Abstract 1077 Poster Session I, Saturday, 5/1 (poster 11)

Many infants being discharged from NICU continue to have frequent apnea. Many such infants also experience frequent and prolonged acid gastro-esophageal reflux. It is unclear whether there is any association between these two phenomena, or whether routine evaluation for either respiratory patterns or g-e reflux is warranted prior to discharge of the formerly preterm infant.

Methods: Infants of less than or equal to 32 weeks gestation born between July 1997 and August 1998 were considered for enrollment. Following informed parental consent a 12 hour cardiorespirogram (CRG) was performed with continuous esophageal pH monitoring. Positioning of the pH probe, at the junction of the mid- and lower thirds of the esophagus, was confirmed by chest x-ray, the probe was calibrated prior to each usage; apple juice feeds were not used. CRG included airflow monitoring by thermistor for diagnosis of obstructive apnea, as well as heart rate, chest movement and oximeter. Tracings were analyzed by a semi-automated methodology (Edentech®) and apneas of greater than 10 seconds were recorded, as well as the occurrence of bradycardia or desaturation. Infants were usually nursed side-lying with the head of the bed elevated 15 to 20 degrees.

Results: 45 infants, mean birth weight 1412 (SD 745)g were studied at an average postmenstrual age of 37.2 weeks (SD 3.5). The pH monitoring demonstrated acid reflux (pH<4.0) on at least one occasion in all of the infants. Prevalence of reflux was between <1% and 41% of the 12 hour record, with a median of 4.6% (inter-quartile range 0.5 to 9%). The number of reflux episodes ranged from 1 to 143, (median 23) and the duration of the individual events ranged from 1 to 84 minutes. The number of apneas (>10s duration) ranged from 0 to 71, median 6 in the 12 hour study. There was no correlation between apnea frequency or severity and g-e reflux frequency or duration. This held true for all apneas and when analyzed for only mixed and obstructive apneas. Restricting the analysis to longer apneas (>15s) had no effect on these results.

We analyzed the traces to determine whether apnea was more common during the 5 minutes after the start of a reflux episode than during the 5 minutes priot to each episode. There was no difference in apnea frequencies between these 2 periods.

Conclusion: Acid reflux in the formerly preterm infant at discharge is frequent and may be prolonged. There does not appear to be any association between g-e reflux and apnea on pre-discharge evaluation. The relationship between apnea of prematurity and acid reflux deserves future investigation