RELATIONSHIP BETWEEN CONTINUOUS INFUSION OF FENTANYL CITRATE (FC) AND ARTERIAL PROSTANOID LEVELS. 2032

Acute respiratory difficulty is associated with FC, which is routinely used for pain relief in critically ill neonates. We examined the relationship between FC and systemic prostanoid levels in two groups of newborn piglets(1-3 days old), treated with either: a loading dose of FC (30 μg/Kg i.v.) over 15 minutes, followed by a continuous infusion of FC at 10 μg/Kg/hr for 6 hours (study group, n=6); or 5% dextrose at 6 mg/kg/min. (placebo group, n=8). Arterial blood was collected at 0 (pre-FC), 0.5, 2, 4 & 6 hours during infusion for measurement of PGE₂, 6-keto PGF_1α and TXB₂, by enzyme immunoassay. In the placebo (PB) group, the levels of prostanoids remained unchanged from baseline. In contrast, systemic PGE₂ levels in the FC group was substantially reduced (87%) at 30 minutes and remained reduced up to 6 hrs (p<0.001). Additionally, systemic 6-keto PGF_1α levels was more than 2-fold greater than baseline at 30 minutes (p<0.001), and at 2 hours(p<0.01). No change in TXB₂ levels was detected. Values are mean±SD. (**p<0.001, *p<0.01)Table

Table 1

We therefore conclude that these changes in systemic prostanoids by FC may contribute to bronchoconstriction, and may explain respiratory difficulty with infusion of FC in human newborn infants.