33 research outputs found

    Modelling of impaired cerebral blood flow due to gaseous emboli

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    Bubbles introduced to the arterial circulation during invasive medical procedures can have devastating consequences for brain function but their effects are currently difficult to quantify. Here we present a Monte-Carlo simulation investigating the impact of gas bubbles on cerebral blood flow. For the first time, this model includes realistic adhesion forces, bubble deformation, fluid dynamical considerations, and bubble dissolution. This allows investigation of the effects of buoyancy, solubility, and blood pressure on embolus clearance. Our results illustrate that blockages depend on several factors, including the number and size distribution of incident emboli, dissolution time and blood pressure. We found it essential to model the deformation of bubbles to avoid overestimation of arterial obstruction. Incorporation of buoyancy effects within our model slightly reduced the overall level of obstruction but did not decrease embolus clearance times. We found that higher blood pressures generate lower levels of obstruction and improve embolus clearance. Finally, we demonstrate the effects of gas solubility and discuss potential clinical applications of the model

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    What’s in a Name? Use of Brand versus Generic Drug Names in United States Outpatient Practice

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    BACKGROUND: The use of brand rather than generic names for medications can increase health care costs. However, little is known at a national level about how often physicians refer to drugs using their brand or generic names. OBJECTIVE: To evaluate how often physicians refer to drugs using brand or generic terminology. DESIGN AND PARTICIPANTS: We used data from the 2003 National Ambulatory Medical Care Survey (NAMCS), a nationally representative survey of 25,288 community-based outpatient visits in the United States. After each visit, patient medications were recorded on a survey encounter form by the treating physician or transcribed from office notes. MEASUREMENTS: Our main outcome measure was the frequency with which medications were recorded on the encounter form using their brand or generic names. RESULTS: For 20 commonly used drugs, the median frequency of brand name use was 98% (interquartile range, 81–100%). Among 12 medications with no generic competition at the time of the survey, the median frequency of brand name use was 100% (range 92–100%). Among 8 medications with generic competition at the time of the survey (“multisource” drugs), the median frequency of brand name use was 79% (range 0–98%; P < .001 for difference between drugs with and without generic competition). CONCLUSIONS: Physicians refer to most medications by their brand names, including drugs with generic formulations. This may lead to higher health care costs by promoting the use of brand-name products when generic alternatives are available
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