Optimal ablation volumes are achieved at submaximal power settings in a 2.45-GHz microwave ablation system.

INTRODUCTION: Local ablative therapies, including microwave ablation (MWA), are common treatment modalities for in situ tumor destruction. Currently, 2.45-GHz ablation systems are gaining prominence because of the shorter application times required. The aims of this study were to determine optimal power and time to ablation volume (AbV) ratios for a new 1.8-mm-2.45-GHz antenna using ex vivo tissue models. METHODS: The 1.8-mm-2.45-GHz Accu2i MWA system was employed to perform ablations in bovine liver, porcine muscle, and porcine kidney ex vivo. Whole tissues were prewarmed (35°C) and multiple ablations performed at power settings of 60 to 180 W for 2- to 6-minute time intervals. Postablation, tissues were dissected, AbVs calculated, and correlations to power and time settings made. RESULTS: Significant increases in AbV were measured between each of the time points for a constant power setting in all 3 tissues. Increasing power settings led to significant increases in AbV at power settings ≤140 W. However, no significant increase in AbV was obtained at power settings >140 W. CONCLUSIONS: Optimal efficiency for MWA using a new 1.8-mm-2.45-GHz system is achieved at settings of ≤140 W for 6 minutes in a range of ex vivo tissue and no additional benefit occurs by increasing the power setting to 180 W in these tissues.

Microwave ablation for hepatic malignancies: a multiinstitutional analysis.

OBJECTIVE: This study hypothesized that tumor size, number of tumors, surgical approach, and tumor histology significantly affected microwave ablation (MWA) success and recurrence-free survival. BACKGROUND: Although many hepatobiliary centers have adopted MWA, the factors that influence local control are not well described. METHODS: Consecutive patients with hepatic malignancy treated by MWA were included from 4 high-volume institutions (2003-2011) and grouped by histology: hepatocellular carcinoma (HCC), colorectal liver metastases, neuroendocrine liver metastases, and other cancers. Independent significance of outcome variables was established with logistic regression and Cox proportional hazards models. RESULTS: Four hundred fifty patients were treated with 473 procedures (139 HCC, 198 colorectal liver metastases, 61 neuroendocrine liver metastases, and 75 other) for a total of 875 tumors. Median follow-up was 18 months. Concurrent hepatectomy was performed in 178 patients (38%), and when performed was associated with greater morbidity. Complete ablation was confirmed for 839 of 865 tumors (97.0%) on follow-up cross-sectional imaging (10 were unevaluable). A surgical approach (open, laparoscopic, or percutaneous) had no significant impact on complication rates, recurrence, or survival. The local recurrence rate was 6.0% overall and was highest for HCC (10.1%, P = 0.045) and percutaneously treated lesions (14.1%, P = 0.014). In adjusted models, tumor size 3 cm or more predicted poorer recurrence-free survival (hazard ratio: 1.60, 95% CI: 1.02-2.50, P = 0.039). CONCLUSIONS: In this large data set, patients with 3 cm or more tumors showed a propensity for early recurrence, regardless of histology. Higher rates of local recurrence were noted in HCC patients, which may reflect underlying liver disease. There were no significant differences in morbidity or survival based on the surgical approach; however, local recurrence rates were highest for percutaneously ablated tumors.

Comparison of culture and molecular techniques for microbial community characterization in infected necrotizing pancreatitis.

BACKGROUND: Infected necrotizing pancreatitis is associated with significant morbidity and mortality. Peripancreatic fluid cultures may fail to identify all the infecting organisms. The aim of this study was to compare the bacterial biome of peripancreatic fluid from infected necrotizing pancreatitis patients using 16S ribosomal RNA (rRNA) DNA deep sequencing and quantitative polymerase chain reaction (qPCR) targeting the 16S rRNA gene versus standard laboratory culture. MATERIALS AND METHODS: Peripancreatic fluid was collected during operative or radiologic intervention and samples sent for culture. In parallel, microbial DNA was extracted, qPCR targeting the 16S rRNA gene and 16S rRNA PCR amplification followed by Illumina deep sequencing were performed. RESULTS: Using culture techniques, the bacterial strains most frequently identified were gram-negative rods (Escherichia coli, Klebsiella pneumoniae) and Enterococcus. Samples in which culture results were negative had copy numbers of the 16S rRNA gene close to background in qPCR analysis. For samples with high bacterial load, sequencing results were in some cases in good agreement with culture data, whereas in others there were disagreements, likely due to differences in taxonomic classification, cultivability, and differing susceptibility to background contamination. Sequencing results appeared generally unreliable in cases of negative culture where little microbial DNA was input into qPCR sequencing reactions. CONCLUSIONS: Both sequencing and culture data display their own sources of bias and potential error. Consideration of data from multiple techniques will yield a more accurate view of bacterial infections than can be achieved by any single technique.

Fibrin sealants and topical agents in hepatobiliary and pancreatic surgery: a critical appraisal.

INTRODUCTION: Fibrin sealants and topical hemostatic agents have been used extensively in hepatobiliary and pancreatic (HPB) surgery to promote coagulation and clot formation decreasing the need for allogeneic blood transfusion and to act as tissue sealants, ideally preventing biliary, enteric, and pancreatic leaks. RESULTS: Current literature has demonstrated some favorable outcomes using many different products for application in the field of HPB surgery. However, critical findings exist demonstrating lack of reproducible efficacy or benefit. In all, many clinical trials have demonstrated effectiveness of fibrin sealants and other agents at reducing the need for intraoperative and postoperative blood transfusion. Ability to effectively seal tissues providing biliostatic effect or preventing postoperative fistula formation remains debated as definitive evidence is lacking. CONCLUSIONS: In the following invited review, we discuss current literature describing the use of topical agents and fibrin sealants in liver and pancreas surgery. We summarize major contemporary clinical trials and their findings regarding the use of these agents in HPB surgery and provide evidence from the preclinical literature as to the translation of these products into the clinical arena.

Altered lysophosphatidic acid (LPA) receptor expression during hepatic regeneration in a mouse model of partial hepatectomy.

BACKGROUND: Hepatic regeneration requires coordinated signal transduction for efficient restoration of functional liver mass. This study sought to determine changes in lysophosphatidic acid (LPA) and LPA receptor (LPAR) 1-6 expression in regenerating liver following two-thirds partial hepatectomy (PHx). METHODS: Liver tissue and blood were collected from male C57BL/6 mice following PHx. Circulating LPA was measured by enzyme-linked immunosorbent assay (ELISA) and hepatic LPAR mRNA and protein expression were determined. RESULTS: Circulating LPA increased 72 h after PHx and remained significantly elevated for up to 7 days post-PHx. Analysis of LPAR expression after PHx demonstrated significant increases in LPAR1, LPAR3 and LPAR6 mRNA and protein in a time-dependent manner for up to 7 days post-PHx. Conversely, LPAR2, LPAR4 and LPAR5 mRNA were barely detected in normal liver and did not significantly change after PHx. Changes in LPAR1 expression were confined to non-parenchymal cells following PHx. CONCLUSIONS: Liver regeneration following PHx is associated with significant changes in circulating LPA and hepatic LPAR1, LPAR3 and LPAR6 expression in a time- and cell-dependent manner. Furthermore, changes in LPA-LPAR post-PHx occur after the first round of hepatocyte division is complete.

Adrenocortical carcinoma with intracaval extension to the right atrium: resection on cardiopulmonary bypass.

CASE PRESENTATION: A 28-year-old woman presented with dyspnea on exertion and elevated testosterone level. A 21 × 19 cm right adrenal mass was found invading the liver and inferior vena cava (IVC); tumor thrombus extended to the right atrium on transthoracic echocardiogram. OPERATIVE PROCEDURE: Median sternotomy and extended right subcostal incisions were made. Inferior surface of liver was mobilized and vessels to the tumor divided and packed. The IVC was isolated and cardiopulmonary bypass initiated. Tumor was excised from IVC and tumor thrombus extracted. After partial IVC wall resection, the venotomy was closed. The right atrium was explored for remaining thrombus. Segment 7 of the liver was resected with division of right hepatic vein. The patient was removed from bypass, and the cut surface of liver was reinforced with chromic sutures. Intraoperative ultrasound demonstrated no remaining tumor thrombus. Provisional closure was achieved with wound vac, and the next day, the patient's wound was closed primarily. OUTCOME: On postoperative day 3, the patient was extubated; she was discharged on day 12. Pathology revealed well-differentiated adenocarcinoma weighing 2.3 kg with negative surgical margins. Two months after surgery, she received radiation for suspected lumbar vertebral metastasis and initiated mitotane therapy. Follow-up surveillance scans showed no evidence of disease. DISCUSSION: Adrenocortical carcinoma is a rare malignancy presenting frequently in advanced stage with poor prognosis. Chemotherapy is often only moderately effective, while complete surgical resection is potentially curative. In this patient, excellent short-term outcome was achieved through radical surgical resection. We continue to monitor her closely for evidence of recurrence.

Robotic hepatobiliary and pancreatic surgery: lessons learned and predictors for conversion.

BACKGROUND: The use of surgical robots has slowly gained an increasing presence in the realm of hepatobiliary and pancreatic (HPB) surgery. With additional experience, anecdotal evidence has been useful in guiding patient selection for complex robotic procedures. In the following analysis, we reviewed our case series and looked for predictors of conversion in robotic HPB surgery. METHODS: We retrospectively reviewed all patients who underwent robotic HPB procedures by a single surgeon at two institutions during March 2006-June 2012. Patient demographics, operative data, procedure type and conversion information were recorded. Trends were analysed for indications for conversion. A subset analysis of robotic-assisted laparoscopic distal pancreatomy was performed and compared with laparoscopic and open distal pancreatectomy during the same time period by the same surgeon. RESULTS: During this time period, 77 patients underwent robotic hepatobiliary and pancreatic procedures. All procedures were performed by a single surgeon (J.M.) and included 38 males (49%) and 39 females (51%). Median age was 59 and the majority of patients were ASA class III. There were 24 conversions, which decreased in frequency from 2009 (7) to 2011 (3). Reasons for conversion included significant obesity and technical difficulty. Patients with conversions had more intraoperative blood loss (966 vs 176 ml), more frequently received transfusion (29% vs 2%) and were more likely to have postoperative intensive care. Overall length of stay was longer following conversion (8.3 vs 5.6 days). CONCLUSIONS: Robotic-assisted hepatobiliary and pancreatic procedures are often extremely complex, with a significant learning curve. Recognizing factors that prohibit successful completion of a robotic-assisted surgical procedure is key for patient safety. Careful patient selection in the appropriate settings facilitates the maximal benefit of robotic-assisted complex HPB surgery.

Evaluation of ECHO PS Positioning System in a Porcine Model of Simulated Laparoscopic Ventral Hernia Repair.

Purpose. Operative efficiency improvements for laparoscopic ventral hernia repair (LVHR) have focused on reducing operative time while maintaining overall repair efficacy. Our objective was to evaluate procedure time and positioning accuracy of an inflatable mesh positioning device (Echo PS Positioning System), as compared to a standard transfascial suture technique, using a porcine model of simulated LVHR. Methods. The study population consisted of seventeen general surgeons (n = 17) that performed simulated LVHR on seventeen (n = 17) female Yorkshire pigs using two implantation techniques: (1) Ventralight ST Mesh + Echo PS Positioning System (Echo PS) and (2) Ventralight ST Mesh + transfascial sutures (TSs). Procedure time and mesh centering accuracy overtop of a simulated surgical defect were evaluated. Results. Echo PS demonstrated a 38.9% reduction in the overall procedure time, as compared to TS. During mesh preparation and positioning, Echo PS demonstrated a 60.5% reduction in procedure time (P < 0.0001). Although a trend toward improved centering accuracy was observed for Echo PS (16.2%), this was not significantly different than TS. Conclusions. Echo PS demonstrated a significant reduction in overall simulated LVHR procedure time, particularly during mesh preparation/positioning. These operative time savings may translate into reduced operating room costs and improved surgeon/operating room efficiency.

Endovascular graft repair for blunt traumatic disruption of the thoracic aorta: experience at a nonuniversity hospital.

Blunt thoracic aortic injury (BAI) represents the second leading cause of death from blunt trauma. Admission rates for BAI are extremely low because instant fatality occurs in nearly 75 per cent of patients. Management strategies have transitioned from the more invasive immediate thoracotomy to delayed endograft repair with strict hemodynamic management. In this study, we assess outcomes and complications of open versus endograft repair for BAI at a nonuniversity hospital. Retrospective chart review was conducted on 49 patients admitted to a Level I trauma center who incurred BAI from 2004 to 2011. Collected data points included demographics, mortality, complication rates, and intensive care unit and hospital length of stay (LOS). Twenty-one patients underwent open thoracotomy (OPEN), whereas 28 patients were managed with thoracic endovascular aortic repair (TEVAR). The overall 30-day mortality rate was significantly lower comparing TEVAR to OPEN (7.1 vs 50%, P = 0.028); seven deaths occurred in the OPEN group versus two with TEVAR. Overall complications, including mortality, acute respiratory distress syndrome, renal failure, pneumonia, pulmonary embolism, and cardiac arrest, were fewer after TEVAR (32.1 vs 81.0%, P < 0.001) despite similar injury severity. Survivor hospital LOS (26.0 ± 15.3 vs 27.7 ± 18.7 days, P = 0.79), intensive care unit LOS (13.5 ± 10.9 vs 12.7 ± 8.8 days, P = 0.94), and ventilator days (11.4 ± 13.4 vs 16.4 ± 14.5 days, P = 0.25) were similar. Early nonoperative management with TEVAR for BAIs is a feasible and effective management strategy. Improved patient outcomes over traditional open thoracotomy in the presence of similar injury severity can be seen after TEVAR in the nonuniversity hospital setting.

Minimally invasive esophagectomy in the community hospital setting.

We report our initial experience with minimally-invasive esophagectomy in 32 patients at Carolinas Medical Center, a community academic medical center. Indications for surgery were adenocarcinoma in 27, squamous cell carcinoma in 3, and benign stricture in 2. Transthoracic Ivor-Lewis esophagectomy with laparoscopy and thoracoscopy was performed in 28, a 3-stage esophagectomy in 3, and transhaital esophagectomy in 1. There was no operative mortality and median hospital stay was 10.5 days for patients treated with minimally invasive esophagectomy. This compares with an operative mortality of 8.9% and median hospital stay of 17 days for open esophagectomy in our institution.