Combined central alveolar hypoventilation and upper airway obstruction: Treatment by tracheostomy and diaphragm pacing

Abstract

Long-term pacing of the diaphragm by electrical stimulation of the phrenic nerve has been successfully employed since 1966 in the treatment of patients with alveolar hypoventilation of central origin. Patients were selected for pacing on the basis of arterial blood gas levels indicating hypoventilation, abnormal ventilatory responses to hypercapnia and hypoxia, and characteristic clinical features. The coexistence of central alveolar hypoventilation and sleep-associated upper airway obstruction was detected in 14 patients. Recordings of several physiologic parameters were made during sleep to monitor changes in ventilatory function. Periodic apnea was observed in all patients. Three types were identified: apnea of central origin, that due to upper airway obstruction or a combination of the two. Pacemaker related apneas were also noted. Pacing the diaphragm eliminated apnea of central origin, accentuated apnea due to upper airway obstruction and, in two patients, both of whom had prolonged episodes of central apnea, pacing induced upper airway obstruction. Tracheostomy was performed for the relief of upper airway obstruction in 13 patients. Abnormal ventilatory responses to hypercapnia and hypoxia persisted in five of six patients studied. Of 12 patients studied after tracheostomy nine continued to show marked hypoventilation during sleep and three showed only mild hypoventilation; nocturnal pacing is being continued in these three patients to prevent a recurrence of alveolar hypoventilation. Our studies indicate that upper airway obstruction frequently accompanies central alveolar hypoventilation; the determination of their relative importance requires a ventilatory control study and a carefully monitored sleep study. In patients with combined central alveolar hypoventilation and upper airway obstruction whose condition is resistant to medical therapy, combined tracheostomy and diaphragm pacing are indicated.