Effectiveness of smoking cessation in smokers with COPD and nocturnal oxygen desaturation: Functional analysis.

Introduction: Chronic obstructive pulmonary disease (COPD) is the fourth cause of mortality and it's frequently associated with breathing sleep disorders.

Objective: The aim of the study is to point out the benefit of smoking cessation over three months in terms of improvement of respiratory functional variables.

Methods: A retrospective analysis was performed evaluating the impact of smoking cessation on 145 patients with COPD and nocturnal oxygen desaturation. For this purpose, for all patients, overnight pulse oxymetry detection on room air, arterial blood sampling, plethysmography and exhaled test for carbon monoxide were performed at baseline and 3 months after the beginning. Smoking cessation was achieved by varenicline plus individual counselling.

Results: About 51% of patients quit smoking which was established by exhaledcarbon monoxide (eCO) measure (cut-off 5 ppm). Patients who quit smoking displayed notably better results compared with patients who did not. The eCO significantly decreased by 16 ppm versus 4 (P = 0.01), oxygen desaturation index (ODI) was reduced by 3 points versus 0.8 (P = 0.01) and forced expiratory in 1 second volume increased by 7% of predicted value versus 1% (P = 0.01). The walking test was improved by 102 m versus 25 in sustainers (P = 0.01). The CAT score was also improved by 10 versus 8 in sustainers (P = 0.01) and PaO2 increased by 5 mm Hg versus 0.5 (P = 0.04). The percentage of SaO2 < 90% was improved by 6.7 versus 2.1 (P = 0.04).The logistic regression analysis displayed the possible influence of CAT (P = 0.02) and modified medical research council dyspnea test (P = 0.05) on ODI value.

Conclusions: Smoking cessation notably improves pulmonary functional parameters in quitters reporting nocturnal oxygen desaturation.