SEASONAL BLOOD-PRESSURE VARIATIONS IN HYP ERTENSIVE PATIENTS

Blood pressure (BP) was measured once every month during one year in 8 0 hypertensive outpatients. An orthostatic test was performed in winte r and another during summer. The collective was aged 65 +/- 13 years ( m +/- SD) and presented an elevated prevalence of diabetes mellitus, c ardiac failure, and coronary, cerebral and arterial insufficiency. Diu retics, betablockers, converting enzyme inhibitors and calcium channel blockers were used by 31 patients as monotherapy and by 49 patients i n association. During summer a significantly lower seated BP was found (144.1/79.4 mm Hg vs 150.8/82.9 mm Hg in winter, p<0.001). One fourth of the patients did not show this diminution. On the basis of the WHO criteria of BP definition, 31% of the patients could be considered hy pertensive in winter vs 16% in summer and 28% as normotensive in winte r vs 43% in summer (p<0.05). The summer reduction in BP depended on po sition. It was less marked in seated position (-5.3/-2.7 mm Hg) than i n lying (-61-5.1 mm Hg) or even in standing position (-10.8/-5.1 mm Hg ). The orthostatic test induced a greater immediate fall in systolic B P in summer than in winter (-14.4 vs -9.6 mm Hg, p<0.001), more orthos tatic hypotensive episodes defined as a systolic BP fall of 20 mm Hg o r more (34% of patients vs 20% in winter, p = 0.05) and more signs of reduced cerebral perfusion (14% vs 7.5% in winter, NS). Diabetic patie nts and patients treated by diuretic and vasodilator drugs are particu larly exposed to orthostatic hypotension in summer. Betablockers can m inimize this risk. It is conceivable, but not proven, that the summer BP decrease represents an increased risk of falls or cerebral or heart attacks.