Oxygen therapy apnea with

Bi-level NIV may be used as a first-line treatment, with supplemental oxygen (27). Expiratory airway pressure is titrated to control h5q)opneas and apneas, and inspiratory airway pressure is added to control Paco2. If bi-level NIV fails, nasal volume ventilation may be used (29). In many patients with OHS and predominant OSA, once hypercapnia has improved (which may take several weeks) nCPAP may be used (29). Thirteen obese patients (n = 13) with a BMI > 35, aged 28-69 years with severe OSAS and hypercapnia (8.2 0.3 kPa) and failing to respond to initial CPAP therapy, were treated via a nasal nocturnal volume-cycled ventilator, which was tolerated by all patients. Significant improvements in daytime arterial blood gas levels were obtained after 7 to 18 days of nasal intermittent positive pressure ventilation (29) in 10 of the 13 patients three months later, 12 of the 13 patients could be converted to nCPAP therapy and one patient remained on NIV. In another study (37), the same results were observed after three months of home nocturnal bi-level NIV in seven patients, three of whom had severe obesity. 

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