Method and device for measuring venous blood oxygenation
Inventors
Assignees
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Publication Number
US-10398364-B2
Publication Date
2019-09-03
Expiration Date
Abstract
A device for non-invasively measuring at least one parameter of a cardiac blood vessel in a patient comprises at least one light source that directs light at a tissue site on the patient; at least one photodetector adapted to receive light emitted by the light source and generate an output based on the received light, the output of said photodetector being correlated with a parameter of the blood vessel; and at least one probe for facilitating delivery of light from the light source to the tissue site, and receipt of light by the photodetector. The device may include a height sensor to adapt it for use to determine central venous pressure, or the configuration of light source(s) and photodetector(s) may be adapted to permit the device to provide attenuation correction in the determination of venous blood oxygenation.
Core Innovation
The invention provides an optical non-invasive device and method for monitoring venous blood parameters by delivering light in a 400–1000 nm wavelength range near the jugular vein using a patch probe. The device includes at least one light source and at least one photodetector that translates reflected light and/or transmitted light from tissue of a patient into a recordable output. The recordable output is digitized into waveforms for venous blood parameter determination.
A pressure sensor is mounted on the probe and connected to a reference patch compatible for placement on the skin via a tube configured to contain a liquid. The pressure sensor provides a pressure reading useful to determine vertical height from the reference patch to the probe, and the signal processing means calculates central venous pressure from the photodetector output and the pressure reading. The optical waveform is used to derive central venous pulse and/or pressure via waveform amplitude and height along the jugular vein using patient inclination sensors.
The invention further determines venous blood oxygenation using multi-wavelength measurements and Modified Beer Lambert’s Law. Attenuation correction is performed using dual-wavelength source-detector separation differences via an optical attenuation difference and an attenuation correction factor C, integrated into an oximeter-type equation. The document describes multiple probe and sensing configurations and reports improved agreement after attenuation correction.
Claims Coverage
The document’s independent claim covers an optical device near the jugular vein using 400–1000 nm light and a photodetector to produce a recordable waveform output, combined with a pressure sensor and liquid-tube reference patch to determine vertical height and calculate central venous pressure. Multiple inventive features are integrated into the device architecture, with dependent claims adding structural and signal-output details.
Jugular-proximal optical sensing with 400–1000 nm light and recordable output
A device comprising at least one light source adapted to emit light in the 400 nm to 1000 nm wavelength range; and at least one photodetector adapted to receive light emitted by the light source and translate said light into a recordable output wherein said light is reflected from or transmitted through tissue of the patient.
Probe-based delivery and receipt of reflected or transmitted tissue light
At least one probe which facilitates delivery of light from the light source to an external tissue site on the patient in the proximity of the jugular vein and receipt of light reflected from or transmitted through said patient site by the photodetector.
Pressure sensor with liquid-tube reference patch to determine vertical height
A pressure sensor mounted on the probe and connected to a reference patch that is compatible for placement on the skin via a tube configured to contain a liquid, wherein the pressure sensor provides a pressure reading useful to determine vertical height from the reference patch to the probe.
Signal processing for central venous pressure from optical output and pressure reading
Signal processing means adapted to receive the photodetector output and the pressure reading from the pressure sensor and to calculate a central venous pressure therefrom.
Embedded light source and photodetector in the probe
The device wherein the light source and the photodetector are embedded within the probe.
Multiple photodetectors
The device including a plurality of photodetectors.
Paired multiple light sources and corresponding photodetectors
A device includes a plurality of light sources where each light source’s emitted light is received by a corresponding photodetector.
Multiple probes each including light delivery and detection components
A device with a plurality of probes, where each probe includes at least one light source and at least one photodetector.
Recordable output limited to current or voltage
The device configured so that its recordable output is either current or voltage.
Overall claim coverage centers on an optical device near the jugular vein using 400–1000 nm light and a photodetector to produce a recordable waveform output, combined with a pressure sensor and liquid-tube reference patch to determine vertical height and enable calculation of central venous pressure. Dependent claims add embedded probe integration, multi-detector and multi-source architectures, multiple probes, and constraining the recordable output to current or voltage.
Stated Advantages
Improved agreement after attenuation correction.
Documented Applications
Monitoring venous blood oxygenation and deriving central venous pulse/pressure using optical signals obtained near the jugular vein.
Determining central venous pressure (CVP) using optical waveform information together with pressure-based height information from a reference patch.
Use of attenuation correction for venous oxygenation measurements using a dual-wavelength separation difference and a correction factor C.
Simulated CVP testing and comparison of venous oxygenation to invasive values, with reported correlation improvements after attenuation correction.
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