Gastric Tonometry versus Oxygen Derived Variables as Predictors of Multiorgan ) • Dysfunction and Death in Septic Patients

Abstract

Sepsis is a systemic inflammatory response to infection. Inflammatory reaction is characterized by production of various inflammatory mediators including inflammatory cytokines, PAF and arachidonic acid metabolites. Endogenous mediators activate various inflammatory cells. They also activate coagulation cascade, complement system, increase nitric oxide production, increase capillary permeability and change vascular 'tone. As a result of disturbances in microcirculation, severe oxygen dept occurs at the parenchymal level which eventually leads to MODS.

Gut is thought to play a major role in the pathogenesis of sepsis and MODS. As a result of deranged barrier function of GIT, bacteria and toxins in the lumen may reach systemic circulation and • trigger release of various inflammatory mediators. In addition, microbial products may leak into submucosa with activation of gut associated lymphoid tissue; thus, the gut acts as a mediator generating organ.

Gut barrier • is a complex system of structural and physiological defenses. It includes epithelium itself, micro­ biological flora, various enteric secretions and gut associated •network of lymphocytes. Deranged barrier function may occur as a • :result of hypoxia induced by hypoperfusion or by endotoxins. Other factors ;which may lead to ,deranged barrier .function include "mUCOSal cacidosis, -nitric coOxide, cytokines and :release 'Ofreactive oxygen intermediates during ischemia- reperfusion. ATP depletion is.thought to be the final pathway leading to epithelial dysfunction.

Global indices of tissue oxygenation e.g. arterial lactate concentration and oxygen .derived variables may not reflect local tissue oxygenation particularly in the presence of abnormal vasoregulation and abnormal distribution of blood flow.