Thomas C. Schmandra

Effect of insufflation gas and intraabdominal pressure on portal venous flow during pneumoperitoneum in the rat

BackgroundCarbon dioxide, the primary gas used to establish a pneumoperitoneum, causes numerous systemic effects related to cardiovascular function and acid-base balance. Therefore, the use of other gases, such as helium, has been proposed. Furthermore, the pneumoperitoneum itself, with the concomitant elevation of intraabdominal pressure, causes local and systemic effects that have been only partly elucidated. Portal blood flow, which plays an important role in hepatic function and cell-conveyed immune response, is one of the affected parameters.MethodsAn established animal model (rat) of laparoscopic surgery was extended by implanting a periportal flow probe. Hemodynamics in the portal vein were then measured by transit-time ultrasonic flowmetry during increasing intraabdominal pressure (2–12 mmHg) caused by gas insufflation (carbon dioxide vs helium).ResultsThe installation of the pneumoperitoneum with increasing intraperitoneal pressure led to a significant linear decrease in portal venous flow for both carbon dioxide and helium. At higher pressure levels (8–12 mmHg), portal blood flow was significantly lower (1.5–2.5-fold) during carbon dioxide pneumoperitoneum. An intraabdominal pressure of 8 mmHg caused a decrease to 38.2% of the initial flow (helium, 59.7%); whereas at 12 mmHg, portal flow was decreased to 16% (helium, 40.5%).ConclusionElevated intraabdominal pressure generated by the pneumoperitoneum results in a reduction of portal venous flow. This effect is significantly stronger during carbon dioxide insufflation. Portal flow reduction may compromise hepatic function and cell-conveyed immune response during laparoscopic surgery.

Roboterassistierte laparoskopische Cholecystektomie und Fundoplicatio – erste Erfahrungen mit dem Da-Vinci-System

Abstract. We report on our first five robot-assisted laparoscopic cholecystectomies and one fundoplication (Da Vinci system). No postoperative complications were observed. For the cholecystectomies (three elective and two acute cases) mean operation time was 1 h 35 min, and mean hospital stay was 5 days; for fundoplication the operation time was 2 h 15 min. The main advantages seem to be improved visualization by using a stereo camera und ease of precise dissection by micromechanical instruments directed by masterslaves from a distant console. The main disadvantage is the high cost. To fully evaluate the benefit for the patient, prospective clinical trials are warranted.Zusammenfassung. Wir berichten über unsere ersten Erfahrungen mit der roboterassistierten laparoskopischen Cholecystektomie (n = 5) und Fundoplicatio (n = 1). Stereooptik und Instrumente, die von einer Konsole aus über Masterarme vom Operateur gesteuert werden, erlauben eine präzise und sichere Operation. Subjektiv ist die Kombination eines dreidimensionalen Sehens, gepaart mit der dimensionalen Erweiterung des Instrumenteneinsatzes, im Vergleich zur herkömmlichen laparoskopischen Technik der größte Vorteil. Da zur Zeit der Einsatz des Da-Vinci-Systems noch mit erheblichen Kosten verbunden ist, dürften der Verbreitung dieser Technik enge Grenzen gesetzt sein. Es ist aber absehbar, daß Entwicklungen der Computertechnik, der Mikro/Nanomechanik und haptischen Resonanz dazu führen werden, Robotiktechnologie auch im Bereich der Visceralchirurgie präsent zu machen.

Nutritional Support after Open Liver Resection: A Systematic Review

Background: Perioperative nutrition in patients with limited liver function after partial hepatic resection is still controversial. In particular, the significance of perioperative total enteral nutrition remains unresolved. The aim of this review is to investigate the impact of early postoperative total enteral nutrition on convalescence after partial liver resection. Materials and Methods: In an internet-based Medline-Search (time course: 1960–08/2005) a total of five prospective, randomized controlled trials were found comparing the impact of enteral and parenteral nutrition after liver resection. After study validity had been established, a systematic review was undertaken (odds ratio, 95% confidence interval, p < 0.05 level of significance; Review Manager 4.2®, The Cochrane Collaboration). Primary endpoints were complication rate (infection, organ malfunction) and mortality. Standardized immune parameters were also surveyed. Results: Statistical analysis showed that enteral nutrition resulted in a significantly lower rate (p = 0.04) of wound infection and catheter-related complications than parenteral nutrition did. No statistically significant differences in mortality due to enteral or parenteral nutrition could be found. Patients receiving enteral nutrition showed better postoperative immune competence. Conclusion: Early enteral nutrition after liver resection is a safe procedure. Compared to parenteral nutrition it is associated with a decreased incidence of postoperative complications. Facing the inhomogeneity of these trials, especially in nutrition protocols and end points, this first systematic review stresses the need for an update of the importance of early enteral nutrition after liver resection within randomized controlled multicenter trials.

Markov cohort simulation study reveals evidence for sex-based risk difference in intensive care unit patients

BACKGROUND Despite great advances in intensive care medicine, sepsis still is the leading cause of death. Different strategies have been developed to file the patient data into scoring systems, primarily to predict the outcome. The Markov simulation-predominantly used in economic science to describe chains of events depending on and influencing each other-seems to be an interesting and new approach in analyzing the course of disease of critically ill patients in an intensive care unit (ICU). Using such a Markov model, this study analyzes data from 660 surgical ICU patients, 44 of whom died of sepsis. METHODS A three-state Markov model (integrating sepsis, adult respiratory distress syndrome, and mortality) was constructed to describe the course of disease of critically ill patients in defined cycles and to develop the risk profile of different groups of patients. The model enables the comparison between age- and sex-related survival rates and shows the difference in life expectancy compared with an average untreated standard population. RESULTS Women aged up to 30 years (G1F) show the best prognosis (mortality after 19 cycles 8.3%). On the contrary, the corresponding male group (G1M) demonstrates the worst outcome (mortality after 19 cycles 57.7 %). CONCLUSIONS The findings of this study fit into the current discussion that female patients are better positioned to meet the challenge of sepsis.

Strain Measurement of Abdominal Aortic Aneurysm with Real-time 3D Ultrasound Speckle Tracking

OBJECTIVES Abdominal aortic aneurysm rupture is caused by mechanical vascular tissue failure. Although mechanical properties within the aneurysm vary, currently available ultrasound methods assess only one cross-sectional segment of the aorta. This study aims to establish real-time 3-dimensional (3D) speckle tracking ultrasound to explore local displacement and strain parameters of the whole abdominal aortic aneurysm. MATERIALS AND METHODS Validation was performed on a silicone aneurysm model, perfused in a pulsatile artificial circulatory system. Wall motion of the silicone model was measured simultaneously with a commercial real-time 3D speckle tracking ultrasound system and either with laser-scan micrometry or with video photogrammetry. After validation, 3D ultrasound data were collected from abdominal aortic aneurysms of five patients and displacement and strain parameters were analysed. RESULTS Displacement parameters measured in vitro by 3D ultrasound and laser scan micrometer or video analysis were significantly correlated at pulse pressures between 40 and 80 mmHg. Strong local differences in displacement and strain were identified within the aortic aneurysms of patients. CONCLUSION Local wall strain of the whole abdominal aortic aneurysm can be analysed in vivo with real-time 3D ultrasound speckle tracking imaging, offering the prospect of individual non-invasive rupture risk analysis of abdominal aortic aneurysms.

Chronic mesenteric ischemia: Time to remember open revascularization

Chronic mesenteric ischemia is caused by stenosis or occlusion of one or more visceral arteries. It represents a therapeutic challenge and diagnosis and treatment require close interdisciplinary cooperation between gastroenterologist, vascular surgeon and radiologist. Although endovascular treatment modalities have been developed, the number of restenoses ultimately resulting in treatment failure is high. In patients fit for open surgery, the visceral arteries should be revascularized conventionally. These patients will then experience long term relief from the symptoms, a better quality of life and a better overall survival.

Surgical strategies – anastomosis or stoma, second look – when and why?

Introduction: The indication for performing a primary anastomosis or an intestinal stoma has to be confirmed or negated for every individual case of intestinal ischemia. Discussion: In right-sided colonic emergency, primary anastomosis is possible except when associated with generalized peritonitis. In left-sided colonic ischemia and necrosis, delayed anastomosis is the preferred alternative. In ischemia following surgery for abdominal aortic aneurysms, primary anastomosis is contraindicated. In ischemia of the small bowel, an end-to-end anastomosis should be established whenever possible. Conclusion: In the case of intestinal ischemia, a second-look laparotomy is mandatory 24–48 h after initial surgery to ensure bowel viability. This second look should be performed regard-less of the patients postoperative clinical status. Laparoscopy has been successfully used for reexploration in intestinal ischemia, but one has to be aware of the present limitations of experience using this technique.

Altered in-stent hemodynamics may cause erroneous upgrading of moderate carotid artery restenosis when evaluated by duplex ultrasound

OBJECTIVE To assess the influence of stent application on in-stent hemodynamics under standardized conditions. METHODS Ovine common carotid arteries before and after stent (6 × 40 mm, sinus-Carotid-RXt, combined open-closed cell design; Optimed, Ettlingen, Germany) application were used. Plastic tubes, 10 mm in length, simulating stenosis were placed in the middle of the applied stent to induce different degrees of stenosis (moderate 57.8% and severe 76.4%). Flow velocity and dynamic compliance were, respectively, measured with ultrasound and laser scan; proximal, in-stent, and distal to the stented arterial segment (1 cm proximal and distal) in a pulsatile ex vivo circulation system. RESULTS Stent insertion caused the in-stent peak systolic velocity to increase 22% without stenosis, 31% with moderate stenosis, and 23% with severe stenosis. Stent insertion without stenosis caused no significant increase in in-stent end-diastolic velocity (EDV) but a 17% increase with moderate stenosis. In severe stenosis, EDV was increased 56% proximal to the stenosis. Compliance was reduced threefold in the middle of the stented arterial segment where flow velocity was significantly increased. CONCLUSIONS With or without stenosis, stent introduction caused the in-stent peak systolic velocity to become significantly elevated compared with a nonstented area. EDV was also increased by stent insertion in the case of moderate stenosis. The stent-induced compliance reduction may be causal for the increase in flow velocity since the stent-induced flow velocity elevation appeared in the stented area with low compliance. Because of altered hemodynamics caused by stent introduction when measured by duplex ultrasound, caution is prudent in concluding that carotid artery stenting is associated with a higher restenosis rate than carotid endarterectomy. Mistakenly upgrading moderate to severe restenosis could result in unnecessary reintervention. CLINICAL RELEVANCE Clinical experience and prior studies support the supposition that restenosis after carotid artery stenting in carotid lesions displays erroneously elevated velocity when evaluated by duplex ultrasound (DUS), thus contributing to misleading interpretation of the degree of stenosis. This study, in contrast to studies of other groups, employs exactly the same conditions to measure flow with DUS in an unstented and then stented section of the carotid artery. Since DUS is the first-choice tool for carotid artery evaluation, knowledge about inexactness of the method is essential to avoid errors in treatment or follow-up decisions.

Cirrhosis serum induces a nitric oxide-associated vascular hyporeactivity of aortic segments from healthy rats in vitro

Objective Arterial vasodilation with concomitant hyperdynamic circulation are common findings in liver cirrhosis. Nitric oxide acting at a local level has been suggested to be pathophysiologically relevant in this context. Several systemic factors in conjunction with nitric oxide might interfere with the observed phenomena. Design The study has been designed to demonstrate the influence of cirrhotic serum on the nitric oxide system and vascular contractility. Methods The contractile response of aortic segments from healthy rats was studied in vitro after incubation with serum of healthy and cirrhosis-induced rats (1 week, 2 weeks, 3 weeks and 4 weeks after bile duct ligation). A cumulative dose response curve to phenylephrine (10−–10−4 mol) was established before and after incubation with nitric oxide synthesis blocker Nω-nitro-L-arginine, the more selective aminoguanidine (nitric oxide synthase [NOS]-2 inhibitor) and W7 (NOS-3 inhibitor). NOS-2 expression in incubated aortic rings was evaluated by Western blot analysis. Results A 4-hour incubation with serum of cirrhosis-induced rats reduced the maximum contractile response to phenylephrine to 66.8 ± 9.1% after 1 week, 50.4 ± 7.8% after 2 weeks, 43.2 ± 2.8% after 3 weeks and 35 ± 5.2% after 4 weeks of bile duct ligation. This reduction in the contractility response to phenylephrine was completely reversed by blocking nitric oxide synthesis with Nω-nitro-L-arginine and aminoguanidine, but not after W7. Incubation with cirrhotic serum induced NOS-2 expression in aortic rings. In Western blot analysis, the most intensive signal for NOS-2 protein was obtained in rings incubated with serum from rats 3 weeks and 4 weeks after induction of cirrhosis. Conclusions Cirrhotic serum decreases the contractile response to phenylephrine even in an early stage of secondary cirrhosis. Reversibility of this effect after nitric oxide synthesis blockade suggests an induction of nitric oxide synthesis by systemic factors as a major point in vascular hyporeactivity to vasoconstrictors in cirrhosis.

First successful complete replantation of a traumatic hemipelvectomy: follow-up after 30 months.

Traumatic hemipelvectomy is a severe, however rare injury associated with high lethality. Up to now, immediate surgical completion of the amputation has been recommended as a lifesaving therapy. We present a case of near complete hemipelvectomy with open fracture of the ileosacral joint, wide open symphysis and severe soft tissue trauma including a decollement around the pelvis. Successful complete replantation was performed by primary internal stabilisation and revascularisation using vascular grafts. In the further hospital course, numerous revisions of the soft tissue injury and reconstructive surgery were needed. Thirty months later, the patients condition is physically and psychologically stable and he is able to walk using crutches. The key point of successful management was skilled emergency damage control surgery followed by dedicated surgical care to avoid septic complications.