Water drinking in the management of orthostatic intolerance due to orthostatic hypotension, vasovagal syncope and the postural tachycardia syndrome

Abstract

Water drinking recently has been shown to raise blood pressure in normal subjects and in patients with autonomic failure who have orthostatic hypotension. However, in normal young subjects, ingestion of approximately 500 ml has no pressor effect; but in older subjects there is an increase in blood pressure. An even greater rise in blood pressure occurs in cases with autonomic failure. The possible mechanisms responsible for the pressor response to water include neural and humoral factors; fluid redistribution also needs to be considered. This review will concentrate on the water pressor response in normal subjects and different groups of patients with autonomic diseases who have orthostatic intolerance, on the mechanisms that could be involved, and on whether this pressor response may be used in the management of orthostatic hypotension, vasovagal syncope and the postural tachycardia syndrome.

Choroidal Thickness Change after Water Drinking Is Greater in Angle Closure than in Open Angle Eyes

“…The mechanism by which it increases blood pressure (BP) is thought to be increased sympathetic tone. 38 Present evidence suggests that both higher IOP and increase in BP may result from increased peripheral vascular resistance, along with a minor reduction in plasma osmolality. [39][40][41][42] It is now known that the thickness of the choroid is altered by changes in BP and IOP.…”

Does non-pharmacological treatment affect outcomes in dysautonomic syndromes?

“…Indeed, this is not the most important consequence of the water ingestion on dysautonomic patients. When water is drunk, a pressor response is observed, reaching the maximum effect around 20 min after the ingestion [12,13]. This consequence was demonstrated in older normal subjects and in patients with autonomic failure.…”

“…It was observed that water ingestion increased orthostatic tolerance to head--up tilt test combined with lower body negative pressure [12]. Its effect alone in vasovagal syncope remains unclear but, in the postural orthostatic tachycardia syndrome, water ingestion attenuates the postural rise in heart rate (HR) and in patients with autonomic failure, and also reduces the degree of orthostatic and postprandial hypotension [13].…”

Acute effect of oral water intake during exercise on post-exercise hypotension

“…Water drinking has been recognized as a powerful treatment for orthostatic and postprandial hypotension in patients by virtue of its profound pressor response. 11,30 Oral water intake also has effects on BP and HR in normal subjects, although the actions are more subtle. 13,31 The water-induced pressor response appears to be mediated through sympathetic nervous activation.…”