Drug dosages and weight calculations are a well understood source of serious errors and all manner of adverse outcomes including death. This is particularly noted in inexperienced, fatigued, panicky and high workload situations.

Mathematical skills can vary considerably among clinical staff and while a base level of numeracy is usual present various causes of problems can occur including the use of an incorrect formulae, miscalculation of a formula, legibility of the original order or subsequent directions and lack of checking. 

None of these errors are necessarily eradicated in moving to a computerised solution be it handheld or spreadsheet process.

All the issues of poor software design live synergistically within new clinical information systems along with the pre-existing causative factors.

Poor software design may not lock in constants such as weight or dosage rates allowing them to be over-written by mistake, poor mouse or pen focus control and particularly on the latest micro and touch screens simply inaccurate hand eye coordination.  Software and hardware focus control is essential as following completing one entry, movement to another cell by mouse may leave the focus on the preceding entry and unanticipated changes may result and may not be picked up by the inexperienced or casual user.  Having typed a couple of key strokes and noting no change they click on the new entry point not realising the few key entries have gone into the preceeding entry.

 ”Wrong data in wrong cell” – a new catch cry or defense?

Windows is particularly prone to the focus-scrolling error where you can place your cursor on a cell and scroll through alternatives and then rather than using your mouse to move down to the next cell and click where you intend to type you forget to and start typing, meanwhile off screen an other cell is changing unbeknown to the user and even if known may not be able to be detected if the sheets or templates are complex.

Saskia N de Wildt, Ron Verzijden, John N van den Anker and  Matthijs de Hoog in “Information technology cannot guarantee patient safety” ( BMJ, 2007:334:851-2) looked at some of these issues.