Pauses in chest compressions are known to be detrimental to survival in cardiac arrest, so much so that the 2010 American Heart Association (AHA) emphasize high-quality compressions while minimizing interruptions. There have been some studies that now advocate for continuous chest compressions during a defibrillation shock. There have been substantial changes to external defibrillation technology including:
Biphasic shocks with real-time impedance monitoring to reduce peak voltages
Paddles being replaced by adhesive pre-gelled electrodes
Enhancement in ECG filtering permitting rhythm monitoring during chest compressions.
So the mantra of "hard and fast" may be true when it comes to CPR, but the real question now becomes, should we be continuing CPR during defibrillation?