Positive End Expiratory Pressure during Resuscitation of Premature Lambs Rapidly Improves Blood Gases without Adversely Affecting Arterial Pressure

摘要

Positive end expiratory pressure (PEEP) is important for neonatal ventilation but is not considered in guidelines for resuscitation. Our aim was to investigate the effects of PEEP on cardiorespiratory parameters during resuscitation of very premature lambs delivered by hysterotomy at ~125 d gestation (term ~147 d). Before delivery, they were intubated and lung fluid was drained. Immediately after delivery, they were ventilated with a Dr?ger Babylog plus ventilator in volume guarantee mode with a tidal volume of 5 mL/kg. Lambs were randomized to receive 0, 4, 8, or 12 cm H2O of PEEP. They were ventilated for a 15-min resuscitation period followed by 2 h of stabilization at the same PEEP. Tidal volume, peak inspiratory pressure, PEEP, arterial pressure, oxygen saturation, and blood gases were measured regularly, and respiratory system compliance and alveolar/ arterial oxygen differences were calculated. Lambs that received 12 cm H2O of PEEP died from pneumothoraces; all others survived without pneumothoraces. Oxygenation was significantly improved by 8 and 12 cm H2O of PEEP compared with 0 and 4 cm H2O of PEEP. Lambs with 0 PEEP did not oxygenate adequately. The compliance of the respiratory system was significantly higher at 4 and 8 cm H2O of PEEP than at 0 PEEP. There were no significant differences in partial pressure of carbon dioxide in arterial blood between groups. Arterial pressure was highest with 8 cm H2O of PEEP, and there was no cardiorespiratory compromise at any level of PEEP. Applying PEEP during resuscitation of very premature infants might be advantageous and merits further investigation.Abbreviations: AaDO2, alveolar-arterial oxygen difference; CPAP, continuous positive airway pressure; CRS, compliance of the respiratory system; Fio2, fraction of inspired oxygen; FRC, functional residual capacity; MAP, mean arterial pressure; Paco2, partial pressure of carbon dioxide in arterial blood; Pao2, partial pressure of oxygen in arterial blood; PEEP, positive end expiratory pressure; PIP, peak inspiratory pressure; RDS, respiratory distress syndrome; Sao2, oxygen saturation; VT, tidal volume