A 2-hour-old term infant born through thick meconium-stained amniotic fluid presents with tachypnea (RR 68/min), intercostal retractions, and oxygen requirement. Chest X-ray shows patchy infiltrates with hyperinflation. Regarding the clinical features and management of MAS, all of the following statements are correct EXCEPT:

Explanation

## Clinical Management of Meconium Aspiration Syndrome **Key Point:** MAS management is primarily supportive; antibiotics are NOT routinely indicated unless there is clinical or laboratory evidence of bacterial infection. ### Radiologic and Pathophysiologic Features **High-Yield:** The classic CXR pattern in MAS shows: - Patchy, irregular infiltrates (chemical pneumonitis) - Hyperinflation with flattened diaphragms (air trapping) - Atelectasis alternating with overinflation - Possible pneumothorax or pneumomediastinum Hyperinflatation results from **ball-valve obstruction** — meconium plugs in small airways allow air entry during inspiration but trap air during expiration, leading to progressive lung overdistension. ### Complications of MAS | Complication | Mechanism | Management | |--------------|-----------|------------| | PPHN | Hypoxemia + pulmonary vasoconstriction | Inhaled NO, high-frequency ventilation, ECMO | | Pneumothorax | Barotrauma from hyperinflation | Chest tube if tension or respiratory compromise | | Pulmonary hemorrhage | Epithelial damage + pulmonary edema | Supportive care, surfactant | | Secondary infection | Bacterial colonization (if present) | Antibiotics only if evidence of infection | **Clinical Pearl:** PPHN occurs in 5–10% of MAS cases and is a major cause of morbidity and mortality. Inhaled nitric oxide (iNO) is the standard therapy. ### Antibiotic Use — The Critical Error **Warning:** Routine antibiotics in MAS are NOT recommended because: 1. Meconium aspiration is a **sterile** process (chemical pneumonitis, not infection). 2. Routine antibiotics increase antibiotic resistance without benefit. 3. Antibiotics should be reserved for cases with: - Maternal chorioamnionitis or prolonged rupture of membranes (PROM) - Clinical signs of sepsis (fever, lethargy, poor feeding) - Positive blood or CSF cultures - Elevated inflammatory markers (CRP, procalcitonin) with clinical suspicion **Mnemonic:** **MAS-ABC** = Meconium Aspiration Syndrome — **A**ntibiotics only if Bacterial infection suspected, **B**ased on clinical/lab evidence, **C**hemical pneumonitis is sterile. ### Surfactant Therapy **High-Yield:** Exogenous surfactant (e.g., poractant alfa, beractant) is beneficial in moderate-to-severe MAS: - Restores surfactant function inactivated by meconium - Improves oxygenation and lung compliance - Reduces need for ECMO by ~40% (based on trials) - Dosing: typically 100–200 mg/kg per dose; repeat dosing may be needed