Recurrence of sleep apnea syndrome following tracheostomy. A shift from obstructive to central apnea.

This report describes an unusual case of severe obstructive sleep apnea and alveolar hypoventilation leading to hypersomnolence and cor pulmonale, which were corrected by tracheostomy. Four years later, after a 22.5-kg weight gain, nocturnal apneas of similar frequency, duration, and depth of desaturation reappeared but were totally central in origin. The central apneas were eliminated with home nocturnal positive-pressure ventilation via cuffed tracheostomy tube. Each time the patient's apneas were corrected (obstructive: tracheostomy; central: mechanical ventilation), daytime alveolar hypoventilation disappeared rapidly. Yearly right heart catheterizations and radionuclide ejection fractions documented pulmonary hypertension and right heart failure, with resolution following tracheostomy and recurrence after appearance of central apneas. The changes in hemodynamic status corresponded to the patient's weight, presence of apnea, daytime alveolar hypoventilation, and treatment of nocturnal oxyhemoglobin desaturation. This case illustrates the theory of a common etiology of both central and obstructive apnea through abnormal respiratory controller gain and points to several roles obesity may play in apnea.