CPR is one of the fundamental skills that EMS provides, yet most of us probably don't know the quality of the CPR that our system provides. Yes, we may be able to say that we've trained to the latest guidelines and have complete buy-in from our practitioners but can we quantify the "boast" that we provide "great" CPR? In one study of 176 adult patients with out-of-hospital cardiac arrest in Sweden, England and Norway, researchers found ALS CPR provision didn't comply with international guidelines.(1) Chest compressions weren't given 48% of the time without spontaneous circulation, and only a mean of 28% of chest compressions were of adequate depth.
Others have reported similar findings for prehospital and hospital resuscitations. In one study, researchers evaluated CPR with auditory and visual prompts performed on non-randomized victims of cardiac arrest attended by ALS crews.(2) Failure to comply led to an escalation of the prompt, for example from a tone to a voice message. The overall conclusion was that quality of CPR improved when automated feedback was used and that when feedback priority was changed, a parallel increase in quality was noted. There was no improvement in survival to discharge from ventricular fibrillation (V-fib) arrest in the historic group compared to the prompted group, but logistic regression showed an increased short-term survival with increased chest compression.
The authors also noted the unexpected outcome of significant hands off-time despite prompts. This was a different outcome than had been seen in BLS manikin training where compliance was much better, and the authors explained that providers overrode the prompts to accomplish other tasks, presumably IV access and airway placement. Acceptance of the technology was high among the users. It is a reasonable question to ask whether this attention to detail really matters and the answer seems to be "yes."
A study used monitors to measure rate and depth of compressions as well as hands-off time to determine the effect of the quality of CPR on outcome from V-fib arrest of patients.(3) The author concluded that each 5 mm increase in compression depth and each five-second decrease in pre-shock pause leads to an approximate twofold increase in the likelihood of shock success.
Evidence is building that, on the one hand we may not know as much as we need to about how CPR is being delivered in the field, and on the other that the quality of CPR is very important. Tools exist to help us monitor the important aspects of CPR and allow us to provide this feedback to our providers. At a minimum we need to continue to follow this very promising technology and its potential impact on our care.
- Wik L, Steen PA, Bircher NG. "Quality of bystander cardiopulmonary resuscitation influences outcome after prehospital cardiac arrest." Resuscitation. 28(3):195-203, 1994.
- Kramer-Johansen J, Mykelbust J, Wik L et al: "Quality of out-of-hospital cardiopulmonary resuscitation with real time automated feedback: A prospective interventional study." Resuscitation. 71(3):283–292, 2006.
- Edelson, DP, Abella BS, Kramer-Johansen J, et al: "Effects of compression depth and pre-shock pauses predict defibrillation failure during cardiac arrest."