Water Drinking to Prevent Orthostatic Hypotension and Neurally Mediated Syncope: Mechanisms and Benefits
Water drinking is now recognized as having pressor effects even in normal subjects. In young subjects there is no change in blood pressure after water drinking, but in older subjects there is a rise in systolic blood pressure . An even greater rise-in some cases over 30 mmHg-occurs in patients with orthostatic hypotension due to chronic autonomic failure (Fig. 1) . Water alone, therefore, has appreciable cardiovascular effects in both normal and diseased man. The mechanisms of the pressor response remain unclear. Recognition of these effects of water is of importance in studies of cardiovascular and autonomic function. This review relates to the physiology and pathophysiology of water drinking, its ability to reduce orthostatic hypotension in autonomie failure, and its potential benefit when intermittent autonomie dysfunction causes orthostatic intolerance or syncope.
KeywordsPressor Response Multiple System Atrophy Muscle Sympathetic Nerve Activity Autonomic Failure Lower Body Negative Pressure
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