Walking test for assessing lung function and exercise performance in patients with cardiopulmonary disease

Background: Dyspnea is common among patients with cardiopulmonary disease, and 'daily disability' is defined as a functional impairment resulting from exercise intolerance. The maximal oxygen uptake (VO2max) during exhausting work is not only the best single physical indicator of the capacity of a man for sustaining hard muscular work, but also the most objective method by which one can determine the physical fitness of an individual as reflected by his cardiovascular system. However, the expense, time and personnel requirements make this procedure prohibitive for testing large group. The walking test is well-known type of exercise and it cost nothing to perform and have good reproducibility. Thus we performed the walking test and investigated correlations with spirometry, ABG and exercise test. Method: We observed the walking test and exercise test by cycle ergometer in 37 patients who visited our hospital because of dyspnea. Arterial blood gas analysis and spirometry, dyspnea index were performed, too. Result: (1) The VO2max was significantly lower in patients with COPD and cardiovascular disease than asthma and dyspnea on exertion group (p < 0.05). The walking test distance was also lower in former. (2) The 12 minute walking test was significantly correlated with VO2max, PaCO2, FVC (%), FEV1 (%) in all patients (p < 0.05), and the walking test was only correlated with VO2max in patients with COPD (p < 0.05). (3) In COPD patients, the VO2max was best correlated with FEV1 (%) and FVC (%) and significantly correlated with walking test. But there was no correlation between walking test and FEV1 (%) and FVC (%). (4) The 6 minute walking test was well correlated with 12 minute walking test (r = 0.92, p < 0.01). Conclusion: The walking test is the simple method for assessing exercise performance in patient with cardiopulmonary disease and a reliable indicator for VO2max. And the walking test is practical method for assessing on everyday disability rather than maximal exercise capacity. The 6 minute walking test is highly correlated with 12 minute walking test and a less exhausting for the patients and a time-saving for the investigator.