Surgery – Respiratory method or device – Means for supplying respiratory gas under positive pressure
Reexamination Certificate
1999-06-21
2001-04-17
Lewis, Aaron J. (Department: 3761)
Surgery
Respiratory method or device
Means for supplying respiratory gas under positive pressure
C128S204230
Reexamination Certificate
active
06216692
ABSTRACT:
BACKGROUND OF INVENTION
1. Field of Invention
The present invention relates to an airway adaptor for measurement of the concentration of carbon dioxide gas. Such an airway adaptor is attached to a respirator in order to measure the concentration of carbon dioxide gas in a respiratory gas.
2. Related Art
When respiration of a patient is artificially performed by using a respirator, an airway adaptor is attached to a flow path of the respirator, so as to measure the concentration of carbon dioxide gas in a respiratory gas.
FIG. 4
is an external perspective view showing the configuration of an example of an airway adaptor of the prior art. Referring to
FIG. 4
, a center portion in the axial direction of a cylindrical flow tube
1
has a tubular shape having a rectangular section. Circular apertures
2
which allow infrared light to be transmitted therethrough are opened at opposed positions of side walls of the portion, respectively.
As shown in a section view of
FIG. 5
, a step portion
3
in which the inner side has a smaller diameter is concentrically formed in the inner periphery of each of the apertures
2
. A transparent window
4
serving as a transparent film which is made of polyester or the like and formed into a disk-like shape is applied to the window via the step portion
3
. An anti-fogging layer
5
is applied to or deposited on the inner face of the transparent window
4
.
FIG. 6
is a section view showing the configuration of another example of a prior art method of fixing the transparent window
4
to the aperture
2
, and corresponding to FIG.
5
. Referring to
FIG. 6
, the outer periphery of the transparent window
4
is fixed to or heat-found on the inner periphery of the aperture
2
by the frame
6
with caulking the frame from the outside. In this case, the anti-fogging layer
5
on the inner surface of the transparent sheet
4
is substantially flush with the inner wall face of the flow tube
1
.
In the prior art example shown in
FIG. 5
, the step is formed between inner wall of the flow tube
1
and the inner-surface of the anti-fogging layer
5
, and hence the moisture content in a respiratory gas is condensed into waterdrops thereon. As shown in
FIG. 7
, the condensed waterdrop
7
gathers in the gravitational direction of the step portion. Therefore, the amount of infrared light which is transmitted through the window
2
is reduced, thereby producing a measurement error.
In the prior art example shown in
FIG. 6
, since the inner wall of the flow tube
1
is substantially flush with the inner face of the anti-fogging layer
5
, there is no fear that water gathers around the inner periphery of the aperture
2
because there is no step portion as with the prior art example of
FIGS. 5 and 7
. When the airway adaptor is positioned such that transparent window
4
is arranged horizontally water condensed in a flow tube flows along the inner wall of the flow tube
1
, however, water passes over the anti-fogging layer
5
as shown in
FIG. 8
, and hence there arises a fear that a measurement error may occur.
SUMMARY OF INVENTION
The invention has been conducted in view of the foregoing circumstances. It is an object of the invention to provide an airway adaptor for measuring the concentration of carbon dioxide gas which prevents waterdrops in a flow tube from passing over an inner surface of the transparent window, on measurement, thereby allowing measurement to be stably performed for a long term.
In order to attain the object, the invention is an airway adaptor for measurement of a gas concentration comprising:
a flow tube through which a respiratory gas flows;
transparent windows formed at opposed positions of side walls of said flow tube, and allowing infrared light to be transmitted therethrough; and
a water path formed on said side wall to prevent a waterdrop from being passed over said transparent windows.
According to this configuration, when waterdrops due to the moisture content in a respiratory gas flowing through the flow tube flows along the inner wall of the flow tube, the waterdrops pass over the water path formed in the frame, which do not pass over the transparent films on windows. Therefore, the waterdrops are prevented from passing over the transparent films which stretch on the inner faces of the frames. As a result, infrared light transmitted through the transparent films is not interrupted by the waterdrops, and hence a measurement error does not occur.
The water path is formed by projecting the frame from the inner surface of the flow tube. The frame is sealingly fitted on an inner peripheral portion of the aperture and stretches the transparent sheets on the inner faces thereof. As a result, the waterdrop passes through the outer peripheral portion of the frame.
On the other hand, when the frame is formed beyond a narrowed portion of the flow tube, the flow path is formed in a space before the narrowed portion so that the device is more free from the phenomenon that waterdrops pass over the transparent sheets.
Further, when the taper portion is provided on the narrowed portion of the flow tube, waterdrop splashing by hitting against an entrance portion is avoided of the narrowed portion.
REFERENCES:
patent: 4177381 (1979-12-01), Mcclatchie et al.
patent: 4678488 (1987-07-01), Howard et al.
patent: 4886528 (1989-12-01), Aaltonen et al.
patent: 4914720 (1990-04-01), Knodle et al.
patent: 5067492 (1991-11-01), Yelderman et al.
patent: 5095900 (1992-03-01), Fertig et al.
patent: 5159934 (1992-11-01), Hoberman
patent: 5261415 (1993-11-01), Dussault
patent: 5282473 (1994-02-01), Braig et al.
patent: 5925831 (1999-07-01), Storsved
patent: 5932877 (1999-08-01), Braig et al.
patent: 5957127 (1999-09-01), Yamamori et al.
Dainobu Hidetoshi
Todokoro Noriaki
Yamamori Shinji
Lewis Aaron J.
Nihon Kohden Corporation
Sughrue Mion Zinn Macpeak & Seas, PLLC
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