Browsing by Author "Halperin, Mitchell L."

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    Bolus administration of intravenous glucose in the treatment of hyperkalemia : a randomized controlled trial
    (Karger, 2014-02) Chothia, Mogamat-Yazied; Halperin, Mitchell L.; Rensburg, Megan A.; Hassan, Mogamat Shafick; Davids, Mogamat Razeen
    Background: Hyperkalemia is a common medical emergency that may result in serious cardiac arrhythmias. Standard therapy with insulin plus glucose reliably lowers the serum potassium concentration ([K + ]) but carries the risk of hypoglycemia. This study examined whether an intravenous glucose- only bolus lowers serum [K + ] in stable, nondiabetic, hyperkalemic patients and compared this intervention with insulin-plus-glucose therapy. Methods: A randomized, crossover study was conducted in 10 chronic hemodialysis patients who were prone to hyperkalemia. Administration of 10 units of insulin with 100 ml of 50% glucose (50 g) was compared with the administration of 100 ml of 50% glucose only. Serum [K + ] was measured up to 60 min. Patients were monitored for hypoglycemia and EKG changes. Results: Baseline serum [K + ] was 6.01 ± 0.87 and 6.23 ± 1.20 mmol/l in the insulin and glucose-only groups, respectively (p = 0.45). At 60 min, the glucose-only group had a fall in [K + ] of 0.50 ± 0.31 mmol/l (p < 0.001). In the insulin group, there was a fall of 0.83 ± 0.53 mmol/l at 60 min (p < 0.001) and a lower serum [K + ] at that time compared to the glucose-only group (5.18 ± 0.76 vs. 5.73 ± 1.12 mmol/l, respectively; p = 0.01). In the glucose-only group, the glucose area under the curve (AUC) was greater and the insulin AUC was smaller. Two patients in the insulin group developed hypoglycemia. Conclusion: Infusion of a glucose-only bolus caused a clinically significant decrease in serum [K + ] without any episodes of hypoglycemia.
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    Development and evaluation of a multimedia e-learning resource for electrolyte and acid-base disorders
    (American Physiological Society, 2011-10) Davids, MR; Chikte, Usuf M. E.; Halperin, Mitchell L.
    This article reports on the development and evaluation of a Web-based application that provides instruction and hands-on practice in managing electrolyte and acid-base disorders. Our teaching approach, which focuses on concepts rather than details, encourages quantitative analysis and a logical problem-solving approach. Identifying any dangers to the patient is a vital first step. Concepts such as an “appropriate response” to a given perturbation and the need for electroneutrality in body fluids are used repeatedly. Our Electrolyte Workshop was developed using Flash and followed an iterative design process. Two case-based tutorials were built in this first phase, with one tutorial including an interactive treatment simulation. Users select from a menu of therapies and see the impact of their choices on the patient. Appropriate text messages are displayed, and changes in body compartment sizes, brain size, and plasma sodium concentrations are illustrated via Flash animation. Challenges encountered included a shortage of skilled Flash developers, budgetary constraints, and challenges in communication between the authors and the developers. The application was evaluated via user testing by residents and specialists in internal medicine. Satisfaction was measured with a questionnaire based on the System Usability Scale. The mean System Usability Scale score was 78.4 ± 13.8, indicating a good level of usability. Participants rated the content as being scientifically sound; they liked the teaching approach and felt that concepts were conveyed clearly. They indicated that the application held their interest, that it increased their understanding of hyponatremia, and that they would recommend this learning resource to others.
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    Effect of improving the usability of an e-learning resource : a randomized trial
    (HighWire, 2014-06) Davids, Mogamat Razeen; Chikte, Usuf M. E.; Halperin, Mitchell L.
    Optimizing the usability of e-learning materials is necessary to reduce extraneous cognitive load and maximize their potential educational impact. However, this is often neglected, especially when time and other resources are limited. We conducted a randomized trial to investigate whether a usability evaluation of our multimedia e-learning resource, followed by fixing of all problems identified, would translate into improvements in usability parameters and learning by medical residents.
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    Usability testing of a multimedia e-learning resource for electrolyte and acid-base disorders
    (Wiley Online Open, 2013-04) Davids, M. R.; Chikte, Usuf M. E.; Grimmer-Somers, Karen; Halperin, Mitchell L.
    The usability of computer interfaces may have a major influence on learning. Design approaches that optimize usability are commonplace in the software development industry but are seldom used in the development of e-learning resources, especially in medical education. We conducted a usability evaluation of a multimedia resource for teaching electrolyte and acid-base disorders by studying the interaction of 15 medical doctors with the application. Most of the usability problems occurred in an interactive treatment simulation, which was completed successfully by only 20% of participants. A total of 27 distinct usability problems were detected, with 15 categorized as serious. No differences were observed with respect to usability problems detected by junior doctors as compared with more experienced colleagues. Problems were related to user information and feedback, the visual layout, match with the real world, error prevention and management, and consistency and standards. The resource was therefore unusable for many participants; this is in contrast to good scores previously reported for subjective user satisfaction. The findings suggest that the development of e-learning materials should follow an iterative design-and-test process that includes routine usability evaluation. User testing should include the study of objective measures and not rely only on self-reported measures of satisfaction.