Morphological and functional evaluation of distal esophagus of rabbits submitted to esophageal infusion with caustic soda

The ingestion of caustic substances is an important emergency situation, because of its serious consequences. Purpose: To study morphological and functional alterations of the esophagus in rabbits submitted to esophageal infusion of caustic soda (NaOH). Methods: The 88 rabbits studied were divided into 4 groups: G, (n=22) were submitted to esophageal infusion with distilled water. G(2), G(3) and G(4) were submitted to esophageal infusion of 2%,4% and 6% NaOH respectively. Morphological alterations were studied in 12 animals from each group and manometric alterations in the remaining 10. An analysis was made of lower esophageal sphincter (LES) pressure, number and amplitude of contractions in the distal third of the esophagus. These studies were performed before (moment M1) and at 30 minutes, 6 hours, and 24 hours after (moments M2, M3, and M4, respectively) esophageal infusion. Results: Morphological evaluation: G1 - no alterations; G2 - edema, hyperemia, and ecdysis; G3 - enlarged calibre of esophagus, ulcers, ecdysis of mucosa; G4 - lesions similar to G3, but more intense, areas of extensive hemorrhage at M3 and M4. Functional evaluation: LES was higher at M2; the number of distal third lower esophageal contractions in G3, and G4 was lower; and the contraction amplitude was lower in G4. Conclusions: 1) Esophageal infusion with caustic soda in rabbits is a good experimental model for studying caustic esophagites. 2) Esophageal infusion with NaOH caused lesions in the esophageal wall, with gravity proportional to solution concentration; 3) Infusion caused LES spasm at M2, and reduced both contraction number and amplitude in the distal third of the esophagus.