Objective: To identify factors which influence the choice of nurses to use automated collection of IV pump data from a prototype Medical Information Bus. Design: Observational study for a duration of three and one-half months. Setting: Four intensive care units, each with different missions, in an adult hospital. Subjects: One hundred fifty-eight registered nurses including both full and part time. Measurements and Main Results: Data were collected from the hospital information system about infusion orders including the type of medication, the number of rate changes, the method of documenting rate changes and the infusion methods. The method of documentation for infusion rate changes was defined as either automated, using a prototype Medical Information Bus (MIB), or manual, using the keyboard at a bedside computer terminal. The method of infusion was defined as either straight gravity feed without an IV pump (‘no pump’), infusion using a pump but without connection to the hospital information system (‘pump only’) and infusion using a pump which was connected to the hospital information system using a prototype Medical Information Bus (‘automated’). A total of 22,199 rate changes were documented during the study period and of those, 22,055 (99.35%) used the ‘automated’ method. Medications with the highest average rate change per single container were; Nitroprusside Sodium (9.50), Epinephrine (9.08) and Epoprostenol (7.50). Conclusions: The nurses used automated IV pump data acquisition with medications which required frequent rate changes.