title: The usability of ventilators: a comparative evaluation of use safety and user experience.
abstract: BACKGROUND
  The design complexity of critical care ventilators (CCVs) can lead to use errors and patient harm. In this study, we present the results of a comparison of four CCVs from market leaders, using a rigorous methodology for the evaluation of use safety and user experience of medical devices.
  
  
  METHODS
  We carried out a comparative usability study of four CCVs: Hamilton G5, Puritan Bennett 980, Maquet SERVO-U, and Dräger Evita V500. Forty-eight critical care respiratory therapists participated in this fully counterbalanced, repeated measures study. Participants completed seven clinical scenarios composed of 16 tasks on each ventilator. Use safety was measured by percentage of tasks with use errors or close calls (UE/CCs). User experience was measured by system usability and workload metrics, using the Post-Study System Usability Questionnaire (PSSUQ) and the National Aeronautics and Space Administration Task Load Index (NASA-TLX).
  
  
  RESULTS
  Nine of 18 post hoc contrasts between pairs of ventilators were significant after Bonferroni correction, with effect sizes between 0.4 and 1.09 (Cohen's d). There were significantly fewer UE/CCs with SERVO-U when compared to G5 (p = 0.044) and V500 (p = 0.020). Participants reported higher system usability for G5 when compared to PB980 (p = 0.035) and higher system usability for SERVO-U when compared to G5 (p < 0.001), PB980 (p < 0.001), and V500 (p < 0.001). Participants reported lower workload for G5 when compared to PB980 (p < 0.001) and lower workload for SERVO-U when compared to PB980 (p < 0.001) and V500 (p < 0.001). G5 scored better on two of nine possible comparisons; SERVO-U scored better on seven of nine possible comparisons. Aspects influencing participants' performance and perception include the low sensitivity of G5's touchscreen and the positive effect from the quality of SERVO-U's user interface design.
  
  
  CONCLUSIONS
  This study provides empirical evidence of how four ventilators from market leaders compare and highlights the importance of medical technology design. Within the boundaries of this study, we can infer that SERVO-U demonstrated the highest levels of use safety and user experience, followed by G5. Based on qualitative data, differences in outcomes could be explained by interaction design, quality of hardware components used in manufacturing, and influence of consumer product technology on users' expectations.
authors.affiliation: Healthcare Human Factors, Techna Institute, University Health Network, Toronto, Canada.|Institute of Health Policy, Management and Evaluation, University of Toronto, Toronto, Canada.
authors.forename: Plinio P
authors.initials: PP
authors.lastname: Morita
authors.affiliation: Healthcare Human Factors, Techna Institute, University Health Network, Toronto, Canada.
authors.forename: Peter B
authors.initials: PB
authors.lastname: Weinstein
authors.affiliation: Healthcare Human Factors, Techna Institute, University Health Network, Toronto, Canada.
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Flewwelling
authors.affiliation: Healthcare Human Factors, Techna Institute, University Health Network, Toronto, Canada.
authors.forename: Carleene A
authors.initials: CA
authors.lastname: Bañez
authors.affiliation: Healthcare Human Factors, Techna Institute, University Health Network, Toronto, Canada.
authors.forename: Tabitha A
authors.initials: TA
authors.lastname: Chiu
authors.affiliation: Healthcare Human Factors, Techna Institute, University Health Network, Toronto, Canada.
authors.forename: Mario
authors.initials: M
authors.lastname: Iannuzzi
authors.affiliation: Healthcare Human Factors, Techna Institute, University Health Network, Toronto, Canada.
authors.forename: Aastha H
authors.initials: AH
authors.lastname: Patel
authors.affiliation: Healthcare Human Factors, Techna Institute, University Health Network, Toronto, Canada.
authors.forename: Ashleigh P
authors.initials: AP
authors.lastname: Shier
authors.affiliation: Healthcare Human Factors, Techna Institute, University Health Network, Toronto, Canada. Joe.Cafazzo@uhn.ca.|Institute of Health Policy, Management and Evaluation, University of Toronto, Toronto, Canada. Joe.Cafazzo@uhn.ca.|Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, Canada. Joe.Cafazzo@uhn.ca.
authors.forename: Joseph A
authors.initials: JA
authors.lastname: Cafazzo
mesh_terms: D003422:Critical Care / Q000379:methods / Q000592:standards; D004867:Equipment Design / Q000592:standards*; D006282:Health Personnel / Q000523:psychology*; D006801:Humans; D007362:Intensive Care Units / Q000458:organization & administration; D061214:Patient Safety / Q000592:standards*; D012121:Respiration, Artificial / Q000295:instrumentation; D012122:Ventilators, Mechanical / Q000706:statistics & numerical data*
keywords: Comparative study; Critical care; Human factors and ergonomics; Mechanical; Medical device design; Patient safety; Ventilator