A woman who asked us to call her Strawberry taught me cardiopulmonary resuscitation (CPR) for the first time, more than thirty years ago. I was getting my Girl Scout badge in babysitting, and it was a requirement. The class involved an overview of the “ABC’s” and half-hearted compressions on our friends. We did a craft afterward.

A few years later, I took my second CPR class in my high school natatorium. Determined to be a lifeguard, I sat on the wooden bleachers in the dank pool area for several evenings that winter, listening to an instructor from the Red Cross and highlighting my manual with a yellow marker. The class had two “Annies” that we took turns blowing into. Afterward, you could wipe the mouth with alcohol if you wanted to, but the teacher cautioned that in a real-life scenario, you “wouldn’t have that luxury.” During that class, I practiced the “head-tilt, chin-lift” technique and chest compressions. I spent the following summer lifeguarding with a few rescues, but thankfully, zero occasions to perform CPR.

In college, I took another first aid and CPR class mainly because it fulfilled a physical education credit. I can’t remember much about that class other than that it involved us all practicing the Heimlich maneuver on one another, and I was always nauseous afterward. I was relieved we didn’t have to do mouth-to-mouth breathing on each other, but I still wasn’t sure if I could effectively use these skills in the real world.

Then came medical school, internship, and residency with certifications in basic life support, advanced cardiac life support, and pediatric advanced life support. Emergency medicine physicians and nurses taught us how to run codes. I memorized algorithms and doses for epinephrine and atropine. I learned how to “bag” with an Ambu bag. My compressions were criticized by people who knew what they were doing.

During night float my intern year, I finally performed chest compressions in real life on a living patient. She was an elderly woman who came in pulseless and unresponsive via squad in the wee hours of the night. The resident pushed me to the head of her gurney and told me what to do. As soon as I began compressions, I felt the patient’s brittle sternum crack under my palms. I hesitated, and then the resident reassured me it was common. My own heart raced as I tried to resuscitate this patient.

After this night, many more codes occurred that year. They usually involved a steely physician or nurse with years of experience loudly and calmly stating orders while everyone else on the team efficiently bustled around, followed the commands, and desperately tried everything possible to save a life.

In the early 2000s, my program director taught us how to use a portable defibrillator. Everyone realized that these machines were game-changers. After applying the two sticky pads to your patient and pressing a button on the machine, this idiot-proof device could analyze a heart rhythm and quickly determine if a shock was recommended. If used right away, research proved that AEDs decreased mortality and improved survival exponentially.

Last week, I took BLS for probably the fifteenth time, and it is easy to appreciate numerous changes in the last three decades. Now, we have cell phones to call 911 at the sight of an emergency, and there is widespread access to automated portable AEDs in public places such as airports, offices, and sports arenas. The course training materials have become more sophisticated with manikins that have built-in LED lights for feedback, and training AEDs are smaller than an iPad. Furthermore, throughout the years, the American Heart Association has also adjusted many details in the algorithms. For example, the rate of chest compressions increased to 100-120/minute in 2015. Throughout the years, there was also a greater emphasis put on “compression-only” CPR for laypeople, and ABC changed to CAB.

Despite these variations in guidelines, technology, and maneuvers, CPR still exists today as the only way to save someone suffering from cardiac arrest. Therefore, even three decades later, it still rings true that if someone isn’t breathing and doesn’t have a pulse, pushing hard and fast on their chest can save their life.

Sarah C. Smith is a family physician.