Treatment of OHS in Obesity (BMI ≥30 kg/m²) with Daytime Hypercapnia and No or Mild OSA
This protocol addresses obesity hypoventilation syndrome in the specific setting of obesity (body mass index ≥30 kg/m²) combined with daytime hypercapnia (arterial CO₂ tension ≥45 mmHg) and sleep-disordered breathing that does not meet criteria for severe obstructive sleep apnoea — an apnoea/hypopnoea index below 30 events per hour.
Clinical Scenario
OHS is defined by the coexistence of obesity (BMI ≥30 kg/m²), daytime hypercapnia (PaCO₂ ≥45 mmHg), and sleep-disordered breathing, after excluding other causes of alveolar hypoventilation. In this sub-population, obstructive sleep apnoea is absent or mild (AHI <30 events/h), indicating non-obstructive sleep hypoventilation as the predominant nocturnal disturbance.
Approach (Partial Overview)
For OHS patients with no or mild OSA, first-line management centres on a form of noninvasive ventilatory support delivered during sleep, integrated within a broader multimodality approach — the complete regimen, titration guidance, and further therapeutic options are available in the full structured protocol.
Treatment Targets
The primary clinical goals are a measurable reduction in daytime arterial CO₂ tension and an increase in arterial oxygen tension, reflecting correction of hypercapnia — reassessed at approximately 2 months after treatment initiation.
References
DOI: 10.1183/16000617.0097-2018
- Obesity hypoventilation syndrome (OHS) is defined as a combination of obesity (body mass index ⩾30 kg·m⁻²), daytime hypercapnia (arterial carbon dioxide tension ⩾45 mmHg) and sleep disordered breathing, after ruling out other disorders that may cause alveolar hypoventilation.
- The remaining patients have non-obstructive sleep hypoventilation with no or mild OSA.
- Noninvasive ventilation (NIV) should be considered as first-line therapy for OHS patients with no OSA or milder forms of OSA.
- Accordingly, for patients with more pure forms of hypoventilation and with fewer obstructive events during sleep (i.e. mild to no OSA), the treatment of choice would be NIV.
- Regardless of the chosen modality, PAP titration during sleep is strongly recommended.
- Therefore, a multimodality therapeutic approach is necessary to combine PAP therapy with strategies aimed at weight reduction and increased physical activity.
- Ventilatory support produces an improvement in gas exchange, which translates into a significant reduction in daytime wake PaCO₂ and an increase in arterial oxygen tension.
- Both PAP modalities seek to correct sleep hypoxaemia, obstructive events and hypercapnia.
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