The relationship between echocardiographic pulmonary steam velocity, respiratory functional tests and nocturnal oxygen desaturation in COPD patients

Abstract

The aim of the study is to investigate the relationships between nocturnal oxygen desaturation levels and echocardiographic findings to diagnose earlier the pulmonary arterial hypertension (PH) in chronic obstructive pulmonary disease (COPD) and without daytime hypoxemia. We studied 55 consecutive patients with COPD (62.67 ± 8.20 years, 5 females) admitting our outpatient clinic and having consented to participate. All patients underwent routine biochemical, hematologic, thyroid function tests and chest x-ray. Spirometric tests, carbonmomoxide diffusion capacities, nocturnal sleep oxygen saturation level measures and 6 minute walking tests were performed to all patients. Systolic pulmonary steam velocity with pulsed-waved doppler and pulmonary artery pressures (PAP) of the patients were measured by transthoracic echocardiography. Thirty of the patients were found to have a normal PAP and 25 of them were found to have a high levels. A significant difference was determined between two groups in the terms of Pa02 (p=0.030), DLCO (p=0.009), percent sleep time spent with SaO2 <90% (TST90), (p<0.0001), the thickness of right ventricle (p<0.0001), minimum Sa02 levels in sleep (p=0.0009), mean Sa02 levels (p<0.0001) and the frequencies of nocturnal desaturations (p=0.030). PH was detected more frequently (11/12,:92%) among COPD patients with longer TST90 levels than 20% of total sleep time. As a conclusion, PH is a common clinical entity particularly among the patients having more frequent and longer nocturnal desaturation episodes. Observations of nocturnal oxygen desaturation on COPD patients may be a diagnostic tool to anticipate PH and to influence survivals.