Water ingestion as prophylaxis against syncope

Item Type:	Article
Title:	Water ingestion as prophylaxis against syncope
Creators Name:	Lu, C.C. and Diedrich, A. and Tung, C.S. and Paranjape, S.Y. and Harris, P.A. and Byrne, D.W. and Jordan, J. and Robertson, D.
Abstract:	Background— Water ingestion raises blood pressure substantially in patients with perturbed autonomic control and more modestly in older subjects. It is unclear whether prophylactic water drinking improves orthostatic tolerance in normal healthy adults. Methods and Results— Twenty-two healthy subjects, 18 to 42 years of age, with no history of syncope underwent head-up tilt-table testing at 60° for 45 minutes or until presyncope or syncope occurred. In their initial test, participants were randomized to either 16 oz (473 mL) of water drinking 5 minutes before tilt-table testing or tilt-table testing alone, with the alternative in a second test on a different day. During the first 30 minutes of tilt, 8 of 22 subjects without water experienced presyncope but only 1 of 22 who had ingested water (P=0.016). Water drinking attenuated the heart rate increase associated with tilt (P<0.001) while accentuating the increase in total peripheral resistance (P=0.012). The average time study participants tolerated head-up tilt was 26% longer after water (41.1±8.1 versus 32.6±14.3 minutes, mean±SD), with a pairwise mean difference of 8.5±14.0 minutes (95% CI, 2.3 to 14.7 minutes; P=0.011). Conclusions— Water enhances tolerance of upright posture. The effect of water is mediated by increased peripheral vascular resistance. Water ingestion may constitute a simple and effective prophylaxis against vasovagal reactions in healthy subjects, such as those associated with blood donation.
Keywords:	Syncope, Water, Tilt Table Test, Orthostatic Hypotension, Norepinephrine
Source:	Circulation
ISSN:	0009-7322
Publisher:	American Heart Association
Volume:	108
Number:	21
Page Range:	2660-2665
Date:	25 November 2003
Official Publication:	https://doi.org/10.1161/01.CIR.0000101966.24899.CB
PubMed:	View item in PubMed

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