CENTRAL ALVEOLAR HYPOVENTILATION Dr. Cristian Guilleminault Standford. USA This syndrome is well codified and has been extensively studied-Sometime called Ondine‘s curse, it consists of the absence of appropriate ventilation during NREM sleep when stimulation of inspiratory medullary neurons is dependent of chemosensitivity. It is usually recognized during the first few days of life; the child when falling asleep changes color may become cyanotic and present respiratory pauses of variable duration. Arterial blood gazes show presence of CO2 retention, often associated with less marked hypoxemia with absence of indication of infection or lung diseases. The sleep laboratory confirm the diagnosis: polysomnography performed with measurement of end-tidal CO2 and transcutaneous CO2 electrode shows presence of central hypopnea an apnea and progressive increase in arterial CO2 during the entire sleep period. As infants sleep by short bouts, their blood gazes usually normalized more or less during the wake period, where they usually cry. But often there is persistence of some degree of PaCO2 abnormality. Diagnosis is affirmed by the sleep laboratory: Polysomnography shows presence of repetitive central apnea and hypopnea clearly seen during NREM sleep. There is simultaneous decrease of arousal responses with longer and longer events been monitored repetitive hypoxemia and progressive. During REM sleep an improvement of ventilation is noted, depending of the severity of the syndrome a disappearance of the repetitive events may be seen with improvement of hypoxemia and decrease in hypercapnia. However there is usually an overall increase in hypercapnia during the sleep period. There is usually an improvement of blood gazes during the crying periods but depending again on the severity of the syndrome blood gazes abnormalities may still be seen. Treatment is a challenge. Depending of the severity of the syndrome and the importance of the hypercapnia temporary intubation with mechanical ventilation may be succeeded by tracheostomy with negative pressure ventilation, but this means long hospitalization of a new born infant. Based on response to ventilatory tests and repeat PSG during temporary intubation and mechanical ventilation, nasal intermittent positive pressure ventilation (NIPPV) can be attempted. The most commonly tried initial IPPV system is bilevel with back-up rate. It has the advantage to provide a positive end expiratory pressure (PEEP) that negative pressure
ventilators do not provide and that volume ventilators do not provide either. If not successful a tracheostomy with mecanichal ventilation particularly during sleep may be needed. The rapid growth of the infant mandate repeat sleep evaluations. The issue of diaphragmatic pacing will come at a later age