While a programming error in setting the drug concentration carries the most serious threat to patient safety, the most frequent programming error with the existing interface was in setting the mode, accounting for 11 of the 29 errors. Nurses were observed to be quite accustomed to setting the mode to 'PCA only', the mode typically prescribed for patients at The Toronto Hospital where the study was carried out. When faced with different programming tasks, such as prescriptions for 'Continuous' and 'PCA+ Continuous' modes, nurses often made an incorrect mode selection, but eventually recovered from 9 of the 11 errors. The most obvious explanation for this type of programming error lies in the characteristics of the subject population: the nurses' prior training and experience with the Abbott PCA interface created the propensity to commit these mode selection errors. However, the new interface appeared to be effective in overcoming subjects' habits, recording only 3 such mode errors, all of which were eventually corrected. That the new interface is less prone to mode errors is likely a result of it's menu display, providing the user with a global view of options for mode selection on a single screen.

The most common error with the new interface involved the bolus dose. Typically, nurses neglected to administer a bolus dose during the programming task, an error that is not unexpected since it is uncommon for nurses in the recovery room at The Toronto Hospital to administer a bolus dose during programming as was required of them during the experiment. This aspect of the experimental conditions may have played a role in the frequent occurrence of bolus dose errors.
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Contact: Lois Smith
hfes@compuserve.com
310-394-1811
Human Factors and Ergonomics Society
1-Feb-1999