BackgroundApnea of prematurity (AOP) is nearly universal among very preterm infants, but neither the apnea burden nor its clinical associations have been systematically studied in a large consecutive cohort.MethodsWe analyzed continuous bedside monitor chest impedance and electrocardiographic waveforms and oxygen saturation data collected on all NICU patients <35 weeks gestation from 2009–2014 (n=1211; >50 infant-years of data). “ABDs”, defined as central apnea ≥10 sec associated with both bradycardia <100 bpm and oxygen desaturation <80%, were identified using a validated automated algorithm.ResultsNumber and duration of apnea events decreased with increasing gestational age (GA) and post-menstrual age (PMA). ABDs were more frequent in infants <31 wks GA at birth but were not more frequent in those with severe ROP, BPD or severe IVH after accounting for GA. In the day before diagnosis of late-onset septicemia and necrotizing enterocolitis, ABD events were increased in some infants. Many infants continued to experience short ABD events in the week prior to discharge home.ConclusionsFrequency of apnea events is a function of GA and PMA in infants born preterm, and increased apnea is associated with acute but not with chronic pathologic conditions.

Background Periodic breathing (PB) is a normal immature breathing pattern in neonates that, if extreme, may be associated with pathologic conditions. Methods We used our automated PB detection system to analyze all bedside monitor chest impedance data on all infants <35 weeks’ gestation in the University of Virginia Neonatal Intensive Care Unit from 2009-2014 (n=1211). Percent time spent in PB was calculated hourly (>50 infant-years’ data). Extreme PB was identified as a 12h period with PB >6 standard deviations above the mean for gestational age (GA) and post-menstrual age (PMA) and >10% time in PB. Results PB increased with GA, with the highest amount in infants 30-33 weeks’ GA at about 2 weeks’ chronologic age. Extreme PB was identified in 76 infants and in 45% was temporally associated with clinical events including infection or necrotizing enterocolitis (NEC), immunizations, or caffeine discontinuation. In 8/28 cases of septicemia and 10/21 cases of NEC there was a >2-fold increase in %PB over baseline in the day prior to diagnosis. Conclusion Infants <35 weeks GA spend, on average, <6% of the time in PB. An acute increase in PB may reflect illness or physiological stressors or may occur without any apparent clinical event.

Background Periodic breathing (PB), regular cycles of short apneic pauses and breaths, is common in newborn infants. To characterize normal and potentially pathologic PB, we used our automated apnea detection system and developed a novel method for quantifying PB. We identified a preterm infant who died of SIDS and who, on review of her breathing pattern while in the NICU, had exaggerated PB. Methods We analyzed the chest impedance signal for short apneic pauses and developed a wavelet transform method to identify repetitive 10–40 second cycles of apnea/breathing. Clinical validation was performed to distinguish PB from apnea clusters and determine the wavelet coefficient cutoff having optimum diagnostic utility. We applied this method to analyze the chest impedance signals throughout the entire NICU stays of all 70 infants born at 32 weeks’ gestation admitted over a two-and-a-half year period. This group includes an infant who died of SIDS and her twin. Results For infants of 32 weeks’ gestation, the fraction of time spent in PB peaks 7–14 days after birth at 6.5%. During that time the infant that died of SIDS spent 40% of each day in PB and her twin spent 15% of each day in PB. Conclusions This wavelet transform method allows quantification of normal and potentially pathologic PB in NICU patients.