ESTIMATE OF 24-HOUR MEAN AND STANDARD DEVIATION (SD) BY INTERMITTENT SAMPLING OF BLOOD PRESSURE SEGMENTS.

24-h intra-arterial blood pressure (BP) mean and SD have been shown to improve the diagnostic and prognostic evaluation of hypertension. The authors analyzed the estimates of 24-h mean variance and SD in 16 subjects, obtained by collecting several-minute-long segments of intra-arterial BP signal regularly sampled every 30 min over 24 h. The true 24-h BP mean value and variance were calculated by beat-to-beat sampling. Then each BP trace was split into consecutive records over 30 min. Each record was subdivided into a sample segment, S min long, and an inter-sample segment, I min long. Mean variance and SD computed over the sample segments were compared with the true 24-h values: the various S-I pairs achieved estimates of mean and SD with errors less than 1 mm Hg.