NordDesign 2020 August 11-14, 2020 Kgs. Lyngby, Denmark Insights for touchscreen interface guidelines for medical devices: A case study of a usability test Kamya Nagarajan1, Arlindo Silva1 & Hyowon Lee1 1Singapore University of Technology and Design [email protected] 1 Introduction 1.1.Usability of medical devices Usability is defined as ‘‘the extent to which a product can be used by specified users to achieve specified goals with effectiveness, efficiency and satisfaction in a specified context of use’’ (ISO 9241-11). Users in general are becoming less tolerant to poor design. In the context of medical device use, with a faster pace of patient treatment, the opportunity for use error is increased, placing further emphasis on the need for manufacturers to design devices to take such pressures into account(Ward and Clarkson 2004). Many adverse events in medicine are the result of poor interface design rather than human error(Fairbanks and Caplan 2004). In a medical setting, user groups are diverse, and so are the use cases. Clinicians, although considered to be expert users of medical devices, have a special need to interact concurrently with the on-screen UI(User Interface) and those physical parts the device may have, while paying attention to the patients. Use error caused by inadequate medical device usability has become an increasing cause of concern (ISO/IEC 62366-1:2015). Due to rising instances of user interface-related accidents and other incidents, FDA (U.S. Food and Drug Association) has begun to include human factors and usability engineering reviews in their approval process. In medical device design, the usability engineering process is intended to identify and minimize use errors and thereby reduce use-associated risks (ISO/IEC 62366-1:2015). 1.2. Touchscreen in medical devices Software controls are steadily replacing hardware controls across products, including in medical product domains. The reasons include flexibility, ability to handle variations in skills, language, functions, componentry and condition of use (Wilcox, 2005). Users possess mental models which include the models from products they use frequently. The prevailing touchscreen interfaces that users often encounter are personal hand-held devices and it appears to be a natural choice to inherit knowledge from hand-held devices while designing a touchscreen interaction in medical devices. The concepts and methods from the Human-Computer Interaction (HCI) and usability have a key role in healthcare. However, the requirement of any design is to fit the particular purpose. Designing such devices is often dependent on the skills and expertise of the designer and his or her view of the device users. With an increased number of devices in the market that are used by patients only in non- clinical environment, the device GUI (Graphic User Interface) must be straight forward and simple to use, without requiring extensive training (Altia Inc.). Despite the popular HCI guidelines and wide ranging literature, there are numerous studies on various UI that are found to be confusing and error prone. In a medical setting, these could lead to life-threatening situations. Medical device software development are regulated under ISO-62304, and hence it is critical that device software meets those criteria. 1 Unlike mobile apps which uses graphic oriented language such as Java, C++ and HTML5, medical devices are typically programmed in C. It is also to be considered that the device must be absolutely perfect and bug free before it can be submitted for its one- or two-year long FDA approval (Altia Inc.) 1.3. Usability test According to International Electrotechnical Commission, IEC 62366-1:2015, a usability test is a method for exploring or evaluating a user interface with intended users within a specified intended use environment. Usability testing is an important Human Factors Engineering methodology for healthcare industry. The main objective of a usability test is to identify as many usability problems as possible to enable design improvement. Observations made during the usability test are recorded in detail in the usability test report. These observations are usually about test details such as user groups, tasks, their outcomes. The usability test report is a salient source of information for developing usability design guidelines as the usability problems identified come directly from the target user groups. 2 Background Morita et al., (2016), compared the usability of 4 critical care ventilators from market leaders with 48 critical care respiratory therapists with 16 tasks on each ventilator. This study evaluates quantitatively the usability of the ventilators with touchscreens using NASA-TLX and PSSUQ scores. They mention that the qualitative data collected in the study indicates that the choices of interaction model of each ventilator (e.g., how to select information on the screen, adjusting settings and confirming) seem to interfere with the task completion and affect the users’ overall perception of the devices. But, they do not detail on those qualitative information to learn from the touchscreen interface problems on the existing devices. Zhang et al. (2019) analyzed data from the U.S. Food and Drug Administration (FDA) database related to the recall cases of UI software errors and came up with 20 categories of UI software errors. They report that as the data was specifically from FDA database alone, it may mis-represent the overall and typical usability problems on medical devices in general and that there is a need to advance their work to help medical device manufacturers develop more effective UI. Furniss et al., 2014, highlight through their study with an infusion pump pre-alarm problem that there is a need for HCI to develop concepts, models and tools that can more readily capture how the interactions at different levels of socio-technical system impact on the medical device design and use. As Ward and Clarkson (2004) note in an analysis of medical device-related errors, in the context of devices such as defibrillators and blood glucose meters, devices are being used in an increasingly wide range of settings, and thus we cannot always assume that a device user will have a certain level of training, skill or physical, social or cognitive ability. Acharya et al. (2010), in their case study on hospital bed user interfaces, found that the design of hospital bed control panels violate basic and well-known HCI principles. They also mention the below points, and to date, these points do not seem to contradict much with the current situation considering the amount of literature available in this topic. • HCI practitioners appear to be avoiding an important area; equally, the people working in the area seem unaware of HCI. 2 • HCI rarely discusses error and negative outcomes; much of the literature is about positive developments. • In the healthcare domain, most of the literature concentrates on clinical sequelae of adverse events not on the design or HCI issues that created the latent conditions for the error. • Adverse events are rarely explored from any perspective other than their clinical implications. Bitkina et al., (2020), in their review study on medical device usability mentions one of the future ergonomic challenges in medical technology as user-product interaction and more research is needed on the interaction between user and the medical device, as in the HCI field. Having a set of touchscreen interface guidelines considering knowledge in HCI and other domain, tailoring it specific to medical device applications, not only helps designers to consider all the relevant factors that influence the design, but also helps as a tool for medical device evaluation in hospitals in procurement decision-making (Ginsburg 2005; Fairbanks and Caplan 2004). The rationale behind this paper comes from the framework proposed in Tailor-made Human Factors and Usability guidelines by Nagarajan & Silva (2019), where usability testing reports are one of the internal sources of information that could contribute to develop Human Factors and Usability guidelines for medical device design(Fairbanks and Caplan 2004). Some device development processes may accommodate multiple instances of usability testing, while some may not; possible reasons for this lack of testing could be timeline or budget. The disadvantage of not being able to conduct multiple instances of usability testing, however, must not compromise device usability and learning from usability problems. This paper is an attempt to bridge the gap between designers and users, by including the context of various tasks in the usability testing of a medical device touchscreen. 3 Method Observation of outcomes from a usability test conducted for a medical device product with touchscreen interaction was used as the source of analysis reported in this study. The usability testing was conducted with 72 participants in diverse target user groups, namely clinicians(age: 22-65), caregivers(age: 22-75) and patients-as-users(age:15-75). The testing environments considered were a clinical and a home-use set-ups. The users were assigned specific tasks to perform a therapy using the medical device in different modes. The evidences from the outcomes that mainly relate to the use of a touchscreen UI of the device were considered for this study. The qualitative information in the notes/reports was analysed using thematic analysis and the insights drawn from multiple interface-related observations. The tasks were simulated in the device to verify the observation. Among several tasks assigned to the users, those tasks which contributed to usability-related improvement opportunities alone are further discussed in this paper. The insights made from the analysis were confirmed with the team for any conflict or mis-understanding of the problem. Table 1 shows the tasks distribution among three different user groups. The details of the task assigned to the user group, context and the outcome are explained in the next section. 3 Table 1: Task distribution among user groups S.No User Group No.