Showing papers by "Alan H. Morris published in 2012"

Automatic classification of scar tissue in late gadolinium enhancement cardiac MRI for the assessment of left-atrial wall injury after radiofrequency ablation

Abstract: Radiofrequency ablation is a promising procedure for treating atrial fibrillation (AF) that relies on accurate lesion delivery in the left atrial (LA) wall for success. Late Gadolinium Enhancement MRI (LGE MRI) at three months post-ablation has proven effective for noninvasive assessment of the location and extent of scar formation, which are important factors for predicting patient outcome and planning of redo ablation procedures. We have developed an algorithm for automatic classification in LGE MRI of scar tissue in the LA wall and have evaluated accuracy and consistency compared to manual scar classifications by expert observers. Our approach clusters voxels based on normalized intensity and was chosen through a systematic comparison of the performance of multivariate clustering on many combinations of image texture. Algorithm performance was determined by overlap with ground truth, using multiple overlap measures, and the accuracy of the estimation of the total amount of scar in the LA. Ground truth was determined using the STAPLE algorithm, which produces a probabilistic estimate of the true scar classification from multiple expert manual segmentations. Evaluation of the ground truth data set was based on both inter- and intra-observer agreement, with variation among expert classifiers indicating the difficulty of scar classification for a given a dataset. Our proposed automatic scar classification algorithm performs well for both scar localization and estimation of scar volume: for ground truth datasets considered easy, variability from the ground truth was low; for those considered difficult, variability from ground truth was on par with the variability across experts.

The evolution of eProtocols that enable reproducible clinical research and care methods

Abstract: Unnecessary variation in clinical care and clinical research reduces our ability to determine what healthcare interventions are effective. Reducing this unnecessary variation could lead to further healthcare quality improvement and more effective clinical research. We have developed and used electronic decision support tools (eProtocols) to reduce unnecessary variation. Our eProtocols have progressed from a locally developed mainframe computer application in one clinical site (LDS Hospital) to web-based applications available in multiple languages and used internationally. We use eProtocol-insulin as an example to illustrate this evolution. We initially developed eProtocol-insulin as a local quality improvement effort to manage stress hyperglycemia in the adult intensive care unit (ICU). We extended eProtocol-insulin use to translate our quality improvement results into usual clinical care at Intermountain Healthcare ICUs. We exported eProtocol-insulin to support research in other US and international institutions, and extended our work to the pediatric ICU. We iteratively refined eProtocol-insulin throughout these transitions, and incorporated new knowledge about managing stress hyperglycemia in the ICU. Based on our experience in the development and clinical use of eProtocols, we outline remaining challenges to eProtocol development, widespread distribution and use, and suggest a process for eProtocol development. Technical and regulatory issues, as well as standardization of protocol development, validation and maintenance, need to be addressed. Resolution of these issues should facilitate general use of eProtocols to improve patient care.

Exciting new ECMO technology awaits compelling scientific evidence for widespread use in adults with respiratory failure

Abstract: MacLaren et al. [1] discuss the exciting potential offeredby extracorporeal support, including extracorporealmembrane oxygenation (ECMO). Many uses of ECMOhave recently been discussed. These include a technicallyadvanced means of transporting patients with severerespiratory failure [2] and a treatment for acute respira-tory distress syndrome (ARDS) following novel H1N1influenza infection [3]. Extracorporeal support remains anexciting domain of investigation, development and clini-cal application. Innovations, such as IVOX, aboundamong developers and practitioners of extracorporealsupport [4]. Dr. Bartlett has been a consistent leader andinnovator in this field.MacLaren et al. [1] make impressive arguments, andtheir illustrations are clear and compelling. Their Fig. 6 isa striking example of the advances/changes in clinicalcare. The new extracorporeal circuits they nicely describeare clearly much simpler, easier to use, and appear moresafe than those used in the past. Importantly, they appearsafer than those used in the two past clinical trials thatadhered to accepted experimental standards [5, 6]. Thisraises legitimate questions about the current value of theresults of those two older clinical trials. These legitimatequestions should be answered with new clinical trials thatadhere to accepted experimental standards. The authorsclearly indicate that major advances in both extracorpo-real circuitry and clinical care have taken place, since thetechnology of these two older clinical trials was intro-matched by similar advances in extracorporeal clinicaltrials. Rigorous clinical trials with modern technologywill likely provide results that answer crucial questionsabout ‘‘in whom, how, and when’’ extracorporeal supportshould be applied.The experimental design of two-group randomizedcontrolled clinical trials has not changed substantiallysince the older trials were completed [5, 6]. In the absenceof credible new clinical trial results, we have no betterinformation to guide decisions about widespread use ofextracorporeal support than that provided by the two pastclinical trials that adhered to accepted experimentalstandards [5, 6]. Some clinicians hold strong beliefs in theefficacy of ECMO support for patients with severe ARDS.Dr. MacLaren [7] articulately expressed these beliefs in arecent letter. Such strong beliefs are not new. In 1984 and1985 Gattinoni et al. [8] reported a dramatic increase insurvival with use of low frequency positive pressureventilation with extracorporeal carbon dioxide removal(LFPPV-ECCO2R) (using veno-venous support). Mycolleagues and I conducted a randomized controlledclinical trial with the expectation that LFPPV-ECCO2Rwas likely to be a significant treatment advance (from ourpublished discussion: ‘‘...we concluded from publishedreports that there was about a 0.5 prior probability thatLFPPV-ECCO2R was a superior therapy for ARDS’’ [6]).However, we did not detect a survival advantage ofLFPPV_ECCO2R. Gattinoni et al., in a letter to the edi-tor, replied that the LFPPV_ECCO2R technique was notyet optimized and the technique not yet ready for aclinical trial (see letters to the editor in [6]). We asked, ina reply letter, how it could be known that the LFPPV-ECCO2R technique was beneficial (the conclusion of thestrong believers) when the technique was not yet

Outdoor far-field antenna measurements system for testing of large vehicles

Abstract: The Electronic Proving Ground's Antenna Test Facility at Fort Huachuca, Arizona has some of the most interesting testing structures in the world. These structures include a wooden Arc measurements system with a 23 m radius, a 30 m tower, and a compact range with an 18 m quiet zone. All of these structures are outdoors and support testing from UHF to mm frequencies on antenna systems mounted on large land and air vehicles. This paper describes the ranges supported by these structures (some of which were built in the late 1960's) and the efforts made to keep these ranges current. This paper also describes an economical approach to arc range design which moves the arc instead of the vehicles. This paper discusses plans to build one of these systems outdoors at EPG within a limited budget.

Let us be cautious and prevent unnecessary patient harm

Abstract: Foi utilizada uma tecnica de ECMO moderna, e a paciente sobreviveu. Esta claro que a ECMO e uma tecnica de suporte dramatica, e a sobrevivencia de um paciente propenso ao obito pode facilmente levar os clinicos a crer na eficacia da tecnica. Contudo, a cognicao e a crenca humanas sao processos complexos os quais tem limites importantes e frequentemente levam a conclusoes incorretas.

Standardizing self-reported surveys in critical care: a good idea.

Abstract: relate with measures of central cardiovascular function (8, 9). The finding that StO2 varies by location even within the same patient does raise important questions of standardization and generalization of StO2 measurement in the management of shock. Critical aspects of near-infrared spectroscopy measurement include not only the location, but also the measurement probe characteristics and the mathematical algorithm used to calculate the StO2. In the present study, Colin and colleagues used a near-infrared spectroscopy probe with a 25-mm depth. It is not known if other commercially available probes with 15-mm depths will produce the same results. For StO2 measurement to become broadly applied in sepsis management, standardization of equipment and technique must be achieved. A significant potential advantage of tissue StO2 measurement for prognostication and as a therapeutic monitor is that it does not carry the risks, time, and expense of central venous catheter placement. Colin and colleagues have shown that masseter StO2 may rapidly and noninvasively identify sepsis patients with superior vena cava oxygen saturation 70%. These results in combination with previously published results offer the possibility for clinicians to combine both central hemodynamic as well as microcirculatory factors to develop individualized treatment plans. However, before any monitor can be considered truly valuable in the management of shock or sepsis, it must be shown to be consistent over time, characterized in a broad range of patient populations, and responsive to the success or failure of treatment. Interpretation of the test results should be directly related to meaningful, patient-centered outcomes. Finally, because our management of sepsis remains imperfect, the ideal clinical patient monitoring technique should provide additional insight into the pathophysiology of the disease and suggest new avenues for treatment. Masseter muscle StO2 measurement has not yet achieved this status, but it certainly gives us something to chew on. Karl Thomas, MD Kevin Doerschug, MD Division of Pulmonary and Critical Care Medicine University of Iowa Carver College of Medicine Iowa City, IA

Framework Application for Core Edge Transport Simulation (FACETS)

Abstract: The goal of the FACETS project (Framework Application for Core-Edge Transport Simulations) was to provide a multiphysics, parallel framework application (FACETS) that will enable whole-device modeling for the U.S. fusion program, to provide the modeling infrastructure needed for ITER, the next step fusion confinement device. Through use of modern computational methods, including component technology and object oriented design, FACETS is able to switch from one model to another for a given aspect of the physics in a flexible manner. This enables use of simplified models for rapid turnaround or high-fidelity models that can take advantage of the largest supercomputer hardware. FACETS does so in a heterogeneous parallel context, where different parts of the application execute in parallel by utilizing task farming, domain decomposition, and/or pipelining as needed and applicable. ParaTools, Inc. was tasked with supporting the performance analysis and tuning of the FACETS components and framework in order to achieve the parallel scaling goals of the project. The TAU Performance System® was used for instrumentation, measurement, archiving, and profile / tracing analysis. ParaTools, Inc. also assisted in FACETS performance engineering efforts. Through the use of the TAU Performance System, ParaTools provided instrumentation, measurement, analysis and archival support for the FACETSmore » project. Performance optimization of key components has yielded significant performance speedups. TAU was integrated into the FACETS build for both the full coupled application and the UEDGE component. The performance database provided archival storage of the performance regression testing data generated by the project, and helped to track improvements in the software development.« less