JP3677672B2 - Airway adapter - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an airway adapter that is attached to, for example, a ventilator and measures the concentration of carbon dioxide in respiratory air.
[0002]
[Prior art]
When artificially breathing a living body using a ventilator, an airway adapter is attached to the flow path to measure the concentration of carbon dioxide in the respiratory air. FIG. 4 is an external perspective view showing a configuration of an example of a conventional airway adapter. In FIG. 4, the axial center portion of the cylindrical flow tube 1 has a rectangular cross section, and circular windows 2 that transmit infrared rays are opened at opposite positions on both side walls of this portion. Is formed.
[0003]
As shown in the cross-sectional view of FIG. 5, a stepped portion 3 whose inside diameter is reduced is formed concentrically on the inner periphery of the window portion 2, and is formed in a disk shape with polyester or the like through the stepped portion 3. A transparent sheet 4 which is the formed transparent film is pasted to form a transmission window. An anti-fogging layer 5 is applied or deposited on the inner surface of the transparent sheet 4.
[0004]
FIG. 6 is a cross-sectional view corresponding to FIG. 5 showing the structure of another example of a conventional fixing method of the transparent sheet 4 to the window portion 2. In FIG. 6, the outer periphery of the transparent sheet 4 is fixed to the inner periphery of the window portion 2 by caulking or welding from the outside by the frame 6. At this time, the anti-fogging layer 5 on the inner surface of the transparent sheet 4 is substantially flush with the inner wall surface of the flow tube 1.
[0005]
[Problems to be solved by the invention]
However, according to the conventional example shown in FIG. 5, since there is a step between the inner wall of the flow tube 1 and the inner surface of the anti-fogging layer 5, the moisture contained in the respiratory air becomes water droplets, and the moisture 8 as shown in FIG. Accumulate in the direction of gravity of the step. For this reason, there is a possibility that the amount of light when infrared rays pass through the window portion 2 is reduced, resulting in a measurement error.
[0006]
Further, according to the conventional example shown in FIG. 6, since the inner wall of the flow tube 1 and the inner surface of the anti-fogging layer 5 are substantially the same surface, there is no possibility of water collecting on the inner periphery of the window portion 2, When the airway adapter is placed so that the water is horizontal and the water condensed on the flow pipe flows along the inner wall of the flow pipe 1, measurement error may occur because it passes over the anti-fogging layer 5 as shown in FIG. 8. was there.
[0007]
The present invention has been made in view of such a situation, and it is possible to reduce the influence of water in the breathing air flowing in the flow tube being measured, and to perform measurement stably for a long period of time. The purpose is to provide an adapter.
[0008]
[Means for Solving the Problems]
To achieve the above object, the present invention provides an airway adapter comprising: a flow tube through which a breathing gas passes; and a transmission window that is formed at a position facing a side wall of the flow tube and transmits infrared light. A frame protruding from the inner peripheral surface of the flow tube and surrounding the transmission window is provided .
[0009]
According to the above configuration, when water droplets due to moisture in the respiratory air flowing in the flow tube flow along the inner wall of the flow tube, the water droplets pass outside the frame protruding from the inner peripheral surface of the flow tube and pass over the transmission window. Never pass. As a result, the infrared light transmitted through the transmission window is not affected by water droplets, and no measurement error occurs.
[0011]
It said transmission window, if Ru is provided on the end face projecting into the flow tube of the frame, water droplets will not pass through the upper transmission window.
[0012]
Further, if the frame is formed up to a non-squeezed space in the flow tube, a flow path is formed from the front of the space to be squeezed, so that it is further avoided that water drops pass through the transmission window. be able to.
[0013]
Moreover, if the narrowing part of the said flow tube is provided with a taper, it can prevent that a water droplet collides and scatters near the entrance of the space to be narrowed.
[0014]
Further, if the anti-fogging layer is formed on the inner surface of the transmission window, the transmission window can be prevented from being fogged.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a configuration example of an embodiment of an airway adapter of the present invention used for measuring carbon dioxide concentration will be described with reference to the drawings. FIG. 1 is a cross-sectional view taken along an axis showing an example of the configuration of an embodiment of the present invention, and FIG. 2 is a cross-sectional view taken along line AA showing the mounting structure of the transparent sheet 4 of FIG. In these drawings, portions corresponding to those of the conventional example shown in FIGS. 4, 5, and 6 are denoted by the same reference numerals, and the description thereof is omitted as appropriate.
[0016]
In FIGS. 1 and 2, the frame 6 is formed in a hexagonal shape, and the window portion 2 is in a state where the flange portion is in contact with the stepped portion 3 of the window portion 2 formed at a position opposite to the side wall of the flow tube 1. Is fitted and airtightly fixed. Further, the inner portion of the frame 6 protrudes inward from the inner peripheral surface of the flow tube 1. A transparent sheet 4 having an antifogging layer 5 formed on the surface is fixed to an end surface of the frame 6 protruding into the flow tube 1 to form a transmission window. Reference numeral 7 denotes an attachment portion for fixing a unit in which an infrared light emitting portion and a light receiving portion (not shown) are integrated to the flow tube 1.
[0017]
According to the present embodiment, when the airway adapter is attached to the flow path of the ventilator, water droplets due to moisture in the respiratory air flowing through the flow tube 1 move along the inner wall of the flow tube 1. At this time, the moisture passes through the outside of the frame 6 provided to protrude from the inner surface of the flow tube 1 as a flow path of water as shown in FIG. 3, so that water droplets are stretched over the inner surface of the frame 6. It does not pass over the anti-fogging layer 5 of the sheet 4. As a result, the infrared light transmitted through the transparent sheet 4 is not affected by water droplets, and measurement error of the concentration of carbon dioxide in the respiratory air does not occur.
[0018]
As shown in FIG. 9, the frame 6 may be formed up to a space that is not squeezed in the flow tube 1. Here, the frame 6 is composed of a main body portion 6a and a pair of end portions 6b, and has a hexagonal shape as a whole. The main body 6a has a configuration similar to that of the frame 6 of the above embodiment, although the outer shape is slightly different. The main body 6a is fitted into the window 2 in a state where the flange portion is in contact with the stepped portion 3 of the window 2, and is airtight. It is fixed (see FIG. 2). The pair of end portions 6b are respectively formed integrally with the flow tube 1 inside the flow tube 1, and the respective leading ends reach a space that is not squeezed. Thereby, before a water droplet approachs into the window part 2, a flow path is divided by the flame | frame 6, and it can avoid further that it passes a transparent film | membrane. As shown in FIG. 9, in this example, the narrowed portion 9, that is, the entrance / exit portion of the narrowed space, is provided with a taper at the inner corner of the flow tube 1. This reduces the amount of water droplets colliding with the squeezed portion 9 and scattering it, and further avoids the water droplets from passing through the transparent film.
[0019]
In the above embodiment, the case where the frame 6 is formed in a hexagonal shape has been described. However, the shape of the frame 6 is not limited to the hexagonal shape, and the flow resistance of respiratory air flowing in the flow tube 1 can be reduced. Any other shape may be used. Further, even if the transmission window is formed using sapphire, the same effect can be obtained by the frame.
[0020]
【The invention's effect】
As described above, according to the airway adapter of the present invention , water droplets due to moisture in the breathing air flowing in the flow tube pass outside the frame. As a result, the infrared light transmitted through the transmission window is not affected by water droplets, measurement errors such as gas concentration do not occur, and stable measurement can be performed for a long time.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view along an axis showing a configuration example of an embodiment of an airway adapter for gas concentration measurement according to the present invention.
FIG. 2 is a cross-sectional view taken along line AA in FIG.
3 is an explanatory view showing the flow of moisture flowing in the flow tube of FIG. 1. FIG.
FIG. 4 is an external perspective view showing a configuration of an example of a conventional airway adapter for gas concentration measurement.
FIG. 5 is a sectional view showing a first example of a conventional structure for attaching a transparent sheet to a flow tube.
FIG. 6 is a sectional view showing a second example of a conventional structure for attaching a transparent sheet to a flow tube.
FIG. 7 is an explanatory diagram showing a water droplet retention state in the case of the first example shown in FIG. 6;
FIG. 8 is an explanatory diagram showing the flow of water drops in the case of the second example shown in FIG.
FIG. 9 is a partially cutaway perspective view showing the configuration of another embodiment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Flow pipe 2 Window part 4 Transparent sheet (transparent film) 5 Anti-fog layer 6 Frame

Claims (5)

A flow tube through which breathing gas passes;
A transmission window that is formed at opposite positions on the side wall of the flow tube and transmits infrared light;
In an airway adapter comprising
An airway adapter comprising a frame protruding from an inner peripheral surface of the flow tube and surrounding the transmission window . The airway adapter according to claim 1, wherein the transmission window is provided on an end surface of the frame protruding into the flow tube . The flow tube has a squeezed portion, and the transmission window is formed on a side wall of the squeezed portion of the flow tube,
The airway adapter according to claim 1 or 2, wherein a tip of an end portion of the frame in the flow tube reaches a non-narrowed space inside the flow tube . The airway according to any one of claims 1 to 3, wherein a taper is provided at an inner corner of the flow tube at an entrance / exit portion of the narrowed space of the flow tube. adapter. The airway adapter according to any one of claims 1 to 4, wherein an antifogging layer is formed on a surface inside the flow tube of the transmission window .

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