Fetal data processing system and method employing a time-frequency representation

Abstract

A fetal data processing system and method and a fetal monitor and method for monitoring the condition of a fetus are disclosed. A fetal heart rate time series is received and sampled. A non-linear time-frequency transformation is performed to generate a time-frequency representation of the fetal heart rate time series for heart rate time series data spanning a time period which is preferably less than ten seconds. Analysis of fetal heart rate and fetal heart rate variability and other available data is performed to evaluate fetal well-being. Because of the high time resolution of the transformation, short-term transient variations in heart rate and heart rate variability are considered in the analysis.

1 . A fetal data processing method comprising: 
 providing a fetal heart rate moniter;    receiving a signal indicative of fetal heart rate time data for the fetus from the monitor, said fetal heart rate time data indicating heart rate of the fetus over time;    performing a non-linear time-frequency transformation on the fetal heart rate time data to generate a frequency domain representation for the fetal heart rate time data; and    analyzing the frequency domain representation to indicate a condition of the fetus related to the fetal heart rate time data.    
     
     
         2 . The method of    claim 1    further comprising indicating transient change in fetal heart rate variability.  
     
     
         3 . The method of    claim 1    further comprising indicating transient change in fetal heart rate.  
     
     
         4 . The method of    claim 1    wherein the fetal heart rate time data is also used to perform the indicating step.  
     
     
         5 . The method of    claim 1    wherein a uterine contraction signal is also used to perform the indicating step.  
     
     
         6 . The method of    claim 1    wherein a fetal movement signal is also used to perform the indicating step.  
     
     
         7 . The method of    claim 1    further comprising predicting outcome for the fetus.  
     
     
         8 . The method of    claim 1    wherein the indicating step comprises applying a set of classification rules to fetal data.  
     
     
         9 . The method of    claim 1    wherein the indicating step comprises applying a pattern of fetal data to a neural network.  
     
     
         10 . The method of    claim 1    wherein the indicating step comprises analyzing the time-frequency representation in plural frequency bands.  
     
     
         11 . The method of    claim 1    wherein the time-frequency representation spans a frequency range from 0.02 Hz to 1.1 Hz.  
     
     
         12 . The method of    claim 1    wherein the indicating step comprises computing areas under the time-frequency representation.  
     
     
         13 . The method of    claim 1    wherein the time-frequency representation is generated for fetal heart rate time data from a time period of less than ten seconds.  
     
     
         14 . The method of    claim 1    further comprising sampling the fetal heart rate time data at a frequency greater than 2 Hz.  
     
     
         15 . The method of    claim 1    further comprising displaying in real time variables used to indicate the condition of the fetus.  
     
     
         16 . The method of    claim 1    further comprising displaying a three-dimensional plot of the time-frequency representation.  
     
     
         17 . The method of    claim 16   , wherein the three-dimensional plot of the time-frequency representation is updated with frequency amplitude data at 1.0 second intervals.  
     
     
         18 . The method of    claim 16   , wherein the three-dimensional plot of the time-frequency representation is color coded to indicate different conditions.  
     
     
         19 . The method of    claim 1    further comprising generating recommendations regarding fetal well-being.  
     
     
         20 . The method of    claim 1    wherein the non-linear time-frequency representation is performed for each sampling period over which fetal heart rate time date is collected where the sampling period is not to exceed 10 seconds.  
     
     
         21 . The method of    claim 1    wherein the time-frequency representation is generated using a smoothed Wigner distribution.  
     
     
         22 . A fetal data processing system comprising: 
 a fetal heart rate monitor;    an input that receives fetal heart rate time data for a fetus from the monitor, said fetal heart rate time data indicating heart rate of the fetus over time; and    a processing system comprising a processor and a memory, the processor running under control of a program stored in the memory that receives the fetal heart rate time data, and further comprising a subsystem that samples the fetal heart rate time data over a sample time period that does not exceed 10 seconds such that sampled fetal heart time data is generated, the system performing a time-frequency transformation on the sampled fetal heart rate time data, said transformation generating a frequency-domain representation for the fetal heart rate time data.    
     
     
         23 . The fetal data processing system of    claim 22    further comprising a classifying subsystem that analyzes the fetal heart rate time data to indicate the condition of the fetus.  
     
     
         24 . The fetal data processing system of    claim 23    wherein the classifying subsystem also analyzes a uterine contraction signal to indicate the condition of the fetus.  
     
     
         25 . The fetal data processing system of    claim 23    wherein the classifying subsystem also analyzes a fetal movement signal to indicate the condition of the fetus.  
     
     
         26 . The fetal data processing system of    claim 23    wherein the classifying subsystem analyzes the time-frequency representation in plural frequency bands.  
     
     
         27 . The fetal data processing system of    claim 23    wherein the classifying subsystem applies a set of classifying rules to a pattern of fetal data to classify the fetal data.  
     
     
         28 . The fetal data processing system of    claim 23    wherein the classifying subsystem comprises at least one neural network for receiving a pattern of fetal data to classify the fetal data.  
     
     
         29 . The fetal data processing system of    claim 23    wherein the classifying subsystem predicts an outcome for the fetus.  
     
     
         30 . The fetal data processing system of    claim 22    further comprising a display for displaying in real time variables used to indicate the condition of the fetus.  
     
     
         31 . The fetal data processing system of    claim 22    further comprising a display controller for selecting for display in real time variables used to predict outcome for the fetus.  
     
     
         32 . The fetal data processing system of    claim 22    wherein the frequency-domain representation is analyzed to indicate, based on the analysis of the frequency-domain representation, a condition of the fetus related to the sampled fetal heart rate time data.