â€œPush Hard, Push Fastâ€
We all know the mantra. Itâ€™s catchy.
Compressions not deep enough?Â Push hard.
Not fast enough?Â Push fast.
Great. Exceptâ€¦ One thing many of us have learned as professional rescuers is that the bigger issue is not pushing too slow, but pushing too fast.
â€œButâ€¦push FAST!â€ I mean, faster has to be better right?
How many times have we witnessed CPR administered in a way that seems like a race to set the world record for fastest compression rate? How many times have we seen someone compress at an appropriate rate only to be chided to go faster?
While we know that compressing at a rate <100/min is too slow to provide effective CPR, how fast should we actually compress?
At some point, can fast be too fast?
I did not find a lot of definitive research on this. What I did find indicates that the optimal rate of compressions are betweenÂ 100-120 per minute. If the rate rises aboveÂ 125, ROSC declines sharply (1). The classic law of diminishing returns kicks in, and bad things start to happen to decrease the chances of a successful outcome:
- Increased rescuer fatigue
- Compressions become more shallow and less effective
- Full recoil of the chest is diminished
Clearly, these negative factors work against effective resuscitation and best practices. The only problem is that compression rates often reach the 140-180 range during resuscitative efforts.
I conducted an experiment a couple of years back utilizing an instrumented manikin. Iâ€™ll admit that the sample size was small, but I believe the results to be representative of the average rescuer. Compressors were told to provide guideline CPR, and results were recorded. No metronome was utilized. The average rate delivered over the first two minutes was 140. As a BCLS/ACLS instructor, I have witnessed â€œtoo fastâ€ compressions often, and I have heard of similar experiences elsewhere. Why does this happen? A few reasons are apparent to me:
- Adrenaline surge
- Poor temporal awareness
- Gap in knowledge
The adrenaline surge is easy to understand. It makes us want to go fast, and leap tall buildings in a single bound. Some of the fastest compression rates will be at the beginning of the code, just when we need effective compressions most. While it happens to all of us, not everyone has the same ability to control it, and prevent it from hindering our performance.
Poor temporal awareness
Related to the adrenaline surge, when under stress our ability to perceive time is distorted. Against our best efforts, time seems to slow down or speed up to the point where we can not accurately sense time lapses. It becomes difficult to effectively sense the difference between a compression rate of 110 and 140. This requires training, and even better the use of a metronome. This is akin to the problem of inadvertently over-ventilating patients at a too-fast rate.
Think about it: At a compression rate of 120/minute, at the edge of the effective zone, we are providing 2 compressions per second. At a rate of 150 compressions/minute, outside of the effective zone, we are giving 2.5 compressions per second. I donâ€™t think itâ€™s easy to perceive the difference between 2 and 2.5 compressions per second under non-stressful conditions, do you? How do you think we do under stress? Without an effective mechanism to control this, we can easily slip outside the effective range.
Many providers still do not realize that â€œpush hard, push fastâ€ has an upper limit, and that giving compressions at a rate > 125 can be detrimental to outcomes. â€œThe faster the betterâ€ approach is still pervasive out in the field. More of an educational emphasis needs to be placed on the idea that faster isnâ€™t always better.
Compression rates matter. While I would like to see more research in this area, for what we know now, we need to have a mechanism in place to prevent â€œover-compressingâ€. A metronome or similar device would seem to fit the bill. Simple, affordable, but still very under-utilized.
(1) Study determines optimal chest compression rate (Idris, M.D.)
Image credit: foxnews.com