PRETERM BABOONS WITH HYALINE MEMBRANE DISEASE (HMD) DEMONSTRATE SIGNIFICANT IMPROVEMENT IN OPENING AND PEAK PRESSURES BY THE THIRD DAY

Abstract

Ventilated preterm baboons (140±2da) with HMD show a significant reduction in opening and peak pressures on pressure volume curves on the third day (74±2 hr) compared to initial studies (3±1hr). Thirteen preterm baboons (140±2da) were delivered by Cesarean section, resuscitated, and ventilated with a conventional neonatal ventilator (Bear Cub) or one of 2 high-frequency ventilators. After ketamine and succinylcholine intravenously the intubated animals were tested in a constant volume plethysmograph with an esophageal balloon in place. The inspiratory limb of the pressure volume curves at 0.5 Hz were analyzed for the opening pressure, defined as the pressure at the point of departure from an isovolumetric transpulmonary pressure change. The peak transpulmonary pressure was defined as the highest pressure required to ventilate the animal. Opening and peak pressures were significantly improved by the third day. Differences due to ventilator type were not apparent. Changes in opening and peak pressures may be a sensitive measure of improvement in HMD in preterm baboons.