Faecal peritonitis in the rat. An experimental model for evaluation of surgical and adjuvant therapies

Wistar rats were equipped with two central venous catheters used for parenteral nutrition/antibiotics and blood sampling. The rats were conditioned in special cages and given a meat pellet diet to achieve a bowel flora more similar to man. When the animals after two weeks were adjusted to life in cages, meat pellets and indwelling non-functioning venous catheters, peritonitis was induced with a standardized 3 mm caecal perforation without any ligation or devascularization. Within few hours the animals were severe septic and blood cultures were positive in all with a mixed flora of gram-negative coliforms and anaerobic bacteroides. Important occurrence of circulating endotoxin was detected and found to increase gradually till death. Without any treatment this form of septic peritonitis gave a 100% mortality. Total parenteral nutrition (TPN) reduced mortality to 50%. Substitution of TPN with a simple saline/glucose solution gave the same survival rate demonstrating the importance of fluid supply and crystalloids during the early phase of septicaemia. Intravenously given antimicrobial agents active against anaerobes (tinidazole) and aerobes (cefotaxim) will in combination reduce mortality to less than 15%. The lethal effect of a 3 mm caecal perforation was almost abolished when TPN was added to this combination of antimicrobial agents. Continuous peritoneal irrigation did not increase survival rate.