Should the 6-Minute Walk Test Be Stopped If Oxyhemoglobin Saturation Falls Below 80%?

Objective: To examine the occurrence of adverse events in patients undergoing assessment for pulmonary rehabilitation when a 6-minute walk test (6MWT) continues despite desaturation below 80%. Design: Retrospective audit following REporting of studies Conducted using Observational Routinely-collected health Data (RECORD) Statement. Setting: Large teaching hospital. Participants: All patients (N=549) (55% men, mean age 69 +/- 11y) assessed for pulmonary rehabilitation (September 2005 to January 2016). Interventions: The standardized tests were conducted by experienced cardiorespiratory physiotherapists. Oxyhemoglobin saturation was monitored continuously using a pulse oximeter (lowest value used for analysis). Medical records were reviewed, and adverse events defined as tachycardia, bradycardia, chest pain, or other sign/symptom necessitating cessation. Main Outcome Measure: 6MWT. Results: Data from 672 walk tests were included with mean distance 369 (124) meters. The main diagnoses were chronic obstructive pulmonary disease (70%), interstitial lung disease (14%), and bronchiectasis (8%). Sixty individuals (11%) recorded desaturation below 80% without adverse events. Two adverse events were recorded during tests without desaturation; in 1 instance, chest pain with no evidence of cardiorespiratory compromise and in another, the patient stopped due to concern regarding blood sugar levels (11.5 mmol/L when tested). Independent predictors of desaturation to less than 80% were resting oxyhemoglobin saturation <95% (odds ratio [OR] 3.82, 95% confidence interval [CI] 2.06-7.08) and a diagnosis of interstitial lung disease or pulmonary arterial hypertension (OR 5.24, 95% CI 2.59-10.58). Conclusions: This study found that desaturation to less than 80% during a 6MWT was not associated with adverse events in a large cohort of patients referred to pulmonary rehabilitation and assessed by experienced physiotherapists, suggesting that test cessation due to desaturation in stable patients may be unwarranted. (C) 2018 by the American Congress of Rehabilitation Medicine