Oxygen consumption, shuttle walking test and the evaluation of lung resection

Assessment of peak oxygen uptake (VO(2)) is recommended in the evaluation of patients with borderline pulmonary function as VO(2) is the strongest independent predictor of postoperative pulmonary complications. However, the measurement of VO(2) requires expensive equipment not available in many medical facilities. The shuttle walking test (SWT) has been proposed to be used as a screening tool prior to performing a cardiopulmonary exercise test. Although an association exists between SWT distance and VO(2), only one small study directly measured VO(2) during the SWT.

The aim of this study was to further validate the VO(2)-SWT association by directly measuring VO(2) during SWT in a larger cohort of patients with stable chronic obstructive pulmonary disease (COPD).

Fifty stable COPD patients with mild/severe disease were studied. Each patient performed an SWT while wearing a validated portable metabolic monitor.

Mean VO(2) (ml/kg/min) measured after each finalized minute of the SWT was (95% confidence interval): 6 (5-7), 9 (8-10), 11 (10-12), 13 (11-14), 15 (14-16), 18 (16-20) and 21 (18-26) for minutes 1-7, respectively. Patients that completed the British Thoracic Society-recommended 25 shuttles (5 min or 250 m) in the SWT had a mean VO(2) of 15 (14-16). The positive predictive value for walking 25 shuttles (predicting a VO(2) of >or=15ml/kg/min) was 90% and the negative predictive value was 90%.

Our findings validate the association between VO(2) and SWT distance and facilitate the interpretation of the test in general practice, particularly when deciding the candidacy of a patient for surgical resection.