Interruption during medication administration is a significant patient safety concern, especially during the administration of high risk medications. Specifically, patient-controlled analgesia (PCA) devices are frequently associated with adverse events and have a four-fold increased risk of patient injury compared to non-PCA related adverse events. While the nature and frequency of interruptions have been established for nurses' medication processes, the impact of interruption frequency on nurses' PCA interaction has not been fully described or measured. The purpose of this study is to quantify the impact of interruption frequency on nurses' performance, satisfaction, and cognitive workload in a simulated setting using a complex system-interaction approach. This study will employ an experimental within-groups design. Registered nurses (RN) will be recruited from Florida hospitals and will complete PCA programming tasks in a simulated nursing environment for each of three conditions where interruption frequency will be pre-determined (no interruption/baseline, moderate, and high interruption frequency), using both auditory and visual distracters. Established human factors usability measures will be completed for each of the three environments. RN performance will be video-recorded with time-stamp then analyzed for performance measures of efficiency (task time) and effectiveness (accuracy). RNs will complete a user satisfaction questionnaire (QUIS®) and cognitive workload assessment (NASA-TLX). The research questions will be answered using repeated measures analysis of variance with (RM-ANOVA). The use of a human factors systems approach and measures are novel to the study the impact of interruption on nurses' PCA interactions. The proposed collaboration between the NSU College of Nursing and Health Care Sciences, and an experienced clinical outcomes researcher has the potential to contribute to both nursing and patient safety literature. The results of this study can be used to inform stakeholders on the impact of RN interruption on medication errors and as a springboard for further research in this area.