K. Tobias E. Beckurts

Variability of Size and Shape of Necrosis Induced by Radiofrequency Ablation in Human Livers: A Volumetric Evaluation

Background: Definite size and shape of radiofrequency-induced ablations (RFAs) cannot be evaluated intraoperatively. Instead, surgeons choose a radiofrequency device that is supposed to cause a necrosis of a determined size greater than the malignant lesion. The aim of this study was to measure the variability of the induced necroses postoperatively and to define a reproducible ablation volume in human liver.Methods: In 24 patients, 34 RFA procedures were performed with single applications of the device. The deployment was 3 cm (n = 16), 4 cm (n = 5), or 5 cm (n = 13). The induced necroses were analyzed by volumetric reconstructions of computed tomography (CT) scans. Measured volumes were compared with the expected volumes. Furthermore, the shape of the necrosis was classified according to an index of the diameters.Results: The measured volumes of postoperative necroses were 14 ± 8 cm3 (deployment, 3 cm), 24 ± 12 cm3 (4 cm), and 45 ± 42 cm3 (5 cm). The diameter of a sphere fitted into the necroses reached 2.9 ± .5 cm (3 cm), 3.5 ± .7 cm (4 cm), and 4.1 ± 1.1 cm (5 cm), at P < .02, significantly smaller than the deployment. The classification of shapes yielded a spherical shape (n = 14), a teardrop shape (n = 13), or an irregular shape (n = 7). The energy consumption was 2.1 ± 1.5 kJ/cm3 (3 cm), 2.6 ± .5 kJ/cm3 (4 cm), or 3.5 ± 2.0 kJ/cm3 (5 cm).Conclusions: The diameter of RFA-induced liver necrosis is significantly smaller than expected from needle deployment, especially with full-needle deployment. The shape of the lesion differs in more than half of the cases from the anticipated spherical pattern. The upper limit for reproducible necrosis induction is a tumor diameter of 3.4 cm.

Portal Vein Arterialization Increases Hepatocellular Apoptosis and Inhibits Liver Regeneration

BACKGROUND Portal vein arterialization is performed in particular situations to guarantee sufficient blood flow in the portal vein. In addition, some authors have postulated a proliferation-promoting influence of portal vein arterialization on the liver tissue. However, portal vein arterialization is an unphysiological procedure: It increases portal blood flow and blood pressure as well as oxygenation of the liver tissue. On the other hand, it reduces the influx of hepatotrophic factors from the portal venous blood. The aim of these experiments was to investigate apoptosis and proliferation of hepatocytes during various conditions of the portal perfusion. MATERIALS AND METHODS After 70% liver resection in Lewis rats, the following four experimental groups were formed differing in portal perfusion: (I) hyperperfused, nonarterialized; (II) flow-regulated, nonarterialized; (III) hyperperfused, arterialized; (IV) flow-regulated, arterialized. A warm ischemia of 30 min was kept in all groups. RESULTS Portal vein arterialization of 70% reduced rat livers significantly reduced liver regeneration as shown by a significant reduction in liver weight, body weight, and liver function after 6 wk, in contrast to the group with 70% liver mass reduction and portal venous inflow of the portal vein. Furthermore, we found a significantly elevated number of apoptotic hepatocytes after portal vein arterialization. These results were independent from blood flow regulation of the arterialized portal vein, which caused no improvement of the results. CONCLUSIONS Portal vein arterialization should be performed only temporarily and is clinically not recommended as a permanent option, because of the increased hepatocellular apoptosis and the very distinctive, negative long-term effects on liver weight.

Does continuous mucosal partial carbon dioxide pressure measurement predict leakage of intrathoracic esophagogastrostomy

BACKGROUND Gastroplasty after esophagectomy is associated with relevant morbidity due to anastomotic leakage of the esophagogastrostomy. The aim of this study was to find out whether continuous partial carbon dioxide pressure (pCO2) measurement of the gastric mucosa is an adequate method of monitoring the gastric tube during the postoperative course and of detecting patients with an anastomotic leakage. METHODS Forty-seven patients with esophageal cancer underwent esophagectomy and gastric tube formation with intrathoracic esophagogastrostomy. Postoperatively, mucosal pCO2 of the gastric tube (pCO2i) was measured using continuous tonometry (TONOCAP, Datex Ohmeda). pCO2i was related to the arterial pCO2 (delta pCO2 = pCO2i - pCO2a). RESULTS A total of 4,338 delta pCO2 measurements were recorded. On average, the pCO2i of each patient was monitored over a period of 92 hours. In 5 patients an anastomotic leakage of the esophagogastrostomy developed. The mean delta pCO2 of this group was 31.7 mm Hg (+/-19.3 SD) and significantly higher (p < 0.0001) than that of patients without anastomotic leakage (20.7 mm Hg +/- 12.8 SD). With a delta pCO2 cut-off point of 56 mm Hg measured for 5 hours, the sensitivity was 0.8, the specificity 0.9, and the positive predictive value 0.5. In patients with anastomotic leakage, the peak delta pCO2 preceded clinical symptoms. False positive delta pCO2 measurements (n = 4) were mainly due to severe pneumonia with long-term ventilation. CONCLUSIONS Mucosal pCO2 measurement of the gastric tube can be used as an early indicator of a complicated postoperative course predicting anastomotic leakage of the esophagogastrostomy.

Auxiliary liver transplantation with flow-regulated portal vein arterialization offers a successful therapeutic option in acute hepatic failure--investigations in heterotopic auxiliary rat liver transplantation.

Heterotopic auxiliary liver transplantation (HALT) with portal vein arterialization (PVA) was proposed in acute hepatic failure (AHF). However, clinical results of PVA are controversial because of lacking standardized flow‐regulation. In rats, we examined HALT with flow‐regulated PVA in AHF. Group A: HALT with flow‐regulated PVA and 85% resection of the native liver to induce AHF [acute experiments (n = 8), killing after 7 days (n = 8) and after 6 weeks (n = 11)]. Group B: 85% liver‐resection (n = 10). The average blood‐flow in the arterialized portal vein in HALT achieved normal values (1.7 ± 0.4 ml/min/g liver‐weight). After reperfusion, the diameters of the sinusoids (6.4 ± 0.6 μm), the postsinusoidal venules (31.1 ± 3.3 μm) and the intersinusoidal distance (17.9±0.7 μm) also achieved normal values. The functional sinusoidal density amounted to 335 ± 48/cm. The 6‐week survival was nine of 11 with excellent liver function (Quicks value: 110% ± 7.8%). The hepatobiliary radioisotope scanning with (99mTc) ethyl hepatic iminodiacetic acid (EHIDA) showed no significant differences between the native livers and grafts. The hepatocellular morphology was regular, apart from low‐grade necroses in two grafts. The grafts’ sinusoidal endothelial cells did not show any morphological changes. In group B, however, all rats died from AHF within 6 days. HALT with flow‐regulated PVA achieved good results regarding microcirculation, morphology and function and can reliably bridge AHF.

Peri-Operative and Complication Management for Adenocarcinoma of the Oesophagus and Oesophagigastric Junction

Surgical resection of oesophageal cancer still offers the only chance of cure for this disease. Nevertheless, oesophageal surgery may be accompanied by relevant mortality and morbidity, the causes of which can be both directly related to surgical technique as well as a large spectrum of non-surgical complications. In the last few years, improvements in patient selection and technical advances, as well as elaborated peri- and post-operative management, have helped to reduce these threats.The following article addresses important aspects of patient selection and evaluation, pre-operative preparation, anaesthesia, operative prophylaxis of complications, immediate post-operative care and complication management. All these factors are important contributions to improve the outcome in this challenging medical condition. Nowadays, experienced centres report operative mortality rates of around 5% for radical transthoracic resections (Low et al. 2007; Or-ringer et al. 2007; Ando et al. 2000; Karl et al. 2000; Whooley et al. 2003), down from rates of up to 30 or 40% in previous decades (Earlam and Cunha-Melo 1980). Many factors have contributed to these improvements; some authors claim large volume centres have a tendency to improve results, mostly due to more aggressive management of post-operative complications (Forshaw et al. 2006; van Lanschot et al. 2001; Smith et al. 2008). The following article summarizes the factors that have been identified in the past decades to influence the outcome of major surgery for the resection of adenocarcinoma of the oesophagus.