Aspiration pneumonitis and pulmonary phospholipids

Area of Science:

• Pulmonary Medicine
• Toxicology
• Anesthesiology

Background:

• Peptic aspiration pneumonitis, or Mendelson's syndrome, is a severe lung injury.
• It occurs when gastric acid is inhaled into the lungs, often during anesthesia.

Purpose of the Study:

• To investigate the biochemical changes in the lungs following aspiration of gastric acid.
• To determine the role of specific lung phospholipids in the pathogenesis of Mendelson's syndrome.

Main Methods:

• Anesthetized dogs underwent endotracheal insufflation of 0.1 N HCl to induce lung damage.
• Pulmonary edema was assessed via gross examination and wet/dry lung weight ratios.
• Alveolar phospholipids were analyzed, focusing on lysophosphatidyl-choline (LPC) levels.

Main Results:

• Aspiration of HCl caused severe pulmonary edema and increased lung wet/dry weight ratios.
• Elevated surface tension was observed in lung wash samples.
• Lysophosphatidyl-choline (LPC) levels significantly increased in the affected lungs.

Conclusions:

• The study identifies lysophosphatidyl-choline (LPC) as a key factor in acid-induced lung injury.
• Increased LPC is strongly implicated as a cause of hemorrhagic pneumonia in Mendelson's syndrome.
• LPC's hemolytic properties likely contribute to the observed hemorrhaging.