Malignant infarction of the middle cerebral artery in a porcine model. A pilot study

Animal models; Central nervous system; InfarctionModels animals; Sistema nerviós central; InfartModelos animales; Sistema nervioso central; InfartoBackground and purpose Interspecies variability and poor clinical translation from rodent studies indicate that large gyrencephalic animal stroke models are urgently needed. We present a proof-of-principle study describing an alternative animal model of malignant infarction of the middle cerebral artery (MCA) in the common pig and illustrate some of its potential applications. We report on metabolic patterns, ionic profile, brain partial pressure of oxygen (PtiO2), expression of sulfonylurea receptor 1 (SUR1), and the transient receptor potential melastatin 4 (TRPM4). Methods A 5-hour ischemic infarct of the MCA territory was performed in 5 2.5-to-3-month-old female hybrid pigs (Large White x Landrace) using a frontotemporal approach. The core and penumbra areas were intraoperatively monitored to determine the metabolic and ionic profiles. To determine the infarct volume, 2,3,5-triphenyltetrazolium chloride staining and immunohistochemistry analysis was performed to determine SUR1 and TRPM4 expression. Results PtiO2 monitoring showed an abrupt reduction in values close to 0 mmHg after MCA occlusion in the core area. Hourly cerebral microdialysis showed that the infarcted tissue was characterized by reduced concentrations of glucose (0.03 mM) and pyruvate (0.003 mM) and increases in lactate levels (8.87mM), lactate-pyruvate ratio (4202), glycerol levels (588 μM), and potassium concentration (27.9 mmol/L). Immunohistochemical analysis showed increased expression of SUR1-TRPM4 channels. Conclusions The aim of the present proof-of-principle study was to document the feasibility of a large animal model of malignant MCA infarction by performing transcranial occlusion of the MCA in the common pig, as an alternative to lisencephalic animals. This model may be useful for detailed studies of cerebral ischemia mechanisms and the development of neuroprotective strategies.The Neurotraumatology and Neurosurgery Research Unit is supported by a grant from the Departament d'Universitats, Recerca i Societat de la Informació de la Generalitat de Catalunya (SGR 2014-844). This work has been supported in part by the Fondo de Investigación Sanitaria (Instituto de Salud Carlos III) with grant FIS PI11/00700, which was co-financed by the European Regional Development Fund (ERDF) and awarded to Dr. J. Sahuquillo. A. Sánchez-Guerrero is the recipient of a personal pre-doctoral grant from the Instituto de Salud Carlos III (grant number grant number FI12/00074)

Base de datos multicéntrica de hemorragia subaracnoidea espontánea del Grupo de Trabajo de Patología Vascular de la Sociedad Española de Neurocirugía: presentación,criterios de inclusión y desarrollo de una base de datos en internet = Spontaneous Subarachnoid Haemorrhage multicenter database from the Group for the Study of Vascular Pathology of the Spanish Society for Neurosurgery: Presentation, inclusion criteria and development of an internet-based registry

Introducción. La hemorragia subaracnoidea (HSA) continúa siendo una de las enfermedades de interés neuroquirúrgico de más alta morbilidad y mortalidad. Su estudio es clave a la hora de mejorar la atención de estos enfermos en nuestro medio. Con este fin el Grupo de Trabajo de Patología Vascular de la SENEC decidió la creación de una base de datos multicéntrica para su estudio. Material y métodos. Se incluyen en esta base de datos todos los casos de hemorragia subaracnoidea espontánea ingresados en los centros participantes de forma prospectiva desde Noviembre del año 2004 hasta Noviembre del 2007. Se decidieron de forma consensuada los campos a recoger incluyendo edad, antecedentes personales, características clínicas, características radiológicas y del aneurisma, tipo de tratamiento y complicaciones de la enfermedad, evolución según la escala de evolución de Glasgow (GOS) al alta y a los seis meses así como el resultado angiográfico del tratamiento. Todos los campos se recogieron en un formulario rellenable a través de una página web segura. Resultados. En los tres años en los que ha estado activa la base se han recogido un total de 1149 casos de HSA espontánea recogidos por 14 centros participantes. Se ha estimado que es necesario aproximadamente un tiempo de 3.4 minutos para rellenar cada caso. En cuanto a sus características generales la serie es similar a otras series hospitalarias no seleccionadas. La edad media de los enfermos incluidos es de unos 55 años y la relación mujer:hombre 4:3. En cuanto a la gravedad del sagrado inicial un 32% de los enfermos se encontraba en mal grado clínico (WFNS = 4 ó 5). El 5% de los pacientes fallecieron antes de realizarse una angiografía que confirmara el origen aneurismático del sangrado. Se confirmó el origen aneurismático en el 76% de los pacientes mientras que en el 19% no se encontró ninguna lesión vascular responsable del sangrado, siendo clasificados como HSA idiopática. En los pacientes en los que se detectó un aneurisma su tratamiento fue endovascular en el 47% de los casos, quirúrgico en el 39, mixto en el 3% y no recibieron tratamiento de su aneurisma el 11% de los pacientes por fallecimiento precoz. En cuanto a su evolución, la mortalidad global de la serie se sitúa en el 22%. Sólo el 40% de los enfermos con HSA aneurismática presentaron una buena evolución (GOS=5). Conclusiones. La HSA espontánea continúa siendo una enfermedad con alta morbilidad y mortalidad. Esta base de datos puede ser un instrumento para conocer mejor sus características en nuestro medio y mejorar sus resultados, ya que se trata de una serie multicéntrica hospitalaria no seleccionada. Sería pues recomendable que esta base constituyera el germen de un registro nacional de HSA espontánea. Introduction. Subarachnoid haemorrhage is one of the most severe neurosurgical diseases. Its study is crucial for improving the care of these patients in our environment. With this goal the Group for the Study of Neurovascular Pathology of the Spanish Society for Neurosurgery (SENEC) decided to create a multicenter registry for the study of this disease. Materials and methods. In this database we have prospectively included all cases with spontaneous subarachnoid haemorrhage admitted to the participant hospitals from November 2004 to November 2007. The fields to be included in the database were selected by consensus, including age, past medical history, clinical characteristics at admission, radiological characteristics including presence or absence of an aneurysm and its size and location, type and complications of the aneurysm treatment, outcome assessed by the Glasgow Outcome Scale (GOS) at discharge and six months after the bleeding as well as the angiographic result of the aneurysm treatment. All fields were collected by means of an electronic form posted in secure web page. Results. During the three years of study a total of 1149 patients have been included by 14 Hospitals. The time needed to fill in a patient in the registry is approximately 3.4 minutes. This series of patients with spontaneous SAH is similar to other non-selected in-hospital series of SAH. The mean age of the patients is 55 years and there is a 4:3 female to male ratio. In relation to the severity of the bleeding 32% of the patients were in poor clinical grade at admission (WFNS 4 or 5). 5% of the patients died before angiography could be performed. An aneurysm was confirmed as the origin of the bleeding in 76% of the patients (aSAH), while in 19% of the patients no lesion was found in the angiographic studies and were thus classified as idiopathic subarachnoid hemorrhage (ISAH). Of those patients with aSAH, 47% were treated endovascularly, 39% surgically, 3% received a combined treatment and 11% did not receive any treatment for their aneurysm because of early death. Regarding outcome, there is a 22% mortality in the series. Only 40% of the patients with aSAH reached a good outcome at discharge (GOS = 5). Conclusions. Spontaneous SAH continues to be a disease with high morbidity and mortality. This database can be an ideal instrument for improving the knowledge about this disease in our environment and to achieve better results. It would be desirable that this database could in the future be the origin of a national registry of spontaneous SAH

Neurosurgical emergency management during the lockdown period in health care regions in Spain with different COVID-19 impact: lessons learned to improve outcomes on the future waves

Background COVID-19 has overloaded health care systems, testing the capacity and response in every European region. Concerns were raised regarding the impact of resources’ reorganization on certain emergency pathology management. The aim of the present study was to assess the impact of the outbreak (in terms of reduction of neurosurgical emergencies) during lockdown in different regions of Spain. Methods We analyzed the impact of the outbreak in four different affected regions by descriptive statistics and univariate comparison with same period of two previous years. These regions differed in their incidence level (high/low) and in the time of excess mortality with respect to lockdown declaration. That allowed us to analyze their influence on the characteristics of neurosurgical emergencies registered for every region. Results 1185 patients from 18 neurosurgical centers were included. Neurosurgical emergencies that underwent surgery dropped 24.41% and 28.15% in 2020 when compared with 2019 and 2018, respectively. A higher reduction was reported for the most affected regions by COVID-19. Non-traumatic spine experienced the most significant decrease in number of cases. Life-threatening conditions did not suffer a reduction in any health care region. Conclusions COVID-19 affected dramatically the neurosurgical emergency management. The most significant reduction in neurosurgical emergencies occurred on those regions that were hit unexpectedly by the pandemic, as resources were focused on fighting the virus. As a consequence, life-threating and non-life-threatening conditions’ mortality raised. Results in regions who had time to prepare for the hit were congruent with an organized and sensible neurosurgical decision-making.Peer reviewe

Aportaciones de la monitorización intraoperatoria de la presión tisular de oxígeno en neurocirugía vascular

La present Tesi Doctoral està composta per quatre articles dirigits a aprofundir en el coneixement de les malalties cerebrovasculars a partir de la monitorització intraoperatòria de la pressió tissular d'oxigen (PtiO2) mitjançant sondes polarogràfiques del tipus Clark. Els estudis que la componen són: • [Detection of episodes of ischemic tissue hypoxia by means of the combined intraoperative neurophysiologic monitoring with the tissue oxygenation monitoring in aneurysm surgery]. Arikan F, Vilalta J, Minoves T, Moncho D, Vilalta A, Noguer M, Ibarra B, Sahuquillo J. Neurosurgery (Astur). 2008 Apr; 19 (2): 113-20. Spanish. ISSN: 1130-1473PMID: 18500409. • Intraoperative monitoring of brain tissue oxygenation during arteriovenous malformation resection. Arikan F, Vilalta J, Noguer M, Olive M, Vidal-Jorge M, J. J Neurosurg Sahuquillo Anesthesiol. 2014 Oct; 26 (4): 328-41. DOI: 10.1097 / ANA. 0000000000000033. PMID: 24492516 • [Intraoperative monitoring of oxygen tissue pressure: Applications in vascular neurosurgery]. Arikan F, Vilalta J, Torne R, Chocron I, Rodriguez-Tesouro A, Sahuquillo J. Neurosurgery (Astur). 2014 Nov-Dec; 25 (6): 275-85. DOI: 10.1016 / j.neucir.2014.03.003. Epub 2014 June 14. Spanish. PMID: 24934513 • Rapid resolution of brain ischemic hypoxia after cerebral revascularization in moyamoya disease. Arikan F, Vilalta J, Torne R, Noguer M, Lorenzo-Bosquet C, Sahuquillo J. Neurosurgery. In press. Accepted on October 27, 2014. DOI: 10.1227 / NEU.0000000000000609 PMID: 25584958. Aquests estudis proporcionen la següent informació clínicament rellevant: 1. La monitorització de la PtiO2 permet detectar d'una forma ràpida i fiable les situacions d'hipòxia cerebral isquèmica intraoperatòria, permetent establir estratègies terapèutiques per a la resolució de la mateixa. La monitorització intraoperatòria contínua de la PtiO2 és una eina útil per reduir les complicacions isquèmiques. 2. La relació PtiO2/PaO2 és un índex superior als valors absoluts de PtiO2 perquè permeten el diagnòstic de la hipòxia tissular quan els valors de PtiO2 són artificialment alts a causa de l'augment de la PaO2 (per exemple, en pacients amb ventilació mecànica). El llindar de referència indicatiu d'hipòxia tissular per a la relació PtiO2/PaO2 és de 0,10 i el llindar indicatiu de hiperòxia tissular de 0,35. 3. La relació PtiO2/PaO2 obtinguda en subjectes sans ens demostra que l'oxigen en el cervell està fortament regulat i que la relació entre la PaO2 i la PtiO2 en el cervell normal acaba aconseguint un altiplà. 4. Confirmem les troballes d'altres autors en què molts pacients amb una malformació arteriovenosa (MAV) presenten una hipòxia cerebral clínicament ben tolerada en el cervell del voltant del nidus malformatiu. Els nostres estudis també demostren que les MAVs poden provocar canvis en l'oxigenació i el metabolisme en zones cerebrals allunyades de l'hemisferi ipsilateral. 5. Gran part dels pacients amb una MAV presenten un patró hipòxic voltant del nidus malformatiu i / o del cervell distant. Aquests patrons hipòxics reverteixen després de la resecció de la MAV. 6. El monitoratge intraoperatòria de la PtiO2 és un mètode fiable i segur per avaluar l'estat de l'oxigenació i permeabilitat del bypass en pacients sotmesos a cirurgia de revascularització cerebral. La hipòxia tissular és gairebé constant en pacients tributaris de cirurgia de revascularització amb malaltia de Moyamoya i reducció de la reserva de perfusió cerebral. 7. La revascularització directa mitjançant la realització d'un bypass entre l'artèria temporal superficial i l'artèria cerebral mitjana produeix un augment ràpid i sostingut de la PtiO2 que reverteixen a valors de normòxia.La presente Tesis Doctoral está compuesta por cuatro artículos dirigidos a profundizar en el conocimiento de las enfermedades cerebrovasculares a partir de la monitorización intraoperatoria de la presión tisular de oxígeno (PtiO2) mediante sondas polarográficas del tipo Clark. Los estudios que la componen son: • [Detection of episodes of ischemic tissue hypoxia by means of the combined intraoperative neurophysiologic monitoring with the tissue oxygenation monitoring in aneurysm surgery]. Arikan F, Vilalta J, Minoves T, Moncho D, Vilalta A, Noguer M, Ibarra B, Sahuquillo J. Neurosurgery (Astur). 2008 Apr; 19 (2): 113-20. Spanish. ISSN: 1130-1473PMID: 18500409. • Intraoperative monitoring of brain tissue oxygenation during arteriovenous malformation resection. Arikan F, Vilalta J, Noguer M, Olive M, Vidal-Jorge M, J. J Neurosurg Sahuquillo Anesthesiol. 2014 Oct; 26 (4): 328-41. DOI: 10.1097 / ANA. 0000000000000033. PMID: 24492516 • [Intraoperative monitoring of oxygen tissue pressure: Applications in vascular neurosurgery]. Arikan F, Vilalta J, Torne R, Chocron I, Rodriguez-Tesouro A, Sahuquillo J. Neurosurgery (Astur). 2014 Nov-Dec; 25 (6): 275-85. DOI: 10.1016 / j.neucir.2014.03.003. Epub 2014 June 14. Spanish. PMID: 24934513 • Rapid resolution of brain ischemic hypoxia after cerebral revascularization in moyamoya disease. Arikan F, Vilalta J, Torne R, Noguer M, Lorenzo-Bosquet C, Sahuquillo J. Neurosurgery. In press. Accepted on October 27, 2014. DOI: 10.1227 / NEU.0000000000000609 PMID: 25584958. Estos estudios proporcionan la siguiente información clínicamente relevante: 1. La monitorización de la PtiO2 permite detectar de una forma rápida y fiable las situaciones de hipoxia cerebral isquémica intraoperatoria, permitiendo establecer estrategias terapéuticas para la resolución de la misma. La monitorización intraoperatoria continua de la PtiO2 es una herramienta útil para reducir las complicaciones isquémicas. 2. La relación PtiO2/PaO2 es un índice superior a los valores absolutos de PtiO2 porque permiten el diagnóstico de la hipoxia tisular cuando los valores de PtiO2 son artificialmente altos debido al aumento de la PaO2 (por ejemplo, en pacientes con ventilación mecánica). El umbral de referencia indicativo de hipoxia tisular para la relación PtiO2/PaO2 es de 0,10 y el umbral indicativo de hiperoxia tisular de 0,35. 3. La relación PtiO2/PaO2 obtenida en sujetos sanos nos demuestra que el oxígeno en el cerebro está fuertemente regulado y que la relación entre la PaO2 y la PtiO2 en el cerebro normal acaba alcanzando una meseta. 4. Confirmamos los hallazgos de otros autores en que muchos pacientes con una malformación arteriovenosa (MAV) presentan una hipoxia cerebral clínicamente bien tolerada en el cerebro de alrededor del nidus malformativo. Nuestros estudios también demuestran que las MAVs pueden provocar cambios en la oxigenación y el metabolismo en zonas cerebrales alejadas del hemisferio ipsilateral. 5. Gran parte de los pacientes con una MAV presentan un patrón hipóxico alrededor del nidus malformativo y/o del cerebro distante. Estos patrones hipóxicos revierten tras la resección de la MAV. 6. La monitorización intraoperatoria de la PtiO2 es un método fiable y seguro para evaluar el estado de la oxigenación y permeabilidad del bypass en pacientes sometidos a cirugía de revascularización cerebral. La hipoxia tisular es casi constante en pacientes tributarios de cirugía de revascularización con enfermedad de Moyamoya y reducción de la reserva de perfusión cerebral. 7. La revascularización directa mediante la realización de un bypass entre la arteria temporal superficial y la arteria cerebral media produce un aumento rápido y sostenido de la PtiO2 que revierten a valores de normoxia.This doctoral thesis consists of four articles that provide new and relevant information about cerebrovascular diseases obtained from intraoperative monitoring of tissue oxygen pressure (PtiO2) using Clark-type polarographic probes. The studies that comprise this thesis are listed below. • [Detection of episodes of ischemic tissue hypoxia by means of the combined intraoperative neurophysiologic monitoring with the tissue oxygenation monitoring in aneurysm surgery]. Arikan F, Vilalta J, Minoves T, Moncho D, Vilalta A, Noguer M, Ibarra B, Sahuquillo J. Neurosurgery (Astur). 2008 Apr; 19 (2): 113-20. Spanish. ISSN: 1130-1473PMID: 18500409. • Intraoperative monitoring of brain tissue oxygenation during arteriovenous malformation resection. Arikan F, Vilalta J, Noguer M, Olive M, Vidal-Jorge M, J. J Neurosurg Sahuquillo Anesthesiol. 2014 Oct; 26 (4): 328-41. DOI: 10.1097 / ANA. 0000000000000033. PMID: 24492516 • [Intraoperative monitoring of oxygen tissue pressure: Applications in vascular neurosurgery]. Arikan F, Vilalta J, Torne R, Chocron I, Rodriguez-Tesouro A, Sahuquillo J. Neurosurgery (Astur). 2014 Nov-Dec; 25 (6): 275-85. DOI: 10.1016 / j.neucir.2014.03.003. Epub 2014 June 14. Spanish. PMID: 24934513 • Rapid resolution of brain ischemic hypoxia after cerebral revascularization in moyamoya disease. Arikan F, Vilalta J, Torne R, Noguer M, Lorenzo-Bosquet C, Sahuquillo J. Neurosurgery. In press. Accepted on October 27, 2014. DOI: 10.1227 / NEU.0000000000000609 PMID: 25584958. These studies provide the clinically relevant information outlined below. 1. Monitoring PtiO2 allows for immediate and reliable detection of ischemic cerebral hypoxia caused by surgical technique and may be used to develop strategies to manage this condition. 2. Continuous monitoring of PtiO2 can be used to quickly and reliably detect situations of intraoperative cerebral ischemic hypoxia and establish therapeutic strategies to resolve it. Continuous intraoperative monitoring of PtiO2 is a useful tool for reducing ischemic complications. 3. The PtiO2/PaO2 ratio is a better index than absolute PtiO2 because it detects hypoxia when absolute values are artifactually high due to increased PaO2 (e.g. patients under mechanical ventilation). The lower reference threshold indicative of tissue hypoxia for the PtiO2/PaO2 ratio is 0.10. The upper reference threshold indicative of tissue hyperoxia for PtiO2/PaO2 is 0.35. 4. PtiO2 / PaO2 ratios obtained in healthy subjects show that oxygen in the brain is heavily regulated and that the relationship between PaO2 and PtiO2 in the normal brain reaches a plateau. 5. The findings of other authors are confirmed by the finding that many patients with AVM present clinically well-tolerated hypoxia in the brain around the nidus. AVMs can cause changes in oxygenation and metabolism in remote areas of the ipsilateral cerebral hemisphere. 6. Many patients with AVM have a hypoxic pattern around the malformation nidus and/or the distant brain. These hypoxic patterns reverse after resection of the AVM. 7. Intraoperative monitoring of PtiO2 is a safe and reliable method to determine brain oxygenation status and patency of bypass in patients undergoing surgery for cerebral revascularization. Tissue hypoxia is almost constant in patients with moyamoya disease and those with a reduction of cerebral perfusion reserve. 8. Direct superficial temporal artery to middle cerebral artery bypass revascularization produces a rapid and sustained increase in PtiO2 and achieves values consistent with normoxia

Functional and clinical evaluation of renal injury in patients treated with adjuvant chemoradiotherapy for gastric cancer: Low dose and comorbidity considerations

Aim: To analyze the dosimetric factors affecting long-term renal function in patients with gastric cancer following postoperative radiotherapy with concomitant chemotherapy to the upper abdomen. Methods: Between January 2005 and July 2010, 13 patients treated with three-dimensional conformal radiotherapy and concurrent fluorouracil-based chemotherapy (CRT) were included in this analysis. After a median follow-up of 55 months, creatinine, glomerular filtration rate (GFR), total kidney and left kidney volumes, before and after CRT and mercaptoacetyltriglycine (MAG3) scintigraphy, were used to evaluate the renal function and were correlated with the dosimetrics data. Results: Significant correlations were found in the loss of left kidney volume and V35 (20.6%) (p = 0.035) and V40 (15.7%) (p = 0.031) and in the loss of relative functional contribution of the main kidney and V35 Gy (p = 0.027) and V40 Gy (p = 0.019). In patients with a slightly low basal GFR (n = 6), the relative functional contribution of the left kidney significantly decreased, regardless of the dosage. Conclusion: Functional renal impairment without any clinical signs or symptoms can be observed in low doses after radiotherapy. Careful treatment planning and a detailed evaluation of the functional renal capacity before treatment may help to reduce late renal toxicity. Copyright (C) 2015, The Egyptian Society of Radiation Sciences and Applications. Production and hosting by Elsevier B.V

Elasto-Plastic Stress Analysis in a Ductile Adhesive & Aluminum Adherends

In this study, an elasto-plastic stress analysis is proposed in an aluminum adherend and a ductile adhesive. Elasto-plastic analysis was carried out for the aluminum adherend and DP460 ductile adhesive in a double-lap joint. The analytical solution was compared with the finite element solution. ANSYS 12 was used in the stress analysis. The analytical solution was performed for the one-dimensional case in the adhesive and the adherends. A FEM solution was given for the two-dimensional case. Similar results were obtained for both. In addition, the solution was carried out for brittle and ductile materials. The mechanical properties of the loctite were nearly the same as the ductile DP460 adhesive. It was observed that the ductile adhesive increased the strength of the structure due to the small shear stresses at the free ends of the adhesive

Aportaciones de la monitorización intraoperatoria de la presión tisular de oxígeno en neurocirugía vascular

La present Tesi Doctoral està composta per quatre articles dirigits a aprofundir en el coneixement de les malalties cerebrovasculars a partir de la monitorització intraoperatòria de la pressió tissular d'oxigen (PtiO2) mitjançant sondes polarogràfiques del tipus Clark. Els estudis que la componen són: • [Detection of episodes of ischemic tissue hypoxia by means of the combined intraoperative neurophysiologic monitoring with the tissue oxygenation monitoring in aneurysm surgery]. Arikan F, Vilalta J, Minoves T, Moncho D, Vilalta A, Noguer M, Ibarra B, Sahuquillo J. Neurosurgery (Astur). 2008 Apr; 19 (2): 113-20. Spanish. ISSN: 1130-1473PMID: 18500409. • Intraoperative monitoring of brain tissue oxygenation during arteriovenous malformation resection. Arikan F, Vilalta J, Noguer M, Olive M, Vidal-Jorge M, J. J Neurosurg Sahuquillo Anesthesiol. 2014 Oct; 26 (4): 328-41. DOI: 10.1097 / ANA. 0000000000000033. PMID: 24492516 • [Intraoperative monitoring of oxygen tissue pressure: Applications in vascular neurosurgery]. Arikan F, Vilalta J, Torne R, Chocron I, Rodriguez-Tesouro A, Sahuquillo J. Neurosurgery (Astur). 2014 Nov-Dec; 25 (6): 275-85. DOI: 10.1016 / j.neucir.2014.03.003. Epub 2014 June 14. Spanish. PMID: 24934513 • Rapid resolution of brain ischemic hypoxia after cerebral revascularization in moyamoya disease. Arikan F, Vilalta J, Torne R, Noguer M, Lorenzo-Bosquet C, Sahuquillo J. Neurosurgery. In press. Accepted on October 27, 2014. DOI: 10.1227 / NEU.0000000000000609 PMID: 25584958. Aquests estudis proporcionen la següent informació clínicament rellevant: 1. La monitorització de la PtiO2 permet detectar d'una forma ràpida i fiable les situacions d'hipòxia cerebral isquèmica intraoperatòria, permetent establir estratègies terapèutiques per a la resolució de la mateixa. La monitorització intraoperatòria contínua de la PtiO2 és una eina útil per reduir les complicacions isquèmiques. 2. La relació PtiO2/PaO2 és un índex superior als valors absoluts de PtiO2 perquè permeten el diagnòstic de la hipòxia tissular quan els valors de PtiO2 són artificialment alts a causa de l'augment de la PaO2 (per exemple, en pacients amb ventilació mecànica). El llindar de referència indicatiu d'hipòxia tissular per a la relació PtiO2/PaO2 és de 0,10 i el llindar indicatiu de hiperòxia tissular de 0,35. 3. La relació PtiO2/PaO2 obtinguda en subjectes sans ens demostra que l'oxigen en el cervell està fortament regulat i que la relació entre la PaO2 i la PtiO2 en el cervell normal acaba aconseguint un altiplà. 4. Confirmem les troballes d'altres autors en què molts pacients amb una malformació arteriovenosa (MAV) presenten una hipòxia cerebral clínicament ben tolerada en el cervell del voltant del nidus malformatiu. Els nostres estudis també demostren que les MAVs poden provocar canvis en l'oxigenació i el metabolisme en zones cerebrals allunyades de l'hemisferi ipsilateral. 5. Gran part dels pacients amb una MAV presenten un patró hipòxic voltant del nidus malformatiu i / o del cervell distant. Aquests patrons hipòxics reverteixen després de la resecció de la MAV. 6. El monitoratge intraoperatòria de la PtiO2 és un mètode fiable i segur per avaluar l'estat de l'oxigenació i permeabilitat del bypass en pacients sotmesos a cirurgia de revascularització cerebral. La hipòxia tissular és gairebé constant en pacients tributaris de cirurgia de revascularització amb malaltia de Moyamoya i reducció de la reserva de perfusió cerebral. 7. La revascularització directa mitjançant la realització d'un bypass entre l'artèria temporal superficial i l'artèria cerebral mitjana produeix un augment ràpid i sostingut de la PtiO2 que reverteixen a valors de normòxia.La presente Tesis Doctoral está compuesta por cuatro artículos dirigidos a profundizar en el conocimiento de las enfermedades cerebrovasculares a partir de la monitorización intraoperatoria de la presión tisular de oxígeno (PtiO2) mediante sondas polarográficas del tipo Clark. Los estudios que la componen son: • [Detection of episodes of ischemic tissue hypoxia by means of the combined intraoperative neurophysiologic monitoring with the tissue oxygenation monitoring in aneurysm surgery]. Arikan F, Vilalta J, Minoves T, Moncho D, Vilalta A, Noguer M, Ibarra B, Sahuquillo J. Neurosurgery (Astur). 2008 Apr; 19 (2): 113-20. Spanish. ISSN: 1130-1473PMID: 18500409. • Intraoperative monitoring of brain tissue oxygenation during arteriovenous malformation resection. Arikan F, Vilalta J, Noguer M, Olive M, Vidal-Jorge M, J. J Neurosurg Sahuquillo Anesthesiol. 2014 Oct; 26 (4): 328-41. DOI: 10.1097 / ANA. 0000000000000033. PMID: 24492516 • [Intraoperative monitoring of oxygen tissue pressure: Applications in vascular neurosurgery]. Arikan F, Vilalta J, Torne R, Chocron I, Rodriguez-Tesouro A, Sahuquillo J. Neurosurgery (Astur). 2014 Nov-Dec; 25 (6): 275-85. DOI: 10.1016 / j.neucir.2014.03.003. Epub 2014 June 14. Spanish. PMID: 24934513 • Rapid resolution of brain ischemic hypoxia after cerebral revascularization in moyamoya disease. Arikan F, Vilalta J, Torne R, Noguer M, Lorenzo-Bosquet C, Sahuquillo J. Neurosurgery. In press. Accepted on October 27, 2014. DOI: 10.1227 / NEU.0000000000000609 PMID: 25584958. Estos estudios proporcionan la siguiente información clínicamente relevante: 1. La monitorización de la PtiO2 permite detectar de una forma rápida y fiable las situaciones de hipoxia cerebral isquémica intraoperatoria, permitiendo establecer estrategias terapéuticas para la resolución de la misma. La monitorización intraoperatoria continua de la PtiO2 es una herramienta útil para reducir las complicaciones isquémicas. 2. La relación PtiO2/PaO2 es un índice superior a los valores absolutos de PtiO2 porque permiten el diagnóstico de la hipoxia tisular cuando los valores de PtiO2 son artificialmente altos debido al aumento de la PaO2 (por ejemplo, en pacientes con ventilación mecánica). El umbral de referencia indicativo de hipoxia tisular para la relación PtiO2/PaO2 es de 0,10 y el umbral indicativo de hiperoxia tisular de 0,35. 3. La relación PtiO2/PaO2 obtenida en sujetos sanos nos demuestra que el oxígeno en el cerebro está fuertemente regulado y que la relación entre la PaO2 y la PtiO2 en el cerebro normal acaba alcanzando una meseta. 4. Confirmamos los hallazgos de otros autores en que muchos pacientes con una malformación arteriovenosa (MAV) presentan una hipoxia cerebral clínicamente bien tolerada en el cerebro de alrededor del nidus malformativo. Nuestros estudios también demuestran que las MAVs pueden provocar cambios en la oxigenación y el metabolismo en zonas cerebrales alejadas del hemisferio ipsilateral. 5. Gran parte de los pacientes con una MAV presentan un patrón hipóxico alrededor del nidus malformativo y/o del cerebro distante. Estos patrones hipóxicos revierten tras la resección de la MAV. 6. La monitorización intraoperatoria de la PtiO2 es un método fiable y seguro para evaluar el estado de la oxigenación y permeabilidad del bypass en pacientes sometidos a cirugía de revascularización cerebral. La hipoxia tisular es casi constante en pacientes tributarios de cirugía de revascularización con enfermedad de Moyamoya y reducción de la reserva de perfusión cerebral. 7. La revascularización directa mediante la realización de un bypass entre la arteria temporal superficial y la arteria cerebral media produce un aumento rápido y sostenido de la PtiO2 que revierten a valores de normoxia.This doctoral thesis consists of four articles that provide new and relevant information about cerebrovascular diseases obtained from intraoperative monitoring of tissue oxygen pressure (PtiO2) using Clark-type polarographic probes. The studies that comprise this thesis are listed below. • [Detection of episodes of ischemic tissue hypoxia by means of the combined intraoperative neurophysiologic monitoring with the tissue oxygenation monitoring in aneurysm surgery]. Arikan F, Vilalta J, Minoves T, Moncho D, Vilalta A, Noguer M, Ibarra B, Sahuquillo J. Neurosurgery (Astur). 2008 Apr; 19 (2): 113-20. Spanish. ISSN: 1130-1473PMID: 18500409. • Intraoperative monitoring of brain tissue oxygenation during arteriovenous malformation resection. Arikan F, Vilalta J, Noguer M, Olive M, Vidal-Jorge M, J. J Neurosurg Sahuquillo Anesthesiol. 2014 Oct; 26 (4): 328-41. DOI: 10.1097 / ANA. 0000000000000033. PMID: 24492516 • [Intraoperative monitoring of oxygen tissue pressure: Applications in vascular neurosurgery]. Arikan F, Vilalta J, Torne R, Chocron I, Rodriguez-Tesouro A, Sahuquillo J. Neurosurgery (Astur). 2014 Nov-Dec; 25 (6): 275-85. DOI: 10.1016 / j.neucir.2014.03.003. Epub 2014 June 14. Spanish. PMID: 24934513 • Rapid resolution of brain ischemic hypoxia after cerebral revascularization in moyamoya disease. Arikan F, Vilalta J, Torne R, Noguer M, Lorenzo-Bosquet C, Sahuquillo J. Neurosurgery. In press. Accepted on October 27, 2014. DOI: 10.1227 / NEU.0000000000000609 PMID: 25584958. These studies provide the clinically relevant information outlined below. 1. Monitoring PtiO2 allows for immediate and reliable detection of ischemic cerebral hypoxia caused by surgical technique and may be used to develop strategies to manage this condition. 2. Continuous monitoring of PtiO2 can be used to quickly and reliably detect situations of intraoperative cerebral ischemic hypoxia and establish therapeutic strategies to resolve it. Continuous intraoperative monitoring of PtiO2 is a useful tool for reducing ischemic complications. 3. The PtiO2/PaO2 ratio is a better index than absolute PtiO2 because it detects hypoxia when absolute values are artifactually high due to increased PaO2 (e.g. patients under mechanical ventilation). The lower reference threshold indicative of tissue hypoxia for the PtiO2/PaO2 ratio is 0.10. The upper reference threshold indicative of tissue hyperoxia for PtiO2/PaO2 is 0.35. 4. PtiO2 / PaO2 ratios obtained in healthy subjects show that oxygen in the brain is heavily regulated and that the relationship between PaO2 and PtiO2 in the normal brain reaches a plateau. 5. The findings of other authors are confirmed by the finding that many patients with AVM present clinically well-tolerated hypoxia in the brain around the nidus. AVMs can cause changes in oxygenation and metabolism in remote areas of the ipsilateral cerebral hemisphere. 6. Many patients with AVM have a hypoxic pattern around the malformation nidus and/or the distant brain. These hypoxic patterns reverse after resection of the AVM. 7. Intraoperative monitoring of PtiO2 is a safe and reliable method to determine brain oxygenation status and patency of bypass in patients undergoing surgery for cerebral revascularization. Tissue hypoxia is almost constant in patients with moyamoya disease and those with a reduction of cerebral perfusion reserve. 8. Direct superficial temporal artery to middle cerebral artery bypass revascularization produces a rapid and sustained increase in PtiO2 and achieves values consistent with normoxia

Elasto-plastic stress analysis in a ductile adhesive & aluminum adherends

© 2016 by the authors; licensee MDPI, Basel, Switzerland.In this study, an elasto-plastic stress analysis is proposed in an aluminum adherend and a ductile adhesive. Elasto-plastic analysis was carried out for the aluminum adherend and DP460 ductile adhesive in a double-lap joint. The analytical solution was compared with the finite element solution. ANSYS 12 was used in the stress analysis. The analytical solution was performed for the one-dimensional case in the adhesive and the adherends. A FEM solution was given for the two-dimensional case. Similar results were obtained for both. In addition, the solution was carried out for brittle and ductile materials. The mechanical properties of the loctite were nearly the same as the ductile DP460 adhesive. It was observed that the ductile adhesive increased the strength of the structure due to the small shear stresses at the free ends of the adhesive