Nocturnal hypoxemia

Bedard MA, Montplaisir J, Richer F, Malo J. Nocturnal hypoxemia as a determinant of vigilance impairment in sleep apnea syndrome. Chest 1991 100 367-370. 

Of six patients with central sleep apnea, who were receiving opioids (morphine equivalent doses of 120 20 mg/day) for chronic pain, four achieved symptomatic improvement when treated with bi-level ventilation, correcting nocturnal hypoxemia and reducing sleep fragmentation P ]. 

Nocturnal hypoventilation, which persists during the day in obese patients with nocturnal apneas and hypoventilation may be associated with COPD, defining the overlap syndrome (3). In 264 OSAS patients (32), 30 had coexistent COPD, with hypoxemia in 57%, hypercapnia in 27%, and PH in 37% of them. In the other 234 pure OSAS patients, only 26% were hypoxic, 8.5% were hypercapnic, and 11 % had PH at baseline. The same schedule may be proposed for OHS, but long-term studies are also warranted to confirm the initial choice and continuation of nCPAP or bi-level NIV. 

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