just screen and buttons when talking about a medical device all kinds

introduction to usability engineering and iec 62366-1 you'll find it on medicaldevicehq.com usability engineering if you want more premium medical device content don't forget to click the subscriber notifications button so you don't miss out usability engineering is about understanding who uses the device the tasks of the users the environment in which they will use it and designing a great user interface there are directly two terms i would like to introduce to you the first and probably the most important one in the whole usability engineering work is user a user is simply the person who is interacting with the medical device and the second term when talking about a great user interface is of course user interface and in the medical world the user interface actually includes more than you might think the user interface means so much more than

accompanying documentation and basically everything that the user can interact with needs to be considered a user interface it even includes auditory signals and the instructions for use so where does the usability engineering process start it starts with the preparation of a used specification the use specification is a document that includes all the information about your users you can imagine it as an extended form of the intended use and getting information right is really crucial for the success of your product that becomes really clear if you have a look at this example imagine you are talking about a glucose measuring device if it is used in a home use environment by a young child you will need to prepare a different device compared to a device that will be used by a professional caregiver in a hospital environment even more the same could be true if you're looking only at home use environment imagine you're comparing a device that will be used only by kids with one that is used only by elderly people they will most probably be designed completely differently to make sure that your device will be good and safe you have to take great care of identifying the right user profiles and writing down all the information that makes this user so special and please remember this not only includes characteristics of the person but also characteristics of the tasks and the use environment and this is the starting point for the usability engineering process based on what the use and the users are like you should analyze what could go wrong with regards to the safety of the user interface this is similar to identifying hazards or answering questions relating to the safety of the device that many would be doing as part of risk management process according to the iso 14971 standard let's have a look at the graphic from the standard again as you can see safety plays a major role in usability engineering for medical devices in the original process looking at things that could go wrong makes a total of three steps i just group them together for the sake of simplicity and when speaking about things that could go wrong one term that comes up is the term use error the term use error has a very broad definition because you could say that a use error happens every time a human and the machine misunderstands each other not every use error will lead to hazardous situation far from but some use errors may and those are the ones usability engineering is focusing on the formal definition of use error is a use error is defined as a user action or lack of such an action while using a medical device that leads to different results as intended by the manufacturer or expected by the user of the device typical examples of a use error could be a nurse who accidentally pulls out the cable of the sensor of a monitoring device without noticing it or it could be a healthcare professional who touches a sterile tissue with his or her bare fingers before applying it to wound but it could also mean that someone accidentally connects a cable to the wrong part of a medical device and the signal is not transduced correctly as you can see there are a lot of different potential use errors and please note it's not called the user error if you think so you won't pass the final exam of this course because user error implies it's the user's fault but it's most definitely not always the user's fault when there's a use error another important term that is highly relevant when talking about things that could go wrong is the term hazard-related use scenarios the term can be a bit challenging for those that were not always working with risk management therefore i'd like to introduce you to it a hazard-related use scenario is a hazardous situation that you occurred as a result of a use error and we already discussed what use errors and the hazard related use scenarios are the things you need to identify and document because you will need them in the next step because then based on the identified use error and on what could go wrong you decide which things you should evaluate in the very end of your product development that is to identify hazard-related use scenarios that will be included in your summative evaluation in the end to ensure that your medical device is safe providing or verifying that the device is safe is a must because it is a general principle in both risk management and design control so you have to check whether your risk control attempts were successful and the success is checked by the summative evaluation but don't worry i will explain what a summative evaluation is in a few moments now that we've gone through the first analysis it's time to specify requirements on the user interface when implemented those requirements should reduce the risk that we previously identified to make sure that when we do the final evaluation of the device the user will not end up in a situation where the risk is unacceptable from a risk management point of view you could say that these requirements are risk control measures and that is the great thing about starting with the risk in mind you now know which user interface requirements you need to include to be able to reduce those risks nevertheless i would like to encourage you to not only include requirements that make a safe device but also think about the requirements that come to mind when thinking about the user environment and the task of your users so those requirements that would really make a great device that everybody is delighted to use next you need to implement the requirements you decided on in the previous step by designing the device and its user interface while you do you should check that you are on the right track that is really important because from my experience you won't get the design right on the first try especially when you're designing a new product there's a term for making tests along the way and that is called formative evaluation let's look at the term formative evaluation it's a quite challenging term to remember this term is actually not only used in usability engineering but also in teaching and it means almost the same thing in both contexts remember i say that we are checking that we're on the right track which is also what you would do in teaching when you're doing formative evaluation in fact when you take this course and you go through the checkpoint quizzes this is also kind of formative evaluation having said that i hope i've created a few memory hooks for you to remember the term formative evaluation so what could a formative evaluation be like it could be that you show early wireframes to users to see where they would click you could be making tests with prototypes to see how people interact with your device or you could do focus groups or surveys a formative evaluation is basically any method you can come up with that would solicit feedback on your user interface in its simplest form it's just to ask if someone understands it or what the symbol should be like on the device more advanced formative evaluations include testing in an environment that is as real as possible with multiple users and a product that is similar to the final one the amount of work you do in this field depends on whether the product is brand new or not and the severity of the harm that could occur as a result of failure in the user interface if you are for example making a new iteration of an already existing product you are likely to do very little formative evaluation or even little usability engineering at all whereas if you are developing a brand new high risk product that trusts humans to operate it correctly you are going to invest a lot more time and resources into this field what if you find that you're not on track well then you need to iterate on the design and approve this is how you proceed with the development until you find in your last formative test that just nothing to improve anymore after having implemented a user interface according to the requirements you have defined and evaluating it along the way it's time to do the final summative evaluation the summative evaluation should demonstrate that the user does not end up in a situation with an unacceptable risk as a result of poor usability before explaining the summative evaluation please note it is not the same thing as design validation the design validation will focus on showing that the user needs have been met while the summative evaluation is about showing that the user interface is safe there might be a small overlap in terms of how you do the testing but they do have different purposes so summative evaluation is testing the usability under conditions of simulated use it should also be done using production units or equivalent devices from the point of view once again it's similar to design validation but remember that the purpose is different lastly all the documentation and records you have created throughout the usability engineering process will be referred to as the usability engineering file that was the usability engineering process in a nutshell if you want to learn more about usability engineering you can sign up for my online course introduction to usability engineering and iec 62366-1 on medicaldevicehq.com thanks for watching and stay tuned for the next