Developing a systems approach to prevent meconium aspiration syndrome: lessons learned from multinational studies

Abstract

Passage of fetal bowel movement (meconium) is common (in about one out of six births), and in some the staining of the amniotic fluid is a sign of fetal distress. Inhalation of meconium (aspiration syndrome, in upto one out of five to eight such births) just before or at birth may be preventable by a coordinated approach by well-trained and informed birth attendants. Respiratory failure secondary to meconium aspiration syndrome (MAS) remains a major cause of morbidity and mortality in the neonatal population. Infants with hypoxemic respiratory failure because of MAS, persistent pulmonary hypertension of the newborn and pneumonia/sepsis have an increased survival with extracorporeal membrane oxygenation (ECMO). Other treatment options earlier limited to inotropic support, continuous airway pressure (CPAP), conventional ventilatory management, respiratory alkalosis, paralysis and intravenous vasodilators have been replaced by synchronized intermittent mandatory ventilation (SIMV), high-frequency oscillatory ventilation (HFOV), surfactant and inhaled nitric oxide (iNO). HFOV has been advocated for use to improve lung inflation while potentially decreasing lung injury through volutrauma. Other reports describe the enhanced efficacy of HFOV when combined with iNO. Subsequent to studies reporting that surfactant deficiency or inactivation may contribute to neonatal respiratory failure, exogenous surfactant therapy has been implemented with apparent success. Recent studies have shown that iNO therapy in the neonate with hypoxemic respiratory failure can result in improved oxygenation and decreased need for ECMO. However, these innovative interventions are costly, require a sophisticated infrastructure and are not universally accessible. In this paper, a context of systems-approach for prenatal, natal and postnatal management of babies delivered through meconium stained amniotic fluid (MSAF) so that adverse outcomes are minimized and the least number of babies require innovative ventilatory support is described. Previously reported data from a single urban perinatal center (Philadelphia, PA, USA), over a 6-year period (1995–2000), demonstrated that 14.5% (3370/23175 of live births babies were delivered with MSAF. These data also showed that 4.6% of babies (155/3370) with MSAF sustained MAS. Overall, 26% of babies (40/155) with MAS needed ventilatory support (or 0.17% of all live births); of these, only 20% (8/40 or 0.035% of live births) needed innovative ventilatory support. None died or needed ECMO. These data describe the components for a systems approach to prevent and manage adverse outcomes related to MSAF at the regional level II or III perinatal center. Replication of a similar strategy may be more relevant to cost containment and be a safer approach for neonates at risk for MAS-related respiratory failure. This paper assess the evidence for pivotal steps needed to prevent MAS and ensuing neonatal death and disease in the context of diverse perinatal health services.