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Difficulty: HardCardiovascular System

A 59-year-old woman suddenly collapses while walking in the hospital corridor. A rapid response team arrives immediately. The patient is completely unresponsive, apneic, and has no palpable carotid pulse. The team brings a crash cart with a manual defibrillator, and cardiac monitoring reveals coarse ventricular fibrillation. Arrange the following resuscitative interventions in the correct chronological sequence according to current Advanced Cardiac Life Support (ACLS) guidelines for this rhythm.

  1. 1Initiate high-quality chest compressions
  2. 2Deliver the initial unsynchronized biphasic shock
  3. 3Administer 1 mg of intravenous epinephrine
  4. 4Deliver the third unsynchronized biphasic shock
  5. 5Administer 300 mg of intravenous amiodarone

Answer

The correct chronological sequence is: 1) Initiate high-quality chest compressions, 2) Deliver the initial unsynchronized biphasic shock, 3) Administer 1 mg of intravenous epinephrine, 4) Deliver the third unsynchronized biphasic shock, 5) Administer 300 mg of intravenous amiodarone.
The Advanced Cardiac Life Support (ACLS) guidelines for a shockable rhythm (ventricular fibrillation or pulseless ventricular tachycardia) dictate a highly specific, cyclical sequence of events. First, high-quality CPR must be initiated instantly upon recognition of cardiac arrest. Second, as soon as the rhythm is identified as shockable, the initial defibrillation (shock 1) is delivered, followed immediately by 2 minutes of CPR. If the rhythm remains shockable, a second shock is delivered, followed by another 2 minutes of CPR. It is during this specific CPR cycle (after the 2nd shock) that the first dose of epinephrine (1 mg) is administered. If the rhythm is still shockable at the next check, a third shock is delivered. During the CPR cycle following this third shock, antiarrhythmic therapy (such as 300 mg of amiodarone) is administered to treat refractory ventricular fibrillation. This rigid sequence optimizes myocardial perfusion while systematically escalating interventions.

Step-by-Step Solution

1
Identify the cardiac arrest rhythm and establish the foundational initial action.
High-quality chest compressions are initiated immediately.
CPR maintains vital organ perfusion and is the very first step in the chain of survival while the defibrillator is being prepared.
2
Determine the priority intervention for a shockable rhythm.
The initial unsynchronized biphasic shock is delivered.
For ventricular fibrillation, early defibrillation is the most definitive treatment and must be performed as soon as the device is attached and charged.
3
Sequence the administration of vasopressors in the algorithm.
Intravenous epinephrine is administered.
ACLS guidelines state that epinephrine is given every 3-5 minutes, starting during the CPR cycle that follows the second shock, if the rhythm remains shockable.
4
Sequence the progression to refractory interventions.
The third unsynchronized biphasic shock is delivered.
After the CPR cycle containing epinephrine, if the rhythm check still shows ventricular fibrillation, a third shock is mandated.
5
Sequence the administration of antiarrhythmics.
Intravenous amiodarone is administered.
Antiarrhythmic therapy (amiodarone or lidocaine) is reserved for truly refractory ventricular fibrillation and is given during the CPR cycle following the third shock.

Key Concept

Advanced Cardiac Life Support (ACLS) Pulseless Arrest Algorithm for Shockable Rhythms
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Topics

Cardiovascular System

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