To assess the incidence and impact of persistent apnea on heart rate (HR), oxygen saturation (SpO2), and brain tissue oxygenation index (TOI) over the first 6 months after term equivalent age in ex-preterm infants.Study design
Twenty-four preterm infants born between 27 and 36 weeks of gestational age were studied with daytime polysomnography at 2-4 weeks, 2-3 months, and 5-6 months post-term corrected age. Apneas lasting ≥3 seconds were included and maximal percentage changes (nadir) in HR, SpO2, and tissue oxygenation index (TOI, NIRO-200 Hamamatsu) from baseline were analyzed.Results
A total of 253 apneas were recorded at 2-4 weeks, 203 at 2-3 months, and 148 at 5-6 months. There was no effect of gestational age at birth, sleep state, or sleep position on apnea duration, nadir HR, SpO2, or TOI. At 2-4 weeks, the nadirs in HR (−11.1 ± 1.2 bpm) and TOI (−4.4 ± 1.0%) were significantly less than at 2-3 months (HR: −13.5 ± 1.2 bpm, P < .05; TOI: −7.5 ± 1.1 %, P < .05) and at 5-6 months (HR: −13.2 ± 1.3 bpm, P < .01; TOI: −9.3 ± 1.2%, P < .01).Conclusions
In ex-preterm infants, apneas were frequent and associated with decreases in heart rate and cerebral oxygenation, which were more marked at 2-3 months and 5-6 months than at 2-4 weeks. Although events were short, they may contribute to the adverse neurocognitive outcomes that are common in ex-preterm children.