EPISODES OF BRADYCARDIA DURING EARLY INFANCY IN THE TERM-BORN AND PRETERM INFANT

Objective.-To document the incidence of transient episodes of bradycardia in a group of healthy term and preterm infants during the first 1 to 6 months of life. Design.-Longitudinal polysomnographic study. Setting.-Sleep laboratory in a university-affiliated urban medical center. Participants.-Fourteen healthy term-born infants, nine preterm infants with apnea in the nursery, and 10 preterm infants without apnea. Infants with neonatal morbidity except apnea were excluded. Measurements.-Transient episodes of bradycardia (less-than-or-equal-to 100 beats per minute) were identified in 2- to 4-hour early evening polysomnographic tracings. The relationship with apnea, transcutaneous oxygen levels, and sleep state was determined. Results.-Transient episodes of bradycardia to 60 to 70 beats per minute were common, but there were no drops below 50 beats per minute. The incidence of transient episodes of bradycardia was inversely related to heart rate. Results for apneic and nonapneic premature infants were similar. Conclusions.-Transient episodes of bradycardia are considered normal reflex responses and are not related to risk for sudden infant death syndrome. These results have implications for the setting of monitor alarms.