Poplitealaneurysma

Zusammenfassung: Das Poplitealaneurisma (PA) ist eine typische Erkrankung von Männern über 65 Jahren, bei denen häufig Aneurysmen der Aorta, der iliacalen, femoralen und kontralateralen Poplitealarterie vorkommen. Als Ursache des Poplitealaneurysmas (PA) werden prioritär die Degradation durch Matrixmetalloproteinasen, eine entzündliche Reaktion mit Bildung von reaktiven Sauerstoffradikalen sowie der oxidative Stress in der Arterienwand postuliert. Zwei Drittel der Patienten kommen wegen Symptomen zum Chirurgen, die übrigen wegen eines Zufallsbefundes oder weil bereits die Gegenseite operiert wurde. Die akute und chronische Ischämie mit ihrer hohen Morbidität stehen im Vordergrund. Asymptomatische PA sollten ab einem Durchmesser von 2cm therapeutisch angegangen werden, besonders wenn sie partiell thrombosiert sind. Zur Diagnostik reicht eine Duplexuntersuchung. Die digitale Subtraktionsangiographie ist die wichtigste Untersuchung für die Operationsplanung. Lokalisierte Befunde, die auf die Kniekehle begrenzt sind, können von dorsal, langstreckige PA müssen durch einen Zugang von medial mit einem Interponat überbrückt werden. Dabei ist eine autologe Vene dem Kunststoffinterponat vorzuziehen. Im Fall eines Veneninterponates oder -bypasses kann mit einer Offenheitsrate von 85% nach 5Jahren gerechnet werden. Endografts sollen nur ausnahmsweise oder im Rahmen von Studien eingesetzt werde

Pharmacokinetics of antimicrobial agents in anuric patients during continuous venovenous haemofiltration

Background. The optimal drug dosing in anuric patients undergoing continuous haemofiltration is a difficult task. More pharmacokinetic data is needed to derive practical guidelines for dosage adjustments. Methods. Drug elimination of various antimicrobial agents (amikacin, amoxycillin, ceftazidime, ciprofloxacin flucloxacillin, imipenem, netilmicin, penicillin G, piperacillin, sulphamethoxazole, tobramycin, vancomycin) was studied in 24 patients with acute renal failure treated by pump-assisted continuous venovenous haemofiltration (CVVH). Concentrations of serial blood and ultrafiltrate samples were determined by HPLC or by fluorescence polarization immunoassay. Total body clearance (CL) and haemofilter clearance (CLf) rates were determined by standard model-independent equations. Data from published literature on fractions not bound to proteins (fu), non-renal drug clearance fractions (Qo) and normal clearance values (CLn) were used to derive a pharmacokinetic model, taking into account drug removal by ultrafiltration and by non-renal clearance. Results. A total of 37 treatment periods was studied. Blood flow through the haemofilters was 100 ml/min resulting in an average ultrafiltrate flow rate (UFR) of 13.2±4.6 (range 3.2-22.1) ml/min. Acceptable correlations of calculated and measured haemofilter clearances and total body clearances were obtained. Conclusions. Total body clearance in anuric patients during CVVH is predictable from drug properties, which are generally known. The individual dosage requirements may be calculated by multiplying Qo+fu UFR/CLn with the dose considered appropriate in the absence of renal impairmen

Estimating time-varying effects for overdispersed recurrent events data with treatment switching

In the analysis of multivariate event times, frailty models assuming time-independent regression coefficients are often considered, mainly due to their mathematical convenience. In practice, regression coefficients are often time dependent and the temporal effects are of clinical interest. Motivated by a phase III clinical trial in multiple sclerosis, we develop a semiparametric frailty modelling approach to estimate time-varying effects for overdispersed recurrent events data with treatment switching. The proposed model incorporates the treatment switching time in the time-varying coefficients. Theoretical properties of the proposed model are established and an efficient expectation-maximization algorithm is derived to obtain the maximum likelihood estimates. Simulation studies evaluate the numerical performance of the proposed model under various temporal treatment effect curves. The ideas in this paper can also be used for time-varying coefficient frailty models without treatment switching as well as for alternative models when the proportional hazard assumption is violated. A multiple sclerosis dataset is analysed to illustrate our methodology

Die Gefäßchirurgie in der Schweiz - derzeitiger Stand und Ausblick: Vascular surgery in Switzerland - Current situation and perspectives

Zusammenfassung: Die Gefäßchirurgie hat sich angesichts der demografischen Entwicklung, des Spezialisierungsdrucks und einer Vielzahl an technischen Innovationen in den letzten beiden Jahrzehnte sehr dynamisch entwickelt. Die Autonomisierung innerhalb der Chirurgie (mit umgekehrt transdisziplinärem Zusammenwachsen mit nichtchirurgischen Spezialgebieten), das wachsende Behandlungsspektrum der endovaskulären Intervention, veränderte Patientenpfade und die zunehmende Globalisierung des medizinischen Umfelds prägen die aktuellen Trends in Europa. Dieser Artikel beleuchtet die derzeitige spital- und standespolitische Situation der Gefäßchirurgie in der Schweiz und identifiziert die wichtigsten nationalen Herausforderungen in den Bereichen Weiterbildung und Standespolitik, Demografie und Gesundheitsversorgung, Forschung und Qualitätskontrolle. Im europäischen Vergleich ist der schweizerische Weg zum Gefäßchirurgen aufwendig und langwierig, was seine Konkurrenzfähigkeit einschränkt. Ziel muss es sein, die Schweizer Gefäßchirurgie vermehrt auf die klinischen und akademischen Bedürfnisse einer unabhängigen Spezialität auszurichten. Mögliche Lösungsansätze werden diskutiert und Zukunftsaussichten skizzier

CO17 107. Experiencia inicial con la prótesis de válvula aórtica sin sutura 3f-enable de segunda generación

ObjetivosLa válvula aórtica ATS-3F-Enable™ representa una nueva generación con pericardio equino, stent de nitinol autoexpandible e implantación sin suturas. Evaluamos la técnica de implantación, la seguridad y efectividad de la válvula así como los resultados al año de implantación.Material y métodosAnálisis de resultados en una serie de 27 pacientes consecutivos con estenosis de válvula aórtica y reemplazamiento aislado de la válvula por una ATS-3F-Enable™ entre agosto de 2007 y febrero de 2009. La edad media fue 75,7±6,6 años. Diecisiete mujeres (63%). EuroSCORE mediano: 8, y medio: 7,1±1,7.ResultadosEl tamaño medio de válvula implantada fue de 23mm (franja: 19-27mm). La media de tiempo de clampaje aórtico fue de 39,8±15min (franja: 29-103min). La media de tiempo de circulación extracorpórea fue de 58,6±20min (franja: 41-127). La media de tiempo de hospitalización fue de 11 días (7-22). No hubo mortalidad durante la intervención. Al alta, los gradientes de presión transvalvular medio y alto con ecocardiografía fueron de 11,6 y 18,5mmHg, respectivamente. Dos pacientes presentaron una fuga paravalvular moderada y un paciente fue reoperado a causa de una fuga paravalvular grave. Se requirió la implantación de marcapasos en cinco pacientes (18,5%). El seguimiento al cabo de 1 año fue del 100% y la supervivencia fue del 86%.ConclusionesLa prótesis aórtica ATS-3F-Enable™ puede ser implantada con seguridad y presenta resultados hemodinámicos favorables. El stent autoexpandible y la técnica sin sutura permite una implantación rápida, sin embargo, no tan rápida como esperado. Acumulación de experiencia y algunas modificaciones en el diseño de la prótesis podrán ayudar a perfeccionar la técnica

Gefäßmedizin heute: Die Berner Sicht

Zusammenfassung: Die moderne Behandlung von Gefäßpatienten stellt eine reizvolle und anspruchsvolle Aufgabe dar, welche aufgrund der Komplexität und der Breite des Spektrums heute in interdisziplinären Gefäßzentren durchgeführt werden sollte. Die enge Zusammenarbeit zwischen Gefäßchirurgen und Angiologen hat an der Universität Bern eine lange Tradition. Der vorliegende Artikel legt die grundlegende Philosophie unserer gefäßchirurgisch-angiologischen Freundschaft und Zusammenarbeit dar und schildert deren Umsetzung im klinischen Allta

Interactions between the night time valley-wind system and a developing cold-air pool

This is a pre-copyedited, author-produced PDF of an article accepted for publication in Boundary-Layer Meteorology following peer review. The version of record [Arduini, G., Staquet, C & Chemel, C., ‘Interactions between the night time valley-wind system and a developing cold-air pool’, Boundary-Layer Meteorol (2016) 161:1 (49-72), first published online June 2, 2016, is available at Springer online at doi: 10.1007/s10546-016-0155-8The Weather Research and Forecast (WRF) numerical model is used to characterize the influence of a thermally-driven down-valley flow on a developing cold-air pool in an idealized alpine valley decoupled from the atmosphere above. Results for a three-dimensional (3D) valley, which allows for the formation of a down-valley flow, and for a two-dimensional (2D) valley, where the formation of a down-valley flow is inhibited, are analyzed and compared. A key result is that advection leads to a net cooling in the 2D valley and to a warming in the 3D valley, once the down-valley flow is fully developed. This difference stems from the suppression of the slope-flow induced upward motions over the valley centre in the 3D valley. As a result, the downslope flows develop a cross-valley circulation within the cold-air pool, the growth of the cold-air pool is reduced and the valley atmosphere is generally warmer than in the 2D valley. A quasi-steady state is reached for which the divergence of the down-valley flow along the valley is balanced by the convergence of the downslope flows at the top of the cold-air pool, with no net contribution of subsiding motions far from the slope layer. More precisely, the inflow of air at the top of the cold-air pool is found to be driven by an interplay between the return flow from the plain region and subsidence over the plateaux. Finally, the mechanisms that control the structure of the cold-air pool and its evolution are found to be independent of the valley length as soon as the quasi-steady state is reached and the down-valley flow is fully developed.Peer reviewedFinal Accepted Versio

Weekly low-dose treatment with intravenous iron sucrose maintains iron status and decreases epoetin requirement in iron-replete haemodialysis patients

Background. Haemodialysis patients need sustained treatment with intravenous iron because iron deficiency limits the efficacy of recombinant human epoetin therapy in these patients. However, the optimal intravenous iron maintenance dose has not been established yet. Methods. We performed a prospective multicentre clinical trial in iron-replete haemodialysis patients to evaluate the efficacy of weekly low-dose (50 mg) intravenous iron sucrose administration for 6 months to maintain the iron status, and to examine the effect on epoetin dosage needed to maintain stable haemoglobin values in these patients. Fifty patients were enrolled in this prospective, open-label, single arm, phase IV study. Results. Forty-two patients (84%) completed the study. After 6 months of intravenous iron sucrose treatment, the mean ferritin value showed a tendency to increase slightly from 405 ± 159 at baseline to 490 ± 275 µg/l at the end of the study, but iron, transferrin levels and transferrin saturation did not change. The haemoglobin level remained stable (12 ± 1.1 at baseline and 12.1 ± 1.5 g/dl at the end of the study). The mean dose of darbepoetin alfa could be reduced from 0.75 to 0.46 µg/kg/week; epoetin alfa was decreased from 101 to 74 IU/kg/week; and the mean dose of epoetin beta could be reduced from 148 to 131 IU/kg/week at the end of treatment. Conclusions. A regular 50 mg weekly dosing schedule of iron sucrose maintains stable iron stores and haemoglobin levels in haemodialysed patients and allows considerable dose reductions for epoetins. Low-dose intravenous iron therapy may represent an optimal approach to treat the continuous loss of iron in dialysis patient

Optimal Risk Transfers in Insurance Groups

Optimal risk transfers are derived within an insurance group consisting of two separate legal entities, operating under potentially different regulatory capital requirements and capital costs. Consistent with regulatory practice, capital requirements for each entity are computed by either a value-at-risk or an expected shortfall risk measure. The optimality criterion consists of minimising the risk-adjusted value of the total group liabilities, with valuation carried out using a cost-of-capital approach. The optimisation problems are analytically solved and it is seen that optimal risk transfers often involve the transfer of tail risk (unlimited reinsurance layers) to the more weakly regulated entity. We show that, in the absence of a capital requirement for the credit risk that specifically arises from the risk transfer, optimal risk transfers achieve capital efficiency at the cost of increasing policyholder deficit. However, when credit risk is properly reflected in the capital requirement, incentives for tail-risk transfers vanish and policyholder welfare is restored

Inactivity of nitric oxide synthase gene in the atherosclerotic human carotid artery

Objective : Nitric oxide (NO) inhibits thrombus formation, vascular contraction, and smooth muscle cell proliferation. We investigated whether NO release is enhanced after endothelial NO synthase (eNOS) gene transfer in atherosclerotic human carotid artery ex vivo. Methods and Results : Western blotting and immunohistochemistry revealed that transduction enhanced eNOS expression; however, neither nitrite production nor NO release measured by porphyrinic microsensor was altered. In contrast, transduction enhanced NO production in non-atherosclerotic rat aorta and human internal mammary artery. In transduced carotid artery, calcium-dependent eNOS activity was minimal and did not differ from control conditions. Vascular tetrahydrobiopterin concentrations did not differ between the experimental groups.Treatment of transduced carotid artery with FAD, FMN, NADPH, L-arginine, and either sepiapterin or tetrahydrobiopterin did not alter NO release. Superoxide formation was similar in transduced carotid artery and control. Treatment of transduced carotid artery with superoxide dismutase (SOD), PEG-SOD, PEG-catalase did not affect NO release. Conclusions : eNOS transduction in atherosclerotic human carotid artery results in high expression without any measurable activity of the recombinant protein. The defect in the atherosclerotic vessels is neither caused by cofactor deficiency nor enhanced NO breakdown. Since angioplasty is performed in atherosclerotic arteries,eNOS gene therapy is unlikely to provide clinical benefi