CN100346742C - Method and system for non-invasive detecting intra-abdominal pressure - Google Patents

Abstract

The non-invasive detection method and system of intra-abdominal pressure belong to the field of medical measurement, and it is characterized in that it consists of a pressure sensor and a displacement sensor to form a pressure-displacement sensor combination, and the pressure sensor output generated when the external pressure of the abdomen is measured is measured by a data measurement and processing system Then calculate the value of intra-abdominal pressure according to the conversion formula of intra-abdominal pressure-external abdominal pressure obtained by data collected through clinical experiments and obtained by mathematical fitting method, which has the advantages of non-invasive and convenient clinical application; and put forward Corresponding hardware structure for non-invasive detection of intra-abdominal pressure.

Description

Non-invasive detection method and system for intra-abdominal pressure

technical field

The non-invasive detection method and system for intra-abdominal pressure belong to the field of medical measurement methods and devices, and are mainly used for indirect non-invasive measurement of intra-abdominal pressure.

Background technique

Abdominal compartment syndrome (ACS) is defined as a clinical syndrome formed by a series of pathophysiological changes caused by a sharp increase in intra-abdominal pressure. According to the speed of intra-abdominal pressure rise and the progress of the disease, it can be divided into acute ACS and chronic ACS (such as tumor, ascites, pregnancy). The clinically referred to ACS are all acute ACS, which often occur after trauma or abdominal surgery. When the intra-abdominal pressure increases sharply to a certain level, if measures are not taken in time, it will cause damage to multiple organs such as the lungs, kidneys, and heart, and even lead to multiple organ failure, shock and death.

At present, abdominal decompression is the only way to treat ACS, and the timing of operation has a great influence on the effect of abdominal decompression. Therefore, it is particularly important to determine the best operation time, which requires correct and timely understanding and tracking of ACS. condition. Since the size and change of intra-abdominal pressure (IAP) can accurately reflect the condition of ACS, it has been used clinically as an important indicator for judging the condition and deciding the time of operation.

At present, the measurement methods of intra-abdominal pressure can be divided into direct pressure measurement and indirect pressure measurement. The former is to directly place a tube in the abdominal cavity, and then connect a pressure sensor, or continuously monitor the abdominal pressure through an insufflation machine during laparoscopic surgery. Indirect manometry is to indirectly reflect intra-abdominal pressure by measuring inferior vena cava pressure, intragastric pressure and intravesical pressure.

Although it is still controversial whether bladder pressure accurately reflects intra-abdominal pressure, bladder pressure is the most commonly used in intra-abdominal pressure measurement as an objective indicator because cystometry is relatively accurate, simple and less invasive. This method was first proposed and described by Kron et al. The measurement method is very simple. The patient is placed in the supine position, the drainage tube is connected to the Foley catheter, 50ml of isotonic saline is injected into the bladder, and then a water pressure gauge is connected through a three-way connection to the pubic symphysis. is the zero plane, and the height of the water column is the intra-abdominal pressure.

In clinical practice, although the process of measuring bladder pressure is minimally invasive, it will still cause certain psychological and physical harm to the patient, and may even cause infection or acupuncture injury, causing adverse consequences. Therefore, it is necessary to study and seek an accurate and Non-invasive intra-abdominal pressure measurement method is very necessary, has important scientific significance and extensive practical value.

Contents of the invention

The purpose of the present invention is to provide a non-invasive detection method and device for intra-abdominal pressure, which calculates the value of intra-abdominal pressure from the measurement results of external pressure through the functional relationship between external pressure, displacement and intra-abdominal pressure, thereby Indirect non-invasive detection of intra-abdominal pressure can greatly reduce the burden on patients and doctors.

Considering that the pressure sensor and the displacement sensor are properly assembled, the proportional relationship between pressure and displacement can be realized. If the displacement is divided into stages, the pressure-displacement sensor device can be used to measure the external pressure under a certain displacement. There is a correlation between this data and the intra-abdominal pressure. If a functional relationship between the two is established, we can indirectly obtain the value of the intra-abdominal pressure from the functional relationship through the measured value of the external abdominal pressure, so as to truly realize the abdominal pressure. Non-invasive measurement of internal pressure. If the change of external abdominal pressure is measured under the condition of fixed displacement, or the change of displacement is measured under the condition of fixed external pressure, the development status of intra-abdominal pressure can be obtained, so as to ensure the real-time tracking of the patient's condition.

The method of the present invention is characterized in that: it contains the following steps successively:

(1) Input the sampling data of external abdominal pressure and the following external pressure-intra-abdominal pressure conversion formula into the computer:

y=ax+b

Among them, x is the external pressure of the abdomen, y is the intra-abdominal pressure, and a and b are undetermined coefficients respectively. For different types of pressure-displacement sensors, the specific values of a and b can be obtained in advance by the method of data fitting;

(2) Use a pressure-displacement sensor combination composed of a pressure sensor and a displacement sensor mechanically connected, and then measure the external abdominal pressure according to the following steps:

(2.1) Put the end of the slide bar of the pressure sensor close to the abdomen of the subject, that is, the initial values of displacement and external pressure are both zero, and then slowly push the slide bar so that the end presses the abdomen tightly to a certain value. fixed displacement;

(2.2) Under this displacement, the pressure sensor converts the external abdominal pressure at this time into a voltage value;

(3) The voltage value is input to a voltage amplifying circuit whose magnification is corresponding to the measuring range of the external abdominal pressure;

(4) The output signal of the voltage amplifying circuit is sent to the CPU after A/D conversion, and the corresponding intra-abdominal pressure is calculated and displayed; at the same time, it is also sent to the PC for storage through the USB acquisition card.

System of the present invention is characterized in that: it contains:

A pressure-displacement sensor, which is composed of a pressure sensor and a displacement sensor mechanically connected;

A voltage amplifying circuit, the input end of which is connected to the data output end of the above-mentioned pressure sensor;

A/D converter, its input end is connected with the output end of above-mentioned voltage amplifying circuit;

CPU, its signal input end is connected with the output end of above-mentioned A/D converter, and the signal output end of this CPU is connected with the signal input end of a display circuit;

The signal input end of the USB acquisition card is connected with the output end of the voltage amplifying circuit, and the output end of the USB acquisition card is connected with a PC.

This method will avoid the infection that may be caused by the invasive measurement, so that the clinician can realize the tracking and timely monitoring of the patient's condition without any trauma, and make the best judgment on the operation time, and the method is simple, convenient and more suitable in clinical application.

Description of drawings

Figure 1. Schematic diagram of the structure of the pressure-displacement sensor.

Figure 2. Schematic diagram of the use of pressure-displacement sensors:

A- The slide bar of the pressure sensor is close to the abdomen of the subject;

The slide bar of the B-pressure sensor squeezes the abdomen of the subject.

Figure 3. Calculation flow chart of the non-invasive detection method of intra-abdominal pressure.

Figure 4. Schematic block diagram of the circuit for the non-invasive detection system of intra-abdominal pressure.

Figure 5. Displacement-External Abdominal Pressure Curve of Example.

Figure 6. The external abdominal pressure-intra-abdominal pressure curve of the embodiment.

Detailed ways

Please see Figure 1: 6 is the pressure sensor, 1 is its sliding rod, 3 is the displacement sensor, 2 is the sliding head of 3, and 5 is the cylinder. The displacement sensor 3 is fixed on the inner wall of the cylinder 5 with the screw 4 , the sliding rod 1 and the sliding head 5 are wedged, and the pressure sensor 6 passes through the upper and lower ends of the cylinder 5 .

First use the slide bar 1 to cling to the subject’s abdomen, and then slowly advance the sliding head of the displacement sensor to a fixed value. During this advance process, the external pressure of the abdomen will change, which will cause the output voltage of the pressure sensor to change. The measured value is shown in Figure 5 the curve shown. Then by the system of the present invention, the curve shown in Fig. 6 is obtained, and output and displayed on the display circuit.

The following is an embodiment of the present invention: adopt the YH-4 type pressure sensor, adopt the sliding rheostat as the displacement sensor, obtain the external pressure-intra-abdominal pressure conversion formula coefficient a=110.0746, b=-3.4664 by data fitting, the measured The obtained intra-abdominal pressure is tabulated and compared with commonly used bladder pressure measurements as follows: age gender height (cm) weight(kg) Abdominal pressure (mv) Bladder pressure measurement (cm water column) Calculated value of intra-abdominal pressure (cm water column) error condition 58 male 173 53 100 7.5 7.54 0.04 peritoneal mucinous adenocarcinoma 38 male 168 55 68 4.0 4.02 0.02 traumatic brain injury 71 female 155 42.5 90 6.5 6.44 0.06 Obstructive jaundice, carcinoma of the head of the pancreas

Claims (1)

1. The intra-abdominal pressure non-invasive detection system is characterized in that it contains: The pressure-displacement sensor is composed of a pressure sensor and a displacement sensor mechanically connected, and converts abdominal pressure into displacement according to the following steps: First, put the end of the pressure sensor slide bar close to the subject's abdomen, that is, the initial values of displacement and external pressure are both zero, and then slowly push the slide bar so that the end presses the abdomen tightly to a fixed position. displacement; Secondly, under this displacement, the pressure sensor converts the external abdominal pressure at this time into a voltage value; Third, the voltage value is input to a voltage amplifying circuit with a magnification corresponding to the measurement range of the external abdominal pressure; the voltage amplifying circuit has an input terminal connected to the data output terminal of the above-mentioned pressure sensor; A/D converter, the input terminal is connected with the output terminal of the above-mentioned voltage amplifying circuit; CPU, the signal input end is connected with the output end of above-mentioned A/D converter, and the signal output end of this CPU is connected with the signal input end of a display circuit again; According to following formula y=ax+b, external abdominal pressure is converted into Intra-abdominal pressure, where x is external abdominal pressure, y is intra-abdominal pressure, and a and b are undetermined coefficients. For different types of pressure-displacement sensors, the specific values of a and b can be obtained in advance through data fitting methods; In the USB acquisition card, the signal input end is connected with the output end of the above-mentioned voltage amplifying circuit, and the output end of the USB acquisition card is connected with a PC.

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