Physiological recordings were undertaken to study the temporal relationship between apnea, defined as pauses in nasal airflow (PNA), and desaturation in preterm infants. Seventeen infants with a history of apnea of prematurity were studied on 21 occasions. Median (range) birthweight was 1,180 g (575-2,475) and gestation was 30 weeks (26-33). Median age at time of study was 10 days (range, 2-52). Arterial beat to beat oxygen saturation (SaO(2)), photoplethysmographic waveform, electrocardiogram, abdominal and ribcage breathing movements, and nasal airflow were recorded. Falls in SaO(2) > or = 3% occurring during or after a PNA > or = 4 seconds were recorded. Episodes of periodic breathing were excluded from this analysis. Four hundred and sixteen episodes of PNA and desaturation were analyzed. Application of a definition of "outliers" for non-parametric data suggested an association when the desaturation occurred up to 7.20 seconds after the end of the PNA for infants nursed in air. For infants on oxygen treatment, a temporal association was suggested when desaturation occurred up to 9.76 seconds after the end of PNA.
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