• Understanding of the anatomy and physiology of the cardiovascular system, principles of cardiac conduction, basic dysrhythmia interpretation, and electrical safety is needed.

• Basic and advanced cardiac life support (ACLS) knowledge and skills are necessary.

• Clinical and technical competence in the use of the defibrillator is needed.

• Ventricular fibrillation and pulseless ventricular tachycardia are lethal dysrhythmias. Early emergent defibrillation is the treatment of choice to restore normal electrical activity and coordinated contractile activity within the heart.2,8

• The electrical current delivered with defibrillation depolarizes the myocardium, terminating all electrical activity and allowing the heart’s normal pacemaker to resume electrical activity within the heart.2,8 Defibrillator paddles or pads placed over the patient’s chest wall surface in the anterior-apex or anterior-posterior position maximize the current flow through the myocardium.²

• Defibrillators deliver energy or current in waveform patterns. Delivered energy levels may differ between different defibrillators and waveforms. Various types of monophasic waveforms are used in older defibrillators. Biphasic waveforms have been designed more recently and are used currently in implantable cardioverter defibrillators (ICDs), automatic external defibrillators, and most manual defibrillators.

• Monophasic waveforms deliver energy in one direction. The energy travels through the heart from one paddle or pad to the other.²

• Biphasic waveforms deliver energy in two directions. The energy travels through the heart in a positive direction and then reverses itself and flows back through the heart in a negative direction.¹⁰ Researchers have found that biphasic waveform technology is able to decrease the amount of current needed to terminate the dysrhythmia (less than or equal to 200 J), decreasing the amount of potential damage to the myocardium.^7,13 Researchers also found that 115- to 130-J biphasic waveform shocks achieved the same first shock success rate as 200-J monophasic waveform shocks and these shocks also produced less ST-segment change than the monophasic shocks.^1,7 Investigators from in-hospital and out-of-hospital studies concluded that repetitive lower energy biphasic waveform shocks had equal or higher success rates for eradicating ventricular fibrillation than defibrillators that increase the current with each shock (200 J, 300 J, 360 J).^1,2 More research is needed to determine a specific recommendation for the optimal energy level for biphasic waveform defibrillation.^1,2,7 Biphasic energy recommendations are device specific. Biphasic defibrillators use one of two waveforms. Devices with a biphasic truncated exponential waveform are effective with 150 to 200 J of energy, whereas devices with a rectilinear waveform are effective with 120 J of energy. If the operator is unaware of the effective biphasic dose, the American Heart Association (AHA) recommends delivery of 200 J for the first shock, followed by equal or higher doses for subsequent shocks.^2,8 This energy level was chosen because it falls within the reported ranges of effective doses for first and subsequent biphasic shocks.^2,8

• Biphasic defibrillators measure and compensate for transthoracic impedance before the delivery of the shock, which allows the defibrillator to deliver the actual amount of energy selected by the rescuer.1,2

• A wearable cardioverter defibrillator (WCD) has recently been developed for patients at high risk for sudden cardiac death. Patient populations may include those who do not meet the current guidelines for an ICD implantation but who are at risk; those who are unable to receive an ICD because of infection; and those patients at high risk who are awaiting cardiac transplant. This wearable defibrillator has the ability to detect and treat life-threatening tachydysrhythmias without bystander support and allows the patient to ambulate freely. The initial defibrillators were programmed to provide a monophasic waveform for shocks. Preliminary results have shown that WCD is a safe and effective method to terminate life-threatening dysrhythmias in this high-risk patient population. The next generation devices use biphasic shocks, which are also proving to be successful in terminating ventricular fibrillation.¹¹

• Defibrillator with electrocardiogram (ECG) oscilloscope/recorder

• ECG cable

• Conductive gel, paste, or prepackaged gelled conduction pads or self-adhesive defibrillation pads connected directly to the defibrillator

• Bag-valve device with mask and oxygen delivery

• Flow meter for oxygen administration, oxygen source

• Emergency suction and intubation equipment

• Blood pressure monitoring equipment

• Pulse oximeter

• Intravenous infusion pumps

• Cardiac board

• Emergency medications