Comparison Of Surfactant Lung Lavage With Standard Care In The Treatment Of Meconium Aspiration Syndrome

Meconium is an odourless, thick, blackish green material first demonstrable in the foetal intestinal tract during the third month of gestation. Approximately 10-15% of deliveries are complicated by the passage of meconium around the time of delivery. The risk of meconium stained amniotic fluid (MSAF) is strongly correlated with gestational age. An adverse intrauterine environment with resultant foetal asphyxia is proposed as the most common explanation for MSAF.

Aspiration of meconium into the tracheo-bronchial tree with the onset of respiration results in meconium aspiration syndrome (MAS). MAS is defined as respiratory distress with compatible chest x-ray finding in an infant born through MSAF whose symptoms cannot be otherwise explained. Despite current interventions such as intubation with tracheal suction, it is estimated that 5-20 % of infants born through MSAF develop MAS. It represents a leading cause of perinatal morbidity. Approximately 50% of the infants with MAS require mechanical ventilation; 15%-30% develop pulmonary air leaks and 5%-12% die.

The pathophysiology of meconium aspiration syndrome includes airway obstruction, surfactant inactivation, inflammation and pulmonary hypertension. Meconium itself inactivates the surfactant in the alveoli and its presence also causes secondary surfactant deficiency as meconium is toxic to type 2 alveolar cells which secrete surfactant. There is no specific treatment recommended for meconium aspiration syndrome .Treatment for MAS is generally supportive and includes supplemental oxygen as needed, assisted ventilation to maintain lung volume and improve gas exchange, and circulatory support with volume resuscitation and vasopressor infusions to maintain adequate perfusion. Successful treatment of meconium aspiration relies on effective meconium removal without inactivating or washing out surfactant, followed by appropriate ventilator care.

Surfactant replacement in neonates with severe meconium aspiration syndrome has been shown to improve oxygenation and reduce the severity of respiratory failure, air leaks and need for extracorporeal membrane oxygenation.

Surfactant replacement alone does not remove the meconium present in the airways and hence multiple doses may be required. Therefore an effective strategy to improve outcome in neonates with MAS needs to not only remove meconium but also retain the surfactant for adequate lung expansion and function.

Lung lavage using diluted surfactant has recently been shown to be an alternative to bolus therapy in treating MAS. This has advantage of removing surfactant inhibitors from alveolar space, in addition to augmenting surfactant concentration in alveolar space. Initial pilot case series using surfactant lung lavage have shown promise and there is a need to systematically study this in a RCT. The same has also been expressed in the literature on this subject. Hence the purpose of this prospective randomized controlled trial is to compare the efficacy of surfactant lung lavage over standard therapy in the treatment of meconium aspiration syndrome.