CN1299103C - Sampling device for monitoring and surveying end-expiratoxy carbon dioxide - Google Patents

Abstract

The invention relates to a sampling gas chamber device for monitoring and measuring end-tidal carbon dioxide, which belongs to the technical field of biomedical engineering. Sampling device of the present invention comprises the sampling gas chamber (1) that is made of cylinder and hemisphere, and the gas that is placed on the hemisphere of sampling gas chamber (1) is introduced into air inlet (2) and conical air inlet grid ( 3), the parabolic reflector (4) connected to the conical air intake grid (3), the infrared light source (5), optical filter (6), and infrared detection placed on the cylinder end face of the sampling gas chamber (1) Device (7) and air outlet (8). The invention can greatly improve the real-time performance and stability of measurement, and improve the accuracy of monitoring; it has the advantages of simple structure, long service life, wide application range, high cost performance and the like.

Description

Sampling device for capnography measurement

Technical field:

The invention relates to a sampling device for monitoring and measuring end-tidal carbon dioxide, belonging to the technical field of biomedical engineering.

Background technique:

Monitoring the volume fraction of carbon dioxide in a patient's breath is a non-invasive monitoring method. It can not only monitor the patient's ventilation function but also reflect its circulatory function and pulmonary blood flow. It has gradually become a common clinical monitoring method. Its clinical significance includes: monitoring the ventilation function of patients with respiratory insufficiency caused by various reasons; monitoring changes in circulatory function and carbon dioxide production in the body; understanding changes in alveolar dead space and pulmonary blood flow; Adjust the ventilation according to the monitoring to avoid hypercapnia or hypocarbia caused by hypoventilation or overventilation; detect the mechanical failure of the ventilator in time.

The end-tidal carbon dioxide monitoring device uses the principle of non-diffused infrared (NDIR) absorption, and the data is collected and processed by the microcontroller, which realizes the non-invasive, real-time and continuous monitoring of the _CO2 volume fraction in the respiratory airway. Most gases have unique infrared absorption characteristics in the wavelength range of 2 to 14 μm, which enables definite identification and quantitative detection of gases. _CO2 has a strong absorption peak at a wavelength of 4.26μm. When the sensor emits infrared rays and passes through the middle measurement sampling gas chamber, the infrared detector will absorb part of the infrared energy when it receives the _CO2 gas flowing through the sampling gas chamber. The absorption law of the infrared ray signal satisfies the Lambert-Beer (Lambert-Beer) absorption law. After processing by the microcomputer, it can display the PetCO ₂ waveform and measurement value.

The signal acquisition of end-tidal carbon dioxide monitoring is completed through the sampling air chamber installed on the air circuit. The sampling air chamber forms a cavity on the air circuit. The airflow enters from one end and flows out from the other end. Infrared transmitting and receiving probes are respectively installed at both ends of the air chamber to transmit and receive infrared signals. Or the probe is at the same end, and the infrared signal is received through the reflection of the gas chamber wall. In order to ensure the real-time performance, reliability and stability of signal collection, the volume of the gas chamber should not be too large or too small; the gas chamber should be installed on a bracket with constant temperature function to reduce the influence of temperature on the received signal.

After literature search, no public reports related to the end-tidal carbon dioxide monitoring measurement sampling gas chamber device identical to the technical solution of the present invention have been found.

Invention content:

The purpose of the present invention is to provide a sampling device for end-tidal carbon dioxide monitoring and measurement that can not only satisfy real-time performance and reliability, but also take into account simple installation of an air chamber, small volume and stability.

The sampling device for end-tidal carbon dioxide monitoring and measurement of the present invention comprises a sampling chamber (1) composed of a cylinder and a hemisphere, and the gas on the hemisphere of the sampling chamber (1) is introduced into an air inlet (2) and The conical air intake bar (3), the parabolic reflector (4) connected with the conical air intake bar (3), the infrared light source (5) and the optical filter placed on the end face of the cylinder of the sampling gas chamber (1) (6), infrared detector (7) and gas outlet (8). When working, the gas is introduced into the gas sampling chamber (1) by the gas inlet (2), and the gas flow passes through the narrow passage between the inlet and the conical inlet grid (3), forming a vortex and pushing the surrounding The function of gas accelerates the exchange of airflow in the gas chamber. The infrared light emitted by the infrared light source (5) is reflected by the parabolic reflector (4), which increases the intensity of the signal. The reflected light is focused on the narrow-band optical filter (6). The peak wavelength is 4.26 μm, which is received by the infrared detector (7), and the gas outlet (8) leads the gas to the external nozzle tube.

The invention can greatly improve the real-time performance and stability of measurement, and improve the accuracy of monitoring; it has the advantages of simple structure, long service life, wide application range, high cost performance and the like.

Description of drawings:

Accompanying drawing 1 is the structural representation of the present invention.

Figure 2 CO ₂ infrared absorption spectrum.

Detailed ways:

Sampling gas chamber (1) of the present invention is processed with superhard aluminum alloy, length L=52mm, internal diameter D=26mm, internal polishing, other parts are assembled on the sampling gas chamber (1) according to the position shown in accompanying drawing 1 respectively.

When working, the gas to be measured is first introduced into the air inlet (2) through the external nozzle tube, and after the gas enters the air chamber (1), the airflow flows from the air inlet (2) and the conical air inlet grid (3) The narrow channel between them passes through, forming a vortex and pushing the surrounding gas, which accelerates the exchange of air in the gas chamber. The infrared light emitted by the infrared light source (5) is reflected by the parabolic reflector (4), which increases the strength of the signal. The light is focused on the filter (6), received by the infrared detector (7), and the gas outlet (8) leads the gas to the external nozzle tube. The entire measuring gas chamber is placed horizontally on a thermostatic bracket.

The use of the present invention shows that the real-time performance and stability of measurement can be greatly improved, and the accuracy of monitoring can be improved.

Claims (1)

1. A sampling device for end-tidal carbon dioxide monitoring and measurement, characterized in that the sampling device comprises a sampling chamber (1) made of a cylinder and a hemisphere, the gas placed on the hemisphere of the sampling chamber (1) Introduce the air inlet (2) and the conical air intake grid (3), and the parabolic reflector (4) connected with the conical air intake grid (3), placed on the end surface of the cylinder of the sampling gas chamber (1) An infrared light source (5), an optical filter (6), an infrared detector (7) and an air outlet (8).