Method for judging the reverse connection of a flow sensor and a respiratory mechanics measuring module used therein

Abstract

A method for judging the reverse connection of a flow sensor comprises the steps of: collecting a time sequence of pressure intensity x1, x2, x3 and x4 at four consecutive sampling points of time and the flow value S corresponding to that time sequence as basis for judgment; calculating three variables dx1=x1−x2, dx2=x2−x3 and dx3=x3−x4; judging a reverse connection of the flow sensor and giving an alarm signal when any one of the two instances appears: 1) x1, x2 and x3 are all smaller than zero and x1 and x3 are equal to or greater than x2, and flow value S is smaller than a predetermined first threshold value f1; 2) dx1, dx2 and dx3 are all greater than zero and dx1 and dx3 are smaller than or equal to dx2, and flow value S is greater than a predetermined second threshold value f2.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a structural schematic illustration of a flow sensor;

FIG. 2 is a first-level schematic diagram illustrating the structure of a respiratory mechanics module system according to the present invention;

FIG. 3 is a second-level schematic diagram illustrating the structure of a respiratory mechanics module system according to the present invention;

FIG. 4 is a schematic illustration of the normal waveforms of pressure intensity and flow under an autonomous respiration state;

FIG. 5 is a schematic illustration of the waveforms of pressure intensity and flow under an autonomous respiration state where the flow sensor is reversedly connected;

FIG. 6 is a schematic illustration of the normal waveforms of pressure intensity and flow under a mechanical ventilation state; and

FIG. 7 is a schematic illustration of the waveforms of pressure intensity and flow under a mechanical ventilation state where the flow sensor is reversedly connected.

Claims

1. A method for judging the reverse connection of a flow sensor in a respiratory mechanics measurement, comprising the following steps of: a. connecting the flow sensor to a respiratory mechanics measuring module;b. sampling consecutively airway pressures and flows of a respiratory gas flowing between a patient and an anaesthetic machine;c. judging that the flow sensor is reversedly connected and sending an alarm signal indicating the reverse connection of the flow sensor to a main controller when any one of the following two instances appears:1) when the airway pressure decreases to the lowest point, the flow has a negative value while the patient is inhaling;2) around the time when the pressure intensity decreases the fastest, the flow has a positive value.

2. The method for judging the reverse connection of a flow sensor according to claim 1, wherein the process of sampling consecutively the airway pressures and flows of the respiratory gas flowing between the patient and the anesthetic machine as stated in step b comprises the following steps of: collecting a time sequence of the pressure intensity x1, x2, x3 and x4respectively corresponding to four consecutive sampling points of time within an arbitrary time interval and the flow value S corresponding to that time interval as the basis for judgment, and calculating three pressure difference variables using the equations dx1=x1−x2, dx2=x2−x3 and dx3=x3−x4; and wherein the two instances as stated in step c, the occurrence of any one of which indicates the reverse connection of the flow sensor, are as follows:1) x1, x2 and x3 are all smaller than zero and meanwhile x1 and x3 are equal to or greater than x2, and the flow value S is smaller than a predetermined first threshold value f1; and2) dx1, dx2 and dx3 are all greater than zero and meanwhile dx1 and dx3are smaller than or equal to dx2, and the flow value S is greater than a predetermined second threshold value f2.

3. The method for judging the reverse connection of a flow sensor according to claim 2, wherein the first threshold value f1 is set at −2 liters/minute and the second threshold value f2 is set at 3 liters/minute, both of which are used for eliminating misjudgment caused by tiny and weak interference.

4. A respiratory mechanics measuring module, comprising a flow sensor (1), a differential pressure sensor (2) and a sampled signal processing circuit (3) which are connected in series, the sampled signal processing circuit (3) transferring the calculation results to a main controller (4), and further comprising a flow sensor reverse connection judging module (5) and an alarm (6), wherein the flow sensor reverse connection judging module (5) judges whether the flow sensor is reversedly connected based on the output signals of the differential pressure sensor (2), and the alarm (6) sends a prompting signal indicating the flow sensor reverse connection to the main controller (4) when the flow sensor reverse connection judging module (5) judges that the flow sensor is reversedly connected.

5. The respiratory mechanics measuring module according to claim 4, wherein the sampled signal processing circuit (3) comprises an amplification circuit connected to the signal output end of the differential pressure sensor (2), an analog-to-digital converter, a gain controller and a single chip processor which is in bi-directional communication with the analog-to-digital converter and the main controller (4), respectively.

6. The respiratory mechanics measuring module according to claim 5, wherein the flow sensor reverse connection judging module (5) is an algorithm program solidified in the single chip processor.

7. A method for judging the reverse connection of a flow sensor in respiratory mechanics measurement, comprising the following steps of: a. providing a respiratory mechanics measuring module and connecting thereto the flow sensor to be judged, the respiratory mechanics measuring module comprising a differential pressure sensor, a sampled signal processing circuit and an alarm;b. measuring four pressure intensity values x1, x2, x3 and x4 of a respiratory gas in an airway corresponding to four consecutive sampling points of time within an arbitrary time interval and the flow value S of that time interval using the differential pressure sensor and the flow sensor, and calculating three pressure difference variables in the sampled signal processing circuit using the equations dx1=x1−x2, dx2=x2−x3 and dx3=x3−x4;c. sending an alarm signal indicating the reverse connection of the flow sensor with the alarm, if x1, x2 and x3 are all smaller than zero and meanwhile x1 and x3 are equal to or greater than x2, and the flow value S is smaller than a predetermined first threshold value f1; or if dx1, dx2 and dx3are all greater than zero and meanwhile dx1 and dx3 are smaller than or equal to dx2, and the flow value S is greater than a predetermined second threshold value f2.

8. The method for judging the reverse connection of a flow sensor according to claim 7, wherein the sampled signal processing circuit comprises an amplification circuit connected to the signal output end of the differential pressure sensor, an analog-to-digital converter, a gain controller and a single chip processor.

9. The method for judging the reverse connection of a flow sensor according to claim 8, wherein an algorithm program used for judging the reverse connection of the flow sensor is solidified in the single chip processor.