OBES SURG (2014) 24:675–683 DOI 10.1007/s11695-013-1156-z

ORIGINAL CONTRIBUTIONS

Does Tissue Ischemia Actually Contribute To Leak after Sleeve Gastrectomy? An Experimental Study Maria Natoudi & Dimitrios Theodorou & Apostolos Papalois & Panagiotis Drymousis & Leonidas Alevizos & Stylianos Katsaragakis & Georgios Zografos & Emmanouel Leandros & Evangelos Menenakos

Published online: 29 December 2013 # Springer Science+Business Media New York 2014

Abstract Background Staple line leak, although rare, is among the most common postoperative complications after sleeve gastrectomy (SG) and usually occurs in the gastroesophageal (GE) junction. Increased intragastric pressure, regional ischemia, and technical failure of stapling devices have been reported as the main risk factors of postoperative leak. The aim of this study was to evaluate the impact of ischemia and intraluminal pressure in leak appearance. Methods Landrace swine (n=12) were subjected to SG and total gastrectomy subsequently. Lactic acid, glycerol, and pyruvate were measured by microdialysis in GE junction and pylorus before and nine times after operation, and lactate/pyruvate (L/P) ratio was calculated as well. Moreover, ex vivo air was insufflated inside the tubularized stomach till a rupture of the staple line occurs. Maximum air pressure reached and location of rupture were recorded. Results Increase of lactic acid and L/P ratio were demonstrated in GE junction measurements; however, when the measurements between GE junction and pylorus were compared, no statistically significant differences were found, with the exception of a slightly increased lactate concentration in M. Natoudi : D. Theodorou : P. Drymousis : L. Alevizos : S. Katsaragakis : G. Zografos : E. Leandros : E. Menenakos First Department of Propaedeutic Surgery, Hippokration Hospital, Athens Medical School Greece, 114 Queen’s Sofia Avenue, Athens, Greece A. Papalois Experimental - Research Centre, ELPEN Pharmaceutical, 95 Marathonos Avenue, Pikermi, Athens, Greece L. Alevizos (*) Pipinou 52, 11251 Athens, Greece e-mail: [email protected] L. Alevizos e-mail: [email protected]

pylorus in the midst of measurements. The maximum air pressure recorded varied from 3 to 75 mmHg (mean 24.5 mmHg) and the majority of ruptures (n=8) occurred in GE junction. In one of them, clip displacement was noticed. Conclusions No evidence of increased ischemia in GE junction compared to pylorus was recorded. Increased intraluminal pressure and stapling malfunction may play the most important role in leak appearance. Keywords Sleeve gastrectomy . Staple line leak . Ischemia . Microdialysis . Intraluminal pressure

Introduction Obesity is a worldwide epidemic. Recent national data on obesity prevalence among adults, adolescents, and children in USA show that more than 33 % of adults and almost 17 % of children and adolescents are obese [1]. Based on the World Health Organization classification of obesity, it has been demonstrated that individuals in each obesity class are at increased risk of obesity-related illness as compared to those with a normal BMI (18.5–24.9 kg/m2) [2]. Surgical treatment remains the only evidence-based approach to achieve important and sustainable weight loss for patients with morbid obesity of classes II and III [3]. Sleeve gastrectomy (SG) is a relatively new option for the surgical management of morbid obesity [4] and it was originally published by Marceau et al. [5] in 1993 as a restrictive part of a duodenal switch malabsorptive operation (BPD-DS), in order to improve the results of billiopancreatic diversion without performing a distal gastrectomy. Later, laparoscopic sleeve gastrectomy (LSG) was recommended as the first-step in the treatment of super obese patients and in high-risk patients because of excessive comorbidity, as a bridge to a

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future more complicated bariatric operation such as BPD-DS or laparoscopic Roux-en-Y gastric bypass (LRYGBP) [6]. Analysis of the literature suggests that LSG can be a standalone procedure with comparable results to other bariatric operations, such as LRYGBP [7], and presents some respectable advantages including lack of an intestinal anastomosis, normal intestinal function which results to decreased need for a strict follow-up and supplemental vitamin or ion therapy, lack of internal hernias, no implantation of foreign body, and pylorus preservation which prevents dumping syndrome. In addition, it is considered a fast and easily reproduced procedure. Last but not least, the whole upper gastrointestinal tract remains accessible for endoscopic assessment [8]. Concerns remain, however, regarding postoperative complications. Minor surgical complications have an overall incidence of 11 % and major surgical complications of almost 5 % in large series [9]. The most common major complications associated with LSG are complications like bleeding or staple line gastric leak that lead to significant morbidity and even death [10]. Leaks, which usually cause the greatest morbidity, are classified into early, occurring during the first three postoperative days (POD), intermediate, noted between the fourth and seventh POD and late, occurring after the eighth POD. The area of greatest risk for the occurrence of leak after LSG is along the superior aspect of the staple line near the level of the crus of the diaphragm below the gastroesophageal (GE) junction. Leaks have been also classified according to their etiology into ischemic leaks and staple line failure leaks. However, many authors suggest that the major risk factor for gastric leak is not staple line dehiscence but ischemia in the gastric wall next to the staple line [11]. Classic ischemic fistulas secondary to ischemia usually appear when the staple line healing process is between the inflammation and fibrotic phase, while mechanical fistulas tend to occur during the first 28 h [12]. The aim of this study was to examine the microcirculation and the regional microenviroment of the formatted gastric tube after SG by microdialysis, which is considered a reliable monitoring method of tissue perfusion, in order to examine the role of ischemia in the formation of staple line leak after SG. Moreover, the “tubularized” stomach was insufflated with air in order to investigate the connection between increased intraluminal pressure, performance of stapling devices and staple line rupture.

Methods This was an experimental study. Twelve domestic pigs (Sus scrofa domesticus) of Landrace bread (mean weight 30.7 kg) were used. A 13th pig was excluded from the study due to technical failure. The study was performed in accordance with the guidelines of the Institutional Review Board and the

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Directive 86/609 of the European Union (no. of license for experimentation: 2991, May 2012). Moreover, the research protocol was adhered to the Guide for the Care and Use of Laboratory Animals [13], the Animal Welfare Act of 2006, and the principles on the accommodation and care of animals used for experimental and other scientific purposes presented in the “EUROGUIDE” by the Federation of European Laboratory Animal Science Associations in conjunction with the European Partnership for Alternative Approaches to Animal Testing [14]. Food was withheld 12 h before the procedure, while water access was given ad libitum. The experiment was acute and the animals were killed by 200 mg/kg pentobarbital sodium after the end of the procedure. The characteristics of the animal subjects used in this study are depicted in Table 1. Anesthesia and Monitoring Preparation All animals were premedicated with intramuscular injection of 15 mg/kg ketamine hydrochloride, 0.5 mg/kg midazolam, and 0.05 mg/kg atropine sulfate. The marginal auricular vein was catheterized, and anesthesia was induced with an intravenous bolus dose of 3 mg/kg propofol. They were then intubated with a 7.5 mm endotracheal tube. Animals were immobilized in the supine position on a surgical table. Additional 1 mg/kg propofol, 0.5 mg/kg cis-atracurium, and 4 μg/kg fentanyl were administered immediately prior to connecting the animals to a ventilator (Alpha Delta lung ventilator, Siare, Bologna, Italy). The mechanical ventilation was established with 15 ml/kgr of tidal volume and in 60 % oxygen concentration of the inspired gas mixture (60 % FiO2). During the procedure, the temperature of all animals was maintained at 38±1°C, using an electrically warmed blanket. Propofol infusion of 0.1 mg/kg/ min and additional doses of cis-atracurium at 20 μg/kg/min and fentanyl at 0.6 μg/kg/min were administered to maintain adequate anesthetic depth. Table 1 General characteristics and preoperative monitoring measurements of the animal subjects included in the study (mean values) Total n=12

Mean values

Range

Sex Male Female Weight Saturation (%) LCT

10 2 30.7 99.2 0.76

27–34 98–100 0.44–1.11

Blood pressure (diastolic/systolic) MAP Heart rate CVP

87.3/116.3 104.2 110.3 2.5

47–78/105–143 64–122 85–160 0–5

LCT lactate concentration in arterial blood, MAP mean arterial pressure, CVP central venous pressure

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After the intubation, a left neck incision was made to the swine and the left interior jugular vein and left exterior artery were cannulated for central vein access, invasive blood pressure monitoring and arterial blood gas sampling. Continuous electrocardiographic monitoring, a temperature sensor, and palmic oximetry set were attached to the chest wall, in the esophageal lumen, and to the pig's tail, respectively. Microdialysis Technique Microdialysis has been shown to be a safe and reproducible technique [15] which enables to monitor the composition of extracellular fluids in the living tissues by inserting the distal end of a double lumen catheter in the tissue to be monitored. The outer lumen of the catheter consists of a semipermeable membrane, which mimics a blood capillary. The proximal end of the probe end is connected to a pump, which extracts the microdialysate to a microvial for calculation of the concentration of the different molecules studied by the analyzer [16]. To date, microdialysis is becoming an established clinical technology that can be applied to most organs and has already many clinical implications including monitoring ischemia and reperfusion in vascular surgery, evaluating the effect of ischemia, trauma, and hemorrhage on brain cells, liver transplantation, sepsis, and myocardial metabolism [17, 18]. Moreover, microdialysis represents a very promising clinical tool in monitoring gastric ischemia [19]. Once cannulation of both the jugular vein and the carotid artery was achieved, the animals underwent midline laparotomy. After the insertion of a 38 Fr bougie, a microdialysis catheter (CMA-20; CMA/Microdialysis, Solna, Sweden) was placed 2 cm under the GE junction and a second microdialysis catheter was placed 3 cm proximal to the pylorus. Both catheters were placed under direct view in the submucosa of the anterior wall of the stomach close to the future staple line and secured by transfixing sutures (Fig. 1). During the insertion of the upper probe in one pig (the 13th), a big hematoma was created in the stomach wall. Measurements in this animal subject were also recorded, but it was excluded from the statistical analysis. Next, probes were perfused with normal saline solution at 0.2 μl/min using a microdialysis pump (CMA-107; CMA/ Microdialysis), and microvial collectors (CMA/Microdialysis). A 30-min period was used to collect the microdialysis samples, note as the baseline (time point 0). After the completion of SG, nine consecutive microdialysis samples from both catheters were collected for each animal subject (time points 1–9) for lactic acid, pyruvate, and glycerol concentration measurements using a CMA Microdialysis Analyzer (CMA/Microdialysis) to calculate the lactate/pyruvate (L/P) ratio. Each one of these nine measurements lasted for 30 min. Lactic acid and pyruvate were chosen as markers of adequate or insufficient oxygen delivery in the tissue and glycerol as marker of cell degeneration [20].

Fig. 1 Placement of the catheters in the anterior wall of the stomach close to the future staple line

All microdialysis samples were stored at −80°C for a maximum of 15 days. The samples were analyzed in one batch for each pig. Operative Technique After the baseline period all animal subjects underwent an open SG. – – – –



The pylorus was indentified and dissection of the greater omentum began 5 cm cephalad. The lesser sac was entered and all the branches of the gastroepiploic vessels were ligated at their point of entrance to the greater curvature. Dissection was performed until the gastric fundus was completely mobilized and the entire angle of His was visualized along with the left crura. The stomach was divided along the lesser curvature with the use of an Echelon stapling device. The Echelon compact linear cutter (60 mm) was used, loaded with ECR60D cartridges, which delivers six rows of stapling clips (Ethicon endo-surgery). A combination of Green reloads (4.1 mm) for the first firings and Blue reloads (3.5 mm) for the upper stomach were used. Stapling devices and cartridges are the same used in LSG. No staple line reinforcements or additional steps to strengthen of staple lines were done. After the end of the operation measurements of arterial blood pressure, mean arterial pressure, central venous pressure, heart rate, temperature, and microdialysis variables were obtained every 30 min to the end of the experiment.

Air Insufflation After the completion of all measurements, a total gastrectomy of the “sleeved” stomach was performed. The resected specimen was placed inside water, and it was insufflated with

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compressed air, through a Veress needle placed in the anterior wall, till the increased intragastric pressure leads to rupture of the staple line, which is detected by air bubbles along its surface (Fig. 2). Intragastric pressure at the time of rupture was recorded. Statistical Analysis Statistical analysis was performed using the SPSS 16.0 (SPSS®, Chicago, IL) statistical software. Quantitative data were expressed as either mean (±SD) or median and range. Differences were analyzed by Mann–Whitney U test and Wilcoxon test. Significance was tested at the 5 % level of statistical significance (p

Does tissue ischemia actually contribute to leak after sleeve gastrectomy? An experimental study.

Staple line leak, although rare, is among the most common postoperative complications after sleeve gastrectomy (SG) and usually occurs in the gastroes...
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