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- Hörer, Tal, 1971-
(författare)
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Early detection of major surgical postoperative complications evaluated by microdialysis
- 2013
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Major abdominal surgery may be followed by postoperative complications, especially in the elderly and patients with co morbidities as diabetes mellitus and obesity. Some of the most feared complications as anastomotic leakage, abdominal infections, abdominal compartment syndrome (ACS) and intestinal ischemia can lead to sepsis, systemic inflammatory response syndrome (SIRS) and multiple organ dysfunction syndrome (MODS) with high morbidity and mortality. This thesis evaluates intraperitoneal microdialysis (IPM) as a method for early detection of surgical complications. IPM measures extracellular metabolites as lactate, pyruvate, glycerol and glucose. The lactate/pyruvate (l/p) ratio describes the current relationship between aerobic and anaerobic metabolism. Glycerol is a degradation product of lipolysis from fat and a part of the cell membrane and released when cell injury occurs. In Paper I, evaluation of IPM in patients with and without diabetes mellitus and obesity during 48 hours after abdominal surgery did not show any difference in l/p ratio and glycerol levels compared to a control group. Paper II investigated the first two days after abdominal surgery in patients with major complications using IPM. L/p ratio was higher and glycerol was lower. Paper III used IPM in the immediate postoperative period in patients after endovascular repair for ruptured abdominal aortic aneurysm (rEVAR). Patients who required decompression due to intraabdominal hypertension (IAH) with organ failure had higher l/p ratio and glycerol. Paper IV investigated the effects of Aortic Balloon Occlusion (ABO) and Superior Mesenteric Artery (SMA) occlusion for one hour followed by three hours reperfusion in an animal model. ABO had a pronounced effect on the hemodynamic state. I.p l/p ratio increased during ischemia and decreased on reperfusion while glycerol increased on reperfusion and the effect was less pronounced in the SMA group. In conclusion, IPM monitoring of l/p ratio and glycerol indicates serious postoperative complications at an early stage. The l/p ratio increases or is continuously high while glycerol seems to have a more complex pattern. Diabetes and obesity do not influence the results.
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| 2. |
- Stenbäck, Anders, 1971-
(författare)
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Studies of Experimental Bacterial Translocation
- 2005
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- One of the main obstacles to maintaining patients with short bowel syndrome on parenteral nutrition, or successfully transplanting these patients with a small bowel graft, is the many severe infections that occur. Evidence is accumulating that translocating bacteria from the patient’s bowel causes a significant part of these infections. In this thesis bacterial translocation is studied in a Thiry-Vella loop of defunctionalised small bowel in the rat. Bacterial translocation to the mesenteric lymph nodes (MLNs) occurs in almost 100% of the rats after three days. No systemic spread of bacteria is observed unless there is additional immunosupression with depletion of Kupffer cells in the liver. However, blocking the function of α/β T cells does not increase the translocation. Removal of MLNs does not either aggravate bacterial translocation in the Thiry-Vella loop model. Conversely, after small bowel transplantation translocating bacteria spread systemically if the MLNs are removed. The Thiry-Vella loop should also be a suitable model for the testing of potentially translocation-inhibiting substances. Reinforcement of the intestinal barrier with glutamine or phosphatidylcholine proved insufficient in decreasing bacterial translocation. Even selective bowel decontamination with tobramycin failed to abolish bacterial translocation. Thus, it seems that the driving force for translocation in this model is strong regardless of the relatively small trauma of intestinal defunctionalisation. Flow cytometric studies of the immune cells in the spleen MLNs showed a decrease in MHC class II positive T cells in the MLNs of the Thiry-Vella loop. Concurrently the number of macrophages increased with time as observed by immunohistochemistry. The fraction of MHC class II negative macrophages increased in the spleens of rats treated with glutamine. In conclusion, the Thiry-Vella loop model offers possibilities of immunological as well as mechanistic studies on bacterial translocation from small intestine.
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