Document Detail


How does positive end-expiratory pressure decrease pulmonary CO2 elimination in anesthetized patients?
MedLine Citation:
PMID:  10647866     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
In anesthetized, mechanically ventilated patients, 10 cm H2O positive end-expiratory pressure (PEEP10) immediately decreased the CO2 volume exhaled per breath (V(CO2,br)) by 96%, as exhaled tidal volume (VT) decreased to expand functional residual capacity during the first 8 breaths after PEEP10 began. Then, the sustained decrease in V(CO2,br) for over 10 min was due to the 19% decrease in cardiac output (QT, decreased CO2 delivery from tissues to lung) and to the decrease in alveolar ventilation (VA). In turn, decreased VA resulted from decreased VT (loss of inspired volume into the compressible volume of the ventilating circuit) and possibly from increased physiological dead space, due to the potential for new high alveolar ventilation-to-perfusion (VA/Q) lung regions. V(CO2,br) increased and recovered to baseline by 20 min of PEEP10 ventilation because QT increased to augment the CO2 delivery to the lung and alveolar P(CO2) increased (increased mixed venous P(CO2) and tissue CO2 retention) to increase V(CO2,br) while alveolar VT remained depressed. End-tidal P(CO2) (PET(CO2) progressively increased during PEEP10 and did not detect the decrease in V(CO2,br) during PEEP10 ventilation because PET(CO2) does not account for exhaled volume.
Authors:
J L Johnson; P H Breen
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Publication Detail:
Type:  Journal Article; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Respiration physiology     Volume:  118     ISSN:  0034-5687     ISO Abbreviation:  Respir Physiol     Publication Date:  1999 Dec 
Date Detail:
Created Date:  2000-02-22     Completed Date:  2000-02-22     Revised Date:  2009-11-11    
Medline Journal Info:
Nlm Unique ID:  0047142     Medline TA:  Respir Physiol     Country:  NETHERLANDS    
Other Details:
Languages:  eng     Pagination:  227-36     Citation Subset:  IM    
Affiliation:
Department of Anesthesiology, University of California at Irvine, UCI Medical Center, Orange 92868, USA.
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MeSH Terms
Descriptor/Qualifier:
Anesthesia*
Carbon Dioxide / metabolism*
Cardiac Output
Female
Humans
Hydrogen-Ion Concentration
Male
Middle Aged
Positive-Pressure Respiration*
Pulmonary Gas Exchange / physiology*
Reference Values
Tidal Volume
Grant Support
ID/Acronym/Agency:
HL-42637/HL/NHLBI NIH HHS
Chemical
Reg. No./Substance:
124-38-9/Carbon Dioxide

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


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