CN1542434A - Tissue blood-oxygen parameter detection method capable of amending outer layer tissue influence - Google Patents

Abstract

The blood oxygen parameter measuring method capable of correcting the influence of outer tissue belongs to the field of biomedicine engineering. The present invention features that for different measured targets and different biological tissues, proper detection distance is selected in detecting oxidized hemoglubin variation and reduced hemoglubin variation; sensor design, detection steps, algorithm and system design are proposed in considering the influence of outer tissue. The sensor consists of three LED's and one photoelectric detector; and the whole test system consists of sensor, pre-amplifier, A/D converter, embedded micro controller, communication circuit, power supply, LCD and touch screen. The present invention has the advantages of high detectioin sensitivity and simple detection system structure.

Description

Tissue blood-oxygen parameter detection method capable of amending outer layer tissue influence

Technical field:

Tissue blood-oxygen parameter detection method capable of amending outer layer tissue influence belongs to biomedical engineering field.

Background technology:

With the variable quantity that closes oxygen (and reduction) haemoglobin in the Near-infrared Double wave spectrum method detection of biological tissue, this itself is domestic and international proven technique.But, therefore greatly influenced the precision that detects owing to there is the influence (outer tissue is meant the tissue that covers outside the tissue to be measured, and as the covering of fat to muscle, scalp, skull and cerebrospinal fluid are to the covering of brain cortex) of outer tissue.To this problem, the external not document of relevant patent, (its publication number is respectively CN1333001A to domestic disclosed three relevant patents, CN1331953A, CN1365649A) all be to adopt point-blank that arrange and the methods not equidistant a plurality of photosensitive two newspaper pipes of light source, think only relevant with outer tissue from light source signal nearby, and with the remote signal of distance light in both comprised the information of outer tissue and deep layer tissue to be measured, and the method for subtracting each other with the light intensity that two detecting devices receive is to eliminate the influence of outer tissue, as shown in Figure 1, wherein a is a light source, b is a detecting device, and c is probe, and d is a detecting device, e is a deep layer tissue to be measured, and f is an outer tissue.This way reduces system architecture complexity, the weak sensitivity of signal.The present invention then takes an other thinking.Promptly be that thickness with outer tissue is parameter, derive the correction coefficient that test structure is revised.To reach the purpose of correction.

Summary of the invention:

The object of the present invention is to provide the simple in structure of a kind of tissue oxygenation detection method of revising outer tissue influence and detection system, accuracy of detection is also higher.

The invention is characterized in: it uses three each self energy difference emission wavelengths to be λ ₁Ruddiness and wavelength be λ ₂The luminotron of infrared light form sensor with the photoelectric receiving tube that is positioned at a side, the centre distance d of three luminous light and photelectric receiver is at least 30mm, 40mm and 50mm, during detection according to the type of outer tissue therefrom choose have can the light emitting diode of centre distance, and only order this lumination of light emitting diode, be respectively λ according to detected wavelength ₁, λ ₂Optical density OD ^{λ 1}I=1,2, calculate respectively two neighbouring samples constantly close the change amount Δ CHbO2 oxygen hemoglobin concentration and reduced hemoglobin concentration, Δ CHb, consider the influence of outer layer thickness again, divided by less than 1 correction factor, just can obtain revising the Δ CHbO2 behind the outer tissue thickness effect, the value of Δ CHb to the Δ CHbO2 that is calculated, Δ CHb; Above-described method has following steps successively:

(1), measures outer tissue thickness with ultrasonic method and select a fixed light emitting diode with photoelectric receiving tube apart from d according to the thickness of outer tissue according to the object of test and the position of test;

(2) detection optical density value under the centre distance of the photoelectric receiving tube of selected luminotron ${\mathrm{OD}}^{{\mathrm{\λ}}_I}i=\mathrm{1,2};$

Wherein, I _{Go into}Be light source power, I _{Go out}Be that incident light passes through after biological tissue's scattering the luminous power that photoelectric receiving tube is received;

(3) detect the blood oxygen condition in time in the change procedure, two neighbouring sample optical density OD at interval ^{λ 1}Difference OD _k ^{λ i}

${\mathrm{\ΔOD}}_k^{\mathrm{\λi}}={\mathrm{OD}}_{t+1}^{\mathrm{\λi}}-{\mathrm{OD}}_t^{\mathrm{\λi}}$

Wherein, OD _t ^{λ i}And OD _T+1 ^{λ i}Being respectively wavelength is λ _iThe time, at t constantly and subsequent t+1 optical density constantly poor;

(4) the blood oxygen condition in the change procedure, is inscribed during two neighbouring samples in time, and the concentration change of closing the oxygen haemoglobin is that Δ CHbO2 and reduced hemoglobin concentration change are Δ CHb, and available following formula is calculated:

${\mathrm{\ΔCHbO}}_2={\mathrm{\α}}_1{\mathrm{\ΔOD}}_k^{{\mathrm{\λ}}_1}-{\mathrm{\α}}_2{\mathrm{\ΔOD}}_k^{{\mathrm{\λ}}_2}$

$\mathrm{\ΔCHb}={\mathrm{\α}}_3{\mathrm{\ΔOD}}_k^{{\mathrm{\λ}}_1}-{\mathrm{\α}}_4{\mathrm{\ΔOD}}_k^{{\mathrm{\λ}}_2}$

α wherein ₁-α ₄For constant but relevant with wavelength,

Wavelength is λ ₁Down

α ₁Be-1.6～-2.5,

α ₃Be 2.6～3.85

Wavelength is λ ₂Down

α ₂Be-2.5～-3.6,

α ₄Be 0.61.6

(5) consider the influence of outer tissue thickness, the value of above-mentioned Δ CHbO2, Δ CHb revised, promptly to it divided by less than 1 factor y:

y＝ax ²+bx+c

Wherein, x is the thickness of outer tissue, x 〉=1mm; A, b, c can be respectively according to the hungry type value of outer tissue.

When outer tissue is under the situation of scalp, skull, cerebrospinal fluid, and when surveying Adult Human Brain oxygen, d is at least 50mm; When surveying baby's brain oxygen, d is 30mm at least.

Be that when fat thickness was greater than 15mm detecting muscle blood oxygen parameter, the d value was at least 50mm, otherwise is at least 40mm under the situation of fat deposit thickness of muscle when outer tissue.

When outer tissue was scalp, skull and cerebrospinal fluid, in the computing formula of correction factor y, the value of a was 0.0015-0.0018, and the b value is-0.08--0.093 that the c value is 1.01-1.05.

When detecting muscle blood oxygen parameter, in the computing formula of correction factor y, the value of a is 0.0012-0.0014, and the b value is-0.093--0.097 that the c value is 1.01-1.05.

Experimental results show that: the method that the present invention proposes reduces the effect of signals of outer tissue to deep layer, has also improved the intensity of light signal simultaneously, helps improving accuracy of detection, and the circuit of detection system also obtains simplifying.

Description of drawings:

Fig. 1 has the detection method synoptic diagram now.

Fig. 2 detection method synoptic diagram of the present invention.

Fig. 3 sensor outward appearance arrangenent diagram.

Revise in the tissue oxygenation parameter detecting that Fig. 4 the present invention proposes the outer tissue influence program flow diagram.

Fig. 5 hardware unit structural drawing.

Fig. 6 is human body forearm blocking-up test pattern.

The blood oxygen of the full blocking-up of Fig. 7 changes and the correction result.

Embodiment:

For the influence of outer tissue to accuracy of detection minimized.The present invention at first requires to determine suitably that according to the type of object outer tissue to be measured and thickness the light source on the sensor arrives detector distance d.The thickness of outer tissue can be obtained by the ultrasonic technique of routine.When outer tissue is thicker, then distance should be got bigger value, is deep into tissue to be measured to guarantee photon energy, and rule of thumb and experimental result, when surveying Adult Human Brain oxygen, d gets 50mm, surveys baby's brain d and gets 30mm.When fat thickness was greater than 15mm when surveying muscle, d got 50mm, is advisable otherwise get 40mm.Multilayer tissue's structure as shown in Figure 2.1 is to be the light source LS1 of r1 with optical sensor OPSU distance in Fig. 2, the 2nd, with optical sensor OPUS distance be the light source LS2 of r2, the 3rd, with optical sensor OPUS distance be the light source LS3 of r3, the 4th, optical sensor OPSU, 5 are the 1st layer tissue and represent with T1,6 are the 2nd layer tissue and represent that with T2 7 are the 3rd layer tissue and represent with T3, in the organize models that human muscular tissue's blood oxygen is measured, T1 is a skin, and T2 muscle hypodermis, T3 are musculature; In the organize models that human body brain blood oxygen is measured, T1 is a skin, and T2 is a skull, and T3 is brain tissue (grey matter and a white matter).B1, b2, b3 are the track of photon transport.Detect the tissue of different depth, LS is placed on the different distance with optical sensor OPUS, LS3 is luminous, and what detected by OPUS mainly is the information of T1 layer, and LS2 is luminous, and what detected by OPUS is the information of T1 and T2 layer, and LS1 is luminous, and what detected by OPUS mainly is the information of T1, T2 layer and T3 layer.Light source LS1, LS2, LS3 are r to the distance of OPUS ₁, r ₂, r ₃

As shown in Figure 3, the centre distance of three luminotron 1LED1,2LED2,3LED3 and the 4 photoelectric receiving tube OPUS on the sensor is respectively 50mm, 40mm and 30mm.Select a distance in fixed these three distances and make this lumination of light emitting diode according to the fat deposit thickness of muscle or the thickness of brain epidermis and skull in use, all the other two light emitting diodes are then not luminous.Each luminotron should be able to be launched the light of two kinds of wavelength respectively.Wavelength is respectively ruddiness and near infrared light, and is following with λ ₁, λ ₂The expression different wave length.The change amount of optical density OD by two wavelength correspondences calculates oxyhemoglobin variation delta HbO2 and reduced hemoglobin variation delta Hb.

Owing to have the outer tissue influence, therefore calculate the Δ CHbO of gained ₂All be less than actual value with Δ CHb.To remove one less than 1 coefficient y for this reason.The value of y depends on the thickness of outer tissue, and its relation can be obtained by simulation calculation, also can be obtained by experiment.It is considered herein that it can represent with quafric curve.Coefficient in the equation is by experiment decision in advance.

The effect of bringing after the invention process can reduce: (1) will make its parameter that records of experimenter of different outer tissue thickness have comparability, thereby the conclusion that draws in view of the above is only reliably, for a, b in the correct experimental formula definite of the present invention, c coefficient, be based on a large amount of emulation and experimental work.(2) under different tissues and corresponding outer tissue thickness, select suitable surely detection distance.

Program flow chart of the present invention is seen Fig. 4.

Use the detection system schematic block circuit diagram of the method for the invention formation and see Fig. 5.

The exemplary hardware device that goes out according to the diffused light principle design as shown in Figure 5.In use, at first utilize ultrasonic method to measure outer tissue thickness and one-tenth-value thickness 1/10 is imported instrument.One of them is selected by system from three LED 1LS, 2LS, 3LS, the principle of selection is: survey Adult Human Brain oxygen, select LS1, the baby gets LS3, surveys muscle when lipfanogen during greater than 15mm, selects LS1, gets LS2 less than 15mm.Detecting light intensity by photoelectric detector 4OPUS changes, OPUS selects 2CU30S, 4OPUS is connected to prime amplifier TLC27L2 signal is amplified, signal enters sampling holder LF398 and changes by analog-digital converter ADC TLC2543 under microcontroller AT89C52 control, and transformation result deposits storer in.By algorithm that provides in the method and step, calculate oxyhemoglobin variable quantity (Δ HbO ₂) with reduced hemoglobin variable quantity (Δ Hb) and proofreading and correct.

Detect human body forearm vein, artery and blocked situation entirely.Obtain Δ C _HbO2, Δ C _Hb, in order to the situation and the physiological change process of simulated human tissue anoxic.Fig. 6 is human body forearm blocking-up test pattern.Occluding pressure is more than the 240mHg, and system stability begins rapid pressurization after 110 seconds, finishes blocking-up after 230 seconds in blocking-up.Fig. 7 is the blood oxygen result of variations of full blocking-up, shows the Δ C of the full blocking-up of forearm as a result of proofreading and correct after outer tissue influences _HbO2, Δ C _HbChange curve; ^*Δ C before representative is proofreaied and correct _HbΔ C after the o representative is proofreaied and correct _HbΔ C before+representative is proofreaied and correct _HbO2Δ C after+representative is proofreaied and correct _HbO2(skin and fat thickness=5mm).Fig. 8 is the existing uncorrected curve of method.

Claims (5)

1. the tissue oxygenation parameter detection method of recoverable outer tissue influence comprises with the variable quantity of the haemoglobin that closes oxygen and reduction in the Near-infrared Double wave spectrum method detection of biological tissue, it is characterized in that: it uses three each self energy difference emission wavelengths to be λ ₁Ruddiness and wavelength be λ ₂The luminotron of infrared light form sensor with the photoelectric receiving tube that is positioned at a side, the centre distance d of three luminous light and photelectric receiver is at least 30mm, 40mm and 50mm, during detection according to the type of outer tissue therefrom choose have can the light emitting diode of centre distance, and only order this lumination of light emitting diode, be respectively λ according to detected wavelength ₁, λ ₂Optical density OD ^{λ i}I=1,2, calculate respectively two neighbouring samples constantly close the change amount Δ CHbO2 oxygen hemoglobin concentration and reduced hemoglobin concentration, Δ CHb, consider the influence of outer layer thickness again, divided by less than 1 correction factor, just can obtain revising the Δ CHbO2 behind the outer tissue thickness effect, the value of Δ CHb to the Δ CHbO2 that is calculated, Δ CHb; Above-described method has following steps successively:

(1), measures outer tissue thickness with ultrasonic method and select a fixed light emitting diode with photoelectric receiving tube apart from d according to the thickness of outer tissue according to the object of test and the position of test;

(2) detection optical density value OD under the centre distance of the photoelectric receiving tube of selected luminotron ^{λ i}I=1,2;

Wherein, I _{Go into}Be light source power, I _{Go out}Be that incident light passes through after biological tissue's scattering the luminous power that photoelectric receiving tube is received;

(3) detect the blood oxygen condition in time in the change procedure, two neighbouring sample optical density OD at interval ^{λ i}Difference OD _k ^{λ i}

$\mathrm{\Δ}{\mathrm{OD}}_k^{\mathrm{\λi}}={\mathrm{OD}}_{t+1}^{\mathrm{\λi}}-{\mathrm{OD}}_t^{\mathrm{\λi}}$

Wherein, OD ₁ ^{λ i}And OD _T+1 ^{λ i}Being respectively wavelength is λ _iThe time, at t constantly and subsequent t+1 optical density constantly poor;

(4) the blood oxygen condition in the change procedure, is inscribed during two neighbouring samples in time, and the concentration change of closing the oxygen haemoglobin is

Δ CHbO2 and reduced hemoglobin concentration change are Δ CHb, and available following formula is calculated:

${\mathrm{\ΔCHbO}}_2={\mathrm{\α}}_1\mathrm{\ΔO}{D}_k^{{\mathrm{\λ}}_1}-{\mathrm{\α}}_2\mathrm{\ΔO}{D}_k^{{\mathrm{\λ}}_2}$

$\mathrm{\ΔCHb}={\mathrm{\α}}_3\mathrm{\ΔO}{D}_k^{{\mathrm{\λ}}_1}-{\mathrm{\α}}_4\mathrm{\Δ}{\mathrm{OD}}_k^{{\mathrm{\λ}}_2}$

α wherein ₁-α ₄For constant but relevant with wavelength,

Wavelength is λ _iDown

α ₁Be-1.6～-2.5,

α ₃Be 2.6～3.85

Wavelength is λ ₂Down

α ₂Be-2.5～-3.6,

α ₄Be 0.6～1.6

(5) consider the influence of outer tissue thickness, the value of above-mentioned Δ CHbO2, Δ CHb revised, promptly to it divided by less than 1 factor y:

y＝ax ²+bx+c

Wherein, x is the thickness of outer tissue, x 〉=1mm; A, b, c can be respectively according to the hungry type value of outer tissue.

2. tissue blood-oxygen parameter detection method capable of amending outer layer tissue influence according to claim 1 is characterized in that: be under the situation of scalp, skull, cerebrospinal fluid when outer tissue, when surveying Adult Human Brain oxygen, d is at least 50mm; When surveying baby's brain oxygen, d is 30mm at least.

3. the tissue oxygenation parameter detection method that may revise the outer tissue influence according to claim 1, it is characterized in that: be under the situation of fat deposit thickness of muscle when outer tissue, when fat thickness is greater than 15mm detecting muscle blood oxygen parameter, the d value is at least 50mm, otherwise is at least 40mm.

4. tissue blood-oxygen parameter detection method capable of amending outer layer tissue influence according to claim 1 is characterized in that: when outer tissue is scalp, skull and cerebrospinal fluid, in the computing formula of correction factor y, the value of a is 0.0015-0.0018, the b value is-0.08--0.093 that the c value is 1.01-1.05.

5. tissue blood-oxygen parameter detection method capable of amending outer layer tissue influence according to claim 1 is characterized in that: when detecting muscle blood oxygen parameter, in the computing formula of correction factor y, the value of a is 0.0012-0.0014, the b value is-0.093--0.097 that the c value is 1.01-1.05.

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