# US 9,775,529 B2 · Body-worn pulse oximeter > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,775,529 B2 - Document ID: US9775529B2 - Status: Granted - Kind: B2 - Application number: 12/559,386 - Filed: 2009-09-14 - Published: 2010-12-23 - Granted: 2017-10-03 - Earliest claimed: 2009-06-17 - Assignees: Sotera Wireless, Inc. - Applicants: Jim Moon; Devin McCombie; Marshal Dhillon; Matt Banet - Inventors: Jim Moon; Devin McCombie; Marshal Dhillon; Matt Banet - Web page: https://patentgrep.com/patent/US9775529B2 ## CPC - A61B 5/0245: by using sensing means generating electric signals, {i.e. ECG signals} - A61B 5/02125: {of pulse wave propagation time} - A61B 5/022: by applying pressure to close blood vessels, e.g. against the skin; Ophthalmodynamometers - A61B 5/1118: {Determining activity level} - A61B 5/14551: {for measuring blood gases} - A61B 5/14552: {Details of sensors specially adapted therefor} - A61B 5/349: Detecting specific parameters of the electrocardiograph cycle - A61B 5/681: {Wristwatch-type devices} - A61B 5/6826: {Finger} - A61B 5/6838: {Clamps or clips} - A61B 5/746: {Alarms related to a physiological condition, e.g. details of setting alarm thresholds or avoiding false alarms} - A61B 5/021: Measuring pressure in heart or blood vessels - A61B 5/02225: {using the oscillometric method} - A61B 5/1116: {Determining posture transitions} - A61B 5/6824: {Arm or wrist} - A61B 5/721: {using a separate sensor to detect motion or using motion information derived from signals other than the physiological signal to be measured} - A61B 5/7239: {using differentiation including higher order derivatives} - A61B: DIAGNOSIS; SURGERY; IDENTIFICATION (usefulness limited to only animals A61D) ## 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 ### Claim 1 A method for determining an oxygen saturation value from a patient, comprising the following steps: (a) positioning a first radiation source, a second radiation source, and a radiation detector on the base of the thumb such that the first radiation source and second radiation source are positioned proximally to one another and the radiation detector is positioned at an included angle of between 35° and 55°, wherein the included angle is the angle formed between a first plane drawn parallel to a planar surface comprising the emitting surface of the first and second radiation sources and a second plane drawn parallel to a planar surface of a circuit board comprising the receiving surface of the radiation detector, and such that a first radiation emitted by the first radiation source and a second radiation emitted by the second radiation source pass through the thumb tissue and are received by the princeps pollicis artery before reaching the radiation detector; (b) measuring a first time-dependent signal by detecting the first radiation emitted by the first radiation source after the first radiation passes through the thumb tissue; (c) measuring a second time-dependent signal by detecting the second radiation emitted by the second radiation source after the second radiation passes through a portion of the patient; (d) measuring a time-dependent motion signal with at least one motion sensor; (e) measuring a time-dependent electrical signal with an electrical sensor comprising at least two electrodes; (f) processing the time-dependent electrical signal to determine at least one reference point; (g) processing the time-dependent motion signal to determine if a motion-related event that affects at least one of the first and second time-dependent signals has occurred that would render the first and second time-dependent signals unreliable for calculation of SpO2; (h) if the motion event that would render the first and second time-dependent signals unreliable for calculation of SpO2 has not occurred, processing both the first and second time-dependent signals from the reference point to determine processed forms of the first and second time-dependent signals; and (i) determining the oxygen saturation value from the processed forms of the first and second time-dependent signals. ### Claim 2 (depends on 1) The method of claim 1, wherein step (g) further comprises processing the time-dependent motion signal to determine a motion-related event selected from the patient's posture, activity level, and degree of motion. ### Claim 3 (depends on 2) The method of claim 2, wherein the motion-related event is posture, and step (g) further comprises determining a parameter corresponding to orientation of the patient's torso. ### Claim 4 (depends on 3) The method of claim 3, wherein the parameter corresponding to orientation of the patient's torso is a vector. ### Claim 5 (depends on 4) The method of claim 4, wherein step (g) further comprises processing signals corresponding to three axes of a motion sensor to determine the vector. ### Claim 6 (depends on 5) The method of claim 5, wherein the motion sensor is an accelerometer. ### Claim 7 (depends on 5) The method of claim 5, wherein step (g) further comprises comparing the vector to a pre-determined coordinate system to determine an angle. ### Claim 8 (depends on 7) The method of claim 7, wherein step (g) further comprises comparing the angle to a set of pre-determined values, each corresponding to a different posture, to determine the patient's posture. ### Claim 9 (depends on 2) The method of claim 2, wherein the motion-related event is activity level, and step (g) further comprises processing time-dependent variations in the motion signal to determine the activity level. ### Claim 10 (depends on 9) The method of claim 9, wherein the activity level corresponds to one of moving, walking, falling, convulsing. ### Claim 11 (depends on 9) The method of claim 9, wherein step (g) further comprises performing a mathematical transform of the time-dependent variations to determine a frequency-domain spectrum. ### Claim 12 (depends on 11) The method of claim 11, wherein step (g) further comprises comparing portions of the frequency-domain spectrum to pre-determined frequency parameters to determine the activity level. ### Claim 13 (depends on 9) The method of claim 9, wherein step (g) further comprises comparing magnitudes of the time-dependent variations in the motion signal to pre-determined magnitude parameters to determine the activity level. ### Claim 14 (depends on 9) The method of claim 9, wherein step (g) further comprises taking a mathematical derivative of the time-dependent motion signal to determine the time-dependent variations. ### Claim 15 (depends on 2) The method of claim 2, wherein the motion-related event is a degree of motion, and step (g) further comprises determining an amplitude of a portion of the time-dependent motion signal to determine the degree of motion. ### Claim 16 (depends on 15) The method of claim 15, wherein step (g) further comprises performing a mathematical transform of the time-dependent variations to determine a frequency-domain spectrum. ### Claim 17 (depends on 16) The method of claim 16, wherein step (g) further comprises determining a power of the frequency-domain spectrum to determine the degree of motion. ### Claim 18 (depends on 1) The method of claim 1, wherein step (e) further comprises measuring an ECG signal. ### Claim 19 (depends on 18) The method of claim 18, wherein step (e) further comprises detecting a QRS complex in the ECG signal to determine the reference point. ### Claim 20 (depends on 19) The method of claim 19, wherein step (h) further comprises processing both the first and second signals during a pre-determined time period that follows the QRS complex. ### Claim 21 (depends on 20) The method of claim 20, wherein the predetermined time period is less than 500 ms.