Evren Durak

Tissue Response to Surgical Energy Devices

OBJECTIVES There is little data available on the effects of energy-based surgical devices (ESD) on tissues other than arteries and veins. As such, we quantified the lateral thermal damage associated with contemporary ESD: the Harmonic ACE, a prototype bipolar device known as the Gyrus Trisector, the Harmonic LCS-C5, and the LigaSure V. METHODS We divided 24 domestic pigs into 4 groups, 1 group for each ESD tested. Segments of bladder, stomach, small bowel, colon, ureter, peritoneum, arteries, and veins were exposed to each ESD. The tissues were stained with hematoxylin and eosin and evaluated by an experienced pathologist to quantitate the lateral energy spread associated with each device. We measured blade temperatures of each device using the IR-Flex thermal camera. RESULTS The Trisector developed the lowest mean blade temperature (97.84 degrees F), whereas the LigaSures was the second lowest (103.14 degrees F). The ACE and LCS-C5 created the highest blade temperatures, measuring 220.5 degrees F and 205.6 degrees F, respectively. The Trisectors mean full thickness and superficial lateral energy damage were 6.3 mm and 7.0 mm, respectively, whereas the Ligasures was 4.5 mm and 5.9 mm, respectively. For the ACE, however, mean full thickness and superficial energy spread were 2.4 mm and 2.8 mm, respectively, whereas the LCS-C5s were 3.1 mm and 4.3 mm, respectively. CONCLUSIONS The Harmonic ACE and LCS-C5 produced the least thermal damage in the tissues tested. ESD-associated tissue energy damage is not directly related to blade temperature, but is likely the result of several factors including blade temperature, transection time, tissue properties, and the vascularity of each transected tissue.

Incidence and management of enteric leaks after gastric bypass for morbid obesity during a 10-year period

BACKGROUND To describe the incidence, etiology, outcomes, and management of enteric leaks in patients who had undergone open or laparoscopic gastric bypass. METHODS From November 1996 to November 2006, 1133 patients underwent primary gastric bypass at Columbia University, New York-Presbyterian Hospital. A retrospective review of our prospective bariatric surgery registry identified 17 patients (1.5%) who developed a clinically apparent enteric leak after surgery. The demographic and outcome data were studied. RESULTS The mean body mass index was 52 kg/m(2) (range 35-65), and 15 (88%) of the 17 patients were women. The mean number of co-morbidities per patient was 1.3 and included hypertension in 11, diabetes in 9, and sleep apnea in 6. Ten patients had previously undergone abdominal surgery. The enteric leak was diagnosed by radiographic studies in 12 patients (9 of 12 by upper gastrointestinal series and 3 of 6 by computed tomography); the remaining 5 patients were diagnosed at re-exploration. Of the 17 patients, 12 (70%) were treated by laparoscopy and 5 (29%) by laparotomy. The mean time from completion of the index procedure to the diagnosis of the leak was 2 days (range 1-5) for patients treated by laparoscopy versus 4 days (range 1-6) for patients treated by laparotomy (P <.05). The patients treated by laparoscopy experienced a shorter hospital stay, but the difference was not statistically significant (mean 11.4 days, range 6-36, versus 18 days, range 7-33; P >.05). One of the laparoscopic patients (5.9%) died. CONCLUSION Enteric leak is a significant complication after gastric bypass. Prompt treatment should be based on clinical suspicion, because contrast and cross-sectional imaging studies might not be reliable diagnostic tests. A laparoscopic index procedure might be associated with an earlier diagnosis.

Risk factors associated with renal parenchymal fracture during laparoscopic cryoablation

To assess the risk factors for haemorrhage and renal fracture associated with renal cryoablation.

The utility of [11C] dihydrotetrabenazine positron emission tomography scanning in assessing β-cell performance after sleeve gastrectomy and duodenal-jejunal bypass

BACKGROUND The aim of this study was to evaluate the effect of sleeve gastrectomy (SG) and duodenal-jejunal bypass (DJB) on glucose homeostasis and to evaluate the utility of positron emission tomography (PET) scanning for assessing beta-cell mass. METHODS Goto-Kakizaki rats were divided into 4 groups: control, sham, SG, or DJB. Oral glucose tolerance, insulin, and glucagon-like peptide-1 (GLP-1) were measured before and after surgery. Before and 90 days after treatment, [(11)C] DTBZ micro PET scanning was performed. RESULTS The control and sham animals gained more weight compared with SG and DJB animals (P < or = .05). Compared with control animals, the glucose area under the curve was lower in DJB animals 30 and 45 days after operations (P < or = .05). At killing, GLP-1 levels were greater in the DJB group compared with sham and SG (P < or = .05), whereas insulin levels were greater in both DJB and SG compared with sham (P < or = .05). With PET scanning, the 90-day posttreatment mean vesicular monoamine transporter type 2 binding index was greatest in the DJB animals (2.45) compared with SG (1.17), both of which were greater than baseline control animals (0.81). CONCLUSION In type 2 diabetic rodents, DJB leads to improved glucose homeostasis and an increase in VMAT2 density as measured by PET scanning.

Evaluation of a protective laser sheath for application in flexible ureteroscopy.

OBJECTIVES Despite the obvious utility of the holmium laser, laser fibers frequently damage flexible ureteroscope components, such as the working channel, flexible component cable system, and fiber optical systems during routine ureteroscopic procedures. As such, we investigated the effects of the use of a flexible protective sheath on ureteroscope operation and its ability to protect ureteroscopes from laser fiber damage. METHODS The effects of insertion of the FlexGuard sheath into the working channel on endoscope deflection and irrigant flow rate were documented. Additionally, the force required to advance the laser fiber through a fully deflected endoscope, as well as the amount of laser energy required to penetrate the FlexGuard sheath, were assessed using two different ureteroscopes. RESULTS The FlexGuard sheath was easily inserted through the maximally deflected ureteroscopes. The presence of the laser sheath and a laser fiber in the working channel decreased the maximum deflection angle of the ureteroscopes by a mean of 7 degrees (from 73 degrees to 66 degrees). FlexGuard sheath insertion into the working channel also significantly diminished irrigant flow rates, from 0.55 mL/sec to 0.02 mL/sec, at an irrigation pressure of 100 cm H(2)O. The FlexGuard sheath reduced the amount of maximum force required to insert the laser fiber through each ureteroscope from 0.8 N to 0.2 N. The FlexGuard sheath was unable to protect the ureteroscope from laser energy damage. CONCLUSION The FlexGuard laser sheath significantly reduced the amount of force required to insert the laser fiber through the working channel. This reduction in force may have be protective against mechanical damage caused by laser fiber insertion. However, deployment of the sheath significantly diminished the rate of irrigant flow and the maximal deflection of the two ureteroscopes tested. Also, the sheath does not protect the ureteroscope from damage caused by laser energy. In each case the urologist will need to determine if the mechanical protective value of the sheath outweighs the negative impact on flow and deflection.

The effect of intraluminal content on the bursting strength of vessels ligated with the harmonic ACE and LigaSure V.

PURPOSE Energy-based surgical devices (ESDs) are critical for maintaining hemostasis during laparoscopy; however, there are no studies that have evaluated the function of ESDs under different physiologic conditions. We evaluated the effect of intraluminal vessel content on bursting pressure (BP) after ligation with two ESDs: the Harmonic ACE and the LigaSure V. MATERIALS AND METHODS Bursting trials were performed on the vasculature of 24 pigs. Blood vessels were distended with blood of different hematocrit concentrations or an albumin solution of varying protein content. The vessel size and BP of each vessel was recorded after ligation with each ESD. RESULTS In arteries 0 to 3 mm and veins 0 to 3 mm in size ligated with the Harmonic ACE or the LigaSure V, there were significantly elevated vessel BPs with supraphysiologic intraluminal hematocrits. In arteries and veins ligated with the Harmonic ACE, increasing albumin concentrations also led to increasing BPs, though these maximal BPs were lower than those obtained with supraphysiologic hematocrit levels. Increasing albumin concentrations did not increase the BP of the LigaSure V. Within the ranges tested, there was no decrease in vessel BP associated with anemia. CONCLUSION In small vessels, a supraphysiologic hematocrit increased the BP of both arteries and veins when using the Harmonic ACE or the LigaSure V. With the devices tested, anemia did not seem to affect BP. While factors such as intraluminal protein concentration may play a role with ultrasonic energy devices, the mechanism of the increased BP remains unclear. Better understanding of ESDs will help in the design of future devices.

A rodent model of metabolic surgery for study of type 2 diabetes and positron emission tomography scanning of beta cell mass

BACKGROUND Type 2 diabetes mellitus is a worldwide healthcare problem with major socioeconomic implications. Metabolic surgical procedures have been shown to improve diabetes, but the mechanism of action is poorly understood. The Goto-Kakizaki (GK) rodent is a type 2 diabetic animal model that is ideally situated for studying the effect of surgery on diabetes; however, the operative mortality is high. The aim of this study was to describe the operative technique, improvements in perioperative management, and the technique of micro-positron emission tomography (PET) scanning of the beta-cell mass in GK rodents. METHODS A total of 53 GK rats were divided into 1 of 3 operative groups: sham, sleeve gastrectomy, and duodenojejunal bypass. A subset of animals underwent micro-PET scanning with [11C]-dihydrotetrabenazine to determine the vesicular monoamine transporter 2 binding index, an indicator of beta-cell mass. RESULTS The 30-day mortality in the sham and sleeve gastrectomy rodents was 0; however, 2 sleeve gastrectomy rodents developed enterocutaneous fistula and 1 developed an abscess. In the duodenojejunal bypass group, the initial mortality rate was close to 90%; however, refinements in the surgical technique and perioperative management (fluids, antibiotics, pain control) lowered the mortality rate to 60%. The surgical technique is discussed in detail. [11C]-Dihydrotetrabenazine uptake in the pancreas was demonstrated on micro-PET scanning in the sham and duodenojejunal bypass rodents. CONCLUSION Intensive medical management in the perioperative period and attention to the operative technique lowered the mortality. [11C]-Dihydrotetrabenazine micro-PET scanning is a feasible method for assessing the beta-cell mass in GK rodents and could prove to be an important modality for evaluating beta-cell performance in type 2 diabetes.

Laparoscopic cholecystectomy in patients aged 80 years and older: an analysis of 111 patients.

Introduction: The incidence of cholelithiasis increases with age. More octogenarian (≥80 y) patients are undergoing laparoscopic cholecystectomy (LC) operation throughout the world. Patients and Methods: A retrospective study was conducted on patients older than 80 years (group 1: 111 patients) and those in the 18 to 79 years age group (group 2: 185 patients), who underwent LC between July 2005 and October 2009. The variables analyzed were the presentation, demographics, comorbid illnesses, American Society of Anaesthesiology (ASA) scores, history of previous abdominal surgery, the operative time, postoperative morbidity and mortality, and the length of hospital stay. A comparison was made between the two groups. Data was evaluated by using the &khgr;2 and the Fisher exact test. P<0.005 was considered significant. Results: The difference in both groups in the mean age and ASA scores were significant. The indication for LC was gallstone disease in 87 (78.4%) patients, acute cholecystitis in 16 (14.4%), and gallstone pancreatitis in 8 (7.2%) of group 1 patients. The conversion rate was not statistically significant. The mean operative time was 77 minutes in group 1 patients, and this was significantly longer than that of group 2 patients. The postoperative oral intake within 24 hours of surgery was significantly earlier in group 2 patients. Other parameters were not significantly different between the 2 groups. Conclusions: LC in octogenarians is a relatively safe procedure that can be performed with low morbidity and mortality rates. The comorbidities and higher ASA scale are major risk factors for postoperative complications in this age group of patients.

The effect of argon gas pressure on ice ball size and rate of formation.

INTRODUCTION Contemporary cryoablation technology utilizes the Joule-Thomson effect, defined as a change in temperature that results from expansion of a nonideal gas through an orifice or other restriction. We evaluated the effect of initial gas tank pressures on freezing dynamics in a single-probe model and in a multiprobe model using contemporary cryoablation technology. MATERIALS AND METHODS Cryoablation trials were performed in a standardized system of transparent gelatin molds at 25°C. Two sets of trials were performed. The first trial evaluated temperature and ice ball size for a given tank pressure when a single needle was deployed. The second trial recorded ice ball temperatures for each probe when multiple probes were fired simultaneously. RESULTS Trial 1: The rate of temperature change is directly related to the initial pressure of the gas being released, and the group with the highest starting pressures reached the lowest mean temperature and had the largest mean ice ball size (p < 0.01). Trail 2: Multiple-probe ablation did not affect the rate of temperature change or final temperature compared with firing a single probe (p > 0.7). CONCLUSIONS In accordance with the Joule-Thomson effect, higher initial gas pressures used for cryoablation in a transparent gel model demonstrate statistically significant lower temperatures, faster decreases in temperature, and formation of larger ice balls than lower gas pressures do. With contemporary technology, multiple simultaneous cryoprobe deployment does not compromise individual probe efficacy. The use of higher initial tank pressures will theoretically help future cryoprobes be more effective, creating a greater volume of cell necrosis and a smaller indeterminate zone.

Fistulojejunostomy in the Management of Chronic External Biliary Fistula

Aim: We have recently used an alternative surgical method to resolve external chronic refractory biliary fistula (ECRBF) and in this article we described our experience with external chronic refractory biliary fistula. Methods: We reviewed the records of patients who underwent ECRBF between 2000 and 2009. Since conservative or endoscopic management methods were not useful, fistulojejunostomy was the treatment of choice for these patients. Patients’ demographics, operation details, clinical and pathological findings and follow up data were retrieved. Results: We identified 12 patients (7 were female and 5 male, with a mean age of 47 years; range, 33 to 64 years) who had external chronic refractory biliary fistulas managed by fistulojejunostomy. All patients were admitted with obvious external bile fistulas with an average duration of 24 weeks (range 20 to 36 weeks). The fistulas were confirmed by PTC fistulography, ERCP and also MRCP in all patients. The fistulas occurred following cholecystectomy and bile duct exploration in 5 patients, liver hydatic surgery in 3, choledochojejunostomy anastomotic leak after Whipple procedure in 2 and liver trauma in 2 patients. The mean fistula output was measured as 573 cc per day. Follow up time is 49 weeks average. Conclusions: In this report we described our experience with fistulojejunostomy in the treatment of external chronic refractory biliary fistula when conventional surgical and minimal invasive approaches fail. Fistulojejunostomy can be considered as a viable alternative for the patients with external chronic refractory biliary fistula in those cases not amenable for conventional surgical or mininvasive procedures.