The relationship of the 6-min walk test to maximal oxygen consumption in transplant candidates with end-stage lung disease

L. Cahalin, P. Pappagianopoulos, S. Prevost, J. Wain, L. Ginns

Research output: Contribution to journalArticle

166 Scopus citations

Abstract

Study objective: To assess the relationship of distance ambulated during the 6-min walk test (6'WT) to maximal oxygen consumption (V̇O2 max). Design: Multivariate analysis of patient characteristics to V̇O2 max. Setting: Pre-lung transplant evaluation. Patients: 60 patients (22 men, 38 women; mean age, 44 years) with end-stage lung disease (mean FEV1 and forced vital capacity of 0.97 and 1.93, respectively). Measurements and results: The 6'WT was performed on a level hallway surface, and V̇O2 max was obtained during maximal cycle ergometry exercise testing with respiratory gas analysis. Multivariate analysis of patient characteristics (age, sex, weight, FEV1, FVC, diffusing capacity for carbon monoxide (DCO), 6'WT distance ambulated, number of rests per 6'WT, and the maximal heart rate, blood pressure, rate-pressure product, respiratory rate, oxygen saturation, rating of perceived exertion, and amount of supplemental oxygen used during the 6'WT) was performed on two groups of 30 patients each (group A or B) who were randomly assigned to either group by a process of random selection using a computer-generated random numbers program. Distance ambulated was the strongest independent predictor of V̇O2 max (r=0.73; p<0.0001) in both groups, and adding age, weight, and pulmonary function test results (FVC, FEV1, and DCO) to the regression equation increased the correlation coefficient to 0.83. Because of the significant correlation of distance ambulated during the 6'WT to V̇O2 max, the prediction equation obtained from the multivariate analysis of group A, V̇O2 max=0.006 x distance (feet) +3.38, was used to estimate the V̇O2 max of the group B patients. No significant difference was observed between the estimated (x±SD=8.9±2.4 mL/kg/min) and observed (x±SD=9.4±3.8 mL/kg/min) V̇O2 max (mean difference, 0.5 mL/kg/min; SD of the difference=2.88). Conclusions: The distance ambulated during a 6'WT can predict V̇O2 max in patients with end- stage lung disease. The addition of several patient characteristics can increase the ability to predict V̇O2 max and account for more of the variability. Such information is valuable when assessing patient response to therapeutic intervention if respiratory gas analysis is unavailable or impractical.

Original languageEnglish (US)
Pages (from-to)452-459
Number of pages8
JournalCHEST
Volume108
Issue number2
DOIs
StatePublished - Jan 1 1995
Externally publishedYes

Keywords

  • exercise test
  • exercise tolerance
  • lung disease
  • oxygen consumption
  • transplantation
  • walking

ASJC Scopus subject areas

  • Pulmonary and Respiratory Medicine

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