Sindrome de Aspiración Meconial
Approach to Infants Born Through Meconium Stained Amniotic Fluid: Evolution Based on Evidence?
Munmun Rawat y cols
Department of Pediatrics, University at Buffalo, Buffalo, New York
Am J Perinatol 2018;35:815-822. DOI 10.1055/s-0037-1620269
Meconium is a term derived from the Greek word "mekoni"(poppy juice or opium) after its black tarry appearance. Given the long-standing relationship between meconium staining of amniotic fluid, birth asphyxia, neonatal depression, and persistent pulmonary hypertension of the newborn (PPHN), the finding of meconium- stained amniotic fluid (MSAF) at delivery is a major clinical concern in perinatal care. MSAF occurs in 8 to 25% of all births of which 20 to 30% infants are depressed, and 5% develop meconium aspiration syndrome (MAS).1 Although the incidence of MAS has decreased in recent years in developed countries, it continues to be associated with perinatal asphyxia resulting in morbidity and mortality in resource-poor settings.
Background MAS is a clinical diagnosis that includes delivery through MSAF with respiratory distress, a characteristic appearance on a chest radiograph and lack of an alternative diagnosis to explain respiratory distress. Most infants born through MSAF
Abstract Meconium-stained amniotic fluid (MSAF) during delivery is a marker of fetal stress. Neonates born through MSAF often need resuscitation and are at risk of meconium aspiration syndrome (MAS), air leaks, hypoxic-ischemic encephalopathy, extracorporeal membrane oxygenation (ECMO), and death. The neonatal resuscitation approach to MSAF has evolved over the last three decades. Previously, nonvigorous neonates soon after delivery were suctioned under the vocal cords with direct visualization technique using a meconium aspirator. The recent neonatal resuscitation program (NRP) recommends against suctioning but favors resuscitation with positive pressure ventilation of nonvigorous neonates with MSAF. This recommendation is aimed to prevent delay in resuscitation and minimize hypoxia-ischemia often associated with MSAF. In this review, we discuss the pathophysiology, evolution and the evidence, randomized control trials, observational studies, and translational research to support these recommendations. The frequency of ECMO use for neonatal respiratory indication of MAS has declined over the years probably secondary to improvements in neonatal intensive care and reduction of postmaturity. Changes in resuscitation practices may have contributed to reduced incidence and severity of MAS. Larger randomized controlled studies are needed among nonvigorous infants with MSAF. However, ethical dilemmas and loss of equipoise pose a challenge to conduct such studies.