Predictors of Nocturnal Oxygen Desaturation in Normoxemic Patients with Moderate to Very Severe Chronic Obstructive Pulmonary Disease.

Abstract

Introduction: COPD is associated with complications such as reduced oxygen saturation and hypoventilation during sleep and is underdiagnosed among normoxemic patients. To identify the daytime parameters to predict nocturnal oxygen desaturation in normoxemic patients with moderate to very severe chronic obstructive pulmonary disease. To correlate the presence of nocturnal oxygen desaturation with pulmonary hypertension. Material and methods: A cross-sectional study was performed at ACS medical college Chennai for 14 months from May 2017 to June 2018. The study population included 103 participants. Data on variables such as 6-minute walk test, spirometry, nocturnal oximetry, partial pressures of O2 and CO2 were assessed. Results: A total of 103 patients were included in the analysis with 93.2% males and 3.9% current smokers and 87.4% ex-smokers. 52.4% had a normal chest X-ray. Around 45.6% had hyperinflated lungs. In the 6 minutes-walktest, 32% participants had desaturation. 50.5% had positive C-reactive protein levels indicating the presence of systemic inflammation. Right atrial/right ventricular dilatation was noted among 34% participants. Nocturnal desaturation with 3 to 4 episodes/hour was present among 39% participants. Univariate analysis results show that post FEV 1, partial pressure of oxygen and carbon dioxide, presence of desaturation and RA/RV dilatation on echocardiography were all statistically significant predictors of nocturnal oxygen desaturation in normoxemic patients with moderate to very severe Chronic Obstructive Lung Disease. Conclusion: Screening the COPD patients for these daytime predictors will enable in identifying the patients who have nocturnal desaturation. This in turn will aid in early initiation of home oxygen therapy.