Background: Obesity hypoventilation syndrome (OHS), previously termed Pickwickian Syndrome, is manifested by obesity, sleep-disordered breathing, and chronic daytime hypercapnia without other causes of hypoventilation. The vast majority of OHS population (ie, 90%) suffer from obstructive sleep apnea (OSA). Compared to non-OHS with similar obesity, OHS has been associated with more compromised pulmonary mechanics. We aimed to assess the potential impact of OHS on the nocturnal oxygen desaturation compared with BMI-matched OSA patients. Methods: This is a single center retrospective case control study. We evaluated data of 1,269 patients who had a level I polysomnography study at the Sleep Medicine and Research Center, King Abdulaziz University Hospital. OHS patients were diagnosed based on the presence of obesity (BMI ≥ 30 kg/m2), daytime hypercapnia (PaCO2 > 45 mm Hg) not explained by other causes. The exclusion criteria included the presence of other causes of hypercapnia and history of smoking. BMI-matched OSA patients were extracted and compared to the OHS patients. Microsoft Excel 365 was used to analyze the data. This study received approval from the Research Ethics Committee of the Faculty of Medicine, King Abdulaziz University (Reference No 580-22). Results: Of the 1,269 patients, 111 patients were included for analysis. Table 1 displays the main characteristics of the patients. Our analysis showed that OHS compared to OSA had statistically significant differences in the minimum and average nocturnal SpO2 as well as in SpO2 time below 90% (Figure 1). Conclusions: Compared to OSA, OHS patients had significantly worse nocturnal oxygen levels during sleep including the minimum average SpO2, and more prominently, the duration of sleep time with SpO2 below 90%. This phenomenon may increase the frequency and duration of deleterious arousals, thus leading to further fragmentation of sleep architecture.Table 1. The demographics of the patients included in the analysis (n= 111)Figure 1. The left panel illustrates the minimum and average SpO2 in OHS and OSA patients. The right panel shows the average sleep time in which SpO2 was less than 90 %.
Alahmadi et al. (Sun,) studied this question.