Document Detail

Skin cooling aids cerebrovascular function more effectively under severe than moderate heat stress.
MedLine Citation:
PMID:  19946700     Owner:  NLM     Status:  MEDLINE    
Skin surface cooling has been shown to improve orthostatic tolerance; however, the influence of severe heat stress on cardiovascular and cerebrovascular responses to skin cooling remains unknown. Nine healthy males, resting supine in a water-perfusion suit, were heated to +1.0 and +2.0 degrees C elevation in body core temperature (T (c)). Blood flow velocity in the middle cerebral artery (transcranial Doppler ultrasound), mean arterial pressure (MAP; photoplethysmography), stroke volume (SV; Modelflow), total peripheral resistance (TPR; Modelflow), heart rate (HR; ECG) and the partial pressure of end-tidal carbon dioxide (P(ET)CO(2)) were measured continuously during 1-min baseline and 3-min lower body negative pressure (LBNP, -15 mm Hg) when heated without and again with skin surface cooling. Nine participants tolerated +1 degrees C and six participants reached +2 degrees C. Skin cooling elevated (P = 0.004) MAP ~4% during baseline and LBNP at +1 degrees C T (c). During LBNP, skin cooling increased SV (9%; P = 0.010) and TPR (0.9 mm Hg L(-1) min, P = 0.013) and lowered HR (13 b min(-1), P = 0.012) at +1 degrees C T (c) and +2 degrees C T (c) collectively. At +2 degrees C T (c), skin cooling elevated P(ET)CO(2) ~4.3 mm Hg (P = 0.011) and therefore reduced cerebral vascular resistance ~0.1 mm Hg cm(-1) s at baseline and LBNP (P = 0.012). In conclusion, skin cooling under severe heating and mild orthostatic stress maintained cerebral blood flow more effectively than it did under moderate heating, in conjunction with elevated carbon dioxide pressure, SV and arterial resistance.
Rebekah A I Lucas; Philip N Ainslie; Jui-Lin Fan; Luke C Wilson; Kate N Thomas; James D Cotter
Publication Detail:
Type:  Journal Article     Date:  2009-11-28
Journal Detail:
Title:  European journal of applied physiology     Volume:  109     ISSN:  1439-6327     ISO Abbreviation:  Eur. J. Appl. Physiol.     Publication Date:  2010 May 
Date Detail:
Created Date:  2010-04-13     Completed Date:  2010-08-11     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  100954790     Medline TA:  Eur J Appl Physiol     Country:  Germany    
Other Details:
Languages:  eng     Pagination:  101-8     Citation Subset:  IM    
Department of Physiology, University of Otago, Dunedin, New Zealand.
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MeSH Terms
Blood Flow Velocity / physiology
Blood Pressure / physiology
Body Temperature Regulation*
Cerebrovascular Circulation / physiology*
Cold Temperature*
Heart Rate / physiology
Heat-Shock Response / physiology*
Lower Body Negative Pressure
Middle Cerebral Artery / physiology
Regional Blood Flow / physiology
Skin Temperature / physiology*
Supine Position / physiology
Vascular Resistance / physiology
Young Adult

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