Low Power Device With Contingent Scheduling

Abstract

Medical device systems and methods for operating medical device systems conserve energy by efficiently managing computational demands of the systems. A first analysis, having relatively lower computational processing demand than at least a second analysis, processes signals from a subject to determine a first estimate of a propensity for the subject to have a neurological event. If the first estimate meets a set of specified criteria, a second analysis is performed to determine a second estimate of the propensity for the subject to have a neurological event.

1 . A method of operating a medical device system, the method comprising:
 receiving at least one signal from a physiological sensor;   processing the at least one signal by performing a first analysis to estimate a first propensity for a subject to have a neurological event; and   performing a second analysis to estimate a second propensity for the subject to have a neurological event when the first estimate meets one or more specified criteria.   
     
     
         2 . The method of  claim 1  wherein performing the first analysis requires less computational power than performing the second analysis. 
     
     
         3 . The method of  claim 1  further comprising modifying the one or more specified criteria based on a charge measurement for a battery associated with the medical device system. 
     
     
         4 . The method of  claim 1  wherein receiving at least one signal comprises measuring one or more electrical signals generated by neural activity. 
     
     
         5 . The method of  claim 4  wherein processing the at least one signal comprises analyzing said at least one signal by a first set of feature extractors. 
     
     
         6 . The method of  claim 5  wherein the first set of feature extractors comprises one or more feature extractors selected from the group consisting of frequency based feature extractors, phase coherence feature extractors, and band power feature extractors. 
     
     
         7 . The method of  claim 5  wherein at least one of the feature extractors in the first set of feature extractors is selected based on information about the subject. 
     
     
         8 . The method of  claim 5  wherein the second analysis comprises logic to analyze the at least one signal by a second set of feature extractors. 
     
     
         9 . The method of  claim 8  wherein said second set of feature extractors is characterized by relatively high specificity and relatively high computational complexity in comparison to the first set of feature extractors. 
     
     
         10 . The method of  claim 4  wherein the estimate of a first propensity for the subject to have a neurological event is an estimate of a probability for the subject to have a neurological event within a specified time frame. 
     
     
         11 . The method of  claim 4  wherein the neurological event is a seizure. 
     
     
         12 . The method of  claim 1  further comprising communicating to the subject information indicative of the second estimate when the first estimate meets the one or more specified criteria. 
     
     
         13 . The method of  claim 1  wherein performing the first analysis and performing the second analysis is performed by a processing system that is external to the subject. 
     
     
         14 . The method of  claim 1  wherein performing the first analysis is performed by a first processing system and performing the second analysis is performed by a second processing system. 
     
     
         16 . The method of  claim 1  further comprising:
 pre-processing the at least one signal using a first processing system to derive data representative of the one or more signals;   communicating the derived data representative of the at least one signal to a second processing system, wherein the steps of processing the at least one signal by performing a first analysis and performing a second analysis are performed by the second processing system.   
     
     
         17 . The method of  claim 16  wherein the first processing system is implanted in the subject and the second processing system is external to the subject. 
     
     
         18 . A system for estimating a propensity for a subject to have a neurological event comprising:
 one or more sensors for measuring at least one signal from the subject;   first logic arranged to analyze the at least one signal from the subject and estimate a first propensity for the subject to have a neurological event;   a processor configured to perform the first logic;   second logic configured to be performed when the first estimate meets one or more specified criteria and arranged to estimate a second propensity for the subject to have a neurological event.   
     
     
         19 . The system of  claim 18  wherein the first logic is embodied in executable instructions stored on computer accessible media and the second logic is embodied in executable instructions stored on computer accessible media. 
     
     
         20 . The system of  claim 18  wherein the first logic is embodied in a programmable logic device and the second logic is embodied in a programmable logic device. 
     
     
         21 . The system of  claim 18  wherein the first logic is embodied in a circuit and the second logic is embodied in a circuit. 
     
     
         22 . The system of  claim 18  wherein estimating the first propensity requires less computational power than estimating the second propensity. 
     
     
         23 . The system of  claim 18  wherein the estimate of the first propensity is a measure of the likelihood for the subject to have a neurological event within a specified time period after the signals are detected. 
     
     
         24 . The system of  claim 23  wherein the specified criteria comprise the condition of the estimate of the first propensity indicating that a likelihood for the subject to have a neurological event exceeds a specified threshold. 
     
     
         25 . The system of  claim 18  wherein the one or more sensors comprise one or more sensors for measuring brain activity signals of the subject. 
     
     
         26 . The system of  claim 25  wherein the neurological event is an epileptic seizure. 
     
     
         27 . The system of  claim 18  wherein the processor is external to the subject and the processor is configured to perform the second logic. 
     
     
         28 . A device comprising:
 means for measuring at least one signal from a subject;   means for analyzing the at least one signal from a subject to estimate a first propensity for the subject to have a neurological event;   means for determining whether the estimate of the first propensity meets one or more specified criteria;   means for estimating a second propensity for the subject to have a neurological event when the estimate of the first propensity meets the one or more specified criteria.   
     
     
         29 . A system for estimating a propensity for a subject to have an epileptic seizure comprising:
 at least one sensor for measuring at least one neurological signal from the subject;   first logic arranged to extract at least one feature from the at least one neurological signal and to classify the extracted at least one feature to estimate a first propensity of the subject to have an epileptic seizure;   a processor configured to perform the first logic;   second logic arranged to estimate a second propensity of the subject to have an epileptic seizure when the estimate of the first propensity meets at least one specified criteria; and   a processor configured to perform the second logic.   
     
     
         30 . The system of  claim 29  wherein the first logic is embodied in executable instructions stored on computer accessible media and the second logic is embodied in executable instructions stored on computer accessible media. 
     
     
         31 . The system of  claim 29  wherein the first logic is embodied in a programmable logic device and the second logic is embodied in a programmable logic device. 
     
     
         32 . The system of  claim 29  wherein the first logic is embodied in a circuit and the second logic is embodied in a circuit. 
     
     
         33 . The system of  claim 29  further comprising:
 an implanted device for wirelessly transmitting data representative of said at least one neurological signal from a subject; and   a receiver for receiving the transmitted data wherein said receiver is operationally coupled to at least one of the first processor and the second processor.   
     
     
         34 . The system of  claim 33  further comprising an output device for communicating information related to the estimate of the second propensity to the subject.