Usability helps deliver the right information clearly and effectively... so you’re ready to save lives

HFI’s usability review ranks new LIFEPAK® 1000 defibrillator as the most usable out of six devices evaluated

SUMMARY Defibrillators are used in high stress environments, and minimizing delays in patient care is critical. Yet the locale in which patients require treatment can range from hospital wards to highly public places. Thus, overall ease of use is key in assuring a successful patient resuscitation by rescue personnel. This usability review seeks to test the usability of the LIFEPAK 1000 in multiple use and maintenance scenarios relative to other defibrillators in the market. In comparison to six other defibrillators on the market (Philips FR2+, Zoll AED Plus, Welch Allyn AED 20 and AED 10, and Cardiac Science/ Quinton G3Pro), the LIFEPAK 1000 ranks highest overall in professional first responder usability.

USABILITY REVIEW – DEFINITION Two highly experienced human factors engineers evaluated six defibrillators to determine their usability. Human factors engineers are professionals trained in the principles and methodology of what makes a device intuitive for users of various backgrounds. The name of the profession derives from focusing on the characteristics of the human, or human factor, in the two-way interaction that occurs when a person uses technology. In this study, two human factors engineers reviewed what professional first responders experience with each defibrillator and identified usability strengths and weaknesses. This method is called an Expert Review. It draws on previous observation of hundreds of users, a deep understanding of principles underlying humans interacting with devices, and an equally deep understanding of human cognitive processes.

PROCEDURE The study was comprised of three steps:

1. Identification of what makes a defibrillator usable.

LIFEPAK 1000 defibrillators are designed for "professional first responders”—the first medical professionals to arrive on the scene of a sudden

cardiac arrest, be they paramedics, firefighters, or nurses. The LIFEPAK 1000 was also tested, however, for how well the lay person with minimal training would interact with the device. Thus assuring a good user experience overall is a more rigorous process.

Due to the situation in which the device is used, a design that is highly usable will inspire user confidence, minimize excessive sensory input, also referred to as cognitive load, and assure caregivers focus on the patient more than on the device. A good design provides only the information needed for users to take the next action in a treatment sequence confidently and correctly.

In contrast, a poorer design creates too much cognitive load by causing confusion and “extra” thinking. This ultimately decreases caregivers’ accuracy and speed, increasing the hands-off time in patient care which could have dire consequences. Causes include:

• Unfamiliar terminology, • Mismatch between auditory and visual prompts, • Pictograms that are difficult to translate into a sequence of actions, • Too much information to wade through, • Treatment button that is difficult to find.

Critical design aspects evaluated for all products included:

• Clarity of design. This applies to instructions on all surfaces and modalities (case design, electrode insertion, interaction area and physical button affordance, size, clarity, and quality of visual display, battery insertion and removal). This also applied to electrode pad clarity of use intent and labeling. E.g., Does the device design easily allow rescuers to focus on patient care rather than the device? Is the display easy to understand and translate into action? Are buttons easily distinguished from informative graphics? Is it clear where and how to place electrodes on the patient?

• Whether the defibrillator did all work possible for the user to minimize opportunity for error. E.g.,

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Are all attachments easy to find and connect? Is there sufficient time to respond to the auditory instructions? Are prompts clear and concise?

• Provision of feedback about the current state of the device so that users know that the right thing is happening. E.g., Can users tell when the device was monitoring, charging to shock, etc.

• Treatment sequence. With changing guidelines, clarity of treatment sequence will assure best in class patient care. This applies to visual as well as text or pictorial cues. Buttons and design must support streamlined treatment protocols as well. E.g., Did instructions use as few words as possible, in simple grammar, or simple visuals? Was it clear which buttons to push when? What about the level of information on the screen such as elapsed time and what treatment comes next?

• Consistency and coordination of all instructions and repetitions so that they reinforce each other rather than appearing to contradict. E.g., Do repetitions of a single instruction use similar enough presentation (wording or pictogram) to seem like the same instruction, or does the repetition seem like a new instruction?

• CPR functionality and ease of setup. Does the device allow a broad set of choices for Medical Directors to implement CPR protocols as they see fit. E.g., How many setup options does the device allow? How easy is it to navigate setup menus? Are setup choices clear, consistent, and grouped properly? How confident can a Medical Director be that the device will operate to protocol after it has been set up?

2. Exploration of user experience in a wide variety of realistic scenarios.

Each defibrillator was evaluated in typical training scenarios – a victim in ventricular fibrillation responded to by professional and lay first responders with the following treatment protocols:

Graphical display and care provision with a CPR protocols including three shocks followed by a period of CPR

Graphical display and care provision using a modified CPR protocol:

o CPR before initial shock o CPR between shocks o Removal of pulse checks

ECG display and care provision with a CPR protocols including three shocks followed by a period of CPR

ECG display and care provision using a modified CPR protocol:

o CPR before initial shock o CPR between shocks o Removal of pulse checks

Throughout all scenarios and circumstances, the defibrillators were evaluated for ease of use, understanding of the step-by-step experience, and minimizing distractions from patient care in treatment settings ranging from a workplace/office to outdoor events where prompts might be difficult to see or hear. Specifically, the step-by-step experience was evaluated with the above criteria as applied primarily to professional first responders’ demographics and psychographics, including their knowledge, attitudes, and cognitive strengths and limitations.

3. Summary evaluation of the user experience for each defibrillator.

Based on the identified strengths and weaknesses of each defibrillator, a summary evaluation was derived for each device.

CONCLUSION The LIFEPAK 1000 was found superior to all competitive devices in overall intuitiveness and ease of use, two key ingredients to usability. The LIFEPAK 1000’s superiority derives primarily from clarity of graphical display and intuitiveness of primary interaction area, providing well-targeted and effective cognitive support while avoiding user overload. The LIFEPAK 1000 does so without some of the weaknesses observed in other AEDs that can create high cognitive load by burdening users’ thinking and ultimately interfering with accurate and timely performance. Examples of weaknesses in competitive devices include excess visual or audio stimulation that do not directly affect patient care and tactile/affordance issues with buttons.

The LIFEPAK 1000 received consistently high usability ratings in all categories evaluated. Using the LIFEPAK 1000, caregivers get clear and concise information to move them successfully through the treatment episode and focus on the patient. Human Factors International (HFI) is the world’s largest software usability company. www.humanfactors.com