Document Detail

Isoflurane anaesthesia (0.6 MAC) and hypoxic ventilatory responses in humans.
MedLine Citation:
PMID:  7725878     Owner:  NLM     Status:  MEDLINE    
In order to evaluate the difference between poikilo-capnic (no CO2 added to inspired gas) and iso-capnic (CO2 added to keep end-tidal CO2 constant) hypoxic ventilatory responses (HVR) awake and during 0.6 MAC isoflurane anaesthesia, seven cardio-pulmonary healthy patients were investigated. Pneumotachography and capnography were used before and during hypoxia (end-tidal O2 tension approx. 7 kPa). In the awake state, poikilo-capnic hypoxic challenges resulted in an increased HVR as indicated by a VE that on average increased by 1.4 +/- 1.0 (mean +/- s.d.) l.min-1, whereas the iso-capnic hypoxic challenges resulted in a VE increase that was 4.7 +/- 2.3 l.min-1 on average. In the anaesthetized state, the corresponding value during poikilocapnia was 1.3 +/- 0.8 l.min-1 (88% of the awake responses, n.s.) and during iso-capnia 2.3 +/- 1.4 l.min-1 (49% of the awake, P < 0.02). Awake HVR was achieved by greater tidal volumes during poikilocapnia as well as during isocapnic challenges, while respiratory rates were unchanged. In the anaesthetized state, during poikilocapnia, however, HVR was mediated by an increased respiratory rate, (from 17.5 +/- 1.7 breath.min-1 to 20.2 +/- 2.2) and during isocapnia by a combination of increased rate (from 17.1 +/- 1.9 breath.min-1 to 19.1 +/- 1.8) and tidal volume (from 496 +/- 80 to 560 +/- 83 ml). It is concluded that poikilocapnic HVR is maintained at 0.6 MAC isoflurane whereas iso-capnic HVR is depressed by 50%.(ABSTRACT TRUNCATED AT 250 WORDS)
D Sjögren; A Sollevi; A Ebberyd; S G Lindahl
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Acta anaesthesiologica Scandinavica     Volume:  39     ISSN:  0001-5172     ISO Abbreviation:  Acta Anaesthesiol Scand     Publication Date:  1995 Jan 
Date Detail:
Created Date:  1995-05-22     Completed Date:  1995-05-22     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  0370270     Medline TA:  Acta Anaesthesiol Scand     Country:  DENMARK    
Other Details:
Languages:  eng     Pagination:  17-22     Citation Subset:  IM    
Department of Anaesthesiology and Intensive Care, Karolinska Hospital & Institute, Stockholm, Sweden.
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MeSH Terms
Anesthesia, Inhalation*
Anoxia / physiopathology*
Blood Pressure / physiology
Carbon Dioxide / administration & dosage,  analysis
Heart Rate / physiology
Inhalation / physiology
Isoflurane* / administration & dosage
Monitoring, Intraoperative
Oxygen / administration & dosage,  analysis,  blood
Respiration / physiology*
Tidal Volume / physiology
Wakefulness / physiology
Reg. No./Substance:
124-38-9/Carbon Dioxide; 26675-46-7/Isoflurane; 7782-44-7/Oxygen

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

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