Fully covered self-expandable metal stent placed over a stapled colon anastomosis in an animal model: A pilot study of colon metabolism over the stent.

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.

Altered mRNA Expression Due to Rectal Perforation in a Porcine Model - A Pilot Study.

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.

Total resuscitative endovascular balloon occlusion of the aorta causes inflammatory activation and organ damage within 30 minutes of occlusion in normovolemic pigs.

BACKGROUND: Resuscitative endovascular balloon occlusion of the aorta (REBOA) causes physiological, metabolic, end-organ and inflammatory changes that need to be addressed for better management of severely injured patients. The aim of this study was to investigate occlusion time-dependent metabolic, end-organ and inflammatory effects of total REBOA in Zone I in a normovolemic animal model. METHODS: Twenty-four pigs (25-35 kg) were randomized to total occlusion REBOA in Zone I for either 15, 30, 60 min (REBOA15, REBOA30, and REBOA60, respectively) or to a control group, followed by 3-h reperfusion. Hemodynamic variables, metabolic and inflammatory response, intraperitoneal and intrahepatic microdialysis, and plasma markers of end-organ injuries were measured during intervention and reperfusion. Intestinal histopathology was performed. RESULTS: Mean arterial pressure and cardiac output increased significantly in all REBOA groups during occlusion and blood flow in the superior mesenteric artery and urinary production subsided during intervention. Metabolic acidosis with increased intraperitoneal and intrahepatic concentrations of lactate and glycerol was most pronounced in REBOA30 and REBOA60 during reperfusion and did not normalize at the end of reperfusion in REBOA60. Inflammatory response showed a significant and persistent increase of pro- and anti-inflammatory cytokines during reperfusion in REBOA30 and was most pronounced in REBOA60. Plasma concentrations of liver, kidney, pancreatic and skeletal muscle enzymes were significantly increased at the end of reperfusion in REBOA30 and REBOA60. Significant intestinal mucosal damage was present in REBOA30 and REBOA60. CONCLUSION: Total REBOA caused severe systemic and intra-abdominal metabolic disturbances, organ damage and inflammatory activation already at 30 min of occlusion.

Aortic balloon occlusion (REBOA) in pelvic ring injuries: preliminary results of the ABO Trauma Registry.

EndoVascular and Hybrid Trauma Management (EVTM) has been recently introduced in the treatment of severe pelvic ring injuries. This multimodal method of hemorrhage management counts on several strategies such as the REBOA (resuscitative endovascular balloon occlusion of the aorta). Few data exist on the use of REBOA in patients with a severely injured pelvic ring. The ABO (aortic balloon occlusion) Trauma Registry is designed to capture data for all trauma patients in hemorrhagic shock where management includes REBOA placement. Among all patients included in the ABO registry, 72 patients presented with severe pelvic injuries and were the population under exam. 66.7% were male. Mean and median ISS were respectively 43 and 41 (SD ± 13). Isolated pelvic injuries were observed in 12 patients (16.7%). Blunt trauma occurred in 68 patients (94.4%), penetrating in 2 (2.8%) and combined in 2 (2.8%). Type of injury: fall from height in 15 patients (23.1%), traffic accident in 49 patients (75.4%), and unspecified impact in 1 patient (1.5%). Femoral access was gained pre-hospital in 1 patient, in emergency room in 43, in operating room in 12 and in angio-suite in 16. REBOA was positioned in zone 1 in 59 patients (81,9%), in zone 2 in 1 (1,4%) and in zone 3 in 12 (16,7%). Aortic occlusion was partial/periodical in 35 patients (48,6%) and total occlusion in 37 patients (51,4%). REBOA associated morbidity rate: 11.1%. Overall mortality rate was 54.2% and early mortality rate (≤ 24 h) was 44.4%. In the univariate analysis, factors related to early mortality (≤ 24 h) are lower pH values (p = 0.03), higher base deficit (p = 0.021), longer INR (p = 0.012), minor increase in systolic blood pressure after the REBOA inflation (p = 0.03) and total aortic occlusion (p = 0.008). None of these values resulted significant in the multivariate analysis. In severe hemodynamically unstable pelvic trauma management, REBOA is a viable option when utilized in experienced centers as a bridge to other treatments; its use might be, however, accompanied with severe-to-lethal complications.

Early Metabolic and Inflammatory Intraperitoneal Changes After Rectum Perforation.

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.

Is the aortic size index relevant as a predictor of abdominal aortic aneurysm? A population-based prospective study: the Tromsø study.

Objectives. The normal aortic diameter (AD) varies with gender, age and body surface area (BSA). The aortic size index (ASI) is defined as the AD divided by BSA. The primary aim of this study was to investigate if ASI is a predictor of development AAA, and to compare the predictive impact of ASI to that of the absolute AD. Design. Population-based prospective study including 4161 individuals (53.2% women) from the Tromsø study with two valid ultrasound measurements of the AD and no AAA at baseline (Tromsø 4, 1994). The primary outcome was AAA (AD ≥30 mm) in Tromsø 5 (2001). A secondary outcome was aortic growth of >5 mm over 7 years. Estimates of relative risk were calculated in logistic regression models. The main exposure variable was ASI. Adjustments were made for age, gender, smoking, body mass index, total and high-density lipoprotein (HDL) cholesterol, and hypertension. Results. In total, 124 incident AAAs (20% among women) were detected. In adjusted analyses, both ASI and AD were strong predictors of AAA, with similar results for men and women. Both ASI and AD were also significant predictors of aortic growth >5 mm. In comparison, AD was superior to ASI as a predictor of both endpoints. Conclusions. ASI was a significant predictor of both AAA development and aortic growth of >5 mm for both men and women, but not a better predictor of either outcomes compared to the AD. The role of ASI compared to the AD as a predictor of AAA development seems to be limited.

Results of postoperative microdialysis intraperitoneal and at the anastomosis in patients developing anastomotic leakage after rectal cancer surgery.

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.

No-touch technique for radiocephalic arteriovenous fistula--surgical technique and preliminary results.

PURPOSE: The radiocephalic arteriovenous fistula (RC-AVF) has significant failure rates due to occlusions and failure to mature. The size and quality of the veins are considerable limiting factors for the procedure. The aim of this pilot study was to describe the No-Touch technique (NTT) to create RC-AVF and present the results up to 1 year of follow-up. METHODS: Thirty-one consecutive patients who were referred for surgery for a RC-AVF were included (17 men, mean age 63 years, range 35-84) and operated by NTT where the vein and artery were dissected with a tissue cushion around it. Twenty-two patients had small veins or arteries (≤2 mm), 12 patients had a small cephalic vein (≤2 mm), and the mean distal cephalic vein diameter was 2.4 mm (range 1.0-4.1 mm). RESULTS: Technical surgical success and immediate patency were obtained in all patients. Clinical success was achieved in 23 of the 27 (85%) patients who required hemodialysis. The proportion of primary patency at 30 days and 6 months was 84% and 64%, respectively. Secondary patency at 30 days and 6 months was 97% and 83%, respectively. At 1-year follow-up, primary patency was 54% and secondary patency was 80%. There was no major difference in patency due to preoperative vein diameter. CONCLUSIONS: The results of this study indicate that NTT can be used for primary radio-cephalic fistula surgery with very good results. This method offers the potential to create a RC-AVF in patients who are not usually considered appropriate for a distal arm fistula due to a small cephalic vein.

Intra-abdominal hypertension--an experimental study of early effects on intra-abdominal metabolism.

BACKGROUND: The main aim of this experimental study was to investigate the early effects of intra-abdominal hypertension (IAH) on intra-abdominal metabolism and intestinal mucosal blood flow to evaluate whether metabolites can serve as markers for organ dysfunction during IAH. METHODS: A swine model was used, and the animals were anesthetized and ventilated. Fifteen animals were subjected to IAH of 30 mm Hg for 4 hr by carbon dioxide insufflation. Seven animals served as controls. Hemodynamic data, arterial blood samples, and urine output were analyzed. Intraluminal laser Doppler flowmetry measured intestinal mucosal blood flow. Glucose, glycerol, lactate, and pyruvate concentrations and lactate-to-pyruvate (l/p) ratio were measured intraperitoneally and intramurally in the small intestine and rectum using microdialysis. RESULTS: IAH lowered the abdominal perfusion pressure by 12-18 mm Hg, reduced the intestinal mucosal blood flow by 45-63%, and decreased urine output by 50-80%. In the intervention group, glycerol concentrations increased at all locations, pyruvate concentrations decreased, and the l/p ratio increased intraperitoneally and intramurally in the small intestine. Control animals remained metabolically stable. Glucose and lactate concentrations were only slightly affected or unchanged in both the groups. CONCLUSIONS: IAH reduces intestinal blood flow and urinary output and causes early metabolic changes, indicating a discrete shift toward anaerobic metabolism. Intraperitoneal microdialysis may be useful in the early detection of impaired organ dysfunction with metabolic consequences in IAH and abdominal compartment syndrome.

Intraperitoneal metabolic consequences of supraceliac aortic balloon occlusion in an experimental animal study using microdialysis.

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 (l/p) 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 l/p ratio from 18 at baseline, peaking at 46 in early reperfusion. SMA occlusion and reperfusion tended to increase the i.p l/p ratio, peaking at 36 in early reperfusion. ABO increased the i.p glycerol concentration from 87 µM at baseline to 579 µM 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 l/p 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.