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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

Blood Pressure Monitoring, Ambulatory↗
PubMed1989

[Differences in reference values in 2-dimensional echocardiography in men and women].

A total of 126 voluntary blood donors (90 men, mean age 30 +/- 0.5 yrs, and 36 women, mean age 34 +/- 0.5 yrs) were examined to establish standards for two-dimensional echocardiography. The maximal width of the left ventricle (LV), the thickness of the interventricular septum (IVS) and of the posterior wall (PW) during systole (s) and diastole (d), the systolic dimension of the left atrium (LA) and the diastolic dimension of the aorta (Ao) and right ventricle (RV) were determined. The measurements were performed from the short parasternal axis. Significantly larger dimensions for LV(s), LV(d), IVS(s), IVS(d)(p less than 0.001) and for LA(s) and PW(d) (p less than 0.01) were measured in men as compared to women. No significant intersexual differences were observed in the other parameters studied or in their calculated ratios (LA/Ao, IVS/PW, ejection fraction and fractional shortening LV, IVS, PW). It can be concluded that exact measurements in correlation studies with two-dimensional echocardiography require corresponding parameter values for body surface area.

Adult↗
PubMed1997

Published models and local data can bridge the gap between reference values of lung function for children and adults.

The aim of this study was to create reference equations for pulmonary function tests (PFTs) that span the age range from childhood to young adulthood. PFT results (forced vital capacity (FVC), forced expiratory volume in one second (FEV1), ratio of FEV1 to FVC (FEV1/FVC), total lung capacity (TLC), transfer factor) of 348 healthy 13-24 yr old Caucasian never-smokers from a local population study were compared with 13 selected sets of published reference equations. Predicted and observed PFT results differed significantly for 63 of 92 reference equations tested, and most equations accounted poorly for the increase in PFT variables which takes place during adolescence. We selected the equations with the best fit and adjusted their parameters, so that the level and variance of predicted values agreed with the local data. For subjects older than 18 yrs, we selected the European Community for Steel and Coal (ECSC) equations. For subjects younger than 18 yrs, we chose European summary equations for FVC, FEV1, and FEV1/FVC, and recent British equations for TLC and transfer factor. The customized reference equations are the best available (maximum likelihood) for analysing PFTs of patients tested in our laboratory. Our approach can be used whenever generally accepted reference equations are lacking and a local sample of normal subjects is available.

Adolescent↗