Signal amplitude correction using spatial vector mapping

Abstract

Methods and computer-readable media with instructions for scaling physiological signals measured from different locations to predict a physiological event, modify a therapy, and/or send an alert. In embodiments, the physiological signals comprise heart sound data measured by different devices such as implantable medical devices and/or mobile phones with acceleration sensors.

We claim: 
     
         1 . A method comprising:
 receiving a first physiological signal produced by a body part of a subject, the first physiological signal measured at a first location;   receiving a second physiological signal produced by the body pa the second' physiological signal measured at a second location;   determining a first value of a signal characteristic, the first value of the signal characteristic corresponding to the first physiological signal;   determining a second value of the signal characteristic, the second value of the signal characteristic corresponding to the second physiological signal, wherein the signal characteristic comprises an amplitude, a phase, or a frequency;   scaling the first physiological signal based on the first location to create a first scaled value;   scaling the second physiological signal based on the second location to create a second scaled value;   based on the first scaled value and the second scaled value. performing at least one of the following:
 predicting a physiological event, 
 modifying a therapy, or 
 sending an alert. 
   
     
     
         2 . The method of  claim 1 , wherein the first physiological signal and the second physiological signal represent heart sounds. 
     
     
         3 . The method of  claim 2 , wherein the heart sounds are measured by an acceleration sensor. 
     
     
         4 . The method of  claim 1 , wherein the scaling the first physiological signal and the scaling the second physiological signal is based on a scaling map. 
     
     
         5 . The method of  claim 4 , wherein the scaling map is selected from a set of scaling maps each associated with a different patient state. 
     
     
         6 . The method of  claim 4 , wherein the scaling map comprises a plurality of scaling vectors, each of the plurality of scaling vectors corresponding to one of a plurality of locations, each scaling vector comprising at least one signal characteristic correction value used to scale the first physiological signal and the second physiological signal. 
     
     
         7 . The method of  claim 1 , wherein the first physiological signal is measured by a sensor implanted in the subject. 
     
     
         8 . The method of  claim 7 , wherein the second physiological signal is measured by a second sensor positioned externally of the subject. 
     
     
         9 . The method of  claim 1 , wherein the first physiological signal measured by a sensor positioned externally of the subject. 
     
     
         10 . The method of  claim 9 , wherein the second physiological signal s measured by a second sensor implanted in the subject. 
     
     
         11 . One or more computer-readable media having computer-executable instructions embodied thereon that, when executed by at least one processing device, are configured to cause the at least one processing device to perform a method of facilitating physiological monitoring, the method comprising:
 receiving a first physiological signal produced by a body part of a subject, the fist physiological signal measured at a first location;   receiving a second physiological signal produced by the body part, the second physiological signal measured at a second location;   determining a first value of a signal characteristic, the first value of the signal characteristic corresponding to the first physiological signal;   determining a second value of the signal characteristic, the second value of the signal characteristic corresponding to the second physiological signal, wherein the signal characteristic comprises an amplitude, a phase, or a frequency;   scaling the first physiological signal based on the first location to create a first scaled value;   scaling the second physiological signal based o the second location to create a second scaled value:   based on the first scaled value and the second scaled value, performing at least one of the following:
 predicting a physiological event, 
 sending instructions to modify a therapy, or 
 sending an alert. 
   
     
     
         12 . The media of  claim 11  wherein the first physiological signal and the second physiological signal are represented by acceleration signals. 
     
     
         13 . The media of  claim 11 , wherein the first physiological signal and the second physiological signal represent heart sounds. 
     
     
         14 . The media of  claim 11 , wherein the first physiological signal and the second physiological signal are filtered to, at least partially, filter out non-heart sound acceleration frequencies. 
     
     
         15 . The media of  claim 11 , wherein the scaling the first physiological signal and the scaling the second physiological, signal is based on a scaling map. 
     
     
         16 . The media of  claim 15 , wherein the scaling map comprises a plurality of scaling vectors, each of the plurality of scaling vectors corresponding to one of a plurality of locations, each scaling vector comprising at least one signal characteristic correction value used to scale the first physiological signal and the second physiological signal 
     
     
         17 . The media of  claim 11 , wherein the scaling the first physiological signal and the scaling the second physiological signal is based on an orientation of the subject. 
     
     
         18 . The media of  claim 11 , wherein the first location and the second location are both within a chest region and/or a back region. 
     
     
         19 . The media of  claim 11 , wherein the first physiological signal and the second physiological signal are measured by separate devices. 
     
     
         20 . The media of  claim 19 , wherein the first physiological signal is measured by an implantable medical device with a first acceleration sensor, wherein the second physiological signal is measured by a mobile phone with a second acceleration sensor.