Device for detecting carbon dioxide in working gas

Abstract

An apparatus (1) comprises a tubular body (2) within which a working gas is delivered, the tubular body extending along an associated longitudinal axis (A) and defining a passage (3) for passage of the working gas; at least one detection unit (5) associated with the tubular body (2), the detection unit (5) communicating with the channel (3) and comprising two detection elements (6) opposite each other to define a detection axis (R) and adapted to allow the passage of an optical signal generated by an external measuring device for detecting carbon dioxide in the working gas, the detection unit (5) defines a chamber (7) in fluid-operated communication with the channel (3) for the passage of a portion of the working gas; wherein the detection unit (5) protrudes from the tubular body (2) in a direction transverse to the longitudinal axis (A), the chamber (7) being offset with respect to the channel (3).

Description

Technical Field

[0001] The invention relates to a device for detecting carbon dioxide in a working gas, in particular in the medical field. Background Art

[0002] One possible medical application of a device of this type is in an extracorporeal blood circulation circuit.

[0003] In fact, it is known that in special cardiac operations it is necessary to establish an extracorporeal blood circulation, the main purpose of which is to perfuse the vital organs, that is, to supply them with oxygenated blood to ensure their normal functioning.

[0004] In particular, systems of known type are provided with an oxygenation device in which blood drawn from the patient's venous line is enriched with oxygen before being delivered to the patient's arterial line.

[0005] Suitably, the oxygenation device comprises an inlet channel and an outlet channel for a working gas for supplying oxygen to the blood and / or removing carbon dioxide from the blood.

[0006] Therefore, the amount of carbon dioxide removed by the oxygenation device is a crucial parameter for monitoring the progress of extracorporeal circulation and assessing the proper oxygenation of the blood.

[0007] For this purpose, i.e. to detect the amount of carbon dioxide removed from the transfused blood of the patient, a measuring device is usually used, which is called a "capnometer" in professional terminology, and is connected to the oxygenation device in a fluid-operated manner via a suitable connecting line, the task of which is to convey the working gas from the oxygenation device to the inlet of the measuring device.

[0008] Capnometers are also used to measure the amount of carbon dioxide in the air a patient exhales, such as during mechanical ventilation therapy or anesthesia. Such devices can determine in real time whether a patient is breathing normally.

[0009] In particular, in certain clinical situations, where part of the carbon dioxide is removed by the patient and part by an oxygenator placed along the extracorporeal circuit, it is crucial to determine the contribution of each of them, i.e. to quantify the amount of carbon dioxide removed by the patient and the oxygenator.

[0010] The carbon dioxide measuring meter utilizes a special detection device which comprises a tubular body of the "cuvette" type in which the working gas is transmitted and through which a light signal transmitter passes and a receiver located opposite the transmitter receives the light signal.

[0011] In this way, by analyzing the optical signal received by the receiver, for example by absorption spectrophotometry of the optical signal, the amount of carbon dioxide contained in the working gas can be tracked.

[0012] Specifically, the tubular body extends along an associated longitudinal axis and defines a passage for the flow of a working gas.

[0013] The known detection device further comprises a detection unit comprising two detection elements for allowing the passage of light signals and arranged along the longitudinal axis of the tubular body.

[0014] These detection elements are arranged at positions on the side surface of the tubular body so that the optical signal passes through the passage of the working fluid in a direction transverse to the longitudinal axis of the working fluid.

[0015] This way, as the gas flows through, the light signal passes through the gas itself and the amount of carbon dioxide in the gas can be measured.

[0016] However, known detection devices do have some disadvantages.

[0017] In fact, there is also a high concentration of water vapor in the working gas, which tends to condense on the inner wall of the detection device, causing the condensed water vapor to accumulate and flow on the inner wall of the tubular body. When this happens to the detection element, the measurement will be distorted, so a correction factor must be applied to obtain a true detection result. Summary of the invention

[0018] The main object of the present invention is to design a device for detecting carbon dioxide in a working gas which can accurately detect the carbon dioxide even when there is accumulation and flow of condensed water vapor on the wall of the tubular body.

[0019] Another object of the invention is to devise a device for detecting carbon dioxide in a gas which is not altered by the possible presence of water vapor on the wall of the tubular body, thus avoiding the use of a correction factor for the detection result.

[0020] Another object of the present invention is to design a device for detecting carbon dioxide in a working gas which can overcome the above-mentioned shortcomings of the prior art in a simple, reasonable, easy-to-use, effective and cheap manner.

[0021] This object is achieved by a device for detecting carbon dioxide in a working gas having the features of claim 1 . BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Other features and advantages of the invention will become more apparent from the description of a preferred but non-exclusive embodiment of a device for detecting carbon dioxide in a working gas, which is illustrated by way of schematic but non-limiting example in the accompanying drawings, in which:

[0023] Figure 1 is an axonometric diagram of a detection device according to a first embodiment of the present invention;

[0024] Figure 2 yes Figure 1 A longitudinal sectional view of the device;

[0025] Figure 3 yes Figure 1 A transverse cross-sectional view of the device;

[0026] Figure 4 is an axonometric diagram of a detection device according to a second embodiment of the present invention;

[0027] Figure 5 yes Figure 4 A longitudinal sectional view of the device;

[0028] Figure 6 yes Figure 4 A transverse cross-sectional view of the device. DETAILED DESCRIPTION

[0029] With particular reference to the drawings, reference numeral 1 denotes throughout an apparatus for detecting carbon dioxide in a working gas.

[0030] In the context of the present disclosure, the term "working gas" refers to, for example, air or oxygen, which escapes from an extracorporeal blood oxygenation device of a type known to a person skilled in the art. As is known, a blood oxygenation device comprises an inlet for the blood to be oxygenated, an outlet for the oxygenated blood, an inlet channel for the working gas (for example air or oxygen) and an outlet channel for supplying oxygen to the blood and / or removing carbon dioxide from the blood. More specifically, the device 1 can be connected to an outlet channel of the blood oxygenation device and / or to the breathing circuit of a patient in order to monitor the contribution of the removal of carbon dioxide from the native lungs.

[0031] The device 1 comprises a tubular body 2 in which a working gas is conveyed. The tubular body 2 extends along a relative longitudinal axis A and defines a channel 3 for the passage of the working gas. The plurality of axial ends of the tubular body 2 can be connected to an outlet channel of a blood oxygenation device or to a breathing circuit of a patient. Depending on whether the tubular body 2 is connected to an outlet channel of a blood oxygenation device or to a breathing circuit of a patient, the plurality of axial ends of the tubular body 2 or at least one of the plurality of axial ends are configured differently.

[0032] The tubular body 2 is made of a polymeric plastic material.

[0033] The tubular body 2 comprises two mounting ends 4 for connecting to outlet channels of a blood oxygenation device.

[0034] The device 1 further comprises at least one detection unit 5 connected to the tubular body 2, the detection unit 5 being in communication with the channel 3. The detection unit 5 is located in the middle between the two mounting ends 4.

[0035] The detection unit 5 includes two detection elements 6 , which are opposite to each other to define a detection axis R and allow an optical signal generated by an external measuring device to pass therethrough to detect carbon dioxide in the working gas.

[0036] The detection unit 5 is suitable for operating in combination with a measuring device of the absorption spectrophotometric type, which is configured to emit a light signal and obtain a signal after absorption by the working gas. The measuring device comprises a transmitter and a receiver of the infrared photodiode type, for example, and defines a seat suitable for receiving the detection unit 5.

[0037] The detection element 6 is made of a different material from the detection unit 5. Specifically, the detection element 6 is made of a material that is translucent to infrared radiation. For example, the detection element 6 is made of sapphire glass.

[0038] On the other hand, the detection unit 5 is made of a polymeric plastic material. The polymeric plastic material and the material of the tubular body 2 may be of the same type or of a different type, such as a rubber type.

[0039] Therefore, the device 1 is capable of detecting carbon dioxide during the process of the working gas passing through the tubular body 2 .

[0040] According to the invention, the detection unit 5 protrudes from the tubular body 2 in a direction transverse to the longitudinal axis A. Thus, the detection unit 5 extends transversely to the longitudinal axis A.

[0041] More specifically, the detection unit 5 protrudes from the tubular body 2 in a direction perpendicular to the longitudinal axis A. The detection unit 5 extends orthogonally with respect to the longitudinal axis A and protrudes outward from the tubular body 2 .

[0042] The detection unit 5 thus defines a chamber 7 in fluid-operating communication with the channel 3 and offset therefrom in such a manner that the chamber 7 is not interrupted by the longitudinal axis A of the channel 3. In fact, the chamber 7 is misaligned relative to the channel 3.

[0043] Then, the detection unit 5 divides the working airflow into a main airflow flowing in the channel 3 and a secondary airflow flowing in the chamber 7 .

[0044] At the location of the detection unit 5 , the secondary air flow leaves the channel 3 and enters the chamber 7 , where it intercepts the optical signal, enables the measurement, and then enters the channel 3 again.

[0045] The offset position of the chamber 7 means that the detection unit 5 is not occupied by condensate. In fact, the condensate consists of water vapor droplets heavier than carbon dioxide and other exhaled gases, which are not deflected by the secondary airflow and are deposited on the wall of the tubular body 2.

[0046] The detection cell 5 is not intercepted by condensate passing through the channel 3, so the light signal passing through the detection cell itself is not affected by condensate interference, thereby allowing optimal carbon dioxide detection.

[0047] Advantageously, the detection axis R passes outside the channel 3. Therefore, the detection axis R does not pass through the channel 3, but only through the chamber 7. Therefore, the detection is performed on the gas present in the chamber 7, that is to say, the secondary flow is detected instead of the primary flow.

[0048] In particular, the detection axis R is substantially orthogonal to the longitudinal axis A. The detection is performed substantially perpendicularly to the flow direction of the working gas.

[0049] The detection elements 6 are opposite one another relative to a symmetry plane P passing through the longitudinal axis A.

[0050] according to Figures 1 to 3 In the first embodiment shown, the detection unit 5 is integrally formed with the tubular body 2. In this first embodiment, the detection element 6 is preferably co-molded with a single piece consisting of the tubular body 2 and the detection unit 5, as described in more detail below.

[0051] However, according to Figures 4 to 6 In the second embodiment shown, the detection unit 5 and the tubular body 2 are made separately. To this end, the device 1 comprises a fastener 8 located between the detection unit 5 and the tubular body 2.

[0052] Advantageously, the fastener 8 is an interlocking type device.

[0053] In this way, the detection unit 5 and the tubular body 2 can be assembled in a very cheap manner.

[0054] However, it cannot be excluded that the fasteners may be of a different type known to a person skilled in the art.

[0055] The device 1 according to the second embodiment further comprises a seal adapted to ensure a tight seal between the detection unit 5 and the tubular body 2 and between the detection element 6 and the detection unit 5. Suitably, the seal coincides with the fastener 8 if the detection unit 5 is made of an elastically deformable material.

[0056] The seal comprises, for example, a seal made of an elastically deformable material.

[0057] According to another aspect, the present invention also relates to a method for manufacturing the device 1 for detecting carbon dioxide in a working gas according to one or more of the above embodiments.

[0058] The method according to the present invention comprises the following steps:

[0059] providing a mold having a profile substantially complementary to the tubular body 2;

[0060] providing a shaped fixture having a contour at least partially complementary to the detection unit 5;

[0061] Plastic molding the tubular body 2 by a mold; and

[0062] The detection unit 5 is formed by the forming jig.

[0063] According to a first embodiment, the shaping phase is performed simultaneously with the moulding phase, so that the detection unit 5 can be defined as a single piece having a tubular body 2 .

[0064] Specifically, the forming stage of the detection unit 5 is completed by inserting a forming jig into the tubular body 2 during the relevant molding stage. In fact, the forming jig is an "external thread" tool that is inserted into a mold associated with the tubular body 2 to achieve the forming of the detection unit 5.

[0065] The forming stage forms a passage opening 9 in the tubular body 2 through which the forming jig is inserted and removed.

[0066] To this end, the method comprises a closing phase of the passage opening 9. In particular, the closing phase is carried out by using a plug element 10.

[0067] However, it cannot be excluded that the closing phase can be carried out in a different way, for example by plastic welding.

[0068] Advantageously, the forming jig is suitable for supporting the detection element 6 during the forming stage. In practice, the detection element 6 is mounted on the detection unit 5 and is combined with the detection unit 5 while forming the detection unit 5 during the forming stage.

[0069] On the other hand, according to the second embodiment, the forming stage of the detection unit 5 is performed separately from the molding stage. In this case, the detection unit 5 can be made of a material different from the tubular body 2, preferably made of an elastically deformable material.

[0070] Suitably, the shaping of the detection unit 5 also includes the definition of a housing seat for the detection element 6 , into which the detection element 6 is inserted after the shaping is completed, for example by taking advantage of the elastic deformation capabilities of the material from which the detection unit 5 is made.

[0071] Conveniently, the forming phase of the detection unit 5 comprises a step of defining the fasteners 8 on the detection unit itself. The forming jig essentially comprises parts formed in a complementary manner to the corresponding fasteners.

[0072] The method also comprises a stage of mounting the detection unit 5 on the tubular body 2 .

[0073] The installation phase comprises at least the step of coupling the detection unit 5 to the tubular body 2 by interlocking means.

[0074] Depending on the configuration of fastener 8, the mounting phase may also comprise a step of defining fasteners 8 on tubular body 2 complementary to those defined on detection unit 5. This definition step may be carried out simultaneously with the moulding phase, or separately, for example by machining.

[0075] Practice has shown that the described invention achieves the intended purpose, with particular emphasis on the fact that the device according to the invention for detecting carbon dioxide in a working gas is able to carry out an accurate detection even in the presence of condensed water vapor on the wall of the tubular body.

[0076] The presence of a detection unit protruding from the tubular body makes it possible to detect the carbon dioxide contained in the working gas without being influenced by condensate that may be present in the tubular body itself, thereby obtaining a reading that is as true as possible and without the need to use correction factors.

[0077] The device for detecting carbon dioxide according to the present invention can be applied to a breathing circuit of a patient or an outlet channel of a blood oxygenation device.

Claims

1. A device (1) for detecting carbon dioxide in a working gas, comprising: a tubular body (2) in which a working gas is conveyed, the tubular body extending along a relative longitudinal axis (A) and defining a passage (3) for the passage of the working gas; at least one detection unit (5) associated with the tubular body (2), the detection unit (5) communicating with the channel (3) and comprising two detection elements (6) opposite to each other to define a detection axis (R) and suitable for allowing the passage of an optical signal generated by an external measuring device for detecting carbon dioxide in the working gas, the detection unit (5) defining a chamber (7) communicating with the channel (3) in a fluid-operated manner for the passage of part of the working gas; It is characterized in that The detection unit (5) protrudes from the tubular body (2) in a direction transverse to the longitudinal axis (A), and the chamber (7) is offset relative to the channel (3).

2. The device (1) according to claim 1, characterized in that The detection unit (5) protrudes from the tubular body (2) in a direction perpendicular to the longitudinal axis (A).

3. Device (1) according to one or more of the preceding claims, characterized in that The detection axis (R) passes outside the channel (3).

4. Device (1) according to one or more of the preceding claims, characterized in that The detection axis (R) is substantially orthogonal to the longitudinal axis (A).

5. Device (1) according to one or more of the preceding claims, characterized in that The detection elements (6) are opposite to each other with respect to a symmetry plane (P) passing through the longitudinal axis (A).

6. Device (1) according to one or more of the preceding claims, characterized in that The detection unit (5) and the tubular body (2) are integrally formed.

7. Device (1) according to one or more of the preceding claims, characterized in that The detection unit (5) and the tubular body (2) are manufactured separately, and the device (1) comprises a fastener (8) located between the detection unit (5) and the tubular body (2).

8. Device (1) according to one or more of the preceding claims, characterized in that The fastener (8) is of the interlocking type.

9. Device (1) according to one or more of the preceding claims, characterized in that Also included is a seal associated with the fastener (8).

10. A method for manufacturing a device (1) for detecting carbon dioxide in a working gas according to one or more of the preceding claims, characterized in that The following steps are involved: providing a mould having a profile substantially complementary to the tubular body (2); Providing a forming fixture having a contour at least partially complementary to the detection unit (5); Plastic molding the tubular body (2) by means of the mold; and The detection unit (5) is formed by the forming fixture.

11. The method according to claim 9, characterized in that The shaping phase is carried out simultaneously with the molding phase, so that the detection unit (5) is defined as a single piece with the tubular body (2).

12. The method according to claim 9, characterized in that The forming jig is suitable for supporting the detection element (6) during the forming stage, and the detection element (6) is made of a different material from the detection unit (5).

13. The method according to claim 9, characterized in that The forming stage is performed separately from the molding stage, and the detection unit (5) is made of a different material from that of the tubular body (2).

14. The method according to claim 12, characterized in that The forming stage comprises the step of defining the fastener (8) on the detection unit (5).

15. The method according to claim 13, characterized in that The method comprises the step of installing the detection unit (5) to the tubular body (2), which step at least comprises the step of coupling the detection unit (5) to the tubular body (2) in an interlocking manner.

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