Temporal relationship between pauses in nasal airflow and desaturation in preterm infants

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.