The CLP model of intra-abdominal sepsis was introduced by Wichterman, Baue, and Chaudry in 1980. The group published an insightful review of previous models and introduced a novel sepsis model still widely regarded as the gold standard for modelling polymicrobial sepsis today-the cecal ligation and puncture (CLP) model. Rats were fasted, Experimental Sepsis Models 37 their cecum was ligated distal to the ileocecal valve, the antimesenteric cecal surface was punctured twice with an 18G ½ needle, and received subcutaneous saline post-operatively. This model induced polymicrobial infection (blood cultures positive for Escherichia coli, Streptococcus bovis, Proteus mirabilis, Enterococcus, and Bacteroides fragilis) and bacteremia (peritoneal cavity fluid positive for the above microbes as well as Streptococcus viridians and Clostridium sporogenes) and a 70% mortality rate. Mildly ill rats sacrificed 10 hours following CLP demonstrated the early hyperdynamic phase of sepsis (increased blood flow to organs, hyperinsulinemia, and hyperglycemia) while rats sacrificed 16-24 hours post-operative represented a hypodynamic late septic state (decreased blood flow to organs, hypoinsulinemia, hypoglycemia, and high serum lactate levels) (3). The results of this model correlate with clinical sepsis conditions as patients who are initially normotensive, show an increase in cardiac output, have low peripheral resistance, and increased total oxygen consumption, conditions which reverse in late septic shock (3).Multiple aspects of the CLP procedure address the complex, of the clinical course of sepsis. CLP induces polymicrobial infection of the peritoneum with a localized infectious focus, release of bacteria and endotoxic molecular components of pathogens (pathogen-associated molecular patterns or PAMPs) into normally sterile areas in the host, and subsequent translocation of enteric bacteria into the bloodstream, modelling the stages of intraabdominal clinical sepsis (3). Under anaesthesia, the cecum is exposed and trauma is induced via a midline skin laparotomy and blunt dissection of the peritoneum to exteriorize the cecum. Avoiding damage to the mesenteric vessels, the cecum is ligated with suture distal to the ileocecal valve, punctured once or twice (through-and-though) from the mesenteric to anti-mesenteric direction halfway between the ligation and cecal end, and aspirated for trapped gasses (3). A small amount of fecal content is extruded to allow for patency of the puncture(s) and continuous flow of feces post-operatively. The cecum is returned into the peritoneal cavity taking care not to spread fecal content on the incision and the peritoneum and abdomen are closed separately with sutures (11).
