The following is the summary of “Continuous Monitoring of Pulse Oximetry During the 6-Minute Walk Test Improves Clinical Outcomes Prediction in COPD” published in the January 2023 issue of Respiratory Care  by Batista, et al.

It was discovered by continuously measuring S^pO2 during the 6 minute walk test (6MWT) that some patients with respiratory disorders may display values throughout the test lower than S^pO2  reported at the end of the test. It is not yet known if this method enhances the accuracy of walk-induced desaturation detection in making prognoses of death and hospitalizations in COPD patients.421 patients (51% male) with mild-to-severe COPD did a 6MWT while their S^pO2 was continuously monitored. Having a decrease in S^pO2 ≥4% during exercise was considered desaturation. The rate of hospitalizations in the year following the 6MWT and the risk of death from any cause were measured.

In the middle of a mean (IQR) follow-up of 55.5 (30.264.1) months, 149 individuals (35.4% of the total) passed away. About 299 out of 421 samples (71%) showed signs of desaturation. End S^pO2 was lower than average SpO2 during the test (88 [8,292]% vs. 90 [8,493]%) (P< .001). 81  out of 421 (19.2%) participants showed signs of desaturation during (but not after) the test. The presence of desaturation at the end of the test (1.85 [95% CI 1.02–3.36]) or only along the test (2.08 [95% CI 1.09–4.01]) remained significant predictors of mortality after adjusting for sex, body composition, FEV¹, residual volume/total lung capacity ratio, walk distance, O² supplementation during the test, and comorbidities in a multivariate Cox regression model. 

There was a correlation between presenting with any desaturation and a greater hospitalization rate than those who presented without exercise desaturation. Using logistic regression, researchers identified 2 independent predictors of desaturation during the test: walking interruption and diffusing capacity of the lung for carbon monoxide.  In adults with COPD, O² desaturation was independently related to all-cause mortality and hospitalizations, despite being overlooked by end-exercise S^pO2.

Source: rc.rcjournal.com/content/68/1/92