Effects of Postnatal Age and Aminophylline on the Maturation of Amplitude-Integrated Electroencephalography Activity in Preterm Infants

Abstract

Background: The use of amplitude-integrated electroencephalography (aEEG) is increasing during the neonatal intensive care of preterm infants. Objective: This prospective study was designed to assess factors that affect the maturation of aEEG activity in preterm infants with a gestational age (GA) of <32 weeks. Methods: aEEGs with cerebral function monitoring were performed weekly in preterm infants, and the recordings were evaluated and scored to assess the degree of continuity, the degree of sleep-wake cycling, and the amplitude of the lower border. Subjects with any of the following conditions were excluded: intraventricular hemorrhage or periventricular leukomalacia on cranial ultrasonography, sedation, hypotension, or respiratory instability (FiO₂ >50%). Results: The authors analyzed 207 recordings in 35 infants (GA 24–31 weeks, birth weight 440–1,980 g, postmenstrual age 25–38 weeks). At postmenstrual age 34–36 weeks, the aEEG total score was higher in preterm infants with a GA from 24 to 28 weeks than in less premature infants with a GA from 29 to 31 weeks (aEEG total score 12 vs. 10, p < 0.05). Logistic regression analysis revealed that the sleep-wake cycling was more prominent in infants with higher postnatal age (OR 3.32, 95% CI 2.40–4.59) or those receiving aminophylline (OR 3.28, 95% CI 1.06–10.08). Conclusions: The maturation of aEEG activity was found to be significantly correlated with postnatal age and with aminophylline use in clinically stable preterm infants. Most notably, aminophylline was found to be significantly associated with the degree of sleep-wake cycling as indicated by aEEG activity.