We know that for every minute after a person’s heart stops from cardiac arrest there is a 10 percent drop in the survival rate, but did you know that AEDs used in conjunction with CPR feedback devices may further reduce survival rates, because CPR must be stopped to place the CPR feedback pads? The Heart and Stroke Foundation of Canada has recommended that AEDs are put in place to ensure that a life-saving shock can be administered within three minutes of a person’s heart stopping. When this 3 minute drop-to-shock time is achieved, greater than 70% of patients survive. Prior to the introduction of AEDs in public and work places, the survival rate was less than 5%.
CPR Feedback Devices at Odds with Heart and Stroke Foundation CPR Recommendations
The Heart and Stroke recommendation is a result of numerous studies which concluded that defibrillation performed soon after the onset of cardiac arrest is the most important determinant of survival.
The first step in helping to save a cardiac arrest patient is to activate Emergency Services by calling 9-1-1 or the local emergency number, so professional rescuers are dispatched as quickly as possible.
The second step is to start CPR and send for the nearest AED. The Heart and Stroke Foundation advocates hands-only CPR as a key life-saving measure. Early CPR after a cardiac arrest ensures that an adequate supply of blood and oxygen are provided to the body’s key organs – particularly the brain and heart.
Once the AED arrives at the scene easy to place “electrode pads” can be applied while CPR continues without interruption. But AED devices with CPR feedback usually require that CPR be stopped while placing the pads and CPR feedback device, due to the complexity of the pads and the fact that they require access to the centre of the chest where CPR compressions are applied.
Uninterrupted CPR Improves Survival Rates
The International Standard for CPR emphasizes providing uninterrupted hands-only CPR as a means of further improving survival rate. So stopping CPR for any other reason than allowing the AED to analyze the heart rhythm should be avoided.
In addition to the interruption in CPR, researchers at the University of Illinois studied the use of common AEDs and found that rescuers took almost a minute longer to place CPR feedback pads as opposed to regular AED pads. The obvious result is an additional minute of delay in administering the life-saving shock with an additional drop in the chance of survival by at least 10 percent.
While there is emphasis on providing high quality CPR to victims of sudden cardiac arrest, particularly by professional responders, there is a strong case to be made to try to achieve the Heart and Stroke objective of a three minute drop-to-shock time. Keeping the process to rescue a cardiac arrest victim as simple as possible could result the best possible survival rate. This is especially important for lay responders who rarely would have to respond to a cardiac arrest emergency.
The Bottom Line
So, purchasers of AEDs should not be lured into thinking an AED with a CPR feedback device is going to result in improved survivability. In fact, more complicated AEDs can result in time lost in delivering that all important shock, with a decreased chance of survival.
Based on the Heart and Stroke Foundation’s objective and the findings of the University of Illinois study, we recommend using the “Keep it Simple” approach – Call 9-1-1, start hands-only CPR as quickly as possible and have an AED nearby (hopefully within 90 seconds of the patient), and deliver that shock within three minutes if the AED decides it is needed.
- Valenzuela, Terrence D., M.D., M.P.H. et al, Outcomes of Rapid Defibrillation by Security Officers after Cardiac Arrest in Casinos, N Engl J Med 2000; 343:1206-1209
- Robertson, Rose Marie, M.D., Sudden Death from Cardiac Arrest – Improving the Odds, N Engl J Med 2000; 343:1259-1260
- Polikaitis, Audrius, PhD, The Usability of Five Automated External Defibrillators by Minimally Trained Bystanders, University of Illinois Medical Center, Chicago, Illinois
- American Heart Association, Guidelines 2015 CPR & ECC, Dallas, Texas