Problems in diagnosis and surgical treatment of the retroperitoneal non-pancreatogenic phlegmons

Catedra de Chirurgie, FEC MF, Universitatea de Stat de Medicină și Farmacie ”N. Testemițanu”, Chișinău, Moldova, Al XI-lea Congres al Asociației Chirurgilor „Nicolae Anestiadi” din Republica Moldova și cea de-a XXXIII-a Reuniune a Chirurgilor din Moldova „Iacomi-Răzeșu” 27-30 septembrie 2011Supurațiile ale spațiului retroperitoneal sunt o problemă medico-chirurgicală neobișnuită cu un tablou clinic vag, care prezintă o provocare în aprecierea diagnosticului. Debutul insidios și evoluție ocultă ale acestei patologii sunt urmate de un diagnostic întârziat și drenaj neadecvat, astfel pentru flegmon retroperitoneal sunt caracteristice morbiditatea și mortalitatea considerabile. Anterior au fost publicate studii privind detaliile anatomice ale spațiilor extraperitoneale, dar mai puțina atenție a fost acordată metodelor de diagnostic și tehnicilor chirurgicale de drenaj. Prezentăm o trecere în revistă a 15 de cazuri de inflamații suruprative retroperitoneale nonpancreatogene care s-au manifestat ca entitate clinică principală. În aspect etiologic pacienții s-au repartizat în 5 grupe: psoitele purulente – 4, abcesele retroperitoneale apendiculare - 4, perinefritele purulente - 3, colecții retroperitoneale în urma osteolizei - 3 (ostemielita hematogenă, postraumatică, tuberculoza osoasă), hematom postraumatic retroperitoneal infectat – 1 caz. Trei pacienți (16,7 %) au decedat în perioada postoperatorie precoce. Complicații au survenit la 40 % pacienți. Letalitatea și rata înaltă de complicații au fost asociate cu perioada îndelungată de la debut până la diagnostic pozitiv (> 5 zile) și cu hemocultura pozitivă. Există o corelație între tipuri de complicații și sursa de infecție retroperitoneală. Computer tomografia este metoda cea mai informativă în diagnosticul supurațiilor abdominale extraperitoneale. În cazuri selecte drenajul ecoghidat poate fi folosit ca un gest chirurgical inițial. Descriem tehnica operatorie în dependență de topografia procesului purulent retroperitoneal. Este propus un plan de diagnostic și tratament pentru fiecare grup etiologic.Retroperitoneal space inflammation is an unusual surgical problem with vague clinical presentation, which presents a diagnostic challenge. An insidious onset and occult evolution of illness marked by diagnostic delay, inadequate drainage, and considerable morbidity and mortality is common. Papers regarding anatomic detailing of the extraperitoneal spaces have been published, but less attention has been focused on diagnostic and drainage techniques.We report an analysis of 15 cases of retroperitoneal suppurations which acted as main clinical manifestation. According to etiology of inflammation patients were distributed into 5 groups: psoas abscesses – 4 cases, retroperitoneal appendical abscesses – 4 cases, purulent perinephritis -3, retroperitoneal collections caused by osteolysis – 3 patients (hematogenic, posttraumatic or tuberculous) and one case of infected posttraumatic hematoma.Three patients (16,7 %) died in the early postoperative period. Rate of complications was 40 %. High lethality and postoperative morbidity were associated with positive blood cultures and delayed diagnosis (> 5 days). There is a correlation between the type of complications and etiology of the retroperitoneal phlegmon. Computed tomography is the most informative diagnostic method for the extraperitoneal purulent collections. Echoguided drainage in selected cases appears to be a useful initial approach. The operative technique dependent on the retroperitoneal purulent collection topography is described. A diagnostic and treatment plan is proposed for each etiologic group

Intraperitoneal single-layer and double-layer polypropylene mesh integrated in rectus abdominis sheath in repair of large and recurrent incisional hernias

Chirurgie generală, Spitalul Clinic Republican, Chișinău, Moldova, Al XI-lea Congres al Asociației Chirurgilor „Nicolae Anestiadi” din Republica Moldova și cea de-a XXXIII-a Reuniune a Chirurgilor din Moldova „Iacomi-Răzeșu” 27-30 septembrie 2011Introducere. În tratamentul chirurgical al eventrațiilor postoperatorii mari și recidivante au fost aplicate diferite tehnici de plastii cu utilizarea materialelor sintetice, care au scopul de a reduce substanțial rată de recidive. Prezentăm o tehnică nouă de plastie cu plasă din polipropilen.Materiale şi metode. Panglicile 3-4 cm lungime sunt croite din marginile plasei. Omentul se fixează la distanța de marginea defectului de foița peritoneală parietală acoperind viscerele. Plasa se poziționează intraperitoneal. În plastia într-un plan panglicele plasei se trec bont prin marginea laterală a muşchiului rect abdominal. În plastie în două planuri panglicile plasei din al doilea stat se trec bont la mijlocul mușchilor recți abdominali. Capetele exteriorizate ale plasei ancorează pe suprafața tecii anterioare a recților abdominali. Utilizând această metodică au fost operați 116 pacienți cu eventrații postoperatorii mari în perioada februarie 2005 şi aprilie 2010 (65 pacienți cu eventrații recidivante). Complicațiile intra- şi postoperatorii au fost întregistrate prospectiv şi analizate retrospectiv.Rezultate. Recidive de eventrații, complicații gastrointestinale, fistule intestinale sau decese nu au fost înregistrate în perioada de urmărire. Seroamele ale plăgilor postoperatorii au fost înregistrate la 12 (10,34 %) pacienți. Nici un pacient nu a avut supurația plăgii postoperatorii. Concluzii. Tehnica propusă prezintă o alternativă sigură şi realizabilă pentru pacienți cu eventrații mari şi recidivante. Această metodă exclude posibilitatea de migrare a plasei din locul de inserție, scade rata de recidive şi nu este asociată cu complicații serioase.Background. There are different techniques of incisional hernia repair using prosthetic materials, which have lowered the recurrence rate. We present a new method of incisional hernia surgery using polypropylene mesh. Methods and materials. Stripes 3-4 cm long are cut out at the margins of the polypropylene mesh. Then the mash is placed intraperitoneally upon the greater omentum, fixed thoroughly to the anterior abdominal wall. Prepared stripes are bluntly guided through the lateral margins of the rectus abdominis muscle and fasten to the anterior wall of the rectus abdominis sheath. In the double-layer variant strips from the second layer of the mesh are guided through the middle of the rectus abdominis. Using this technique we performed 116 open abdominal wall incisional hernia repairs between February 2005 and April 2010 (65 of them with recurrent hernia). Intra- and postoperative complications were registered prospectively and retrospectively analyzed. Results. There were no hernia recurrences during the follow-up period, gastrointestinal complications, fistulas, or deaths. Seromas occurred postoperatively in 5 patients (8,9%). None of the patients developed surgical site infections. Conclusions. The proposed technique is a safe and feasible alternative procedure in patients with large primary or recurrent incisional hernias. This method completely excludes the possibility of migration of the mesh from the place of insertion, reduces the rate of recurrence, and is not associated with serious complications

Simultaneous dynamic electrical and structural measurements of functional materials

A new materials characterization system developed at the XMaS beamline, located at the European Synchrotron Radiation Facility in France, is presented. We show that this new capability allows to measure the atomic structural evolution (crystallography) of piezoelectric materials whilst simultaneously measuring the overall strain characteristics and electrical response to dynamically (ac) applied external stimuli

Springback of stamping process optimization using response surface methodology and interval computation

In manufacturing process, the quality of final products is significantly affected by both product design and process variables. However, historically tolerance research primarily focused on allocating tolerances based on product design characteristics of each component. This work proposes to expand the current tolerancing practices, and presents a new optimization method of tolerancing mechanical systems using interval computation for the prediction of system response. The proposed methodology is based on the development and integration of three concepts in process optimization: mechanical tolerancing, response surface methodology, and interval computation method. An industry case study is used to illustrate the proposed approach

Symbolic-Numeric Algorithms for Computer Analysis of Spheroidal Quantum Dot Models

A computation scheme for solving elliptic boundary value problems with axially symmetric confining potentials using different sets of one-parameter basis functions is presented. The efficiency of the proposed symbolic-numerical algorithms implemented in Maple is shown by examples of spheroidal quantum dot models, for which energy spectra and eigenfunctions versus the spheroid aspect ratio were calculated within the conventional effective mass approximation. Critical values of the aspect ratio, at which the discrete spectrum of models with finite-wall potentials is transformed into a continuous one in strong dimensional quantization regime, were revealed using the exact and adiabatic classifications.Comment: 6 figures, Submitted to Proc. of The 12th International Workshop on Computer Algebra in Scientific Computing (CASC 2010) Tsakhkadzor, Armenia, September 5 - 12, 201

Unified treatment of spin torques using a coupled magnetisation dynamics and three-dimensional spin current solver

A three-dimensional spin current solver based on a generalised spin drift-diffusion description, including the bulk and interfacial spin Hall effects, is integrated with a magnetisation dynamics solver. The resulting model is shown to simultaneously reproduce the spin-orbit torques generated using the spin Hall effect, spin pumping torques generated by magnetisation dynamics in multilayers, as well as the spin transfer torques acting on magnetisation regions with spatial gradients, whilst field-like and spin-like torques are reproduced in a spin valve geometry. Two approaches to modelling interfaces are analysed, one based on the spin mixing conductance and the other based on continuity of spin currents where the spin dephasing length governs the absorption of transverse spin components. In both cases analytical formulas are derived for the spin-orbit torques in a heavy metal / ferromagnet bilayer geometry, showing in general both field-like and damping-like torques are generated. The limitations of the analytical approach are discussed, showing that even in a simple bilayer geometry, due to the non-uniformity of the spin currents, a full three-dimensional treatment is required. The model is further applied to the analysis of the spin Hall angle in Pt by reproducing published experimental ferromagnetic resonance data in the bilayer geometry

Temperature dependence of capture coefficients in trapping phenomena

The temperature dependence of the capture coefficients in trapping phenomena is investigated. It is proved that, besides the dependence induced by the thermal velocity of the carriers, the stress-induced traps at the interfaces of the multi-layered structures present a supplementary temperature dependence. This dependence is found to be of Gaussian type and is in a good agreement with the experimental results. © 2010 IEEE

Domain-wall pinning, nonadiabatic spin-transfer torque, and spin-current polarization in permalloy wires doped with vanadium

Copyright © 2010 The American Physical SocietyUsing pulsed-current measurements we investigate the domain-wall depinning via spin-transfer torque from pinning potentials in V-doped Ni80Fe20 wires. The domain-wall depinning boundary, showing the variation of threshold current density with longitudinal magnetic field is measured and reproduced using micromagnetic simulations. This method allows us to determine the spin-current polarization and nonadiabaticity parameter in these materials. By increasing the V concentration we show that the nonadiabaticity parameter is increased while the Gilbert damping is unaffected. On the other hand the spin-current polarization is decreased, resulting in larger threshold current densities

Stress-induced traps in multilayered structures

The trap parameters of defects in Si/CaF2 multilayered structures were determined from the analysis of optical charging spectroscopy measurements. Two kinds of maxima were observed. Some of them were rather broad, corresponding to "normal" traps, while the others, very sharp, were attributed to stress-induced traps. A procedure of optimal linear smoothing the noisy experimental data has been developed and applied. This procedure is based on finding the minimal value of the relative error with respect to the value of the smoothing window. In order to obtain a better accuracy for the description of the trapping-detrapping process, a Gaussian temperature dependence of the capture crosssections characterizing the stress-induced traps was introduced. Both the normal and the stress-induced traps have been characterized, including some previously considered as only noise features.Comment: 37 pages, 9 figure

Stress-induced traps in multilayered structures

The trap parameters of defects in Si/CaF 2 multilayered structures were determined from the analysis of optical charging spectroscopy measurements. Two kinds of maxima were observed. Some of them were rather broad, corresponding to "normal" traps, while the others, very sharp, were attributed to stress-induced traps. A procedure of optimal linear smoothing the noisy experimental data has been developed and applied. This procedure is based on finding the minimal value of the relative error with respect to the value of the smoothing window. In order to obtain a better accuracy for the description of the trapping-detrapping process, a Gaussian temperature dependence of the capture cross-sections characterizing the stress-induced traps was introduced. Both the normal and the stress-induced traps have been characterized, including some previously considered as only noise features. ©2011 American Institute of Physics