Chapter 129: Aspiration of Foreign Material (Meconium Aspiration Syndrome, Aspiration Pneumonia)

MAS pathophysiology · Chemical pneumonitis · Airway obstruction · PPHN · NRP guidelines (no routine intubation) · Surfactant · iNO · ECMO · Postpartum aspiration (anatomic, swallowing)
🫁 Key fact: MAS occurs in 5% of meconium-stained infants; 30% require mechanical ventilation; mortality 3-5%.

🫁 Meconium Aspiration & Aspiration Pneumonia: Core Concepts

📊 MAS Epidemiology
Meconium-stained fluid in 10-15% births; MAS develops in 5%. Risk increases with postterm gestation (≥42 wk).
🧬 Pathophysiology
Airway obstruction (ball-valve → air trapping/pneumothorax), surfactant inactivation, chemical pneumonitis, and PPHN.
📷 CXR findings
Patchy infiltrates, coarse streaking, hyperinflation, flat diaphragm, pneumothorax/pneumomediastinum.
🩺 Clinical presentation
Meconium-stained infant, respiratory distress, cyanosis, ± HIE/multiorgan dysfunction. PPHN common.
⚕️ NRP guidelines
No routine intubation for meconium (even non-vigorous). Initial steps + PPV if apneic/bradycardic.
💊 Treatment
Supportive O2, CPAP, surfactant, iNO for PPHN, HFOV, ECMO for refractory hypoxemia.
⚠️ MAS complications: PPHN (25-50%), pneumothorax (15-30%), pulmonary air leaks, persistent hypoxemia, HIE, pneumonia.

🔍 Approach to meconium-stained newborn with respiratory distress

1
Delivery room assessment – Meconium-stained fluid. Is the infant vigorous? (strong respiratory effort, good tone, HR >100).
2
Initial steps (NRP) – Do NOT routinely intubate for meconium. Dry, warm, stimulate. If apneic or HR <100 → PPV.
3
Recognize MAS signs – Respiratory distress, cyanosis, retractions, grunting, hyperinflation, possible pneumothorax.
4
Assess for PPHN – Pre-ductal/post-ductal SpO2 gradient, echocardiogram. Hypoxemia out of proportion to CXR.
5
Evaluate for HIE – Asphyxia may coexist with MAS; neurologic exam and therapeutic hypothermia if criteria met.

📋 Stepwise management of meconium aspiration syndrome

1
Delivery room: no routine intubation – NRP 2020: even non-vigorous infants receive PPV if needed; no evidence for routine tracheal suction.
2
Respiratory support – Supplemental O2, nasal CPAP for mild-moderate distress. Intubation if severe hypoxemia or apnea.
3
Surfactant administration – May improve oxygenation; surfactant lavage not routine but bolus surfactant (100-200 mg/kg) beneficial.
4
PPHN management – Inhaled nitric oxide (iNO) 20 ppm. Optimize lung inflation (avoid hyperinflation). Sedation/paralysis if needed.
5
High-frequency ventilation (HFOV) – Rescue for refractory hypoxemia or air leak (pneumothorax, PIE).
6
ECMO – For severe MAS with OI >40 refractory to iNO and HFOV. Survival >90% in experienced centers.
📌 Antibiotics in MAS: If meconium aspiration, risk of bacterial pneumonia is low; antibiotics only if maternal risk factors or positive cultures. Not routine.

🧠 Rapid reflex prompts – Meconium aspiration & aspiration pneumonia

📌 When is intubation for meconium indicated?
Not routinely; current NRP does not recommend intubation even for non-vigorous infants.
📌 Most common complication of MAS?
Persistent pulmonary hypertension (PPHN) – up to 50% of severe cases.
📌 Chest X-ray finding in MAS?
Patchy infiltrates, coarse streaking, hyperinflation, flat diaphragm, +/- pneumothorax.
📌 First-line vasodilator for PPHN in MAS?
Inhaled nitric oxide (iNO) 20 ppm.
📌 How to reduce MAS incidence?
Avoid post-term delivery (>42 wk), treat maternal diabetes, intrapartum fetal monitoring.
📌 Postpartum aspiration: common cause in newborn?
Swallowing dysfunction (neurologic, prematurity) or anatomic (TEF, choanal atresia).
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