Acute pancreatitis as a model of sepsis.

Severe acute pancreatitis has many similarities to sepsis syndrome and septic shock. The haemodynamic features of cardiovascular instability, reduced ejection fraction and decreased systemic vascular resistance are indistinguishable in each of these conditions. In addition there are many striking similarities in the cytokine and inflammatory mediator profiles, suggesting that the haemodynamic abnormalities may result from the same pathogenic mechanisms, albeit as a result of different inflammatory stimuli. Although septic complications of severe acute pancreatitis do arise these are usually late features and in the early phase of a severe attack there is sterile pancreatic necrosis. Evidence suggests that the important cytokines in the development of complications and multiple organ failure in severe acute pancreatitis are tumour necrosis factor-alpha, interleukin-1, interleukin-6 and interleukin-8. In addition, endotoxin and other important inflammatory mediators including platelet activating factor and phospholipase A2 are implicated in the development of complications in both severe acute pancreatitis and sepsis. Patients with severe acute pancreatitis are not an entirely homogeneous group but in terms of pathogenesis and complications of their disease they have much more in common with each other than the patients who are collected under the unifying diagnosis of 'sepsis'. The similar clinical and biochemical features between severe acute pancreatitis and sepsis make the former an excellent model for studying the pathogenesis of the sepsis syndrome.