Role of Endotracheal Suction on the Occurrence of Meconium Aspiration Syndrome in Non-vigorous Meconium Stained Babies

Overview

The purpose of this study is to evaluate the role of endotracheal suction on the occurrence of meconium aspiration syndrome in depressed meconium stained babies. Meconium aspiration syndrome (MAS) is believed to result from aspiration of meconium and consequent chemical pneumonitis. Meconium can be aspirated into the lungs in the womb as well. Meconium in the distal airways is not accessible to endotracheal (ET) suction which clears only the windpipe. Furthermore there is growing evidence in support of asphyxia-hypoxia-acidosis in the causation of lung disease. Moreover, in the absence of a clear role of ET suction in depressed meconium stained newborns, critical time could be lost in assessment, intubation and ET suction (range: 30 seconds to 1 min) which might delay the definitive step of ventilation for resuscitation of such babies that can potentially affect the outcome adversely.The utility or futility of endotracheal suction in preventing MAS in depressed meconium stained neonates has not been systematically studied and there is inadequate information in literature in favor or against this practice.Thus this study is an attempt to evaluate the effect of endotracheal suction on the occurrence of MAS in depressed full term neonates born through meconium stained amniotic fluid (MSAF).

Approximately 10-15% of deliveries are complicated by the passage of meconium around the time of delivery.An adverse intrauterine environment with resultant fetal asphyxia is proposed as the most common explanation for in-utero passage of meconium. 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 in an infant born through MSAF with compatible chest x-ray findings whose symptoms cannot be otherwise explained. Despite current interventions such as intubation and 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. There are various proposed mechanisms by which meconium causes lung injury, some of the important ones being * Mechanical obstruction of airways * Chemical pneumonitis * Vasoconstriction of pulmonary vessels * Inactivation of surfactant * Activation of compliment Finding of meconium below cords or in the trachea has been shown to be associated with development of MAS. This resulted in use of endotracheal suction along with oro-nasopharyngeal suctioning in all infants born to mothers with MSAF prior to the year 2000. Although, a number of studies performed did not show reduction in incidence of MAS and/or mortality even after performing oro-nasopharyngeal and endotracheal suction, the practice was continued due to lack of robust evidence. Subsequently, as a result of well performed randomized controlled trials and systematic review showing no effect of oro-nasopharyngeal suctioning on occurrence of MAS, this practice has been abandoned since the year 2005. ET suction is currently performed in depressed meconium stained neonates with the idea of removing meconium from the upper airways to relieve mechanical obstruction and to prevent subsequent development of chemical pneumonitis. Since meconium aspiration can occur in-utero as well and with time the aspirated meconium migrates peripherally, the effectiveness of ET suction post-delivery in clearing the airway is not clear. Furthermore, accumulating evidence points to potential role of hypoxia-asphyxia-acidosis with concomitant presence of meconium in the pathogenesis of lung disease. Current practice of Endotracheal suctioning in non-vigorous babies has not been systematically evaluated, till date. No studies have compared the incidence, severity and outcomes of MAS in 'suctioned versus non-suctioned' non vigorous meconium stained neonates. In addition, the procedure needs expertise to be completed in the stipulated time and has potential for complications like vocal cord injury, laryngeal edema, bleeding from upper airway secondary to trauma during the procedure and persistent hoarseness of voice even at six months of age. The rate of complications is more when performed by people with lesser expertise as this is a difficult skill to learn and master. In view of the foregoing the contribution of endotracheal suction in preventing MAS and its effect on severity of lung disease is not clear. Thus this study is an attempt to evaluate the role of endotracheal suction in non-vigorous meconium stained neonates.