Apneas are common in preterm infants in the NICU. Since they are thought to be due to developmental immaturity, they should resolve by term. To determine whether these apneas have resolved by term, we monitored at home 252 preterm infants (≤34 wks GA; BW ≤1750 g) from 34-56 wks post conceptional age(PCA). The home monitor contained an inductance plethysmograph, ECG, and pulse oximeter, and it recorded events with central or obstructive apneas ≥16 sec and/or heart rate <80 bpm for ≥5 sec. For infants 34-37 wks PCA, 45% had at least one prolonged apnea (>20 sec), and 10% had >9 prolonged apneas/100 hrs of monitor use. For infants 38-41, 42-45, and 46-49 wks PCA, 37%, 25%, and 11% respectively had at least one prolonged apnea. The 95th percentile for longest apnea ranged from 34 sec at 34-37 wks PCA to 23 sec at 46-49 wks PCA. The longest apnea was 72 sec. Across all PCAs, 67% of prolonged apneas had 3 or more obstructed breaths (mixed apneas). Over 40% of prolonged apneas were associated with oxygen desaturations (<90%), but <10% were associated with bradycardia. We conclude that preterm infants at home have a high incidence of prolonged apneas up to 49 wks PCA; most apneas are mixed apneas; and many are associated with desaturation, but few with bradycardia. We speculate that respiratory control remains immature past term in preterm infants. The combination of immature respiratory control, the propensity for obstructive apneas, and hypoxia may in part explain the increased risk for SIDS in preterm infants. [Supported by NICHD; HD 28971, HD29073, HD29060, HD29067, HD29071, HD34625, and HD29056].
(Spon by: T.G. Keens)
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The Journal of Pediatrics (1998)