Metric based virtual simulation training for endovascular thrombectomy improves interventional neuroradiologists’ simulator performance

Objective Metric based virtual reality simulation training may enhance the capability of interventional neuroradiologists (INR) to perform endovascular thrombectomy. As pilot for a national simulation study we examined the feasibility and utility of simulated endovascular thrombectomy procedures on a virtual reality (VR) simulator. Methods Six INR and four residents participated in the thrombectomy skill training on a VR simulator (Mentice VIST 5G). Two different case-scenarios were defined as benchmark-cases, performed before and after VR simulator training. INR performing endovascular thrombectomy clinically were also asked to fill out a questionnaire analyzing their degree of expectation and general attitude towards VR simulator training. Results All participants improved in mean total procedure time for both benchmark-cases. Experts showed significant improvements in handling errors (case 2), a reduction in contrast volume used (case 1 and 2), and fluoroscopy time (case 1 and 2). Novices showed a significant improvement in steps finished (case 2), a reduction in fluoroscopy time (case 1), and radiation used (case 1). Both, before and after having performed simulation training the participating INR had a positive attitude towards VR simulation training. Conclusion VR simulation training enhances the capability of INR to perform endovascular thrombectomy on the VR simulator. INR have generally a positive attitude towards VR simulation training. Whether the VR simulation training translates to enhanced clinical performance will be evaluated in the ongoing Norwegian national simulation study.publishedVersio

Airway symptoms and atopy in young children prescribed asthma medications:A large-scale cohort study

Diagnosing asthma and deciding treatment are difficult in young children. An inappropriate and too high prescription rate of inhaled corticosteroids (ICS) is suggested, but how airway symptoms are associated with prescriptions of asthma medication is less known. We studied how strongly wheeze, lower respiratory tract infections (LRTI), and atopic diseases are associated with dispensing of asthma medications during early childhood. We used data from the Norwegian Mother and Child Cohort Study and the Norwegian Prescription Database at four age‐intervals (0‐6, 6‐18, 18‐36 months, and 3‐7 years). Primary outcomes were dispensed asthma medications (no medication, short‐acting β‐2 agonist, or ICS). Relative risks (RRs) and average attributable fractions (AAFs) were estimated. Both wheeze and LRTI were positively associated with both medication groups (0‐6 months: no data on wheeze). The RRs and AAFs were higher for wheeze than LRTI. For ICS, the AAFs (95% CI) for wheeze vs LRTI were: 6 to 18 months: 69.2 (67.2, 71.2)% vs 10.4 (9.0, 11.8)%, 18 to 36 months: 33.0 (30.5, 35.5)% vs 10.0 (8.0, 12.0)%, and 3 to 7 years: 33.7 (31.0, 36.5)% vs 1.2 (0.5, 1.9)%. Except at 3 to 7 years of age, the AAFs were lower for atopic diseases than for LRTI and wheeze. Atopic diseases modified the associations between wheeze and ICS at 18 to 36 months and between LRTI or wheeze and ICS at 3 to 7 years. In conclusion, both wheeze and LRTI were associated with prescriptions of asthma medications in young children, with the strongest associations seen for wheeze. Atopic diseases contributed to these associations only in the oldest age groups.publishedVersio

Six-Month Survival After Extracorporeal Membrane Oxygenation for Severe COVID-19

Objectives: The authors evaluated the outcome of adult patients with coronavirus disease 2019 (COVID-19)-related acute respiratory distress syndrome (ARDS) requiring the use of extracorporeal membrane oxygenation (ECMO). Design: Multicenter retrospective, observational study. Setting: Ten tertiary referral university and community hospitals. Participants: Patients with confirmed severe COVID-19-related ARDS. Interventions: Venovenous or venoarterial ECMO. Measurements and Main Results: One hundred thirty-two patients (mean age 51.1 +/- 9.7 years, female 17.4%) were treated with ECMO for confirmed severe COVID-19-related ARDS. Before ECMO, the mean Sequential Organ Failure Assessment score was 10.1 +/- 4.4, mean pH was 7.23 +/- 0.09, and mean PaO2/fraction of inspired oxygen ratio was 77 +/- 50 mmHg. Venovenous ECMO was adopted in 122 patients (92.4%) and venoarterial ECMO in ten patients (7.6%) (mean duration, 14.6 +/- 11.0 days). Sixty-three (47.7%) patients died on ECMO and 70 (53.0%) during the index hospitalization. Six-month all-cause mortality was 53.0%. Advanced age (per year, hazard ratio [HR] 1.026, 95% CI 1.000-1-052) and low arterial pH (per unit, HR 0.006, 95% CI 0.000-0.083) before ECMO were the only baseline variables associated with increased risk of six-month mortality. Conclusions: The present findings suggested that about half of adult patients with severe COVID-19 -related ARDS can be managed successfully with ECMO with sustained results at six months. Decreased arterial pH before ECMO was associated significantly with early mortality. Therefore, the authors hypothesized that initiation of ECMO therapy before severe metabolic derangements subset may improve survival rates significantly in these patients. These results should be viewed in the light of a strict patient selection policy and may not be replicated in patients with advanced age or multiple comorbidities. (C) 2021 The Authors. Published by Elsevier Inc.Peer reviewe

Exploring Reinforcement Learning for End-Diastolic and End-Systolic Frame Detection

The thesis explores ways of formulating the problem of detecting the key cardiac phases from ultrasound videos, i.e., the end diastolic (ED) and end systolic (ES) phases, as a reinforcement learning (RL) problem, and whether there are any benefits in doing so. Of particular interest is the design of the RL reward function. Three reward functions are explored: one based on a generalization of the performance metric of average absolute frame difference (aaFD) that is only given to the agent at the end of an episode, and two based on per-frame phase classification given at every step. Additionally, two formulations of the RL environment are explored: binary classification environment (BCE), designed to be a direct reformulation of a supervised binary classification task, and m-mode binary classification environment (MMBCE), designed to provide the agent with the ability to explore the environment using synthetic m-mode imaging. Because of time constraints, MMBCE was only preliminary explored, yet the results indicate that the problem is too complex for the current setup and requires more work before we can draw any conclusions on its feasibility. Experiments show that an RL agent is able to learn to perform phase detection even when the reward signal is very sparse. However, the less sparse reward functions perform better on nearly all metrics. The best agent predicts the correct number of ED and ES events in $\sim 80\%$ of the videos on the test set, on which it yields an aaFD score of 1.69. It is concluded that there are multiple ways of formulating the problem of phase detection as a reinforcement learning problem, but not all formulations perform equally well. Reward sparsity and environment complexity contribute negatively to performance overall. There are also indications that lower values of the epsilon-greedy exploration hyperparameter epsilon have a regularizing effect on the model, prompting further research

Aerodynamic Stability of Long-span Suspension Bridges

A MATLAB script for making customized finite element models of suspension bridges is created. The main purpose of the script is to perform eigenvalue analysis of different bridge setups to investigate the controlling parameters for the torsional-to-vertical frequency ratios. The modal output from the model is used to perform aerodynamic stability analysis. The in-wind complex eigenvalue problem (CEV) is solved in an iterative procedure in order to locate the stability limits of the various bridge setups. The bridge geometries investigated originates from a conceptual study on triple-girder flutter-free bridges conducted by Michael Styrk Andersen at The University of Southern Denmark. The FE-model is verified by analysing the Hardanger Bridge. Both the model output and the instability limit, found as 77.5 m/s, is in good agreement with previous research. The results for other setups gave reasonable natural frequencies and mode shapes, and are verified by simplified calculations made by Michael Styrk Andersen. The widest triple-girder configuration, Setup 3, shows below unity frequency ratios, as expected. The importance of pylon stiffness is investigated, and it is concluded that the natural frequencies are not very sensitive to changes in pylon stiffness. An analysis is made to determine what effect the crossbeam stiffness has on the natural frequencies. For very stiff crossbeams the frequency ratio of Setup 3 was inverted. This allows classical flutter, reducing the stability limit considerably. The available literature has been searched for applicable aerodynamic derivatives for the configurations that are studied. The Messina ADs are implemented for the triple-girder setups. The results are not satisfactory as they are highly unstable regarding the choice of curve fitting. Therefore all setups are analysed using Hardanger and Theodorsen ADs. Michael has planned and performed wind tunnel tests on Setup 1-3 parallel with the work on this project. The data is not yet processed as this report is in its finishing stages. It is therefore left for further work to analyse the stability of these setups with the correct ADs. Besides the verification by Hardanger Bridge, there are mainly three different bridge setups analysed. They are all fictitious designs of a suspension bridge crossing Halsafjorden on the Norwegian coastal highway E39. The bridges has main spans of 2050 meters. Setup 1 is a single hollow-box girder similar to the Hardanger bridge girder. The stability limit is 26.5 m/s, and denotes the wind velocity at which the bridge deck enters coupled flutter in the first pair of symmetric modes. Setup 2 has a medium wide triple-girder bridge deck. With Hardanger ADs it undergoes classical flutter at 28.2 m/s, in good correspondence with observed behaviour in wind tunnel testing. The stability limit of Setup 3 is not identified by the complex eigenvalue procedure applied because of the low frequency ratios. The results indicate a critical wind speed of circa 71 m/s for torsional divergence. Unlike the Hardanger analysis, all setups with span-length 2050 meters has considerable lateral deflections in the anti-symmetric torsional modes. This increases the effect of the lateral ADs on the critical wind speed and frequencies. It is however observed that neglecting these ADs is conservative for all analyses in this report. The in-wind characteristics of suspension bridges with low torsional-to-vertical frequency ratios are investigated. The present results indicates that such bridges has good aerodynamic performance and that flutter instability is avoided. Achieving such low frequency ratios is though compromising for the torsional stiffness of the bridge deck girder, causing fairly low stability limits for static divergence. A CEV analysis of Setup 3 with improved torsional stiffness is conducted, indicating an improvement of the wind velocity at which static divergence occurs. The results indicate a critical wind velocity for static divergence of 91 m/s when increasing the cable distance from 30 to 40 meters. This result verifies indications made in existing research on similar bridges

Sykling i blandet trafikk

Prosjektoppgave i EPT-100 Sikkerhetsstyring i vegtrafikken Våren2011 Universitetet i Stavange

Temporal changes in cardiac troponin i are associated with risk of cardiovascular events in the general population: The Nord-Trøndelag health study

Cardiac troponins are associated with cardiovascular risk in the general population, but whether temporal changes in cardiac troponin I provide independent prognostic information remains uncertain. Using a large community-based cohort with follow-up close to the present day, we aimed to investigate the associations between temporal changes in cardiac troponin and cardiovascular events. We measured cardiac troponin I with a high-sensitivity assay (hs-cTnI) in 4805 participants attending both the second (HUNT 2, 1995–97) and third wave (HUNT 3, 2006–2008) of the prospective observational Nord-Trøndelag Health (HUNT) Study. We constructed statistical models with both relative and absolute changes of hs-cTnI from HUNT 2 to HUNT 3. A composite end point of cardiovascular death or first admission for myocardial infarction or heart failure was generated. Participants with relative decrease in hs-cTnI were more frequently younger and female and had lower blood pressure and body mass index. Participants with relative increase in hs-cTnI more frequently were older and male, with higher systolic blood pressure. The adjusted hazard ratio (HR) for relative increase in hs-cTnI was 1.68 (95% CI, 1.16–2.42) and the adjusted HR for relative decrease was 1.19 (95% CI, 0.84–1.68). Absolute increases in hs-cTnI exhibited similar prognostic properties as relative increases in hs-cTnI. The most recent measurement of hs-cTnI outperformed the change variables in discrimination and reclassification models. Both relative and absolute increases in hs-cTnI are independently associated with cardiovascular risk. For refinement of risk prediction models, the most recent measurement of hs-cTnI should be preferred in clinical practice