Document Detail

Elevating cardiac pre-load on left-ventricular diastolic function and volume during heat stress: implications toward tolerance during a hemorrhagic insult.
MedLine Citation:
PMID:  25163916     Owner:  NLM     Status:  Publisher    
Volume loading normalizes tolerance to a simulated hemorrhagic challenge during heat stress, relative to thermoneutral conditions; however, the mechanism(s) are unknown. This project tested two unique hypotheses; the elevation of central blood volume via volume loading while heat stressed would: 1) increase left ventricular diastolic function, and 2) preserve left ventricular end-diastolic volume (LVEDV) during a simulated hemorrhagic challenge induced by lower-body negative pressure (LBNP). Left ventricular diastolic function was evaluated in nine subjects during the following conditions: thermoneutral, heat stress, and heat stress after volume loading sufficient to return ventricular filling pressures towards thermoneutral levels. LVEDV was measured during the aforementioned conditions prior to and during LBNP. Heat stress did not change diastolic function. Subsequent volume infusion elevated diastolic function, specifically early diastolic mitral annular tissue velocity (E') and early diastolic propagation velocity (E) relative to both thermoneutral and heat stress conditions (P<0.05 for both). Heat stress reduced LVEDV (P<0.05), while volume infusion returned LVEDV to thermoneutral levels. The reduction in LVEDV to LBNP was similar between thermoneutral and heat stress conditions, whereas the reduction after volume infusion was attenuated relative to both conditions (P<0.05). Absolute LVEDV during LBNP after volume loading was appreciably greater relative to the same level of LBNP during heat stress alone. Thus, rapid volume infusion during heat stress increased indices of left ventricular diastolic function and attenuated the reduction in LVEDV during LBNP, both of which may serve as mechanisms by which volume loading improves tolerance to a combined hyperthermic and hemorrhagic challenge.
R Matthew Brothers; Redi Pecini; Morten Dalsgaard; Morten Bundgaard-Nielsen; Thad E Wilson; Niels H Secher; Craig G Crandall
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Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2014-8-27
Journal Detail:
Title:  American journal of physiology. Regulatory, integrative and comparative physiology     Volume:  -     ISSN:  1522-1490     ISO Abbreviation:  Am. J. Physiol. Regul. Integr. Comp. Physiol.     Publication Date:  2014 Aug 
Date Detail:
Created Date:  2014-8-28     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  100901230     Medline TA:  Am J Physiol Regul Integr Comp Physiol     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
Copyright Information:
Copyright © 2014, American Journal of Physiology - Regulatory, Integrative and Comparative Physiology.
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