Document Detail

Cardiorespiratory failure in rat induced by severe inspiratory resistive loading.
MedLine Citation:
PMID:  17138835     Owner:  NLM     Status:  MEDLINE    
The mechanisms underlying acute respiratory failure induced by respiratory loads are unclear. We hypothesized that, in contrast to a moderate inspiratory resistive load, a severe one would elicit central respiratory failure (decreased respiratory drive) before diaphragmatic injury and fatigue. We also wished to elucidate the factors that predict endurance time and peak tracheal pressure generation. Anesthetized rats breathed air against a severe load ( approximately 75% of the peak tracheal pressure generated during a 30-s occlusion) until pump failure (fall in tracheal pressure to half; mean 38 min). Hypercapnia and hypoxemia developed rapidly ( approximately 4 min), coincident with diaphragmatic fatigue (decreased ratio of transdiaphragmatic pressure to peak integrated phrenic activity) and the detection in blood of the fast isoform of skeletal troponin I (muscle injury). At approximately 23 min, respiratory frequency and then blood pressure fell, followed immediately by secondary diaphragmatic fatigue. Blood taken after termination of loading contained cardiac troponin T (myocardial injury). Contrary to our hypothesis, diaphragmatic fatigue and injury occurred early in loading before central failure, evident only as a change in the timing but not the drive component of the central respiratory pattern generator. Stepwise multiple regression analysis selected changes in mean arterial pressure and arterial Pco(2) during loading as the principal contributing factors in load endurance time, and changes in mean arterial pressure as the principal contributing factor in peak tracheal pressure generation. In conclusion, the temporal development of respiratory failure is not stereotyped but depends on load magnitude; moreover respiratory loads induce cardiorespiratory, not just respiratory, failure.
Jeremy A Simpson; Steve Iscoe
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2006-11-30
Journal Detail:
Title:  Journal of applied physiology (Bethesda, Md. : 1985)     Volume:  102     ISSN:  8750-7587     ISO Abbreviation:  J. Appl. Physiol.     Publication Date:  2007 Apr 
Date Detail:
Created Date:  2007-04-05     Completed Date:  2007-05-22     Revised Date:  2013-09-26    
Medline Journal Info:
Nlm Unique ID:  8502536     Medline TA:  J Appl Physiol (1985)     Country:  United States    
Other Details:
Languages:  eng     Pagination:  1556-64     Citation Subset:  IM    
Department of Physiology, Queen's University, Kingston, Ontario, Canada.
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MeSH Terms
Airway Obstruction / complications*,  physiopathology*
Airway Resistance*
Diaphragm / physiopathology*
Heart Failure / etiology*,  physiopathology*
Rats, Sprague-Dawley
Respiratory Insufficiency
Respiratory Mechanics*

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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