Systems and methods for normalizing a plethysmograph signal for improved feature analysis

Abstract

The present disclosure relates to systems and methods for analyzing and normalizing signals, such as PPG signals, for use in patent monitoring. The PPG signal may be detected using a continuous non-invasive blood pressure monitoring system and the normalized signals may be used to determine whether a recalibration of the system should be performed.

What is claimed is: 
     
         1 . A method for normalizing a light intensity signal using a physiological monitoring system, comprising:
 receiving, using a processor, a light intensity signal from a subject at a first time;   obtaining, using the processor, information indicating a change in a setting of the monitoring system;   receiving, using a processor, a light intensity signal from a subject at a second time, wherein the first time occurs before the change in the setting of the monitoring system and the second time occurs after the change in the setting of the monitoring system;   normalizing, using the processor, the light intensity signal at the second time in response to the change in the setting of the monitoring system;   comparing, using the processor, the light intensity signal at the first time and the normalized light intensity signal at the second time; and   triggering, using the processor, an action, based at least in part on whether the light intensity signal at the first time and the normalized light intensity signal at the second time correspond.   
     
     
         2 . The method of  claim 1 , wherein normalizing the light intensity signal at the second time comprises performing a calculation based at least in part on a change in amplitude, area, pulse period, baseline, or any combination thereof. 
     
     
         3 . The method of  claim 1 , wherein obtaining information indicating a change in a setting of the monitoring system comprises receiving a user input. 
     
     
         4 . The method of  claim 1 , wherein the action comprises calculating a physiological parameter of the subject. 
     
     
         5 . The method of  claim 1 , wherein the action comprises generating an alarm signal. 
     
     
         6 . The method of  claim 1 , wherein the action comprises generating a recalibration request. 
     
     
         7 . The method of  claim 1 , wherein the comparing comprises comparing a metric of the light intensity signal at the first time and a metric of the normalized light intensity signal at the second time 
     
     
         8 . The method of  claim 7 , wherein the metric comprises: peak amplitude, area, period, baseline, or any combination thereof. 
     
     
         9 . A system for normalizing a light intensity signal in a physiological monitoring system, comprising a processor configured for:
 receiving a light intensity signal from a subject at a first time;   obtaining information indicating a change in a setting of the monitoring system;   receiving a light intensity signal from a subject at a second time, wherein the first time occurs before the change in the setting of the monitoring system and the second time occurs after the change in the setting of the monitoring system;   normalizing the light intensity signal at the second time in response to the change in the setting of the monitoring system;   comparing the light intensity signal at the first time and the normalized light intensity signal at the second time; and   triggering an action, based at least in part on whether the light intensity signal at the first time and the normalized light intensity signal at the second time correspond.   
     
     
         10 . The system of  claim 9 , wherein normalizing the light intensity signal at the second time comprises performing a calculation based at least in part on a change in amplitude, area, pulse period, baseline, or any combination thereof. 
     
     
         11 . The system of  claim 9 , wherein obtaining information indicating a change in a setting of the monitoring system comprises receiving a user input. 
     
     
         12 . The system of  claim 9 , wherein the action comprises calculating a physiological parameter of the subject. 
     
     
         13 . The system of  claim 9 , wherein the action comprises generating an alarm signal. 
     
     
         14 . The system of  claim 9 , wherein the action comprises generating a recalibration request. 
     
     
         15 . The system of  claim 9 , wherein the comparing comprises comparing a metric of the light intensity signal at the first time and a metric of the normalized light intensity signal at the second time 
     
     
         16 . The system of  claim 15 , wherein the metric comprises: peak amplitude, area, period, baseline, or any combination thereof.