Document Detail

Inaccuracy of noninvasive estimates of VD/VT in clinical exercise testing.
MedLine Citation:
PMID:  7956406     Owner:  NLM     Status:  MEDLINE    
To evaluate the accuracy of noninvasive estimates of VD/VT in clinical exercise testing, we compared measurements of standard VD/VT with estimates based either on end-tidal CO2 (VD/VTET) or a published estimate of arterial PCO2 (VD/VTest) at peak exercise in 68 patients. Using regression analysis, we identified highly significant differences (p < 0.001) between each method and VD/VTstand across a broad range of observed VD/VT. Assuming a normal exercise VD/VT < or = 0.30, estimate methods were specific but were insensitive (50 percent for VD/VTET and 57 percent for VD/VTest) for identifying patients with abnormal gas exchange during exercise. Separate analysis of subgroups based on resting pulmonary function did not identify any group for which either method was acceptable. Our analysis showed that errors in estimating PaCO2, which are amplified by the Bohr equation when calculating VD/VT, are responsible for the inaccuracies of each noninvasive method. We conclude that noninvasive estimates of PaCO2 cannot replace measured arterial PCO2 for calculation of VD/VT during exercise.
D A Lewis; K E Sietsema; R Casaburi; D Y Sue
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Publication Detail:
Type:  Comparative Study; Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Chest     Volume:  106     ISSN:  0012-3692     ISO Abbreviation:  Chest     Publication Date:  1994 Nov 
Date Detail:
Created Date:  1994-12-09     Completed Date:  1994-12-09     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  0231335     Medline TA:  Chest     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  1476-80     Citation Subset:  AIM; IM    
Division of Respiratory and Critical Care Physiology and Medicine, Harbor-UCLA Medical Center, Torrance 90509.
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MeSH Terms
Exercise Test* / instrumentation,  methods,  statistics & numerical data
Exercise Tolerance
Linear Models
Middle Aged
Partial Pressure
Pulmonary Gas Exchange
Reproducibility of Results
Respiratory Dead Space
Respiratory Mechanics*
Sensitivity and Specificity
Tidal Volume

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

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