Designing Lifesaving Defibrillators


Physio-Control, Inc. makes lifesaving medical devices: simple defibrillators for use by the public (AEDs) and advanced defibrillator / monitors for use by first responders, nurses, and doctors. In my three years at Physio-Control, I focused on two key areas of design within the company: designing an internal tool for engineers (a drawing library) and designing accessories (batteries, bags, electrodes) for our flagship advanced-use defibrillator.


Throughout my time at the company, I took as many opportunities to study Emergency Medicine users as possible. I rode in ambulances with EMTs and paramedics, shadowed doctors in ERs, and participated in usability testing and rescusitation simulations. All of this informed my understanding of the pressure our users faced in their use of our equipment. While working on defibrillator accessories, I gathered input from various teams to create product requirements that engineers, marketing, human factors, and project management could all agree on.


The engineering library I designed is still in use and keeping mistakes to a minimum. The accessories I defined are still in product development, but when released they will be a significant improvement over their predecessors.

user research & evaluation

I studied my emergency medicine users in several ways, including:

  • Teaching high school students to operate Automatic External Defibrillators (AEDs)
  • Observing paramedics and emergency room doctors during their shifts
  • Contributing to focus groups of flight nurses and paramedics interacting with prototype products
  • Participating in usability testing for our AED products and several days of emergency simulations on our company campus, playing various roles in the ambulance/hospital setting

Of my several user evaluations, one was particularly stressful (solo resuscitation of a child). That experience gave me a strong sense of how hard it is for a person to internalize that it is a design, not him/her, which is being evaluated.

Julie performing CPR on a dummy for a user simulation

Experience map artwork

I created this vector graphic by request for the Human Factors team to use in a new experience map. The stages of the Emergency Medicine process shown here were used to communicate internally to engineers and designers about the feelings of users at each point in their workflow. I subsequently modified the graphic for confidentiality and clarity.

graphic depicting paramedics in their work: getting a call, arriving on scene, rescusitation, transportation of patient, and handoff to hospital

led UI - prototype

When designing the requirements for the defibrillator battery, I ran into a potentially confusing user interface. To help shed light on the issue, I designed several battery LED animations. I put them on a mobile device and put it in the hands of stakeholders (engineers, managers, marketing execs, etc) to demonstrate the confusion. The animations were also used in a survey to gather data from users to inform the decision of whether to change the interface. The specific LED behavior shown here is just an example, to protect confidentiality.

example animation of battery led behavior
battery of previously released defibrillator, shown for context

service design

My first project at Physio-Control was to redesign the engineering drawing library. I interviewed and did extensive observations of the users of the current system to discover the largest sources of inefficiency and error. To solve these issues, I implemented a new database with graphical interface (image on right) that allows multiple users and limits manual entry. With the new system, the department runs more efficiently and errors have been significantly reduced. I created the experience map below to communicate the experience of engineers and PCB designers when trying to add a new part to a circuit board. The previous system required 22 steps, lots of manual data entry, and several avenues to do the same work multiple times. The new system I designed only has 15 steps, automates as much data entry as possible, and adds an approval system so part information is checked only once.

screenshots of the new part library I implemented
diagram showing the steps needed to place a part on a circuit board, before and after my system redesign: 22 before, 15 after