Approach to Infants Born Through Meconium Stained Amniotic Fluid: Evolution Based on Evidence?

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.

Neonatal Life Support 2020 International Consensus on Cardiopulmonary Resuscitation and Emergency Cardiovascular Care Science With Treatment Recommendations

“…Meconium-stained amniotic fluid is present in 5% to 15% of all deliveries and is more common in neonates who are nonvigorous at birth. 35,36 Approximately 3% to 5% of neonates born through meconium-stained amniotic fluid develop meconium aspiration syndrome (MAS), which remains a significant cause of neonatal morbidity and mortality, particularly in developing countries. 37 Optimal management of neonates born through meconium-stained amniotic fluid remains a topic of debate.…”

Outcomes of endotracheal suctioning in non-vigorous neonates born through meconium-stained amniotic fluid: a systematic review and meta-analysis

“…(3) Review articles, case reports, letters to the editor, commentaries, and conference abstracts (42 articles) and non-RCTs (33 articles). (4) No investigation of the effects of ETS in non-vigorous infants born through MSAF (5 articles). Finally, four studies were included for further meta-analysis, [31][32][33][34] with no additional articles identified in the review of bibliographies of the included studies.…”

Approach to the Connection between Meconium Consistency and Adverse Neonatal Outcomes: A Retrospective Clinical Review and Prospective In Vitro Study

“…Approximately 1% to 12% of neonates with MSAF will develop MAS [ 22 , 23 , 24 ], which is associated with various serious complications, such as persistent pulmonary hypertension (PPHN), long-term respiratory issues [ 7 , 25 , 26 ], neurodevelopmental problems [ 17 , 19 , 20 , 27 , 28 , 29 ], and mortality [ 6 ]. MAS is a multifaceted disease, characterized by airway obstruction, surfactant dysfunction, and pulmonary inflammation [ 30 ]. Aspirated meconium that obstructs the airway impacts the infant’s oxygenation capacity [ 20 , 21 ], leading to the development of pneumothorax [ 22 ], pulmonary hypertension [ 23 ], and chemical pneumonitis [ 24 ], all of which can contribute to the occurrence of severe acute hypoxia, impaired neural development, and death [ 25 , 26 ].…”

“…Although the administration of exogenous surfactant improved lung functions in an animal model of MAS [ 35 ], this approach is supported by limited data, and clinical trials of exogenous surfactant administration did not show significant reductions in MAS-associated mortality or other morbidities [ 36 , 37 ]. An important feature of newborn lungs exposed to meconium is the presence of an inflammatory response [ 38 ], in which inflammatory cells and cytokines, such as tumor necrosis factor (TNF)-α, interleukin (IL)-1 β , IL-6, and IL-8, are activated by meconium to initiate pulmonary inflammation [ 30 ], and increased inflammatory indices are detected in cases of severe MAS [ 39 ]. Pathological examinations in MAS cases have revealed typical inflammatory pneumonitis, characterized by epithelial disruption, proteinaceous exudation with alveolar collapse, and cellular necrosis [ 40 ].…”