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
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.
Pregnancy
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)
Antero-lateral
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.
Complications
- 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
- 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. Resuscitation, 81 Suppl 1, e71–e85. https://doi.org/10.1016/j.resuscitation.2010.08.025
- 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. Circulation, 142(16_suppl_2), S366–S468. https://doi.org/10.1161/CIR.0000000000000916
- Ionmhain, U. N. (2020). Defibrillation Basics. Life in The Fastlane. Retrieved April 26, 2020, from https://litfl.com/defibrillation-basics/
- 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.
- Nickson, C. (2020). Defibrillation Pads and Paddles. Life in The Fastlane. Retrieved April 26, 2020, from https://litfl.com/defibrillation-pads-and-paddles/