Bronchoalveolar lavage plus surfactant in a piglet model of Meconium Aspiration Syndrome

Meconium aspiration syndrome (MAS) is an important cause of morbidity and mortality in the neonatal period. Surfactant function is severely affected by specific components of meconium: in fact, in severe MAS, surfactant synthesis decreases, uptake and recycling are altered, and direct toxicity to alveolar cells may occur. Bronchoalveolar lavage (BAL) and surfactant replacement could represent a therapeutic approach to MAS, as preliminarily suggested by some clinical studies. The use of BAL was first tried with normal saline to remove meconium from the airways, but the effect of this therapeutical approach is still controversial, since it may cause deterioration in lung damage. However, it has been suggested that damage to the lung might be ameliorated by later use of exogenous surfactant.
A Brazilian group conducted an experimental study in a piglet model of MAS in order to evaluate the effects of BAL with normal saline followed by supplementary surfactant.
In total 15 newborn piglets were used in the study. The animals were ventilated with fixed settings. After inhalation of 4 ml/kg of diluted meconium, the piglets were randomized into three groups: group I (n = 5) underwent tracheal aspiration without BAL; group II (n = 5) was treated with BAL with normal saline (15 ml/kg); and group III (n = 5) was treated with BAL with normal saline (15 ml/kg) followed by a supplementary dose of surfactant. Arterial blood gas samples were obtained 30 min and 6 h after the inhalation of meconium.
Results show that a significant increase of PaO2 values at 6 h after treatment was only observed in group III (from 51±13 to 189±115 mmHg; p=0.04). At this time, PaO2 in group III was significantly higher than in group II (189±115 and 37±11 mmHg, respectively; p=0.023) and showed a borderline significance when compared to group I (p=0.066). The results of this experimental study suggest that BAL with saline followed by a supplementary dose of surfactant may improve oxygenation with a sustained effect over 6h. However, further studies with bigger sample size are needed to confirm the difference with the control group.
There are still many unanswered questions about the treatment of severe meconium aspiration with surfactant or BAL. In this experimental study, treatment with BAL was provided 30 min after meconium aspiration. In a clinical setting, vigorous treatments for MAS usually begin much later. Moreover, the combined treatment of severe MAS with surfactant and various techniques of ventilation as synchronized intermittent mandatory ventilation, continuous positive airway pressure, and high-frequency ventilation should be explored in further experimental and clinical studies. Such studies will be necessary before safe recommendations can be made.

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