Obesity BMI ≥30 kg/m² Obesity Hypoventilation Syndrome in this context involves a patient with obesity (BMI ≥30 kg/m²), daytime hypercapnia (arterial CO₂ ≥45 mmHg), and sleep-disordered breathing. The defining feature of this phenotype is concomitant severe obstructive sleep apnoea (apnoea/hypopnoea index ≥30 events/h) — a presentation shared by nearly 70% of OHS patients and the critical factor that determines which treatment modality is chosen first.
For this OHS phenotype, first-line management centres on a specific positive airway pressure modality delivered as part of a structured multimodality therapeutic strategy — the complete regimen, titration requirements, and criteria for further interventions in eligible patients are detailed in the full protocol.
The primary target is correction of daytime hypercapnia (arterial CO₂ <45 mmHg), with adequate clinical and arterial blood gas control assessed over the first 2–3 months of therapy.
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.
CPAP is considered the first-line treatment modality for OHS phenotype with concomitant severe obstructive sleep apnoea, whereas NIV is preferred in the minority of OHS patients with hypoventilation during sleep with no or milder forms of obstructive sleep apnoea (approximately <30% of OHS patients).
Nearly 70% of patients have concomitant severe OSA (AHI ⩾30 events·h⁻¹).
Continuous positive airway pressure (CPAP) could be first-line treatment for OHS patients with concomitant severe obstructive sleep apnoea (OSA).
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.
Bariatric surgery is a cost-effective strategy for managing severe obesity with comorbidity such as OSA with long-term efficacy data.
Both PAP modalities seek to correct sleep hypoxaemia, obstructive events and hypercapnia.
However, we encourage clinicians to monitor these patients closely for the first 2–3 months after initiating PAP therapy.
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