CHARACTERIZING THE STATISTICAL PROPERTIES OF A BIOLOGICAL SIGNAL

摘要

The statistical properties of a biological signal intermittently obscured by a relatively independent biological process are estimated by noting the time intervals during which the obscuring process is occurring. From the time intervals, a windowing function is constructed which makes a transition from one towards zero as the process obscures the signal and a transition towards one as the process terminates. Thereafter, a statistical characterization is performed in which the windowing function is used to weight the relative contributions of corresponding segments of the biological signal. In preferred embodiments, the statistical properties include the autocorrelation function and power spectrum of biological signals such as heart rate and blood pressure. The invention is applicable also to estimating the crosscorrelation and transfer function of a first signal intermittently obscured by a first process and a second signal intermittently obscured by a second process in which each of the signals are relatively independent of each of the obscuring processes. When the biological signal is heart rate, the obscuring process may be the occurrence of ectopic beats. Intervals which contain ectopic beats are treated as though they are missing. In this way, data which might otherwise be unusable by virtue of ectopic beats can become useful for assessing the status of the biological system.