To Örebro University

BACKGROUND: Anastomotic leakage is the most serious and unwelcome complication in rectal surgery. It has a great impact on postoperative morbidity and mortality. In this pilot study, changes of mRNA expression in blood were analyzed in an animal model designed to imitate anastomotic leakage.

MATERIALS AND METHODS: Twelve pigs were randomized into two groups: A sham-operated control group and an experimental group in which iatrogenic rectal perforation was performed. The changes in the mRNA expression at 4 hours after creating the perforation were studied. Microarray analysis was performed using Gene Chip whole porcine genome array. mRNA expression of 19,124 genes was investigated.

RESULTS: Significantly increased levels of genes with a fold change greater than 2 were found, including 276 coding for unknown proteins and 48 coding for known proteins. Eleven of those which coded for known proteins were up-regulated with a fold change >4.

CONCLUSION: Eleven known genes were highly up-regulated after rectal perforation. These genes were mainly involved in inflammatory response, intracellular signaling and cell membrane regulation. Their corresponding proteins might potentially be clinical biomarkers of anastomotic leakage and should be evaluated in further clinical studies.

Background and Aim: Anastomotic leakage (AL) in colorectal resection and primary anastomosis is a common and feared complication. Fully covered self-expandable metal stents (FCSEMSs) have been used for the treatment of AL. It is still unknown whether FCSEMSs affect anastomosis healing negatively by causing ischemia. In an animal study, we investigated the metabolic effects over a FCSEMS covering a stapled colon anastomosis.

Methods: Seven pigs were investigated using microdialysis after laparotomy, colon resection, and anastomosis with stent placement. Measurements were done at the proximal and distal ends of the anastomosis and at a reference catheter placed at the small intestine. Measurements of glucose, pyruvate, lactate, glycerol, and the lactate/ pyruvate ratio (L/P) were carried out.

Results: Lactate and L/P were significantly higher at the oral part of the anastomosis, while glucose showed a small declining tendency. At the distal part of the anastomosis, glucose decreased significantly after the resection but did not reach zero. Lactate increased significantly whereas L/P increased only slightly. Glycerol levels were stable.

Conclusion: Colon resection caused initially hypermetabolism in the intestinal ends next to the resection site. This hypermetabolism neither deteriorated nor turned into ischemia during the initial postoperative course, but the start of hypoxemia could not be excluded during the study and after the placement of an FCSEMS.

BACKGROUND: Splanchnic vasodilation by inodilators is an argument for their use in critical cardiac dysfunction. To isolate peripheral vasoactivity from inotropy, such drugs were investigated, and contrasted to vasopressors, in a fixed low cardiac output (CO) model resembling acute cardiac dysfunction effects on the gastrointestinal tract. We hypothesized that inodilators would vasodilate and preserve the aerobic metabolism in the splanchnic circulation in low CO.

METHODS: In anaesthetized pigs, CO was lowered to 60% of baseline by partial inferior caval vein balloon inflation. The animals were randomized to placebo (n = 8), levosimendan (24 μg kg-1 bolus, 0.2 μg kg-1 min-1, n = 7), milrinone (50 μg kg-1 bolus, 0.5 μg kg-1 min-1, n = 7), vasopressin (0.001, 0.002 and 0.006 U kg-1 min-1, one hour each, n = 7) or norepinephrine (0.04, 0.12 and 0.36 μg kg-1 min-1, one hour each, n = 7). Hemodynamic variables including mesenteric blood flow were collected. Systemic, mixed-venous, mesenteric-venous and intraperitoneal metabolites were analyzed.

RESULTS: Cardiac output was stable at 60% in all groups, which resulted in systemic hypotension, low superior mesenteric artery blood flow, lactic acidosis, and increased intraperitoneal concentrations of lactate. Levosimendan and milrinone did not change any circulatory variables, but levosimendan increased blood lactate concentrations. Vasopressin and norepinephrine increased systemic and mesenteric vascular resistances at the highest dose. Vasopressin increased mesenteric resistance more than systemic, and the intraperitoneal lactate concentration and lactate/pyruvate ratio.

CONCLUSION: Splanchnic vasodilation by levosimendan and milrinone may be negligible in low CO, thus rejecting the hypothesis. High dose vasopressors may have side effects in the splanchnic circulation.

Every year inn Sweden more than 6000 individuals are diagnosed with colorectal cancer and more than 5000 operations are performed. Anastomotic leakage (AL) is the most dreaded complication in colorectal surgery and has a great impact on postoperative morbidity and mortality. 

In Study I, an iatrogenic rectal perforation was performed on an experimental group of pigs, in order to imitate AL and compared with a control group which had a sham operation over a 10-hours follow-up with intraperitoneal microdialysis (IPM) and cytokines. Glucose levels were lower in the experimental group at 4 hours and lactate and lactate/pyruvate ratios (L/P) were higher in the experimental group at 7 hours. Intraperitoneal (IP) Interleukine 6 (IL6) and Interleukine 10 (IL10) were higher in the experimental group at 10 hours and blood IL6 was higher in the experimental group at 4 hours. IPM and cytokines thus seem to react early after rectal perforation. 

Study II was a prospective observational study in which 7 patients with AL after surgery were compared with 13 patients without complications during the first 7 postoperative days with IPM, and intravenous and IP cytokines. In patients who later developed AL, IP lactate and L/P were higher immediately after surgery, while glycerol levels were lower. At the anastomosis higher L/P in AL patients were found after the fifth postoperative day. Intravenous and IP IL6 was higher in the leakage group. 

In Study III, mRNA expression in blood was analyzed in an animal model designed to imitate AL. Significantly increased levels of 276 genes were found and 11 of the 48 genes which coded for a known protein were highly up-regulated.

In Study IV, the metabolic effects of a fully covered self-expandable metal stent (FCSEMS) over a colorectal anastomosis were investigated with IPM, after laparotomy, colon resection and anastomosis with stent. Lactate and L/P rise at the oral part of the anastomosis were significantly higher, while glucose showed a small tendency toward numerically declining values. At the distal part of the anastomosis glucose decreased significantly after the resection but did not reach zero. Lactate increased significantly while L/P slightly increased. This suggest that hypermetabolism occurs in the intestinal ends next to the resectate, but even a start of hypoxemia cannot be excluded after the placement of a FCSEMS.

Purpose: Anastomotic leakage (AL) is the most dreaded complication in rectal surgery. It has a great impact on postoperative morbidity and mortality. This animal model, in which we have studied postoperative metabolic and inflammatory changes, is designed to imitate an AL.

Methods: Twelve pigs were randomized into 2 groups. In the experimental group, an iatrogenic rectal perforation was performed, with the control group having a sham operation. The 2 groups were followed for 10 hours after operation with regard to vital parameters, arterial lactate, and cytokines interleukin (IL) 1, IL6, and IL10 in the blood and intraperitoneally. Intraperitoneal microdialysis analyses of glucose, lactate, glycerol, and pyruvate were performed and the lactate/pyruvate ratio was calculated.

Results: Glucose levels were lower in the experimental group after 4 hours. After 7 hours, lactate and lactate/pyruvate ratio was higher in the experimental group. At the same time intraperitoneal cytokines IL6 and IL10 were higher in the experimental group. Blood samples showed higher IL6 after 7 hours in the experimental group.

Conclusion: In this study, several significant differences between the groups in metabolic and inflammatory values were detected. Further clinical studies are recommended to evaluate the importance of intraperitoneal metabolic and inflammatory analyses as a diagnostic tool for early identification of an AL.

Objective: The aim of the study was to find laboratory samples for early diagnosis of anastomotic leak.

Summary background data: Anastomotic leakage after rectal cancer surgery is a severe complication with high mortality. Outcome is highly dependent on early diagnosis.

Methods: 29 patients were investigated postoperatively after having undergone low anterior resection due to cancer recti. Patient outcomes were divided into three groups: Anastomotic leak in 7 patients, other complications in 9 patients and 13 patients who were free of complications. Patients were monitored every 6^th hour with blood and intraperitoneal samples in order to identify laboratory markers for early detection of anastomotic leakage. An anastomotic leak index was created, a scoring system where points count for values higher than reference values of CRP and interleukin 6 in blood and intraperitoneal lactate, lactate/pyruvate ratio and interleukin 6 were measured at 18, 24, 42 and 48 hours postoperatively.

Results: Significant differences between groups were found regarding CRP, Interleukin 6, fibrinogen and D-dimer in blood. Intraperitoneal differences were found not only in lactate and lactate/pyruvate ratio measured by microdialysis, significant differences in interleukin 6, interleukin 10 and tumour necrosis factor-α could also be demonstrated between the groups. The anastomotic leak index had a sensitivity and specificity of 86% (p=0.0007).

Conclusions: The most important factor was time after operation. No laboratory parameter in itself could predict an anastomotic leak but the anastomotic leak index was a useful tool in the monitoring and assessment of clinical outcome.

Mini abstract: Patients with anastomotic leak after rectal surgery were monitored with higher intraperitoneal cytokines and lactate/pyruvate ratio. The results suggest intraperitoneal microdialysis combined with blood samples of CRP and IL 6 as a feasible method for early diagnosis of anastomotic leak.

Introduction: Anastomotic leakage postoperatively in patients operated with rectum resection and primary anastomosis is a common and feared complication. We have studied seven patients with an anastomotic leakage after surgery and compared them with 13 patients without complications.

Methods: Metabolic measurements with microdialysis were done during the first seven postoperative days, with measurements of glucose, pyruvate, lactate and glycerol. The lactate/pyruvate ratio was calculated. Measurements were performed subcutaneously, intraperitoneally and at the anastomosis. The inflammatory cytokines, IL 6 and IL 10, were measured intravenously and intraperitoneally 48 hours postoperatively.

Results: Intravenous and intraperitoneal IL 6 were higher in the leakage group. Around the small intestine (intraperitoneally), we found that patients developing anastomotic leakage had higher lactate and lactate/pyruvate ratio immediately after surgery. They also showed lower glycerol levels. At the anastomosis, we found higher lactate and lactate/pyruvate ratio in anastomotic leak patients after the fourth postoperative day.

Conclusions: The results indicate that a possible mechanism behind an anastomotic leakage is an impaired circulation and thus insufficient saturation to the small intestine peroperatively. This develops into an inflammation both intraperitoneally and intravenously, which, if not reversed, spread within the gastrointestinal tract. The colorectal anastomosis is the most vulnerable part of the gastrointestinal tract postoperatively and hypoxia and inflammation may occur there, and an anastomosis leakage will be the consequence.

Background: To investigate the effects of supraceliac aortic balloon occlusion (ABO) and superior mesenteric artery (SMA) occlusion on abdominal visceral metabolism in an animal model using intraperitoneal microdialysis (IPM) and laser Doppler flowmetry.

Methods: A total of 9 pigs were subjected to ABO and 7 animals were subjected to SMA occlusion for 1 hour followed by 3 hours of reperfusion. Seven animals served as controls. Hemodynamic data, arterial blood samples, urinary output, and intestinal mucosal blood flow (IBF) were followed hourly. Intraperitoneal (i.p) glucose, glycerol, lactate, and pyruvate concentrations and lactate-to-pyruvate (lip) ratio were measured using IPM.

Results: Compared with the baseline, ABO reduced IBF by 76% and decreased urinary output. SMA occlusion reduced IBF by 75% without affecting urinary output. ABO increased the i.p lip ratio from 18 at baseline, peaking at 46 in early reperfusion. SMA occlusion and reperfusion tended to increase the i.p lip ratio, peaking at 36 in early reperfusion. ABO increased the i.p glycerol concentration from 87 mu M at baseline to 579 p,M after 3 hours of reperfusion. SMA occlusion and reperfusion increased The i.p glycerol concentration but to a lesser degree.

Conclusions: Supraceliac ABO caused severe hemodynamic, renal, and systemic metabolic disturbances compared with SMA occlusion, most likely because of the more extensive ischemia-reperfusion injury. The intra-abdominal metabolism, measured by microdialysis, was affected by both ABO and SMA occlusion but the most severe disturbances were caused by ABO. The i.p lip ratios and the glycerol concentrations increased during ischemia and reperfusion and may serve as markers of these events and indicate anaerobic metabolism and cell damages respectively.