Breathing machine pipeline detection method

Abstract

The invention discloses a breathing machine pipeline detection method. The method comprises the steps that a model is established according to parameters and corresponding equivalent relations; connecting a breathing machine pipeline; air is supplied to the pipeline at a constant flow QV until the airway pressure in the pipeline rises to 10cm H2O, and the moment t1 is recorded; if the airway pressure cannot rise to 10cm H2O within 10s, the detection is ended; otherwise, continuously detecting; and supplying air at a constant flow until the pressure of the air passage in the pipeline is increased to 40cm H2O. Linear system analysis and modeling are carried out on the pipeline, parameters in the model are estimated through flow measured by the flow sensor and pressure values measured by the pressure sensor, the compliance, resistance and leakage quantity parameters of the pipeline are conveniently and accurately obtained, operation is convenient, and the reliability of the pipeline is improved. And the test efficiency and the accuracy of a measurement result are greatly improved.

Description

Technical Field

[0001] The invention belongs to the technical field of medical ventilators, and in particular relates to a ventilator pipeline detection method. Background Art

[0002] The ventilator is an important life support device used in the ICU and other departments of the hospital. It is used to treat patients with respiratory dysfunction. The ventilator delivers gas to the patient according to the mode and parameters set by the user. The ventilator is connected to the patient through a pipeline, so the state of the pipeline will directly affect the ventilation effect.

[0003] The most critical parameters related to ventilation are compliance, resistance, and leakage. These parameters will affect the ventilation control and parameter calculation of the ventilator. For example, if the flow sensor is located upstream of the inhalation branch of the pipeline, the influence of pipeline compliance needs to be considered when calculating the tidal volume; when performing operations related to airway pressure control or judgment, pipeline resistance is a factor that needs to be considered; and when calculating all flow-related parameters, pipeline leakage is an important influencing factor.

[0004] Therefore, obtaining these key pipeline parameters has become a prerequisite for ensuring high-quality and normal ventilation of the ventilator. Although standard pipelines are marked with parameters such as compliance and resistance when leaving the factory, these parameters may change after long-term use. In addition, during the normal use of the ventilator, in addition to the breathing pipeline, it may be necessary to connect components such as humidifiers, which will also affect the parameters of the pipeline. This requires the ventilator to be able to dynamically detect the pipeline to determine the values ​​of its key parameters.

[0005] The traditional method of pipeline detection is to manually measure the pipeline parameters. For example, compliance and leakage can be obtained by filling a certain volume of gas into a closed pipeline and observing the pressure changes in the pipeline; and resistance can be obtained by inputting a constant flow of gas into an open pipeline and observing the pressure difference between the inhalation and exhalation ends of the pipeline. The disadvantages of these pipeline leakage methods are that they are inconvenient to operate and have poor measurement accuracy.

[0006] With the development of technology, some methods for automatically detecting pipeline parameters have emerged one after another. However, most of these methods only use MCU (microcontroller) to process and automate the above manual measurement methods through software. There are still problems such as low test efficiency and poor measurement accuracy. Summary of the invention

[0007] The purpose of the present invention is to provide a ventilator pipeline detection method to solve the problems of inconvenient operation and poor measurement accuracy of the traditional pipeline detection method proposed in the above background technology.

[0008] To achieve the above object, the present invention provides the following technical solution: a ventilator circuit detection method, comprising the following steps: Step 1: Establish a respiratory mechanics linear model of the pipeline based on the known equivalent relationship between the resistance and compliance in the respiratory airway and the resistance and capacitance in the circuit; Step 2: Connect the ventilator tube and connect the Y-piece port of the breathing tube to the plug for sealing; Step 3: Close the exhalation valve and keep the flow rate Q constant. V Open the inhalation valve to supply air to the ventilator pipeline until the airway pressure in the pipeline rises to P1, and record the time t1 at this time. Under normal circumstances, the constant flow rate Q is preset. V The time from air supply until the airway pressure rises to P1 is T1, and t1 is compared with T1; If t1>T1, it is considered that the leakage is too large, the pipeline test fails, and the test ends; On the contrary, if t1≤T1, continue to detect; Step 4: Continue with constant flow rate Q V Supply air until the airway pressure in the pipeline rises to P2. During this process, set a time interval T and record the airway pressure P and air flow Q during the rising process at each time interval T. V , and the time t2 when the airway pressure reaches P2; Step 5: Use the flow sensor to measure the air flow Q V The airway pressure P measured by the pressure sensor is used to estimate the parameters in the respiratory mechanics linear model of the circuit to obtain the circuit compliance C T 、Pipeline leakage air resistance R L And the pipeline resistance R T parameter.

[0009] Preferably, in step 3, Q V is 5L / min, P1 is 10cmH2O, and T1 is 10s.

[0010] Preferably, in step 4, P2 is 40 cmH2O and T is 10 ms.

[0011] Preferably, the step five comprises the following steps: Step 5.1: The following formula is obtained through the respiratory mechanics linear model of the pipeline: Where t is the comparison time, u is the time variable in the integral formula; P(t) is the airway pressure at time t, Q V is the air flow rate, Q L is the pipeline leakage flow, C T is the pipeline compliance, RL is the pipeline leakage resistance, R T is the pipeline resistance; is the pipeline storage flow at time t, is the pipeline leakage flow at time t, is the air flow rate at time u, is the pipeline leakage flow at time u, is the integral symbol, indicating the integrand; Step 5.2: After discretization, the Least Square Fitting method is used to obtain the following formula: in: In formulas (4)-(13), K1, K2, K3, and K4 represent intermediate variables 1, 2, 3, and 4, respectively; n is a natural number, representing the nth sampling value; S1 and S2 represent intermediate variables 5 and 6, respectively; Δt represents the sampling time; P(n) represents the airway pressure at the nth sampling point; Q V (n) represents the air flow rate at the nth sampling point; Step 5.3, Cramer's rule can be used to obtain: (14); (15); (16); (17); (18); Therefore, the pipeline parameters are: In formulas (14)-(25), D, D1, D2, D3, and D4 represent intermediate variable seven, intermediate variable eight, intermediate variable nine, intermediate variable ten, and intermediate variable eleven, respectively.

[0012] Compared with the prior art, the advantages and benefits of the present invention are: The present invention performs linear system analysis and modeling on the pipeline, and estimates the parameters in the model using the flow rate measured by the flow sensor and the pressure value measured by the pressure sensor. In this way, the compliance, resistance and leakage parameters of the pipeline can be easily and accurately obtained. This method is not only easy to operate, but also greatly improves the test efficiency and the accuracy of the measurement results. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 is a linear model diagram of respiratory mechanics of the pipeline of the present invention; Figure 2 This is a pipeline detection flow chart of the present invention. DETAILED DESCRIPTION

[0014] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0015] See also Figure 1-2 The present invention provides a technical solution: a ventilator circuit detection method, comprising the following steps: Step 1: Establish a respiratory mechanics linear model of the pipeline based on the known equivalent relationship between the resistance and compliance in the respiratory airway and the resistance and capacitance in the circuit; Step 2: Connect the ventilator tube and connect the Y-piece port of the breathing tube to the plug for sealing; Step 3: Close the exhalation valve and keep the flow rate Q constant. V Open the inhalation valve to supply air to the ventilator pipeline until the airway pressure in the pipeline rises to P1, and record the time t1 at this time. Under normal circumstances, the constant flow rate Q is preset. V The time from air supply until the airway pressure rises to P1 is T1, and t1 is compared with T1; If t1>T1, it is considered that the leakage is too large, the pipeline test fails, and the test ends; On the contrary, if t1≤T1, continue to detect; Furthermore, in step 3, Q V is 5L / min, P1 is 10cmH2O, and T1 is 10s.

[0016] Step 4: Continue with constant flow rate Q V Supply air until the airway pressure in the pipeline rises to P2. During this process, set a time interval T and record the airway pressure P and air flow Q during the rising process at each time interval T. V , and the time t2 when the airway pressure reaches P2; Furthermore, in step 4, P2 is 40 cmH2O and T is 10 ms.

[0017] Step 5: Use the flow sensor to measure the air flow Q V The airway pressure P measured by the pressure sensor is used to estimate the parameters in the respiratory mechanics linear model of the circuit to obtain the circuit compliance C T 、Pipeline leakage air resistance R L And the pipeline resistance R T parameter.

[0018] The present invention performs linear system analysis and modeling on the pipeline, and estimates the parameters in the model using the flow rate measured by the flow sensor and the pressure value measured by the pressure sensor. In this way, the compliance, resistance and leakage parameters of the pipeline can be easily and accurately obtained. This method is not only easy to operate, but also greatly improves the test efficiency and the accuracy of the measurement results.

[0019] Furthermore, step five includes the following steps: Step 5.1: The following formula is obtained through the respiratory mechanics linear model of the pipeline: Where t is the comparison time, u is the time variable in the integral formula; P(t) is the airway pressure at time t, Q V is the air flow rate, Q L is the pipeline leakage flow, C T is the pipeline compliance, R L is the pipeline leakage resistance, R T is the pipeline resistance; is the pipeline storage flow at time t, is the pipeline leakage flow at time t, is the air flow rate at time u, is the pipeline leakage flow at time u, is the integral symbol, indicating the integrand; Step 5.2: After discretization, the Least Square Fitting method is used to obtain the following formula: in: In formulas (4)-(13), K1, K2, K3, and K4 represent intermediate variables 1, 2, 3, and 4, respectively; n is a natural number, representing the nth sampling value; S1 and S2 represent intermediate variables 5 and 6, respectively; Δt represents the sampling time; P(n) represents the airway pressure at the nth sampling point; Q V (n) represents the air flow rate at the nth sampling point; Step 5.3, Cramer's rule can be used to obtain: (14); (15); (16); (17); (18); Therefore, the pipeline parameters are: In formulas (14)-(25), D, D1, D2, D3, and D4 represent intermediate variable seven, intermediate variable eight, intermediate variable nine, intermediate variable ten, and intermediate variable eleven, respectively.

[0020] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A ventilator pipeline detection method, characterized in that: The following steps are involved: Step 1: Establish a respiratory mechanics linear model of the pipeline based on the known equivalent relationship between the resistance and compliance in the respiratory airway and the resistance and capacitance in the circuit; Step 2: Connect the ventilator tube and connect the Y-piece port of the breathing tube to the plug for sealing; Step 3: Close the exhalation valve and keep the flow rate Q constant. V Open the inhalation valve to supply air to the ventilator pipeline until the airway pressure in the pipeline rises to P1, and record the time t1 at this time. Under normal circumstances, the constant flow rate Q is preset. V The time from air supply until the airway pressure rises to P1 is T1, and t1 is compared with T1; If t1>T1, it is considered that the leakage is too large, the pipeline test fails, and the test ends; On the contrary, if t1≤T1, continue to detect; Step 4: Continue with constant flow rate Q V Supply air until the airway pressure in the pipeline rises to P2. During this process, set a time interval T and record the airway pressure P and air flow Q during the rising process at each time interval T. V , and the time t2 when the airway pressure reaches P2; Step 5: Use the flow sensor to measure the air flow Q V The airway pressure P measured by the pressure sensor is used to estimate the parameters in the respiratory mechanics linear model of the circuit to obtain the circuit compliance C T 、Pipeline leakage air resistance R L And the pipeline resistance R T parameter.

2. A ventilator pipeline detection method according to claim 1, characterized in that: Step 3 Q V is 5L / min, P1 is 10cmH2O, and T1 is 10s.

3. A ventilator pipeline detection method according to claim 1, characterized in that: In step 4, P2 is 40 cmH2O and T is 10 ms.

4. A ventilator circuit detection method according to claim 1, characterized in that: Step five includes the following steps: Step 5.1: The following formula is obtained through the respiratory mechanics linear model of the pipeline: Where t is the comparison time, u is the time variable in the integral formula; P(t) is the airway pressure at time t, Q V is the air flow rate, Q L is the pipeline leakage flow, C T is the pipeline compliance, R L is the pipeline leakage resistance, R T is the pipeline resistance; is the pipeline storage flow at time t, is the pipeline leakage flow at time t, is the air flow rate at time u, is the pipeline leakage flow at time u, is the integral symbol, indicating the integrand; Step 5.2: After discretization, the Least Square Fitting method is used to obtain the following formula: in: In formulas (4)-(13), K1, K2, K3, and K4 represent intermediate variables 1, 2, 3, and 4, respectively; n is a natural number, representing the nth sampling value; S1 and S2 represent intermediate variables 5 and 6, respectively; Δt represents the sampling time; P(n) represents the airway pressure at the nth sampling point; Q V (n) represents the air flow rate at the nth sampling point, Step 5.3, Cramer's rule can be used to obtain: （14）； （15）； （16）； （17）； （18）； Therefore, the pipeline parameters are: In formulas (14)-(25), D, D1, D2, D3, and D4 represent intermediate variable seven, intermediate variable eight, intermediate variable nine, intermediate variable ten, and intermediate variable eleven, respectively.

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