Document Detail

Comparison of steady state pulmonary diffusing capacity estimates for O2 and CO in dogs.
MedLine Citation:
PMID:  6777846     Owner:  NLM     Status:  MEDLINE    
In view of the fact that the inhomogeneity effects on pulmonary diffusing capacity (DL) estimates are quite different for O2 and for CO, simultaneous determinations of steady-state DLCO and DLO2 were attempted and compared. To this end, pulmonary gas exchange was measured in 17 anesthetized and artificially ventilated dogs, in hypoxia with and without carbon monoxide in inspired gas (FIO2 = 0.12, FICO = 0.0009 to 0.0016). The diffusing capacity estimates were computed by two conventional procedures, the first (Dapp) taking into account the mean alveolar partial pressures and the second (DVDA) the ideal alveolar partial pressures. It was found that the presence of COHb in blood, inevitable in the steady-state DLCO procedure, leads to a marked underestimation of DLO2; therefore DLCO values could only be adequately compared to DLO2 values obtained in the absence of CO from inspired gas. These DLO2 were 18.5 and 33.4 mumol . min-1 . Torr-1 . kg-1 for the mean DappO2 and DVDAO2, respectively, whereas the DLCO values obtained after 15 to 25 min CO inspiration were 30.0 and 83.4 mumol . min-1 . Torr-1 . kg-1 for the mean DappCO and the mean DVDACO, respectively. The salient feature is that with both procedures the mean value of DLCO estimate is higher than the corresponding DLO2 estimate. This finding suggests that in anesthetized, artificially ventilated dogs DappO2 and DVDACO estimates obtained by steady-state procedures in hypoxia are largely influenced by inhomogeneity effects and of limited value for assessment of the diffusing properties of the lung. DappCO and DVDAO2 are also affected by inhomogeneities but to a lesser degree.
J Savoy; M C Michoud; M Robert; J Geiser; P Haab; J Piiper
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Respiration physiology     Volume:  42     ISSN:  0034-5687     ISO Abbreviation:  Respir Physiol     Publication Date:  1980 Oct 
Date Detail:
Created Date:  1981-02-24     Completed Date:  1981-02-24     Revised Date:  2009-11-11    
Medline Journal Info:
Nlm Unique ID:  0047142     Medline TA:  Respir Physiol     Country:  NETHERLANDS    
Other Details:
Languages:  eng     Pagination:  43-59     Citation Subset:  IM    
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MeSH Terms
Anoxia / physiopathology
Carbon Dioxide*
Pulmonary Diffusing Capacity*
Reg. No./Substance:
124-38-9/Carbon Dioxide; 7782-44-7/Oxygen

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