Dauerbruch- und Korrosionsuntersuchungen an oberflächenvergüteten Nickel-Titan- und Titan-Molybdän-Drähten

Das Ziel dieser Arbeit war, die Dauerbruch- und Korrosionsuntersuchungen an oberflächenvergüteten Nickel-Titan- und Titan-Molybdän-Drähten zu testen, um ihre Eigenschaften mit bis auf die Modifikation identischen Proben zu vergleichen. Es wurden hierfür etablierte Messverfahren zum Dauerbruch und zur Korrosion angewendet. Im Anschluss diente bei den Korrosionsuntersuchungen das Atomabsorptionsspektrometer dazu, durch Analyse des Kunstspeichels numerische Resultate zu liefern. Ein Rasterelektronenmikroskop diente der visuellen Analyse beider Versuchsansätze, um die Proben vor und nach dem jeweiligen Versuch auf erkennbare Unterschiede zu überprüfen. Die Drahtbögen wurden von der Firma ODS (Kisdorf, Deutschland) zur Verfügung gestellt. Die Nickel-Titan-Drähte waren Ni-Ti Opto Therm LF .016.022 upper Low Friction sowie Ni-Ti LoFrix Opto TH .016.022 upper der Firma ODS (Kisdorf, Deutschland). Die Titan-Molybdän-Drähte waren zum einen Beta-Titan .016.022 upper LoFrix und zum anderen Beta-Titan .016.022 upper. Die Kennung LoFrix bezieht sich hierbei jeweils auf ein elektrochemisches Vergütungsverfahren der Oberfläche. Für den Dauerlastversuch wurden alle untersuchten Drähte in exakt 2 cm lange Segmente geschnitten. Nach dem Bruchereigniss wurden die Proben einzeln luftdicht aufbewahrt und danach raterelektronenmikroskopisch untersucht. Für den statischen Korrosionstest wurden die Proben in vier mal 1 cm und einmal 1,05 cm lange Abschnitte geschnitten und nach exakt einer Woche in mit Fusayama-Kunstspeichel gefüllten Gefäßen gereinigt und ebenfalls luftdicht gelagert. Daraufhin erfolgte auch hier eine rasterelektronenmikroskopische Untersuchung der Drahtsegmente. Der Kunstspeichel wurde in einem Atomabsorptionsspektrometer auf seine Nickelionenkonzentration untersucht. Die durch die in den in-vitro-Versuchen erzielten Resultate zeigen deutlich die auch klinisch anwendbaren Vorteile der oberflächenmodifizierten Drähte gegenüber den handelsüblichen Chargen. So erwiesen sich die oberflächenvergüteten Drahtproben beider Legierungen in den Dauerlastversuchen als bruchfester. Die Untersuchung der Kunstspeichelproben zeigte bei den oberflächenvergüteten Drahtproben einen niedrigeren Nickelanteil von 1,7 μg/l als bei den nicht oberflächenvergüteten (3,8 μg/l). Die Differenz von 2,1 μg/l ist in Anbetracht der Tatsache, dass es sich um eine Minimierung des Nickelanteils der vergüteten Proben von mehr 100 Prozent handelt, als Erfolg zu werten. Die rasterelektronenmikroskopischen Untersuchungen zeigten bei den Drahtproben nach Oberflächenvergütung eine visuell deutlich erkennbare glattere Oberfläche. Dies ist sowohl in Bezug auf die, mit den Korrosionseigenschaften korrelierende Biokompabilität, als auch auf verbesserte Dauerbrucheigenschaften korrelierenden Behandlungsvorteile ein Fortschritt. Wertet man die positiven Ergebnisse dieser Arbeit mit den ebenfalls positiv zu wertenden Ergebnissen aus der Arbeit von Meier (2014), so erscheint die elektrochemische Behandlung der Drahtproben als erfolgreich

Simultaneous Bedside Assessment of Global Cerebral Blood Flow and Effective Cerebral Perfusion Pressure in Patients with Intracranial Hypertension

Background: We examined a bedside technique transcerebral double-indicator dilution (TCID) for global cerebral blood flow (CBF) as well as the concept of effective cerebral perfusion pressure (CPPeff) during different treatment options for intracranial hypertension, and compared global CBF and CPPeff with simultaneously obtained conventional parameters. Methods: Twenty-six patients developing intracranial hypertension in the course of traumatic brain injury or subarachnoid hemorrhage were prospectively analyzed using a combined assessment during elevated ventilation (n=15) or osmotherapy (hypertonic saline or mannitol). For calculation of global CBF, injections of ice-cold indocyanine green boluses were performed and temperature and dye concentration changes were monitored in the thoracic aorta and the jugular bulb. CBF was then calculated according to the mean transit time principle. Estimation of CCP, the arterial pressure at which cerebral blood flow becomes zero, was performed by synchronized registration of corresponding values of blood flow velocity in the middle cerebral artery and arterial pressure and extrapolation to zero-flow velocity. CPPeff was calculated as mean arterial pressure minus critical closing pressure (CPPeff=MAPc−CCP). Results: Elevated ventilation causes a decrease in both ICP (P<0.001) and CBF (P<0.001). While CPPconv increased (P<0.001), CPPeff decreased during this observation (P=0.002). Administration of osmotherapeutic agents resulted in a decrease of ICP (P<0.001) and a temporary increase of CBF (P=0.052). CPPconv and CPPeff showed no striking difference under osmotherapy. Conclusion: TCID allows repeated measurements of global CBF at the bedside. Elevated ventilation lowered and osmotherapy temporarily raised global CBF. In situations of increased vasotonus, CPPeff is a better indicator of blood flow changes than conventional CP

Nicotine Replacement Therapy for Smokers with Acute Aneurysmal Subarachnoid Hemorrhage: An International Survey

INTRODUCTION Smoking prevalence is twice as high among patients admitted to hospital because of the acute condition of aneurysmal subarachnoid hemorrhage (aSAH) as in the general population. Smoking cessation may improve the prognosis of aSAH, but nicotine replacement therapy (NRT) administered at the time of aSAH remains controversial because of potential adverse effects such as cerebral vasospasm. We investigated the international practice of NRT use for aSAH among neurosurgeons. METHODS The online SurveyMonkey software was used to administer a 15-question, 5-min online questionnaire. An invitation link was sent to those 1425 of 1988 members of the European Association of Neurosurgical Societies (EANS) who agreed to participate in surveys to assess treatment strategies for withdrawal of tobacco smoking during aSAH. Factors contributing to physicians' posture towards NRT were assessed. RESULTS A total of 158 physicians from 50 nations participated in the survey (response rate 11.1%); 68.4% (108) were affiliated with university hospitals and 67.7% (107) practiced at high-volume neurovascular centers with at least 30 treated aSAH cases per year. Overall, 55.7% (88) of physicians offered NRT to smokers with aSAH, 22.1% (35) offered non-NRT support including non-nicotine medication and counselling, while the remaining 22.1% (35) did not actively support smoking cessation. When smoking was not possible, 42.4% (67) of physicians expected better clinical outcomes when prescribing NRT instead of nicotine deprivation, 36.1% (57) were uncertain, 13.9% (22) assumed unaffected outcomes, and 7.6% (12) assumed worse outcomes. Only 22.8% (36) physicians had access to a local smoking cessation team in their practice, of whom half expected better outcomes with NRT as compared to deprivation. CONCLUSIONS A small majority of the surveyed physicians of the EANS offered NRT to support smoking cessation in hospitalized patients with aSAH. However, less than half believed that NRT could positively impact clinical outcome as compared to deprivation. This survey demonstrated the lack of consensus regarding use of NRT for hospitalized smokers with aSAH

Nicotine Replacement Therapy for Smokers with Acute Aneurysmal Subarachnoid Hemorrhage: An International Survey.

Smoking prevalence is twice as high among patients admitted to hospital because of the acute condition of aneurysmal subarachnoid hemorrhage (aSAH) as in the general population. Smoking cessation may improve the prognosis of aSAH, but nicotine replacement therapy (NRT) administered at the time of aSAH remains controversial because of potential adverse effects such as cerebral vasospasm. We investigated the international practice of NRT use for aSAH among neurosurgeons. The online SurveyMonkey software was used to administer a 15-question, 5-min online questionnaire. An invitation link was sent to those 1425 of 1988 members of the European Association of Neurosurgical Societies (EANS) who agreed to participate in surveys to assess treatment strategies for withdrawal of tobacco smoking during aSAH. Factors contributing to physicians' posture towards NRT were assessed. A total of 158 physicians from 50 nations participated in the survey (response rate 11.1%); 68.4% (108) were affiliated with university hospitals and 67.7% (107) practiced at high-volume neurovascular centers with at least 30 treated aSAH cases per year. Overall, 55.7% (88) of physicians offered NRT to smokers with aSAH, 22.1% (35) offered non-NRT support including non-nicotine medication and counselling, while the remaining 22.1% (35) did not actively support smoking cessation. When smoking was not possible, 42.4% (67) of physicians expected better clinical outcomes when prescribing NRT instead of nicotine deprivation, 36.1% (57) were uncertain, 13.9% (22) assumed unaffected outcomes, and 7.6% (12) assumed worse outcomes. Only 22.8% (36) physicians had access to a local smoking cessation team in their practice, of whom half expected better outcomes with NRT as compared to deprivation. A small majority of the surveyed physicians of the EANS offered NRT to support smoking cessation in hospitalized patients with aSAH. However, less than half believed that NRT could positively impact clinical outcome as compared to deprivation. This survey demonstrated the lack of consensus regarding use of NRT for hospitalized smokers with aSAH

Surgery for brain metastases: radiooncology scores predict survival-score index for radiosurgery, graded prognostic assessment, recursive partitioning analysis

BACKGROUND: Radiooncological scores are used to stratify patients for radiation therapy. We assessed their ability to predict overall survival (OS) in patients undergoing surgery for metastatic brain disease. METHODS: We performed a post-hoc single-center analysis of 175 patients, prospectively enrolled in the MetastaSys study data. Score index of radiosurgery (SIR), graded prognostic assessment (GPA), and recursive partitioning analysis (RPA) were assessed. All scores consider age, systemic disease, and performance status prior to surgery. Furthermore, GPA and SIR include the number of intracranial lesions while SIR additionally requires metastatic lesion volume. Predictive values for case fatality at 1 year after surgery were compared among scoring systems. RESULTS: All scores produced accurate reflections on OS after surgery (p ≤ 0.003). Median survival was 21–24 weeks in patients scored in the unfavorable cohorts, respectively. In cohorts with favorable scores, median survival ranged from 42 to 60 weeks. Favorable SIR was associated with a hazard ratio (HR) of 0.44 [0.29, 0.66] for death within 1 year. For GPA, the HR amounted to 0.44 [0.25, 0.75], while RPA had a HR of 0.30 [0.14, 0.63]. Overall test performance was highest for the SIR. CONCLUSIONS: All scores proved useful in predicting OS. Considering our data, we recommend using the SIR for preoperative prognostic evaluation and counseling

Intraoperative angiography reloaded: a new hybrid operating theater for combined endovascular and surgical treatment of cerebral arteriovenous malformations: a pilot study on 25 patients

Background: Multimodality treatment suites for patients with cerebral arteriovenous malformations (AVM) have recently become available. This study was designed to evaluate feasibility, safety and impact on treatment of a new intraoperative flat-panel (FP) based integrated surgical and imaging suite for combined endovascular and surgical treatment of cerebral AVM. Methods: Twenty-five patients with AVMs to treat with combined endovascular and surgical interventions were prospectively enrolled in this consecutive case series. The hybrid suite allows combined endovascular and surgical approaches with intraoperative scanner-like imaging (XperCT®) and intraoperative 3D rotational angiography (3D-RA). The impact of intraoperative multimodal imaging on feasibility, workflow of combined interventions, surgery, and unexpected imaging findings were analyzed. Results: Twenty-five patients (mean age 38 ± 18.6year) with a median Spetzler-Martin grade 2 AVM (range 1-4) underwent combined endovascular and surgical procedures. Sixteen patients presented with a ruptured AVM and nine with an unruptured AVM. In 16% (n = 4) of cases, intraoperative imaging visualized AVM remnants ≤3mm and allowed for completion of the resections in the same sessions. Complete resection was confirmed in all n = 16 patients who had follow-up angiography oneyear after surgery so far. All diagnostic and therapeutical steps, including angiographic control, were performed without having to move the patients Conclusion: The hybrid neurointerventional suite was shown to be a safe and useful setup which allowed for unconstrained combined microsurgical and neuroradiological workflow. It reduces the need for extraoperative angiographic controls and subsequent potential surgical revisions a second time, as small AVM remnants can be detected with high securit

Introducing a nationwide registry: the Swiss study on aneurysmal subarachnoid haemorrhage (Swiss SOS)

Background: Aneurysmal subarachnoid haemorrhage (aSAH) is a haemorrhagic form of stroke and occurs in a younger population compared with ischaemic stroke or intracerebral haemorrhage. It accounts for a large proportion of productive life-years lost to stroke. Its surgical and medical treatment represents a multidisciplinary effort. Due to the complexity of the disease, the management remains difficult to standardise and quality of care is accordingly difficult to assess. Objective: To create a registry to assess management parameters of patients treated for aSAH in Switzerland. Methods: A cohort study was initiated with the aim to record characteristics of patients admitted with aSAH, starting January 1st 2009. Ethical committee approval was obtained or is pending from the institutional review boards of all centres. In the study period, seven Swiss hospitals (five university [U], two non-university medical centres) harbouring a neurosurgery department, an intensive care unit and an interventional neuroradiology team so far agreed to participate in the registry (Aarau, Basel [U], Bern [U], Geneva [U], Lausanne [U], St. Gallen, Zürich [U]). Demographic and clinical parameters are entered into a common database. Discussion: This database will soon provide (1) a nationwide assessment of the current standard of care and (2) the outcomes for patients suffering from aSAH in Switzerland. Based on data from this registry, we can conduct cohort comparisons or design diagnostic or therapeutic studies on a national level. Moreover, a standardised registration system will allow healthcare providers to assess the quality of car