CN1104475A - Pulse oximetry multi-wavelength optical measurement method and pulse oximetry monitor - Google Patents

Abstract

The invention relates to a medical device, which is especially suitable for measuring the oxygen saturation of human arterial blood. The invention adopts the dual-wavelength phase-separation modulation method to implement the optical measurement process. Under the condition of the same function and the same measurement accuracy, the cost of the pulse oximeter monitor is greatly reduced due to the low requirements for components and materials. It is suitable for Domestic promotion and use.

Description

The invention relates to a medical device.

Non-invasive, continuous and real-time measurement of human arterial blood oxygen saturation can be conveniently applied to critically ill and critical patient care, first aid, anesthesia and other occasions, and is an important means of modern surgery and monitoring processes. Amin as a miniator formed by the blood Vol35, NO.3, 1987) This kind of microelectronics integration technology, using hybrid optical sensor and its time-sharing drive, sampling and holding method and its corresponding pulse oximeter, its disadvantage is that the measurement sensitivity is low, when using a computer The A/D converter with high conversion accuracy must be used in the calculation, which is costly and difficult to popularize and use in China.

In view of the above-mentioned shortcomings in the prior art, the task of the present invention is to provide a pulse oximetry multi-wavelength optical measurement method with a dual-wavelength phase-separation modulation method and a pulse oximetry monitor.

The method of the present invention is to use two light beams of different wavelengths to measure the change of light absorption of the two wavelengths of light by blood at the same place in the superficial artery of the human body, and use the ratio of the two signals to directly follow the empirical formula SaO ₂ =AB obtained by the experiment. (I _λ2 , /I _λ1 ) to find blood oxygen saturation, and in order to implement this method, what the present invention adopts is to utilize the two-wavelength phase-splitting modulation method to realize the above-mentioned optical measurement process, that is, use the square wave generator 20 (Fig. 3) A square wave with a frequency of 1KHz and a duty ratio of 1:2 is generated, one path goes to the pulse type constant current driver 22, and the other path enters the pulse type constant current driver 23 through the inverter 21, and 22 and 23 are used to drive the sensor and mix the LED light source 2. The photoelectric receiver 3 and the pre-amplification circuit 7 on the sensor 11 transmit the mixed signal to the input terminal 1N (24) of the measurement circuit, and after being differentiated by two electronic switches that work synchronously with the driver, they are sent to the respective amplifiers 27 and 28 for amplification. The obtained two high-frequency modulation signals HO ₁ t HO ₂ are respectively used to identify sensor position errors, and then through the precision demodulation amplifiers 29 and 30, the low-frequency useful signals carried on the modulation signals, that is, volumetric pulse signals of different wavelengths, are respectively processed. Demodulate and amplify to restore the actual beat signals O ₁ and O ₂ .

The system block diagram of the human arterial oxygen saturation monitor system developed according to the above-mentioned method is shown in Figure 2, and it is made up of sensor 11, measurement amplifier circuit 12 and single-chip microcomputer 8098CPU (15), and described sensor 11 is shown in Figure 1, It is fixed by the shell 1 that upper and lower two halves constitute with axle 9, and both upper and lower halves can rotate around it. One end of the spring 6 attached to the shaft 9 is fixed to the upper half body, and the other end is fixed to the lower half body to realize the opening and closing movement of the two halves. The shell 1 is hollow or solid, and the inner wall of the shell after closing is round. Shape or polygon, inner layer pastes sponge 10. The LED tube 2 containing 2 tube cores is fixed on one half body, and the photoelectric converter 3 is fixed on the other half body, and their centers are opposite. Shaped rubber 5 is fixed. The pre-amplifier circuit 7 is fixed in the casing 1 and connected with the measuring circuit through the lead wire 8 .

The advantage of the present invention is that due to the dual-wavelength phase-separation modulation method, the requirements for sensors can be reduced. Therefore, domestic photoelectric devices can be directly used to design sensors. The requirements for components and materials are low, and the cost is low. It is suitable for popularization and use in China.

The accompanying drawings are as follows:

Attached Figure 1a Schematic diagram of sensor transmission structure

Accompanying drawing 1b is the B-B sectional view of Fig. 1a

Attachment 2 Human Arterial Oxygen Saturation Monitor System

Principle block diagram

Attached Figure 3 is the principle block diagram of the measurement method of the dual-wavelength phase-splitting modulation method.

Attached Figure 4 Measurement Circuit Diagram

In conjunction with accompanying drawing, the invention is further described as follows:

The principle of the monitor system is shown in Figure 2. The sensor 11 is connected to the measurement amplifier circuit 12 through the lead wire 8, and the modulation light source circuit 13 in the 12 generates a pulse signal with a frequency of 1KHz to drive the composite LED tube 2. The optical signal is sent to the input terminal 1N of the measuring amplifying circuit 14 through the photoelectric receiver 3 and the pre-amplification circuit 7, and the output signals are two high-frequency signals HO ₁ and HO ₂ , and the two volume pulse signals O ₁ and O ₂ are passed through respectively The single-chip 8098 CPU (15) contains four A/D converters for synchronous acquisition and storage. The single-chip microcomputer system includes basic components such as 64×240 dot-matrix liquid crystal display 16, 8 function keys 17, 16K bytes of EPROM (18) and 32K bytes of RAM (19). In this way, the judgment of the correctness of the two signals can be completed according to the principle of oximetry, the two signals are synchronously collected, stored, digitally filtered, automatically identified pulse peaks, automatically calculated SaO ₂ and pulse rate, real-time display waveform, stored 24-hour detection value, display 24-hour trend change graph, automatic connection alarm and other functions. The measurement circuit of the dual-wavelength phase-splitting modulation method is _shown in Figure 4, which corresponds to the schematic block diagram shown in Figure 3, where C1 and _C2 are used to drive the composite LED tube, and 1N is the input terminal of the sensor signal. HO ₁ and HO ₂ are high-frequency modulation signal outputs, which are used to judge whether the sensor position is correct or not and to correct the measurement results. O ₁ and O ₂ are useful low-frequency signals, namely volume pulse waves, which are input into the computer.

Claims (2)

1, a kind of pulse blood oxygen multi-wavelength optical measuring method adopts two light beams of different wavelengths, and the same place of spattering the table tremulous pulse at the human body body measures the variation of two wavelength light through the blood light absorption, and with two signal ratios directly by testing the empirical equation SaO tried to achieve ₂=A-B (I λ ₂/ I λ ₁) ask blood oxygen saturation, it is characterized by and adopt dual wavelength phase-splitting modulation method to implement above-mentioned optical measurement process, promptly producing frequency with square-wave generator (20) is 1KH ₂, dutycycle is 1: 2 square wave, one the road to pulsed constant-flow driver (22), another road enters pulsed constant-flow driver (23) through phase inverter (21), (22) and (23) be used for driving sensor mixing led light source (2), photelectric receiver (3) and pre-arcing road (7) on the pick off (11) are transferred to measuring circuit input 1N (24) with mixed signal, and through sending into amplifier (27) and (28) middle amplification separately, two high-frequency modulation signal HO that obtain after two electrical switches differentiations that work asynchronously with driver ₁And HO ₂Be respectively applied for the identification sensor positional fault, and the low frequency useful signal that carries on respectively with modulation signal through accurate demodulator amplifier (29) and (30) again, the volume pulsation signal of seal different wave length is separated to be in harmonious proportion and is amplified, and restores actual pulse signal O ₁And O ₂

2, human body artery ohmeda 3700 pulse oxmeter according to the described method of claim 1, it is by pick off (11), measure amplifying circuit (12), single-chip microcomputer 8098CPU(15) constitutes, it is fixing with axle (9) by the shell (1) that two halfbodies up and down constitute to it is characterized by described pick off, two halfbodies all can rotate around it up and down, spring (6) one ends that are closely attached on axle (9) are fixed in upper semi-body, the other end is fixed in lower semi-body, to realize opening and closing up motion of two halfbodies, shell 1 is hollow or solid, rounded or the polygon of outer casing inner wall after closing up, interior laminating sponge (10), the LED tube core (2) that includes the tribute of 2 pipes is fixed on the halfbody, optical-electrical converter (3) is fixed on another halfbody, their center is relative, on LED pipe (2) and optical-electrical converter (3) scattering sheet (4) is housed, and is fixing with rubber turn (5), pre-arcing road (7) is fixed in the housing (1), connects with measuring circuit by lead-in wire (8).

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