Effects of chronic beta-blockade on intra-arterial blood pressure during motor car driving.

Continuous intra-arterial blood pressure recordings during motor car driving were performed in 15 patients with untreated essential hypertension, using the "Oxford" recording technique. Each subject was an experienced driver who used his car every day, and for the study drove from his work place to the hospital during the later afternoon. This drive took place in urban traffic and the average duration was 20.9 minutes. Blood pressure during car driving was remarkably stable, and the average systolic and diastolic pressures were similar to the mean daytime pressure. After 16 weeks of treatment with oxprenolol each patient was restudied. Blood pressure during driving had dropped from 176/107 to 160/93 mmHg, but the blood pressure response to driving and blood pressure variation during driving (expressed as the coefficient of variation) were unchanged. After treatment, the mean daytime systolic pressure was lower than the mean pressure during driving, but the relative antihypertensive effect during driving was similar to that observed in the same patients during dynamic exercise on a bicycle ergometer. No drug-induced side effects occurred and there were no apparent effects on driving ability. Chronic treatment with oxprenolol reduced blood pressure during car driving without affecting the normal blood pressure response to driving.