What are the proper steps for operating an automated external defibrillator (AED) on an adult with suspected cardiac arrest?

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Last updated: June 8, 2026 • View editorial policy

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Proper Steps for Operating an AED

Turn on the AED, apply the electrode pads to the bare chest, follow the device prompts to analyze the rhythm, ensure everyone is clear before delivering a shock if advised, and immediately resume CPR starting with chest compressions after shock delivery. 1

Step-by-Step AED Operation Algorithm

1. Power On the Device

  • Turn the AED on first—this activates the voice and visual prompts that will guide you through the entire process 1, 2
  • Modern AEDs are designed to be intuitive and will provide step-by-step instructions

2. Prepare the Chest and Apply Electrode Pads

  • Expose the chest completely and ensure the skin is dry
  • Remove any chest hair if possible to reduce transthoracic impedance and ensure good pad contact 3
  • Place pads directly on bare skin—a critical error is placing pads over clothing, which occurred in up to 50% of cases in untrained users 4
  • Follow the diagram on the pads for correct placement (typically one pad on the upper right chest, one on the lower left side)
  • Avoid placing pads over breast tissue 3
  • Press pads firmly to ensure complete adhesion

3. Allow Rhythm Analysis

  • Ensure no one is touching the patient during analysis
  • The AED will automatically analyze the heart rhythm
  • Do not interrupt this process

4. Deliver Shock if Advised

  • If a shockable rhythm is detected (VF/pulseless VT), the AED will charge and advise shock delivery
  • Loudly announce "Clear!" and visually confirm no one is touching the patient 1
  • Press the shock button when prompted
  • Give 1 shock only 1, 2

5. Immediately Resume CPR

  • Do not check for a pulse or rhythm after the shock
  • Resume chest compressions immediately—this is critical for survival 1, 2
  • Perform CPR for exactly 2 minutes (30 compressions to 2 breaths if trained, or continuous compressions if untrained) 1
  • The AED will prompt you when to stop for the next rhythm check

6. Repeat the Cycle

  • After 2 minutes, the AED will prompt another rhythm analysis
  • Follow the same sequence: analyze → shock if advised → immediate CPR
  • Continue until advanced providers arrive or the victim shows signs of life 1

Critical Timing Considerations

Use the AED as soon as it arrives—do not delay to complete a CPR cycle 1, 2. When an AED is immediately available on-site, start CPR and use the AED as quickly as possible. Every minute of delay in defibrillation decreases survival by 7-10% without CPR, or 3-4% with CPR 2.

Common Pitfalls to Avoid

  • Never place pads over clothing—this was the most common error in untrained users 4
  • Do not delay CPR to set up the AED—one person should perform compressions while another prepares the device 1
  • Do not check for pulse or rhythm immediately after shock—this wastes critical time; resume compressions immediately 1, 2
  • Minimize interruptions in chest compressions—frequent or prolonged interruptions significantly reduce survival 2
  • Do not touch the patient during rhythm analysis or shock delivery 1

Integration with CPR

The AED is not a replacement for CPR but works synergistically with it. CPR should begin immediately upon recognizing cardiac arrest, before the AED arrives 1. The sequence is: recognize arrest → activate emergency response → start CPR → apply AED as soon as available → follow AED prompts while continuing high-quality CPR 1, 2.

High-quality CPR means compressions at least 2 inches deep, rate of 100-120/min, allowing complete chest recoil, and minimizing interruptions 1.

References

3
Research

How to use an automated external defibrillator following out-of-hospital cardiac arrest.

Nursing standard (Royal College of Nursing (Great Britain) : 1987), 2017

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Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.