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Steven Day

Publications and source records attributed to Steven Day.

4 recordsLinked to original sources
PubMed2003

Excess mortality in remote symptomatic epilepsy.

BACKGROUND: Published estimates of excess mortality associated with epilepsy vary greatly. How much, if any, of the excess is attributable to the seizures themselves as opposed to an underlying condition causing the epilepsy is not clear from the literature. This article offers evidence that epilepsy per se is associated with excess mortality. The excess varies according to severity and frequency of seizures. MATERIALS AND METHODS: The authors studied mortality rates of developmentally disabled persons in California with and without epilepsy. In order to focus on the effect on mortality risk of epilepsy per se, they included only persons with good motor function (able to walk and climb stairs) and at worst moderate mental retardation (MR). The data were 506,204 person-years and 1523 deaths among 80,682 California subjects of age 5 to 65 years during the 1988-1999 study period. Mortality rates for persons with epilepsy were compared to rates for persons with no history of epilepsy. RESULTS: Mortality rates were higher for persons with epilepsy than for those without. Excess death rates (EDRs) varied according to type and frequency of seizures. Combined EDRs were 6 (deaths per 1000 person-years) for persons with recent (< 12 months) history of status epilepticus, 5 for recent history of generalized tonic-clonic (GTC) seizures, 3 for recent history of seizures but no recent GTC seizures, and less than 1 for a history of seizures but no recent events. CONCLUSIONS: The data presented here are evidence that epilepsy per se is associated with increased mortality. The EDRs reported here may be better measures of excess mortality due to epilepsy than previously published estimates.

Adolescent↗
PubMedDate not supplied

Computational design and experimental testing of a novel axial flow LVAD.

Thousands of cardiac failure patients per year in the United States could benefit from long-term mechanical circulatory support as destination therapy. To provide an improvement over currently available devices, we have designed a fully implantable axial-flow ventricular assist device with a magnetically levitated impeller (LEV-VAD). In contrast to currently available devices, the LEV-VAD has an unobstructed blood flow path and no secondary flow regions, generating substantially less retrograde and stagnant flow. The pump design included the extensive use of conventional pump design equations and computational fluid dynamics (CFD) modeling for predicting pressure-flow curves, hydraulic efficiencies, scalar fluid stress levels, exposure times to such stress, and axial fluid forces exerted on the impeller for the suspension design. Flow performance testing was completed on a plastic prototype of the LEV-VAD for comparison with the CFD predictions. Animal fit trials were completed to determine optimum pump location and cannulae configuration for future acute and long-term animal implantations, providing additional insight into the LEV-VAD configuration and implantability. Per the CFD results, the LEV-VAD produces 6 l/min and 100 mm Hg at a rotational speed of approximately 6300 rpm for steady flow conditions. The pressure-flow performance predictions demonstrated the VAD's ability to deliver adequate flow over physiologic pressures for reasonable rotational speeds with best efficiency points ranging from 25% to 30%. The CFD numerical estimations generally agree within 10% of the experimental measurements over the entire range of rotational speeds tested. Animal fit trials revealed that the LEV-VAD's size and configuration were adequate, requiring no alterations to cannulae configurations for future animal testing. These acceptable performance results for LEV-VAD design support proceeding with manufacturing of a prototype for extensive mock loop and initial acute animal testing.

Animals↗