Pump priming: Dr Judy Bowen and Professor Steve Reeves say medical infusion pumps are a prime candidate for formal software modelling techniques.
“Hospitals don’t let the manuals for these devices get anywhere near their staff,” says Dr Judy Bowen, an expert on the design of safety-critical interactive systems in the Department of Computer Science at the University of Waikato.
“The Waikato District Health Board develops some of its own training materials and uses those developed by pump distributors – and when you look at how these devices work, you can understand why.”
Dr Bowen and Professor Steve Reeves of the Formal Methods Group are working with DHB’s Biomedical Division at Waikato Hospital to “reverse engineer” some of the pumps used in the hospital.
Dr Bowen is focusing on the user interface by mathematically modelling the instructions in the manual and seeing what divergences there are with the device’s actual behaviour.
“We’ve found some interesting and unexpected behaviours,” she says. “For example, when you hit the on/off button during set-up, the pump reverts to its initial settings, so the operator would then need to reset the infusion rate, volume and time. But there’s nothing in the manual to warn you about this.”
Any user struggling to set up a smart TV system or home wireless network will sympathise. The problem, says Dr Bowen, lies in the process typically used in software development.
“Once the requirements are developed, they’re given to the software developer and the technical writer, and then they go away to their separate corners and never speak again.
“But there’s an alternative way to develop software – and that’s by using mathematical modelling. We want to find out if we can take our formal models and use those to derive the manual. That way we can guarantee the two will match.”
Josh Farrington, biomedical engineering manager at Waikato Hospital, says the project has already come up with some useful insights for the DHB.
“Judy’s modelling revealed some surprising functional discrepancies between the user manual and how the infusion device actually operates,” he says. “From what we’ve seen, using formal modelling techniques like these to derive user and service manuals would provide us with more accurate information for safer operation of the device.”
Formal software modelling is already being used in safety-critical areas such as aerospace, networks, mass transit systems and car manufacturing, and Professor Reeves says there’s no reason why it can’t be applied to the relatively young medical device industry.
“With formal modelling, we can guarantee that the device will do exactly what it’s meant to do,” he says. “There are none of the bugs you inevitably get with conventional software development because you can use the model to generate exhaustive tests.
“We’ve got the means to add failsafe software to these small, high-value devices, which could open the door to a lucrative niche export industry for New Zealand.”
Back at Waikato Hospital, the researchers are now using their initial findings to advise on where and how the devices can be safely used.
“These pumps are expensive, upwards of $2,500 each, so while they’re bought in for a specific purpose, the DHB typically will want to use them in a variety of environments,” says Dr Bowen.
“For example, hospital staff may want to know if they can use a particular pump in a rescue helicopter situation. So we can incorporate environmental aspects into our models – which will allow us to check if the alarm system is operational in a very noisy, vibrating environment like a helicopter.”
For more stories on research and innovation at the University of Waikato, see the latest issue of re:think.