Development and preliminary usability evaluation of VISCalc, a bedside calculator for the Vasoactive-Inotropic Score: a brief research report

Abstract Background The Vasoactive-Inotropic Score (VIS) quantifies pharmacological hemodynamic support after pediatric cardiac surgery, but bedside calculation requires multi-step manual arithmetic. We describe the development and preliminary evaluation of VISCalc, a low-cost web-based VIS calculator. Methods VISCalc was developed in sequential phases in a pediatric cardiac intensive care unit in São Paulo, Brazil. Usability was assessed with the System Usability Scale (SUS) among 15 physicians. Arithmetic fidelity was verified in ten retrospective clinical cases independently calculated by three blinded evaluators and in 12 predefined synthetic cases covering all six VIS drugs. Results The mean SUS score was 73.3 ± 8.5, indicating good usability. VISCalc returned the correct VIS in all ten clinical cases and 12 synthetic cases, whereas 29/30 manual calculations (96.7%) were correct. The tool stores successive VIS values and displays a time-course graph without requiring patient identification. Direct out-of-pocket expenses were below US$450. Conclusion A structured, low-cost development process produced a bedside VIS calculator with good perceived usability and exact arithmetic fidelity. Its effects on calculation time, errors during routine use, and clinical outcomes should be evaluated prospectively.