Meconium Aspiration Syndrome

Name

Meconium aspiration syndrome (MAS) can also be referred to as neonatal aspiration of meconium.

Etiology

The cause of this syndrome is when there is meconium in an infant’s lungs before or after birth or with the first breath. Meconium is the first feces on an infant which is a dark green, tar-like substance. This syndrome is found more often in term or post-term patients thought to be caused by low amniotic fluid levels and diminished placenta function. In these situations the infant may not be getting enough oxygen which may stress the baby and the placenta. Some health issues of the mother may also cause stress to the infant which may lead to aspiration of meconium; for example, a mother with diabetes or hypertension bay add stress

Post term babies are at higher risk due to aging of the placenta, the organ that provides nourishment to the infant, which with age is unable to give the baby a sufficient amount of oxygen needed, which may then cause stress the fetus (Burke, 2012). Other risk factors may include preeclampsia (high blood pressure), oligohydramnios (deficiency of amniotic fluid), chorioamnionitis (inflammation of the fetal membranes), and positive pressure ventilation prior to clearing the airway.

Prevention

The prevention of meconium aspiration, healthcare providers as well as the carrying mother should pay close attention to the amount of stress put on the unborn infant. As stated previously high stress on the infant in utero may cause the infant to inhale causing aspiration of meconium. Also, initiating prompt delivery in the presence of fetal acidosis, late decelerations, or poor beat-to-beat variability (Behrman, 2004).

Meconium that is aspirated into the trachea bronchial tree has two potentially devastating effects on the neonate. They physical presence of meconium in the airways can lead to blockage of the airway and air trapping (Whitaker, 2001). Meconium trapped in the airway can lead to a disruption of ventilation and perfusion ratios and cause hypoxia and hypercabia. Gas exchange can also be impaired by meconium aspiration due to the cause of atelectasis. Trapped gas in the lungs may increase as the meconium creates a “ball-valve” effect that blocks the airway which may cause the lung to rupture. Another effect of meconium aspiration is an inflammatory response called chemical pneumonitis; the inflammation results in mucosal edema, decreasing lung compliance, and further impairment of gas exchange (Whitaker, 2001). Persistent pulmonary hypertension may result from asphyxiation in utero, these patients’ arterial blood gases may worsen, and blood flow continues to follow fetal pathways. Other effects of meconium aspiration include cyanosis without response to oxygen therapy, tachypnea, and pulmonary infection. Auscultation often reveals pulmonic systolic ejection clicks and a loud second heart sound (Whitaker,