Obesity hypoventilation syndrome in bariatric surgery patients: an underestimated disease

Obesity is a known risk factor for obesity hypoventilation syndrome (OHS). However, study on the prevalence and clinical characteristics of OHS among bariatric surgery patients is scarce.To investigate the prevalence of OHS in bariatric surgery patients and to identify its related predictors.The study was conducted at a bariatric surgery center in a tertiary university hospital.A cross sectional analysis was performed in the patients undergoing bariatric surgery between March 2017 and January 2020. Anthropometric, laboratory, pulmonary function, blood gas analysis, and polysomnographic data was collected and analyzed.Of 522 patients, the overall prevalence of OHS was 15.1%, with men (22.8 %) having a greater frequency than women (9.4%) (P < .001). The prevalence increases with obesity severity, from 4.1% in those with body mass index (BMI) <35 kg/m2 to 39.1% in those with BMI ≥50 kg/m2. Of 404 patients with obstructive sleep apnea (OSA), OHS was present in 17.3%, with 9.8% in mild OSA, 10.0% in moderate OSA, and 27.3%in severe OSA. Only 11.4% of patients diagnosed with OHS had no OSA. On logistic regression, BMI (odds ratio [OR]: 1.10; 95% confidence interval [CI], 1.01-1.21; P = .033), neck circumference (OR: 1.15; 95% CI, 1.03-1.28; P = .014), serum bicarbonate (OR: 1.39; 95% CI, 1.20-1.61; P = .000), C-reactive protein (CRP) (OR: 1.04; 95% CI, 1.00-1.07; P = .034) were independently associated with OHS.In bariatric surgery patients, OHS presented a high prevalence, especially in men. Higher levels of BMI, neck circumference, serum bicarbonate, and CRP indicated higher risk of OHS.