Modeling elastic wave propagation in fluid-filled boreholes drilled in nonhomogeneous media: BEM – MLPG versus BEM-FEM coupling

The efficiency of two coupling formulations, the boundary element method (BEM)-meshless local Petrov–Galerkin (MLPG) versus the BEM-finite element method (FEM), used to simulate the elastic wave propagation in fluid-filled boreholes generated by a blast load, is compared. The longitudinal geometry is assumed to be invariant in the axial direction (2.5D formulation). The material properties in the vicinity of the borehole are assumed to be nonhomogeneous as a result of the construction process and the ageing of the material. In both models, the BEM is used to tackle the propagation within the fluid domain inside the borehole and the unbounded homogeneous domain. The MLPG and the FEM are used to simulate the confined, damaged, nonhomogeneous, surrounding borehole, thus utilizing the advantages of these methods in modeling nonhomogeneous bounded media. In both numerical techniques the coupling is accomplished directly at the nodal points located at the common interfaces. Continuity of stresses and displacements is imposed at the solid–solid interface, while continuity of normal stresses and displacements and null shear stress are prescribed at the fluid–solid interface. The performance of each coupled BEM-MLPG and BEM-FEM approach is determined using referenced results provided by an analytical solution developed for a circular multi-layered subdomain. The comparison of the coupled techniques is evaluated for different excitation frequencies, axial wavenumbers and degrees of freedom (nodal points).Ministerio de Economía y Competitividad BIA2013-43085-PCentro Informático Científico de Andalucía (CICA

Wearable cardioverter defibrillators for the prevention of sudden cardiac arrest: a health technology assessment and patient focus group study

Sabine Ettinger,1 Michal Stanak,1 Piotr Szymański,2 Claudia Wild,1 Romana Tandara Haček,3 Darija Erčević,3 Renata Grenković,3 Mirjana Huić3 1Ludwig Boltzmann Institute for Health Technology Assessment, Vienna, Austria; 2Institute of Cardiology, Warsaw, Poland; 3Department for Development, Research and Health Technology Assessment, Agency for Quality and Accreditation in Health Care and Social Welfare, Zagreb, Croatia Aim: To summarize the evidence on clinical effectiveness and safety of wearable cardioverter defibrillator (WCD) therapy for primary and secondary prevention of sudden cardiac arrest in patients at risk. Methods: We performed a systematic literature search in databases including MEDLINE via OVID, Embase, the Cochrane Library, and CRD (DARE, NHS-EED, HTA). The evidence obtained was summarized according to GRADE methodology. A health technology assessment (HTA) was conducted using the HTA Core Model® for rapid relative effectiveness assessment. Primary outcomes for the clinical effectiveness domain were all-cause and disease-specific mortality. Outcomes for the safety domain were adverse events (AEs) and serious adverse events (SAEs). A focus group with cardiac disease patients was conducted to evaluate ethical, organizational, patient, social, and legal aspects of the WCD use. Results: No randomized- or non-randomized controlled trials were identified. Non-comparative studies (n=5) reported AEs including skin rash/itching (6%), false alarms (14%), and palpitations/light-headedness/fainting (9%) and discontinuation due to comfort/lifestyle issues (16–22%), and SAEs including inappropriate shocks (0–2%), unsuccessful shocks (0–0.7%), and death (0–0.3%). The focus group results reported that experiencing a sense of security is crucial to patients and that the WCD is not considered an option for weeks or even months due to expected restrictions in living a “normal” life. Conclusion: The WCD appears to be relatively safe for short-to-medium term, but the quality of existing evidence is very low. AEs and SAEs need to be more appropriately reported in order to further evaluate the safety of the device. High-quality comparative evidence and well-described disease groups are required to assess the effectiveness of the WCD and to determine which patient groups may benefit most from the intervention. Keywords: sudden cardiac arrest, ventricular tachycardia, ventricular fibrillation, cardioverter defibrillator, external, wearable, patient involvemen

Reply to: Comments on the authors’ reply to the critical appraisal concerning “Wearable cardioverter defibrillators for the prevention of sudden cardiac arrest: a health technology assessment and patient focus group study”

Sabine Ettinger,1 Michal Stanak,1 Piotr Szymański,2 Claudia Wild,1 Romana Tandara Haček,3 Darija Erčević,3 Renata Grenković,3 Gregor Goetz,1 Mirjana Huić3 1Ludwig Boltzmann Institute for Health Technology Assessment, Vienna, Austria; 2Institute of Cardiology, Warsaw, Poland; 3Department for Development, Research, and Health Technology Assessment, Agency for Quality and Accreditation in Health Care and Social Welfare, Zagreb, CroatiaAlthough we clearly outlined our answers in our previous letter,1 we are pleased to clarify further any remaining open issues. There might be diverse views with regard to comparators of the wearable cardioverter defibrillator (WCD). We would like to refer the readers to our previous answer,1 where we explained our rationale for choosing the implantable cardioverter defibrillator as one of the comparators. It was selected based on broad indications stated in the CE mark and after discussions with clinicians. Furthermore, in this case, a change of the comparator, ie, the implantable cardioverter defibrillator, would not have led to a different result or conclusion.View the original paper by Ettinger and colleagues.Two previous letters have been published Sperzel et al Sperzel et a

Core competencies for ethics experts in health technology assessment

Objectives. There is no consensus on who might be qualified to conduct ethical analysis in the field of health technology assessment (HTA). Is there a specific expertise or skill set for doing this work? The aim of this article is to (i) clarify the concept of ethics expertise and, based on this, (ii) describe and specify the characteristics of ethics expertise in HTA. Methods. Based on the current literature and experiences in conducting ethical analysis in HTA, a group of members of the Health Technology Assessment International (HTAi) Interest Group on Ethical Issues in HTA critically analyzed the collected information during two face-to-face workshops. On the basis of the analysis, working definitions of \u201cethics expertise\u201d and \u201ccore competencies\u201d of ethics experts in HTA were developed. This paper reports the output of the workshop and subsequent revisions and discussions online among the authors. Results. Expertise in a domain consists of both explicit and tacit knowledge and is acquired by formal training and social learning. There is a ubiquitous ethical expertise shared by most people in society; nevertheless, some people acquire specialist ethical expertise. To become an ethics expert in the field of HTA, one needs to acquire general knowledge about ethical issues as well as specific knowledge of the ethical domain in HTA. The core competencies of ethics experts in HTA consist of three fundamental elements: knowledge, skills, and attitudes. Conclusions. The competencies described here can be used by HTA agencies and others involved in HTA to call attention to and strengthen ethical analysis in HTA