From the Guidelines
Obesity hypoventilation syndrome (OHS) should be treated with positive airway pressure therapy, with continuous positive airway pressure (CPAP) being first-line for most patients, as recommended by the American Thoracic Society clinical practice guideline 1. The treatment of OHS involves a combination of positive airway pressure therapy, weight loss, and supplemental oxygen therapy.
Key Components of Treatment
- Positive airway pressure therapy: CPAP is typically started at 8-12 cmH2O and titrated based on response, with bilevel positive airway pressure (BiPAP) considered for patients with persistent hypercapnia despite CPAP 1.
- Weight loss: a goal of 10% reduction in body weight through dietary changes and increased physical activity is recommended, with bariatric surgery considered for those with BMI >40 kg/m² or >35 kg/m² with comorbidities 1.
- Supplemental oxygen therapy: may be needed if hypoxemia persists despite positive airway pressure.
Diagnosis and Management
The diagnosis of OHS requires a sleep study (polysomnography or respiratory polygraphy) to establish the presence of sleep-disordered breathing (SDB) and a measurement of arterial blood gases during wakefulness to establish the presence of hypercapnia 1.
Important Considerations
- OHS is a serious breathing disorder that can lead to respiratory acidosis, pulmonary hypertension, and right heart failure if left untreated 1.
- The underlying pathophysiology involves a combination of increased mechanical load on the respiratory system from excess weight, altered respiratory drive, and often coexisting obstructive sleep apnea, creating a vicious cycle of worsening respiratory function 1.
From the Research
Definition and Mechanisms of Obesity Hypoventilation Syndrome
- Obesity hypoventilation syndrome (OHS) is a sleep disorder characterized by insufficient sleep-related ventilation, resulting in abnormally elevated arterial carbon dioxide pressure (PaCO2) during sleep and demonstration of daytime hypoventilation 2.
- The primary mechanisms that can generate diurnal hypoventilation in obese patients include alteration of the respiratory mechanics secondary to obesity, central hypoventilation secondary to leptin resistance, and sleep disorder with sleep hypoventilation and obstructive apnoeas 2.
Treatment of Obesity Hypoventilation Syndrome
- Non-invasive ventilation (NIV) is an effective form of treatment in patients with OHS who have concomitant severe obstructive sleep apnoea (OSA) 3.
- NIV has been shown to be more effective than lifestyle modification in improving daytime PaCO2, sleepiness, and polysomnographic parameters in patients with OHS without severe OSA 3.
- The use of continuous positive airway pressure (CPAP) as initial treatment of OHS has been recommended, especially in patients with coexistent severe OSA, due to its similar effectiveness to NIV but lower cost and resource requirements 4.
Comparison of Different Positive Airway Pressure Interventions
- A network meta-analysis compared different positive airway pressure interventions, including CPAP, bi-level PAP with back-up rate (BPAP-BUR), BPAP without BUR, and hybrid devices that target a pre-set volume by adjustment of pressure support (VT-PS) 5.
- The results suggested superiority of VT-PS and BPAP over other PAP interventions for daytime hypercapnia and subjective daytime somnolence 5.
- A systematic review and meta-analysis found that PAP therapy was associated with increased resolution of OHS and improvements in mortality, gas exchange, daytime sleepiness, sleep quality, quality of life, and emergency department visits 6.