Meconium Aspiration Syndrome: An Insight

Abstract

Meconium aspiration syndrome (MAS) is respiratory distress in a newborn baby caused by the presence of meconium in the tracheobronchial airways. The aspiration of meconium stained amniotic fluid by the fetus can happen during antepartum or intrapartum periods and can result in airway obstruction, interference with alveolar gas exchange, chemical pneumonitis as well as surfactant dysfunction. These pulmonary effects cause gross ventilation-perfusion mismatching. To complicate matters further, many infants with MAS have primary or secondary persistent pulmonary hypertension of the newborn as a result of chronic in utero stress and thickening of the pulmonary vessels. Although meconium is sterile, its presence in the air passages can predispose the infant to pulmonary infection. MAS is essentially a clinical diagnosis and should always be suspected in a child with respiratory distress and meconium-stained amniotic fluid at delivery. Though a known entity for a long time, its management still remains contentious. Intubation and direct tracheal suction is performed when meconium is observed in the amniotic fluid and the infant is not vigorous. Subsequent management involves ventilation, surfactant instillation and lavage, inhaled nitric oxide and high frequency ventilation. The role of steroids continues to be controversial.

Golden hour of neonatal life: Need of the hour

“…The X-ray feature suggestive of air leak syndrome will be leakage of air from the alveoli into the extra-alveolar space like pneumothorax (air collection in pleural space), pneumomediastinum (collection of air in mediastinum), pneumopericardium (collection of air around heart in pericardium), and pulmonary interstitial emphysema (PIE) (presence of air in the lung interstitium) [ 232 – 234 ]. CXR in meconium aspiration syndrome typically shows diffuse, asymmetric patchy infiltrates, areas of consolidation, often worse on the right, hyperinflation and sometimes presence of air leak syndrome [ 235 ]. In case of perinatal asphyxia cord blood ABG or ABG within first hour will help us decide about starting of therapeutic hypothermia.…”

A Case of Meconium Aspiration Syndrome in a Bottlenose Dolphin (<i>Tursiops truncatus</i>) Calf

“…Meconium aspiration syndrome (MAS) is defined as a serious respiratory disorder of the infant born through meconium-stained amniotic fluid (MSAF) that cannot be otherwise explained; MAS is caused by exclusively aspiration of meconium in the airways during intrauterine gasping or during the first few breaths [1, 13, 15, 18]. MAS has been reported in human infants, neonatal calves [10] and piglets [5], and the occurrence is very rare in other species [6].…”

“…Meconium is a sticky dark green substance containing gastrointestinal secretions, bile, bile acids, mucus, pancreatic juice, intestinal juice, blood, swallowed vernix caseosa, lanugo and cellular debris [ 15 , 18 ]. Meconium aspiration syndrome (MAS) is defined as a serious respiratory disorder of the infant born through meconium-stained amniotic fluid (MSAF) that cannot be otherwise explained; MAS is caused by exclusively aspiration of meconium in the airways during intrauterine gasping or during the first few breaths [ 1 , 13 , 15 , 18 ]. MAS has been reported in human infants, neonatal calves [ 10 ] and piglets [ 5 ], and the occurrence is very rare in other species [ 6 ].…”

“…Fetal hypoxic stress and acidosis can lead to a vagal response with increased peristalsis and a relaxed anal sphineter, resulting in the passage of meconium into the amniotic fluid. In addition, fetal gasping movements during the later phase of asphyxia result in aspiration of the meconium [ 1 , 13 , 15 ]. The pathophysiology of MAS is remarkably complex, and several factors are involved including: (1) airway obstructions and atelectasis: (2) chemical pneumonitis with release of vasoconstrictive and inflammatory mediators: (3) inactivation of pulmonary surfactant [ 1 , 13 , 15 ].…”

Utility of amnioinfusion in deliveries complicated by meconium stained liquor: a randomized controlled trial

“…6 MAS occurs in about 5% of deliveries with meconium-stained amniotic fluid and death occurs in about 12% of infants with MAS. 7 Several measures have been described in order to prevent such a major life threatening complication.…”