Value of preoperative 6-minute walk test for predicting postoperative pulmonary complications

Abstract

OBJECTIVES: The objective of this study was to determine the performance of preoperative 6-minute walk test (6MWT) for predicting postoperative pulmonary complications (PPC) in high risk patients undergoing elective surgery under general anesthesia. METHODS: A prospective cohort study was conducted in patients scheduled to undergo elective thoracic or nonthoracic surgery and indicated for preoperative pulmonary evaluation in Songklanagarind Hospital, Songkhla, Thailand. Preoperative spirometry, 6MWT were done and 30-day PPC were recorded. The multiple regression analysis and receiver operating characteristic (ROC) curves were used to analyze the variables and to compare the performance of 6MWT and spirometry tests. RESULTS: A total of 78 participants were recruited into the study. 6MWT was done completely in all cases without any complications. Among these tests, 14 cases (17.9%) had contraindications to spirometry and two cases were unable to achieve the criteria for acceptable efforts. PPC developed in 17 cases (21%) with a high mortality (17.7%). A multiple regression analysis showed elderly, poor general health status, smoking history, low level of the mean value of forced expiratory volume in 1 second (FEV1) % predicted (by spirometry) and shorter 6-minute walk distance (6MWD) were the independent factors associated with PPC. Patients developing PPC had a significantly lower preoperative 6MWD compared with patients without PPC (256.0 ± 48.0 versus 440.0 ± 117.1 meters, p < 0.001). 6MWD of ⩽325 meters was a threshold for predicting PPC with 77% sensitivity and 100% specificity, and had a good predictive value for PPC similar to that for the FEV1 %. CONCLUSIONS: Preoperative 6MWT is a very useful alternative test for predicting PPC in high risk patients scheduled to undergo surgery under GA.