Evaluation and Management of Obesity Hypoventilation Syndrome. An Official American Thoracic Society Clinical Practice Guideline

Abstract

Background: The purpose of this guideline is to optimize evaluation and management of patients with obesity hypoventilation syndrome (OHS).Methods: A multidisciplinary panel identified and prioritized five clinical questions. The panel performed systematic reviews of available studies (up to July 2018) and followed the Grading of Recommendations, Assessment, Development, and Evaluation evidence-to-decision framework to develop recommendations. All panel members discussed and approved the recommendations.Recommendations: After considering the overall very low quality of the evidence, the panel made five conditional recommendations. We suggest that: 1) clinicians use a serum bicarbonate level <27 mmol/L to exclude the diagnosis of OHS in obese patients with sleep-disordered breathing when suspicion for OHS is not very high (<20%) but to measure arterial blood gases in patients strongly suspected of having OHS, 2) stable ambulatory patients with OHS receive positive airway pressure (PAP), 3) continuous positive airway pressure (CPAP) rather than noninvasive ventilation be offered as the first-line treatment to stable ambulatory patients with OHS and coexistent severe obstructive sleep apnea, 4) patients hospitalized with respiratory failure and suspected of having OHS be discharged with noninvasive ventilation until they undergo outpatient diagnostic procedures and PAP titration in the sleep laboratory (ideally within 2-3 mo), and 5) patients with OHS use weight-loss interventions that produce sustained weight loss of 25% to 30% of body weight to achieve resolution of OHS (which is more likely to be obtained with bariatric surgery).Conclusions: Clinicians may use these recommendations, on the basis of the best available evidence, to guide management and improve outcomes among patients with OHS.

Keywords: Pickwickian; bilevel PAP; chronic hypercapnic respiratory failure; hypercapnia; sleep-disordered breathing.

Figure 1.

Flowchart summarizing the panel’s recommendations. Obesity hypoventilation syndrome (OHS) may be suspected when symptoms lead to pulmonary or sleep consultation in stable conditions as an outpatient or during an episode of hospitalization due to acute-on-chronic hypercapnic respiratory failure. In the outpatient setting, the panel recommends performing a measurement of arterial blood gases (ABG) to confirm daytime hypercapnia for patients with high pretest probability of OHS (for example, very symptomatic patients with a body mass index [BMI] >40 kg/m²) or assess serum bicarbonate levels in cases in which there is a moderate or low pretest probability of OHS (for example, less symptomatic patients with a BMI of 30–40 kg/m²). When the bicarbonate level is ≥27 mmol/L, the panel recommends a confirmatory measurement of ABG to confirm the presence of hypercapnia and to carry out a sleep study to ascertain the presence and severity of sleep-disordered breathing. If the serum bicarbonate level is <27 mmol/L, OHS is highly unlikely. For management of hospitalized patients in acute-on-chronic respiratory failure treated with noninvasive ventilation (NIV) treatment, the panel recommends that patients be discharged on empiric NIV settings because of high risk of short-term (3 mo) mortality without therapy. The panel also recommends evaluation with a sleep study and positive airway pressure (PAP) titration in the sleep laboratory as early as possible after discharge from the hospital, ideally within 3 months of discharge. If the sleep evaluation demonstrates OHS and severe obstructive sleep apnea (OSA) (apnea–hypopnea index ≥ 30), the panel recommends continuous positive airway pressure (CPAP) titration and treatment. If, on the other hand, the sleep study demonstrates OHS with no OSA or mild to moderate OSA, the panel recommends NIV titration and treatment. In patients initially treated with CPAP who do not have adequate response to therapy (lack of symptom resolution or insufficient improvement in gas exchange during wakefulness or sleep), the panel recommends changing to NIV therapy. The panel also recommends that patients with OHS should be considered for bariatric surgery. All recommendations are conditional because of the very low level of certainty in the evidence. *In healthcare settings with limited or no access to NIV, discharging patients on auto-PAP would be preferable to no PAP, particularly given that 70% of patients with OHS have coexistent severe OSA. ^†It is important to note that OHS is a diagnosis of exclusion, and other causes of hypercapnia need to be investigated and excluded.