Every room in our Seattle, Washington design and manufacturing facility has a sign with our promise to customers. “We design and produce every device as if the life of someone we love depends on it”. That promise is deeply heartfelt by every employee. A major way of meeting this commitment is by designing our AEDs to be as easy as possible to use by inexperienced responders under considerable stress. The defibrillator must pull the lay-responder through, not get in their way. Here are some of the design elements that result in an AED that was proven unsurpassed in ease of use in several published studies.1,2,3
Extensive user testing. During the design process, a HeartStart device’s human factors are tested and refined over and over again, using ordinary people put in simulated cardiac arrest situations. They are videotaped interacting with the device, and studied carefully. Every point at which a user is unsure or confused is considered a design flaw for the device’s user interface. This uncovers a host of potential pitfalls and dead ends in device use that signal a potential failed rescue, and are designed out of the device before bringing it to market.
The right voice. The voice you hear giving instructions from our defibrillators is carefully chosen to have just the right blend of attributes:
- Calming. Responders have plenty of adrenalin flowing by virtue of the situation they are in. What they need is a calming presence so they can think clearly and build confidence in their ability to respond coolly and competently.
- Building a rapport with the rescuer—Our designers prefer a voice with whom the responder will naturally build an affinity. If the responder “likes and respects” the person giving the voice instructions, the device may seem more human. The responder and device are more likely to form a positive and effective team.
- Commanding. People have difficulty making decisions under considerable stress. So the voice we choose should naturally inspire the responder to put their trust in the device, listen carefully, and faithfully do exactly as instructed.
- Culturally sensitive. Voice talent for our various language devices are chosen locally by teams in-country so as to capture the above attributes in a way that is faithful to the culture in which the device will be used. This is intended to further build a rapport with the stressed user.
Detailed instructions, yet not wordy. Voice instructions should be sufficiently detailed to take an untrained user through a rescue. This is a foreign and frightening experience for the responder. They may have no training, or training on a different device. So voice instructions must make sure nothing is left to chance in guiding a responder to perform a procedure they seldom practice. Yet sentences must be short, and there should be no unnecessary words that do not contribute to understanding. It is our experience that long sentences potentially cause confusion and frustration for a stressed responder. They may require more concentration than the responder is able to provide.
Instructions paced to your actions. Voice instructions are designed to move along at the user’s pace. They should not outpace the user, leaving them behind, anxious, and lost. And they should not slow the responder down, wasting valuable time, leaving them frustrated, and tempting them to “go it alone”, acting before being instructed, and possibly acting incorrectly. HeartStart defibrillators are uniquely able to know where the user is in the response and closely pace instructions accordingly. The HeartStart FRx and OnSite (HS1) have a unique feature our engineers call “pad fiddle”. The pads can sense when they are first being touched and manipulated. This helps the AED know more precisely than other AEDs where the user is in their response. The device will then adjust instructions accordingly to provide instructions appropriate to the user’s progress. This makes for a more human interaction between user and device, like there is a coach watching them and guiding them step by step. It is designed to help make the responder more confident and effective, and less distracted from the task at hand.
Special emphasis. If we find during user testing that a step or key point tends to sometimes be missed or glossed over by the user, we will place special attention-getting emphasis on that step when recording the final voice instructions. We find this results in better user performance.
Instructions not followed are re-phrased. When a voice instruction is not performed, the HeartStart AED recognizes it, and stays with the responder to invite them again to perform the step. But we don’t simply repeat the same instruction over and over again, like many other AE Ds. If the responder did not understand the instruction the first time, we don’t assume they will the second, third or forth time the instruction is repeated. We assume that maybe the responder does not understand what the device is asking them to do, and what is expected of them. So we express the instruction using different words that maybe the responder will better understand.
Visual instructions communicate with out overloading the senses. Most users rely on the voice instructions. However HeartStart AEDs also provide visual queues that are more graphical and less written. These graphics-based visual instructions are designed to communicate instantaneously with minimum reading and interpretation, yet not compete with the voice instructions for the user’s limited attention span. Think of them as dashboard lights on your automobile. This is also designed to improve understanding for users that may not be as fluent in the device’s language. In user tests, respondents were actually able to rely on these graphical queues to perform a rescue in the absence of voice instructions.
Reminder to call for help. We include an instruction to call emergency services, just in case the responder overlooked that critical step.
CPR Coaching. Our FRx and OnSite (HS1) device offer the inexperienced responder detailed CPR coaching to help them recall their training. It is there on demand for those who need it. Simply press the blue i-button when invited. CPR is a difficult motor skill that, once learned, is not well retained when not put to use.4 Also, responders may have received their most recent training years ago, and CPR guidelines may have been different then. CPR coaching is designed to help the stressed user remember their training and to encourage performance of CPR according to current guidelines. It includes coaching for the more complex motor actions, such as the mechanics of opening an airway or the depth and pace of chest compressions. As one Red Cross instructor put it so well, “That little blue button is the answer to all their anxieties about CPR.”
Infant/Child Key. In user testing, and in anecdotes from customers, people love the FRx Infant/Child key. It obviates the need to change pads for the rescue of a child, saving steps. By inserting the key, which is shaped to instinctively convey to a stressed responder “child!” (the key resembles a teddy bear rattle), the device is ready for a pediatric rescue. It also shows the correct pad placement for children. All subsequent voice instructions and the shock dosage are appropriate for a child.
Easy battery replacement. In the unlikely event that a device battery will need replacement mid-rescue, we design our batteries to pop out and pop in easily, in one quick action. Chances are you will not have to use this feature in a rescue, but it is reassuring that you can replace a battery smoothly and easily if needed, minimizing unnecessary frustration or distraction.
At Philips, we believe it is the little things that make the difference between a satisfying, efficient rescue and a frustrating and failed rescue. So we pay attention to the details. And we test on users. And test again until it is right.
Because an AED should pull the stressed responder through, not get in their way.
1 Andre et al, Prehospital Emergency Care 2004; 8:284-291.
2 Eames et al, Resuscitation 58 (2003); 25-30.
3 Fleischhackl et al, Resuscitation 62 (2004); 167-174.
4 American Heart Association Guidelines 2005. Circulation 2005; 112.