Heart rate changes in convulsive and nonconvulsive neonatal apnea.

One hundred twelve apneic spells of at least 4 seconds' duration were monitored in 15 neonates; 77 episodes were associated with convulsive discharges on the electroencephalogram and 35 were not. Convulsive apnea did not occur in conjunction with bradycardia. Nonconvulsive apnea of less than 20 seconds' duration occurred in the presence of variable heart rates, but nonconvulsive apnea of 20 seconds or longer was nearly always associated with bradycardia.