Factors predicting exercise-induced oxygen desaturation in stable COPD

Abstract

Background: Exercise induced oxygen desaturation (EID) is highly prevalent among patients with COPD. We suggested that, some resting pulmonary functions and blood gas parameters might be used as screening test to predict exercise-induced oxygen desaturation in COPD. Objective: The aim of this work was to evaluate different parameters that might predict (EID) in COPD patients. Design: Randomized, double blind, prospective study. Methods: This study included 55 patients with stable COPD, resting pulmonary functions; arterial blood gases, echocardiography, and incremental cardiopulmonary exercise testing were done for all patients. We considered the patient to be desaturated if O2 saturation decreased ⩾4 mmHg with exercise. We compared desaturated (DS) and nondesaturated (NDS) patients. Results: Oxygen desaturation was found in 28 subjects after CPET, while 27 subjects were nondesaturated (NDS). FEV1% was significantly lower in DS (P = 0.001), DLCO was significantly lower in DS (P = 0.001), and resting oxygen saturation (base-line) was significantly lower in DS (P = 0.000). Resting PaCO2 was significantly higher in DS (P = 0.000), pulmonary artery systolic pressure PAP was significantly higher in DS (P = 0.016), and mMRC score was significantly higher in DS (P = 0.000), while there were no statistically significant differences of age, FEV1/FVC, (TLC), and (RV). On performing regression analysis the most sensitive predictor for EID was base line SaO2 (resting SaO2). Conclusion: Although multiple factors can predict EID in stable COPD (FEV1%, DLCO, resting SaO2, PaCO2, mMRC score, and PAP), base line SaO2 is the most sensitive factor.

Keywords

• COPD
• Exercise
• Desaturation
• Base-line SaO2