Apnea of prematurity: theophylline v. caffeine.

During a fifteen month period, 401 two channel (heart rate and respiratory impedance), 12 hour pneumocardiograms on 277 preterm infants were performed. Each pneumocardiogram was evaluated according to the following set of criteria: prolonged apnea (apnea > 19 seconds or shorter if associated with heart rate of < 80bpm for > 2 seconds or observed cyanosis); short apnea (apnea 10-19 seconds); periodic breathing (normal respiratory pattern interrupted by > 2 breathing pauses of > 5 seconds during > 1 minute duration). Apnea density was used as prime measure in determining abnormal pneumocardiograms and was defined by total apnea time (seconds) x 100 divided by recording time while periodic breathing index defined by total periodic breathing time (minutes) x 100 divided by recording time. Sixty infants (24%) had apnea densities > or = 5 which prompted therapy with theophylline. Sixteen of these infants (27%) failed to resolve their apnea within 7 days (apnea density > or = 3) and were placed on caffeine citrate. Caffeine decreased the apnea density of fourteen of these infants (88%) to 0.8 (95% CI; 0-2.3). Efficacy of both methylxanthines to normalize the pneumocardiogram was similar (p = 0.5). Persistent apnea unresponsive to theophylline may respond to orally administered caffeine citrate.