Magnesium therapy in infants with postneonatal apnea.

Idiopathic postneonatal apnea is defined here as a sudden, unexpected attack of apnea that first occurs after the infant has been discharged from the neonatal nursery to his home. Little has been published concerning the patient's physical and clinical laboratory findings during the acute episode. The present report of 20 infants with postneonatal apnea retrospectively addressed these parameters, including all investigations conducted for magnesium deficiency. The first episode of apnea occurred at 48 +/- 12.5 days of age and was unpredicted, transient, and self-limited. In the sickest infants, the apneic attack was a form of shock, with apnea, bradycardia, and often with acute respiratory distress, and/or neuromuscular hyperirritability. Laboratory findings in such infants were compatible with shock, including: acidosis, hemoconcentration, and hyperkalemia. Some infants showed high retention of parenteral Mg loads and received Mg therapy. Those receiving 5 or more days of Mg supplements were called 'Mg-treated'. Seven such patients were treated for 20.4 +/- 3.7 days. They were compared with 13 'Mg-untreated' patients who received less than 5 days of Mg therapy, 0.9 +/- 0.2 days. There was no known recurrence of apnea requiring resuscitation, or any rehospitalization for an apneic attack among the Mg-treated infants. Of the 13 Mg-untreated infants, 6 were readmitted for apnea at 90 +/- 37 days of age; 2 of these had a third admission for apnea. In conclusion, in its most severe form, postneonatal apnea is a shock-like episode that is self-limited, with a propensity to recur. Mg therapy appears to be associated with a reduction in recurrent apnea. This conclusion is corroborated by the significant reduction in recurrent apnea in the follow-up of a parallel study of 61 Mg-treated versus 139 Mg-untreated premature infants with idiopathic postneonatal apnea (p less than 0.001). Further study can be recommended.