CN204269592U - Multi-parameter exhaled nitric oxide measuring device in one breath - Google Patents

Abstract

Disclose a kind of measurement mechanism of multiparameter expiration nitric oxide without a break, this device utilizes elongated tubular (ensureing that gas flowing is wherein piston flow when exhaling sampling and analysis to measure) with the expiration gas under the different expiratory duration (flow velocity) of fast speed synchronous collection in exhalation process, when analyzing to be passed through to carry out analysis to measure into sensor by the gas collected in elongated tubular compared with low flow velocity; Designed by gas circuit and make the NO concentration curve of sensor record corresponding with expiratory gas flow (time) curve to the control of gas flow ratio when sampling and measurement, thus realize utilizing the measurement of the electrochemical sensor of slow-response realization to fast-changing expiration NO concentration, and then calculate exhaled NO parameters according to expiration NO two compartment model.

Description

Multi-parameter exhaled nitric oxide measuring device in one breath

technical field

The present invention relates to a device for measuring exhaled nitric oxide.

Background technique

The use of exhaled nitric oxide as a marker of airway inflammation in the detection and analysis of asthma and other respiratory diseases has been fully affirmed by the medical community. The American Thoracic Society and the European Respiratory Society jointly developed and published a standardized method for this measurement in 2005 (“ATS/ERS recommendations for Standardized Procedures for the Online and Offline Measurement of Exhaled Low Respiratory Nitric Oxide and Nasal Nitric Oxide, 2005”) Its clinical application guidelines (An Official ATS Clinical Practice Guideline: Interpretation of exhaled Nitric Oxide Level (FeNO) for Clinical Applications) were proposed in 2011. These standards and guidelines are used to guide how to perform testing and use the testing results for respiratory diseases such as asthma diagnosis and efficacy evaluation.

Since exhaled NO is related to the expiratory flow rate and is easily interfered by nasal air, the standardized exhaled nitric oxide measurement method recommended by ATS/ERS is used to measure the inflammation of the lower respiratory tract. Under certain conditions, perform a single continuous exhalation for 10 seconds (or 6 seconds for children) at a fixed expiratory flow rate of 50ml/s. The main consideration for choosing an expiratory flow rate of 50ml/s is the contribution of exhaled NO at this flow rate. The main source is the airway, and it is easier to control exhalation.

The nitric oxide in exhaled breath comes from the alveoli and airways. If the NO concentration in different areas can be distinguished, it can be evaluated which pathological area the increased or decreased NO secretion occurs in, which has a wider clinical reference value.

Regarding the clinical significance of steady-state alveolar gas concentration, Hogman (J. Breath Res. 6 (2012) 047103) reviewed more than 100 documents before 2012, and its relationship with some diseases can be briefly summarized as follows:

1) In-depth diagnosis of asthma: Ca _NO in bronchial inflammation remains unchanged but Jaw increases, and Ca _NO in bronchiolary inflammation increases;

2) Selection of asthma treatment options: inhaled hormone therapy is ineffective for bronchiolitis inflammation and oral hormone therapy should be taken;

3) COPD and smoking patients: Ca _NO in COPD patients is higher than that in the normal group, and smoking is not clear to the testers' Ca _NO ;

4) Systemic scleroderma: among patients with systemic scleroderma who have interstitial lung disease (ILD), Ca _NO is significantly elevated (with 10.8ppb as the cut-off point, the specificity can reach 96%, and Ca _NO can be used as a marker of ILD. landmark;

5) Alveolitis: Ca _NO increased but Jaw remained unchanged;

6) Pulmonary fibrosis: Ca _NO increased;

7) Hepatorenal syndrome: Ca _NO increased (8.3ppb vs 4.7ppb).

There are many literatures on the detection methods of breath nitric oxide. Hogman (J. Breath Res. 7 (2013) 017104) made a relatively comprehensive and objective introduction to the various existing measurement methods. Ca _NO can not be measured directly, it must be deduced and calculated through a certain physiological model. At present, there are mainly three models related to exhaled NO, namely: two-chamber model, three-chamber model and trumpet model, which can analyze three parameters that have nothing to do with flow: Steady-state alveolar concentration, airway wall diffusivity (or maximal airway wall flux), and airway wall concentration, where the horn model with axial diffusion is thought to provide a good description of flow-dependent NO production in the lung.

The two-compartment model (2CM) is the simplest physiological model of exhaled nitric oxide. It believes that the concentration of exhaled nitric oxide (Ce _NO ) is composed of two parts, which come from the alveolar area and the airway area respectively (as shown in Figure 1) , depends on three flow-dependent parameters: the total flow of NO from the airway wall (maximum airway wall flux Jaw _NO , pl/s), the diffusion capacity of NO in the airway (DawNO, pl*s ^- 1 *ppb ^- 1), and alveolar gas concentration (Ca _NO , ppb) at steady state. The maximum airway wall flux Jaw _NO (pl/s) is inversely proportional to the expiratory flow rate F; Caw _NO refers to the airway wall NO concentration.

The relationship between each parameter satisfies the following relationship:

(1)

When VE >5*DawNO ml/s or 50 ml/s (for healthy people), the equation can be simplified as

(2)

Generally speaking, Ca _NO <2% Caw _NO , and J'aw _NO =Daw _NO *Caw _NO , the above equation can be simplified as

(3)

Thus, by measuring the concentration of Ce _NO under different expiratory flow (F), the alveolar gas concentration Ca _NO and the maximum airway wall flux Jaw can be obtained.

Usually within the expiratory flow range of 100-500ml/s, the linear model (3) is used for analysis, and the two parameters of Ca _NO and Jaw _NO can be calculated. For wider expiratory flow, such as 10-500ml/s, the (1) nonlinear model analysis, can calculate Ca _NO , Jaw _NO, Caw _NO and Daw _NO four parameters.

This model can explain how the concentration of exhaled nitric oxide changes with the expiratory flow, and the experimental data is basically consistent with the theoretical value. Therefore, most of the work on the measurement of Jaw _NO and Ca _NO is based on this model. The method is to control different expiratory flow rates for multiple exhalations, measure the expiratory NO value at different flow rates, and then calculate according to formula (1) or (3).

Analyzing the measurement results of Ca _NO , Jaw _NO and Ce _NO in the literature, there is no significant difference in the Ca _NO and Jaw _NO calculated by different data processing methods, and the various data processing methods are basically equivalent. It is generally believed that the steady-state alveolar gas concentration of Ca _NO in normal adults is generally between 1.0-5.6ppb, and Jaw _NO is in the range of 420-1280pl/s ( J Appl Physiol 91: 2173–2181, 2001).

It is relatively easy to achieve continuous exhalation for 4~10s at an expiratory flow rate of 50ml/s, and a lower flow rate (for example, an expiratory flow rate of 10ml/s requires at least 20 seconds of exhalation at a constant flow rate) and a higher exhalation (The lower exhalation resistance is greater) It will be difficult to continue to exhale. For this reason, in 2001, the George team proposed a breath variable flow measurement technology ^[6] , he continuously adjusted the expiratory flow (from 300ml/s to 50ml /s), measure and record the relationship between expiratory flow and the timely follow-up expiratory NO concentration, and calculate Jaw _NO and Ca _NO according to the two-chamber model. But it was not until 2006 that Bruno designed the experiment for the first time to evaluate the consistency of multi-breath variable flow and one-breath variable flow methods (Respiratory Physiology & Neurobiology 153 (2006) 148–156), by performing Bland Altman statistics on the experimental data According to the analysis, it is considered that the measurement results of Jaw _NO and Ca _NO by the two methods are consistent, and at the same time, it is believed that the method of variable flow rate in one breath is simpler and more convenient.

However, due to the high requirement of sensor response time (<200ms) for this technology, currently only chemiluminescence can meet the requirement of this time resolution, and the low-cost but slow-response electrochemical NO sensor cannot meet this requirement.

Contents of the invention

The realization of the breath variable flow measurement method requires a high response speed of the sensor, and only a chemiluminescence analyzer can meet the time resolution requirement, but the chemiluminescence analyzer has a high cost, is difficult to maintain, and exhales at a relatively fast flow rate. The NO value is low, which is close to the detection limit of the chemiluminescence instrument, so the data quality cannot be guaranteed, and the measurement error is relatively large.

The idea of the present invention is to separate the sampling and measurement process through the design of the air circuit, and use the slender tube (to ensure that the flow of gas in it is a plug flow during the exhalation sampling and analysis measurement) to collect synchronously at a faster speed during the exhalation process. Part of the exhaled gas under different exhalation time (flow rate) is analyzed and measured by passing the gas collected in the slender tube through the sensor at a lower flow rate during analysis; through the design of the gas circuit and the ratio of the gas flow rate during sampling and measurement The control makes the NO concentration curve recorded by the sensor correspond to the expiratory flow (time) curve, so that the fast-changing expiratory NO concentration can be measured by using the slow-response electrochemical sensor.

To realize the above method, several key issues need to be considered and resolved in the design of the measuring device and the measurement method, specifically:

l Expiratory flow control: How to ensure that the subject continues to exhale within a certain period of time and ensure that the expiratory flow changes according to the law we want?

Regarding this point, the solution of the present invention is to combine the flow sensor and the flow controller into an automatic flow feedback control system. When the subject continues to exhale, the flow sensor measures the expiratory flow and transmits the data to the flow controller. The flow controller compares the data with the preset target flow, and adjusts the diameter of the exhalation pipeline in time (reduce the diameter when the flow rate is too large, and increase the diameter when the flow rate is too small), and its feedback The adjustment speed is less than 100ms. In this way, the rapid measurement of the expiratory flow and the timely adjustment of the pipeline path can basically ensure that the expiratory flow changes according to the preset flow change rule. For example, within 6 to 10 seconds, the expiratory flow Decrease linearly from 300ml/s to 20ml/s.

One way to control the change of expiratory flow is to make it linearly attenuate, such as linearly decreasing from 300ml/s to 20ml/s within 6 to 10 seconds. Of course, the upper and lower limits of expiratory flow can be adjusted according to actual needs. A major advantage of controlling the linear change of expiratory flow is that the algorithm model is relatively simple, and the aforementioned theoretical formula is derived under this condition.

Of course, it is also possible to control the expiratory flow rate to change exponentially or in any other way. The difference from the linear change of the expiratory flow rate is the difference in algorithm processing. The flow rate that changes regularly in a linear or exponential manner can be solved in an algorithmic formula. When the expiratory flow changes irregularly, the solution is more complicated, and the numerical integration algorithm may be an unavoidable choice.

2 Sampling method design: collect all the exhaled gas for analysis and measurement, or only collect and analyze a part of it?

In order to reduce the volume of the sample chamber and simplify the synchronization algorithm, the method adopted in the present invention is to use a high-flow pump to pump a part of the exhaled gas into the elongated air chamber at a constant flow rate while exhaling. In this way, it can be ensured that the gas in different exhalation time periods is evenly distributed in the elongated air chamber.

3 Sample storage:

The gas to be analyzed is stored in the gas chamber, and the structure of the gas chamber is a long and thin pipeline, the purpose of which is to ensure that the flow of the gas in the gas chamber meets the plug flow condition during the sampling and analysis process.

4 Measurement analysis:

During the measurement and analysis, the pump drives the gas in the sample chamber to flow at a constant flow rate, and records the curve of the entire measurement process. If the gas flow ratio and time synchronization point during sampling and analysis are known, the measurement curve of the sensor can be compared with the expiratory flow rate. The measurement curves are correlated to make a relationship diagram between the sensor response value and the expiratory flow.

The greater the gas flow ratio between sampling and analysis, the lower the requirement for sensor response time. For example, if the ratio of the two is 10:1, a sensor with a response time of 10 seconds can be used to measure the change of NO concentration within 1 second of exhalation. . The selection of the gas flow rate used for sampling and measurement analysis depends on the response time of the sensor and the time resolution required for measurement. For breath NO analysis, the ratio of sampling to analysis flow rate can be controlled at 5 to 20 times.

5 Synchronization method:

During breath sampling, a part of the exhaled gas is stored in a slender pipeline at a high flow rate, and during analysis, the gas in the pipeline is passed into the sensor at a low flow rate for analysis and measurement. In order to make the two relatively independent There must be a synchronous time point associated with the process, and the selection of the synchronous point can be realized through the design of the gas path.

One way to select the synchronization point is to arrange the analysis pump at the front of the elongated air chamber, so that the gas at the end of breath sampling is first pumped into the sensor for analysis during measurement and analysis, and the starting point of this time corresponds to the end of breath sampling point in time.

Another way to select the synchronization point is to design a circular analysis gas circuit. At this time, the analysis pump is at the back end of the slender gas chamber. During the analysis and measurement, the analysis pump drives the gas in the gas chamber to enter the sensor for measurement, and then filter it with NO After the filter removes NO, it returns to the slender gas chamber. Since the gas flow in the gas chamber is a plug flow, when this part of the gas returns to the sensor, because the NO gas has been filtered by the NO filter, the response of the NO sensor will be fast. down to zero, and this time point corresponds to the time point at the end of the breath sampling.

To solve the above problems, by designing a suitable device, one-shot multi-parameter NO measurement can be realized. Although the analysis process of the measurement device will be different, the common points of the measurement and analysis process can be summarized as follows:

1) Expiration: Control exhalation to change according to the preset flow program, and record the curve of expiratory flow with time;

2) Sampling: collect the exhaled gas or part of it during the whole exhalation process in a slender tube air chamber;

3) Measurement: Pass the gas in the slender tube into the sensor at a gas flow rate that is compatible with the sensor response time for analysis and measurement, and record the sensor response curve over time;

4) Synchronization: Synchronize the exhalation and analysis process, and find the data correspondence between the expiratory flow rate and the measured value of exhaled NO;

5) Calculation: Calculate Jaw, Ca and FeNO ₅₀ according to the corresponding relationship between the corrected expiratory flow and exhaled NO.

Fig. 2 is a schematic diagram of a gas circuit structure of a breath multi-parameter exhaled nitric oxide measurement device, the gas circuit of the device is composed of a sampling module (100) and an analysis module (200), and it is characterized in that: the sampling module consists of A flow sensor (101), a flow regulator (201), and a solenoid valve (301) are connected in series, and the flow regulator (201) and the solenoid valve (301) are connected to the gas chamber (401) in the analysis module through a tee; The analysis module is sequentially composed of a gas chamber (401), a tee (501), an analysis pump (602), a gas humidity regulator (701), a NO sensor (801), a NO filter (901) and a three-way valve (302 ) to form a circulating air circuit; the pump (601) is connected to the air chamber (401) through a three-way (501), and a three-way valve (303) is connected in parallel between the NO filter (901) and the NO sensor (801).

Fig. 3 is a schematic diagram of another gas circuit structure of a breath multi-parameter exhaled nitric oxide measurement device, the gas circuit of the device is composed of a sampling module (100) and an analysis module (200), characterized in that: the sampling module It consists of a flow sensor (101), a flow regulator (201), and a solenoid valve (301) connected in series, and is connected to the solenoid valve (303) in the analysis module through a tee between the flow regulator (201) and the solenoid valve (301) ; The analysis module consists of solenoid valve (303), air chamber (401), three-way valve (501), analysis pump (602), gas humidity regulator (701), NO sensor (801), three-way valve (302) ) to form a circulating gas path; the pump (601) is connected to the air chamber (401) through a three-way valve (501), and the NO filter (901) is connected to the analysis gas path through a three-way valve (303).

The above two gas circuit structures can be used to measure the fast-changing exhaled NO concentration by using the electrochemical gas sensor with a slow reaction speed. In fact, professionals in the field can design more realization devices according to the principles of the present invention.

Description of drawings

Figure 1. Two-compartment model of alveolar and airway nitric oxide production and diffusion.

Figure 2. Schematic diagram of the composition of the exhaled nitric oxide measurement equipment with variable flow rate in one breath.

Fig. 3 is a schematic diagram of composition of breath variable flow rate exhaled nitric oxide measuring equipment.

Detailed ways

Application Example 1

Fig. 2 is the schematic diagram of gas circuit structure of a kind of device that realizes the method of the present invention, and described device is made of sampling module 100 and analysis module 200, and its structural characteristic is that described sampling module is made up of flow sensor 101, flow regulator 201, solenoid valve 301 in series, between the flow regulator 201 and the solenoid valve 301 is connected with the gas chamber 401 in the analysis module through a tee (not marked); the analysis module is sequentially composed of the gas chamber 401, the tee 501, the analysis pump 602, the gas Humidity regulator 701 (such as Nafion tube), NO sensor 801, NO filter 901 and three-way valve 302 constitute a circulating air circuit; pump 601 is connected to air chamber 401 through three-way 501, and NO filter 901 and NO sensor 801 are connected in parallel A three-way valve 303.

The process of using the device to measure breath variable flow rate exhalation is as follows:

1) Exhale:

Open the valve 301, after the subject inhales clean air, continue to exhale vigorously for 6-10 seconds, and adjust and control the expiratory flow through the program control flow regulator during the exhalation process, so that it changes with the preset flow rate program (such as linear decline), the flow sensor 101 measures the real-time measurement and record expiratory flow curve with time;

2) Sampling:

While exhaling, turn on the sampling pump 601 and analysis pump 602, adjust the positions of the three-way valves 302 and 303, and collect a part of the exhaled gas in the whole exhalation process in the slender tube air chamber 401. At this time, a part of the sampling gas Evacuated through the gas chamber 401, tee 501 and sampling pump 601; the other part is discharged through the gas chamber 401, tee 501, analysis pump 602, gas humidity regulator 701, NO sensor 801, three-way valve 303 and three-way valve 302 Empty, at this time the total gas flow rate is about 10ml/s, and the sampling time is 6~10 seconds;

3) Measure:

After the sampling is completed, close the valve 301 and the flow regulator 201, close the sampling pump 601, open the analysis pump 602, adjust the positions of the three-way valves 302 and 303 so that the gas flow direction becomes: gas chamber 401, three-way 501, analysis pump 602, Gas humidity regulator 701, NO sensor 801, NO filter 901, three-way valve 302 and gas chamber 401. At this time, the gas flow rate is about 1ml/s, and the entire analysis process takes about 120 seconds. Record the sensor response during the whole analysis process Time-varying curve; the steady-state current measured by the sensor after the gas passes through the NO filter 901 is the zero-point current;

4) Synchronization:

At the end of breath sampling, the exhaled gas is collected at the end of the elongated air chamber 401. During analysis, the pump 602 drives the gas to flow in the circulating air circuit (the flow of gas in the pipeline is plug flow), and the gas passes through the sensor After the measurement at 801 is filtered through the NO filter 901, the NO concentration drops to 0, and this part of the gas will return to the gas chamber 401, so that when the breath collected by the gas chamber 401 is completely analyzed, the response current of the sensor will occur sudden change (zero point current), the concentration corresponding to this time point is the concentration of exhaled NO at the end of breath sampling;

Since the sampled gas flow (about 10ml/s) and the analyzed gas flow (about 1ml/s) have been calibrated in advance, the exhaled gas per second can be measured on the sensor for 10 seconds, and the measurement time is magnified by 10 times. From the above The time at which the breath sampling ends is consistent with the inflection point time of the zero current during analysis, so that the data correspondence between the expiratory flow rate and the measured value of exhaled NO can be found;

5) Calculate:

Calculate Jaw, Ca and FeNO50 according to the corresponding relationship between the corrected expiratory flow and exhaled NO;

6) Self-calibration:

In order to realize the self-calibration of the sensor sensitivity, it is first necessary to collect NO gas with a uniform concentration in the gas chamber 401 (it is not necessary to know the specific concentration), which can be achieved by closing the valve 301, adjusting the three-way valves 302 and 303, and opening the pumps 601 and 602 directly. The air extraction sampling is realized. At this time, the air flow direction is divided into two paths, one path is: NO gas source, flow sensor 101, flow regulator 201, air chamber 401, tee 501, pump 601 and then emptied, and the other path is: NO gas Source, flow sensor 101, flow regulator 201, gas chamber 401, tee 501, pump 602, gas humidity regulator 701, NO sensor 801, three-way valve 303, 302 and then empty;

Adjust the positions of the three-way valves 302 and 303 during self-calibration, and the gas in the gas chamber 401 will return to the gas chamber through the three-way 501, the pump 602, the gas humidity regulator 701, the NO sensor 801, and the three-way valves 303 and 302 through the pump 602 401, in this way, through 2~3 cycles of measurement and analysis, the NO gas concentration in the gas chamber 401 can be directly calculated by the method disclosed in the patent ZL201210207872.6, and then the sensitivity to NO response can be calculated according to the response current of the NO sensor 801 during the cycle, Realize self-calibration.

Application Example 2

Fig. 3 is a schematic diagram of the gas path structure of another device for realizing the method of the present invention. The device is composed of a sampling module 100 and an analysis module 200, and its structural feature is that the sampling module consists of a flow sensor 101, a flow regulator 201, the electromagnetic valve 301 is connected in series, and the flow regulator 201 and the electromagnetic valve 301 are connected with the electromagnetic valve 303 in the analysis module through a three-way (not shown); the analysis module is sequentially composed of an electromagnetic valve 303, an air chamber 401, Pass 501, analysis pump 602, gas humidity regulator 701 (such as Nafion tube), NO sensor 801, and three-way valve 302 form a circulating gas circuit; the pump 601 is connected to the gas chamber 401 through the three-way 501, and the NO filter 901 is The valve 303 is connected to the analysis gas circuit.

The process of using the device to measure breath variable flow rate exhalation is as follows:

1) Exhale:

Open the valve 301, after the subject inhales clean air, continue to exhale vigorously for 6-10 seconds, and adjust and control the expiratory flow through the program control flow regulator during the exhalation process, so that it changes with the preset flow rate program (such as linear decline), the flow sensor 101 measures the real-time measurement and record expiratory flow curve with time;

2) Sampling:

While exhaling, turn on the sampling pump 601 and analysis pump 602, adjust the positions of the three-way valves 303 and 302, and collect a part of the exhaled gas during the whole process of exhalation in the slender tube air chamber 401. At this time, a part of the sampling gas The gas chamber 401, tee 501 and sampling pump 601 are emptied; the other part is evacuated through the gas chamber 401, tee 501, analysis pump 602, humidity regulator 701, NO sensor 801 and three-way valve 302. The flow rate is about 10ml/s, and the sampling time is 6~10 seconds;

3) Measure:

After the sampling is completed, close the valve 301 and the flow regulator 201, close the sampling valve 601, open the analysis pump 602, adjust the positions of the three-way valves 302 and 303 so that the gas flow direction becomes: air, NO filter 901, gas chamber 401, and three-way valve. Pass through 501, analysis pump 602, humidity regulator 701, NO sensor 801, three-way valve 302 and then empty. At this time, the gas flow rate is about 1ml/s, and the entire analysis process takes about 120 seconds. Record the sensor response during the whole analysis process Time-varying curve; the steady-state current measured by the sensor after the gas passes through the NO filter 901 is the zero-point current;

4) Synchronization:

At the end of breath sampling, the exhaled gas is collected at the end of the elongated air chamber 401. During analysis, the pump 602 drives the gas to flow in the air circuit (the flow of gas in the pipeline is plug flow), and the air passes through the NO After filtering by the filter 901, the NO concentration drops to 0, and this part of the gas will push the gas in the gas chamber 401 to move forward, so that when the breath collected by the gas chamber 401 is completely analyzed, the response current of the sensor will change suddenly ( Zero point current), the concentration corresponding to this time point is the concentration of exhaled NO at the end of breath sampling;

Since the sampled gas flow (about 10ml/s) and the analyzed gas flow (about 1ml/s) have been calibrated in advance, the exhaled gas per second can be measured on the sensor for 10 seconds, and the measurement time is magnified by 10 times. From the above The time at which the breath sampling ends is consistent with the inflection point time of the zero current during analysis, so that the data correspondence between the expiratory flow rate and the measured value of exhaled NO can be found;

5) Calculate:

Calculate Jaw, Ca and FeNO50 according to the corresponding relationship between the corrected expiratory flow and exhaled NO;

6) Self-calibration:

In order to realize the self-calibration of the sensor sensitivity, it is first necessary to collect NO gas with a uniform concentration in the gas chamber 401 (it is not necessary to know the specific concentration), which can be achieved by closing the valve 301, adjusting the three-way valves 302 and 303, and opening the pumps 601 and 602 directly. Pumping sampling is realized. At this time, the air flow direction is divided into two paths, one path is: NO gas source, flow sensor 101, flow regulator 201, tee 303, air chamber 401, tee 501, pump 601 and then evacuated, and the other path It is: NO gas source, flow sensor 101, flow regulator 201, three-way valve 303, gas chamber 401, three-way valve 501, pump 602, gas humidity adjustment device 701, NO sensor 901, three-way valve 302, and then empty;

Adjust the positions of the three-way valves 302 and 303 during self-calibration, and the gas in the gas chamber 401 is returned to the gas chamber through the three-way 501, the pump 602, the gas humidity regulator 701, the NO sensor 801, and the three-way valves 302 and 303 through the pump 602 401, in this way, through 2~3 cycles of measurement and analysis, the NO gas concentration in the gas chamber 401 can be directly calculated by the method disclosed in the patent ZL201210207872.6, and then the sensitivity to NO response can be calculated according to the response current of the NO sensor 801 during the cycle, Realize self-calibration.

Claims (2)

1. one breath multiparameter expiration nitric oxide measurement mechanism, be made up of sampling module (100) and analysis module (200), it is characterized in that: described sampling module is by flow sensor (101), flow regulator (201), solenoid valve (301) is composed in series, and is connected between flow regulator (201) and solenoid valve (301) by threeway with the air chamber (401) in analysis module; Described analysis module forms circulation gas circuit by air chamber (401), threeway (501), analysis pump (602), gas humidity regulator (701), NO sensor (801), NO filtrator (901) and T-valve (302) successively; Pump (601) is connected with air chamber (401) by threeway (501), a T-valve (303) in parallel between NO filtrator (901) with NO sensor (801).

2. one breath multiparameter expiration nitric oxide measurement mechanism, be made up of sampling module (100) and analysis module (200), it is characterized in that: described sampling module is by flow sensor (101), flow regulator (201), solenoid valve (301) is composed in series, and is connected between flow regulator (201) and solenoid valve (301) by threeway with the solenoid valve (303) in analysis module; Described analysis module forms circulation gas circuit by solenoid valve (303), air chamber (401), threeway (501), analysis pump (602), gas humidity regulator (701), NO sensor (801), T-valve (302) successively; Pump (601) is connected with air chamber (401) by threeway (501), and NO filtrator (901) is by T-valve (303) connect into analysis gas circuit.