Intraperitoneal microdialysis : technique and results

University dissertation from Örebro : Örebro universitetsbibliotek

Abstract: Microdialysis has recently developed from a laboratory research method of animals to a useful clinical tool to evaluate parameters suggesting tissue ischemia. It is now used in neurosurgery, plastic surgery and liver transplantation.Shock and multiple organ failure after surgery are rare but serious complications with a high mortality rate and splanchnic ischemia is an early and important step in this development. Splanchnic ischemia is leading to increased permeability of the intestinal mucosa and to activation of macrophages. Subsequent release of inflammatory mediators like cytokines initiates shock, which may result in multiple organ failure and death. The importance of splanchnic hypoxia/ischemia is investigated in these five studies in relation to activation of cytokines (intraperitoneal and systemic) during a normal recovery and in case of surgical complications after major gastrointestinal surgery.Postoperatively the metabolic substances, glucose, pyruvate, lactate and glycerol were analysed and the LP ratio was calculated using microdialysis intraperitoneally and subcutaneously. Two studies are focused on the activation of the immunologic system by measurement of the cytokines TNF-, IL-6 and IL-10 and the relationship between LP ratio and the cytokines. Three studies are describing the performance of intraperitoneal microdialysis, different responses depending on the site of measurement, the difference between intraperitoneal and subcutaneous measurements and normal values in postoperative gastrointestinal surgery. Patients with clinical complications are described separately.No adverse effects of the intraperitoneal measurement technique were seen. An increase of the intraperitoneal LP ratio and decrease of glucose were in several cases preceding clinical complications. Intraperitoneal LP ratio, glucose and cytokines were higher in the abdominal cavity compared to subcutaneous and systemic measurements in a normal postoperative recovery. An intraperitoneal correlation between TNF-a and the LP ratio was found. Intraperitoneal concentrations of the cytokines and the LP ratio were decreasing in parallel during a normal postoperative recovery.The intraperitoneal inflammatory response is higher, during a normal postoperative recovery as well as in patients suffering from complications, compared to systemic findings, emphazising the importance of the gastrointestinal tract as the source of early immunological reactions postoperatively. IPM enables safe and sensitive analysis of glucose, pyruvate, lactate and glycerol from the intraperitoneal organs measured in the intraperitoneal fluid.Measurement of the LP ratio with microdialysis seems to detect early splanchnic hypoxia/ischemia that correlates to the intraperitoneal inflammation. IPM may have a future as an important clinical tool for monitoring patients at risk of developing postoperative surgical complications.

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