Study of flow-induced hemolysis using novel Couette-type blood-shearing devices

To assist the development and application of blood-contacting medical devices, two novel flow-through Couette-type blood-shearing devices have been developed to study the quantitative relationship between blood damage indexes and flow-dependent parameters. One device is an axial flow-through Couette-type device supported by a pair of pin bearings adapted from the adult Jarvik 2000 blood pump. The other is a centrifugal flow-through Couette-type device supported with magnetic bearings adapted from the CentriMag blood pump. In both devices, a rotor spindle was used to replace the original impeller blades so that a small gap was created between the housing and the rotating spindle surface. Computational fluid dynamics simulations have shown that a uniform, high shear stress region can be generated inside the small gap while the shear stresses elsewhere are relatively low. The possibility of secondary blood damage caused by mechanical seals was eliminated due to the use of a magnetic rotor system. Blood flow through the gap was driven by an externally pressurized reservoir. By adjusting the rotational speed and blood flow rate, shear-induced hemolysis was quantified at a matrix of exposure time (0.039 to 1.48 s) and shear stress (50 to 320 Pa). All of the experiments were conducted at room temperature using heparinized ovine blood with a hematocrit value of 30%. The measured hemolysis levels were much lower than those published in the literature, and the overestimation of those earlier studies may be attributable to device-related secondary blood-damaging effects. A new set of coefficients for the power law model was derived from the regression of the experimental data.     

Technology assessment in radiology: putting the evidence in evidence-based radiology

In this review, which is part of a larger series on evidence-based practice in radiology, the relationship between technology assessment (TA) and the practice of evidence-based radiology (EBR) is discussed. TA guides researchers in the methods required to be reliable providers of unbiased and relevant evidence. Meanwhile, EBR equips radiologists with the skills needed to be discerning consumers of that evidence. Both paradigms aim to improve the effectiveness of health care spending. In this review, it is argued that EBR can be only as good as the TA on which it is based. However, TA is particularly complex in regard to diagnostic radiology because of the many links in the chain between the interim objective (to make the correct diagnosis) and the ultimate goal (to improve patient health). In this article, the development of TA in medicine in general and, more specifically, the TA hierarchy for the evaluation of diagnostic imaging are described. Some of the improvements in the pool of evidence during the past 30 years are documented, and some of the remaining tensions between TA and EBR are highlighted.     

Evidence-Based Imaging and Effective Utilization: Lessons in Neuroradiology

Expensive advanced imaging, such as magnetic resonance (MR) imaging, contributes to the unsustainable growth of health care costs in the United States. Evidence-based imaging decreases costs and improves outcomes by guiding appropriate utilization of imaging. Low back pain is an important case illustration. Despite strong evidence that early advanced imaging with MR imaging for uncomplicated low back pain leads to increased costs without significant clinical benefit, MR imaging utilization for acute low back pain has increased. Barriers to evidence-based imaging can be traced to patient- and physician-related factors. Radiologists have a critical role in addressing some of these barriers.     

Comment on "Multidimensional results reporting to participants in genomic studies: getting it right"

Bookman et al. write to correct the impression given in the Commentary by Kohane and Taylor that the recommendations of the National Heart, Lung, and Blood Institute (NHLBI) Working Group "Reporting Genetic Results in Research Studies" included advice to return genetic information to research subjects only in cases where there is a proven or preventative intervention for the identified disorder. In fact, the report does recommend that genetic information be returned to subjects when there is an intervention available, but it does not recommend against giving this kind of information to subjects if there is no available intervention.     

Developing best practice for fungal specimen management: audit of UK microbiology laboratories

This study represents an audit of microbiology laboratories in the UK to ascertain whether they are aware of, or follow, the Health Protection Agency (HPA) National Standard Methods Standard Operating Procedure (NSM SOP) for the investigation of dermatological specimens for superficial mycoses, or use a locally adapted version. A questionnaire audit was distributed to 179 NHS microbiology laboratories throughout England, Wales, Scotland and Northern Ireland. The NSM SOP was followed by 92% of laboratories for the microscopy of dermatological samples; light microscopy/ KOH digestion was used by 63% and fluorescence microscopy/KOH digestion by 29% of laboratories. Preliminary reports post-microscopy were issued by 98% of laboratories, with 93% issuing reports within 48 hours. Adherence to the NSM SOP guidelines for culture was low; only 34% of laboratories incubated microscopy-negative specimens for the recommended 14 days, while approximately 60% incubated microscopy-positive specimens for 21 days. The culture medium recommended by the NSM SOP was used in 82% of laboratories. Comments were added to culture reports by 51% of laboratories; most were added manually and comments varied between laboratories. Nail samples were the most common sample received from primary care, followed by skin and hair. These results show no significant difference in the rate of microscopy positives versus culture positives. Microscopy and culture are the easiest and cheapest methods available to UK laboratories for the investigation of suspected superficial fungal infections. Although most laboratories included in this audit claimed to follow the NSM SOP for microscopy and culture, these results show that the techniques used vary throughout the UK. To maximise the service provided to primary care, UK laboratories should use standardise methods based on the NSM SOP.