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.