WO2016106748A1

WO2016106748A1 - Method and device for monitoring venous oxygen saturation

Info

Publication number: WO2016106748A1
Application number: PCT/CN2014/096059
Authority: WO
Inventors: 张旭; 叶继伦; 罗赛; 陈思平
Original assignee: 深圳大学
Priority date: 2014-12-31
Filing date: 2014-12-31
Publication date: 2016-07-07

Abstract

Disclosed is a method for monitoring the venous oxygen saturation, comprising boosting the signal strength of venous blood (102); collecting excitation signals, and separating artificially added excitation signals from pulse wave signals generated by cardiac pumping (104); obtaining the venous oxygen saturation by means of venous signals contained in the artificially added excitation signals (106). Disclosed is a device for monitoring the venous oxygen saturation, comprising an excitation module for boosting the signal strength of venous blood; a signal acquisition module for collecting excitation signals, and separating artificially added excitation signals from pulse wave signals generated by cardiac pumping; and a computation module for obtaining the venous oxygen saturation by venous signals contained in the artificially added excitation signals. The device achieves the continuous non-invasive measurement of the venous oxygen saturation, which saves costs, is easily used, and decreases usage risks.

Description

Method and apparatus for monitoring venous oxygen saturation

Technical field

The present application relates to the medical field, and in particular, to a method and apparatus for monitoring venous oxygen saturation.

Background technique

The content of O2 in blood has important reference significance for clinicians in the treatment of OR (operating room) and ICU (intensive care unit). Clinically, the incidence of abnormalities in these components is beyond the imagination of people and cannot be timely and correct. The measurement can lead to misdiagnosis or even crisis for the patient's life. Therefore, the monitoring of blood gas in patients has become an indispensable test item for critically ill patients' intensive care units, heart disease intensive care units, operating rooms and emergency departments. It has important reference significance for clinicians in the treatment of OR and ICU.

Many parameters in clinical monitoring have been able to achieve continuous non-invasive monitoring. For example, SpO2 (arterial oxygen saturation) has been used as a mandatory parameter in the guidelines of departments such as ICU. At the same time, due to the mature development of the SpO2 measurement method, the detection of SpO2 can be carried out in real time and non-invasively. It can accurately respond to the patient's oxygen supply and make a direct or indirect real-time judgment on whether the patient's breathing and circulation are normal. . However, in fact, the measurement of SpO2 only reflects the oxygen supply. If you want to correctly determine the oxygen consumption of the patient's tissues and organs, and whether the oxygen metabolism is normal, you must measure SvO2 (venous oxygen saturation), and judge the oxygen metabolism by the difference between the two. Happening. There are many related discussions about oxygen supply and oxygen consumption. So far, the methods for measuring SvO2 used in clinical practice at home and abroad are invasive measurement methods. By blood sampling or floating catheter, spectral alignment method is adopted. This type of method is very demanding, not only complicated in operation but also aggravating the patient's pain, and the measurement cost is very high. Whether it is a floating catheter as a consumable or a reagent for measuring the collected blood sample of the patient, it requires a high cost and aggravates the medical staff. The operational burden is also increased by the corresponding cost, and the risk of application is also great.

Summary of the invention

The present application provides a method and apparatus for monitoring venous oxygen saturation.

According to a first aspect of the present application, the present application provides a method of monitoring venous oxygen saturation, comprising:

Enhance the signal intensity of venous blood;

Collecting an excitation signal, separating the artificially added excitation signal and the pulse wave signal generated by the heart pumping blood;

Venous oxygen saturation is obtained by the artificial addition of a vein signal contained in the excitation signal.

In the above method, the enhancing venous blood signal comprises:

The signal intensity of venous blood is enhanced by emitting an excitation signal.

In the above method, the signal intensity of the venous blood is enhanced by issuing an excitation signal, which specifically includes:

A periodic pressure signal is added at the extremity of the limb, and the venous blood vessel is squeezed to produce regular contraction and diastolic amplification of the venous blood signal intensity.

In the above method, the separating manually adds an excitation signal and a pulse wave signal generated by the heart pumping, including:

Adjusting the excitation signal such that the artificially added excitation signal is in a different frequency domain than the pulse wave signal generated by the heart pumping;

The artificially added excitation signal and the pulse wave signal are separated by filtering and windowing.

In the above method, the separating manually adding the excitation signal and the pulse wave signal generated by the blood pumping by the heart further includes:

The intensity and frequency of the artificially added excitation signal are adjusted using the excitation signal actually received by the separated blood as feedback.

According to a second aspect of the present application, the present application provides an apparatus for monitoring venous oxygen saturation, comprising:

An excitation module for enhancing the signal intensity of venous blood;

a signal acquisition module for collecting an excitation signal, separating the artificially added excitation signal and the pulse wave signal generated by the heart pumping blood;

And a calculation module, configured to obtain venous oxygen saturation by the artificially adding a venous blood signal included in the excitation signal.

In the above device, the excitation module is further configured to enhance the intensity of the venous blood signal by emitting an excitation signal.

In the above device, the excitation module is further configured to add a periodic pressure signal to the extremity of the limb, and the venous blood vessel is squeezed to generate a regular contraction and to relax the signal intensity of the venous blood.

In the above device, the signal acquisition module is further configured to adjust the excitation signal to cause the artificially added excitation signal to be at a different frequency from the pulse wave signal generated by blood pumping by the heart. a domain, the artificially added excitation signal and the pulse wave signal are separated by filtering and windowing.

In the above device, the signal acquisition module is further configured to use the excitation signal actually received by the separated blood as feedback to adjust the intensity and frequency of the artificially added excitation signal.

Due to the adoption of the above technical solutions, the beneficial effects of the present application are as follows:

In a specific embodiment of the present application, the signal intensity of the venous blood is first enhanced, the excitation signal is collected, the artificially added excitation signal and the pulse wave signal generated by the heart pumping are separated, and the vein included in the excitation signal is manually added by the manual. The signal acquires venous oxygen saturation. The present application can achieve continuous non-invasive measurement of venous oxygen saturation, and saves cost, is simple to use, and significantly reduces application risk compared to existing invasive monitoring methods.

DRAWINGS

1 is a timing diagram of light source control in an embodiment of the method of the present application;

2 is a schematic diagram of a signal spectrum of a finger end spectral absorption model under static conditions;

3 is a schematic diagram of sensor receiving signals of a finger end spectral absorption model under static conditions;

4 is a schematic diagram of a signal spectrum of a finger end spectral absorption model under motion conditions;

5 is a schematic diagram of sensor receiving signals of a finger end spectral absorption model under motion conditions;

Figure 6 is a flow chart of the method of the present application in an embodiment;

7 is a schematic diagram of a spectrum of a red light infrared light signal;

Figure 8 is a schematic view showing the pulsation of the simulated arterial pulsation in the present application;

9 is a schematic diagram of a control process of an apparatus of the present application in an embodiment.

detailed description

The present application will be further described in detail below with reference to the accompanying drawings.

The present application enhances the intensity of a vein signal whose original signal is very weak under normal conditions by artificially adding an excitation method. Under normal circumstances, the vein signal is very weak, so it is difficult to collect. By artificially adding the excitation method, the original signal signal with weak signal intensity is enhanced, so that the vein signal that is not easy to collect is easily collected, and the signal of the vein signal is enhanced. Noise ratio.

In general, the venous blood oxygen signal is present as noise in the background of the arterial blood oxygen signal, which is filtered as a noise signal during the measurement of SpO2. The purpose of this project is precisely to measure this venous blood oxygen signal, which is usually considered the background. And Due to the presence of pulse fluctuations, the SvO2 signal strength is much smaller than the SpO2 signal strength. How to extract the weak venous blood oxygen signal in the background is very difficult and one of the core problems to be solved in this project. The experience of SpO2 measurement in the past shows that the venous signal is more powerful as an interference signal only under the condition that the patient's limb is seriously shaken. This patent will use this phenomenon to introduce an external excitation signal using equipment such as airbags and vibration motors. Increase the signal intensity of the venous movement of the tested site to achieve continuous non-invasive measurement of SvO2. This project will use a similar method of SpO2 measurement to non-invasively measure venous oxygen saturation SvO2.

The spectral absorption model of the human finger end under quiet conditions is shown in Figure 1. Where Δt1 represents the red light drive level duration, Δt3 represents the infrared light drive level duration, Δt2, Δt4 represents the ambient light drive level duration, and signals such as veins, skeletal muscles, etc. exist as base signals, only the arteries The pulse fluctuations in the cycle are periodic motion signals. As can be seen in Figure 2, the spectrum is a typical periodic signal spectrum, and the signal information of each harmonic reaction is completely consistent. Since the fluctuation of the arteries is far stronger than the fluctuation of the veins, the curve indicated by the solid line in the figure is the intensity of the venous pulsation spectrum absorption signal, which is much smaller than the curve indicated by the dotted line, which absorbs the signal intensity of the arterial pulsation spectrum, and the venous beat spectrum absorbs the signal intensity far. Less than the arterial beat spectrum absorbs the signal intensity. Under normal conditions, during the measurement of arterial oxygen saturation, the acquired venous oxygen saturation SvO2 signal is a background noise signal, which is insufficient to meet the needs of stable continuous measurement. Therefore, special methods should be taken to improve the signal to noise ratio. Figure 3 is a schematic diagram of the sensor receiving signal of the finger end spectral absorption model under static conditions.

The spectral absorption model of the human finger end under the motion condition is shown in Fig. 4 and Fig. 5. The absorption of the bone and other tissues is still the base, and the absorption of the spectrum by the venous blood is no longer the base but the fluctuation of the movement. The signal after the movement of the finger and the fluctuation of the pulse is shown in Fig. 5, and the corresponding spectrum is shown in Fig. 4. It can be seen that the spectrum caused by motion is inconsistent with the spectrum of arterial fluctuations.

Clinical trials have found that this movement enhances venous oxygen signals when there is motion in the part of the patient's site. The patient's limb movement is a completely unconscious movement, so it is also a kind of interference movement without exchange rate. This movement is not only a very bad interference signal in the process of measuring arterial oxygen saturation, but often leads to Arterial oxygen saturation measurements are incorrect; and due to their irregularities, it is difficult to extract such signals to measure venous oxygen saturation.

The present invention makes it possible to amplify the venous fluctuation signal by actively generating an excitation signal; and by controlling the excitation signal, the signal of the venous fluctuation becomes a regular periodic signal and the frequency and amplitude are adjustable to achieve venous oxygen saturation. The signal is easy to separate and improve the signal-to-noise ratio during the measurement process.

Embodiment 1:

As shown in FIG. 6, an embodiment of the method for monitoring venous oxygen saturation of the present application includes the following steps:

Step 102: Enhance the signal intensity of venous blood.

Step 104: Acquire an excitation signal, and separate the artificially added excitation signal and the pulse wave signal generated by the heart pumping blood.

Step 106: Obtain venous oxygen saturation by manually adding a vein signal contained in the excitation signal.

In step 102, the signal intensity of the venous blood can be enhanced by emitting an excitation signal. If a periodic pressure signal is added at the end of the limb, the venous blood vessel is squeezed to produce regular contraction and diastolic amplification of the venous blood signal intensity.

In step 104, separating the artificially added excitation signal and the pulse wave signal generated by the blood pumping by the heart, specifically includes:

Step 1042: adjusting the excitation signal to cause the artificially added excitation signal to be in a different frequency domain from the pulse wave signal generated by blood pumping by the heart;

Step 1044: Separating the artificially added excitation signal from the pulse wave signal by filtering and windowing.

In step 104, after separating the artificially added excitation signal and the pulse wave signal generated by the blood pumping by the heart, the method may further include:

As shown in FIG. 7 and FIG. 8, the present application firstly inflates and deflates the excitation finger 11 through the air pump, and adds a periodic pressure signal to the root of the finger. The venous blood vessels are squeezed to produce regular contraction and relaxation, thereby simulating the form of arterial pulsation to produce venous pulsations. The artificially added venous beat signal needs to be distinguished from the arterial beating signal generated by the heart beat in frequency in order to separate the arterial signal from the venous signal in the frequency domain.

Figure 8 depicts the process of probe drive, excitation control, and signal acquisition. The light source 12 and the sensor 13 respectively measure the commonly used 660 nm red light and 880 nm or 940 nm infrared light and a photodiode using pulse oxygen. Firstly, according to the sequence shown in Figure 1, the light source is turned on and off, and then the signal acquisition channel is used to amplify and collect the response signals of the photodiode to the red and infrared light after penetrating the human body, as shown in Equation 1, Y(F, I) represents the output signal obtained by the acquisition end, X_Artery (F, I), X_Stimulate (F, I) respectively represent the arterial signal component and the excitation signal Number component. Wherein, the arterial signal is used as a reference before the excitation signal is added, and the excitation signal is prevented from aliasing with the arterial signal in the frequency domain. Where F is the signal frequency and I is the signal strength. Since the excitation signal and the arterial pulse signal are separated in the frequency domain, the artery signal and the excitation signal can be separated by filtering and windowing, and the separated signal is used as a feedback parameter to control the intensity and frequency of the excitation signal to avoid Heart rate conversion results in aliasing of the arterial and excitation signals in the frequency domain. As shown in

Equations

3 and 4, the frequency and intensity of the currently added excitation signal are determined by calculating the frequency difference between the arterial signal and the mixed vein signal at the previous time and the difference in signal intensity. F_Stimulate(t) represents the frequency of the excitation signal, and F_Artery(t) represents the frequency of the arterial signal.

Y(F,I)=X_Artery(F,I)+X_Stimulate(F,I) (1)

The spectrum of red and infrared light signals after adding artificial excitation is shown in Fig. 9. Among them, the peak around 12HZ is the excitation signal peak, and the peak around 1HZ is the peak of the arterial pulsation. The excitation peak actually includes the venous signal and the arterial signal, and the venous oxygen saturation of the pulse oximetry and the excitation peak of the arterial peak are calculated by the

comprehensive formulas

2, 3, and 4, respectively, wherein SpO2 represents arterial oxygen saturation, and SvO ₂ represents The venous oxygen saturation generated by the excitation signal, RED_AC represents the red light AC value, RED_DC represents the red light DC value, IR_AC represents the infrared light AC value, IR_DC represents the infrared light DC value, R is dimensionless, R _a , R _v respectively represent the artery The R value corresponding to oxygen saturation and venous oxygen saturation.

In addition to adding an excitation signal through the excitation ring, an excitation signal can be added by installing a DC motor with an eccentricity. The rotation of the DC motor drives the regular movement of the eccentric block, while the movement with the eccentricity drives the human body to move regularly. The frequency of the motion can be controlled by controlling the speed of the DC motor. The finger is regularly moved by the excitation of the vibrator module added to the probe. A periodic motion disturbance signal is introduced into the venous blood to artificially control the frequency of motion disturbances.

Embodiment 2:

An embodiment of the apparatus for monitoring venous oxygen saturation of the present application comprises: an excitation module, a signal acquisition module, and a calculation module. Incentive module for enhancing venous blood No. intensity; a signal acquisition module for collecting the excitation signal, separating the artificially added excitation signal and the pulse wave signal generated by the heart pumping; and a calculation module for obtaining venous blood by manually adding the venous blood signal contained in the excitation signal Oxygen saturation.

In one embodiment, the excitation module is further configured to enhance the intensity of the venous blood signal by issuing an excitation signal.

In another embodiment, the excitation module is further configured to add a periodic pressure signal at the extremity of the limb, the venous blood vessel being squeezed to produce a regular contraction and to relax the signal intensity of the venous blood.

In the device for monitoring venous oxygen saturation of the present application, the signal acquisition module is further configured to adjust the excitation signal so that the artificially added excitation signal and the pulse wave signal generated by the heart pumping are in different frequency domains, and are separated by filtering and windowing. The excitation signal and the pulse wave signal are manually added.

In one embodiment, the signal acquisition module is further configured to use the excitation signal actually received by the separated blood as feedback to adjust the intensity and frequency of the artificially added excitation signal.

The above content is a further detailed description of the present application in conjunction with the specific embodiments, and the specific implementation of the present application is not limited to the description. For the ordinary person skilled in the art to which the present invention pertains, a number of simple deductions or substitutions may be made without departing from the spirit of the present application.

Claims

A method for monitoring venous oxygen saturation, comprising:

Enhance the signal intensity of venous blood;

Collecting an excitation signal, separating the artificially added excitation signal and the pulse wave signal generated by the heart pumping blood;

Venous oxygen saturation is obtained by the artificial addition of a vein signal contained in the excitation signal.
A method of monitoring venous oxygen saturation as claimed in claim 1 wherein said enhancing venous blood signal comprises:

The signal intensity of venous blood is enhanced by emitting an excitation signal.
The method of monitoring venous oxygen saturation according to claim 2, wherein the enhancing the signal intensity of the venous blood by emitting an excitation signal comprises:

A periodic pressure signal is added at the extremity of the limb, and the venous blood vessel is squeezed to produce regular contraction and diastolic amplification of the venous blood signal intensity.
The method of monitoring venous oxygen saturation according to claim 3, wherein said separating manually adding an excitation signal to a pulse wave signal generated by blood pumping by the heart comprises:

Adjusting the excitation signal such that the artificially added excitation signal is in a different frequency domain than the pulse wave signal generated by the heart pumping;

The artificially added excitation signal and the pulse wave signal are separated by filtering and windowing.
The method of monitoring venous oxygen saturation according to claim 4, wherein the separating the artificially adding the excitation signal and the pulse wave signal generated by the blood pumping by the heart, further comprising:

The intensity and frequency of the artificially added excitation signal are adjusted using the excitation signal actually received by the separated blood as feedback.
A device for monitoring venous oxygen saturation, comprising:

An excitation module for enhancing the signal intensity of venous blood;

a signal acquisition module for collecting an excitation signal, separating the artificially added excitation signal and the pulse wave signal generated by the heart pumping blood;

And a calculation module, configured to obtain venous oxygen saturation by the artificially adding a venous blood signal included in the excitation signal.
A device for monitoring venous oxygen saturation as claimed in claim 6 The excitation module is further configured to enhance the intensity of the venous blood signal by issuing an excitation signal.
The device for monitoring venous oxygen saturation according to claim 7, wherein said excitation module is further configured to add a periodic pressure signal at the extremity of the limb, and the venous blood vessel is squeezed to produce a regular contraction and a diastolic augmentation vein. The signal strength of the blood.
The apparatus for monitoring venous oxygen saturation according to claim 8, wherein said signal acquisition module is further configured to: said artificially add an excitation signal to said cardiac pumping by said heart pumping by adjusting an excitation signal The pulse wave signals are in different frequency domains, and the artificially added excitation signal and the pulse wave signal are separated by filtering and windowing.
The device for monitoring venous oxygen saturation according to claim 7, wherein the signal acquisition module is further configured to use the excitation signal actually received by the separated blood as feedback to adjust the artificially added excitation signal. Strength and frequency.