Optimizing the User Interface of a First-Aid App: A “Realistic” Usability Study with the Smartphone Application “Defi Now!”

Millions of applications (apps) for smartphones exist and are gaining popularity since the introduction of smartphones in 2005. But, merely a small number of these applications were developed in support of first aid, in particular the use of a defibrillation device. Such apps support passers-by witnessing an emergency situation or allow refreshment of basic first-aid knowledge. Moreover, they inform about publicly available automatic external defibrillators (AEDs) and allow charting new devices. After a brief survey of various types of first-aid apps, we consider the question to what extent these apps are really helpful in emergency cases. To begin answering this question, we report the result of a usability study with 74 test subjects who used the “Defi Now!” app. In order to simulate “realistic” conditions where the user is agitated—as is the case when rescuing a person—, we induced fear by a psychologically recommended method. We discuss advantages and disadvantages of the app based on data from our questionnaires and the video material we collected. Basically, the app was judged to be very helpful as a first-aid support tool. Nevertheless, observations during the study suggested several software-ergonomic improvements.