During an unwitnessed collapse, how long of CPR should be performed before attaching the AED?

• A. One minute of CPR prior to attaching the AED
• B. Two minutes of CPR prior to attaching the AED
• C. Four minutes of CPR prior to attaching the AED
• D. No CPR before attaching the AED

Answer: (B)

When a collapse is unwitnessed, keeping blood flowing to the brain and heart through chest compressions is the priority before defibrillation. About two minutes of continuous CPR helps rebuild coronary and cerebral perfusion so that when the AED arrives and analyzes the rhythm, defibrillation is more likely to be effective. This window balances giving the heart some perfusion support with not delaying the defibrillation process too long. The AED should be attached as soon as it’s available, and CPR continues with any necessary pauses for analysis and shock delivery, but the idea behind two minutes of CPR first is to maximize perfusion before shocking.