APPLYING HUMAN-FACTORS TO THE DESIGN OF MEDICAL EQUIPMENT - PATIENT-CONTROLLED ANALGESIA

Objective. Medical instruments commonly have poorly designed user inte rfaces that promote human errors with life-threatening consequences. T he primary hypothesis of this study was that a specific user interface could be made safer and more efficient ii redesigned using human fact ors techniques and principles. Methods. The user interface of a commer cially available patient-controlled analgesia (PCA) pump, the Abbott L ifecare 4100 PCA Plus II infuser, was evaluated using a cognitive task analysis of bench tests and field observations. Based on this analysi s, the user interface was redesigned. Important elements of the new de sign include a dialog structure with fewer steps, a dialog overview sh owing the user's location in the programming sequence, better command feedback, easier error recovery, and clearer labels and messages. The changes were evaluated by comparing a computer prototype of the new in terface with a computer simulation of the old one. Twelve student nurs es performed six programming tasks with each interface. Task completio n time, number of errors, and subjective mental workload were collecte d for each trial. Results. The results showed significantly Easter pro gramming times (F(1,11) = 6.85, P < 0.025), lower mental workload rati ngs (chi(2)(1) = 4.45, p < 0.025, one-tailed), and fewer errors (chi(2 )(1) = 3.33, p < 0.05, one-tailed) with the new interface. Conclusion. Adopting a human factors approach to redesigning the PCA interface le d to significantly Easter, easier, and more reliable performance. Thes e findings have important implications for improving the design of oth er computer-based medical equipment.