Optical sensors for use in vital sign monitoring
Inventors
Moon, Jim • McCOMBIE, Devin • Banet, Matt • Dhillon, Marshal
Assignees
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Publication Number
US-11607152-B2
Publication Date
2023-03-21
Expiration Date
Abstract
The invention provides a body-worn system that continuously measures pulse oximetry and blood pressure, along with motion, posture, and activity level, from an ambulatory patient. The system features an oximetry probe that comfortably clips to the base of the patient's thumb, thereby freeing up their fingers for conventional activities in a hospital, such as reading and eating. The probe secures to the thumb and measures time-dependent signals corresponding to LEDs operating near 660 and 905 nm. Analog versions of these signals pass through a low-profile cable to a wrist-worn transceiver that encloses a processing unit. Also within the wrist-worn transceiver is an accelerometer, a wireless system that sends information through a network to a remote receiver, e.g. a computer located in a central nursing station.
Core Innovation
The invention provides a method of obtaining an optical signal indicative of a photoplethysmograph waveform by positioning an approximately semicircular flexible housing around the base of a patient's thumb. The housing includes a first light source that emits optical radiation with a first substantially planar surface, and a photodetector positioned on a substrate with a second substantially planar surface, with the first and second substantially planar surfaces supported by the flexible housing and separated by an included angle between 35 and 55 degrees.
The first light source and the photodetector are each positioned over the interior base of the thumb proximate to the princeps pollicis artery. The method energizes the light source to illuminate the thumb with optical radiation, and detects optical radiation after reflection by the princeps pollicis artery with the photodetector to generate an optical signal.
The housing includes a plurality of living hinges radially spaced apart along a circumference of the approximately semicircular housing. By using the thumb base arrangement proximate to the princeps pollicis artery and the defined flexible housing geometry with living hinges, the method enables an optical signal indicative of a photoplethysmograph waveform.
Claims Coverage
The provided material identifies one independent claim covering a thumb-based optical sensing method with a specified flexible housing geometry and an optical signal indicative of a photoplethysmograph waveform. Dependent coverage further adds conversion to a photoplethysmograph waveform and determination of physiological measurements.
Thumb base flexible housing with living hinges at defined planar included angle
Positioning an approximately semicircular flexible housing around the base of a patient's thumb, where the housing comprises a first light source with a first substantially planar surface, a photodetector positioned on a substrate having a second substantially planar surface, and a plurality of living hinges such that the first and second substantially planar surfaces are separated by an included angle between 35 and 55 degrees.
Placement over princeps pollicis artery and reflection-based detection
Positioning the first light source and the photodetector over the interior base of the thumb proximate to the princeps pollicis artery, energizing the light source to illuminate the thumb with optical radiation, and detecting optical radiation after reflection by the princeps pollicis artery with the photodetector to generate an optical signal indicative of a photoplethysmograph waveform.
Conversion into photoplethysmograph waveform for patient measurements
Converting the optical signal into a photoplethysmograph waveform and determining one or more of a blood oxygen saturation level, a pulse rate, a pulse transit time, and blood pressure for the patient using the photoplethysmograph waveform.
Optional second light source proximate to the first light source
Arranging that the flexible housing further comprises a second light source proximate to the first light source within the housing.
Overall, claim coverage centers on a thumb base, flexible, living-hinge housing that spaces first and second substantially planar surfaces by an included angle between 35 and 55 degrees, places a light source and photodetector over the interior thumb base proximate to the princeps pollicis artery, and generates an optical signal indicative of a photoplethysmograph waveform from reflected optical radiation. Dependent coverage adds conversion to a photoplethysmograph waveform for determining blood oxygen saturation level, pulse rate, pulse transit time, and blood pressure, and also allows inclusion of a second light source proximate to the first.
Stated Advantages
Documented Applications
Not explicitly described in patent.
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