United Press International (UPI) reports that according to a study by the University of Michigan Health System, the chance of surviving an out-of-hospital cardiac arrest has remained 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 cardiac arrest 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 percent (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 of “savable” victims is down to 25.
It’s reasonable to assume that not all of those 25 are ventricular fibrillation/ventricular tachycardia (VF/VT) arrests. This isn’t evidence based, but let’s say that 20 of the 25 are primary cardiac VF/VT arrests. (An important distinction, because automated external defibrillators (AEDs) are designed to treat sudden cardiac arrest victims whose hearts are experiencing VF/VT.)
According to the Utstein template (an international standard for calculating cardiac arrest survival rates) the number of VF/VT patients who walk out of the hospital determines a community’s save rate. If the save rate is 10 percent, then in a community of 50,000, we can expect 2 VF/VT 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 percent of its cardiac arrest patients. Instead of saving 2 patients each year they would be saving 7 — or an additional 5 people a year.
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.
Strengthening 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, sons, mothers, and fathers.
So what are you waiting for? Get defibrillators for your community today.
See also:
Essential Features of Designating Out-of-Hospital Cardiac Arrest as a Reportable Event
Cardiac Arrest Registry to Enhance Survival (CARES)
December 24th, 2009 at 7:07 am
Tom, Fantastic post and analysis.
It begs the question about the enormous amount of money that is spent on ambulances with paramedics, fire trucks with BLS providers, and all of the equipment to just save 1 in 50,000 per year.
Increasing bystander CPR is a low cost intervention relative to the other costs in the chain of survival.
December 29th, 2009 at 3:38 pm
Greg –
Thanks for the comment. You’re right! It does beg some questions. The problem is that most communities don’t measure their response to cardiac arrest, so they have no idea how many cardiac arrests they respond to, how many receive bystander CPR, how often AEDs are used, how often patients experience return of spontaneous circulation in the field, how many survive to hospital admission, and most importantly, how many survive to hospital survival with a high level of neurological functioning.
The first step is for a community to “know its numbers.” If they’re only saving 1 in 50,000 (an estimated 5% Utstein survival) then it’s time for some soul searching! We know that communities that don’t measure probably aren’t doing well. It’s just not acceptable. Our citizens deserve better! Hopefully with continuous chest compressions, the rate of bystander CPR will increase significantly! That’s important because it “buys time” for the defibrillator to arrive.
It’s almost impossible for a dispatchable resource to arrive and apply a shock within 4 minutes of collapse.
Tom
December 29th, 2009 at 3:46 pm
I recently met a prominent medical director who questions the method used to collect the data. If I can get something concrete, we’ll post it as a reply to this excellent post.
Thank you, Tom + Greg.
December 29th, 2009 at 3:52 pm
Joe –
I’ve heard others criticize the Ustein template for only including witnessed arrests with shockable rhythms, but it seems to me it’s the best way to make apples-to-apples comparisons from one community to another.
Unwitnessed asystolic arrests, for example, offer virtually no chance of survival. Is that fair barometer of an EMS system’s performance? The Utstein template seems to ask the question, “How many of the most saveable victims of cardiac arrest are you saving?”
Sounds like a good question to me!
For what it’s worth, we now track all of our cardiac arrest patients (with the assistance of the CARES registry).
Tom
P.S. How do I fix typos in my comments?