Document Detail

Hypoxia, not hypercapnia, induces cardiorespiratory failure in rats.
MedLine Citation:
PMID:  24566393     Owner:  NLM     Status:  Publisher    
Mechanical respiratory loads induce cardiorespiratory failure, presumably by increasing O2 demand concurrently with decreases in O2 availability (decreased PaO2). We tested the hypothesis that asphyxia alone can cause cardiorespiratory failure ("failure") in pentobarbital-anesthetized rats. We also tested the hypothesis that hypoxia, not hypercapnia, is responsible by supplying supplemental O2 during mechanical loading in a separate group of rats. Asphyxia (mean PaO2 and PaCO2 of 43 and 69mmHg, respectively) resulted in failure, evident as a slowing of mean respiratory frequency (133 to 83 breaths/min) and a sudden and large drop in mean arterial pressure (71 to 47mmHg), after 214±66min (n=16; range 117 to 355min). Neither respiratory drive nor heart rate decreased, indicating that failure was peripheral, not central. Of 8 rats tested after 3h of asphyxia for the presence in blood of cardiac troponin T, all were positive. In an additional 6 rats, normocapnic hypoxia (mean PaCO2 and PaO2 were 39±2.2 and 41±3.1mmHg, respectively) caused failure after an average 205min (range 181 to 275min), no different from that of asphyxic rats. In the 6 rats that breathed O2 during an initially moderate inspiratory resistive load, endurances exceeded 7h (failure occurring only because we increased the load after 6h) and tracheal pressure and left ventricular dP/dt were maintained despite supercarbia (PaCO2>150mmHg). Thus, asphyxia alone can induce failure, the failure is due to hypoxia, not hypercapnia, and hypercapnia has minimal effects on cardiac and respiratory muscle function in the presence of hyperoxia.
J A Simpson; S Iscoe
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Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2014-2-21
Journal Detail:
Title:  Respiratory physiology & neurobiology     Volume:  -     ISSN:  1878-1519     ISO Abbreviation:  Respir Physiol Neurobiol     Publication Date:  2014 Feb 
Date Detail:
Created Date:  2014-2-25     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  101140022     Medline TA:  Respir Physiol Neurobiol     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
Copyright Information:
Copyright © 2014. Published by Elsevier B.V.
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