A 52-year-old woman (height, 160 cm; weight, 127 kg; BMI, 51; and neck circumference, 45 cm) presented with a 6-year history of chronic fatigue, involuntarily falling asleep during the day, loud snoring, and witnessed apneas. Previous diagnoses included chronic fatigue syndrome, hypertension, depression, hypothyroidism, and noninsulin-dependent diabetes. Medications included glyburide, furosemide, potassium chloride, buspirone, and fluoxetine. Previous polysomnography (September 1995) using a split-night protocol had confirmed the presence of hypoxemia, and frequent obstructive apneas were corrected with nasal CPAP of 10 cm H2O. Beginning in March 2000, she was treated with gabapentin; time-release morphine sulfate, 45 mg bid; and hydrocodone, 7.5 mg, as needed for diabetic neuropathy and Charcot foot disease. The morphine sulfate was increased to 40 mg tid in June 2000 and was subsequently changed to methadone, 10 mg bid, in October 2000. Except for obesity and Charcot foot disease, general and neurologic examinations including cranial MRI were normal. Because of increasingly profound hypersomnia in spite of nightly use of nasal CPAP, polysomnography was repeated in February 2001 beginning with her previous therapeutic pressure of 10 cm H2O and titrated to 16 cm H2O. In contrast to her original study, polysomnography showed continuous central apneas and moderate hypoxemia but only during NREM (Fig 3
, top, A, and bottom, B). Increasing the CPAP was well tolerated but was completely ineffective. Oxygen and CPAP were prescribed.