PURPOSE: To validate the 6minute walk test (6MWT) as a complement to spirometry. To determine the 6MWT reliability in assessing maximum aerobic capacity (MAC), comparing it with the VO2max measured by the cardiopulmonary exercise test (CPET).
METHODS: Retrospective, observational study. 77 consecutive patients were studied with static pulmonary function tests (FEV1, FVC and FEV1/FVC ratio), 6MWT and CPET(cycle ergometer). Statistics: Linear regression. ANOVA of a factor.
RESULTS: Median Age: 62 years (26-82); 80.5% men and 19,5% women. BMI: 26,9±3,9 Kg/m2, FEV1: 2,5±0,8 L, 81±23% predicted, FVC: 3,7±1,0 L, 96±21% predicted, FEV1/FVC ratio: 0,67 + 0,13 (0,28-0,91), DLCO: 21,6±6,4 ml/min/mmHg, 78± 22% predicted, PaCO2: 38,5±5 mmHg, PaO2: 78,2±12,5 mmHg. VO2max: 17,1±5,1 ml/Kg/min. Work reached : 104±33 Watts, 67± 18% predicted. Anaerobic threshold: 0,93±0,30 L/min, 43±12% of VO2max. Maximum heart rate: 139±23 beats/min, cardiac reserve: 13±12%, oxygen pulse: 9,5±2,7 ml/min, maximum ventilation: 60,5±17,7 L/min, respiratory reserve: 30± 15%. Maximum distance reached on the 6MWT (6MWD): 464±93 meters. Using the Cahalin formula [VO2max = 0.006 × 6MWD(feet) + 3.38], there was an index of correlation between the 6MWT and the measured VO2max of r = 0.73 and R2 = 0.532 (p < 0.001). Comparing the two tests considering the intervals of normal-mild compromised VO2max (>20 ml/kg/min), moderate-severe (< 15 ml/kg/min) and intermediate (16-20 ml/kg/min), there is correlation with 6MWD for these patients, with F of 31 and p < 0,001. There was a statistically significant difference in the VO2max between the groups and within the groups.
CONCLUSION: With a 95% of reliability, it would be possible to affirm that, in the low and high levels of VO2max, there is better correlation with the 6MWD, because there is no intersection between the smaller and greater ranks (p < 0.001).
CLINICAL IMPLICATIONS: Patients with 6MWD < 365m could be assumed to have a VO2max < 15 mL/kg/min (moderate to severe compromise of MAC) and those with 6MWD > 546m could be assumed to have a VO2max > 20 mL/kg/min (none to mild compromise of MAC).
DISCLOSURE: Luis Giraldo, None.