Innovation and Change: How CPR and AEDs Became a Part of Our Lives
Death, due to sudden cardiac arrest, or SCA, is a big problem. Typically related to heart disease, sudden cardiac arrest affects nearly 300,000 Americans each year. As its name suggests, these events occur quickly, and in most cases, without warning. They can occur at any time and in any place.
Most importantly, if one occurs in front of you, you are the only solution. There are only a few minutes between the time sudden cardiac arrest occurs and when treatment becomes useless. A bystander has the best, and maybe the only chance to help.
So how would you deal with a sudden cardiac arrest? Simple. You push. Push 911 on your cell phone. Push on the center of the chest. Push hard. Push fast. Push the shock button on the automated external defibrillator. Then, push again on the chest…
Some detail will help.
Your heart is a hollow muscle that squeezes down due to a repeating electrical impulse that goes through its tissue. The contraction forces the blood that fills the heart forward into the body. Moving blood picks up the oxygen you breathe in the lungs and continues on to the rest of the body.
This is how we get oxygen, which is required by the body to live, to individual body cells. The tissue most sensitive to a lack of oxygen is brain tissue. It can only survive a few minutes without oxygen. When there is a significant loss of brain tissue, a person cannot survive.
“Sudden” cardiac arrest occurs when the regular electrical impulses in the heart abruptly go haywire and turn the normal squeezing contraction of the heart into a quivering disorder. Technically this quivering is called ventricular fibrillation, and, when it occurs, the flow of blood from the heart stops. This in turn causes the affected person to suddenly lose consciousness and collapse.
The best way to approach this situation is to think about the underlying problem in two parts, mechanical and electrical. The immediate danger is the lack of oxygen to the brain because the regular blood-moving contractions of the heart have been lost. The way to manage that part of the problem is to somehow find another way to physically move blood through the body. This is accomplished by performing cardiopulmonary resuscitation, or CPR, using a combination of external chest compressions and rescue breaths.
Unfortunately, CPR can only deal with the mechanical part of the problem. CPR is not intended to solve the electrical chaos of ventricular fibrillation. It is also limited in its ability to maintain enough blood flow for an extended period of time. Without addressing the electrical part of the problem, CPR will be unable to effectively treat the problem on its own.
Defibrillation is the use of electricity to “shock” a quivering heart’s electrical activity back into a regular pattern that hopefully can stimulate normal contractions and return spontaneous blood flow. A defibrillator is a device that is designed to deliver defibrillation.
Without CPR, there is generally not enough time for a defibrillator to work. Without a defibrillator, CPR has a very low chance of success.
So let’s see if we can sum up the basic concept so far…
There are only a few minutes to react when a sudden cardiac arrest occurs before the ability to survive is lost. Immediate CPR can return some blood flow and delay the loss of brain tissue, but rapid defibrillation is required to solve the underlying cause of the problem. Seems simple enough…but we have to get better at it.
Historically, surviving sudden cardiac arrest has been nearly impossible. The current overall national survival rate for SCA in the United States is still pretty low, somewhere around 10-15%. Over the past century, a number of key events have occurred to bring us to our current approach to treatment. While there has been some improvement for society at large, remarkable improvements have mostly been seen only in local areas that focus on resuscitation fundamentals. Some local AED programs have survival rates as high as 40-50%!
We can understand these fundamental concepts better when we learn how they came about. Let’s highlight the key events in the history of resuscitation and see how a collection of strange treatments, random moments, and dedicated individuals have shaped how we deal with sudden cardiac arrest today.