The earlier the defibrillation occurs, the higher the survival rate. When a fatal arrhythmia is present, CPR can provide a small amount of blood flow to the heart and the brain, but it cannot directly restore an organized rhythm. The likelihood of restoring a perfusing rhythm is optimized with immediate CPR and defibrillation. The purpose of defibrillation is to disrupt a chaotic rhythm and allow the heart’s normal pacemakers to resume effective electrical activity.
The appropriate energy dose is determined by the design of the defibrillator—monophasic or biphasic. If you are using a monophasic defibrillator, give a single 360 J shock. Use the same energy dose on subsequent shocks. Biphasic defibrillators use a variety of waveforms and have been shown to be more effective for terminating a fatal arrhythmia. When using biphasic defibrillators, providers should use the manufacturer’s recommended energy dose. Many biphasic defibrillator manufacturers display the effective energy dose range on the face of the device. If the first shock does not terminate the arrhythmia, it may be reasonable to escalate the energy delivered if the defibrillator allows it.
To minimize interruptions in chest compressions during CPR, continue CPR while the defibrillator is charging. Be sure to clear the individual by ensuring that oxygen is removed and no one is touching the individual prior to delivering the shock. Immediately after the shock, resume CPR, beginning with chest compressions. Give CPR for two minutes (approximately five cycles). A cycle consists of 30 compressions followed by two breaths for an individual without an advanced airway. Those individuals with an advanced airway device in place can be ventilated at a rate of one breath every 5 to 6 seconds (or 10 to 12 breaths per minute).