Guideline sources The following summarized guidelines for the evaluation and management of obesity hypoventilation syndrome (OHS) are prepared by our editorial team based on guidelines from the American Thoracic Society (ATS 2019). 1 Guidelines 1. Diagnostic investigations Blood gas analysis: consider measuring arterial partial pressure of CO rather than serum bicarbonate or SpO for the diagnosis of OHS in patients with obesity and sleep-disordered breathing with a high pretest probability of having OHS. C Show 2 more 2. Respiratory support Positive airway pressure therapy: Consider initiating positive airway pressure therapy during sleep in stable ambulatory patients with OHS. C Consider initiating CPAP therapy rather than noninvasive ventilation as first-line therapy in stable ambulatory patients with OHS and concomitant severe obstructive sleep apnea (apnea- https://web.pathway.md/diseases/rec9GAFc0YAdEBiNW 1/2 6/30/23, 1:22 AM Obesity hypoventilation syndrome Pathway hypopnea index 30 events/hour). C Noninvasive ventilation: consider initiating noninvasive ventilation before hospital discharge in hospitalized patients with respiratory failure suspected of having OHS, until they undergo outpatient workup and titration of positive airway pressure therapy in the sleep laboratory, ideally within the first 3 months after hospital discharge. C 3. Nonpharmacologic interventions Weight loss: consider offering weight loss interventions producing sustained weight loss of 25- 30% of actual body weight to achieve resolution of hypoventilation in patients with OHS. C Clinical findings Symptoms Past medical history Excessive daytime sleepiness HF Frequent nighttime awakenings Obesity Headache Obstructive sleep apnea Restless sleep Vascular exam Sleeping disorder Snoring Peripheral edema Vital signs Lab findings O2 saturation arterial partial pressure of CO2 Cardiac exam serum bicarbonate PaO2 Jugular venous distention References 1. Babak Mokhlesi, Juan Fernando Masa, Jan L Brozek et al. Evaluation and Management of Obesity Hypoventilation Syndrome. An Official American Thoracic Society Clinical Practice Guideline. Am J Respir Crit Care Med. 2019 Aug 1;200 3):e6-e24. Open https://web.pathway.md/diseases/rec9GAFc0YAdEBiNW 2/2