OPTICAL SENSORS FOR USE IN VITAL SIGN MONITORING

• US 20120179011A1
• Filed: 11/09/2011
• Published: 07/12/2012
• Est. Priority Date: 06/12/2007
• Status: Active Grant

• Current Assignee: Sotera Wireless Incorporated
• Original Assignee: Sotera Wireless Incorporated
• Inventors: Moon, Jim, Banet, Matt, Dhillon, Marshal, McCombie, Devin
• Granted Patent: US 11,607,152 B2
• Time in Patent Office: Days
• US Class Current: 600/324
• CPC Class Codes: A61B 2560/0412 Low-profile patch shaped housings
• CPC Class Codes: A61B 2560/0462 Apparatus with built-in sensors
• CPC Class Codes: A61B 2560/0468 Built-in electrodes
• CPC Class Codes: A61B 2562/0219 Inertial sensors, e.g. accelerometers, gyroscopes, tilt switches
• CPC Class Codes: A61B 5/0002 Remote monitoring of patients using telemetry, e.g. transmission of vital signals via a communication network A61B5/07 takes precedence; transmission systems for measured values G08C; transmission H04B; transmission of digital information H04L; wireless communication networks H04W
• CPC Class Codes: A61B 5/02055 Simultaneously evaluating both cardiovascular condition and temperature
• CPC Class Codes: A61B 5/02225 using the oscillometric method
• CPC Class Codes: A61B 5/0245 by using sensing means generating electric signals, i.e. ECG signals
• CPC Class Codes: A61B 5/0816 Measuring devices for examining respiratory frequency measuring frequency of electric signals G01R23/00
• CPC Class Codes: A61B 5/1116 Determining posture transitions
• CPC Class Codes: A61B 5/1117 Fall detection
• CPC Class Codes: A61B 5/1118 Determining activity level
• CPC Class Codes: A61B 5/14551 for measuring blood gases
• CPC Class Codes: A61B 5/25 Bioelectric electrodes therefor
• CPC Class Codes: A61B 5/6826 Finger
• CPC Class Codes: A61B 5/6838 Clamps or clips
• CPC Class Codes: A61B 5/7207 of noise induced by motion artifacts
• CPC Class Codes: A61B 5/7225 Details of analog processing, e.g. isolation amplifier, gain or sensitivity adjustment, filtering, baseline or drift compensation A61B5/30, A61B5/316 take precedence; transformers for specific applications H01F38/00; amplifiers H03F
• CPC Class Codes: A61B 5/7239 using differentiation including higher order derivatives
• CPC Class Codes: A61B 5/746 Alarms related to a physiological condition, e.g. details of setting alarm thresholds or avoiding false alarms alarms per se G08B

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.

Claims

1. An optical sensor configured to be worn on a patient'"'"'s finger and determine an optical signal indicative of a photoplethysmograph waveform, the sensor comprising:

a housing configured to wrap around the base of the patient'"'"'s finger and position over the interior base of the finger proximate to an artery which permits monitoring of the absorption characteristics of oxygenated and deoxygenated hemoglobin and which carries a pulse pressure wave which permits determination of blood pressure from the pulse transit time (i) a light source that emits optical radiation, and (ii) a photodetector configured to detect the optical radiation after reflection by the artery and to generate the optical signal.

2. An optical sensor according to claim 1, the housing configured to wrap around the base of the patient'"'"'s thumb and position over the interior base of the thumb proximate to the princeps pollicis artery (i) the light source that emits optical radiation, and (ii) the photodetector configured to detect the optical radiation after reflection by the princeps pollicis artery and to generate the optical signal.

3. An optical sensor according to claim 1, further comprising circuitry configured to receive the optical signal and convert the optical signal into a photoplethysmograph waveform.

4. An optical sensor according to claim 3, wherein the photoplethysmograph waveform is an analog waveform.

5. An optical sensor according to claim 1, wherein the band is configured to be worn by the patient while leaving the tip of the patient'"'"'s finger uncovered.

6. An optical sensor according to claim 1, comprising at least two light sources.

7. An optical sensor according to claim 6, wherein at least one light source operates in the 400-700 nm range, and at least one other light source operates in the 700-1000 nm range.

8. A method of obtaining an optical signal indicative of a photoplethysmograph waveform, comprising:

positioning a housing around the base of a patient'"'"'s thumb, wherein the housing comprises (i) a light source that emits optical radiation, and (ii) a photodetector configured to detect the optical radiation, wherein the light source and photodetector are each positioned 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 the after reflection by the princeps pollicis artery with the photodetector and generating an optical signal therewith.

9. A method according to claim 8, further comprising converting the optical signal into a photoplethysmograph waveform.

10. A method according to claim 9, further comprising determining one or more of a blood oxygen saturation level, a pulse rate, a pulse transit time, and a blood pressure for the patient using the photoplethysmograph waveform.

11. A method of obtaining an optical signal indicative of a photoplethysmograph waveform, comprising:

positioning a housing around the base of a patient'"'"'s finger, thereby positioning over the interior base of the finger proximate to an artery which permits monitoring of the absorption characteristics of oxygenated and deoxygenated hemoglobin and which carries a pulse pressure wave which permits determination of blood pressure from the pulse transit time (i) a light source that emits optical radiation, and (ii) a photodetector configured to detect the optical radiation after reflection by the artery and to generate the optical signal;

energizing the light source to illuminate the finger with optical radiation; and

detecting optical radiation the after reflection by the artery with the photodetector and generating an optical signal therewith.

12. A method according to claim 11, further comprising converting the optical signal into a photoplethysmograph waveform.

13. A method according to claim 12, further comprising determining one or more of a blood oxygen saturation level, a pulse rate, a pulse transit time, and a blood pressure for the patient using the photoplethysmograph waveform.