In its latest campaign, the American Heart Association is advising would be rescuers to "Push hard and fast" when performing CPR. The 2010 CPR Guidelines changed previous advice on chest compressions from "about 100 per minute" to "at least 100 per minute." Rescuers are told to simply make sure they get full depth and recoil on the chest for each compression.
Chest Compressions Have Gotten Faster
When the American Heart Associatioin originally released the 100/minute standard in 2005, it wasn't supposed to result in actually delivering 100 chest compressions per minute. At the time, the 30:2 ratio meant that after every 18 or so seconds of chest compressions (the length of time it takes to do 30 compressions at a rate of 100/minute) rescuers would stop for two breaths, a pause that shouldn't last more than 10 seconds. A proficient rescuer could easily get two cycles of 30:2 done every minute, leading to a total of about 60 compressions per minute with ventilations.
Hands-Only CPR wasn't an accepted alternative yet. In an unprecedented move, the association allowed Hands-Only to become an alternative standard in 2008, midway through the typical update cycle. In 2010, there was an even bigger push to allow Hands-Only and some emergency medical services systems in the US are foregoing ventilations in professional resuscitations. Rescuers have been encouraged to do more compressions and do them faster than ever before.
Chest Compression Speed Limit?
No pause for ventilation means more time pumping on the chest. We've gone from about 60 compressions every minute to at least 100. Now that we're doing so much compressing, there is a growing body of evidence that chest compressions have a maximum speed as well as a minimum. In 2012 a study of 3,098 cardiac arrest patients showed that speed matters in chest compressions. Researchers found a decreasing return on investment when rescuers pumped on the chest more than 125 times per minute.
In this study, researchers were using a device that keeps track of the chest compressions and tells us exactly how fast the rescuers were pushing. More importantly, their measuring stick for success versus failure was whether or not the patient's heart started taking over again (known in the EMS biz as return of spontaneous circulation or "Hot diggity, we got pulses back!").
There is an important caveat here: the speed of the compressions didn't have much effect on survival to hospital discharge, another -- many would say more important -- measuring stick. We still don't know exactly where the chest compression sweet spot is.
What's it All Mean?
For most of you, CPR will be a once in a lifetime endeavor. You're likely to be more concerned with hand placement or how long it's taking the ambulance to get there. This is one of those studies that has a small group who should care about the findings. For everyone else, faster is generally better than slower.
For that group, here's the takeaway: When you have that rescuer who's amped and wanting to pound away on the chest -- you know the type who considers even chest compressions a competition -- put a hand on his shoulder and have him ease up on the throttle a bit. It makes sense not to beat the chest 130+ times per minute when it lowers the chance of a positive result and increases rescuer fatigue.
Idris AH, et al. "Relationship between chest compression rates and outcomes from cardiac arrest." Circulation. 2012 Jun 19;125(24):3004-12. Epub 2012 May 23. PubMed PMID: 22623717