What is the treatment for Obesity Hypoventilation Syndrome (OHS)?

Treatment of Obesity Hypoventilation Syndrome (OHS)

The treatment of Obesity Hypoventilation Syndrome should include positive airway pressure (PAP) therapy as the cornerstone of management, with CPAP as first-line treatment for patients with concomitant severe OSA, and weight loss interventions targeting 25-30% reduction in body weight, preferably through bariatric surgery when appropriate. 1

Diagnosis and Initial Assessment

• OHS is defined by the combination of obesity (BMI ≥30 kg/m²), sleep-disordered breathing, and awake daytime hypercapnia (PaCO₂ >45 mmHg at sea level), after excluding other causes of hypoventilation 2
• A serum bicarbonate level <27 mmol/L can be used to exclude OHS in obese patients with sleep-disordered breathing when clinical suspicion is low (<20%) 1
• Arterial blood gas analysis should be performed in patients with high clinical suspicion for OHS 1, 3

Treatment Algorithm

For Stable Ambulatory Patients:

• First-line therapy based on OSA severity:

  • For OHS with severe OSA (AHI >30 events/hour): Use CPAP as first-line treatment 1, 2
  • For OHS with no OSA or mild-to-moderate OSA: Use noninvasive ventilation (NIV) 2, 3

• Monitoring response to therapy:

  • If patients on CPAP show inadequate response (persistent symptoms or insufficient improvement in gas exchange), switch to NIV 1, 3

For Hospitalized Patients with Respiratory Failure:

• Patients hospitalized with respiratory failure suspected of having OHS should be discharged with NIV 1
• These patients should undergo outpatient diagnostic procedures and PAP titration in a sleep laboratory within 2-3 months after discharge 1, 2
• In settings with limited or no access to NIV, discharging patients on auto-PAP is preferable to no PAP therapy 1

Weight Management

• All patients with OHS should be advised to pursue weight-loss interventions targeting 25-30% reduction in body weight 1
• Bariatric surgery should be considered for eligible patients, as it is more likely to result in greater and more sustained weight loss than lifestyle interventions alone 1, 2
• The degree of weight loss necessary to mitigate cardiovascular and metabolic risks in OHS is not precisely known, but substantial weight loss can lead to resolution of OHS 1, 4

PAP Titration Guidelines

• For NIV titration:
  • Minimum starting IPAP and EPAP should be 8 cm H₂O and 4 cm H₂O, respectively 3
  • Maximum IPAP should be 30 cm H₂O for adult patients 3
  • Pressure support should be increased if tidal volume is low (<6-8 mL/kg) or if arterial PCO₂ remains elevated 3

Management of Comorbidities

• OHS is associated with significant cardiovascular and metabolic comorbidities including heart failure, coronary disease, and pulmonary hypertension 5, 4
• Appropriate management of these comorbidities is essential for improving prognosis 5, 4

Common Pitfalls to Avoid

• Do not use supplemental oxygen alone to treat sleep-related hypoventilation, as this may worsen hypercapnia 3
• Avoid discharging hospitalized patients without arranging prompt outpatient sleep study and PAP titration 2
• Do not confuse OHS with other conditions associated with hypoventilation, particularly COPD, as misdiagnosis can lead to inappropriate treatment 6

Follow-up and Monitoring

• Schedule periodic reassessment appropriate to disease severity 3
• Follow-up visits should include monitoring for persistent daytime hypoventilation 3
• Treatment efficacy should be assessed through clinical symptoms, gas exchange parameters, and sleep quality 5, 7