Undetected episodes of prolonged apnea and severe bradycardia in preterm infants.

Twenty-four-hour tape recordings of ECG and breathing movement were made on 14 preterm infants with prolonged apneic episodes. Despite apnea monitoring systems, 136/203 (67%) apneic episodes greater than or equal to 20 seconds in duration, including 19 episodes greater than or equal to 50 seconds in duration, were not recorded by nursing staff. Of 120 apneic episodes greater than or equal to 30 seconds, 100 (89%) were accompanied by bradycardia less than or equal to 100 beats per minute. Episodes of more marked bradycardia (less than or equal to 80 beats per minute and up to seven minutes in duration) occurred without cessation of breathing movement in 10/14 infants studied. Treatment with theophylline or aminophylline was associated with a reduction in the number of episodes of apnea greater than or equal to 20 seconds accompanied by bradycardia less than or equal to 80 beats per minute (P less than .001). Many prolonged episodes of apnea and bradycardia are going unnoticed in neonatal intensive care units. Further studies are required to investigate and overcome the causes of these failures.