Defibrillator: Clear!

Defibrillator clear

So, this is your first day at your internship rotation in the Emergency Department. You see some movement in the resuscitation room, and someone shouts: CODE!

Then, you approach the team, excited to learn and help with cardiopulmonary resuscitation (CPR). The attending physician looks at you and asks: Do you know how to use the defibrillator?

What would your answer be?

Knowing the main functions of the defibrillator is essential but not enough; you need to get used to the model in your hospital to be able to help safely with an emergency.

Defibrillators are devices used to apply electrical energy manually or automatically. Their use is indicated for electrical cardioversion, defibrillation or as a transcutaneous pacemaker.

Later that day, another patient presents with unstable atrial fibrillation (AFib).

The attending suggests cardioverting the patient. Do you know how to prepare the defibrillator?

Defibrillation versus cardioversion

Both defibrillation and cardioversion are techniques in which an electrical current is applied to the patient, through a defibrillator, to reverse a cardiac arrhythmia.


Defibrillation is a non-synchronized electrical discharge applied to the chest, which aims to depolarize all myocardial muscle fibres, thus literally restarting the heart, allowing the sinoatrial node to resume the generation and control of the heart rhythm, and reversing the severe arrhythmias. It is indicated for pulseless ventricular tachycardia and ventricular fibrillation during CPR.

Electrical Cardioversion

Electrical cardioversion is the application of shock in a synchronized way to ensure the electric discharge is released in the R wave, that is, in the refractory period because accidental delivery of the shock during the vulnerable period, that is, the T wave, can trigger VF. It is reserved for severe arrhythmias in unstable patients with a pulse. It can usually be an elective procedure.

Special Situations

Digital Intoxication

Digital intoxication can present with any type of tachyarrhythmia or bradyarrhythmia. Cardioversion in this situation is a relative contraindication, as digital makes the heart sensitive to electrical stimulation. Before considering cardioversion, correct all electrolyte imbalances, otherwise, the cardioversion can degenerate the rhythm to a VF.

Pacemaker / Implantable cardioverter-defibrillator (ICD)

Cardioversion can be performed, but with care. The inadequate technique can damage the generator, the conductive system, or the heart muscle, leading to dysfunction of the device. The blades must be positioned at least 12 cm away from the generator, preferably in the anteroposterior position. The lowest possible electrical charge must be used.


Cardioversion can be used safely during pregnancy. The fetal beat should be monitored throughout the procedure.

Things To Consider

Keep your devices tested!

Working in the ED is not easy. This is the place where organization and preparation should be routine. Constant checking of materials and operation of the equipment must be the rule because the smallest detail can cause a difference in saving a life.

During adversity, it is necessary to remain calm, trying to not affect the reasoning and disposition of the team. It is an arduous job, it takes practice and a lot of effort. Errors can only be corrected after they are recognized and must have the right time to be exposed. It happens.

There is no time for despair, yelling and stress when it comes to CPR.

No conductive gel, what can we do?

The main guidelines regarding the use of the conductive gel used in the defibrillator paddles are:

  • Using the proper gel for this purpose is essential. The gel is an electrically conductive material that decreases the resistance to the flow of electric current between the paddle and the chest wall. The absence of conductive material can lead to the production of an arc that causes burns in the patient and the risk of explosion if there is an oxygen source very close, among others.
  • Avoid the use of gauze soaked in saline solution, as the excess serum can cause burns on the patient’s skin, but it is a reasonable option, in an emergency
  • Do not use the ultrasound gel
  • The preference is to use adhesive paddles that already come with their own conductive gel (but this is rare in Brazil).

Location recommended by Advanced Cardiac Life Support (ACLS)


One paddle is placed on the right side of the sternum, right below the clavicle and the other laterally where the cardiac appendix would be in the anterior or medial axillary line (V5-V6).

Adhesive paddles can also be placed in an anteroposterior position: The anterior one is placed in the cardiac appendage or precordial region, and the posterior one is placed on the back in the right or left infrascapular region.

During the shock, the provider must ensure that no one is in contact with the patient. A force of approximately 8k must be used to increase the contact of the paddles with the chest. Do not allow a continuous flow of oxygen over the patient’s chest to avoid accidents with sparks.


  • Electric arc (when electricity travels through the air between the electrodes and can cause explosive noises, burns and impair current delivery)
  • Electrical injuries in spectators
  • Risk of explosion if there is a continuous flow of oxygen during the shock
  • Burning of the skin by repeated shocks
  • Myocardial injury and post-defibrillation arrhythmias and myocardial stunning
  • Skeletal muscle injury
  • Fracture of thoracic vertebrae

References and Further Reading

  1. Sunde, K., Jacobs, I., Deakin, C. D., Hazinski, M. F., Kerber, R. E., Koster, R. W., Morrison, L. J., Nolan, J. P., Sayre, M. R., & Defibrillation Chapter Collaborators (2010). Part 6: Defibrillation: 2010 international consensus on cardiopulmonary resuscitation and emergency cardiovascular care science with treatment recommendations. Resuscitation81 Suppl 1, e71–e85.
  2. Panchal, A. R., Bartos, J. A., Cabañas, J. G., Donnino, M. W., Drennan, I. R., Hirsch, K. G., Kudenchuk, P. J., Kurz, M. C., Lavonas, E. J., Morley, P. T., O’Neil, B. J., Peberdy, M. A., Rittenberger, J. C., Rodriguez, A. J., Sawyer, K. N., Berg, K. M., & Adult Basic and Advanced Life Support Writing Group (2020). Part 3: Adult Basic and Advanced Life Support: 2020 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care. Circulation142(16_suppl_2), S366–S468.
  3. Ionmhain, U. N. (2020). Defibrillation Basics. Life in The Fastlane. Retrieved April 26, 2020, from
  4. Paradis, N. A., Halperin, H. R., Kern, K. B., Wenzel, V., & Chamberlain, D. A. (Eds.). (2007). Cardiac arrest: the science and practice of resuscitation medicine. Cambridge University Press.
  5. Nickson, C. (2020). Defibrillation Pads and Paddles. Life in The Fastlane. Retrieved April 26, 2020, from
Cite this article as: Jule Santos, Brasil, "Defibrillator: Clear!," in International Emergency Medicine Education Project, August 9, 2021,, date accessed: June 1, 2023

Question Of The Day #23

question of the day
3. PEA

Which of the following is the most appropriate next step in management for this patient’s condition?

This patient presented to the emergency department with acute pleuritic chest pain, dyspnea, and experienced a cardiac arrest prior to a detailed physical examination. The cardiac monitor shows a narrow complex sinus rhythm morphology. In the setting of a cardiac arrest and pulselessness, this cardiac rhythm is known as pulseless electric activity (PEA). PEA includes any cardiac rhythm that is not asystole, ventricular fibrillation, or pulseless ventricular tachycardia. The ACLS algorithm divides the management of patients with pulseless ventricular tachycardia (pVT) or ventricular fibrillation (VF) and patients with pulseless electric activity (PEA) or asystole. Assuming adequate staff and medical resources are present, patients with all of these rhythms receive high-quality CPR, IV epinephrine, and airway management. Patients with pVT or VF receive electrical cardioversion, while patients with PEA or asystole do not receive electrical cardioversion. Patients with PEA or asystole generally have a poorer prognosis than those with pVT or VF. Out of hospital cardiac arrests that present to the emergency department with PEA or asystole on initial rhythm have a survival rate of under 3%. The etiology of PEA in cardiac arrest includes a wide variety of causes. A traditional approach to remembering the reversible causes of PEA are the “Hs & Ts”. The list of the “Hs & Ts” along with their individual treatments are listed in the table below.

PEA treatments

Sodium bicarbonate (Choice A) would be the correct choice for a patient whose PEA arrest was caused by severe acidosis. This can occur in severe lactic acidosis (i.e. sepsis), diabetic ketoacidosis, certain toxic ingestions (i.e. iron, salicylates, tricyclic antidepressants), as well as other causes. Calcium gluconate (Choice B) would be the correct choice for a patient whose PEA arrest was caused by hyperkalemia. This can occur in renal failure, in the setting of certain medications, rhabdomyolysis (muscle tissue breakdown), and other causes. Blood products (Choice D) would be the correct choice for a patient whose PEA arrest was due to severe hemorrhage, such as gastrointestinal bleeding or in the setting of traumatic injuries. This patient has symptoms and risk factors for pulmonary embolism, including pleuritic chest pain, dyspnea, and a cancer history. These details make pulmonary embolism the most likely cause of PEA arrest in this scenario. The best treatment for this diagnosis would be thrombolysis (Choice C).


Cite this article as: Joseph Ciano, USA, "Question Of The Day #23," in International Emergency Medicine Education Project, December 4, 2020,, date accessed: June 1, 2023

Question Of The Day #22

question of the day
1. VFib

Which of the following is the most appropriate next step in management for this patient’s condition?

This patient presents to the Emergency Department after a cardiac arrest with an unknown medical history. Important components of Basic Life Support (BLS) include early initiation of high-quality CPR at a rate of 100-120 compressions/minute, compressing the chest to a depth of 5 cm (5 inches), providing 2 rescue breaths after every 30 compressions (30:2 ratio), avoiding interruptions to CPR, and allowing for adequate chest recoil after each compression. In the Advanced Cardiovascular Life Support (ACLS) algorithm, intravenous epinephrine is administered every 3-5 minutes and a “pulse check” is performed after every 2 minutes of CPR. The patient’s cardiac rhythm, along with the clinical history, helps decide if the patient should receive additional medications or receive unsynchronized cardioversion (defibrillation, or “electrical shock. The ACLS algorithm divides management in patients with pulseless ventricular tachycardia (pVT) or ventricular fibrillation (VF) and patients with pulseless electric activity (PEA) or asystole.

The cardiac rhythm seen during the pulse check for this patient is ventricular fibrillation. The ACLS algorithm advises unsynchronized cardioversion at 150-200 Joules for patients with pVT or VF. Continuing chest compressions (Choice A) with minimal interruptions is a crucial component of BLS, however, this patient’s cardiac rhythm is shockable. Defibrillation (Choice B) takes precedence over CPR in this scenario. Amiodarone (Choice C) is an antiarrhythmic agent that is recommended in patients with pVT, in addition to unsynchronized cardioversion. This patient has VF, not pVT. Sodium bicarbonate (Choice D) is an alkaline medication that is helpful in cardiac arrests caused by severe acidosis or certain toxins (i.e. salicylates or tricyclic antidepressants). The next best step in this patient scenario would be defibrillation for the patient’s VF (Choice B).


Cite this article as: Joseph Ciano, USA, "Question Of The Day #22," in International Emergency Medicine Education Project, November 27, 2020,, date accessed: June 1, 2023