Apparatus and methods for monitoring a subject

Abstract

Apparatus and methods are described for monitoring a subject. A sensor is configured to monitor the subject without contacting the subject or clothes the subject is wearing, and without viewing the subject or clothes the subject is wearing, and to generate a sensor signal in response to the monitoring. A computer processor is configured to: (a) receive the sensor signal, (b) extract from the sensor signal a plurality of heartbeats of the subject, and, for each of the extracted heartbeats, an indication of a quality of the extracted heartbeat, (c) select a subset of heartbeats, based upon the qualities of the extracted heartbeats, (d) for only the subset of heartbeats, determine interbeat intervals between adjacent heartbeats, (e) in response thereto, determine a physiological state of the subject, and (f) generate an output in response thereto. Other applications are also described.

1 - 40 . (canceled) 
     
     
         41 . Apparatus for monitoring a subject, the apparatus comprising:
 a sensor, configured to monitor the subject without contacting the subject or clothes the subject is wearing, and without viewing the subject or clothes the subject is wearing, and to generate a sensor signal in response to the monitoring; and   a computer processor, configured to:
 receive the sensor signal, 
 extract from the sensor signal a plurality of heartbeats of the subject, and, for each of the extracted heartbeats, an indication of a quality of the extracted heartbeat, 
 select a subset of heartbeats, based upon the qualities of the extracted heartbeats, 
 for only the subset of heartbeats, determine interbeat intervals between adjacent heartbeats, 
 in response thereto, determine a physiological state of the subject, and 
 generate an output in response thereto. 
   
     
     
         42 . (canceled) 
     
     
         43 . The apparatus according to  claim 41 , wherein the computer processor is configured to extract the indication of the quality of the extracted heartbeat by determining a signal-to-noise ratio of the sensor signal. 
     
     
         44 . The apparatus according to  claim 43 , wherein the computer processor is configured to select the subset of heartbeats by: (a) comparing the signal-to-noise ratio of the sensor signal to a threshold, and (b) selecting pairs of consecutive heartbeats based on the signal-to-noise ratio exceeding the threshold. 
     
     
         45 . The apparatus according to  claim 41 , wherein the computer processor is configured to select the subset of heartbeats by comparing the indication of the quality of each extracted heartbeat to a threshold, and selecting pairs of consecutive heartbeats having a quality indicator that exceeds the threshold. 
     
     
         46 . The apparatus according to  claim 41 , wherein subsequently to determining the interbeat intervals between adjacent heartbeats, the computer processor is configured to build a histogram of the interbeat intervals for the subset of heartbeats, analyze the histogram, and in response thereto, determine the physiological state of the subject. 
     
     
         47 . The apparatus according to  claim 46 , wherein, in response to analyzing the histogram, the computer processor is configured to determine whether the subject is healthy or is suffering from arrhythmia. 
     
     
         48 . The apparatus according to  claim 47 , wherein in response to determining that the subject is suffering from arrhythmia, the computer processor is further configured to determine which type of arrhythmia the subject is suffering from. 
     
     
         49 . The apparatus according to  claim 46 , wherein, in response to analyzing the histogram, the computer processor is configured to predict an arrythmia episode. 
     
     
         50 . The apparatus according to  claim 46 , wherein, in response to analyzing the histogram, the computer processor is configured to identify that an arrhythmia event may be occurring. 
     
     
         51 . The apparatus according to  claim 50 , wherein the computer processor is configured to identify that the arrhythmia event may be taking place in response to the computer processor identifying two distinct peaks in the histogram. 
     
     
         52 . The apparatus according to  claim 51 , wherein, in response to identifying two distinct peaks in the histogram, the computer processor is configured to:
 identify heartbeats belonging to respective interbeat interval groups by identifying which heartbeats had an interbeat interval corresponding to a first one of the peaks, and which heartbeats had an interbeat interval corresponding to the second one of the peaks; and   calculate the average amplitude of the sensor signal of each interbeat interval group.   
     
     
         53 . The apparatus according to  claim 52 , wherein the computer processor is configured to generate an output that is indicative of the average amplitude of each of the peaks. 
     
     
         54 . The apparatus according to  claim 52 , wherein the computer processor is configured to generate an output that is indicative of the average amplitude of the interbeat interval of each of the peaks. 
     
     
         55 . The apparatus according to  claim 52 , wherein, based upon the average amplitude of the sensor signal of each interbeat interval group, the computer processor is further configured to determine a category of arrhythmia that the subject is suffering from selected from the group consisting of: atrial fibrillation and ventricular fibrillation. 
     
     
         56 . The apparatus according to  claim 50 , wherein the computer processor is configured to identify that the arrhythmia event may be occurring in response to the computer processor identifying a peak in the histogram that has a width that exceeds a threshold width. 
     
     
         57 . The apparatus according to  claim 56 , wherein the computer processor is configured to determine the threshold width based on population averages regarding a parameter of the subject indicated by the subject. 
     
     
         58 . The apparatus according to  claim 57 , wherein the parameter of the subject is an indication of the subject's age or an indication of a level of fitness of the subject.