CN111741714A - Blood oxygen measuring system and method - Google Patents
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- 210000004369 blood Anatomy 0.000 title claims description 118
- 239000008280 blood Substances 0.000 title claims description 118
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 title claims description 84
- 229910052760 oxygen Inorganic materials 0.000 title claims description 84
- 239000001301 oxygen Substances 0.000 title claims description 84
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- 238000002496 oximetry Methods 0.000 claims abstract description 44
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- A61B5/1455—Measuring characteristics of blood in vivo, e.g. gas concentration, pH value; Measuring characteristics of body fluids or tissues, e.g. interstitial fluid, cerebral tissue using optical sensors, e.g. spectral photometrical oximeters
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Abstract
An oximetry system (50, 100) and method, wherein the system (50, 100) comprises: the light source control circuit (1010) controls at least one path of light source (1, 1020) to periodically emit light; the signal receiving circuit (1030) collects optical signals which are generated by at least one path of light source (1, 1020) and pass through the physiological tissue (2), converts the collected optical signals into electric signals, and samples and quantizes the amplified electric signals; a first filtering module (1040) filters a noise portion of the electrical signal prior to demodulating the electrical signal; the signal processing module (1050) demodulates the electrical signal processed by the first filtering module (1040) to obtain a digital incoming sample signal containing at least one physiological characteristic. At least one physiological parameter is calculated according to the digital incoming sample signal. An improved accuracy of the oximetry system (50, 100) in measuring the physiological parameter may be achieved.
Description
The application relates to the technical field of medical products, in particular to a blood oxygen measuring system and method.
With the expansion of the range of pulse oximetry use, the performance requirements of medical personnel on oximetry have also been gradually increased. The main performance indicators of the pulse oximeter are weak perfusion performance, anti-motion performance and anti-ambient light interference performance. Poor perfusion performance means that patients with poor peripheral circulation status cannot be evaluated or the measurement results are inaccurate. Poor resistance to movement means that the true physiological state of the patient with the moving measurement site cannot be accurately monitored. The poor performance of environmental light interference resistance means that the accuracy of the blood oxygen measurement result can be affected by the ambient light around the blood oxygen probe, such as incandescent light, fluorescent light, blue light, shadowless light and other light sources, and even the blood oxygen probe still displays the measurement value after falling off from the measurement position.
Peripheral blood circulation perfusion of the neonate is weak, and the requirement on weak perfusion performance of an oximeter is high. Involuntary activity of the limbs of the neonate results in the oximeter being susceptible to movement disturbances. The bandage probe is mostly used for monitoring blood oxygen of the newborn, the attachment of the probe and a measuring part is poor after four limbs move, light leakage is caused, and the inherent light transmittance of the measuring part is added, so that ambient light (such as a blue light lamp for treating jaundice, an incandescent lamp for illumination and a fluorescent lamp) is received by the probe and interferes with an oximeter. The above-mentioned challenges are present in the NICU department room at the same time, and the requirements for pulse oximeter performance are more stringent.
Disclosure of Invention
The embodiment of the application provides a blood oxygen measuring system and a blood oxygen measuring method, which can improve the accuracy of measuring the blood oxygen saturation.
In a first aspect, an embodiment of the present application provides an oximetry system, including: the device comprises at least one path of light source, a light source control circuit, a signal receiving circuit, a first filtering module, a signal processing module and a controller;
the light source control circuit is used for controlling the at least one path of light source to periodically emit light;
the signal receiving circuit is used for collecting optical signals which are generated by the at least one path of light source and pass through physiological tissues; the collected optical signals comprise optical signals in the light-emitting period and optical signals in the non-light-emitting period of the at least one path of light source;
the signal receiving circuit is also used for converting the collected optical signals into electric signals; the electric signal contains at least one physiological characteristic information of the physiological tissue;
the first filtering module is used for filtering a noise part in the electric signal before demodulating the electric signal;
the signal processing module is used for demodulating the electric signal processed by the first filtering module to obtain a digital sampling signal containing at least one physiological characteristic; the digital sampled signal contains signal characteristics of a non-noise portion of the electrical signal;
the controller is used for calculating at least one physiological parameter according to the digital sampling signal.
With reference to the first aspect, in a first implementation manner of the first aspect, the noise part in the electrical signal includes ambient light noise and circuit random noise with a frequency outside a pass band of the first filtering module;
the first filtering module is specifically configured to:
and filtering ambient light noise and circuit random noise in the electric signal before demodulating the electric signal, and eliminating aliasing interference of the ambient light noise in the electric signal to a non-noise part in the electric signal.
With reference to the first implementation manner of the first aspect, in a second implementation manner of the first aspect, the ambient light noise includes, but is not limited to, a noise signal caused by light with a frequency N times a power frequency emitted by one or more light sources operating with an ac power source in a surrounding environment of the system, where N is a positive integer greater than 1;
the aliasing interference is used for representing a physical phenomenon that a noise part in the electric signal generates irreversible frequency distortion after being demodulated by the signal processing module and falls into a physiological bandwidth wholly or partially; the physiological bandwidth is used to characterize a frequency range of the physiological signal; the physiological signal is used for characterizing the signal caused by the periodic change of the blood layer thickness in the physiological tissue caused by the pulse beat.
With reference to the first aspect or the first to second implementation manners of the first aspect, in a third implementation manner of the first aspect, the first filtering module includes a low-pass filtering module; the first filtering cut-off frequency of the low-pass filtering module comprises 2 times or more of the periodic light-emitting frequency of the at least one path of light source;
the low-pass filtering module is used for filtering noise parts in the electric signals beyond the first filtering cut-off frequency before demodulation.
With reference to the third implementation manner of the first aspect, in a fourth implementation manner of the first aspect, the first filtering module further includes a high-pass filtering module; the second filtering cut-off frequency of the high-pass filtering module is half or less than the periodic light-emitting frequency of the at least one path of light source;
the high-pass filtering module is used for filtering noise parts in the electric signal beyond the second filtering cut-off frequency before demodulating the electric signal.
With reference to the first aspect or the first to second implementation manners of the first aspect, in a fifth implementation manner of the first aspect, the first filtering module includes a band-pass filtering module; the upper cut-off frequency of the band-pass filter module comprises 2 times or more of the periodic light-emitting frequency of the at least one path of light source, and the lower cut-off frequency of the band-pass filter module comprises half or less of the periodic light-emitting frequency of the at least one path of light source;
the band-pass filtering module is used for filtering the upper cut-off frequency of the band-pass filtering module to the noise part of the electric signal beyond the lower cut-off frequency of the band-pass filtering module before demodulating the electric signal.
With reference to the first implementation manner of the first aspect, in a sixth implementation manner of the first aspect, the non-noise part of the electrical signal is a physiological signal or a signal modulated by the physiological signal and having a frequency within a passband of the first filtering module; the physiological signal is used for characterizing the signal caused by the periodic change of the blood layer thickness in the physiological tissue caused by the pulse beat.
With reference to the first aspect, in a seventh implementation manner of the first aspect, the method further includes: the second filtering module is used for filtering the noise part of the digital sampling signal obtained by the signal processing module; the noise part of the digital sampling signal comprises but is not limited to ambient light noise with frequency outside physiological bandwidth, circuit random noise and/or circuit power frequency interference; the physiological bandwidth is used for characterizing a frequency range of the physiological signal, and the physiological signal is used for characterizing a signal caused by the periodic change of the blood layer thickness in the physiological tissue caused by the pulse beat.
With reference to the first aspect, in an eighth implementation form of the first aspect, the at least one physiological parameter includes, but is not limited to, pulse rate, blood oxygen saturation, perfusion index, pulse sound, and/or photoplethysmography;
the at least one light source includes, but is not limited to, infrared light, red light, green light and/or white light;
the light source control circuit is further configured to adjust a driving current required by the at least one path of light source to emit light, a driving voltage value required by the at least one path of light source to emit light, a light emitting pulse width and/or a light emitting frequency.
In a second aspect, an embodiment of the present application provides a blood oxygen measurement method, including:
controlling at least one path of light source to periodically emit light;
collecting optical signals which are generated by the at least one path of light source and pass through physiological tissues; the collected optical signals comprise optical signals in a light-emitting period and optical signals in a non-light-emitting period of the at least one path of light source;
converting the collected optical signals into electrical signals; the electric signal contains at least one physiological characteristic information of the physiological tissue;
filtering a noise portion of the electrical signal prior to demodulating the electrical signal;
demodulating the electrical signal after filtering the noise portion to obtain a digital sampled signal containing at least one physiological characteristic; the digital sampled signal contains signal characteristics of a non-noise portion of the electrical signal;
and calculating at least one physiological parameter according to the digital sampling signal.
With reference to the second aspect, in a first implementation manner of the second aspect, the noise part in the electrical signal includes ambient light noise and circuit random noise with frequencies outside a filtering passband;
the filtering the noise part in the electrical signal before demodulating the electrical signal specifically includes:
and filtering ambient light noise and circuit random noise in the electric signal before demodulating the electric signal, and eliminating aliasing interference of the ambient light noise in the electric signal to a non-noise part in the electric signal.
With reference to the first implementation manner of the second aspect, in a second implementation manner of the second aspect, the ambient light noise includes, but is not limited to, a light-induced noise signal with a frequency N times a power frequency emitted by one or more light sources operating with an ac power source in a surrounding environment of the system, where N is a positive integer greater than 1;
the aliasing interference is used for representing a physical phenomenon that a noise part in the electric signal is subjected to irreversible frequency distortion after being demodulated and falls into a physiological bandwidth wholly or partially; the physiological bandwidth is used to characterize a frequency range of the physiological signal; the physiological signal is used for characterizing the signal caused by the periodic change of the blood layer thickness in the physiological tissue caused by the pulse beat.
With reference to the second aspect or the first to second implementation manners of the second aspect, in a third implementation manner of the second aspect, the filtering the noise part in the electrical signal before demodulating the electrical signal specifically includes:
filtering, with low-pass filtering, a noise portion of the electrical signal outside a first filter cutoff frequency of the low-pass filtering prior to demodulation; the first filtering cut-off frequency comprises 2 times or more than 2 times of the periodic light-emitting frequency of the at least one path of light source;
with reference to the third implementation manner of the second aspect, in a fourth implementation manner of the second aspect, the filtering a noise portion in the electrical signal before demodulating the electrical signal specifically further includes:
filtering, with high-pass filtering, noise portions in the electrical signal outside a second cut-off frequency of the high-pass filtering before demodulating the electrical signal; the second filtering cut-off frequency comprises half or less of the periodic light-emitting frequency of the at least one path of light source.
With reference to the second aspect or the first to second implementation manners of the second aspect, in a fifth implementation manner of the second aspect, the filtering the noise part in the electrical signal before demodulating the electrical signal specifically includes:
filtering, with band-pass filtering, a noise portion in the electrical signal outside of an upper cutoff frequency of the band-pass filtering to a lower cutoff frequency of the band-pass filtering before demodulating the electrical signal;
the upper cut-off frequency of the band-pass filter comprises 2 times or more than 2 times of the periodic light-emitting frequency of the at least one path of light source, and the lower cut-off frequency of the band-pass filter comprises half or less than half of the periodic light-emitting frequency of the at least one path of light source.
With reference to the first implementation manner of the second aspect, in a sixth implementation manner of the second aspect, the non-noise part of the electrical signal includes a physiological signal or a signal modulated by the physiological signal and having a frequency within a filtering passband; the physiological signal is used for characterizing the signal caused by the periodic change of the blood layer thickness in the physiological tissue caused by the pulse beat.
With reference to the second aspect, in a seventh implementation manner of the second aspect, the method further includes:
filtering a noise portion of the digitally sampled signal; the noise part of the digital sampling signal comprises but is not limited to ambient light noise with frequency outside physiological bandwidth, circuit random noise and/or circuit power frequency interference; the physiological bandwidth is used for characterizing a frequency range of the physiological signal, and the physiological signal is used for characterizing a signal caused by the periodic change of the blood layer thickness in the physiological tissue caused by the pulse beat.
With reference to the second aspect, in an eighth implementation form of the second aspect, the at least one physiological parameter includes, but is not limited to, pulse rate, blood oxygen saturation, perfusion index, pulse sound, and/or photoplethysmography;
the at least one light source includes, but is not limited to, infrared light, red light, green light and/or white light;
the method further comprises the following steps:
and adjusting the driving current value, the driving voltage value, the light-emitting pulse width and/or the light-emitting frequency required by the light emission of the at least one path of light source.
In a third aspect, the present application provides a blood oximetry system comprising: the device comprises a control unit, an acquisition unit, a conversion unit, a first filtering unit, a processing unit and an operation unit; wherein the content of the first and second substances,
the control unit is used for controlling at least one path of light source to periodically emit light;
the acquisition unit is used for acquiring optical signals which are generated by the at least one path of light source and pass through physiological tissues; the collected optical signals comprise optical signals in a light-emitting period and optical signals in a non-light-emitting period of the at least one path of light source;
the conversion unit is used for converting the collected optical signals into electric signals; the electric signal contains at least one physiological characteristic information of the physiological tissue;
the first filtering unit is used for filtering a noise part in the electric signal before demodulating the electric signal;
the processing unit is used for demodulating the electric signal after the noise part is filtered to obtain a digital sampling signal containing at least one physiological characteristic; the digital sampled signal contains signal characteristics of a non-noise portion of the electrical signal;
and the arithmetic unit is used for calculating at least one physiological parameter according to the digital sampling signal.
With reference to the third aspect, in a first implementation manner of the third aspect, the noise part in the electrical signal includes ambient light noise and circuit random noise with a frequency outside a filtering passband;
the first filtering unit is specifically configured to:
and filtering ambient light noise and circuit random noise in the electric signal before demodulating the electric signal, and eliminating aliasing interference of the ambient light noise in the electric signal to a non-noise part in the electric signal.
With reference to the first implementation manner of the third aspect, in a second implementation manner of the third aspect, the ambient light noise includes, but is not limited to, a noise signal caused by light with a frequency N times a power frequency emitted by one or more light sources operating with an ac power source in a surrounding environment of the system, where N is a positive integer greater than 1;
the aliasing interference is used for representing a physical phenomenon that a noise part in the electric signal is subjected to irreversible frequency distortion after being demodulated and falls into a physiological bandwidth wholly or partially; the physiological bandwidth is used to characterize a frequency range of the physiological signal; the physiological signal is used for characterizing the signal caused by the periodic change of the blood layer thickness in the physiological tissue caused by the pulse beat.
With reference to the third aspect or the first to second implementation manners of the third aspect, in a third implementation manner of the third aspect, the first filtering unit is specifically configured to:
filtering, with low-pass filtering, a noise portion of the electrical signal outside a first filter cutoff frequency of the low-pass filtering prior to demodulation; the first filtering cut-off frequency comprises 2 times or more of the periodic light-emitting frequency of the at least one path of light source;
with reference to the third implementation manner of the third aspect, in a fourth implementation manner of the third aspect, the first filtering unit is further specifically configured to:
filtering, with high-pass filtering, noise portions in the electrical signal outside a second cut-off frequency of the high-pass filtering before demodulating the electrical signal; the second filtering cut-off frequency comprises half or less of the periodic light-emitting frequency of the at least one path of light source.
With reference to the third aspect or the first to second implementation manners of the third aspect, in a fifth implementation manner of the third aspect, the first filtering unit is specifically configured to:
filtering, with band-pass filtering, a noise portion in the electrical signal outside of an upper cutoff frequency of the band-pass filtering to a lower cutoff frequency of the band-pass filtering before demodulating the electrical signal;
the upper cut-off frequency of the band-pass filter comprises 2 times or more of the periodic light-emitting frequency of the at least one path of light source, and the lower cut-off frequency of the band-pass filter comprises half or less of the periodic light-emitting frequency of the at least one path of light source.
With reference to the first implementation manner of the third aspect, in a sixth implementation manner of the third aspect, the non-noise part of the electrical signal includes a physiological signal or a signal modulated by the physiological signal and having a frequency within a filtering passband; the physiological signal is used for characterizing the signal caused by the periodic change of the blood layer thickness in the physiological tissue caused by the pulse beat.
With reference to the third aspect, in a seventh implementation manner of the third aspect, the method further includes:
a second filtering unit for filtering a noise part of the digital sampling signal obtained by the processing unit; the noise part of the digital sampling signal comprises but is not limited to ambient light noise with frequency outside physiological bandwidth, circuit random noise and/or circuit power frequency interference; the physiological bandwidth is used for characterizing a frequency range of the physiological signal, and the physiological signal is used for characterizing a signal caused by the periodic change of the blood layer thickness in the physiological tissue caused by the pulse beat.
With reference to the third aspect, in an eighth implementation form of the third aspect, the at least one physiological parameter includes, but is not limited to, pulse rate, blood oxygen saturation, perfusion index, pulse sound, and/or photoplethysmography;
the at least one light source includes, but is not limited to, infrared light, red light, green light and/or white light;
the system, still include:
and the adjusting unit is used for adjusting the driving current required by the at least one path of light source to emit light, the driving voltage value required by the light emission, the light emitting pulse width and/or the light emitting frequency.
In a fourth aspect, the present application provides a computer readable storage medium storing a computer program comprising program instructions which, when executed by a controller, cause the controller to perform the method of the second aspect described above.
In a fifth aspect, the present application provides a computer program comprising program instructions which, when executed, cause the controller to perform the method of the second aspect described above.
The embodiment of the application has the following beneficial effects:
the blood oxygen measuring system provided by the application controls at least one path of light source to periodically emit light through the light source control circuit. The optical signal generated by at least one path of light source and passing through the physiological tissue is collected through the signal receiving circuit, the collected optical signal is converted into an electric signal, and the amplified electric signal is sampled and quantized. Through the first filtering module, noise parts in the electric signals are filtered, and aliasing interference of the noise parts in the electric signals to non-noise parts in the electric signals is reduced. The electric signal processed by the first filtering module is demodulated through the signal processing module to obtain a digital sampling signal containing at least one physiological characteristic. And calculating to obtain at least one physiological parameter according to the digital sampling signal through a signal processing module. Through the embodiment of the application, the weak perfusion performance and the ambient light interference resistance performance of blood oxygen measurement can be improved, and the accuracy of the blood oxygen measurement system in measuring physiological parameters is improved.
In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present application, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.
FIG. 1 is a schematic view of an oximetry probe unit provided herein;
FIG. 2 is a schematic diagram of an oximetry system provided herein;
FIG. 3 is a schematic flow chart diagram of a blood oxygenation measurement method provided herein;
FIGS. 4A-4G are schematic signal waveforms illustrating an oximetry method provided herein;
fig. 5 is a schematic diagram of another oximetry system provided herein.
The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are some, but not all, embodiments of the present application. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.
It is to be understood that the terminology used in the embodiments of the present application is for the purpose of describing particular embodiments only, and is not intended to be limiting of the application. As used in the examples of this application and the appended claims, the singular forms "a", "an", and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It should also be understood that the term "and/or" as used herein refers to and encompasses any and all possible combinations of one or more of the associated listed items.
In order to better understand the blood oxygen measuring system and method disclosed in the embodiments of the present application, a description is first given below of an applicable scenario of the embodiments of the present application.
Referring to fig. 1, fig. 1 is a schematic view of an oximetry probe device according to an embodiment of the present application. As shown in fig. 1, the schematic diagram of the apparatus may include at least one light source 1 (including but not limited to infrared light, red light, green light, and/or white light), and a receiving tube 3. The user may place an oximetry site (i.e., the physiological tissue 2) into the device and the oximetry system may measure at least one physiological parameter of the physiological tissue (including but not limited to pulse rate, blood oxygen saturation, perfusion index, pulse tone, and/or photoplethysmography). Wherein, at least one path of light source 1 can be used for sending optical signals, and the difference of the absorption coefficients of the oxygenated hemoglobin and the reduced hemoglobin of blood in physiological tissues to the optical signals is large. The blood oxygen measuring method disclosed in the present application can analyze the waveform of the electrical signal excited by the optical signal transmitted through the physiological tissue received by the receiving tube 3 according to the difference, so as to calculate at least one physiological parameter (including pulse rate, blood oxygen saturation, perfusion index, pulse sound and/or photoplethysmography, etc.) of the physiological tissue.
In fact, when measuring the blood oxygen saturation, it cannot be guaranteed that the measurement site is completely in the sealed space, the ambient light may irradiate on the receiving tube 3, and interfere the first signal and the second signal with the electrical signal generated on the receiving tube 3 by penetrating through the physiological tissue, which affects the accuracy of measuring at least one physiological parameter, and causes trouble to clinical medicine, and even causes medical accidents if the medical staff misjudges the result based on the inaccurate result.
Therefore, the blood oxygen measuring system and the blood oxygen measuring method can filter the interference of the ambient light in the blood oxygen measuring process and improve the accuracy of blood oxygen measurement.
The blood oxygen measuring system and method provided by the present application will be described in detail by several embodiments.
Referring to fig. 2, which is a schematic structural diagram of an oximetry system provided in the present application, as shown in fig. 2, the oximetry system 100 may include: the device comprises a light source control circuit 1010, at least one light source 1020, a signal receiving circuit 1030, a first filtering module 1040, a signal processing module 1050, a controller 1060, an output device 1070, a memory 1080, a second filtering module 1090 and at least one communication bus 1100. Wherein the content of the first and second substances,
the light source control circuit 1010 may be connected to the at least one light source 1020 and configured to control the at least one light source 1020 to emit light periodically.
Optionally, the light source control circuit 1010 is further configured to adjust a driving current value required for light emission, a driving voltage value required for light emission, a light emission pulse width, and/or a light emission frequency of at least one light source.
The at least one light source 1020 may include an optical signal emitter embedded in the oximetry probe, with the at least one light source 1020 including, but not limited to, infrared light, red light, green light, and/or white light. For example, the at least one light source 1020 may be an infrared light source and a red light source, and the light source control circuit 1010 may control the two light sources to alternately emit light periodically. The examples are merely illustrative of the present application and should not be construed as limiting.
The signal receiving circuit 1030 may be configured to collect the optical signal generated by the at least one light source and passing through the physiological tissue. The collected optical signals comprise optical signals in the light-emitting period and optical signals in the non-light-emitting period of the at least one path of light source. The signal receiving circuit 1030 may also be configured to convert the collected optical signal into an electrical signal, and sample and quantize the amplified electrical signal; the electric signal contains at least one physiological characteristic information of the physiological tissue;
the signal receiving circuit 1030 may include, but is not limited to, an optical signal acquisition circuit, a photoelectric conversion circuit, and the like. Wherein the content of the first and second substances,
the optical signal collection circuit may be configured to collect an optical signal generated by the at least one light source 1020 and passing through a physiological tissue. The collected optical signals are used for representing the optical signals in the light emitting period and the optical signals in the non-light emitting period of the at least one path of light source.
A photoelectric conversion circuit may be used to convert the collected optical signals into electrical signals. The electrical signal contains at least one physiological characteristic information of the physiological tissue.
The first filtering module 1040 may be coupled to the signal receiving circuit 1030 via a communication bus 1100. The first filtering module 1040 may be used to filter noise portions of the electrical signal.
Specifically, the first filtering module 1040 may be specifically configured to filter ambient light noise and circuit random noise in the electrical signal before demodulating the electrical signal, and reduce aliasing interference of the ambient light noise in the electrical signal on a non-noise portion in the electrical signal.
The first filtering module 1040 may include a low-pass filtering module. The first filtering cut-off frequency of the low-pass filtering module comprises 2 times or more than 2 times of the periodic light-emitting frequency of the at least one path of light source.
And the low-pass filtering module can be used for filtering noise parts in the electric signal beyond the first filtering cut-off frequency before demodulating the electric signal, and eliminating aliasing interference of ambient light noise in the electric signal on non-noise parts in the electric signal.
Optionally, the first filtering module 1040 may further include a low-pass filtering module and a high-pass filtering module, where a second filtering cutoff frequency of the high-pass filtering module includes half or less than half of the periodic light emitting frequency of the at least one light source. A high pass filtering module operable to filter noise portions of the electrical signal outside the second filter cutoff frequency prior to demodulating the electrical signal.
Optionally, the first filtering module 1040 may include a band-pass filtering module, an upper cut-off frequency of the band-pass filtering module includes 2 times or more of the periodic light-emitting frequency of the at least one light source, and a lower cut-off frequency of the band-pass filtering module includes half or less of the periodic light-emitting frequency of the at least one light source. And the band-pass filtering module can be used for filtering the upper cut-off frequency of the band-pass filtering module to the noise part of the electric signal beyond the lower cut-off frequency of the band-pass filtering module before demodulating the electric signal, and eliminating aliasing interference generated by ambient light noise in the electric signal on the non-noise part of the electric signal.
In oximetry system 100, the noise component of the electrical signal includes ambient light noise and circuit random noise having a frequency outside the pass band of the first filtering module; ambient light noise includes, but is not limited to, light-induced noise signals emitted by one or more light sources operating with an ac power source in the ambient environment of the system at a frequency N times the power frequency, N being a positive integer greater than 1;
the aliasing interference is used for representing a physical phenomenon that a noise part in the electric signal generates irreversible frequency distortion after being demodulated by the signal processing module and falls into a physiological bandwidth wholly or partially; the physiological bandwidth is used to characterize a frequency range of the physiological signal; the physiological signal is used for characterizing the signal caused by the periodic change of the blood layer thickness in the physiological tissue caused by the pulse beat.
In the blood oxygen measuring system 100, the non-noise part of the electrical signal is a physiological signal or a signal modulated by the physiological signal and having a frequency within the pass band of the first filtering module; the physiological signal is used for characterizing the signal caused by the periodic change of the blood layer thickness in the physiological tissue caused by the pulse beat.
The signal processing module 1050 may include a Modem (Modem), etc. The signal processing module 1050 may be connected to the first filtering module 1040, and may be configured to demodulate the electrical signal processed by the first filtering module to obtain a digital sampled signal containing at least one physiological characteristic. The digitally sampled signal may include signal characteristics of non-noise portions of the electrical signal.
Optionally, the blood oxygen system measurement system 100 may further include a second filtering module 1090. The second filtering module 1090 may be configured to filter a noise portion of the digital sampling signal obtained by the signal processing module. The noise portion of the digital sampled signal includes, but is not limited to, ambient light noise, circuit random noise and/or circuit interference at frequencies outside of the physiological bandwidth; the physiological bandwidth is used to characterize the frequency range of the physiological signal used to characterize the signal caused by the periodic variation of the blood layer thickness in the physiological tissue due to the pulse beat.
The controller 1060 may be a Central Processing Unit (CPU), and the Processor may be other general purpose Processor, a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), an off-the-shelf Programmable Gate Array (FPGA) or other Programmable logic device, discrete Gate or transistor logic device, discrete hardware component, or the like. The general purpose processor may be a Micro Control Unit (MCU) or the processor may be any conventional processor, etc. The controller 1060 may be configured to calculate at least one physiological parameter from the digital sampled signal. The at least one physiological parameter includes, but is not limited to, pulse rate, blood oxygen saturation, perfusion index, pulse tone, and/or photoplethysmography.
The memory 1080 is coupled to the controller 1060 for storing instructions for the oximetry system. In particular implementations, memory 1080 may include high-speed random access memory and may also include non-volatile memory, such as one or more magnetic disk storage devices, flash memory devices, or other non-volatile solid-state storage devices.
It should be understood that oximetry system 100 is only one example provided by embodiments of the present invention and that oximetry system 100 may have more or less components than those shown, may combine two or more components, or may have a different configuration implementation of components.
Referring to fig. 2, a schematic flow chart of a blood oxygen measurement method is provided, and as shown in fig. 3, the method may include, but is not limited to, the following steps: S301-S306.
S301, controlling at least one path of light source to periodically emit light.
Specifically, at least one light source in the blood oxygen measurement system control periodically emits light, and the light emitting frequency of at least one light source may be 100Hz, 105Hz, 200Hz, and the like, which is not limited herein.
The at least one light source may include, but is not limited to, infrared light, red light, green light, and/or white light. For example, the at least one light source of the blood oxygen measuring system may be one infrared light and one red light, and may also be only one red light, and the examples are only for explaining the present application and should not be construed as limiting.
S302, collecting optical signals which are generated by the at least one path of light source and pass through physiological tissues.
Specifically, as shown in fig. 1, the oximetry system can collect the optical signal generated by the probe portion 1 (at least one light source) and passing through the physiological tissue at the portion 3 (i.e. receiving tube) of the oximetry probe.
The optical signals collected by the blood oxygen measuring system can include optical signals during the light emitting period and optical signals during the non-light emitting period of at least one light source. If at least one light source of the blood oxygen measuring system can be red light and infrared light, the blood oxygen measuring system controls the red light and the infrared light to periodically and alternately emit light, and the light signals acquired by the blood oxygen measuring system have four stages. This is illustrated below in conjunction with fig. 4A.
As shown in fig. 4A, when the blood oxygen measuring system controls the periodic alternate emission of red light and infrared light, the four phases of the light signal collected by the blood oxygen measuring system may include: a red light emitting stage (stage B), a red light non-emitting stage (stage A), an infrared light emitting stage (stage D), and an infrared light non-emitting stage (stage C). Wherein:
the red light emission stage (B stage) may be a stage in which the physiological tissue is irradiated with red light emission;
the red light non-luminous stage (stage A) can be a stage from the end of irradiation of the physiological tissue by the infrared light to the beginning of irradiation of the physiological tissue by the red light;
the infrared light emission stage (stage D) may be a stage in which the physiological tissue is irradiated with infrared light emission;
the infrared light non-emission period (C period) may be a period from the end of irradiation of the tissue with the red light to the start of irradiation of the tissue with the infrared light.
Fig. 4A is merely illustrative of the present application and should not be construed as limiting.
And S303, converting the collected optical signals into electric signals.
In particular, the oximetry system may convert the collected light signals into electrical signals. The electrical signal may be a current signal or a voltage signal, and is not limited herein.
After the optical signal is converted into the electrical signal, the electrical signal is weak, and the circuit component is difficult to identify the characteristic information (such as amplitude, frequency and the like) of the voltage signal. The oximetry system may amplify and compensate the voltage signal. For example, assuming that the electrical signal is a voltage signal, the amplitude of the voltage signal photoelectrically converted by the oximetry system may be 0.002V, and after the amplification compensation is performed to 100 times, the first amplitude of the voltage signal may be amplified to 0.2V. The examples are merely illustrative of the present application and should not be construed as limiting.
In a specific implementation, the blood oxygen measuring system can perform analog-to-digital conversion on the amplified and compensated electric signal, and sample and quantize the electric signal. The sampled and quantized electrical signal contains at least one physiological characteristic information (such as blood oxygen saturation, pulse rate, etc.) of the physiological tissue.
Optionally, the blood oxygen measuring system may adjust a driving current value, a driving voltage value, a light emitting pulse width, and/or a light emitting frequency required for light emission of the at least one light source according to the collected light signal.
In some possible cases, the optical signal collector in the receiving tube on the blood oxygen measuring probe may generate different transient responses to the transient optical signal, the time length for the collected optical signal to reach the stability may be different, and if the time length for the optical signal to reach the stability is longer and the light emitting pulse width of the at least one light source is unchanged, the blood oxygen system may not sample the stable electrical signal value, which may cause the accuracy of the blood oxygen system to measure the at least one physiological parameter of the physiological tissue to decrease.
For the above situation, the oximetry system may detect the time at which the aforementioned light signal reaches steady state. Here, the time may be referred to as a first time. After detecting the first time, the blood oxygen system may set the light emitting pulse width of the light signal to a first multiple of the first time.
In the present application, the photocurrent signal may be generated by a first optical signal (in the first light source lighting phase (B phase)), or may be generated by a second optical signal (in the second light source lighting phase (D phase)). The first multiple is at least greater than 1 to ensure that the blood oxygenation system has the possibility of sampling to a stable voltage value.
In one implementation, the oximetry system may detect that the optical signal from the first light source is sent to the first light source collected by the oximetry system for a first time period until the optical signal reaches a stable state. The oximetry system may set the pulse width of the light emitted by the light source to a first multiple of the first time.
In practical application, when the first multiple is 2 times or more than 2 times, the blood oxygen measuring system can ensure that at least half of the time of the light signal is stable within one pulse width of the light source, so that the probability of unstable light signal values acquired by the blood oxygen measuring system can be reduced, and the accuracy of the blood oxygen saturation measuring system in measuring the blood oxygen saturation can be improved. The first multiple may be 2 times, 3 times, 4 times, or higher, and the like, and is not particularly limited herein.
The luminous pulse width of the light source is controlled to be the first multiple of the time for the light source to emit light and the light signal generated by the light source reaches the stable time, so that the probability that the blood oxygen measuring system collects the unstable light signal value can be reasonably reduced, and the accuracy of measuring the blood oxygen can be improved.
S304, filtering noise parts in the electric signal before demodulating the electric signal.
In particular, the noise portion of the electrical signal may include ambient light noise and circuit random noise having frequencies outside of the filter passband. Ambient light noise may include, but is not limited to, noise signals caused by light having a frequency N times the power frequency emitted by one or more light sources operating with an ac power source in the ambient environment of the oximetry system, N being a positive integer greater than 1.
The non-noise portion of the electrical signal may include the physiological signal or a signal modulated by the physiological signal having a frequency within the filter passband. The physiological signal can be used to characterize the signal caused by the periodic variation of the blood layer thickness in the physiological tissue caused by the pulse beat.
Under some possible conditions, the ambient light around the blood oxygen measurement object can generate spectrum aliasing interference after being demodulated, namely, the noise part in the electric signal generates irreversible frequency distortion after being demodulated and falls into the physiological bandwidth in whole or in part, and the accuracy of blood oxygen measurement is influenced.
For example, the aliasing phenomenon is illustrated, and for example, the blue light supplied by 50Hz power frequency is taken as an example, and the light emitted by the blue light lamp contains primary, secondary or multiple harmonics of the power frequency. When the utility grid is unstable, the power frequency will deviate from 50Hz, for example 50.6 Hz. According to the nyquist sampling law, when the frequency of the signal is 2 times higher than the sampling frequency, spectrum aliasing occurs after demodulation. Assuming that the light emitting frequency of the at least one path of light source is 208.33Hz, and when the public power grid is unstable, the 33-frequency doubling harmonic frequency of the blue light power frequency of 50.6Hz is 1669.8Hz, the aliasing frequency can be obtained by aliasing frequency calculation according to the aliasing frequency calculation formula (1) and is 3.13Hz, and the accuracy of measuring the blood oxygen saturation can be influenced when the frequency after aliasing is within a physiological bandwidth (0-5 Hz). Wherein, the calculation formula of aliasing frequency is the following formula (1):
fa ═ abs (f-n ═ Fs) formula (1)
In the above formula (1), abs is an absolute value, f is an actual frequency of a signal before aliasing (i.e., a frequency doubling harmonic frequency 1669.8Hz of a blue light power frequency 33), Fs is a light emitting frequency of at least one light source (i.e., 208.33Hz), n is Int (f/Fs +0.5), wherein Int is an integer operation, only an integer part before a decimal point is reserved, and fa is a frequency after aliasing (3.13 Hz).
In response to the above situation, the oximetry system may utilize low-pass filtering to filter noise components in the electrical signal outside the first filtering cutoff frequency of the low-pass filtering, and reduce aliasing interference of the noise components in the electrical signal to non-noise components in the electrical signal. The first filtering cut-off frequency comprises 2 times or more than 2 times of the periodic light emitting frequency of the at least one path of light source.
Oximetry systems may also utilize high pass filtering that filters noise portions of the electrical signal outside of the second cut-off frequency of the high pass filtering. The second filtering cut-off frequency comprises half or less of the periodic light-emitting frequency of the at least one path of light source.
In the above example, after the low-pass filtering with the first filtering cut-off frequency being 2 times or more than 2 times (for example, 420Hz) of the periodic light emitting frequency (208.33Hz) of the at least one light source is utilized, the harmonic of the frequency of 33 times (with the frequency of 1669.8Hz) and higher times of the power frequency 50.6Hz of the blue light lamp is filtered out, that is, the aliasing waveform of 3.13Hz does not occur. When the high-pass filtering with the second filtering cut-off frequency being half or less than half of the periodic light emitting frequency of at least one path of light source is utilized, the noise part in the electric signals outside the second cut-off frequency can be filtered, so that the blood oxygen measuring accuracy can be improved.
Optionally, for the above aliasing interference situation, the oximetry system may utilize band-pass filtering to filter a noise portion in the electrical signal from an upper cut-off frequency of the band-pass filtering to a lower cut-off frequency of the band-pass filtering, so as to reduce aliasing interference generated by the noise portion in the electrical signal on a non-noise portion in the electrical signal. The upper cut-off frequency of the band-pass filter comprises 2 times or more than 2 times of the periodic light-emitting frequency of the at least one path of light source, and the lower cut-off frequency of the band-pass filter comprises half or less than half of the periodic light-emitting frequency of the at least one path of light source.
When the upper cut-off frequency of the band-pass filter is 2 times or more than 2 times (such as 420Hz) of the periodic light-emitting frequency (208.33Hz) of at least one path of light source, and the lower cut-off frequency of the band-pass filter comprises half or less than half (such as 100Hz) of the periodic light-emitting frequency of the at least one path of light source, 33 frequency-doubled harmonic (with the frequency of 1669.8Hz) and higher harmonic of the blue light power frequency of 50.6Hz can be filtered, namely 3.13Hz aliasing waveform can not occur. When the band-pass filter with the cut-off frequency being half or less than half of the periodic light-emitting frequency of at least one path of light source is utilized, the noise part in the electric signal outside the second cut-off frequency can be filtered, and the aliasing interference of the ambient light noise to the non-noise part in the electric signal is reduced, so that the accuracy of the blood oxygen measuring system for measuring the physiological parameters can be improved.
The examples are merely illustrative of the present application and should not be construed as limiting.
The beneficial effects after filtering in step S304 can be further explained with reference to fig. 4B, 4C, 4D, and 4E.
Fig. 4B is a time-domain waveform diagram of the electrical signal without being filtered in step S304 after being interfered by 1669.8Hz ambient light. As shown in fig. 4B, the waveform is severely distorted due to the disturbance of the ambient light. Fig. 4C is a frequency domain waveform diagram of the electrical signal without being filtered in step S304 after being interfered by 1669.8Hz ambient light. As shown in FIG. 4C, the aliasing frequency peak of the ambient light interference at 3.13Hz, which is within the physiological bandwidth (0.3Hz-5Hz), affects the accuracy of the oximetry system in measuring the physiological parameters.
Fig. 4D is a time domain waveform diagram of the electrical signal subjected to 1669.8Hz ambient light interference, but filtered in step S304. As shown in fig. 4D, in comparison with fig. 4B, the distortion of the waveform of the electrical signal caused by the ambient light interference is greatly reduced, and the physiological signal characteristics are obvious. Fig. 4E is a spectrum diagram of the waveform of the electrical signal filtered in step S304. As shown in fig. 4E, the spectrogram of the electrical signal waveform significantly attenuates the ambient light interference aliasing frequency as compared to fig. 4C.
As can be seen from the above figure, by filtering the noise part in the electrical signal, the aliasing interference of the ambient light noise of the electrical signal to the non-noise part in the electrical signal is reduced, and the accuracy of the blood oxygen measuring system for measuring the physiological parameter can be improved.
The above examples are merely illustrative of the present application and should not be construed as limiting.
The beneficial effect of filtering the circuit random noise in the electrical signal by the first filtering module can be further explained with reference to fig. 4F and 4G.
Fig. 4F is a time domain waveform diagram of the electrical signal that is only disturbed by random noise in the circuit. As shown in fig. 4F, due to the interference of the random noise of the circuit, the time domain waveform of the electrical signal is severely distorted, which may affect the accuracy of the blood oxygen measurement system for measuring the physiological parameter.
Fig. 4G is a time domain waveform diagram of the electrical signal after the first filtering module filters part of the circuit random noise in the electrical signal. As shown in fig. 4G, compared with fig. 4F, the distortion of the time domain waveform of the electrical signal is greatly reduced, and the physiological signal characteristics are obvious.
As can be seen from the above figure, the accuracy of the blood oxygen measuring system for measuring the physiological parameter can be improved by filtering the circuit random noise in the electric signal through the first filtering module.
The examples are merely illustrative of the present application and should not be construed as limiting.
S305, demodulating the electric signal after the noise part is filtered, and obtaining a digital sampling signal containing at least one physiological characteristic.
Specifically, the oximetry system performs signal demodulation on the electric signal after the noise part is filtered through a demodulator, so as to obtain a digital sampling signal containing at least one physiological characteristic. The at least one physiological characteristic may include a pulse rate characteristic, a blood oxygen saturation characteristic, and other physiological characteristics of the physiological tissue, which are not limited herein.
In some possible cases, after the blood oxygen measurement system obtains the digital sampling signal, the digital sampling signal may still be interfered by ambient light noise with frequency outside the physiological bandwidth, circuit random noise and/or circuit power frequency interference.
For the above situation, the blood oxygen system may filter the noise part of the digital sampling signal after acquiring the digital sampling signal. The noise part of the digital sampling signal includes, but is not limited to, the above-mentioned ambient light noise with a frequency outside the physiological bandwidth, circuit random noise and/or circuit power frequency interference. The physiological bandwidth can be used to characterize a frequency range of a physiological signal, which can be a signal due to a periodic variation in blood layer thickness within the physiological tissue caused by pulse beats in the physiological tissue.
The blood oxygen measuring system can filter the digital sampling signal through the second filtering module, and the noise part in the digital sampling signal is filtered. The filtering module may be a high-pass filter, a low-pass filter, and/or a band-pass filter, and is not limited herein. For example, the physiological bandwidth may be 0.3Hz-5Hz, and the blood oxygen system may utilize a second low pass filter, which has a cut-off frequency set to 5.5Hz, so as to filter the noise portion of the digital sampling signal with a frequency greater than 5.5 Hz. The blood oxygen system can also utilize a second high-pass filter, and the cut-off frequency of the second high-pass filter is set to be 0.2Hz, so that the noise part with the frequency less than 0.2Hz in the digital sampling signal can be filtered. The blood oxygen system may also utilize a second band-pass filter, the second band-pass filter having a passband set to 0.2Hz-5.5Hz, thereby filtering noise components of the digital sampled signal having frequencies outside of 0.2Hz-5.5 Hz.
The examples are merely illustrative of the present application and should not be construed as limiting.
The blood oxygen system obtains the digital sampling signal by demodulating the voltage signal after the noise part is filtered, filters the noise part in the digital sampling signal, can improve the signal-to-noise ratio of the digital sampling signal, and improves the accuracy of the blood oxygen measurement system in measuring the blood oxygen.
And S306, calculating to obtain at least one physiological parameter according to the digital sampling signal.
Specifically, the blood oxygen measuring system can calculate at least one physiological parameter according to the obtained digital sampling signal. The at least one physiological parameter may include pulse rate, blood oxygen saturation, perfusion index, pulse sound, photoplethysmography, and/or the like, but is not limited thereto.
Optionally, the oximetry system outputs a first prompt, which may be used to prompt the at least one physiological parameter (e.g., pulse rate, blood oxygen saturation, perfusion index, pulse tone, photoplethysmogram, etc.). The first prompt may be a sound prompt for displaying the at least one physiological parameter through a display screen, or an audio prompt for outputting a sound effect of the at least one physiological parameter through an audio device.
The blood oxygen measuring system may also set a respective risk threshold for the at least one physiological parameter, and when the risk threshold is reached in the at least one physiological parameter calculated by the blood oxygen measuring system, a second prompt may be output for prompting the user that the physiological parameter is in a dangerous condition. Therefore, the change condition of the physiological parameters of the detected user can be conveniently paid attention to at any time, and the medical effect is improved.
Through the embodiment of the application, the blood oxygen measuring system can filter the noise part in the electric signal, aliasing interference of high-frequency harmonic waves of ambient light noise on the non-noise part in the electric signal is greatly reduced, and the accuracy of the blood oxygen measuring system in measuring physiological parameters is improved.
Referring to fig. 5, which is a schematic structural diagram of another blood oximetry system provided in the present application, as shown in fig. 5, the blood oximetry system 50 may include: a control unit 510, an acquisition unit 520, a conversion unit 530, a first filtering unit 540, a processing unit 550 and an arithmetic unit 570. Wherein the content of the first and second substances,
the control unit 510 may be configured to control at least one light source to emit light periodically. Wherein the at least one light source includes, but is not limited to, infrared light, red light, green light, and/or white light.
The collecting unit 520 may be configured to collect the optical signal generated by the at least one light source and passing through the physiological tissue. The collected optical signals are used for including optical signals in the light-emitting period and optical signals in the non-light-emitting period of the at least one path of light source.
A conversion unit 530 operable to convert the collected optical signal into an electrical signal. The electrical signal contains at least one physiological characteristic information of the physiological tissue.
A first filtering unit 540 operable to filter a noise portion of the electrical signal before demodulating the electrical signal;
in particular, the first filtering unit 540 may be specifically configured to filter a noise portion in the electrical signal before demodulating the electrical signal, so as to reduce aliasing interference, which is generated by ambient light noise in the electrical signal, on a non-noise portion in the electrical signal.
The first filtering unit 540 may specifically include a low-pass filtering subunit. And the low-pass filtering subunit is used for filtering noise parts in the electric signal beyond a first filtering cut-off frequency of the low-pass filtering before demodulating the electric signal by using the low-pass filtering, and eliminating aliasing interference of ambient light noise in the electric signal on non-noise parts in the electric signal. The first filtering cut-off frequency comprises 2 times or more than 2 times of the periodic light emitting frequency of the at least one path of light source.
Optionally, the first filtering unit 540 may further include a low-pass filtering subunit and a high-pass filtering subunit.
The high-pass filtering subunit can filter a noise part in the electric signal outside a second filtering cut-off frequency of the high-pass filtering by using the high-pass filtering. The second filtering cut-off frequency comprises half or less of the periodic light-emitting frequency of the at least one path of light source.
Optionally, the first filtering unit 540 may specifically include a band-pass filtering subunit.
And the band-pass filtering subunit is used for filtering a noise part in the electric signal from the upper cut-off frequency of the band-pass filtering to the position outside the lower cut-off frequency of the band-pass filtering before demodulating the electric signal by using the band-pass filtering, and reducing aliasing interference generated by ambient light noise in the electric signal on a non-noise part in the electric signal. The upper cut-off frequency of the band-pass filter comprises 2 times or more than 2 times of the periodic light-emitting frequency of the at least one path of light source, and the lower cut-off frequency of the band-pass filter comprises half or less than half of the periodic light-emitting frequency of the at least one path of light source.
A processing unit 550 is operable to demodulate the electrical signal after filtering the noise portion to obtain a digital sampled signal containing at least one physiological characteristic. The digital sampled signal contains signal characteristics of non-noise portions of the electrical signal.
And the arithmetic unit 570 is used for calculating at least one physiological parameter according to the digital sampling signal. The at least one physiological parameter includes, but is not limited to, pulse rate, blood oxygen saturation, perfusion index, pulse sound, and/or photoplethysmography.
Optionally, the blood oxygen measuring system 50 may further comprise a second filtering unit 560, wherein the noise part of the digital sampling signal obtained by the processing unit 550 is filtered.
Wherein the noise part of the digital sampling signal comprises but is not limited to ambient light noise with frequency outside physiological bandwidth, circuit random noise and/or circuit power frequency interference; the physiological bandwidth is used for characterizing a frequency range of the physiological signal, and the physiological signal is used for characterizing a signal caused by the periodic change of the blood layer thickness in the physiological tissue caused by the pulse beat.
Optionally, the blood oxygen measuring system 50 may further include an adjusting unit for adjusting a driving current required for the at least one light source to emit light, a driving voltage value required for the at least one light source to emit light, a light emitting pulse width, and/or a light emitting frequency.
Specifically, in the blood oximetry system 50 of the embodiments of the present application, the noise component in the electrical signal includes ambient light noise and circuit random noise with frequencies outside the filter passband. The ambient light noise includes, but is not limited to, a noise signal caused by light having a frequency N times the power frequency emitted by one or more light sources operating with an ac power source in the ambient environment of the system, where N is a positive integer greater than 1.
The non-noise part in the electric signal comprises a physiological signal or a signal with the frequency within a filtering passband after being modulated by the physiological signal; the physiological signal is used for characterizing the signal caused by the periodic change of the blood layer thickness in the physiological tissue caused by the pulse beat.
The aliasing interference is used for representing the physical phenomenon that the noise part in the electric signal generates irreversible frequency distortion after being demodulated and falls into the physiological bandwidth wholly or partially. The physiological bandwidth is used to characterize a frequency range of the physiological signal; the physiological signal is used for characterizing the signal caused by the periodic change of the blood layer thickness in the physiological tissue caused by the pulse beat.
In the oximetry system 50 of the embodiments of the present application, the at least one physiological parameter includes, but is not limited to, pulse rate, blood oxygen saturation, perfusion index, pulse tone, and/or photoplethysmography.
It is understood that specific implementations of the various functional units included in the system 50 can refer to the foregoing method embodiment (shown in fig. 3), and are not described herein again.
In another embodiment of the present application, a computer-readable storage medium is provided, which stores a computer program that, when executed by a processor, implements the method of fig. 2 described above.
The computer readable storage medium may be an internal storage unit of the system according to any of the foregoing embodiments, for example, a hard disk or a memory of the system. The computer readable storage medium may also be an external storage device of the system, such as a plug-in hard drive, Smart Media Card (SMC), Secure Digital (SD) Card, Flash memory Card (Flash Card), etc. provided on the system. Further, the computer readable storage medium may also include both an internal storage unit and an external storage device of the oximetry system. The computer readable storage medium is used to store the computer program and other programs and data required by the blood oximetry system. The computer readable storage medium may also be used to temporarily store data that has been output or is to be output.
Those of ordinary skill in the art will appreciate that the elements and algorithm steps of the examples described in connection with the embodiments disclosed herein may be embodied in electronic hardware, computer software, or combinations of both, and that the components and steps of the examples have been described in a functional general in the foregoing description for the purpose of illustrating clearly the interchangeability of hardware and software. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the implementation. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present application.
It is clear to those skilled in the art that, for convenience and brevity of description, the specific working processes of the above-described systems and units may refer to the corresponding processes in the foregoing method embodiments, and are not described herein again.
In the several embodiments provided in the present application, it should be understood that the disclosed method and system may be implemented in other ways. For example, the above-described embodiments of systems and apparatuses are merely illustrative, and for example, the division of the units is only one logical division, and there may be other divisions when actually implemented, for example, a plurality of units or components may be combined or may be integrated into another system, or some features may be omitted, or not executed. In addition, the shown or discussed mutual coupling or direct coupling or communication connection may be an indirect coupling or communication connection through some interfaces, devices or units, and may also be an electric, mechanical or other form of connection.
The units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the scheme of the application.
In addition, functional units in the embodiments of the present application may be integrated into one processing unit, or each unit may exist alone physically, or two or more units are integrated into one unit. The integrated unit can be realized in a form of hardware, and can also be realized in a form of a software functional unit.
The integrated unit, if implemented in the form of a software functional unit and sold or used as a stand-alone product, may be stored in a computer readable storage medium. Based on such understanding, the technical solution of the present application may be substantially or partially contributed by the prior art, or all or part of the technical solution may be embodied in a software product, which is stored in a storage medium and includes instructions for causing a computer device (which may be a personal computer, a server, or a network device) to execute all or part of the steps of the method according to the embodiments of the present application. And the aforementioned storage medium includes: a U-disk, a removable hard disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), a magnetic disk or an optical disk, and other various media capable of storing program codes.
While the invention has been described with reference to specific embodiments, the scope of the invention is not limited thereto, and those skilled in the art can easily conceive various equivalent modifications or substitutions within the technical scope of the invention. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.
Claims (27)
- An oximetry system, comprising: the device comprises at least one path of light source, a light source control circuit, a signal receiving circuit, a first filtering module, a signal processing module and a controller;the light source control circuit is used for controlling the at least one path of light source to periodically emit light;the signal receiving circuit is used for collecting optical signals which are generated by the at least one path of light source and pass through physiological tissues; the collected optical signals comprise optical signals in a light-emitting period and optical signals in a non-light-emitting period of the at least one path of light source;the signal receiving circuit is also used for converting the collected optical signals into electric signals; the electric signal contains at least one physiological characteristic information of the physiological tissue;the first filtering module is used for filtering a noise part in the electric signal before demodulating the electric signal;the signal processing module is used for demodulating the electric signal processed by the first filtering module to obtain a digital sampling signal containing at least one physiological characteristic; the digital sampled signal contains signal characteristics of a non-noise portion of the electrical signal;the controller is used for calculating at least one physiological parameter according to the digital sampling signal.
- The system of claim 1, wherein the noise component of the electrical signal comprises ambient light noise and circuit random noise having a frequency outside of the pass band of the first filtering module;the first filtering module is specifically configured to:and filtering ambient light noise and circuit random noise in the electric signal before demodulating the electric signal, and eliminating aliasing interference of the ambient light noise in the electric signal to a non-noise part in the electric signal.
- The system of claim 2, wherein the ambient light noise includes, but is not limited to, a noise signal due to light of frequency N times power frequency emitted by one or more light sources operating with an ac power source in the ambient environment of the system, N being a positive integer greater than 1;the aliasing interference is used for representing a physical phenomenon that a noise part in the electric signal generates irreversible frequency distortion after being demodulated by the signal processing module and falls into a physiological bandwidth wholly or partially; the physiological bandwidth is used to characterize a frequency range of the physiological signal; the physiological signal is used for characterizing the signal caused by the periodic change of the blood layer thickness in the physiological tissue caused by the pulse beat.
- The system of any of claims 1-3, wherein the first filtering module comprises a low pass filtering module; the first filtering cut-off frequency of the low-pass filtering module comprises 2 times or more of the periodic light-emitting frequency of the at least one path of light source;the low-pass filtering module is used for filtering noise parts in the electric signal beyond the first filtering cut-off frequency before demodulating the electric signal.
- The system of claim 4, wherein the first filtering module further comprises a high-pass filtering module; the second filtering cut-off frequency of the high-pass filtering module is half or less than the periodic light-emitting frequency of the at least one path of light source;the high-pass filtering module is used for filtering noise parts in the electric signal beyond the second filtering cut-off frequency before demodulating the electric signal.
- The system of any of claims 1-3, wherein the first filtering module comprises a band pass filtering module; the upper cut-off frequency of the band-pass filter module comprises 2 times or more of the periodic light-emitting frequency of the at least one path of light source, and the lower cut-off frequency of the band-pass filter module comprises half or less of the periodic light-emitting frequency of the at least one path of light source;the band-pass filtering module is used for filtering the upper cut-off frequency of the band-pass filtering module to the noise part of the electric signal beyond the lower cut-off frequency of the band-pass filtering module before demodulating the electric signal.
- The system according to claim 2, wherein the non-noise part of the electrical signal is a physiological signal or a signal modulated by the physiological signal and having a frequency within a pass band of the first filtering module; the physiological signal is used for characterizing the signal caused by the periodic change of the blood layer thickness in the physiological tissue caused by the pulse beat.
- The system of claim 1, further comprising:the second filtering module is used for filtering the noise part of the digital sampling signal obtained by the signal processing module; the noise part of the digital sampling signal comprises but is not limited to ambient light noise with frequency outside physiological bandwidth, circuit random noise and/or circuit power frequency interference; the physiological bandwidth is used for characterizing a frequency range of the physiological signal, and the physiological signal is used for characterizing a signal caused by the periodic change of the blood layer thickness in the physiological tissue caused by the pulse beat.
- The system of claim 1, wherein the at least one physiological parameter includes, but is not limited to, pulse rate, blood oxygen saturation, perfusion index, pulse sounds, and/or photoplethysmography;the at least one light source includes, but is not limited to, infrared light, red light, green light and/or white light;the light source control circuit is further configured to adjust a driving current required by the at least one path of light source to emit light, a driving voltage value required by the at least one path of light source to emit light, a light emitting pulse width and/or a light emitting frequency.
- A method of oximetry comprising:controlling at least one path of light source to periodically emit light;collecting optical signals which are generated by the at least one path of light source and pass through physiological tissues; the collected optical signals comprise optical signals in a light-emitting period and optical signals in a non-light-emitting period of the at least one path of light source;converting the collected optical signals into electrical signals; the electric signal contains at least one physiological characteristic information of the physiological tissue;filtering a noise portion of the electrical signal prior to demodulating the electrical signal;demodulating the electrical signal after filtering the noise portion to obtain a digital sampled signal containing at least one physiological characteristic; the digital sampled signal contains signal characteristics of a non-noise portion of the electrical signal;and calculating at least one physiological parameter according to the digital sampling signal.
- The method of claim 10, wherein the noise component of the electrical signal comprises ambient light noise and circuit random noise having a frequency outside the filter passband;the filtering the noise part in the electrical signal before demodulating the electrical signal specifically includes:and filtering ambient light noise and circuit random noise in the electric signal before demodulating the electric signal, and eliminating aliasing interference of the ambient light noise in the electric signal to a non-noise part in the electric signal.
- The method of claim 11, wherein the ambient light noise includes, but is not limited to, a noise signal due to light of frequency N times power frequency emitted by one or more light sources operating with an ac power source in the ambient environment of the system, N being a positive integer greater than 1;the aliasing interference is used for representing a physical phenomenon that a noise part in the electric signal is subjected to irreversible frequency distortion after being demodulated and falls into a physiological bandwidth wholly or partially; the physiological bandwidth is used to characterize a frequency range of the physiological signal; the physiological signal is used for characterizing the signal caused by the periodic change of the blood layer thickness in the physiological tissue caused by the pulse beat.
- The method according to any of claims 10 to 12, wherein said filtering the noise portion of the electrical signal before demodulating the electrical signal comprises:filtering, with low-pass filtering, a noise portion of the electrical signal outside a first filter cutoff frequency of the low-pass filtering prior to demodulation; the first filtering cut-off frequency comprises 2 times or more than 2 times of the periodic light emitting frequency of the at least one path of light source.
- The method according to claim 13, wherein filtering noise components of the electrical signal prior to demodulating the electrical signal, further comprises:filtering, with high-pass filtering, noise portions in the electrical signal outside a second cut-off frequency of the high-pass filtering before demodulating the electrical signal; the second filtering cut-off frequency comprises half or less of the periodic light-emitting frequency of the at least one path of light source.
- The method according to any of claims 10 to 12, wherein said filtering the noise portion of the electrical signal before demodulating the electrical signal comprises:filtering, with band-pass filtering, a noise portion in the electrical signal outside of an upper cutoff frequency of the band-pass filtering to a lower cutoff frequency of the band-pass filtering before demodulating the electrical signal;the upper cut-off frequency of the band-pass filter comprises 2 times or more than 2 times of the periodic light-emitting frequency of the at least one path of light source, and the lower cut-off frequency of the band-pass filter comprises half or less than half of the periodic light-emitting frequency of the at least one path of light source.
- The method of claim 11, wherein the non-noise portion of the electrical signal comprises a physiological signal or a signal modulated by a physiological signal and having a frequency within a filter passband; the physiological signal is used for characterizing the signal caused by the periodic change of the blood layer thickness in the physiological tissue caused by the pulse beat.
- The method of claim 10, further comprising:filtering a noise portion of the digitally sampled signal; the noise part of the digital sampling signal comprises but is not limited to ambient light noise with frequency outside physiological bandwidth, circuit random noise and/or circuit power frequency interference; the physiological bandwidth is used for characterizing a frequency range of the physiological signal, and the physiological signal is used for characterizing a signal caused by the periodic change of the blood layer thickness in the physiological tissue caused by the pulse beat.
- The method of claim 10, wherein the at least one physiological parameter includes, but is not limited to, pulse rate, blood oxygen saturation, perfusion index, pulse sounds, and/or photoplethysmography;the at least one light source includes, but is not limited to, infrared light, red light, green light and/or white light;the method further comprises the following steps:and adjusting the driving current value, the driving voltage value, the light-emitting pulse width and/or the light-emitting frequency required by the light emission of the at least one path of light source.
- An oximetry system, comprising: the device comprises a control unit, an acquisition unit, a conversion unit, a first filtering unit, a processing unit and an operation unit; wherein the content of the first and second substances,the control unit is used for controlling at least one path of light source to periodically emit light;the acquisition unit is used for acquiring optical signals which are generated by the at least one path of light source and pass through physiological tissues; the collected optical signals comprise optical signals in a light-emitting period and optical signals in a non-light-emitting period of the at least one path of light source;the conversion unit is used for converting the collected optical signals into electric signals; the electric signal contains at least one physiological characteristic information of the physiological tissue;the first filtering unit is used for filtering a noise part in the electric signal before demodulating the electric signal;the processing unit is used for demodulating the electric signal after the noise part is filtered to obtain a digital sampling signal containing at least one physiological characteristic; the digital sampled signal contains signal characteristics of a non-noise portion of the electrical signal;and the arithmetic unit is used for calculating at least one physiological parameter according to the digital sampling signal.
- The system of claim 19, wherein the noise component of the electrical signal comprises ambient light noise and circuit random noise having a frequency outside of a filter passband;the first filtering unit is specifically configured to:and filtering ambient light noise and circuit random noise in the electric signal before demodulating the electric signal, and eliminating aliasing interference of the ambient light noise in the electric signal to a non-noise part in the electric signal.
- The system of claim 20, wherein the ambient light noise includes, but is not limited to, a noise signal due to light of frequency N times power frequency emitted by one or more light sources operating with an ac power source in the ambient environment of the system, N being a positive integer greater than 1;the aliasing interference is used for representing a physical phenomenon that a noise part in the electric signal is subjected to irreversible frequency distortion after being demodulated and falls into a physiological bandwidth wholly or partially; the physiological bandwidth is used to characterize a frequency range of the physiological signal; the physiological signal is used for characterizing the signal caused by the periodic change of the blood layer thickness in the physiological tissue caused by the pulse beat.
- The system according to any one of claims 19 to 21, wherein the first filtering unit is specifically configured to:filtering, with low-pass filtering, a noise portion of the electrical signal outside a first filter cutoff frequency of the low-pass filtering prior to demodulation; the first filtering cut-off frequency comprises 2 times or more of the periodic light emitting frequency of the at least one path of light source.
- The system according to claim 22, wherein the first filtering unit is further configured to:filtering, with high-pass filtering, noise portions in the electrical signal outside a second cut-off frequency of the high-pass filtering before demodulating the electrical signal; the second filtering cut-off frequency comprises half or less of the periodic light-emitting frequency of the at least one path of light source.
- The system according to any of claims 19 to 21, wherein the first filtering unit is specifically configured to:filtering, with band-pass filtering, a noise portion in the electrical signal outside of an upper cutoff frequency of the band-pass filtering to a lower cutoff frequency of the band-pass filtering before demodulating the electrical signal;the upper cut-off frequency of the band-pass filter comprises 2 times or more of the periodic light-emitting frequency of the at least one path of light source, and the lower cut-off frequency of the band-pass filter comprises half or less of the periodic light-emitting frequency of the at least one path of light source.
- The system of claim 20, wherein the non-noise portion of the electrical signal comprises a physiological signal or a signal modulated by a physiological signal and having a frequency within a filter passband; the physiological signal is used for characterizing the signal caused by the periodic change of the blood layer thickness in the physiological tissue caused by the pulse beat.
- The system of claim 19, further comprising:a second filtering unit for filtering a noise part of the digital sampling signal obtained by the processing unit; the noise part of the digital sampling signal comprises but is not limited to ambient light noise with frequency outside physiological bandwidth, circuit random noise and/or circuit power frequency interference; the physiological bandwidth is used for characterizing a frequency range of the physiological signal, and the physiological signal is used for characterizing a signal caused by the periodic change of the blood layer thickness in the physiological tissue caused by the pulse beat.
- The system of claim 19, wherein the at least one physiological parameter includes, but is not limited to, pulse rate, blood oxygen saturation, perfusion index, pulse sounds, and/or photoplethysmography;the at least one light source includes, but is not limited to, infrared light, red light, green light and/or white light;the system, still include:and the adjusting unit is used for adjusting the driving current required by the at least one path of light source to emit light, the driving voltage value required by the light emission, the light emitting pulse width and/or the light emitting frequency.
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| PCT/CN2018/074460 WO2019144406A1 (en) | 2018-01-29 | 2018-01-29 | Blood oxygen measurement system and method |
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