. The holes are sized
large enough to prevent sufficient suction from developing at the
tip 30 to draw in mucosal secretions or attach the tip by suction
to the soft mucosal tissue, while still drawing an undiluted sample
of the exhaled gases to provide good end-tidal carbon dioxide
measurements. Likewise, too large an opening for these holes would
undesirably dilute the exhaled gas sample with room air or excess
insufflation gas.
[0018] Most preferably, as previously noted, the nasal cannula of
the present invention can be used in combination with an oxygen
delivery system that delivers the insufflating gas intermittently.
The delivery can be initiated at any time after the peak end-tidal
carbon dioxide measurement is achieved during exhalation and
continuing into the inhalation phase of the breathing cycle or
could be inhalation activated or designed to deliver only during
selected portions of all or only some of the inhalation phases of a
patient's breathing cycles. Preferably, the delivery should begin
before the termination of the exhalation phase, such as is
described in U.S. Pat. No. 5,626,131. Using intermittent delivery
substantially reduces the possibility of distorted carbon dioxide
readings due to gas mixing.
[0019] Likewise, slits or slots (not shown) may be employed in the
nares which could function in the same manner as the holes
described if they are positioned in such a manner to avoid collapse
or occlusion with the nasal tissues and provide the desired
function of preventing sufficient suction from developing at the
tip of the nare to cause it to be drawn, by suction, onto the
tissues. The holes provided as described herein are preferred as
there is less risk of occlusion and trauma from the edges of slits
or slots to the nasal tissue and potentially there is less risk of
gas dilution and mixing from occurring where the slits or slots are
overly large.
[0020] Further, the combination of intermittent insufflation using
the cannula of the present invention produces the desired end-tidal
carbon dioxide measurement, as described, and helps prevent patient
desaturation during the rigors of surgery and anesthesia
administration.
[0021] Preferably, the size of the openings is from between about
0.05 to about 0.07 inches though larger or smaller holes or single
holes may be advantageously employed in combination with specific
analytical apparatuses. The size and location of the openings can
vary with the analyzer selected and the proper function confirmed
without undue experimentation.
[0022] The invention described herein is to be limited only by the
scope of the appended claims and the applicable prior art.
* * * * *