Pathophysiology of meconium aspiration includes what effect?

• A. Thick tar-like meconium can plug airways
• B. Meconium causes airway inflammation only
• C. Meconium reduces surfactant production
• D. Meconium infection leads to pneumonia

Answer: (A)

The main idea is that meconium aspiration causes a mechanical obstruction in the airways. When thick, tar-like meconium is inhaled, it tends to lodge in the smaller airways, plugging them and blocking ventilation. This airway obstruction creates areas that are poorly ventilated while the surrounding lung may become over-distended from trapped air, leading to significant ventilation–perfusion mismatch and hypoxemia.

Meconium also irritates the airways and contains substances that can inactivate surfactant, worsening lung compliance and promoting atelectasis and edema, but these are secondary effects. Infection and chemical pneumonitis can occur, yet the defining pathophysiology in the option is the airway plugging by the viscous meconium.