1844 EFFECT OF PGE2 ON CONTROL OF BREATHING IN THE NEONATAL PIGTET

Abstract

Prostaglandins (PG) and cyclo-oxygenase inhibitors influence fetal and neonatal respiration but the exact mechanism of this action is unknown. We evaluated the effects of PGE2 on control of breathing in 7 neonatal pigs (X ± SD; age 3.7±1.3 days; wt. 1.39±0.3 kg) sedated with PO Chloral Hydrate. Minute ventilation (VE) and airway occlusion pressure (Pocc) were measured in room air (RA), 5% CO2 and 10% O2 before and after 15-20 min. of PGE2 infusion ( 1 μug/kg/min.) Results were (X ± SD): PGE2 produced a depression of minute ventilation and ventilatory response to CO2 but did not alter the ventilatory response to 10 min. of hypoxia. Two animals developed apnea immediately after decreasing the FiO2 during PG infusion. Airway occlusion pressure with 5% CO2 was also lower during PG infusion than basal. Lung compliance and resistance did not change with PG. These results indicate that PGE2 reduces ventilation by central respiratory depression. While in some animals PGE2 may alter the immediate response to hypoxemia resulting in apnea, it does not change the ventilatory response to steady state hypoxemia.