Prolonged time to alarm in infusion devices operated at low flow rates.

OBJECTIVE: To evaluate the time to occlusion alarm for peristaltic infusion devices used in Toronto adult critical care units. DESIGN: Cross-sectional study. SETTING: Biomedical engineering departments of four Toronto teaching hospitals. SUBJECTS: Twenty peristaltic infusion devices (five Sigma 8000-plus, five Graseby 3000, five Baxter Colleague, and five Alaris 7230B). INTERVENTIONS: None. MEASUREMENTS: Time to occlusion alarm at flow rates of 2, 10, and 100 mL/hr at a full range of available pressure thresholds for occlusion detection, and with commonly used tubing sets. MAIN RESULTS: At default (mid-range) pressure thresholds, mean (SD) time to occlusion alarm was 0.3 (0.1) min at a flow rate of 100 mL/hr, 2.3 (0.5) min at a flow rate of 10 mL/hr, and 11.7 (3.1) min at a flow rate of 2 mL/hr. CONCLUSIONS: Time to occlusion alarm in peristaltic infusion devices is long at low flow rates. Patients receiving important medications with short half-lives at low flow rates could experience clinically important interruptions in treatment. Time to occlusion alarm at high flow rates is short, which could lead to excessive alarms and "alarm mistrust" by clinical staff.

Human factors in action: getting "pumped" at a nursing usability laboratory.

We describe our experience with a Nursing Usability Laboratory, where human factors design principles were applied to common nursing procedures. Our first step was to develop a human factors usability checklist. We then used this checklist while observing 11 nurses completing two standardized tasks on a simulated patient: (1) programming an insulin infusion and (2) programming a heparin infusion. We found that a usability checklist can help to uncover systematic error-provoking conditions in nursing tasks, that immediate improvements can be made in nursing training and practice and that participant nurses found the process useful. This paper will be of interest to any hospital seeking to enhance safety by applying human factors design principles.