In the last post, we explored the organisational factors that influence patient safety. In this post we will take a look at another systemic determinant of patient safety – the design of healthcare equipment. It is clear that the wrongful use of healthcare equipment is a major threat to patient safety, and at the heart of this risk is the faulty design of the equipment. This is why Don Norman, in his book titled The Design of Everyday Things, pointed out that ‘all possible errors will occur’ in the use of any equipment, adding rather humorously that ‘if an error is possible, someone will make it‘. This realisation, Norman argued, should prompt designers to consider safety and the prevention of human error in the design of their equipment.
There are several considerations that go into the safe design of equipment, and these come under the remit of human factors engineering. According to John and Laura Lin Gosbee in the book Clinical Risk Management: Enhancing Patient Safety, human factors engineering is a concept that takes into account ‘human capabilities, limitations and characteristics‘ in the design of tools, machines and systems. This, they explained, implies that equipment should be ‘user-centred‘ and designed with the needs of the user in mind. Norman also referred to the usability features of the equipment when he said that equipment should be designed to ensure that the relevant parts are visible, and that how to use the equipment is self-explanatory.
In characterising the features of well-designed equipment, Norman emphasised the requirement for all equipment to be simple, standardised, flexible, and wherever possible, automated. He also highlighted the following safety-critical features of any equipment:
- Affordance: the equipment should signal how it should be used
- Natural mapping: the equipment should dispense with the need for diagrams, labels, or instructions
- Visibility: the equipment should give immediate feedback of the effect of using it
- Constraints: the equipment should prevent its wrongful use
- Forcing functions: the equipment should prevent later stages of use occurring if there are errors in the early stages
Before any medical equipment is put into use, John and Laura Lin Gosbee advised that it should be thoroughly evaluated. One technique they recommended for this was cognitive walkthrough, a process in which potential equipment users think and talk through how they would use the equipment. Another evaluation method they advocated was heuristic, a process in which a human factors or medical device specialist goes through a checklist of human factors principles which the equipment should possess. They also stressed that the following practical issues should be addressed whenever any equipment is being designed:
- How long it takes to learn to set up and operate the equipment
- They types and frequency of errors it gives rise to
- The effect of time pressure on performance when using it
- The presence or absence of prompts and feedback by the device
- The ease of understanding the equipment’s displays
- The memory load that is needed to operate the equipment
Patrice Spath also explored equipment safety design in her book Error Reduction in Health Care. Some of the features of well-designed equipment she highlighted were: clear readable displays, accessible and labelled controls, and time efficiency. Because no design can be completely free of erroneous use, Normal recommended the following error-mitigating principles when designing any equipment:
- Errors should be easy to detect
- Errors should have minimal consequences
- The effects of errors should be reversible
In the next post we will conclude our review of the systemic foundations of patient safety with a look at the drivers and remedies of organisational failure.