DIRECT AND INDIRECT BLOOD-PRESSURE IN NORMOTENSIVE AND HYPERTENSIVE SUBJECTS

Objectives. To compare intrabrachial blood pressure (I-BP) with simult aneously measured contralateral auscultatory (A-)BP in hypertensive an d normotensive subjects. The question was whether differences between direct and indirect BP are influenced by the BP levels. Subjects. Hype rtensive subjects treated with either placebo (n = 10) or metoprolol ( n = 8) and age-matched normotensive subjects (n = 15), selected from a defined patient population waiting for cholecystectomy or hernia repa ir. Measurements were performed pre-induction of anaesthesia. Results. In the hypertensive subjects, cuff systolic BP (SBP) was lower than I -BP by an average of 8 mmHg (placebo-) and 7 mmHg (metoprolol-treated) , whereas diastolic A-BP (A-DBP) was 3 and 7 mmHg higher, respectively . In the normotensive subjects, mean A-SEP and I-SEP agreed closely, w hereas A-DBP was 11 mmHg higher. Thus, SBP differences (i.e. indirect- direct BP) were significantly less and DBP differences significantly g reater in the normotensive than in the hypertensive subjects (P < 0.05 ). Plasma renin activity and adrenalin showed better correlations with A-MBP than with I-MBP. Conclusions. The drift of cuff systolic readin gs fell progressively below the intrabrachial values when BP increased , whilst diastolic cuff values approached the direct pressures. Since A-MBP did not significantly differ from I-MBP in any group, one must a sk whether hypertension would be more correctly defined according to M BP criteria.