DEFIBRILLATION TECHNIQUES FOR ADULTS: WHAT YOU NEED TO KNOW

Defibrillation is a critical, life-saving intervention used to terminate certain life-threatening cardiac arrhythmias by delivering a controlled electric shock to the heart. This procedure is primarily indicated for patients experiencing ventricular fibrillation (VF) or pulseless ventricular tachycardia (pVT), both of which are common causes of sudden cardiac arrest. These arrhythmias prevent the heart from pumping blood effectively, leading to immediate circulatory collapse and, if untreated, death. The goal of defibrillation is to depolarize a critical mass of myocardial cells simultaneously, allowing the heart’s natural pacemaker (the SA node) to re-establish a perfusing rhythm. Given its immediate impact on patient survival, understanding the correct procedure for defibrillation in adults is paramount for both healthcare professionals and trained lay rescuers.

Underlying Principles and Urgency

The effectiveness of defibrillation is highly time-dependent. For every minute defibrillation is delayed, the chance of survival decreases by approximately 7-10%. Therefore, immediate recognition of cardiac arrest, prompt initiation of cardiopulmonary resuscitation (CPR), and rapid deployment of a defibrillator are crucial for a positive outcome. CPR helps to maintain some blood flow to the brain and heart, temporarily extending the window for successful defibrillation.

Safety First: Prerequisites and Considerations

Before attempting defibrillation, several critical safety and preparatory steps must be observed:

1. Scene Safety: Ensure the environment is safe for both the rescuer and the patient. Check for hazards like water, live electrical wires, or combustible materials.
2. Early Recognition and Call for Help: Confirm the patient is unresponsive and not breathing normally (or only gasping). Immediately activate the emergency medical services (EMS) system (e.g., call 911 or your local emergency number) and request an AED.
3. Initiate High-Quality CPR: If cardiac arrest is confirmed and no defibrillator is immediately available, begin high-quality chest compressions with minimal interruptions. Continue CPR until the AED arrives and is ready for use.
4. Understanding Defibrillator Types:
   • Automated External Defibrillators (AEDs): These devices are designed for use by both trained lay rescuers and healthcare professionals. They analyze the heart rhythm and deliver a shock automatically (or advise the user to press a button) if a shockable rhythm is detected. AEDs are equipped with voice prompts and visual cues to guide the user.
   • Manual Defibrillators: Used by advanced healthcare providers, these devices require the operator to interpret the electrocardiogram (ECG) rhythm, select the appropriate energy level (in joules), and deliver the shock manually.

This guide will focus on AED operation, as it is the most common and accessible method for immediate defibrillation.

Step-by-Step Guide for Adult Defibrillation (Using an AED)

The following steps outline the procedure for using an AED on an adult in cardiac arrest:

Step 1: Arrive, Assess, and Initiate CPR

• Confirm Unresponsiveness and Absent/Abnormal Breathing: Gently tap the patient and shout, “Are you okay?” Look, listen, and feel for normal breathing for no more than 10 seconds.
• Call for Emergency Medical Services (EMS): If the patient is unresponsive and not breathing normally, immediately activate your emergency response system. If alone, put your phone on speaker and begin CPR. If others are present, one person should call EMS while another prepares for CPR and retrieves the AED.
• Begin High-Quality CPR: If an AED is not immediately available, begin chest compressions (30 compressions to 2 breaths) at a rate of 100-120 compressions per minute, to a depth of at least 2 inches (5 cm), allowing for complete chest recoil. Continue CPR until the AED is ready for use.

Step 2: Retrieve and Prepare the AED

• Power On the AED: Once the AED arrives, immediately place it next to the patient’s head or chest, and power it on. Follow the AED’s voice prompts and visual instructions explicitly.
• Expose the Patient’s Chest: Quickly and fully expose the patient’s chest. Clothing, jewelry, and any patches must be removed to ensure proper pad adhesion. Speed is critical; do not waste time removing excessive clothing if it can be quickly cut or torn.

Step 3: Apply Defibrillator Pads

• Ensure Dry Skin: The patient’s chest must be dry. If the chest is wet (e.g., from sweat, rain, or water), quickly wipe it dry.
• Manage Excess Hair: Excessive chest hair can prevent the pads from adhering properly. If present, quickly shave the area where the pads will be placed using the razor often found in AED kits. If no razor is available, a temporary alternative is to apply one set of pads firmly, then quickly pull them off to remove hair, and then apply a new set of pads.
• Apply Pads Correctly: Open the electrode pad package. Note that adult pads are typically larger than pediatric pads. Apply the pads directly to the bare skin of the patient’s chest in the standard anterolateral position:
  • One pad on the upper right side of the chest, just below the collarbone, to the right of the sternum.
  • The other pad on the lower left side of the chest, along the midaxillary line, with the top edge of the pad several inches below the armpit.
  • Ensure the pads do not touch each other or any metal objects (like pacemakers or medication patches – see special considerations below).
• Connect Pads to AED: Plug the electrode pad connector cable into the AED unit (if not already pre-connected).

Step 4: Analyze Heart Rhythm

• “Stand Clear!” / “Don’t Touch the Patient!”: Once the pads are correctly applied and connected, the AED will begin analyzing the patient’s heart rhythm. It is absolutely critical that NO ONE TOUCHES THE PATIENT during this analysis phase. Verbally announce, “Everybody clear!” and visually confirm that no one (including yourself) is in contact with the patient or the bed/stretcher.
• AED Analysis: The AED will usually take several seconds to analyze the rhythm. It will then advise whether a shock is necessary or not.

Step 5: Deliver Shock (If Advised)

• “Shock Advised”: If the AED determines a shockable rhythm (VF or pVT), it will announce “Shock advised” and begin to charge.
• “Clear!” Procedure (Redundant Safety Check): Even though you cleared the patient for analysis, it is imperative to clear again before delivering the shock.
  • Verbal Warning: Loudly and clearly announce, “I’m going to deliver a shock! Everybody clear!”
  • Visual Confirmation: Visually scan the patient from head to toe, ensuring no one is touching the patient, the bed, or any equipment connected to them. Ensure your own hands are clear.
  • Press Shock Button: Once absolutely sure everyone is clear, press the flashing “Shock” button. The AED will deliver the electrical shock. The patient’s body may visibly jerk or twitch.
• Immediate Resumption of CPR: Immediately after the shock is delivered, WITHOUT DELAY, resume chest compressions. Do not check for a pulse or rhythm at this point. Continue CPR for approximately 2 minutes (or 5 cycles of 30:2).

Step 6: Continue CPR and Re-analyze

• Continue High-Quality CPR: After 2 minutes of CPR (or as prompted by the AED), the AED will typically prompt for another rhythm analysis.
• Repeat Analysis and Shock (If Advised): If the AED advises another shock, repeat Step 5: “Clear!” and deliver the shock, then immediately resume CPR.
• No Shock Advised: If the AED advises “No shock advised” (e.g., the rhythm has changed to asystole or a perfusing rhythm), continue CPR and monitor for signs of circulation. If the patient regains consciousness and normal breathing, place them in the recovery position and monitor closely until EMS arrives.
• Continue until EMS Takes Over: Continue following the AED prompts, performing CPR and delivering shocks as advised, until EMS personnel arrive and take over care, or the patient shows signs of life.

Special Considerations During Defibrillation

• Hairy Chest: As mentioned, excessive hair can prevent pad adhesion. Shaving with a razor (if available in the AED kit) is ideal. If not, quickly apply and tear off one set of pads to “wax” the area, then apply a new set.
• Wet Environment: Water conducts electricity. Ensure the patient and the area around them are as dry as possible to prevent current diversion and potential injury to rescuers. Move the patient if necessary.
• Implanted Devices: Pacemakers or Implantable Cardioverter-Defibrillators (ICDs) create a small bulge under the skin, usually in the upper chest. Avoid placing AED pads directly over these devices; place the pads at least an inch away.
• Medication Patches: Remove any medication patches (e.g., nitroglycerin, nicotine) from the chest area before applying pads, as they can block electrical current and potentially cause skin burns.
• Children: Use pediatric pads and/or reduced energy settings if available, following AED instructions. If adult pads are the only option, ensure they do not touch each other.

Brief Note on Manual Defibrillation (Advanced Providers)

For healthcare professionals trained in Advanced Cardiovascular Life Support (ACLS), manual defibrillation involves:

1. Rhythm Interpretation: Accurately identifying VF or pVT on a cardiac monitor.
2. Energy Selection: Choosing the appropriate energy level (e.g., 120-200 Joules for biphasic, 360 Joules for monophasic, as per guidelines) based on the device and patient.
3. Pad/Paddle Placement: Similar to AED pads, ensuring good contact for paddles with conductive gel.
4. Charging and Clearing: Manually charging the device and ensuring a thorough “Clear!” before delivering the shock.
5. Immediate CPR: Resuming CPR immediately after the shock.

Manual defibrillation requires a deeper understanding of cardiac rhythms and advanced clinical judgment.

Conclusion

Defibrillation is a cornerstone of resuscitation for ventricular fibrillation and pulseless ventricular tachycardia. While the concept of delivering an electric shock may seem daunting, modern AEDs are designed to guide rescuers through the process safely and effectively. The critical elements for success are early recognition of cardiac arrest, prompt activation of EMS, immediate and high-quality CPR, rapid deployment and correct use of a defibrillator, and continuous chest compressions with minimal interruptions. By understanding and practicing these steps, individuals can significantly improve the chances of survival for someone experiencing sudden cardiac arrest. Continuous education and adherence to current resuscitation guidelines are vital to optimizing outcomes in these time-sensitive medical emergencies.

References

1. American Heart Association (AHA). (2020). AHA Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care. Circulation, 142(16_suppl_2), S337-S440. [Specific sections on adult basic and advanced life support, including defibrillation].
2. European Resuscitation Council (ERC). (2021). ERC Guidelines for Resuscitation 2021. Resuscitation, 161, 1-456. [Specific sections on adult basic and advanced life support, including defibrillation].
3. Wik, L., et al. (2009). Defibrillation: current and future perspectives. Critical Care Medicine, 37(1_suppl), S188-S191.
4. Link, M. S., et al. (2015). Part 7: Adult Advanced Cardiovascular Life Support: 2015 American Heart Association Guidelines Update for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care. Circulation, 132(18_suppl_2), S444-S464.