Method and system for detecting concentration of nitric oxide

Abstract

The application provides a method and system for detecting concentration of nitric oxide, and relates to the technical field of medical treatment, wherein the method comprises the following steps: collecting exhaled gas sample in a breathing pipeline of a mechanical ventilation equipment; detecting characteristic time sequence information of carbon dioxide and time sequence characteristic information of nitric oxide in the exhaled gas sample; determining alveolar air section and / or airway gas section in the exhaled gas sample based on the characteristic time sequence information of carbon dioxide; determining section concentration information of nitric oxide in the exhaled gas sample according to the time sequence characteristic information of nitric oxide and the alveolar air section and / or the airway gas section; and determining alveolar air nitric oxide concentration and / or airway gas nitric oxide concentration of the exhaled gas sample according to the section concentration information of nitric oxide. The application can be suitable for continuous detection of alveolar air or airway gas nitric oxide concentration of patients with non-autonomous respiration.

Description

Technical Field

[0001] This application relates to the field of medical technology, and in particular to a method and system for detecting nitric oxide concentration. Background Technology

[0002] NO gas, as a signaling molecule, plays an important role in multiple systems of the human body. By detecting the concentration of NO in human exhaled air, the nature and degree of airway inflammation can be determined, assisting in the treatment of asthma and predicting the response to pulmonary hypertension. Therefore, the detection of exhaled NO concentration is of great significance for clinical diagnosis, disease development, and monitoring of treatment efficacy.

[0003] In recent years, many methods for detecting NO gas have been developed, including electrochemical methods, laser spectroscopy, and gas condensation methods. However, conventional methods all require conscious patients who can breathe independently to perform the tests. When measuring the concentration of exhaled NO, the patient needs to cooperate with the exhalation action and usually needs to control the exhalation flow rate.

[0004] The steps of the conventional method for detecting exhaled NO concentration are as follows: (1) Take a deep breath to exhale the air in your lungs; (2) Hold the inhalation filter in your hand, cover your mouth with the filter tip, and inhale deeply into your lungs; (3) After inhaling into your lungs, do not hold your breath. Exhale at a steady flow rate within the specified flow rate range for about 10 seconds. Do not leak air, change air, hold your breath, or spray saliva during the process. Otherwise, you will need to retest; (4) The detection device will display the exhaled NO concentration result after about 1-2 minutes.

[0005] For patients with non-voluntary breathing, such as those on mechanical ventilation devices like ventilators, the inability to control their breathing makes it difficult to cooperate with routine exhaled NO concentration testing. Therefore, how to measure alveolar NO concentration in these patients has remained an unresolved clinical problem. Furthermore, routine exhaled NO concentration testing cannot provide continuous monitoring, while mechanically ventilated patients often suffer from multiple critical illnesses and are prone to drastic changes in their condition within a short period. Continuous NO concentration monitoring can promptly detect changes in the patient's condition, buying time for subsequent treatment and providing continuous data support for determining the treatment plan. Summary of the Invention

[0006] The purpose of this application is to provide a method and system for detecting nitric oxide concentration, which can be adapted to the continuous detection of alveolar / airway nitric oxide concentration in patients with non-voluntary breathing.

[0007] In a first aspect, this application provides a method for detecting nitric oxide concentration, the method comprising: collecting an exhaled gas sample from the breathing tubing of a mechanical ventilation device; detecting characteristic temporal information of the exhaled gas sample and temporal characteristic information of nitric oxide; determining alveolar gas segments and / or airway gas segments in the exhaled gas sample based on the characteristic temporal information; determining segmental concentration information of nitric oxide in the exhaled gas sample based on the temporal characteristic information of nitric oxide and the alveolar gas segments and / or airway gas segments; and determining the alveolar nitric oxide concentration and / or airway nitric oxide concentration of the exhaled gas sample based on the segmental concentration information of nitric oxide.

[0008] Furthermore, the aforementioned time-series information includes one or more of the following: time-series carbon dioxide content information in exhaled gas sample, time-series exhaled gas flow rate information, time-series exhaled gas volume information, time-series exhaled gas pressure information, and time-series exhaled gas volume information.

[0009] Furthermore, when the aforementioned time-series characteristic information includes time-series content information, the step of determining the alveolar air segment and / or airway air segment in the exhaled gas sample based on the time-series characteristic information of carbon dioxide includes: generating a carbon dioxide content curve based on the time-series content information of carbon dioxide; wherein, the carbon dioxide content curve is used to characterize the correspondence between carbon dioxide content and time; detecting a first time period from the curve value starting at zero to the inflection point of the curve's rising phase, and a second time period from the inflection point of the curve's rising phase to the end of the curve's rising phase; determining the first time period as the airway air segment and the second time period as the alveolar air segment.

[0010] Further, the step of determining the segmental concentration information of nitric oxide in the exhaled gas sample based on the temporal characteristic information of nitric oxide and the alveolar gas segment and / or airway gas segment includes: generating a nitric oxide concentration curve based on the temporal characteristic information of nitric oxide; wherein the nitric oxide concentration curve is used to characterize the correspondence between nitric oxide concentration and time; detecting the target concentration curve segment corresponding to the alveolar gas segment from the nitric oxide concentration curve; and / or detecting the target concentration curve segment corresponding to the airway gas segment from the nitric oxide concentration curve; and determining the nitric oxide concentration information corresponding to the target concentration curve segment as the segmental concentration information of nitric oxide in the exhaled gas sample.

[0011] Furthermore, the step of determining the segmental concentration information of nitric oxide in the exhaled gas sample based on the temporal characteristic information of nitric oxide and the alveolar gas segment and / or airway gas segment further includes: performing temporal compensation on the alveolar gas segment and / or airway gas segment; temporal compensation includes shifting the segment time forward or backward; detecting the target concentration curve segment corresponding to the alveolar gas segment after time compensation from the nitric oxide concentration curve; and / or detecting the target concentration curve segment corresponding to the airway gas segment after time compensation from the nitric oxide concentration curve; and determining the nitric oxide concentration information corresponding to the target concentration curve segment as the segmental concentration information of nitric oxide in the exhaled gas sample.

[0012] Furthermore, the above-mentioned steps for time-series compensation of alveolar air segments and / or airway air segments include: calculating the time difference using a fixed time-series compensation value set before the equipment leaves the factory, or calculating the time difference using a preset algorithm during equipment operation, and shifting the time of alveolar air segments / airway air segments forward or backward based on the time-series compensation value determined by the time difference.

[0013] Furthermore, the step of determining the alveolar nitric oxide concentration and / or airway nitric oxide concentration of the exhaled gas sample based on the segmental concentration information of nitric oxide includes: determining a target value based on multiple concentration values ​​in the segmental concentration information; the target value includes one of the following: maximum concentration value, minimum concentration value, average concentration value, integral value of concentration information over time, integral value of concentration information over time within a specified time period, total alveolar nitric oxide, percentage of alveolar nitric oxide in the total nitric oxide during the entire exhalation phase, and nitric oxide concentration at a specified flow rate; and using the target value as the alveolar nitric oxide concentration and / or airway nitric oxide concentration of the exhaled gas sample.

[0014] Secondly, this application also provides a nitric oxide concentration detection system, comprising: a sampling pipeline, a sampling drive unit, a detection system including a nitric oxide detection unit and a characteristic timing information detection unit, and a control unit; the sampling pipeline, connected to a mechanical ventilation device, for collecting gas from the breathing tubing of the mechanical ventilation device under continuous monitoring; the sampling drive unit, connected to the sampling pipeline, for extracting exhaled gas samples from the breathing tubing to the detection system; and the characteristic timing information detection unit, connected to the sampling pipeline, for detecting the characteristic timing information of carbon dioxide in the exhaled gas samples; nitric oxide... The nitrogen detection unit, connected to the sampling pipeline, is used to detect the temporal characteristic information of nitric oxide in the exhaled gas sample. The control unit, connected to the characteristic temporal information detection unit and the nitric oxide detection unit respectively, is used to determine the alveolar gas segment and / or airway gas segment in the exhaled gas based on the characteristic temporal information of carbon dioxide; determine the segmental concentration information of nitric oxide in the exhaled gas based on the temporal characteristic information of nitric oxide and the alveolar gas segment and / or airway gas segment; and determine the alveolar gas nitric oxide concentration and / or airway gas nitric oxide concentration of the exhaled gas sample based on the segmental concentration information of nitric oxide.

[0015] Furthermore, the sampling tubing is connected to the Y-connector of the breathing tubing; or, the sampling tubing is connected to the expiratory branch of the breathing tubing.

[0016] Furthermore, the aforementioned feature timing information detection unit includes one or more of the following: carbon dioxide detection unit, flow rate detection unit, pressure detection unit, and capacity detection unit.

[0017] Furthermore, the above detection system also includes a breathing judgment unit, which includes a carbon dioxide detection unit, a flow detection element, a pressure detection element, or a volume detection element.

[0018] Furthermore, the aforementioned flow detection element, pressure detection element, or volume detection element is arranged at the Y-connector of the breathing tubing or at the expiratory branch; if arranged at the Y-connector, the respiratory status is determined by monitoring the forward / reverse flow, or forward / reverse pressure, or forward / reverse volume in the expiratory tubing; if arranged at the expiratory branch, the respiratory status is determined by monitoring the increase in flow, or increase in pressure, or increase in volume in the expiratory tubing.

[0019] Furthermore, the aforementioned nitric oxide detection unit and carbon dioxide detection unit are connected in parallel or in series.

[0020] The method and system for detecting nitric oxide concentration provided in this application first collects exhaled gas samples from the breathing tubing of a mechanical ventilation device; then, it detects the characteristic temporal information of carbon dioxide and the temporal characteristic information of nitric oxide in the exhaled gas samples; based on the characteristic temporal information of carbon dioxide, it determines the alveolar gas segment and / or airway gas segment in the exhaled gas samples; based on the temporal characteristic information of nitric oxide and the alveolar gas segment and / or airway gas segment, it determines the segmental concentration information of nitric oxide in the exhaled gas samples; finally, based on the segmental concentration information of nitric oxide, it determines the alveolar nitric oxide concentration and / or airway nitric oxide concentration of the exhaled gas samples. This method is suitable for continuous monitoring of alveolar nitric oxide (NO) concentration in patients with non-voluntary breathing. By analyzing the characteristic temporal information of carbon dioxide and nitric oxide in exhaled gas samples, it identifies alveolar and / or airway segments based on the carbon dioxide temporal information. Furthermore, it determines the segmental concentration information corresponding to the alveolar and / or airway segments within the nitric oxide temporal concentration information. Based on the segmental concentration information, the final alveolar / airway NO concentration is determined. This enables continuous monitoring of exhaled NO concentration in critically ill patients and accurately identifies and detects alveolar and airway NO concentration information, providing continuous data support for subsequent treatment pathway selection and thus improving diagnostic accuracy. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the specific embodiments of this application or the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0022] Figure 1 A flowchart illustrating a method for detecting nitric oxide concentration provided in an embodiment of this application;

[0023] Figure 2 A schematic diagram of a carbon dioxide concentration curve provided in an embodiment of this application;

[0024] Figure 3 This is a schematic diagram of concentration comparison provided in an embodiment of this application;

[0025] Figure 4 This application provides an interface for performing time difference compensation of carbon dioxide content information in a device according to an embodiment of the present application;

[0026] Figure 5 This application provides an interface for time difference compensation of nitric oxide concentration information in a device.

[0027] Figure 6 A flow-time curve provided for an embodiment of this application;

[0028] Figure 7 A schematic diagram of a nitric oxide concentration detection system provided in an embodiment of this application;

[0029] Figure 8 A schematic diagram of another nitric oxide concentration detection system provided in an embodiment of this application;

[0030] Figure 9 This is a schematic diagram of the structure of a nitric oxide detection unit provided in an embodiment of this application;

[0031] Figure 10 This is a schematic diagram of another nitric oxide detection unit provided in an embodiment of this application;

[0032] Figure 11 This is a schematic diagram of the structure of a carbon dioxide detection unit provided in an embodiment of this application. Detailed Implementation

[0033] The technical solutions of this application will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0034] In the existing technology, there is a complete alveolar nitric oxide detection procedure for patients with spontaneous breathing; however, for patients with non-spontaneous breathing, such as those using mechanical ventilation equipment such as ventilators, they cannot control their breathing movements and cannot cooperate with the routine exhaled nitric oxide concentration detection procedure. Therefore, how to detect alveolar nitric oxide concentration in these patients has always been an unsolved clinical problem.

[0035] Based on this, the present application provides a method and system for detecting nitric oxide concentration, which can be adapted to the detection of alveolar nitric oxide concentration in patients with non-voluntary breathing, and can improve the accuracy of concentration detection.

[0036] To facilitate understanding of this embodiment, a method for detecting nitric oxide concentration disclosed in this application embodiment will first be described in detail.

[0037] Figure 1 A flowchart of a method for detecting alveolar nitric oxide concentration provided in this application embodiment is included, and the method specifically includes the following steps:

[0038] Step S102: Collect exhaled gas samples from the breathing tubing of the mechanical ventilation device;

[0039] In practical applications, the first step is to determine the breathing state corresponding to the gas in the breathing tubing. If it is inhalation, no sample gas is collected or subsequent tests are performed. If it is determined to be exhalation, sample gas is collected. Specifically, sample gas can be continuously collected when there is exhaled gas in the breathing tubing of the mechanical ventilation device.

[0040] Step S104: Detect the temporal characteristics of carbon dioxide and nitric oxide in the exhaled gas sample.

[0041] The aforementioned time-series information on carbon dioxide includes one or more of the following: time-series carbon dioxide content in exhaled gas samples, time-series exhaled gas flow rate, time-series exhaled gas volume, time-series exhaled gas pressure, and time-series exhaled gas volume. The aforementioned time-series content information represents the change in carbon dioxide content over time in continuously collected exhaled gas samples.

[0042] The temporal characteristics of nitric oxide include: nitric oxide temporal concentration information, nitric oxide temporal partial pressure information, or nitric oxide temporal volume information.

[0043] Step S106: Based on the characteristic temporal information of carbon dioxide, determine the alveolar air segment and / or airway air segment in the exhaled gas sample.

[0044] In practice, the changes in carbon dioxide content over time can be detected to determine the alveolar air segment and the airway air segment; this segment is actually a time period.

[0045] Step S108: Determine the segmental concentration information of nitric oxide in the exhaled gas sample based on the temporal characteristic information of nitric oxide and the alveolar gas segment and / or airway gas segment.

[0046] The temporal characteristic information of nitric oxide here can be temporal concentration information; the temporal concentration information of nitric oxide and the characteristic temporal information of carbon dioxide are detected simultaneously, that is, they can correspond in time, or there is a certain delay, which can be compensated to make them correspond in time. Therefore, the nitric oxide concentration information corresponding to the alveolar air segment and / or airway air segment can be determined from the temporal concentration information of nitric oxide, that is, the above-mentioned segment concentration information.

[0047] Step S110: Determine the alveolar nitric oxide concentration and / or airway nitric oxide concentration of the exhaled gas sample based on the nitric oxide segment concentration information.

[0048] Finally, based on the nitric oxide concentration information corresponding to the alveolar gas segment and / or airway gas segment, the final alveolar gas nitric oxide concentration and / or airway gas nitric oxide concentration of the exhaled gas sample are determined.

[0049] The nitric oxide concentration detection method provided in this application embodiment is applicable to the continuous detection of alveolar / airway nitric oxide concentration in patients with non-voluntary breathing. By detecting the characteristic time-series information of carbon dioxide and the time-series characteristic information of nitric oxide in exhaled gas samples, the alveolar / airway gas segments are determined based on the characteristic time-series information of carbon dioxide. Furthermore, the segment concentration information corresponding to the alveolar / airway gas segments in the time-series concentration information of nitric oxide is determined, and the final alveolar / airway nitric oxide concentration is determined based on the segment concentration information.

[0050] Furthermore, this application embodiment also provides another method for detecting nitric oxide concentration, which is implemented based on the above embodiment. This embodiment focuses on describing the process of determining the alveolar air / airway air segment and the process of determining the final nitric oxide concentration.

[0051] The steps described above, based on the characteristic temporal information of carbon dioxide, to determine the alveolar air segments and / or airway air segments in exhaled gas samples, include:

[0052] (1) Based on the time-series information on carbon dioxide content, a carbon dioxide content curve is generated; wherein, the carbon dioxide content curve is used to characterize the correspondence between carbon dioxide content and time; see [link to relevant documentation]. Figure 2 As shown, the horizontal axis represents the collection time, and the vertical axis represents the carbon dioxide content.

[0053] The carbon dioxide content mentioned above refers to the concentration or volume percentage of carbon dioxide in the exhaled gas sample, or the partial pressure of carbon dioxide expressed in units such as mmHg, cmH2O, kPa.

[0054] (2) In the detection of carbon dioxide content curve, the first time period from the curve value to the inflection point of the curve rising stage, and the second time period from the inflection point of the curve rising stage to the end of the curve rising stage.

[0055] like Figure 2 As shown in the figure, point A corresponds to the moment when the curve value is zero, that is, the starting moment when the carbon dioxide content is 0; point B corresponds to the moment when the inflection point of the carbon dioxide content rises; point C corresponds to the moment when the carbon dioxide content rises; the interval from point A to point B is the first time period; the interval from point B to point C is the second time period.

[0056] (3) The first time period is defined as the airway air segment, and the second time period is defined as the alveolar air segment;

[0057] The first time period from point A to point B corresponds to the airway air segment; the second time period from point B to point C corresponds to the alveolar air segment.

[0058] Furthermore, the step of determining the segmental concentration information of nitric oxide in an exhaled gas sample based on the characteristic temporal information of nitric oxide and the alveolar gas segment and / or airway gas segment includes:

[0059] (1) Based on the temporal characteristics of nitric oxide, a nitric oxide concentration curve is generated; wherein, the nitric oxide concentration curve is used to characterize the correspondence between nitric oxide concentration and time; the nitric oxide concentration curve is as follows: Figure 3 As shown in the figure above, the horizontal axis represents the collection time, and the vertical axis represents the nitric oxide concentration.

[0060] (2) Detect the target concentration curve segment corresponding to the alveolar air segment from the nitric oxide concentration curve; and / or detect the target concentration curve segment corresponding to the airway air segment from the nitric oxide concentration curve.

[0061] like Figure 3 The carbon dioxide content curve shown in the lower figure can be aligned with the nitric oxide concentration curve along the time axis. This allows us to determine that the nitric oxide concentration curve segment between the first two vertical dashed lines corresponds to the alveolar air segment, while the nitric oxide concentration curve segment between the last two vertical dashed lines corresponds to the airway air segment.

[0062] It should be noted that, Figure 3 The process of aligning the two curves shown to determine the target concentration curve segment is merely for illustration and to facilitate understanding of the principle. In practical applications, the target concentration curve segment can be directly obtained from the nitric oxide concentration curve by using the alveolar air segment and / or airway air segment determined above, based on the time period.

[0063] (3) The nitric oxide concentration information corresponding to the target concentration curve segment is determined as the segment concentration information of nitric oxide in the exhaled gas sample.

[0064] Corresponding the temporal concentration information of carbon dioxide in the sample gas to the temporal concentration information of nitric oxide can be done according to the sample gas collection time. Based on the previously determined alveolar gas segment / airway gas segment, the concentration information of the corresponding time segment is determined from the nitric oxide temporal concentration curve as the segmental concentration information of nitric oxide.

[0065] In some cases, the timing of the carbon dioxide detection unit and the nitric oxide detection unit contacting and detecting the sample gas is not synchronized, and there may be a certain delay (such as when the nitric oxide detection unit and the nitric oxide detection unit are connected in series); or when the alveolar gas segment is determined using flow curves, pressure curves, etc., there may also be a certain delay between the time period when the nitric oxide detection unit detects the concentration curve in the sample gas.

[0066] When there is a delay, the start and end times of the determined target concentration curve segment do not correspond to the time of the nitric oxide concentration curve, which will cause the equipment to be inaccurate in judging and capturing alveolar gas concentration segments and airway gas concentration segments.

[0067] Therefore, time zone compensation is required in this situation.

[0068] That is, the above-mentioned step of determining the segmental concentration information of nitric oxide in exhaled gas samples based on the temporal characteristic information of nitric oxide and the alveolar gas segment and / or airway gas segment further includes:

[0069] (1) Perform temporal compensation on alveolar air segments and / or airway air segments; temporal compensation includes shifting the segment time forward or backward;

[0070] In practice, a fixed timing compensation value is set before the equipment leaves the factory, or the time difference is calculated using a preset algorithm during equipment operation. Based on the timing compensation value determined by the time difference, the time of the alveolar air segment / airway air segment is shifted forward or backward accordingly to achieve the compensation effect. These two compensation methods are described in detail below:

[0071] The first method is to set a fixed timing compensation value before the equipment leaves the factory (because once the structure and piping of the equipment are finalized, the timing delay between the nitrogen dioxide detection unit and the nitric oxide detection unit is a predictable fixed value that can be tested in advance and input into the equipment). Based on this timing compensation value, the time of the alveolar air segment / airway air segment is shifted forward or backward by the corresponding value.

[0072] The second method involves calculating the time difference using an algorithm while the device is running and then compensating for it.

[0073] In practice, the time-series flow information of exhaled air can be detected, and a flow-time curve can be generated based on the time-series flow information of exhaled air; the flow curve is used to characterize the correspondence between exhaled air flow and time.

[0074] In the flow-time curve, select at least one characteristic point and record its corresponding time point;

[0075] Find the time points corresponding to the relevant characteristic points on the carbon dioxide content curve and the nitric oxide concentration curve, and determine the compensation value based on the difference between the time points (such as the difference between the time point on the carbon dioxide content curve and the time point on the flow-time curve, and the difference between the time point on the nitric oxide concentration curve and the time point on the flow-time curve).

[0076] The following are some specific implementation methods:

[0077] Method 1:

[0078] The time-series compensation for carbon dioxide content information is as follows:

[0079] Figure 4 The interface for time difference compensation of carbon dioxide content information in the device is shown. The point with the largest downward slope at the end of expiration in the flow-time curve is selected as the feature point, and its corresponding time point is recorded. The corresponding point with the largest downward slope (within the same respiratory cycle) in the carbon dioxide concentration curve is selected and its corresponding time point is recorded. The compensation for the time point in the carbon dioxide content curve is determined based on the difference between the two time points. The time values ​​corresponding to the abscissa of the alveolar air segment and the airway air segment determined by the carbon dioxide content curve are compensated and adjusted using the above compensation value.

[0080] The time-series compensation for nitric oxide concentration is as follows:

[0081] Figure 5 The interface for time difference compensation of nitric oxide concentration information in the device is shown. Similarly, the point with the largest downward slope at the end of expiration in the flow-time curve is taken as the feature point, and its corresponding time point is recorded. The point with the largest downward slope at the end of expiration in the nitric oxide concentration curve (within the same respiratory cycle) is also taken and its corresponding time point is recorded. The compensation for the time point in the nitric oxide content curve is determined based on the difference between the two time points. The horizontal axis (time value) of the nitric oxide concentration curve is compensated and adjusted according to the above compensation value. Then, the alveolar NO concentration information and airway NO concentration information are determined corresponding to the alveolar gas segment time (after compensation adjustment) and the airway gas segment time (after compensation adjustment).

[0082] Method 2:

[0083] See Figure 6 As shown, the third time corresponding to a flow-time curve value of zero is as follows: Figure 6 Point E in the curve, and the fourth time corresponding to the curve value returning to zero, as shown in the figure. Figure 6 Point F in the middle; the third time and the fourth time are used as the start time and end time of the segment, respectively, to obtain the start time and end time of exhalation of the exhaled gas sample collection; the alveolar gas segment and the airway gas segment are compensated for time sequence based on the end time and start time of exhalation.

[0084] (2) From the nitric oxide concentration curve, detect the target concentration curve segment corresponding to the alveolar air segment after time compensation; and / or from the nitric oxide concentration curve, detect the target concentration curve segment corresponding to the airway air segment after time compensation.

[0085] (3) The nitric oxide concentration information corresponding to the target concentration curve segment is determined as the segment concentration information of nitric oxide in the exhaled gas sample.

[0086] Here's a specific example: using the carbon dioxide concentration curve to determine the segments is mainly to determine the horizontal axis value, i.e., the time. For instance, using the carbon dioxide concentration curve to determine that the alveolar air segment is 2-7s and the airway air segment is 0-2s, assuming no time difference compensation is needed, then we find the 2-7s horizontal axis time interval on the nitric oxide concentration curve. The vertical axis concentration information within this interval is the segmental concentration information of nitric oxide in the alveolar air segment. Similarly, the vertical axis concentration information corresponding to the 0-2s horizontal axis time interval on the nitric oxide concentration curve is the segmental concentration information of nitric oxide in the airway air segment.

[0087] Assuming time difference compensation is needed, with a one-second time difference offset, then the horizontal axis of the nitric oxide concentration curve should be set to a time interval of 3-8 seconds. The vertical axis concentration information within this interval represents the segmental concentration information of nitric oxide in the alveolar air segment. The same principle applies to the airway air segment.

[0088] Furthermore, the steps described above for determining the alveolar nitric oxide concentration and / or airway nitric oxide concentration of exhaled gas sample based on the segmental concentration information of nitric oxide include:

[0089] Based on multiple concentration values ​​in the segment concentration information, a target value is determined; the target value includes one of the following: maximum concentration value, minimum concentration value, average concentration value, the integral value of concentration information with time at a specified time point (e.g., 5 seconds) or within a specified time period (e.g., 3-8 seconds, or other time periods), total alveolar nitric oxide, the percentage of alveolar nitric oxide in the total nitric oxide in the entire exhalation phase, and the nitric oxide concentration at a specified flow rate; the target value is used as the alveolar nitric oxide concentration and / or airway nitric oxide concentration of the exhaled gas sample.

[0090] Optionally, before the above-mentioned step of collecting exhaled gas samples from the breathing tubing of the mechanical ventilation device, the method further includes: collecting gas from the breathing tubing; determining the breathing state corresponding to the gas in the breathing tubing; continuing to collect exhaled gas samples from the breathing tubing of the mechanical ventilation device when the breathing state is determined to be exhalation; and stopping sample collection and detection when the breathing state is determined to be inhalation.

[0091] It should be noted that during continuous monitoring, the step of determining respiratory status does not necessarily have to be set before the air sampling step. It is sufficient to determine the respiratory status before identifying the alveolar air / airway air segment.

[0092] The nitric oxide concentration detection method provided in this application is applicable to the continuous detection of alveolar nitric oxide concentration in patients with non-voluntary breathing. By detecting the characteristic temporal information of carbon dioxide and nitric oxide in exhaled gas samples, alveolar gas segments and / or airway gas segments are determined based on the characteristic temporal information of carbon dioxide. Furthermore, the segmental concentration information corresponding to the alveolar gas and / or airway gas segments in the temporal concentration information of nitric oxide is determined. Based on the segmental concentration information, the final alveolar / airway nitric oxide concentration is determined. This method enables continuous monitoring of exhaled NO concentration in critically ill patients and can accurately identify and detect alveolar and airway NO concentration information, providing continuous data support for the selection of subsequent treatment pathways and thus improving diagnostic accuracy.

[0093] Based on the above method embodiments, this application also provides a nitric oxide concentration detection system, see [link to relevant documentation]. Figure 7 As shown, the system includes: a sampling pipeline 1, a sampling drive unit 2, a detection system 5 including a nitric oxide detection unit 3 and a feature timing information detection unit 4, and a control unit 6;

[0094] Sampling tubing 1 is connected to mechanical ventilation equipment 7 and is used to collect gas from breathing tubing 8 of mechanical ventilation equipment 7 under continuous monitoring;

[0095] The sampling drive unit 2 is connected to the sampling pipeline 1 and is used to draw exhaled gas sample from the breathing pipeline 8 to the detection system 5;

[0096] The feature timing information detection unit 4 is connected to the sampling pipeline 1 and is used to detect the feature timing information of carbon dioxide in the exhaled gas sample.

[0097] The nitric oxide detection unit 3 is connected to the sampling pipeline 1 and is used to detect the temporal characteristics of nitric oxide in the exhaled gas sample.

[0098] The control unit 6 is connected to the feature timing information detection unit 4 and the nitric oxide detection unit 3, respectively, and is used to determine the alveolar gas segment and / or airway gas segment in the exhaled gas based on the feature timing information of carbon dioxide; determine the segment concentration information of nitric oxide in the exhaled gas based on the timing feature information of nitric oxide and the alveolar gas segment and / or airway gas segment; and determine the alveolar gas nitric oxide concentration and / or airway gas nitric oxide concentration of the exhaled gas sample based on the segment concentration information of nitric oxide.

[0099] Furthermore, the sampling tubing 1 is connected to the Y-connector 9 of the breathing tubing 8; or, the sampling tubing 1 is connected to the expiratory branch 10 of the breathing tubing 8. The breathing tubing 8 also includes an inspiratory branch 12.

[0100] In a preferred embodiment, the aforementioned feature timing information detection unit 4 includes one or more of a carbon dioxide detection unit, a flow detection unit, a pressure detection unit, and a volume detection unit. The flow detection unit and the pressure detection unit can be used to determine the breathing state corresponding to the gas.

[0101] Optionally, the above detection system further includes: a breathing judgment unit 11, which is connected to the breathing tubing 8. The breathing judgment unit 11 includes: a carbon dioxide detection unit or a flow detection element or a pressure detection element or a volume detection element; the flow detection element or pressure detection element or volume detection element is arranged at the Y-type connector of the breathing tubing or at the expiratory branch.

[0102] If placed at a Y-connector, the respiratory status is determined by monitoring the forward / reverse flow rate, forward / reverse pressure, or forward / reverse volume in the expiratory tubing; if placed at an expiratory branch, the respiratory status is determined by monitoring the increase in flow rate, pressure, or volume in the expiratory tubing.

[0103] Furthermore, the nitric oxide detection unit 3 and the carbon dioxide detection unit 4 are connected in parallel or in series. Figure 7 The middle is in a parallel state. Figure 8 The middle part is in series.

[0104] Taking a system in parallel with a nitric oxide detection unit and a feature time-series information detection unit (such as a carbon dioxide detection unit) as an example:

[0105] When exhalation is detected, the sample gas is collected and enters the sampling pipeline under the drive of the sampling drive unit (vacuum pump of nitric oxide detection unit and diaphragm pump of carbon dioxide detection unit). After being filtered to remove water vapor and droplets, the sample gas enters the nitric oxide detection unit and carbon dioxide detection unit respectively.

[0106] When the nitric oxide detection unit is in operation:

[0107] Sample gas input: Driven by the pump, the sample gas from the gas sampling pipeline enters the gas inlet passage through the sample gas inlet, and enters the reaction chamber at the reaction end at a constant flow rate under the flow restriction of the flow restrictor four; for example, in this embodiment, the flow rate allowed by the flow restrictor four is 90-130 ml / min (for children) or 300-360 ml / min (for adults).

[0108] Ozone input: Driven by the pump, air enters the ozone gas path through the air inlet. After passing through the filter (particulate filter) to filter out particles larger than 5μm, the air enters the inner tube of the permeate dryer. Under the pressure difference between the inner and outer tubes, water vapor permeates from the inner tube wall to the outer tube. The dried air after passing through the dryer enters the ozone preparation device. O2 in the dried air entering the ozone preparation device is converted into O3. After passing through the flow restrictor three, it enters the reaction chamber at the reaction end. The flow restrictor three allows the gas flow rate to be 30-70 ml / min.

[0109] Detection: The sample gas and ozone undergo a chemiluminescent reaction at the reaction end. The PMT end captures the photons generated by the reaction, thereby obtaining an electrical signal related to the NO concentration in the sample gas, and transmitting the electrical signal to the control unit of the detection system.

[0110] Reflux purging: Further, the dried air after passing through the dryer is also refluxed back to the outer tube of the dryer through the first gas path driven by the pump. The flow restrictor of the first gas path allows the gas flow rate to be 70 ml / min.

[0111] Exhaust gas: The exhaust gas after the reaction at the reaction end is discharged through the outlet of the reaction end under the drive of the pump. After being processed by the exhaust gas processor, it is pumped again and finally discharged from the outlet.

[0112] When the carbon dioxide detection unit is in operation:

[0113] Driven by a diaphragm pump, the sample gas from the gas sampling pipeline enters the gas inlet through the sample gas inlet, then enters the infrared analysis chamber to detect the CO2 concentration. The electrical signal related to the CO2 concentration is transmitted to the control unit of the detection system, and then discharged after passing through a flow meter and the diaphragm pump. The diaphragm pump controls the flow rate of the sample gas through the carbon dioxide detection unit to be 20–100 ml / min.

[0114] After obtaining the temporal concentration information of nitric oxide and carbon dioxide, the control unit determines the time segment of alveolar gas based on the inflection point of carbon dioxide concentration change. The nitric oxide concentration information corresponding to this time segment is the alveolar gas nitric oxide concentration information. Then, the alveolar gas nitric oxide concentration value is calculated and output according to one of the following methods:

[0115] (1) Take the maximum value from the concentration information as the alveolar NO concentration value; or,

[0116] (2) Take the minimum value from the concentration information as the alveolar NO concentration value; or,

[0117] (3) Take the average value of the concentration information as the alveolar gas concentration value; or,

[0118] (4) Use the concentration information and the time integral as the alveolar gas concentration value; or,

[0119] (5) Take the value of the nitric oxide concentration information and time integral within the first n seconds of the alveolar gas segment as the alveolar gas concentration value (this method is applicable to alveolar NO detection in expiratory maintenance mode). Preferably, n≤10 seconds. For example, in some embodiments, n can be 1 second, 1.5 seconds, 2 seconds, 2.5 seconds, 3 seconds, 3.5 seconds, 4 seconds, 4.5 seconds, 5 seconds, 5.5 seconds, 6 seconds, 6.5 seconds, 7 seconds, 7.5 seconds, 8 seconds, 8.5 seconds, 9 seconds, 9.5 seconds or 10 seconds, but is not limited to these. Specifically, n=5 can be taken.

[0120] In this embodiment, the nitric oxide detection unit 3 is used to detect the time-series concentration information of nitric oxide in the sample gas in real time. Detection can be performed in two ways: first, by directly responding to the nitric oxide component in the sample gas to obtain the nitric oxide concentration information; second, such as chemiluminescence, by detecting excited-state NO2. * The system responds to obtain light signal information, which is then converted to obtain nitric oxide concentration information.

[0121] Specifically, the T90 response time of the nitric oxide detection unit 3 to nitric oxide is ≤1000 milliseconds.

[0122] Specifically, the nitric oxide detection unit 3 can be an electrochemical sensor, a chemiluminescence detection unit, or a laser spectroscopy detection unit, etc.

[0123] Figure 9 The specific structure of the nitric oxide detection unit 3 when it is a chemiluminescence detection unit is shown. The nitric oxide detection unit 3 includes:

[0124] Ozone gas path 31 is used to pass ozone-containing gas to the reaction end of the detection module;

[0125] Inlet passage 32 is used to supply sample gas to the reaction end of the detection module;

[0126] Exhaust passage 33 is used to discharge waste gas.

[0127] The detection module 34 includes a reaction end 341 and a PMT end 342. The reaction end performs a chemiluminescence reaction, and the PMT end captures the photons generated by the reaction.

[0128] First gas path 35 and calibration gas path 36.

[0129] See Figure 10 The ozone path 31, the inlet path 32, the outlet path 33, and the detection module 34 described above will be introduced in detail:

[0130] (1) Ozone circuit 31:

[0131] The ozone gas flow path includes an inlet 311, a dryer 312, and an ozone generating device 313 connected in sequence. Air enters through the inlet, is dried by the dryer 312, and then enters the ozone generating device 313, where O2 is converted into O3. The O3 is then introduced into the reaction end 341 through the ozone inlet. A first filter 314 can be installed upstream of the dryer 312 to filter particulate matter in the incoming air, preventing it from affecting the service life and effectiveness of subsequent structures. A first flow meter 315 can be installed on the ozone gas flow path (such as upstream of the ozone generating device 313) to monitor the gas flow rate. A first flow limiter 316 is installed on the ozone gas flow path downstream of the ozone generating device 313 to control the flow rate of ozone-containing gas entering the reaction end 341.

[0132] (2) Intake passage 32:

[0133] The inlet passage is connected to the sampling pipeline. The sample gas enters the reaction end 341 through the sample gas inlet port of the inlet passage. A second flow meter 321 can be installed on the inlet passage to monitor the flow rate of the sample gas. A second flow limiter 322 is provided on the inlet passage to control the flow rate of the sample gas entering the reaction end 341.

[0134] (3) Exhaust passage 33:

[0135] One end of the gas outlet passage is connected to the gas outlet 332 of the reaction end 341 via the first pump 331, and the other end is connected to the environment to discharge the gas from the reaction end 341. A waste gas processor 333 is installed on the gas outlet passage, the main purpose of which is to treat the ozone in the gas discharged from the reaction end 341 to prevent pollution.

[0136] First airway 35:

[0137] The dryer in this solution is a permeation dryer (an existing structure with a sleeve structure, the inner tube being a permeation membrane and the outer tube being a Teflon tube; air passes through the inner tube, and under the pressure difference between the inner and outer tubes, water vapor permeates from the inner tube wall to the outer tube, thereby achieving the effect of drying the air). The inner tube of the dryer is connected to the ozone gas circuit.

[0138] This design incorporates a first gas path 35 within the ozone gas path. The inlet of the first gas path 35 is located upstream of the ozone generating device 313 (downstream of the dryer) on the ozone gas path, and the outlet of the first gas path 35 is connected to the outer tube of the dryer. Through this first gas path design, during the drying process, a portion of the air dried by the dryer will enter the outer tube of the dryer via the first gas path, purging water vapor from the outer tube and preventing water vapor accumulation that could reduce the drying effect.

[0139] Furthermore, this solution includes a third flow limiter 351 in the first air path to limit the flow rate of dry air passing through the first air path.

[0140] Preferably, the flow rate allowed by the flow restrictor is 50-300 ml / min. If no flow restrictor is installed or the flow rate allowed by the flow restrictor is too large, the vacuum at the reaction end 341 will be insufficient. This is because most of the drying air enters the outer tube through the first gas path and is then discharged, leaving insufficient vacuum in other gas paths. This affects the gas flow requirements of other gas paths, resulting in insufficient vacuum at the reaction end 341 and insufficient ozone-containing air entering. If the flow rate allowed by the flow restrictor is too small, the flow rate of drying air entering the outer tube will be too small, and the improvement in the drying effect of the dryer will not be significant.

[0141] First pump 331: The pump installed on the gas outlet passage is a component of the sampling drive unit, one of its functions being to provide driving force for the flow of sample gas in the nitric oxide detection unit.

[0142] Furthermore, the outlet of the dryer's outer tube is connected to the outlet passage upstream of the pump. This connection creates a pressure difference between the inner and outer tubes of the dryer, meeting the dryer's operating conditions. In this scheme, the flow of gas in each path of the nitric oxide detection unit primarily relies on the pump's operation, generating negative pressure in each gas path and thus driving the corresponding gas flow. During pump operation, a certain degree of vacuum exists in the upstream outlet passage, the reaction chamber at reaction end 341, and the ozone gas path, enabling directional gas flow within each path.

[0143] Furthermore, the exhaust gas processor 333 is positioned upstream of the pump in the exhaust passage. Ozone is corrosive, and placing the exhaust gas processor upstream of the pump helps extend the pump's service life.

[0144] Furthermore, a calibration gas path 36 is included for periodically calibrating the detection module. This calibration gas path is selectively connected to the intake passage, more precisely, to the intake passage upstream of the second flow limiter. The calibration gas path sequentially includes a standard gas inlet 361, a pressure reducing valve 362, a second filter 363, and a fourth flow limiter 364. The standard gas inlet is used to supply standard gas. Further, an exhaust port 365 is provided downstream of the fourth flow limiter 364 in the calibration gas path to discharge excess standard gas. Under the action of the pressure reducing valve 362, the fourth flow limiter 364, and the second flow limiter 322, the standard gas entering the reaction end 341 is ensured to be at constant pressure and flow, ensuring the effectiveness of the standard gas calibration.

[0145] See Figure 11As shown, the carbon dioxide detection unit 4 includes, in sequence, an inlet passage 41, a detection chamber 42, a third flow meter 43, a second pump 44, and an outlet 45. The inlet passage 41 is connected to the sampling pipeline and is used to introduce sample gas; the detection chamber 42 can be an infrared detection chamber, etc., used to detect the carbon dioxide concentration in the sample gas; the third flow meter 43 can be a flow sensor, differential pressure sensor, etc., used to detect the flow rate in the passage; the second pump 44 can be a diaphragm pump, used to draw sample gas from the sampling pipeline into the inlet passage.

[0146] In another preferred embodiment, the detection system further includes a zero-point calibration path connected to the sampling pipeline. The zero-point calibration path sequentially includes an air inlet connected to the environment, a filter, a fan, and a one-way valve. When the fan is started, ambient air is drawn into the zero-point calibration path; the filter is used to filter NO and / or CO2 from the ambient air; the one-way valve allows gas to flow only from the zero-point calibration path to the sampling pipeline. The zero-point calibration path allows for periodic zero-point calibration of the nitric oxide detection unit and / or carbon dioxide detection unit.

[0147] The nitric oxide concentration detection system provided in this application embodiment can continuously detect NO in the exhaled air of patients who cannot control their breathing voluntarily, and can further accurately distinguish between airway air and alveolar air, and accurately detect the NO concentration in alveolar air / airway air.

[0148] The nitric oxide concentration detection system provided in this application has the same implementation principle and technical effect as the aforementioned method embodiment. For the sake of brevity, any parts not mentioned in the system embodiment section can be referred to the corresponding content in the aforementioned method embodiment.

[0149] In the description of this application, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0150] Finally, it should be noted that the above-described embodiments are merely specific implementations of this application, used to illustrate the technical solutions of this application, and not to limit them. The protection scope of this application is not limited thereto. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that any person skilled in the art can still modify or easily conceive of changes to the technical solutions described in the foregoing embodiments, or make equivalent substitutions for some of the technical features, within the technical scope disclosed in this application. Such modifications, changes, or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be covered within the protection scope of this application. Therefore, the protection scope of this application should be determined by the protection scope of the claims.

Claims

1. A method for detecting nitric oxide concentration, characterized in that, The method includes: Collect exhaled gas samples from the breathing tubing of a mechanical ventilation device; The characteristic temporal information and the temporal characteristic information of nitric oxide in the exhaled gas sample were detected. Based on the aforementioned time-series information, the alveolar air segment and / or airway air segment in the exhaled gas sample are determined. Based on the temporal characteristics of nitric oxide and the alveolar gas segment and / or airway gas segment, determine the segmental concentration information of nitric oxide in the exhaled gas sample. Based on the nitric oxide segment concentration information, determine the alveolar nitric oxide concentration and / or airway nitric oxide concentration of the exhaled gas sample.

2. The method according to claim 1, characterized in that, The time-series information includes one or more of the following: time-series carbon dioxide content information in exhaled gas sample, time-series flow rate information in exhaled gas, time-series flow rate information in exhaled gas, time-series pressure information in exhaled gas, and time-series volume information in exhaled gas.

3. The method according to claim 2, characterized in that, When the time-series characteristic information includes time-series content information, the step of determining the alveolar air segment and / or airway air segment in the exhaled gas sample based on the time-series characteristic information of carbon dioxide includes: Based on the time-series carbon dioxide content information, a carbon dioxide content curve is generated; wherein, the carbon dioxide content curve is used to characterize the correspondence between carbon dioxide content and time; The detection of the carbon dioxide content curve includes a first time period from the curve value starting at zero to the inflection point of the rising phase, and a second time period from the inflection point of the rising phase to the end of the rising phase. The first time period is defined as the airway air segment, and the second time period is defined as the alveolar air segment.

4. The method according to claim 1, characterized in that, The step of determining the segmental concentration information of nitric oxide in the exhaled gas sample based on the temporal characteristic information of nitric oxide and the alveolar gas segment and / or airway gas segment includes: Based on the time-series characteristics of nitric oxide, a nitric oxide concentration curve is generated; wherein, the nitric oxide concentration curve is used to characterize the correspondence between nitric oxide concentration and time. From the nitric oxide concentration curve, detect the target concentration curve segment corresponding to the alveolar air segment; and / or from the nitric oxide concentration curve, detect the target concentration curve segment corresponding to the airway air segment; The nitric oxide concentration information corresponding to the target concentration curve segment is determined as the segmental concentration information of nitric oxide in the exhaled gas sample.

5. The method according to claim 4, characterized in that, The step of determining the segmental concentration information of nitric oxide in the exhaled gas sample based on the temporal characteristic information of nitric oxide and the alveolar gas segment and / or airway gas segment further includes: Temporal compensation is performed on alveolar air segments and / or airway air segments; the temporal compensation includes shifting the segment time forward or backward. From the nitric oxide concentration curve, detect the target concentration curve segment corresponding to the alveolar air segment after time compensation; and / or from the nitric oxide concentration curve, detect the target concentration curve segment corresponding to the airway air segment after time compensation. The nitric oxide concentration information corresponding to the target concentration curve segment is determined as the segmental concentration information of nitric oxide in the exhaled gas sample.

6. The method according to claim 5, characterized in that, The steps for time-compensated alveolar air segments and / or airway air segments include: Based on a fixed timing compensation value set before the equipment leaves the factory, or by calculating the time difference through a preset algorithm during equipment operation, the timing compensation value determined based on the time difference is shifted forward or backward by the corresponding value.

7. The method according to claim 1, characterized in that, The step of determining the alveolar nitric oxide concentration and / or airway nitric oxide concentration of the exhaled gas sample based on the nitric oxide segment concentration information includes: Based on multiple concentration values ​​in the concentration information of the segment, a target value is determined; the target value includes one of the following: maximum concentration value, minimum concentration value, average concentration value, integral or differential value of concentration information over time, integral or differential value of concentration information over time within a specified time period, total alveolar nitric oxide, percentage of alveolar nitric oxide in the total nitric oxide in the entire exhalation phase, and nitric oxide concentration at a specified flow rate. The target value is used as the alveolar nitric oxide concentration and / or airway nitric oxide concentration of the exhaled gas sample.

8. A system for detecting nitric oxide concentration, characterized in that, The system includes: a sampling pipeline, a sampling drive unit, a detection system including a nitric oxide detection unit and a feature timing information detection unit, and a control unit; The sampling tubing is connected to the mechanical ventilation equipment and is used to collect gas from the breathing tubing of the mechanical ventilation equipment under continuous monitoring. The sampling drive unit is connected to the sampling pipeline and is used to extract exhaled gas sample from the breathing pipeline to the detection system; The feature timing information detection unit is connected to the sampling pipeline and is used to detect the feature timing information in the exhaled gas sample. The nitric oxide detection unit is connected to the sampling pipeline and is used to detect the temporal characteristic information of nitric oxide in the exhaled gas sample. The control unit is connected to the feature timing information detection unit and the nitric oxide detection unit, respectively, and is used to determine the alveolar gas segment and / or airway gas segment in the exhaled gas based on the feature timing information; determine the segment concentration information of nitric oxide in the exhaled gas according to the timing feature information of nitric oxide and the alveolar gas segment and / or airway gas segment; and determine the alveolar gas nitric oxide concentration and / or airway gas nitric oxide concentration of the exhaled gas sample according to the segment concentration information of nitric oxide.

9. The system according to claim 8, characterized in that, The sampling tubing is connected to the Y-connector of the breathing tubing; or, the sampling tubing is connected to the expiratory branch of the breathing tubing.

10. The system according to claim 8, characterized in that, The feature timing information detection unit includes one or more of the following: carbon dioxide detection unit, flow rate detection unit, pressure detection unit, and capacity detection unit.

11. The system according to claim 8, characterized in that, The detection system further includes a breathing judgment unit, which includes a carbon dioxide detection unit, a flow detection element, a pressure detection element, or a volume detection element.

12. The system according to claim 10 or 11, characterized in that, The flow detection element, or the pressure detection element, or the volume detection element is arranged at the Y-connector of the breathing tubing or at the expiratory branch. If placed at a Y-connector, the respiratory status is determined by monitoring the forward / reverse flow rate, forward / reverse pressure, or forward / reverse volume in the expiratory tubing; if placed at an expiratory branch, the respiratory status is determined by monitoring the increase in flow rate, pressure, or volume in the expiratory tubing.

13. The system according to claim 8, characterized in that, The nitric oxide detection unit and the feature timing information detection unit are connected in parallel or in series.

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