Results from a 6-minute walk test (6MWT) with continuous monitoring of blood oxygen saturation SpO2 showed that certain people with respiratory disorders may have values throughout the test that are lower than the SpO2 obtained at the end of the test. However, whether or not this method enhances the yield of walk-induced desaturation detection in predicting death and hospitalizations in people with COPD is still unknown. About 51% of the individuals were male, and all of them, 420 in total, had some degree of COPD (moderate to extremely severe) and had to take the 6-minute walk test while their oxygen saturation was monitored continuously. If the blood oxygen saturation drops by more than or equal to 4% points during the exercise, a person is said to be desaturated. Hospitalization rates and all-cause death were evaluated 1 year after the 6MWT. After a median (interquartile range) of 55.5 (30.264.1) months, 149 individuals (35.4% of the total) died. Around 299 out of 421 samples (71%) showed signs of desaturation. The average blood oxygen saturation during the test was higher than the final blood oxygen saturation (88 [82–92]% vs. 90 [84–93]%) (P<.001). In 81/421 (19.2%) subjects, desaturation was observed during (but not after) the test. Desaturation either at the end of the test (1.85 [95% CI 1.023.36]) or only along the test (2.08 [95% CI 1.094.01]) remained significant predictors of mortality after adjustment for sex, body composition, FEV1, residual volume/total lung capacity ratio, walking distance, O2 supplementation during the test, and comorbidities. Patients presenting with any form of desaturation were more likely to require hospitalization than those without exercise desaturation. According to logistic regression analysis, the solely observed desaturation was predicted by walking interruption and lung CO diffusing capacity. Independent associations between O2 desaturation during exercise and all-cause mortality and hospitalizations in COPD patients were found when measurements were taken at intervals during the test rather than at the end.
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