United Press International (UPI) is reporting that according to a study by the University of Michigan Health System, the chance of surviving an out-of-hospital cardiac arrest remains unchanged over the last 30 years.

The analysis of 79 studies involving 142,740 patients, published in Circulation: Cardiovascular Quality and Outcomes, found 23.8 percent of the patients survived to hospital admission and 7.6 percent lived to be discharged from the hospital.

While half of cardiac arrests were witnessed by a bystander, only 32 percent received bystander cardiopulmonary resuscitation.

"Increasing bystander CPR rates, increasing the awareness and use of devices to shock the heart and keeping paramedics on scene until they restore a person's pulse needs to occur if we are ever going to change our dismal survival rate," Dr. Comilla Sasson, the study's lead author, said in a statement.

I find this study to be interesting because it shows that only about half of cardiac arrests are witnessed. Unwitnessed cardiac arrests have a very poor prognosis, which is not surprising when you consider that this is the most time sensitive of all emergencies.

Knowing how many cardiac arrests are witnessed by a bystander is important when estimating how many "savable" cardiac arrest patients a given EMS system interacts with in a given year.

According to the best data I could find, the incidence of out-of-hospital cardiac arrest in the general population is approximately 1/10 of 1% (or 1 out of 1000).

That means that each year, a community of 50,000 people can expect about 50 out-of-hospital cardiac arrests.



If half of them are witnessed, the number is down to 25.



It's reasonable to assume that not all of those are VF/VT arrests. This isn't evidence based, but let's say that 20 of them are primary cardiac VF/VT arrests.



According to the Utstein template, the number of these patients that walk out of the hospital is a community's save rate. If the save rate is 10% then a community of 50,000 can expect 2 patients to survive to hospital discharge each year.



It's worth mentioning that most communities don't measure their outcomes at all, so this is just speculation.

Let us assume for a moment that this same community started to save 35% of its cardiac arrest patients. Instead of saving 2 patients each year they would save 7 or an additional 5.



Five may not seem like a lot of patients, but in 30 years that's 150 people, or enough to fill up a Boeing 737 (or Airbus A320).



Do you remember when Captain Sullenberger saved 150 passengers (plus the crew) on US Airways Flight 1549?



He was recognized as a hero, and justifiably so! Here's New York City Mayor Michael Bloomberg showing off the "key to the city" that was specially made for Captain Sullenberger.



Stengthening a community's "chain of survival" is a lot less dramatic than saving 150 people in a single afternoon, but we need to remember that these are real people, and they are loved just as much by their wives, husbands, daughters, son, mothers, and fathers.

So what are we waiting for?

See also:

Essential Features of Designating Out-of-Hospital Cardiac Arrest as a Reportable Event

Cardiac Arrest Registry to Enhance Survival (CARES)