To determine the incidence of seizure-like events in a cohort of infants born preterm as well as the prevalence of associated vital sign changes (heart rate [HR], respiratory rate, and pulse oximetry [SpO ₂ ]).

We performed prospective conventional video electroencephalogram monitoring on infants born at 23-30 weeks of gestational age during the first 4 postnatal days. For detected seizure-like events, simultaneously captured vital sign data were analyzed during the pre-event baseline and during the event. Significant vital sign changes were defined as HR or respiratory rate > ±2 SD from the infant’s own baseline physiologic mean, derived from a 10-minute interval before the seizure-like event. Significant change in SpO ₂ was defined as oxygen desaturation during the event with a mean SpO ₂ < 88%.

Our sample included 48 infants with median gestational age of 28 weeks (IQR 26-29) and birth weight of 1125 g (IQR 963-1265). Twelve (25%) infants had seizure-like discharges with a total of 201 events; 83% (10/12) of infants had vital sign changes during these events, and 50% (6/12) had significant vital sign changes during the majority of the seizure-like events. Concurrent HR changes occurred the most frequently.

Individual infant variability was observed in the prevalence of concurrent vital sign changes with electroencephalographic seizure-like events. Physiologic changes associated with preterm electrographic seizure-like events should be investigated further as a potential biomarker to assess the clinical significance of such events in the preterm population.