Time-qualified reference values for 24 h ambulatory blood pressure monitoring.
BACKGROUND
The development of automatic instrumentation for ambulatory blood pressure monitoring makes it possible to follow the time-course of blood pressure variation over 24h or more in large groups of individuals. Whenever samples from a reference group of individuals are available, one may construct a prediction interval that is expected to include any single future observation from the reference population, with a specified confidence. Alternatively, the reference interval may consist of a tolerance interval that will include at least a specified proportion of the population with a stated confidence.


OBJECTIVE
To examine prospectively whether a new, combined tolerance-hyperbaric test approach of establishing tolerance intervals for the circadian variability of blood pressure as a function of gestational age and then computing the hyperbaric index as a measure of blood pressure excess provides high sensitivity and specificity in the early identification of pregnant women who subsequently will develop gestational hypertension or pre-eclampsia.


METHODS
We used data sampled for 48 h from 148 normotensive men and women to compute and compare time-specified tolerance and prediction intervals for blood pressure. Once the threshold, given by the upper limit of the tolerance interval, was available, the hyperbaric index, as a measure of blood pressure excess, could be calculated by numerical integration as the total area of any given patient
Hermida
R C
RC
Bioengineering & Chronobiology Laboratories, E.T.S.I. Telecommunicación, University of Vigo, Campus Universitario, Vigo, 36200, Spain. rhermida@tsc.uvigo.es
D018660:Blood Pressure Monitoring, Ambulatory; D005260:Female; D006801:Humans; D008297:Male; D011247:Pregnancy; D012016:Reference Values; D013223:Statistics as Topic; D013997:Time Factors