Obesity Hypoventilation Syndrome (OHS) Management
Diagnosis and Initial Treatment
- For stable ambulatory patients diagnosed with OHS and concomitant severe OSA (AHI > 30 events/h), CPAP therapy should be initiated as first-line treatment rather than NIV, according to the American Thoracic Society 1
- A sleep study is necessary to assess for sleep-disordered breathing and OSA severity, as recommended by the American Thoracic Society 1
- Screening approach for OHS includes checking serum bicarbonate level in obese patients with OSA, and if bicarbonate >27 mmol/L, performing arterial blood gas analysis, as suggested by the American Thoracic Society 1
Treatment of Severe OSA
- With severe OSA (AHI >30 events/h), CPAP therapy should be started, and response should be monitored over 6-8 weeks, as recommended by the American Thoracic Society 1
- If hypercapnia persists despite adequate CPAP adherence, switch to NIV, according to the American Thoracic Society 1
Treatment of Respiratory Failure
- For patients with respiratory failure suspected of having OHS, NIV therapy should be started before hospital discharge, as recommended by the American Thoracic Society 1
- High IPAP (>30 cmH₂O) and EPAP (>8 cmH₂O) settings are commonly required, as reported in Thorax 2
- Consider placement in HDU/ICU for NIV, as the risk of NIV failure is greater and intubation may be more difficult, according to Thorax 2
Non-Invasive Ventilation (NIV) Settings
- Initial NIV settings: IPAP >30 cmH₂O and EPAP >8 cmH₂O are commonly required, as reported in Thorax 2
- Volume control (or volume assured) modes may be more effective when high inflation pressures are required, according to Thorax 2
Weight Loss Interventions
- Target sustained weight loss of 25-30% of actual body weight to achieve resolution of hypoventilation, as recommended by the American Thoracic Society 1
- Bariatric surgery is the most effective method for achieving this degree of weight loss, although this fact is from Praxis Medical Insights, a similar recommendation can be found in other sources 1
Fluid Management
- Fluid overload commonly contributes to ventilatory failure in OHS and is easily underestimated, as reported in Thorax 2
- Consider forced diuresis, according to Thorax 2
- In patients with known left ventricular dysfunction, consider a BNP-directed fluid management strategy, as suggested in Thorax 2