Intervenção precoce versus intervenção tardia com lavado broncoalveolar e surfactante em modelo experimental de síndrome de aspiração de mecônio

摘要

Introduction: meconium aspiration syndrome is a cause of severe respiratory distress and mortality in term neonates. Due to meconium´s obstructive effect on the airways and its inhibitory action over the surfactant system, treatment with bronchoalveolar lavage and surfactant replacement have been evaluated in recent years. The best timing for the procedure is yet to be determined. Objective: to compare the effect of early and late administration of bronchoalveolar lavage with diluted surfactant followed by a supplementary dose of surfactant carried out in a piglet model of meconium aspiration syndrome. Methods: 15 newborn piglets were studied. The animals were mechanically ventilated with fixed settings throughout the study. Meconium aspiration syndrome was induced by instillation of 5 ml/kg of meconium diluted to 20% in isotonic saline, and afterwards the piglets were randomly allocated to one of the following groups: group I (n=5) - control; group II (n=5) - bronchoalveolar lavage with diluted surfactant (15 ml/kg) followed by a supplementary dose of alpha poractant surfactant (Curosurf®) 100 mg/kg – early administration; group III (n=5) - bronchoalveolar lavage with diluted surfactant (15 ml/kg) followed by a supplementary dose of alpha poractant surfactant 100 mg/kg – late administration. Arterial blood gases were measured six times at specific intervals during the six hours of the study. Results: mean PaO2 before immediate and late interventions were 52. 60±13. 33 and 66±32. 27 mmHg (p=0. 658); 30 minutes after each of the therapeutic procedures 96. 80±33. 07 and 101. 40±86. 74 mmHg (p=0. 894); and three hours following each intervention 122. 80±76. 79 and 142. 20±113. 71 mmHg (p=0. 672), respectively. The improvement in oxygenation observed three hours after the procedure was statistically significant both in the early [DPaO2=70. 20±23. 67 (p=0. 013)] and in the late [DPaO2=92. 48±35. 16 (p=0. 022)] intervention groups, and this was not observed in the control group. Conclusion: Bronchoalveolar lavage with diluted surfactant followed by a supplementary dose of surfactant administered three hours after the induction of disease improved oxygenation in a similar way as did the immediate administration of the same treatment in an experimental model of meconium aspiration syndrome. Both immediate and late interventions improved oxygenation when compared to a control group.