Lung injury caused by aspiration of organophosphorus insecticide and gastric contents in pigs

ABSTRACT
Introduction: Patients who require mechanical ventilation after self-poisoning with ingested organophosphorus (OP) insecticides often die. Aspiration of stomach contents may contribute to lung injury and lethality. This study was designed to assess the severity of direct and indirect pulmonary injury created by pulmonary instillation of mixtures of OP insecticide, solvent (Solv), and porcine gastric juice (GJ), compared to controls.
Methods: Terminally anaesthetised minipigs (groups n=5) were exposed to sham bronchoscopy or given mixtures (0.5mL/kg) of: saline, GJ, OP insecticide and GJ (OP+GJ), or Solv and GJ (Solv+GJ), placed into the right lung, and monitored for 48h. Lung injury was assessed through analysis of bronchoalveolar lavage fluid (BALF), computed tomography and histopathology.
Results: OP+GJ created a direct lung injury consisting of neutrophil infiltration, oedema and haemorrhage, as well as indirect injury to the other lung. OP+GJ directly-injured lung parenchyma had increased concentrations of BALF protein, albumin, IL-6, IL-8 and C-reactive protein (CRP) at 24h (P<0.05), and BALF protein, albumin and CRP at 48h (p<0.05), when compared with controls. Aspiration of GJ produced similar direct effects to OP+GJ but less indirect lung injury. Lung injury was less severe after Solv+GJ, for combined lung histopathology scores (vs OP+GJ, p<0.05) and for the proportion of directly-injured lung that was poorly/non-aerated at 48h.
Conclusion: Pulmonary instillation of OP+GJ created more lung damage than controls or Solv+GJ. In patients with severe OP insecticide poisoning and reduced consciousness, early airway protection is likely to reduce pulmonary damage.