Prevalence and characteristics of non-hypoxemic COPD patients exhibited exercise-induced desaturation during 6MWT

Introduction: Exercise-induced desaturation (EID) is associated with impaired daily physical activity and increased mortality in COPD. The clinical characteristics of FEV 1 , DLCO and SpO 2 have been suggested as good predictors of EID. However, a combination of criteria that could improve accuracy in detecting EID, needs investigation. Aim: To study the prevalence and characteristics of COPD patients who desaturate (nadir-SpO 2 ≤88%) in walking. Method: 402 non-hypoxemic COPD patients (age:64±8yrs; BMI:26±6kg/m2; FEV 1 :52±19%pred; DLCO:54±20%pred) performed 6MWT while oxygen saturation was recorded by pulse oximeter. Using ROC curves, the threshold values with the best specificity and sensitivity to predict oxygen desaturation were determined for age, BMI, FEV 1 , FRC, DLCO, PaO 2 , PaCO 2 , and baseline SpO 2 . Subsequently, univariate and multivariate logistical regression were performed. Results: Univariate analysis revealed that patients aged≥60yrs; an overweight or obese BMI; a FEV 1 135%pred; a DLCO 2 2 2 1 , DLCO, PaO 2 , SpO 2 and gender remained significant in multivariate logistical regression. Conclusion: A combination of clinical characteristics (DLCO 1 2 2