Hypoxic arousal responses in infants with bronchopulmonary dysplasia.

Infants with bronchopulmonary dysplasia have a high incidence of sudden, unexplained death in the postneonatal period, yet the cause of these deaths is unknown. Frequent episodes of clinically unsuspected arterial oxygen desaturation have recently been described in infants with bronchopulmonary dysplasia. We hypothesized that infants with bronchopulmonary dysplasia who experience frequent episodes of hypoxia may have abnormal arousal responses to these hypoxic episodes. We studied 12 infants with bronchopulmonary dysplasia at 41.4 +/- 1.3 weeks postconceptional age. Hypoxic arousal responses were performed during quiet sleep at an inspired oxygen tension of 80 mm Hg for a maximum of three minutes or until arousal occurred. Of 12 infants, 11 (92%) aroused normally to the hypoxic challenge. However, all infants required vigorous stimulation and supplemental oxygen after the initial arousal response. Of 12 infants with bronchopulmonary dysplasia, eight (67%) experienced prolonged apnea with bradycardia, and four of 12 (33%) required brief ventilatory assistance (bag and mask) to restore normal breathing. Abnormal pneumographic findings did not predict the occurrence of these prolonged periods of apnea and bradycardia following hypoxia. We conclude that an abnormal response to hypoxia following arousal may lead to prolonged apnea and bradycardia in infants with bronchopulmonary dysplasia. We speculate that the inability to recover from this hypoxia may result in sudden death in these infants.