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Introduction: Although several studies report that the robotic approach is more costly than laparoscopy, the cost-effectiveness of robotic distal pancreatectomy (RDP) over laparoscopic distal pancreatectomy (LDP) is still an issue. This study evaluates the cost-effectiveness of the RDP and LDP approaches across several Spanish centres. Methods: This study is an observational, multicenter, national prospective study (ROBOCOSTES). For one year from 2022, all consecutive patients undergoing minimally invasive distal pancreatectomy were included, and clinical, QALY, and cost data were prospectively collected. The primary aim was to analyze the cost-effectiveness between RDP and LDP. Results: During the study period, 80 procedures from 14 Spanish centres were analyzed. LDP had a shorter operative time than the RDP approach (192.2 min vs 241.3 min, p = 0.004). RDP showed a lower conversion rate (19.5% vs 2.5%, p = 0.006) and a lower splenectomy rate (60% vs 26.5%, p = 0.004). A statistically significant difference was reported for the Comprehensive Complication Index between the two study groups, favouring the robotic approach (12.7 vs 6.1, p = 0.022). RDP was associated with increased operative costs of 1600 euros (p < 0.031), while overall cost expenses resulted in being 1070.92 Euros higher than the LDP but without a statistically significant difference (p = 0.064). The mean QALYs at 90 days after surgery for RDP (0.9534) were higher than those of LDP (0.8882) (p = 0.030). At a willingness-to-pay threshold of 20,000 and 30,000 euros, there was a 62.64% and 71.30% probability that RDP was more cost-effective than LDP, respectively. Conclusions: The RDP procedure in the Spanish healthcare system appears more cost-effective than the LDP. [ABSTRACT FROM AUTHOR]

Background: Laparoscopic postoperatives outcomes in adhesiolysis are promising but conversion and morbidity remains high. The objective of our study was to determine preoperative factors to individualize and select the most appropriate approach for each patient. Methods: Patients ≥18 years old undergoing emergent surgery for adhesive small bowel obstruction and internal hernias were evaluated. Bivariate and multivariate analysis were performed to investigate factors related to conversion to open surgery and to the type of adhesions. Results: Of 333 patients, 224 were operated by laparotomy and 109 by laparoscopy (conversion rate: 40%). Previous abdominal wall mesh, type of adhesions, bowel lesion, need for intestinal resection and laparoscopic skills were statistically related to conversion. In the multivariate analysis, complex adhesions (OR 4.3, 95% CI 1.5–12.2; P = 0.006), the need for intestinal resection (OR 14.16, 95% CI 2.55–78.68; P = 0.002), and non‐advanced laparoscopy surgeons (OR 4.31, 95% CI 1.56–11.94; P = 0.005) were independent factors for conversion to open surgery. ASA III–IV, previous surgeries, previous abdominal mesh and previous adhesiolysis were related to complex adhesions. Previous laparoscopic surgery and internal hernia or closed loop in computed tomography were associated with simple adhesions as a cause of the obstruction. In the multivariate, previous adhesiolysis (OR 4.76, 95% CI 1.23–18.3; P = 0.023) and the findings on computed tomography were significantly related with the type of adhesion. Conclusion: Some preoperative factors allow to individualize the surgical approach in the adhesive small bowel obstruction improving surgical outcomes. [ABSTRACT FROM AUTHOR]

Background: Genetic evaluation is essential in assessing colorectal cancer (CRC) and colorectal liver metastasis (CRLM). The aim of this study was to determine the pragmatic value of KRAS on oncological outcomes after CRLM according to the ESMO recommendations and to query whether it is necessary to request KRAS testing in each situation. Methods: A retrospective cohort of 126 patients who underwent surgery for hepatic resection for CRLM between 2009 and 2020 were reviewed. The patients were divided into three categories: wild-type KRAS, mutated KRAS and impractical KRAS according to their oncological variables. The impractical (not tested) KRAS group included patients with metachronous tumours and negative lymph nodes harvested. Disease-free survival (DFS), overall survival (OS) and hepatic recurrence-free survival (HRFS) were calculated by the Kaplan–Meier method, and a multivariable analysis was conducted using the Cox proportional hazards regression model. Results: Of the 108 patients identified, 35 cases had KRAS wild-type, 50 cases had a KRAS mutation and the remaining 23 were classified as impractical KRAS. Significantly longer medians for OS, HRFS and DFS were found in the impractical KRAS group. In the multivariable analyses, the KRAS mutational gene was the only variable that was maintained through OS, HRFS and DFS. For HRFS (HR: 13.63; 95% confidence interval (CI): 1.35–100.62; p = 0.010 for KRAS), for DFS (HR: 10.06; 95% CI: 2.40–42.17; p = 0.002 for KRAS) and for OS (HR: 4.55%; 95% CI: 1.37–15.10; p = 0.013). Conclusion: Our study considers the possibility of unnecessary KRAS testing in patients with metachronous tumours and negative lymph nodes harvested. Combining the genetic mutational profile (i.e., KRAS in specific cases) with tumour characteristics helps patient selection and achieves the best prognosis after CRLM resection. [ABSTRACT FROM AUTHOR]

Multiple attempts have been made to manage the pancreatic stump and the pancreatic duct in order to reduce the rate of postoperative pancreatic fistula (POPF) after pancreaticoduodenectomy (PD), however radiofrequency-based technologies could help to achieve this goal. Previous encouraging clinical and experimental results support the use of endoluminal thermal ablation (ETHA) of the main pancreatic duct to reduce pancreatic exocrine secretion and hence POPF. We here describe our initial clinical experience with ETHA of the main pancreatic duct in two cases at high risk of POPF. Two cases underwent PD for malignancy with a high risk of POPF (adenocarcinoma, obese patients, surgical difficulties with heavy intraoperative blood loss, soft pancreas or walled-off pancreatitis and a tight small pancreatic main duct). In both cases, ETHA of the main pancreatic duct was conducted intraoperatively just before Blumgart-type pancreatic-jejunal anastomosis using a ClosureFast catheter (Medtronic, Mansfield, MA, USA) normally used for varicose vein treatment (therefore an off-label use). Although a clear radiological POPF was detected in the second case, the clinical postoperative course in both cases was uneventful. Little pancreatic fluid collected in the abdominal drainage with low levels of amylase enzyme, confirming low exocrine pancreatic function. No other procedure-related complications were detected. Endoluminal thermal ablation of the main pancreatic duct may be a feasible and safe technique to reduce the adverse effects of POPF after PD. [ABSTRACT FROM AUTHOR]

To study the differences between continuous and short-pulse mode microwave ablation (MWA). We built a computational model for MWA including a 200 mm long and 14 G antenna from Amica-Gen and solved an electromagnetic-thermal coupled problem using COMSOL Multiphysics. We compared the coagulation zone (CZ) sizes created with pulsed and continuous modes under ex vivo and in vivo conditions. The model was used to compare long vs. short pulses, and 1000 W high-powered short pulses. Ex vivo experiments were conducted to validate the model. The computational models predicted the axial diameter of the CZ with an error of 2–3% and overestimated the transverse diameter by 9–11%. For short pulses, the ex vivo computer modeling results showed a trend toward larger CZ when duty cycles decreases. In general, short pulsed mode yielded higher CZ diameters and volumes than continuous mode, but the differences were not significant (<5%), as in terms of CZ sphericity. The same trends were observed in the simulations mimicking in vivo conditions. Both CZ diameter and sphericity were similar with short and long pulses. Short 1000 W pulses produced smaller sphericity and similar CZ sizes under in vivo and ex vivo conditions. The characteristics of the CZ created by continuous and pulsed MWA show no significant differences from ex vivo experiments and computer simulations. The proposed idea of enlarging coagulation zones and improving their sphericity in pulsed mode was not evident in this study. [ABSTRACT FROM AUTHOR]

Accurate assessment of the vascular anatomy is a prerequisite of any pancreatic resection, since an unnoticed arterial injury in the context of a complex resection such as Whipple procedure, can seriously jeopardize patient's safety. This article aims to describe an infrequent anatomic variant of a replaced right hepatic artery originating directly from the gastroduodenal artery and its potential implications for duodenopancreatectomy, as the gastroduodenal artery is routinely divided. We present here two different cases of this arterial abnormality identified during a Whipple procedure and its implications in each different setting. Preoperative identification of anatomical variations is essential for proficient surgical planning. Nevertheless, when detected during surgery, an meticulous dissection of the hepatoduodenal ligament is required to identify all the vascular relations in order to avoid irreversible damage. [ABSTRACT FROM AUTHOR]

Metastases in the liver frequently grow as scattered tumor nodules that neither can be removed by surgical resection nor focally ablated. Previously, we have proposed a novel technique based on irreversible electroporation that may be able to simultaneously treat all nodules in the liver while sparing healthy tissue. The proposed technique requires increasing the electrical conductivity of healthy liver by injecting a hypersaline solution through the portal vein. Aiming to assess the capability of increasing the global conductivity of the liver by means of hypersaline fluids, here, it is presented amathematical model that estimates the NaCl distributionwithin the liver and the resulting conductivity change. The model fuses well-established compartmental pharmacokinetic models of the organ with saline injection models used for resuscitation treatments, and it considers changes in sinusoidal blood viscosity because of the hypertonicity of the solution. Here, it is also described a pilot experimental study in pigs in which different volumes of NaCl 20% (from 100 to 200 mL) were injected through the portal vein at different flow rates (from 53 to 171 mL/minute). The in vivo conductivity results fit those obtained by the model, both quantitatively and qualitatively, being able to predict the maximum conductivity with a 14.6% average relative error. The maximum conductivity value was 0.44 second/m, which corresponds to increasing 4 times the mean basal conductivity (0.11 second/m). The results suggest that the presented model is well suited for predicting on liver conductivity changes during hypertonic saline injection [ABSTRACT FROM AUTHOR]

Background. Spread hepatic tumours are not suitable for treatment either by surgery or conventional ablation methods. The aim of this study was to evaluate feasibility and safety of selectively increasing the healthy hepatic conductivity by the hypersaline infusion (HI) through the portal vein. We hypothesize this will allow simultaneous safe treatment of all nodules by irreversible electroporation (IRE) when applied in a transhepatic fashion. Material and methods. Sprague Dawley (Group A, n = 10) and Athymic rats with implanted hepatic tumour (Group B, n = 8) were employed. HI was performed (NaCl 20%, 3.8 mL/Kg) by trans-splenic puncture. Deionized serum (40 mL/Kg) and furosemide (2 mL/Kg) were simultaneously infused through the jugular vein to compensate hypernatremia. Changes in conductivity were monitored in the hepatic and tumour tissue. The period in which hepatic conductivity was higher than tumour conductivity was defined as the therapeutic window (TW). Animals were monitored during 1-month follow-up. The animals were sacrificed and selective samples were used for histological analysis. Results. The overall survival rate was 82.4% after the HI protocol. The mean maximum hepatic conductivity after HI was 2.7 and 3.5 times higher than the baseline value, in group A and B, respectively. The mean maximum hepatic conductivity after HI was 1.4 times higher than tumour tissue in group B creating a TW to implement selective IRE. Conclusions. HI through the portal vein is safe when the hypersaline overload is compensated with deionized serum and it may provide a TW for focused IRE treatment on tumour nodules. [ABSTRACT FROM AUTHOR]

Background: Laparoscopic pancreaticoduodenectomy (LPD) is a complex procedure that is becoming increasingly popular among surgeons. Postoperative pancreatic fistula (POPF) remains the most feared specific complication in reconstruction after PD. The Blumgart anastomosis (BA) has been established as one of the safest anastomosis for pancreas remnant reconstruction, with low rates of POPF and postoperative complications. The procedure for performing this anastomosis by laparoscopic approach has not been reported to date. Methods: We describe our technique of LPD with laparoscopic-adapted BA (LapBA) and present the results obtained. A case-matched analysis with open cases of BA is also reported. Results: Since February 2013 to February 2016, thirteen patients were operated of LapBA. An equivalent cohort of open PD patients was obtained by matching sex, ASA, pancreas consistency and main pancreatic duct diameter. Severe complications (grades III-IV) and length of stay were significantly lesser in LapBA group. No differences in POPF, readmission, reoperation rate and mortality were detected. Conclusions: The LapBA technique we propose can facilitate the pancreatic reconstruction after LPD. In this case-matched study, LPD shows superior results than open PD in terms of less severe postoperative complications and shorter length of stay. Randomized control trials are required to confirm these results. [ABSTRACT FROM AUTHOR]

Bipolar radiofrequency (RF) ablation, especially with perfusion of saline, has been shown to increase volume over monopolar conventional methods. The aims of this study are to study whether this method is linked to too flattened thermal lesions and premature rise of impedance and to elucidate some safety concerns. Eighteen RF ablations were performed using a 1.8-mm-diameter bipolar applicator in the liver of nine healthy pigs through laparotomy with or without temporary vascular occlusion [the Pringle maneuver (PGM)]: group A (n=9), without PGM; group B (n=9), with PGM. Hypertonic saline solutions (3% and 20 %) were injected through the applicator at a rate of 400 ml/h during the procedure. The pigs were followed up and they were euthanased on the 15th day. Impedance, current, power output, energy output, temperatures, diameters of thermal lesion, volume, sphericity ratio of thermal lesion were correlated among groups. Impedance at the end of the procedure (50.00 Omega+/-28.39 and 52.88 Omega+/-26.77, for groups A and B, respectively) was very similar to the starting impedance (50 Omega). In a median of 1 (range, 0-6) time per RF ablation procedure a reduction of 30 W from the selected power supply was observed during the RF ablation procedure linked to a slight increase of impedance. Volume and short diameter of thermal lesion were 21.28 cm3+/-11.78 and 2.85 cm+/-0.87 for group A, 87.51 cm3+/-25.20 and 4.31 cm+/-0.65 for group B. Continuous thermal between both electrodes were described with a global sphericity ratio of 1.91. One major complication (thermal injury to the stomach) was encountered in a case of cross-sectional necrosis of the targeted liver and attributed to heat diffusion after the procedure. This method has been shown to determine: (1) the relative control of impedance during the procedure; (2) ovoid and relatively large thermal lesions with less dependence upon closest vessels. [ABSTRACT FROM AUTHOR]

Purpose:To develop computer models to mimic the impedance-controlled pulsing protocol implemented in radiofrequency (RF) generators used for clinical practice of radiofrequency ablation (RFA), and to assess the appropriateness of the models by comparing the computer results with those obtained in previous experimental studies. Methods:A 12-min RFA was modelled using a cooled electrode (17G, 3 cm tip) inserted in hepatic tissue. The short (transverse) diameter of the coagulation zone was assessed underin vivo(with blood perfusion (BP) and considering clamping) andex vivo(at 21 °C) conditions. The computer results obtained by programming voltage pulses were compared with current pulses. Results:The differences between voltage and current pulses were noticeable: using current instead of voltage allows larger coagulation zones to be created, due to the higher energy applied by current pulses. If voltage pulses are employed the model can accurately predict the number of roll-offs, although the waveform of the applied power is clearly not realistic. If current voltages are employed, the applied power waveform matches well with those reported experimentally, but there are significantly fewer roll-offs. Our computer results were overall into the ranges of experimental ones. Conclusions:The proposed models reproduce reasonably well the electrical-thermal performance and coagulation zone size obtained during an impedance-controlled pulsing protocol. [ABSTRACT FROM PUBLISHER]

Purpose: The aim of this study was to assess the capacity of two methods of surgical pancreatic stump closure in terms of reducing the risk of pancreatic fistula formation (POPF): radiofrequency-induced heating versus mechanical stapler.Materials and methods: Sixteen pigs underwent a laparoscopic transection of the neck of the pancreas. Pancreatic anastomosis was always avoided in order to work with an experimental model prone to POPF. Pancreatic stump closure was conducted either by stapler (ST group,n = 8) or radiofrequency energy (RF group,n = 8). Both groups were compared for incidence of POPF and histopathological alterations of the pancreatic remnant.Results: Six animals (75%) in the ST group and one (14%) in the RF group were diagnosed with POPF (p = 0.019). One animal in the RF group and three animals in the ST group had a pseudocyst in close contact with both pancreas stumps. On day 30 post-operation (PO), almost complete atrophy of the exocrine distal pancreas was observed when the main pancreatic duct was efficiently sealed.Conclusions: Our findings suggest that RF-induced heating is more effective at closing the pancreatic stump than mechanical stapler and leads to the complete atrophy of the distal remnant pancreas. [ABSTRACT FROM AUTHOR]

Background: Laparoscopic distal pancreatectomy (LDP) for large pancreatic tumors may require prolonged dissection, and this could be associated with increased operative time and intraoperative complications. Methods: From a total cohort of 190 consecutive patients undergoing LDP, 18 patients were found to have pancreatic tumors >5 cm and were included in the retrospective study of prospectively collected data. Three techniques were used to approach the splenic vessels: the superior pancreatic, the inferior supracolic and post-pancreatic transection. Results: Of these 18 patients, 13 were women and 5 were men, the median age was 68 years and their median tumor size 7 cm. Exocrine pancreatic malignancy was diagnosed in 8 patients, 6 patients had neuroendocrine pancreatic tumors and 4 patients cystic neoplasm. The median number of resected nodes was 14. R 1 resections for exocrine pancreatic malignancies were found in 50% of patients. Morbidity (grade >II) was found in 16.6% of patients and 30 days mortality in 1 patient. Overall median survival was 50 months and 29 months for patients with exocrine pancreatic malignancies. Conclusions: LDP for large tumors, while technically demanding, is possible without additional morbidity and did not compromise short- and longterm oncological outcomes. [ABSTRACT FROM AUTHOR]

Background Pancreatic duct ligation (PDL) has been used as a model of chronic pancreatitis and as a model to increase β-cell mass. However, studies in mice have demonstrated acinar regeneration after PDL, questioning the long-term validity of the model. We aim to elucidate whether RF-assisted transection (RFAT) of the main pancreatic duct is a reliable PDL model, both in short (ST, 1-month) and long-term (LT, 6-months) follow-ups. Methods Eleven pigs were subjected to RFAT. Biochemical (serum/peripancreatic amylase and glucose) and histological changes (including a semiautomatic morphometric study of over 1000 images/pancreas and IHC analysis) were evaluated after ST or LT follow-up and also in fresh pancreas specimens that were used as controls for 1 (n = 4) and 6 months (n = 6). Results The distal pancreas in the ST was characterized by areas of acinar-to-ductal metaplasia (56%) which were significantly reduced at LT (21%) by fibrotic replacement and adipose tissue. The endocrine mass showed a normal increase. Conclusion RFAT in the pig seems to be an appropriate PDL model without restoration of pancreatic drainage or reduction of endocrine mass. [ABSTRACT FROM AUTHOR]

Introduction: Laparoscopic distal pancreatectomy (LDP) is replacing open surgery as the technique of choice for benign and premalignant lesions of the left pancreas. In most laparoscopic series, the supine decubitus or semilateral position is preferred. A posterior approach with the patient in full right lateral decubitus (PA-FRLD) has been proposed as an alternative. Patients and Methods: From July 2012 to November 2014 we performed 14 LDPs. PA-FRLD was chosen in 8 patients; in 6 patients splenectomy was also performed. Results: Definitive diagnoses were 3 cases of pancreatic ductal adenocarcinoma, 2 cases of nonfunctioning neuroendocrine tumors, 1 case of bulky serous cystic neoplasm, 1 case of inflammatory chronic pancreatitis, and 1 case of pancreatic trauma (duct disruption). No conversions were required. No postoperative pancreatic fistula was detected. No patient required transfusion. Two patients had Clavien II and IIIb postoperative complications. In both cases in which preservation of the splenic vessels was attempted, it was successfully achieved. Conclusions: The PA-FRLD position is a valid alternative to the supine or semilateral position for LDP. This approach is especially beneficial for resection of complex and bulky lesions of the tail of the pancreas and those in close contact with retroperitoneal organs and can also facilitate spleen-preserving LDP. [ABSTRACT FROM AUTHOR]

Open necrosectomy, the standard surgical treatment of infected pancreatic necrosis (IPN), presents a high rate of postoperative complications and an associated mortality of 20-60%. In the last decade various minimally invasive approaches (MIA) have been proposed for the treatment of IPN and the results seem to improve on those reported with open necrosectomy. These MIA include: percutaneous, retroperitoneal, endoscopic (endoluminal) and laparoscopic (transperitoneal). The adoption of the step-up approach in the management of severe acute pancreatitis (SAP) facilitates the implementation of MIA as the surgical treatment of choice in most cases. Since MIA require the expertise of radiologists, endoscopists and surgeons, patients suffering SAP should be treated by multidisciplinary teams in referral centers. We describe the MIA currently available and discuss their advantages, disadvantages, and results. [ABSTRACT FROM AUTHOR]

Purpose: To assess by means of computer simulations whether the heat sink effect inside a large vessel (portal vein) could protect the vessel wall from thermal damage close to an internally cooled electrode during radiofrequency (RF)-assisted resection. Methods: First, in vivo experiments were conducted to validate the computational model by comparing the experimental and computational thermal lesion shapes created around the vessels. Computer simulations were then carried out to study the effect of different factors such as device-tissue contact, vessel position, and vessel-device distance on temperature distributions and thermal lesion shapes near a large vessel, specifically the portal vein. Results: The geometries of thermal lesions around the vessels in the in vivo experiments were in agreement with the computer results. The thermal lesion shape created around the portal vein was significantly modified by the heat sink effect in all the cases considered. Thermal damage to the portal vein wall was inversely related to the vessel-device distance. It was also more pronounced when the device-tissue contact surface was reduced or when the vessel was parallel to the device or perpendicular to its distal end (blade zone), the vessel wall being damaged at distances less than 4.25 mm. Conclusions: The computational findings suggest that the heat sink effect could protect the portal vein wall for distances equal to or greater than 5 mm, regardless of its position and distance with respect to the RF-based device. [ABSTRACT FROM AUTHOR]

Background: Postoperative pancreatic fistula (PPF) is the most frequent and serious complication after laparoscopic distal pancreatectomy (LDP). Our goal was to compare the performance, in terms of PPF prevention, and safety of a radiofrequency (RF)-assisted transection device versus a stapler device in a porcine LDP model. Methods: Thirty-two animals were randomly divided into two groups to perform LDP using a RF-assisted device (RF group; n = 16) and stapler device (ST group; n = 16) and necropsied 4 weeks after surgery. The primary endpoint was the incidence of PPF. Secondary endpoints were surgery/transection time, intra/postoperative complications/deaths, postoperative plasmatic amylase and glucose concentration, peritoneal liquid amylase and interleukin 6 (IL-6) concentrations, weight variations, and histopathological changes. Results: Two clinical and one biochemical PPF were observed in the ST and RF groups respectively. Peritoneal amylase concentration was significantly higher in the RF group 4 days after surgery, but this difference was no longer present at necropsy. Both groups presented a significant decrease in peritoneal IL-6 concentration during the postoperative follow-up, with no differences between the groups. RF group animals showed a higher postoperative weight gain. In the histopathological exam, all RF group animals showed a common pattern of central coagulative necrosis of the parenchymal surface, surrounded by a thick fibrosis, which sealed main and secondary pancreatic ducts and was not found in ST group. Conclusions: The fibrosis caused by an RF-assisted device can be at least as safe and effective as stapler compression to achieve pancreatic parenchyma sealing in a porcine LDP model. [ABSTRACT FROM AUTHOR]

Purpose: The aim of this study was to assess the feasibility of a hybrid ablative technique based on applying electroporation (EP) pulses just before conducting radiofrequency ablation (RFA). The rationale was that the EP-induced reduction in blood perfusion could be sufficient to reduce the thermal sink effect and hence to increase the coagulation volume in comparison to that created exclusively by RFA. Materials and methods: A modelling study and in vivo experimental study were used. A Cool-tip RF applicator was used both for EP and RFA. Results: Overall, the results did not show any synergy effect from using the hybrid technique. Applying EP pulses prior to RFA did not increase the coagulation zone obtained and the lesions were almost identical. Additional computer simulations provided an explanation for this; the effect of reducing blood perfusion by thermal damage during RFA completely masks the effect of reducing blood perfusion by EP. This is because both thermal damage and EP affect the same zone, i.e. the tissue around the electrode. Conclusions: Our computer modelling and in vivo experimental findings suggest that the combination of EP and RFA with monopolar applicators does not provide an additional benefit over the use of RFA alone. [ABSTRACT FROM AUTHOR]

Purpose: The Cool-tip electrode is one of the most widely employed applicators in radiofrequency (RF) hepatic ablation. Previous research demonstrated that it is possible to enlarge coagulation volume when the single cooled electrode is associated with distant infusion of saline (hybrid applicator). The aim of this study was to compare the electrical-thermal behaviour of the Cool-tip electrode with that of the hybrid applicator. Materials and methods: Forty-two RF ablations were performed on a total of 10 pigs: 22 with the Cool-tip electrode and 20 with the hybrid applicator (low infused saline volumetric flow rate of 6 mL/h at 2 mm distance). We compared both electrical performance (delivered power and number of roll-offs, i.e. sudden rises in impedance that interrupt the power delivery) and coagulation zone characteristics. In addition, we built a one-dimensional model to provide a basic physical explanation of the difference in performance between the different applicators. Results: The experimental results showed that the number of roll-offs with the Cool-tip electrode was higher (24.3 ± 3.1 versus 6.7 ± 7.0). The hybrid applicator created larger coagulation volumes (19.7 ± 9.5 cm3 versus 9.5 ± 5.8 cm3) with larger transverse diameters (2.5 ± 0.6 versus 1.9 ± 0.5 cm). The one-dimensional model confirmed the delay in the incidence of the first roll-off, but not the heterogeneity of the hybrid applicator's electrical performance in the experiments. Conclusions: The hybrid applicator produces fewer roll-off episodes than the Cool-tip electrode and creates larger coagulation volumes with larger transverse diameters. [ABSTRACT FROM AUTHOR]

Purpose: To study the capacity of an internally cooled radiofrequency (RF) bipolar applicator to create sufficiently deep thermal lesions in hepatic tissue. Materials and methods: Three complementary methodologies were employed to check the electrical and thermal behaviour of the applicator under test. The experimental studies were based on excised bovine ( ex vivo study) and porcine liver ( in vivo study) and the theoretical models were solved by means of the finite element method (FEM). Results: Experimental and computational results showed good agreement in terms of impedance progress and lesion depth (4 and 4.5 mm respectively for ex vivo conditions, and ≈7 and 9 mm respectively for in vivo conditions), although the lesion widths were overestimated by the computer simulations. This could have been due to the method used to assess the thermal lesions; the experimental lesions were assessed by the white coagulation zone, whereas the tissue damage function was used to assess the computational lesions. Conclusions: The experimental results suggest that this applicator could create in vivo lesions to a depth of around 7 mm. It was also observed that the thermal lesion is mainly confined to the area between both electrodes, which would allow lesion width to be controlled by selecting a specific applicator design. The comparison between the experimental and computational results suggests that the theoretical model could be usefully applied in further studies of the performance of this device. [ABSTRACT FROM AUTHOR]

Background and Aim: Despite technological improvements in pancreatic surgery, the incidence and morbidity of pancreatic leak after resection of distal pancreas are persistently high in most series. Laparoscopic distal pancreatectomy (LDP) is today the gold standard procedure for benign and certain malignant neoplasms of the pancreatic body and tail in specialized centers. This study evaluated safety and feasibility of a radiofrequency (RF)-assisted transection device in a porcine model of LDP. Materials and Methods: LDP was performed on 10 pigs (median weight, 39.6 kg) using a new device based on an internally cooled RF-assisted electrode (Coolinside®, Apeiron Medical, Valencia, Spain). The animals were subjected to daily observation and then sacrificed and necropsied at 4 weeks postoperatively. Primary end points were the development of postoperative pancreatic fistula using the Pancreatic Anastomotic Leak Study Group definition and/or the presence of abdominal amylase-rich fluid collections or abscesses during necropsy and pathological study and/or dye extravasation from the pancreatic remnant duct. Secondary end points were intra- or postoperative complications, surgery, and transection duration. Results: No clinically relevant postoperative pancreatic fistulas were observed. In one case a grade A postoperative fistula was diagnosed due to amylase drain concentration of more than 6200 IU/mL on postoperative day 4. Median peritoneal liquid amylase concentration on postoperative day 4 was 2399.0 IU/L (range, 819.2-7122.0 IU/L), similar to the median plasma amylase level of 1520.8 IU/L (range, 1015.3-4056.6 IU/L). Median surgery time was 93.5 minutes (range, 46.0-140.0 minutes), and median transection time was 4.5 minutes (range, 2.0-26.0 minutes). There was one postoperative wound infection. There were no postoperative deaths or major complications. During the histopathological study, the surgical margin of the remaining pancreas showed a common pattern with a central area of necrosis surrounded by granulomatous infiltrate and fibrosis. Ductal obliteration was observed. No purulent inflammatory infiltrate or abscesses were present. Conclusion: Experimental findings suggest that performing pancreatic transection with Coolinside in a animal model of LDP is feasible and safe. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate and numerically score histological alterations observed in the acute phase in the esophagus after being exposed to a hyperthermic dosage and subsequently to correlate the scores obtained with the hyperthermic treatment parameters (i.e. temperature (T) and time (t)). Material and methods: Esophagus samples obtained from New Zealand white rabbits were immersed in a temperature-controlled saline bath at 40, 50, 60 and 70°C for 30, 60 and 90 s. Samples were then processed for histological analysis (Masson Trichrome technique), and evaluated by searching for objective heat-damage signs. A numerical value was assigned to each sample for each finding. Results: In general, all the layers were affected by the treatment, however, the greatest alterations were found in the epithelium and deeper muscular layers (circular and longitudinal). We found no damage (i.e. no differences to control) in all of the samples treated at 40°C, and severe damage in treatments at 60 and 70°C, regardless of exposure time. On the other hand, samples treated at 50°C did show different results related to time: no damage for 30 s, light damage for 60 s, and moderate damage for 90 s. We assigned a score value to each hyperthermic dosage, and obtained the fitted equation based on a logarithmic transformation of the Arrhenius equation: Score = 130.7 - 40,851/(T + 273) + log t, (R2 = 0.9326, P < 0.0001). Conclusions: Hyperthermic treatment mainly affects the epithelium and deeper muscular layers. The results suggest a damage threshold of 50°C for treatments of 30-90 s. The proposed scoring system provides a good fit with the hyperthermic parameters. [ABSTRACT FROM AUTHOR]

Background: Efficient and safe transection of biological tissue in liver surgery is strongly dependent on the ability to address both parenchymal division and hemostasis simultaneously. In addition to the conventional clamp crushing or finger fracture methods other techniques based on radiofrequency (RF) currents have been extensively employed to reduce intraoperative blood loss. In this paper we present our broad research plan for a new RF-assisted device for bloodless, rapid resection of the liver. Methods: Our research plan includes computer modeling and in vivo studies. Computer modeling was based on the Finite Element Method (FEM) and allowed us to estimate the distribution of electrical power deposited in the tissue, along with assessing the effect of the characteristics of the device on the temperature profiles. Studies based on in vivo pig liver models provided a comparison of the performance of the new device with other techniques (saline-linked technology) currently employed in clinical practice. Finally, the plan includes a pilot clinical trial, in which both the new device and the accessory equipment are seen to comply with all safety requirements. Results: The FEM results showed a high electrical gradient around the tip of the blade, responsible for the maximal increase of temperature at that point, where temperature reached 100°C in only 3.85 s. Other hot points with lower temperatures were located at the proximal edge of the device. Additional simulations with an electrically insulated blade produced more uniform and larger lesions (assessed as the 55°C isotherm) than the electrically conducting blade. The in vivo study, in turn, showed greater transection speed (3 ± 0 and 3 ± 1 cm²/min for the new device in the open and laparoscopic approaches respectively) and also lower blood loss (70 ± 74 and 26 ± 34 mL) during transection of the liver, as compared to saline-linked technology (2 ± 1 cm²/min with P = 0.002, and 527 ± 273 mL with P = 0.001). Conclusion: A new RF-assisted device for bloodless, rapid liver resection was designed, built and tested. The results demonstrate the potential advantages of this device over others currently employed. [ABSTRACT FROM AUTHOR]

Background: Radiofrequency ablation (RFA) of tumors by means of internally cooled electrodes (ICE) combined with interstitial infusion of saline may improve clinical results. To date, infusion has been conducted through outlets placed on the surface of the cooled electrode. However, the effect of infusion at a distance from the electrode surface is unknown. Our aim was to assess the effect of perfusion distance (PD) on the coagulation geometry and deposited power during RFA using ICE. Methods: Experiments were performed on excised bovine livers. Perfusion distance (PD) was defined as the shortest distance between the infusion outlet and the surface of the ICE. We considered three values of PD: 0, 2 and 4 mm. Two sets of experiments were considered: 1) 15 ablations of 10 minutes (n ≥ 4 for each PD), in order to evaluate the effect of PD on volume and diameters of coagulation; and 2) 20 additional ablations of 20 minutes. The effect of PD on deposited power and relative frequency of uncontrolled impedance rises (roll-off) was evaluated using the results from the two sets of experiments (n ≥ 7 for each PD). Comparisons between PD were performed by analysis of variance or Kruskal-Wallis test. Additionally, non-linear regression models were performed to elucidate the best PD in terms of coagulation volume and diameter, and the occurrence of uncontrolled impedance rises. Results: The best-fit least square functions were always obtained with quadratic curves where volume and diameters of coagulation were maximum for a PD of 2 mm. A thirty per cent increase in volume coagulation was observed for this PD value compared to other values (P < 0.05). Likewise, the short coagulation diameter was nearly twenty five per cent larger for a 2 mm PD than for 0 mm. Regarding deposited power, the best-fit least square function was obtained by a quadratic curve with a 2 mm PD peak. This matched well with the higher relative frequency of uncontrolled impedance rises for PD of 0 and 4 mm. Conclusion: Saline perfusion at around 2 mm from the electrode surface while using an ICE in RFA improves deposition of energy and enlarges coagulation volume. [ABSTRACT FROM AUTHOR]

An amendment to this paper has been published and can be accessed via a link at the top of the paper. [ABSTRACT FROM AUTHOR]

Pancreatic duct ligation (PDL) in the murine model has been described as an exocrine pancreatic atrophy-inducing procedure. However, its influence has scarcely been described on premalignant lesions. This study describes the histological changes of premalignant lesions and the gene expression in a well-defined model of pancreatic ductal adenocarcinoma by PDL. Selective ligation of the splenic lobe of the pancreas was performed in Ptf1a-Cre(+/ki); K-ras LSLG12Vgeo(+/ki) mice (PDL-Kras mice). Three experimental groups were evaluated: PDL group, controls and shams. The presence and number of premalignant lesions (PanIN 1–3 and Atypical Flat Lesions—AFL) in proximal (PP) and distal (DP) pancreas were studied for each group over time. Microarray analysis was performed to find differentially expressed genes (DEG) between PP and PD. Clinical human specimens after pancreaticoduodenectomy with ductal occlusion were also evaluated. PDL-Kras mice showed an intense pattern of atrophy in DP which was shrunk to a minimal portion of tissue. Mice in control and sham groups had a 7 and 10-time increase respectively of risk of high-grade PanIN 2 and 3 and AFL in their DP than PDL-Kras mice. Furthermore, PDL-Kras mice had significantly less PanIN 1 and 2 and AFL lesions in DP compared to PP. We identified 38 DEGs comparing PP and PD. Among them, several mapped to protein secretion and digestion while others such as Nupr1 have been previously associated with PanIN and PDAC. PDL in Ptf1a-Cre(+/ki); K-ras LSLG12Vgeo(+/ki) mice induces a decrease in the presence of premalignant lesions in the ligated DP. This could be a potential line of research of interest in some cancerous risk patients. [ABSTRACT FROM AUTHOR]

The aim of this retrospective study was thus to evaluate postoperative morphological changes in the remnant pancreas after pancreaticoduodenectomy (PD) associated with postoperative pancreatic fistula (POPF). Fifty-one patients subjected to PD were enrolled in the study and allocated into 2 groups according to the presence (n = 16) or absence of POPF (n = 35). A morphological evaluation of the pancreas was conducted for up to a 20 months follow-up on CT scans and compared between groups. No significant differences were observed in morphology between the groups at the different preoperative and PO intervals, regardless of the clinical relevance of the POPF or POPF grade. However, in the overall patient analysis we observed a significant reduction of the entire pancreas over time. In fact, thickness decreased 0.4 mm/month, length 1.2 mm/month and volume 1.17 cm3/month over the PO. The impact of age, POPF, type of anastomosis, surgical technique and PO follow-up (time) was evaluated in a multivariate analysis using the general linear model, but only PO follow-up had a significant influence on the final model (p < 0.001). A significant reduction on pancreatic parenchyma (thickness, length and volume) occurs after PD with no significant differences between patients with or without POPF. [ABSTRACT FROM AUTHOR]

Radiofrequency energy has been used both experimentally and clinically to manage the pancreatic remnant after distal pancreatectomies. Our goal was to determine whether endoluminal radiofrequency (RF) ablation of the main pancreatic duct in large animals would be more efficient than glue occlusion as an exocrine pancreatic atrophy-inducing procedure. Thirty-four Landrace pigs were assigned to either the transpapilar (n = 16) or transection (n = 18) groups. The transection implied the pancreas neck was severed. In each of these groups the remaining distal pancreatic duct was occluded either by RF or by glue. In the transpapilar group complete atrophy was observed in all the RF cases, while atrophy was incomplete in all the members of the glue subgroup. The failure rate of the main pancreatic duct (usually expressed by a pseudocyst) in the transection groups was dramatically higher in the glue subgroup than the RF subgroups (9 out of 9 and 1 out of 9, respectively) and postoperative mortality occurred only in the glue subgroup (3 out of 9). These results show the superiority of endoluminal RF ablation over glue for main pancreatic duct occlusion, as seen by the degree of atrophy and fewer postoperative pancreatic fistulas. [ABSTRACT FROM AUTHOR]

Background: Laparoscopic pancreaticoduodenectomy (LPD) is a complex procedure that is becoming increasingly popular among surgeons. Postoperative pancreatic fistula (POPF) remains the most feared specific complication in reconstruction after PD. The Blumgart anastomosis (BA) has been established as one of the safest anastomosis for pancreas remnant reconstruction, with low rates of POPF and postoperative complications. The procedure for performing this anastomosis by laparoscopic approach has not been reported to date.Methods: We describe our technique of LPD with laparoscopic-adapted BA (LapBA) and present the results obtained. A case-matched analysis with open cases of BA is also reported.Results: Since February 2013 to February 2016, thirteen patients were operated of LapBA. An equivalent cohort of open PD patients was obtained by matching sex, ASA, pancreas consistency and main pancreatic duct diameter. Severe complications (grades III-IV) and length of stay were significantly lesser in LapBA group. No differences in POPF, readmission, reoperation rate and mortality were detected.Conclusions: The LapBA technique we propose can facilitate the pancreatic reconstruction after LPD. In this case-matched study, LPD shows superior results than open PD in terms of less severe postoperative complications and shorter length of stay. Randomized control trials are required to confirm these results. [ABSTRACT FROM AUTHOR]