Salt supplement increases plasma volume and orthostatic tolerance in patients with unexplained syncope.

Elsayed, H M; Hainsworth, R.

doi:10.1136/hrt.75.2.134

Cited by 249 publications

(174 citation statements)

References 17 publications

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“…6,71 Similarly, expansion of plasma volume following salt supplementation improves orthostatic tolerance. 72,73 Thus, it would be expected that salt depletion and/or small plasma volumes would predispose to orthostatic hypotension. 66 In patients with chronic SCI, there is evidence of impaired water and sodium retention in the seated position, and limited salt and water intake.…”

Section: Altered Salt and Water Balancementioning

confidence: 99%

Orthostatic hypotension following spinal cord injury: understanding clinical pathophysiology

2005

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Motor and sensory deficits are well-known consequences of spinal cord injury (SCI). During the last decade, a significant number of experimental and clinical studies have focused on the investigation of autonomic dysfunction and cardiovascular control following SCI. Numerous clinical reports have suggested that unstable blood pressure control in individuals with SCI could be responsible for their increased cardiovascular mortality. The aim of this review is to outline the incidence and pathophysiological mechanisms underlying the orthostatic hypotension that commonly occurs following SCI. We describe the clinical abnormalities of blood pressure control following SCI, with particular emphasis upon orthostatic hypotension. Possible mechanisms underlying orthostatic hypotension in SCI, such as changes in sympathetic activity, altered baroreflex function, the lack of skeletal muscle pumping activity, cardiovascular deconditioning and altered salt and water balance will be discussed. Possible alterations in cerebral autoregulation following SCI, and the impact of these changes upon cerebral perfusion are also examined. Finally, the management of orthostatic hypotension will be considered.

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Section: Altered Salt and Water Balancementioning

confidence: 99%

Orthostatic hypotension following spinal cord injury: understanding clinical pathophysiology

2005

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“…Changes of this magnitude in patients with attacks of syncope or presyncope are associated with considerable symptomatic improvements. 19 Subjects with lower orthostatic tolerance had the greatest improvement in orthostatic tolerance. In an earlier study, cardiovascular and hematologic responses to tilt testing were examined after 26 hours of dehydration and after oral rehydration.…”

Section: Schroeder Et Al Water Drinking and Orthostatic Tolerancementioning

confidence: 99%

Water Drinking Acutely Improves Orthostatic Tolerance in Healthy Subjects

et al. 2002

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Background-Orthostatic symptoms and syncope are common, even in apparently healthy subjects. In patients with severe autonomic dysfunction, water drinking elicits an acute pressor response and improves orthostatic hypotension. We tested the hypothesis that water drinking also improves orthostatic tolerance in healthy subjects. Methods and Results-In a randomized, controlled, crossover fashion, 13 healthy subjects (9 men, 4 women, 31Ϯ2 years) ingested 500 mL and 50 mL of mineral water 15 minutes before head-up tilt on two separate days. Finger blood pressure, brachial blood pressure, heart rate, thoracic impedance, and blood flow velocity in the brachial artery and the middle cerebral artery were measured. Orthostatic tolerance was determined as the time to presyncope during a combined protocol of 20 minutes of 60°head-up tilt alone, followed by additional increasing steps of lower body negative pressure (Ϫ20, Ϫ40, and Ϫ60 mm Hg for 10 minutes each or until presyncope). Drinking 500 mL of water improved orthostatic tolerance by 5Ϯ1 minute (range, Ϫ1 to ϩ11 minutes, PϽ0.001). After drinking 500 mL of water, supine mean blood pressure increased slightly (PϽ0.01) as the result of increased peripheral resistance (PϽ0.01). It also blunted both the increase in heart rate and the decrease in stroke volume with head-up tilt. Cerebral blood flow regulation improved after water drinking. Conclusions-Water drinking elicits an acute hemodynamic response and changes in cerebrovascular regulation in healthy subjects. These effects are associated with a marked improvement in orthostatic tolerance.

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“…We have developed a sensitive and reproducible measure of orthostatic tolerance which determines the time to onset of presyncope in a progressive test of head-up tilt combined with lower body suction . This test is able to distinguish results from patients with unexplained syncope from those from normal controls and has been used to assess possible benefits of therapeutic interventions El-Sayed & Hainsworth, 1996).…”

Section: B L M T L N a N G L A N D R H A I N S W O R T Hmentioning

confidence: 99%

“…We have reported that orthostatic tolerance is significantly correlated with plasma and blood volumes (El-Sayed & Hainsworth, 1995) and that, if these can be expanded by salt loading, orthostatic tolerance improves (El-Sayed & Hainsworth, 1996). Since exercise training is also known to increase plasma and blood volumes (Saltin et al 1968), if all other things are equal, orthostatic tolerance should also improve.…”

Section: Introductionmentioning

confidence: 99%

Effects of moderate exercise training on plasma volume, baroreceptor sensitivity and orthostatic tolerance in healthy subjects

Mtinangi

Hainsworth

1999

Experimental Physiology

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The effect of physical training on an individual's ability to withstand an orthostatic stress is unclear. This study was undertaken to determine the effects on orthostatic tolerance in healthy volunteers of training at a level appropriate for unfit subjects and cardiorespiratory patients. In 11 asymptomatic, untrained subjects the following assessments were made: plasma volume by Evans Blue dye dilution and blood volume derived from haematocrit; carotid baroreceptor sensitivity from the slope of the regression of change in cardiac interval against pressure applied to a neck chamber; orthostatic tolerance as time to presyncope in a test of head-up tilting combined with lower body suction; exercise test relating heart rate to oxygen consumption. Subjects were then given a training schedule (.5BX/XBX, Royal Canadian Air Force) involving 11-12 min of mixed exercises per day until an age/sex related 'target' was reached. Following training all subjects showed evidence of improved fitness, seen as decreases in heart rate at an oxygen uptake (V0J of 1.5 1 min-' and in the elevation of the regression line between hearr rate and Vo,. All also had increases in plasma and blood volumes and decreases in baroreceptor sensitivity. Seven of the subjects showed increases in orthostatic tolerance. Improvement in orthostatic tolerance was related to a low initial tolerance, and was associated with increases in plasma volume and decreases in baroreceptor sensitivity. These results show that moderate exercise training increases orthostatic tolerance in subjects who do not already have a high initial tolerance and suggest that training may be of value in the management of untrained patients with attacks of syncope due to orthostatic intolerance.

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Salt supplement increases plasma volume and orthostatic tolerance in patients with unexplained syncope.

Cited by 249 publications

References 17 publications

Orthostatic hypotension following spinal cord injury: understanding clinical pathophysiology

Orthostatic hypotension following spinal cord injury: understanding clinical pathophysiology

Water Drinking Acutely Improves Orthostatic Tolerance in Healthy Subjects

Effects of moderate exercise training on plasma volume, baroreceptor sensitivity and orthostatic tolerance in healthy subjects

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