Optical vital sign detection method and measurement device

Abstract

A vital sign measurement device includes an optical sensing system and an output unit. The optical sensing system includes an optical source, an optical refractor, and an optical detector. The optical sensing system is placed against the anatomical location of the subject to sense movement corresponding to an arterial pulse. The optical sensing system can sense an arterial pulse from the movement, bending, or compression of at least one portion of the optical sensing system relative to other portions of the optical sensing system resulting in a change in an optical signal received by the optical detector. The output unit generates a measure of a vital sign.

What is claimed is: 
     
         1 . A vital sign measurement device comprising:
 a sensor fixation device adapted to be placed against an anatomical location of a subject, within which is an artery;   an optical sensing system comprising an optical source, an optical refractor, and an optical detector, all of which are held by the sensor fixation device and move with movement of the sensor fixation device, the optical sensing system positioned with respect to the sensor fixation device to sense movement corresponding to an arterial pulse when the sensor fixation device is placed against the anatomical location of the subject, the optical sensing system sensing an arterial pulse from the movement, bending, or compression of at least one portion of the optical sensing system relative to other portions of the optical sensing system resulting in a change in an optical signal received by the optical detector; and   an output unit that receives, from the optical sensing system, an input indicative of movement corresponding to an arterial pulse and that generates, using the input, a measure of the vital sign.   
     
     
         2 . The vital sign measurement device of  claim 1 , wherein the sensor fixation device is an inflatable cuff. 
     
     
         3 . The vital sign measurement device of  claim 1 , further comprising a pressure sensor to detect a pressure applied to the anatomical location, wherein the output unit receives, from the pressure sensor, a pressure input indicative of the pressure applied to the anatomical location, wherein the output unit generates the vital sign using the input from the optical sensing system and the pressure input. 
     
     
         4 . The vital sign measurement device of  claim 1 , wherein the anatomical location of the subject the body is an upper arm, and the sensor fixation device is configured so that the optical sensing system is positionable to sense movement due to a pulse of a brachial artery. 
     
     
         5 . The vital sign measurement device of  claim 1 , wherein the anatomical location of the subject is a wrist, and the sensor fixation device is configured so that the optical sensing system is positionable to sense movement due to a pulse of a radial artery. 
     
     
         6 . The vital sign measurement device of  claim 1 , wherein the anatomical location of the subject is an ankle, and the sensor fixation device is configured so that the optical sensing system is positionable to sense movement due to a pulse of one or more arteries in the ankle 
     
     
         7 . The vital sign measurement device of  claim 1 , wherein the optical refractor is a compressible waveguide. 
     
     
         8 . The vital sign measurement device of  claim 1 , wherein the optical refractor is a flexible waveguide. 
     
     
         9 . The vital sign measurement device of  claim 1 , wherein the optical refractor is a diffuser. 
     
     
         10 . The vital sign measurement device of  claim 1 , wherein the optical source and the optical refractor are configured to produce a speckle pattern output. 
     
     
         11 . The vital sign measurement device of  claim 10 , wherein the optical detector is positioned to detect a portion of the speckle pattern output and generate therefrom a signal indicative of optical energy received within the detected portion of the speckle pattern output. 
     
     
         12 . The vital sign measurement device of  claim 11 , wherein the optical sensor further comprises a spatial optical occluder component that prevents the optical detector from receiving a portion of the speckle pattern output. 
     
     
         13 . The vital sign measurement device of  claim 11 , wherein the optical detector comprises an optical energy receiving portion having a smaller surface area than the speckle pattern output. 
     
     
         14 . The vital sign measurement device of  claim 13 , wherein the surface area of the optical energy receiving portion is less than  100  times an average speckle size. 
     
     
         15 . The vital sign measurement device of  claim 1 , wherein the optical source is a coherent light source. 
     
     
         16 . The vital sign measurement device of  claim 1 , wherein the vital sign is at least one of a heart rate, an arterial pulse waveform, a systolic blood pressure, a diastolic blood pressure, a mean arterial blood pressure, a pulse pressure, and an arterial compliance. 
     
     
         17 . The vital sign measurement device of  claim 1 , wherein the output unit generates a measure of the vital sign using a signal indicative of the optical signal received by the optical detector. 
     
     
         18 . The vital sign measurement device of  claim 1 , further comprising a display to depict a vital sign measurement generated by the output unit. 
     
     
         19 . The vital sign measurement device of  claim 1 , further comprising an alarm system to produce a human detectable signal when a vital sign measurement generated by the output unit meets a predetermined criteria. 
     
     
         20 . The vital sign measurement device of  claim 1 , further comprising a spring attached to at least a portion of the optical sensing system to counter a force from the arterial pulse and to return the optical sensing system to an initial state after the arterial pulse. 
     
     
         21 . The vital sign measurement device of  claim 1 , further comprising a pressure imparting device adapted to be placed against a second anatomical location of a subject proximal to the anatomical location of the sensor fixation device to allow for arterial pulse detection by the optical sensing system at a position distal to and separated from the pressure imparting device. 
     
     
         22 . The vital sign measurement device of  claim 1 , wherein the optical sensing system and the output unit are adapted to sense a pulse amplitude of the arterial pulse from the movement, bending, or compression of at least one portion of the optical sensing system relative to other portions of the optical sensing system resulting in a change in the optical signal received by the optical detector. 
     
     
         23 . The vital sign measurement device of  claim 22 , wherein the optical sensing system is configured to detect optical signals representative of a series of arterial pulses and the output unit is adapted to determine a pulse waveform for each of the series of arterial pulses. 
     
     
         24 . A method of measuring a vital sign of a subject, the method comprising:
 placing a sensor fixation device against an anatomical location of a subject, within which is an artery, the sensor fixation device holding an optical sensing system comprising an optical source, an optical refractor and an optical detector, all of which are held by the sensor fixation device and move with movement of the sensor fixation device;   sensing movement corresponding to an arterial pulse by operating the optical sensing system, the arterial pulse resulting in the movement, bending, or compression of at least one portion of the optical sensing system relative to other portions of the optical sensing system resulting in a change in a optical signal received by the optical detector; and   generating a measure of the vital sign using an input indicative of the changes in the amount of optical energy received by the optical detector.   
     
     
         25 . The method of  claim 24 , the method further comprising:
 applying a pressure to the anatomical location of the subject with the sensor fixation device.   
     
     
         26 . The method of  claim 25 , the method further comprising:
 reducing the pressure applied to the anatomical location with the sensor fixation device over the period of time;   determining a series of pulse characteristics for arterial pulses during the period of time from changes in the optical signal received by the optical detector over the period of time, wherein the generated measure of the vital sign is based on the series of pulse characteristics during the period of time.   
     
     
         27 . The method of  claim 25 , further comprising
 obtain a measured blood pressure measurement;   obtaining an initial pulse characteristic, at an initial time, and a subsequent pulse characteristic, at a subsequent time, using an input indicative of the sensed movement from the optical sensing system, wherein the measured blood pressure measurement was obtained at a measurement time closer to the initial time than to the subsequent time, wherein the generated measurement of the vital sign is based on the measured blood pressure measurement, the initial pulse characteristic, and the subsequent pulse characteristic.   
     
     
         28 . The method of  claim 24 , wherein the optical source and the optical refractor are configured to produce a speckle pattern output that changes in response to relative movement of optical source and the optical refractor. 
     
     
         29 . The method of  claim 24 , wherein the vital sign is at least one of a heart rate, an arterial pulse waveform, a systolic blood pressure, a diastolic blood pressure, a mean arterial blood pressure, a pulse pressure, and an arterial compliance. 
     
     
         30 . The method of  claim 24 , wherein generating the measure of the vital sign using the input indicative of the sensed movement comprises determining a pulse amplitude from changes in the amount of optical energy received by the optical detector.