Clinical application of modern ultrasound techniques after liver transplantation.

Liver transplantation has been established as a first-line therapy for a number of indications. Conventional ultrasound and contrast-enhanced ultrasound (CEUS) are methods of choice during the postoperative period as a safe and fast tool to detect potential complications and to enable early intervention if necessary. CEUS increases diagnostic quality and is an appropriate procedure for the examination of vessels and possibly bile ducts. This article presents the state of the art of ultrasound application during the early period after liver transplantation. It addresses common vascular complications and describes the identification of postoperative abnormal findings using ultrasound and CEUS.

Pressure Measurement Techniques for Abdominal Hypertension: Conclusions from an Experimental Model.

Introduction. Intra-abdominal pressure (IAP) measurement is an indispensable tool for the diagnosis of abdominal hypertension. Different techniques have been described in the literature and applied in the clinical setting. Methods. A porcine model was created to simulate an abdominal compartment syndrome ranging from baseline IAP to 30 mmHg. Three different measurement techniques were applied, comprising telemetric piezoresistive probes at two different sites (epigastric and pelvic) for direct pressure measurement and intragastric and intravesical probes for indirect measurement. Results. The mean difference between the invasive IAP measurements using telemetric pressure probes and the IVP measurements was -0.58 mmHg. The bias between the invasive IAP measurements and the IGP measurements was 3.8 mmHg. Compared to the realistic results of the intraperitoneal and intravesical measurements, the intragastric data showed a strong tendency towards decreased values. The hydrostatic character of the IAP was eliminated at high-pressure levels. Conclusion. We conclude that intragastric pressure measurement is potentially hazardous and might lead to inaccurately low intra-abdominal pressure values. This may result in missed diagnosis of elevated abdominal pressure or even ACS. The intravesical measurements showed the most accurate values during baseline pressure and both high-pressure plateaus.

Large-scale referencing of the telemetric neurovent-P-tel intracranial pressure sensor in a porcine model.

The Neurovent-P-tel sensor is a promising device for telemetric intracranial pressure (ICP) measurements in cases of complex hydrocephalus. Data on its accuracy within a broad ICP range are missing. We applied a porcine model for large-scale manipulation of the ICP values. The telemetric ICP sensor was referenced against ICP values measured directly from a water column within a riser tube. A total of 34 comparative ICP measurements within an ICP range from 2 cm H2O to 31 mm Hg were performed. The mean difference between both measurement techniques was 0.4 mm Hg. The limits of agreement, where 95% of differences between both methods are expected, were from -2.4 to 3.1 mm Hg. The telemetric Neurovent-P-tel sensor system provides good accuracy within a broad range exceeding normal ICP values and might be useful in clinical practice.

Differential pressure in shunt therapy: investigation of position-dependent intraperitoneal pressure in a porcine model.

OBJECT: The differential pressure between the intracranial and intraperitoneal cavities is essential for ventriculoperitoneal shunting. A determination of the pressure in both cavities is decisive for selecting the appropriate valve type and opening pressure. The intraperitoneal pressure (IPP)-in contrast to the intracranial pressure-still remains controversial with regard to its normal level and position dependency. METHODS: The authors used 6 female pigs for the experiments. Two transdermal telemetric pressure sensors (cranial and caudal) were implanted intraperitoneally with a craniocaudal distance of 30 cm. Direct IPP measurements were supplemented with noninvasive IPP measurements (intragastral and intravesical). The IPP was measured with the pigs in the supine (0°), 30°, 60°, and vertical (90°) body positions. After the pigs were euthanized, CT was used to determine the intraperitoneal probe position. RESULTS: With pigs in the supine position, the mean (± SD) IPP was 10.0 ± 3.5 cm H2O in a mean vertical distance of 4.5 ± 2.8 cm to the highest level of the peritoneum. The difference between the mean IPP of the cranially and the caudally implanted probes (Δ IPP) increased according to position, from 5.5 cm H2O in the 0° position to 11.5 cm H2O in the 30° position, 18.3 cm H2O in the 60° position, and 25.6 cm H2O in the vertical body position. The vertical distance between the probe tips (cranially implanted over caudally implanted) increased 3.4, 11.2, 19.3, and 22.3 cm for each of the 4 body positions, respectively. The mean difference between the Δ IPP and the vertical distance between both probe tips over all body positions was 1.7 cm H2O. CONCLUSIONS: The IPP is subject to the position-dependent hydrostatic force. Normal IPP is able to reduce the differential pressure in patients with ventriculoperitoneal shunts.

Incidence, risk factors and management of incisional hernia in a high volume liver transplant center.

BACKGROUND: Incisional hernia after liver transplantation is a common complication with an incidence between 5% and 34%. This prospective study analyzed risk factors, surgical management and long-term results after hernia repair. MATERIAL AND METHODS: From February 2002 until August 2009, 810 liver transplantations were performed. 77 patients (9.5%) underwent incisional hernia repair after a median time of 21.1 months (4.6-76.7) following transplant. These patients were compared to patients without hernia (n=733). RESULTS: No statistically significant differences between the groups were observed with respect to gender, underlying liver disease, Child-Pugh classification, MELD-Score and preoperative renal failure (p=NS). Multivariate analysis revealed advanced age (p=0.014), body mass index (p=0.016), and re-laparotomies (p<0.001) as independent risk factors for incisional hernias. Pre-existing diabetes mellitus and immunosuppression with mycophenolate mofetil reached significance only in the univariate analysis (p<0.001). Recurrent hernia was observed in 12 of 77 patients (15.6%) at a median time of 7.9 months (4.8-46.8) after primary surgical repair. The recurrence rate after intraperitoneal onlay mesh implantation was lower compared to other mesh techniques (7.7% vs. 21.4%). CONCLUSIONS: The risk factors for the development of incisional hernias in liver transplant patients are similar to patients with prior abdominal surgery for other reasons. Intraperitoneal onlay mesh implantation may lead to a decrease of hernia recurrences. The role of immunosuppression in the genesis of incisional hernias requires further elucidation.

Evaluation of a new large animal model for controlled intracranial pressure changes induced by capnoperitoneum.

BACKGROUND: A standardized large animal model for controlled ICP manipulation within a relevant range and repetitive ICP measurements is missing. We sought to develop such a model on the base of controlled IPP changes induced by capnoperitoneum. METHODS: We utilized six female pigs (mean body weight 59.5 ± 18.4 kg) for experiments. A ventricular catheter connected with a burr hole reservoir was implanted. ICP was measured directly as cm H2O within a riser tube after percutaneous cannulation of the reservoir. A noninvasive intraperitoneal pressure (IPP) measurement was established (intravesical). Animals were placed in lateral position and a capnoperitoneum was induced. Measurements of ICP, IPP, MAP and respiratory parameters were performed at baseline IPP and after CO2 insufflation to IPP levels of 20 and 30 mmHg. RESULTS: Baseline IPP in lateral position referenced to median line was 9.8 (±2) mm Hg, while corresponding ICP was 10 (±2.2) mm Hg. After IPP elevation to 20 mmHg, ICP increased to 18.8 (±1.9) mm Hg. At 30 mmHg IPP, ICP increased to 22.8 (±2.8) mm Hg. Except peak airway pressure, all other parameters were kept constantly. Mean ICP variation in the individual subject was 13.4 (±2.5) mm Hg, while a ICP range from minimum 9 to maximum 31 mmHg was documented. CONCLUSIONS: We report a large animal model that allows (1) repeated measurement of the ICP and (2) manipulation of the ICP within a large pressure range by controlled IPP changes due to capnoperitoneum.

Natural orifice transluminal endoscopic surgery in surgical oncology: analysis of indications and feasibility in cancer patients.

BACKGROUND/AIMS: Natural orifice endoscopic surgery (NOTES) is an emerging technique that has been postulated as a promising alternative to laparoscopy in the field of minimal invasive surgery. Until now appropriate indications, safe access routes and general feasibility of this approach have not been defined exactly in surgical oncology. METHODOLOGY: A total of 474 patients undergoing cancer surgery were analyzed regarding possible applications of transluminal endoscopic surgery. Patient with potential indications underwent intraoperative endoscopy to evaluate technical aspects, indications and intraoperative feasibility. RESULTS: A potential indication for transluminal surgery was found in 54 of 474 patients (11%) undergoing abdominal cancer surgery. Staging of gastrointestinal tumors was considered the main indication (45%) followed by splenectomy (11%) and diagnostic excision (11%). As a potential access route the transgastric approach was considered in 42 patients (66%) and the transcolonic approach in 18 patients (28 %). Of these 42 patients, 19 (30%) presented with significant intra-abdominal adhesions which would have resulted in a more complicated procedure. Accurate transluminal orientation was considered impossible in 13 cases (20%). CONCLUSIONS: Although some indications for NOTES procedures in surgical oncology have been identified in this study these techniques have to be assessed cautiously. Implementation of NOTES in surgical oncology is currently difficult because of technical problems, lack of intraoperative orientation and abdominal adhesions.

Establishing Nd:YAG laser-based left lateral liver resection: comparison of open, laparoscopic, and hand-assisted approach in a porcine Model.

INTRODUCTION: Aim of this study was to assess the feasibility and safety of a 1064 nm Nd:YAG laser for left lateral liver resection in a porcine model. Laparoscopy and hand-assisted laparoscopic surgery were evaluated and compared with conventional open surgery. METHODS: Animals were randomized for open, hand assisted, and laparoscopic left lateral liver lobe resection. Primary endpoints were intraoperative blood loss, dissection time, laboratory changes, and abdominal wall adhesions. In addition intraoperative cardiopulmonary data, postoperative clinical parameters, and necropsy findings were analyzed. RESULTS: Liver resection was successful in all animals without intraoperative or postoperative mortality. Laparoscopic dissection time was significantly increased. Average blood loss was 340 mL for open surgery and 320 mL for hand-assisted surgery. Blood loss during laparoscopy was significantly smaller with a mean of 180 mL. Postmortem findings revealed extensive adhesions for open surgery whereas hand assisted and laparoscopic animals showed limited adhesions in the upper abdomen. CONCLUSIONS: Nd:YAG laser-based liver resection is a potentially safe and feasible technique. The minimal access approaches show comparable results to the open technique with reduced abdominal trauma and less adhesions. Laparoscopy was more time consuming but showed reduced blood loss compared with both other groups.

Initial results of MR-guided liver resection in a high-field open MRI.

BACKGROUND: The goal of this study was to evaluate high-field open magnetic resonance imaging (MRI) for intraoperative real-time imaging during hand-assisted laparoscopic liver resection. MR guidance has several advantages compared to ultrasound and may represent a future technique for abdominal surgery. Various MRI-safe and -compatible instruments were developed, tested, and applied to realize minimally invasive liver surgery under MR guidance. As proof of the concept, liver resection was performed in a porcine model. METHODS: All procedures were conducted in a 1.0-T open MRI unit. Imaging quality and surgical results were documented during three cadaveric and two live animal procedures. A nonferromagnetic hand port was used for manual access and the liver tissue was dissected using a Nd:YAG laser. RESULTS: The intervention time ranged from 126 to 145 min, with a dissection time from 11 to 15 min. Both live animals survived the intervention with a blood loss of 250 and 170 ml and a specimen weight of 138 and 177 g. A dynamic T2W fast spin-echo sequence allowed real-time imaging (1.5 s/image) with good delineation of major and small hepatic vessels. The newly developed MR-compatible instruments and camera system caused only minor interferences and artifacts of the MR image. CONCLUSION: MR-guided liver resection is feasible and provides additional image information to the surgeon. We conclude that MR-guided laparoscopic liver resection improves the anatomical orientation and may increase the safety of future minimally invasive liver surgery.

Evidence-based perioperative management: strategic shifts in times of fast track surgery.

Changes in perioperative management is an ever evolving subject. The primary aim is to improve patient care and more recently to increase economic efficacy. Data from various randomized studies have caused a shift from traditional care concepts towards evidence based multimodal treatment strategies. They may lead to dramatic changes in perioperative patient care such as the routine use of nasogastric decompression, mechanical bowel preparation and established nutrition schemes. Further aspects of modern perioperative patient care include epidural analgesia, antibiotic prophylaxis, intraoperative fluid management and early mobilization. It has been generally accepted that these multimodal treatment concepts also known as "fast track surgery" show no differences in patient morbidity while significantly reducing patient discomfort and duration of hospitalization. However, despite the evidence-based superiority, widespread implementation has not yet occurred. The aim of this review is to highlight and discuss current changes and to show future perspectives of perioperative treatment strategies.

Evaluation of laparoscopic liver resection with two different Nd:YAG lasers for future use in a high-field open MRI.

OBJECTIVE: Laparoscopic liver surgery is a safe and feasible technique for the treatment of benign and malignant liver tumors and has been well established at many specialized centers. Many different techniques of tissue dissection have been developed. As an alternative various lasers have been applied to conventional liver resections. Laser surgery is potentially beneficial for laparoscopic liver resection, allowing parenchymal dissection and vessel coagulation. A second advantage is the non-ferromagnetic character of this instrument, which facilitates magnetic resonance (MR)-guided interventions. In this study two different Nd:YAG lasers were evaluated for laparoscopic liver resection in a porcine model. In other studies this technique will be transferred into an interventional open MRI for image-guided liver resection. MATERIALS AND METHODS: We used 1064-nm and 1318-nm Nd:YAG lasers for laparoscopic wedge, segmental, and left lateral liver lobe resection. During the intervention blood loss, resection time, and cardiopulmonary parameters were quantified. The resected specimen underwent histomorphometric analysis for thermal tissue effects, including parenchymal carbonization, necrosis, and vessel coagulation. RESULTS: The resected volume showed a positive correlation with intraoperative blood loss, which increased from wedge resection (245 mL, SD +/- 71 mL) and segment resection (325 mL), to left lateral resection (455 mL). Total parenchymal dissection was slightly faster with the 1064-nm Nd:YAG laser (9 min, SD +/- 5 min) compared with the 1318-nm Nd:YAG laser (11 min, SD +/- 4 min). Thermally-induced vessel sealing was shown for liver veins and arteries to a maximum diameter of 2 mm. CONCLUSION: Laparoscopic liver resection with both Nd:YAG lasers is a safe and feasible technique, allowing parenchymal dissection and coagulation. The 1064-nm Nd:YAG laser showed increased tissue damage with more effective coagulation capability than the 1318-nm Nd:YAG laser. Because of its non-ferromagnetic characteristics, laser-based laparoscopic liver resection is potentially useful for image-guided surgery in an open MRI.

The effect of endoscopic treatment on healing of anastomotic leaks after anterior resection of rectal cancer.

BACKGROUND: Despite surgical advances, anastomotic leaks remain a major complication after rectal resection. Endoscopic techniques are increasingly used as an alternative or in addition to conventional operative therapy of anastomotic leakage. We have analyzed the impact of endoscopic treatment on the outcome of patients with leaks after resection of rectal cancer. METHODS: From January 2000 to December 2005, rectal resection was performed in 274 patients with rectal cancer. Anastomotic leakage was observed in 29 patients (11%). Nine of these patients received a protective ileostomy. The remaining 20 patients underwent either conventional operative or endoscopic treatment. Both groups were analyzed regarding complications, necessity of operative reintervention, hospitalization, anastomotic healing time, and stoma reversal rate. RESULTS: The endoscopic group included 13 patients who underwent endoscopic debridement in combination with stenting, endoluminal vacuum therapy, or fibrin injection. The remaining 7 patients underwent reoperation-secondary ileostomy creation (n = 4), Hartmann procedure (n = 2), or anastomotic repair (n = 1). Stoma creation was necessary in 7 of 13 patients (54%) in the endoscopic group and in 6 of 7 patients (86%) in the operative group. There were no significant differences regarding postoperative septicemia (39 vs 43%), duration of intensive care (13 vs 11 days), or time of hospitalization (25 vs 26 days) for endoscopic and conventional therapies. Mean healing time of the anastomotic leak in the endoscopic and conventional group was 105 and 173 days, respectively. The stoma reversal rate was similar in both groups (50 vs 57%), but the overall rate of patients without colostomy was higher in the endoscopic group (77 vs 57%). CONCLUSION: Endoscopic therapy in combination with effective operative drainage may support healing of anastomotic leaks after rectal resection. However, the majority of patients require operative reintervention with bowel diversion despite endoscopic treatment.