Airway adapter with liquid containment pathway

Abstract

A gasway adapter providing a measurement chamber for gas measurement by a mainstream gas analyzer includes a body having a first end and a second end and configured to be connected into a ventilation circuit that delivers ventilation gas to and from a patient. The body forms a primary path including the measurement chamber and configured to allow ventilation gas to pass between the first end and the second end, and at least one auxiliary path separate from the primary path and located on an outer periphery of the primary path. The at least one auxiliary path is configured to contain liquid away from the measurement chamber.

Description

Background Technology

[0001] This disclosure relates generally to a respiratory gas sensor system for measuring one or more respiratory gas components in a patient's breathing circuit, and more specifically to a respiratory sensor system having a gas analyzer including a color detection system for component identification.

[0002] In anesthesia and intensive care, patient condition is typically monitored by analyzing the concentrations of inhaled and exhaled gases. This is done by feeding a small sample of the inhaled gas to a gas analyzer, or by connecting the analyzer directly to the breathing circuit. In nondispersive infrared (NDIR) gas analyzers, measurements are based on the absorption of infrared (IR) radiation in the gas sample. A radiation source directs an infrared beam through a measurement chamber to a radiation detector, whose output signal depends on the intensity of the absorbed radiation in the sample gas.

[0003] Radiation sources typically consist of an electrically heated filament or surface area and radiation-collecting optics, emitting radiation within a spectral range. A gas sample to be analyzed is conveyed through a measurement chamber. For example, the measurement chamber can be a tubular space with an inlet and outlet for the sample gas and a window that is transparent at the measurement IR wavelength and allows the IR wavelength to transmit through the chamber. As the gas sample passes through the measurement chamber, radiation is absorbed by the gas sample, and the amount of measurement IR wavelength transmitted through the chamber (i.e., from one window to another) indicates the amount of a specific gas component in the gas sample.

[0004] Radiation detectors generate electrical signals that depend on the radiation power falling on their sensitive region. The type of detector in a gas analyzer depends on its measurement wavelength. For measurements over a wide spectral range, thermal detectors are convenient because their sensitivity depends only on the efficiency of radiation conversion to heat. To make the detector's output signal sensitive to a specific gas component, the wavelength band of radiation arriving at the detector is selected such that the gas component absorbs the radiation within it. This selection is made using an optical bandpass filter; for example, the bandwidth of this optical bandpass filter could be 1% to 2% of the center wavelength.

[0005] Gas analyzers can be configured to measure different gas components. The absorption of a gas sample is measured at a wavelength band selected to match the absorption spectrum of the gas component of interest. Measurements of more than one gas component can be achieved using a single radiation detector and by continuously varying an optical bandpass filter along the optical path. Several radiation detectors can also be used in combination with corresponding bandpass filters. Different respiratory gases have relatively wide absorption wavelength ranges. Carbon dioxide and nitrous oxide can be measured between 3900 nm and 4600 nm, while anesthetics absorb in the 8000 nm to 10,000 nm region. Summary of the Invention

[0006] This summary is provided to introduce a series of concepts that will be further described in the detailed embodiments below. This summary is not intended to identify key or essential features of the claimed subject matter, nor is it intended to help limit the scope of the claimed subject matter.

[0007] In one embodiment, an airway adapter providing a measuring chamber for gas measurement via a mainstream gas analyzer includes a body having a first end and a second end and configured to connect to a ventilation circuit that delivers ventilation gas to and from a patient. The body forms a main path and at least one auxiliary path. The main path includes the measuring chamber and is configured to allow ventilation gas to pass between the first and second ends. The at least one auxiliary path is separate from the main path and located on its outer periphery. The at least one auxiliary path is configured to contain liquid remote from the measuring chamber.

[0008] One embodiment of a neonatal airway adapter, providing a measuring chamber for gas measurement within a neonatal ventilation circuit via a mainstream gas analyzer, has a body having a first end and a second end and configured to connect to a neonatal ventilation circuit that delivers ventilation gas to and from a neonatal patient. The body forms a main path and at least one auxiliary path, the main path including the measuring chamber and configured to allow ventilation gas to pass between the first and second ends, the at least one auxiliary path being located on the outer periphery of the main path. The at least one auxiliary path is separated from the main path and configured such that the flow rate through the auxiliary path is less than the flow rate through the main path. For example, the volume of the auxiliary path may not exceed 20% of the volume of the main path. The at least one auxiliary path is configured to contain liquid remote from the measuring chamber.

[0009] Various other features, objects, and advantages of the invention will become apparent from the following description taken in conjunction with the accompanying drawings. Attached Figure Description

[0010] This disclosure is described with reference to the following figures.

[0011] Figure 1 A mainstream gas analyzer is shown connected to an airway adapter in a ventilation circuit for ventilating a patient.

[0012] Figure 2 The airway adapter and mainstream gas analyzer are shown.

[0013] Figure 3A and Figure 3B An exemplary neonatal airway adapter according to an embodiment of the present disclosure is shown.

[0014] Figure 4A and Figure 4B Another embodiment of the airway adapter according to this disclosure is shown.

[0015] Figure 5A and Figure 5B Another embodiment of the airway adapter according to this disclosure is shown. Detailed Implementation

[0016] The inventors have recognized that a problem with existing airway adapters or absorption cells used to facilitate gas measurements via mainstream gas analyzers is the accumulation of liquid and vapor inside the measurement chamber of the airway adapter. Liquid buildup on the window of the airway adapter, through which the gas analyzer takes measurements, prevents the analyzer from performing accurate measurements. This is particularly problematic for neonatal airway adapters, where the connection path and measurement chamber volume are smaller than in adult airway adapters to reduce dead space in the neonatal ventilation circuit. In neonatal airway adapters, the optical window size is typically the same as that used in adult absorption cells, and therefore the window occupies a relatively large portion on the measurement chamber side, resulting in rapid liquid accumulation within the measurement chamber and significantly impacting the performance of gas measurements performed via the gas analyzer. The problem of liquid accumulation is especially prevalent in neonatal gas measurement applications due to the smaller volume and proportionally larger window size. A greater proportion of liquid accumulates in the neonatal ventilation circuit than in adult airway adapters, tending to impact the neonatal airway adapter window, and liquid in the measurement path (such as the infrared transmission path) attenuates radiation and prevents accurate gas measurements.

[0017] In response to the aforementioned problems and challenges in the relevant art, the inventors have developed the airway adapter disclosed in this invention, which has a separate path for accumulating liquid, configured to contain accumulating liquid remotely from the main path. The airway adapter disclosed in this invention has a main path that includes a measuring chamber and is configured to allow ventilation gas to pass through the airway adapter end-to-end. The airway adapter includes at least one auxiliary path separate from the main path, wherein the at least one auxiliary path is configured to contain liquid remotely from the main path to separate as much accumulating liquid as possible from the measuring chamber and, in particular, the optical window. Thus, one or more auxiliary paths are positioned such that most or as much liquid flow is through the auxiliary path, or otherwise contained in the auxiliary path remotely from the measuring chamber.

[0018] In various embodiments, the auxiliary path may extend the full length of the airway adapter between the first and second ends, or may be configured such that the auxiliary path extends only a portion of the length of the airway adapter. At least one auxiliary path is positioned along the outer periphery of the main path. For example, at least one auxiliary path may be located on the lower half or bottom side of the body below the main path, where liquid has a greater tendency to accumulate due to gravity. In one embodiment, the auxiliary path may be centered below the main path on the bottom side of the body. In another embodiment, multiple auxiliary paths may be distributed on the lower half of the outer periphery of the main path.

[0019] The system can be configured such that the airway adapter is positioned at an angle (e.g., away from the patient), wherein the end of the airway adapter on the patient side is higher than the end of the airway adapter on the ventilator side. In such embodiments, the system can be configured such that fluid is directed out of the second end (ventilator end) of the airway adapter away from the patient. Alternatively, in embodiments where the airway adapter is in a horizontal position, fluid can accumulate and remain in the second path and remain there. If the fluid accumulation volume is significant, it may completely fill and block the auxiliary path, and may even accumulate above the auxiliary path inlet and in the main path. However, a considerable portion of the fluid remains in the auxiliary path away from the main path, and especially in the auxiliary path away from the measurement chamber.

[0020] Auxiliary pathways or groups of auxiliary pathways can be configured such that they do not significantly affect the dead space created by the airway adapter. This is particularly important in neonatal applications, where minimizing dead space is crucial given the small lung size and respiratory volume of newborns. Therefore, at least one auxiliary pathway can be configured to limit the flow rate through it to minimize dead space while still allowing fluid to accumulate in the auxiliary pathway. The total flow rate through at least one auxiliary pathway can be configured such that it is 50% or less of the flow rate through the primary pathway. In other embodiments, the flow rate through one or more auxiliary pathways does not exceed 40% of the flow rate through the primary pathway. In still other embodiments, the total flow rate through the auxiliary pathways does not exceed 20% of the flow rate through the primary pathway. In still other embodiments, the total flow rate through at least one auxiliary pathway does not exceed 10% of the flow rate through the primary pathway.

[0021] To reduce the flow velocity through the auxiliary path and thus decrease the dead space created by it, the auxiliary path may have a narrowing segment comprising a portion of the auxiliary path's length, the cross-sectional area of ​​which is smaller than that of other segments of the auxiliary path. For example, the narrowing segment may be located in the central portion of the airway adapter's body, such that it is approximately centered along the length of the auxiliary path. In a particular example, the narrowing segment of the auxiliary path may be aligned with and below a window. In other embodiments, the narrowing segment may be located at other locations along the auxiliary path closer to one end.

[0022] Exemplary embodiments of the airway adapter disclosed in this invention and a system including the airway adapter disclosed in this invention are described in... Figures 1 to 5B The present invention is illustrated and discussed in various ways herein. The respiratory gas sensor system 100 disclosed herein includes an airway adapter 8 or absorption pool with an auxiliary path configured to contain liquid that has accumulated in a region of the ventilation circuit, away from the main path, where a gas analyzer 7 is taking measurements. The airway adapter 8 has a body 17 with a top side 21 and a bottom side 22. The system 100 is generally configured such that the bottom side 22 is below the top side 21, such that gravity forces the liquid downward toward the bottom side 22. The body 17 has a first end 18 and a second end 19, each end configured to attach to a corresponding element within the ventilation circuit. In the depicted example, the first end 18 on the patient side of the body 17 is configured to connect to an endotracheal tube 3, and the second end 19 is configured to connect to a vital capacity measuring adapter 11 and / or to a Y-shaped element 4 that allows gas to circulate in and out of the ventilator 2.

[0023] The gas analyzer 7 can be removably connected to the airway adapter 8, such as via clamps on the airway adapter 8 configured to form friction connections thereto. The top side 21 can be configured to connect to the gas analyzer 7. In the depicted example, the adapter body 17 includes two opposing clamps 24. Figure 3B , Figure 4B and Figure 5B The two opposing clamps are configured to be removably connected to the airway adapter, which is positioned above the top side 21 of the central portion 28 of the airway adapter 8 and extends above the side of the central portion 28 to allow gas measurement through the window 14.

[0024] like Figure 1The illustration shows a ventilation circuit with a medical gas analyzer. Patient 1 is connected to ventilator 2 via endotracheal tube 3, Y-shaped fitting 4, inspiratory branch 5, and expiratory branch 6. Gas analyzer 7 is connected to airway adapter 8, which in turn connects to the endotracheal tube fitting. Gas analyzer 7 is a mainstream gas analyzer that measures the gas flowing between ventilator 2 and patient 1 without requiring gas samples to be drawn into a separate gas analyzer.

[0025] Figure 1 The analyzer shown is electrically connected to the patient monitor 10 via cable 9. The gaseous component being measured can be carbon dioxide (CO2), nitrous oxide (N2O), or any volatile anesthetic, such as halothane, enflurane, isoflurane, desflurane, and sevoflurane. Additionally, a spirometry adapter 11 may be present for measuring gas flow in the breathing circuit. In this example, sensor 12 is located at the distal ends of both pressure-dependent tubes 13. The spirometry sensor can be as follows: Figure 1 It can be connected separately or integrated into a mainstream gas analyzer.

[0026] exist Figure 2 The diagram shows different views of the gas analyzer 7 to better illustrate the components within the gas analyzer and the construction of the adapter 8, which can be a disposable or reusable adapter. It is provided with at least one optical window 14 to allow the absorption of IR radiation by the gas components in the measurement chamber between the optical windows. Typically, two IR transmission optical windows 14 are present. An IR emitter 20 is located on one side of the adapter, and one or more detectors 30 are located on the opposite side, such that IR radiation from the emitter 20 is guided through the windows 14 and reaches the detectors 30.

[0027] The signal or radiation measurement data from each detector 30 are amplified and modified to determine the concentration of the respiratory gas component to be measured. As described above, the respiratory gas component to be measured can be any IR-absorbing component, such as carbon dioxide, nitrous oxide, or various volatile anesthetics. All these gases absorb IR radiation in some specific wavelength region, and this region (i.e., the measurement wavelength) is selected, for example, using a narrowband filter, and provided to the detector 30.

[0028] Figures 3A to 5B Exemplary airway adapters 108, 108' and 208 are shown, illustrating embodiments and features of the airway adapters with auxiliary pathways disclosed in this invention. Figure 3A and Figure 3B A first exemplary newborn adapter 108 is shown, and Figure 4A and Figure 4B A second exemplary newborn adapter 108' is shown. Figures 5A to 5BAn exemplary airway adapter 208 constructed for use in adult applications is shown.

[0029] Figure 3A A vertical cross-sectional view through the central portion of the airway adapter is shown, and Figure 3B A cross-sectional view along the length of a neonatal airway adapter 108 is shown. The neonatal airway adapter 108 includes a body 117, such as one formed of molded plastic. The body 117 has a first end 118, a second end 119, and additional measuring segments or other elements, such as the first end being configured to connect to an endotracheal tube 3 or other patient interface, the second end being configured to connect to a Y-shaped member 4, and the additional measuring segments or other elements forming a neonatal ventilation circuit. The body 117 forms a patient terminal portion 127 extending from the first end 118 to a central portion 128, and a ventilator terminal portion 129 between the central portion and the second end 119. A measuring chamber is located in the central portion 128, which has two windows 114 positioned on opposite sides of the measuring chamber and configured to allow gas measurement via a mainstream gas analyzer 7. The gas analyzer 7 is adapted above the top side 121 of the central portion 128 and performs gas measurement through the windows 114. Figure 1 and Figure 2 The arrangement shown is similar, with the airway adapter 108 configured to be received on the top side 121 via clamp 124 and connected to the gas analyzer 7.

[0030] The neonatal airway adapter 108 provides a primary path 140 that includes a measuring chamber in a central segment 128 configured to allow ventilation gas to pass through the measuring chamber between a first end 118 and a second end 119 of the airway adapter body 108. The primary path 140 of the neonatal adapter 108 has a smaller volume than the primary path used in an adult airway adapter, and the primary path is configured to restrict flow through auxiliary paths to reduce increased dead space in the neonatal ventilation circuit. For example, considering the smaller lung capacity of neonates compared to adults, the primary path 140 in the neonatal embodiment may be narrower than the primary path in the adult embodiment, resulting in a smaller volume and flow rate in the primary path of the neonatal airway adapter.

[0031] The auxiliary path 150 is positioned below the main path 140 towards the bottom side 122 of the body 117. In the depicted example, only one auxiliary path is provided. In other embodiments, two or more auxiliary paths may be included, such as arranged around the outer perimeter of the main path 140. For example, two or more auxiliary paths may be arranged around the main path 140, such as arranged around the lower half of the perimeter of the main path 140 and below the window 114.

[0032] The auxiliary path 150 is configured to limit the flow rate compared to the primary path 140. For example, the peak flow rate through the primary path 140 in the neonatal adapter 108 can be tens of milliliters per second (mL / s), which is a common flow rate for neonatal airway adapters. In such examples, the total flow rate through the auxiliary path 150 is less than 50% of the primary path flow rate. In certain examples, the flow rate through the auxiliary path 150 may not exceed 40%. In yet another example, the auxiliary path flow rate may be even more limited, such as not exceeding 30%, 20%, or even 10% of the primary path flow rate. As stated above, reducing the flow rate through the auxiliary path 150 is necessary to reduce the dead space created by the neonatal airway adapter 108, and therefore a significant narrowing of the auxiliary path may be necessary, depending on the neonatal application area, such as the size and developmental stage of the newborn. Only the volume of the portion of the auxiliary path through which gas passes is counted as part of the dead space volume. The volume of the non-ventilated portion of the auxiliary path (i.e., not having a flow path through adapter 108) is not considered part of the dead space. Therefore, when the flow velocity through the auxiliary path is smaller due to the constraints in the auxiliary path, the amount of increase in dead space is also smaller.

[0033] In cases involving two or more auxiliary paths, the neonatal airway adapter 108 can be configured such that the total flow rate through the auxiliary paths does not exceed the threshold relative flow rate through the primary path. This can be any of the aforementioned examples applicable to a particular neonatal application and constraints on dead space.

[0034] Additionally, one or more auxiliary paths 150 may be configured such that liquid accumulates and thereby reduces the available dead space. That is, the liquid accumulated in the auxiliary path 150 reduces the volume occupied by gas (including the patient's exhaled gas) and thus reduces the dead space during use.

[0035] The depicted auxiliary path 150 includes a narrowing segment 152. The narrowing segment 152 extends at least a portion of the length of the auxiliary path 150 and is configured to restrict the flow velocity through it. In the depicted example, the narrowing segment 152 is located in the central portion 128 and centered along the auxiliary path 150 below the window 114. The cross-sectional area of ​​the narrowing segment 152 is smaller than the portion of the auxiliary path 150 not within the narrowing segment. The cross-sectional area of ​​the narrowing segment can be uniform or can be a tapered shape with a gradually changing cross-sectional area; for example, the diameter MD of the auxiliary path 150 gradually decreases and / or increases along its length BL.

[0036] exist Figure 3BIn the example shown, the narrowing segment 152 comprises three sub-segments, including two tapered sub-segments. The narrowing segment 152 has a first tapered sub-segment of length TL1 and a second tapered sub-segment of length TL2 on either side of the narrowing intermediate sub-segment of length NL. The narrowing segment NL is formed by a flange 154 extending upward from the bottom wall or side of the auxiliary path 150 and provides a consistent, further narrowed cross-sectional area at the center of the length of the auxiliary path 150 below the window 114.

[0037] In various embodiments, flange 154 may have a length NL forming a narrowed intermediate segment that is at least as long as the diameter WD of window 114. In some embodiments, the length NL may be 1.5 times the window diameter WD. For example, if the window diameter WD is 4 mm, the length NL may be 6 mm. In such embodiments, the diameter MD of the narrowed intermediate segment NL may be 2 mm. Limitations may be set based on the desired flow relationship between the primary and secondary paths.

[0038] The flange 154 forming the narrowing intermediate sub-segment NL can extend from the bottom side of the auxiliary path, the top side of the auxiliary path, or from around the perimeter, such as when the cross-sectional area of ​​the narrowing intermediate sub-segment NL is circular. Figure 3A As shown in the image.

[0039] The cross-sectional areas of each of the tapered segments TL1 and TL2 gradually decrease towards the center until the flange 154. In the depicted example, the flange 154 and the tapered edges of the tapered segments TL1 and TL2 extend from the bottom side of the auxiliary path 150. However, in other embodiments, the flange and tapered edges extend downward from the top side of the auxiliary path 150, such as from the bottom of the partition wall 149. In yet another example, the narrowing segment may be formed by protrusions on both the top and bottom sides and / or around the entire perimeter of the auxiliary path 150. For example, the cross-section of the narrowing segment 152 across its length may be circular.

[0040] In one implementation, the cross-sectional area can be uniformly reduced so that there is no flange 154, and instead the conical segments TL1 and TL2 extend all the way to the center. For example, the smallest cross-sectional area may be below window 114 at approximately the center of the length BL of the neonatal airway adapter 108.

[0041] In other embodiments, the tapering can be removed, and the flange 154 can extend the full length of the narrowing segment 152, which can be longer or shorter than the central segment 128.

[0042] In the depicted example, the narrowing segment 152 substantially extends the length of the central portion 128 of the airway adapter 108. The narrowing segment 152 is centered below the window 114. In other embodiments, the narrowing segment 152 may extend only a portion of the central portion 128, such as the portion centered below the window 114. For example, the narrowing segment 152 may be at least as long as the window diameter WD, and in some embodiments may be at least 1.5 times the window diameter WD.

[0043] In other embodiments, the narrowing segment 152 may be longer than the central portion 128, such as extending into one or both of the patient distal portion 27 and the ventilator distal portion 129. For example, the conical segments TL1 and TL2 may further extend outward toward the ends 118 and 119. In some embodiments, the conical segments TL1 and TL2 may extend all the way to the ends 118 and 119. In such embodiments, the cross-section of the assist path 150 across its length may be circular, and the cross-section of the circle may gradually decrease toward the center between the ends 118 and 119.

[0044] exist Figure 3A and Figure 3B In the neonatal airway adapter 108 shown, the auxiliary path 150 extends along the entire length BL of the airway adapter 108 between the first end 118 and the second end 119. The auxiliary path 150 is isolated and separated from the main path 140 by a partition wall 149. In the depicted example, the partition wall 149 extends the length BL between the first end 118 and the second end 119. However, in other embodiments, the partition wall 149 may extend only a portion of the length BL. For certain applications, and especially for neonatal applications, it is desirable that the partition wall 149 extends at least the length of the central portion 128, and in some applications extends beyond the central portion 128 and into each of the patient terminal portion 127 and the ventilator terminal portion 129. For example, the partition wall 149 separating the auxiliary path 150 from the main path 140 may be at least 75% of the length BL of the airway adapter 108. In other embodiments, the partition wall 149 may be at least 90% of the length BL of the airway adapter 108.

[0045] Figure 4A and Figure 4B Another exemplary neonatal airway adapter 108' is shown. Figure 4A This is an end view of adapter 108', showing a first end 148 configured to connect to a patient interface (such as endotracheal tube 3). Figure 4BThis is a perspective view of a longitudinal sectional view of adapter 108'. In the depicted embodiment, the auxiliary path has a cylindrical narrowing segment 152' extending the length of a central portion 128. The narrowing segment 152' has a consistent cross-sectional area, except for additional narrowing sub-segments formed by flange 154'. The isolation wall 149' separating the main path 150' from the auxiliary path 149' has a curved notch 148 at a first end, which is configured to guide fluid leaving the patient's airway into the auxiliary path 150' and away from the main path 149'.

[0046] Figure 5A and Figure 5B An exemplary airway adapter 208 is shown, such as one that can be used for ventilation measurements in adult patients. Figure 5A A vertical sectional view of the airway adapter 208 is shown, and Figure 5B A longitudinal sectional view of the airway adapter 208 is shown. In this example, the isolation wall 249 extends only a portion of the length BL' of the airway adapter 208. Therefore, the assist path 250 extends only a portion of the length BL' of the airway adapter 208. In the depicted example, the isolation wall 249 generally extends the length of the central portion 228 and substantially does not extend into the patient terminal portion 227 or the ventilator terminal portion 229.

[0047] Compared to the neonatal airway adapter 108, the adult airway adapter 208 has a larger main path 240. The main path 240 is defined by a body 217 and extends between a first end 218 and a second end 219 of the airway adapter 208. The airway adapter 208 includes a central portion 228 that provides a measurement chamber and is configured to receive a gas analyzer 7, and a clamp 224 included on the top side 221 of the body 217. The gas analyzer 7 is fitted above the top side 221 of the central portion 228 and performs measurements through a window 214, as described above. An auxiliary path 250 is located on the bottom side 222 of the airway adapter 208 below the main path 240.

[0048] The auxiliary path 250 includes only a portion of the length BL' of the airway adapter 208, which in this example extends across the central portion 228 housing the measurement chamber. Similarly, the isolation wall 249 extends only a portion of the length BL' and passes through the central portion 228. Thus, the isolation wall 249 forms the auxiliary path 250 to contain fluid remote from the measurement chamber in the central portion 228, and particularly from the window 228. In other embodiments, the isolation wall 249 may further extend along the length BL', such as extending the auxiliary path 250 partially or entirely across the length of each of the patient terminal portion 27 and the ventilator terminal portion 29.

[0049] This written description uses examples to disclose the invention, including the best mode, and also enables those skilled in the art to perform and use the invention. Certain terms are used for the purpose of brevity, clarity, and ease of understanding. Unnecessary limitations should not be inferred from this description beyond the requirements of the prior art, as such terms are used for descriptive purposes only and are intended to be understood broadly. The patent scope of this invention is defined by the claims and may include other examples that would occur to those skilled in the art. These other examples are intended to be within the scope of the claims if they have features or structural elements that are not different from the literal language of the claims, or if they include equivalent features or structural elements that are not substantially different from the literal language of the claims.

Claims

1. A gas passage adapter, the gas passage adapter providing a measurement chamber for gas measurement via a mainstream gas analyzer, the gas passage adapter comprising: A body having a first end and a second end and configured to be connected to a ventilation circuit that delivers ventilation gas into and out of the patient; The main path includes the measuring chamber and is configured to allow the ventilation gas to pass between the first end and the second end; At least one auxiliary path, the at least one auxiliary path being separate from the main path and located on the outer periphery of the main path; and The at least one auxiliary path is configured to contain liquid remote from the measuring chamber. The at least one of the auxiliary paths has a narrowing segment that includes a portion of the length of the auxiliary path and is configured to limit the flow velocity.

2. The airway adapter according to claim 1, wherein, The at least one auxiliary path is on the bottom side of the body below the main path.

3. The airway adapter according to claim 1, wherein, The at least one auxiliary path is separated from the main path along at least the length of the central portion of the main body.

4. The airway adapter according to claim 1, wherein, The at least one auxiliary path extends in parallel to the main path.

5. The airway adapter according to claim 1, wherein, The narrowing segment is located in the central portion of the main body.

6. The airway adapter according to claim 5, wherein, The narrowing segment is configured to limit the flow velocity through the at least one auxiliary path such that the flow velocity does not exceed 50% of the flow velocity through the main path.

7. The airway adapter according to claim 6, wherein, The flow rate through the at least one auxiliary path does not exceed 40% of the flow rate through the main path.

8. The airway adapter according to claim 7, wherein, The flow rate through the at least one auxiliary path does not exceed 20% of the flow rate through the main path.

9. The airway adapter according to claim 1, wherein the airway adapter further comprises at least two auxiliary paths, wherein, The total flow rate through the at least two auxiliary paths does not exceed 20% of the flow rate through the main path.

10. The airway adapter of claim 1, wherein the airway adapter is a neonatal adapter, and wherein, The volume of the main pathway does not exceed 2.5 mL.

11. The airway adapter according to claim 10, wherein, The at least one auxiliary path has a narrowing segment that includes a portion of the length of the auxiliary path and is configured to limit the flow velocity through the at least one auxiliary path to no more than 40% of the flow velocity through the main path.

12. A neonatal airway adapter, the neonatal airway adapter providing a measuring chamber for gas measurement within a neonatal ventilation circuit via a mainstream gas analyzer, the airway adapter comprising: A main body having a first end and a second end and configured to be connected to the neonatal ventilation circuit, the neonatal ventilation circuit delivering ventilation gas into and out of the neonatal patient; The main path includes the measuring chamber and is configured to allow the ventilation gas to pass between the first end and the second end; At least one auxiliary path, the at least one auxiliary path being separate from the main path and located on the outer periphery of the main path, wherein the auxiliary path is configured such that the flow velocity through the auxiliary path is less than the flow velocity through the main path; and The at least one auxiliary path is configured to contain liquid remote from the measuring chamber. The at least one of the auxiliary paths has a narrowing segment that includes a portion of the length of the auxiliary path and is configured to limit the flow rate.

13. The neonatal airway adapter according to claim 12, wherein, The at least one auxiliary path connects the first end and the second end, and is separated along the length of at least the central portion of the body.

14. The neonatal airway adapter according to claim 12, wherein, The at least one auxiliary path extends parallel to the main path between the first end and the second end.

15. The neonatal airway adapter according to claim 12, wherein, The at least one auxiliary path is on the bottom side of the body below the main path.

16. The neonatal airway adapter according to claim 12, wherein, The narrowing segment is located in the central portion of the main body.

17. The neonatal airway adapter according to claim 12, wherein the neonatal airway adapter further comprises at least two auxiliary pathways.

18. The neonatal airway adapter according to claim 17, wherein, The total flow rate through the at least two auxiliary paths does not exceed 40% of the flow rate through the main path.

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