Effects of morphine and midazolam on sleep-wake cycling in amplitude-integrated electroencephalography in post-surgical neonates ≥32 weeks of gestational age

Background: Studies of children who undergo major non-cardiac surgery in the neonatal period are needed so that subsequent abnormal neurodevelopment can be better understood. Objective:It was the aim of our study to describe the influence of analgesic and sedative medication on the predominant background pattern and the development of sleep-wake cycling (SWC), as measured on amplitude-integrated electroencephalography (aEEG), in newborn infants born ≥32 weeks' gestation after major non-cardiac surgery. Methods:This prospective study included infants ≥32⁺⁰ weeks' gestation admitted to the Neonatal Intensive Care Unit at The Royal Children's Hospital in Melbourne who were undergoing major non-cardiac surgery. Data on morphine and midazolam given after surgery were recorded and the BrainZ Monitor was applied post-operatively. The maximum levels of morphine and midazolam were assessed as predictors of time to aEEG outcomes using linear regression. Results: Forty-seven eligible infants were included. Emergence of SWC was observed at a mean of 13 h after surgery. The maximum dose of morphine or midazolam was not predictive of time to either any or developed SWC. Conclusions: Despite high doses of morphine and midazolam, SWC was observed on aEEG in neonates ≥32 weeks' gestational age soon after major non-cardiac surgery. The aEEG background pattern was not affected by the maximum dose of either morphine or midazolam.