Predictive tools for nocturnal respiratory failure in patients with moderate and severe OSAS

Purpose: The impact of obstructive sleep apnea syndrome (OSAS) in terms of mortality, morbidity, and quality of life has been well established. Phenotyping OSAS is essential in order to make the best therapeutic choice. A particular subset of patients with OSAS shows nocturnal respiratory failure, defined by a nighttime oxygen saturation <90% in more than 30% of the total sleep time (TST90). The aim of this study was to identify possible predictive factors for nighttime respiratory failure (NRF) in patients with OSAS.

Methods: In this retrospective study, patients with suspected OSAS who underwent a sleep study were enrolled. Of 116 patients with moderate/severe OSAS who met the inclusion criteria, 67 also had nocturnal respiratory failure. We compared clinical, anthropometric, and laboratory data in patients with OSAS vs. OSAS and nocturnal respiratory failure.

Results: Patients with OSAS and nocturnal respiratory failure were more frequently female, had a higher BMI, lower daytime oxygen partial pressure (PaO2) in arterial blood, higher Apnea Hypopnea Index (AHI), and a lower number of sleep hours per night. Chronic obstructive pulmonary disease (COPD) was more diagnosed in the group of patients with nocturnal respiratory failure. A lower number of total sleep hours, lower daytime PaO2, lower AHI, increased oxygen desaturation index (ODI), and the presence of a diagnosed COPD were all found to increase the risk of having nocturnal respiratory failure.

Conclusion: COPD, AHI, ODI, daytime PaO2, and total sleep hours are the main predictors for NRF in patients with moderate and severe OSAS.