Nocturnal hypoxia in patients with idiopathic pulmonary arterial hypertension

Lu Yan; Qin Luo; Zhihui Zhao; Qing Zhao; Qi Jin; Yi Zhang; Zhihong Liu

doi:10.1177/2045894019885364

Nocturnal hypoxia in patients with idiopathic pulmonary arterial hypertension

Pulm Circ. 2020 Aug 21;10(3):2045894019885364. doi: 10.1177/2045894019885364. eCollection 2020 Jul-Sep.

Authors

Lu Yan¹, Qin Luo¹, Zhihui Zhao¹, Qing Zhao¹, Qi Jin¹, Yi Zhang¹, Zhihong Liu¹

Affiliation

¹ Center for Pulmonary Vascular Diseases, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China.

Abstract

Background: Sleep-disordered breathing causes a variety of cardiovascular complications and increases the risk of a poor prognosis in patients. There is still some controversy regarding the clinical diagnosis and treatment of sleep-disordered breathing in patients with pulmonary hypertension. The aim of this study was to determine the incidence of desaturation in idiopathic pulmonary arterial hypertension (IPAH) patients, evaluate the effect of desaturation on the clinical status of patients with IPAH, and identify possible influencing factors.

Methods: Patients with IPAH diagnosed by right heart catheterization who underwent overnight cardiorespiratory monitoring from January 2018 to July 2019 were enrolled. Nocturnal hypoxic time was defined as the time that oxygen saturation remained below 90%. Desaturation was defined as a nocturnal oxygen saturation level less than 90% for more than 10% of the total recording time. Baseline clinical characteristics and parameters were collected to compare IPAH patients with and without desaturation. In addition, logistic regression was performed to identify possible factors associated with desaturation in IPAH patients.

Results: Fifty patients with IPAH were included. Among them, 17 patients presented desaturation. Patients with desaturation were older, had a shorter six-min walking distance (6MWD), had a higher mean right atrial pressure, and had a lower daytime arterial oxygen partial pressure than patients without desaturation, and there were significant differences in the VE/VCO₂ and VE/VCO₂ slope (P < 0.05). The multivariate logistic regression analysis indicated that the 6 MWD (OR = 0.971, 95% CI: 0.948-0.994, P = 0.013) and; VE/VCO₂ slope (OR = 1.095, 95% CI: 1.010-1.307, P = 0.032) were independently associated with desaturation after adjusting for age, sex, and body mass index.

Conclusion: Nocturnal hypoxia is common in IPAH patients. Desaturation may aggravate the clinical situation of patients with IPAH. In IPAH patients, a poor exercise capacity (6 MWD) and the VE/VCO₂ slope can predict desaturation after adjusting for age, sex, and body mass index.

Keywords: desaturation; idiopathic pulmonary arterial hypertension; nocturnal hypoxia.