Table 3 Long-term studies (>3 months) of positive airway pressure in OHS
AuthorNStudy typeInterventionDurationOutcomesComments
Masa7622Before/afterNIV and BPAP>4 monthsImproved symptoms; ↓ hospitalisations; improved ABGs
Berger5623Before/afterBPAP or CPAP7 years↓Paco2Therapy aimed at correcting specific sleep abnormality
de Lucas-Ramos5313Before/afterBPAP12 monthsImproved, Pao2, Paco2, FVC, ΔP0.1/ΔPaco2, ΔVE/ΔPaco2Likely recovery of chemoreceptor sensitivity to hypercapnia following BPAP
Perez de Llano6954RetrospectiveCPAP, BPAP and NIV7 years↑Pao2; ↓Paco2; ↓ dyspnoea, no weight changeOn review, substantial number on BPAP able to be switched to CPAP
Mokhlesi7375RetrospectiveBPAP and CPAPVariableChanges in Pao2 and Paco2 dependent on adherence rather than mode of therapy
Redolfi546Before/afterBPAP6–20 months↓Paco2; ↑leptin levels correlating positively with P0.1/Petco2 slope; ΔBMI by 2 kg/m2
Budweiser38126RetrospectiveBPAP10 years↓Nocturnal Paco2 by >23% and Hb compared with baseline associated with improved prognosis
Heinemann7535Before/afterBPAP12 and 24 monthsNormalisation of Paco2 and reduced base excess; ↓polycythemia; ↑ in VC and TLC; ↓RV/TLC

  • ABG, arterial blood gas; BMI, body mass index; BPAP, bilevel positive airway pressure; CPAP, continuous positive airway pressure; FVC, forced vital capacity; NIV, non-invasive ventilation; OHS, obesity hypoventilation syndrome; P0.1, occlusion pressure; Paco2, Pao2, arterial carbon dioxide and oxygen tensions; RV, residual volume; TLC, total lung capacity; VC, vital capacity; VE, minute ventilation.