Staging of obesity-associated hypoventilation in patients with morbid obesity scheduled for bariatric surgery.

Background: Almost 20% of Polish citizens aged >15 years are obese and this number is increasing. Numerous obesity-associated diseases include, quite notably, also sleep-related breathing disorders and hypoventilation. This study aimed to analyse the prevalence of obesity hypoventilation syndrome (OHS) and hypoventilation staging in a group of patients qualified for bariatric surgery within the Comprehensive Specialist Care in Bariatrics (KOS-BAR) pilot program designed and running in Poland since 2021. Methods: Prior to the bariatric procedure, the participants were referred to a pulmonologist for assessment. We retrospectively analysed the records of 134 patients. Results: Almost all of the tested bariatric patients (n = 122, 91.0%) had obstructive sleep apnea mainly classified as severe (59.0%). Hypoventilation was confirmed in 30 patients (22.4%), and in 37.9% of them, increased levels of serum bicarbonate were found. Chronic diurnal hypercapnia was confirmed in 7.9% of patients (10/122). Conclusions: Hypoventilation as well as obstructive sleep apnea in the obese population is a significant issue. The presented study group included patients in stages 0-IV of obesity-associated hypoventilation. The conducted analysis suggests that the most common form of hypoventilation among patients qualified for bariatric surgery is obesity-associated sleep hypoventilation (stage I).