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Difficulty: MediumCardiovascular System

A 62-year-old man with a history of ischemic cardiomyopathy suddenly collapses while walking in the hospital corridor. A rapid response team arrives immediately. The patient is unresponsive, apneic, and has no palpable carotid pulse. High-quality chest compressions are initiated, and a defibrillator is attached. The monitor displays coarse ventricular fibrillation.

Assuming the patient remains in refractory ventricular fibrillation throughout the resuscitation, arrange the following advanced cardiac life support (ACLS) interventions in the correct chronological sequence.

  1. 1Deliver the initial unsynchronized defibrillation shock.
  2. 2Resume continuous chest compressions immediately without checking for a pulse.
  3. 3Perform a rhythm check after 2 minutes of CPR and deliver a second defibrillation shock.
  4. 4Administer 1 mg of intravenous epinephrine.
  5. 5Administer 300 mg of intravenous amiodarone.

Answer

The correct chronological sequence is: deliver the initial shock, immediately resume chest compressions, perform a rhythm check after 2 minutes of CPR and deliver a second shock, administer epinephrine, and finally administer amiodarone.
According to the Adult Cardiac Arrest Algorithm, the management of pulseless ventricular fibrillation (VF) begins with immediate high-quality CPR and rapid defibrillation. Once the defibrillator is attached and VF is recognized, the very first step is to deliver an unsynchronized shock. Crucially, immediately after the shock is delivered, chest compressions must be resumed for a full 2-minute cycle without stopping to check the rhythm or pulse. After 2 minutes, a rhythm check is performed, and if VF persists, a second shock is delivered. During the CPR cycle following the second shock, epinephrine 1 mg IV is administered. If VF continues after a third shock, an antiarrhythmic such as amiodarone (300 mg IV) is administered. This strict sequence maximizes coronary and cerebral perfusion while allowing appropriate intervals for electrical and pharmacological therapy.

Step-by-Step Solution

1
Identify the shockable rhythm and deliver the first shock.
The initial shock attempts to depolarize the myocardium and terminate the ventricular fibrillation.
Early defibrillation is the most critical intervention for survival in shockable cardiac arrest.
2
Immediately resume cardiopulmonary resuscitation (CPR) starting with chest compressions.
Blood flow to the heart and brain is temporarily restored.
Prolonged pauses in compressions severely decrease survival rates. A pulse or rhythm check should never immediately follow a shock delivery.
3
Re-evaluate the rhythm after 2 minutes of CPR and deliver a second shock.
A second defibrillation attempt is made for refractory ventricular fibrillation.
ACLS guidelines mandate a rhythm check only after complete 2-minute cycles of CPR to minimize hands-off time.
4
Administer the first dose of epinephrine.
Epinephrine 1 mg is given intravenously while CPR is ongoing.
Epinephrine is administered after the second shock (during the subsequent CPR cycle) and every 3-5 minutes thereafter to improve coronary and cerebral perfusion pressure.
5
Deliver a third shock (after another 2 minutes of CPR) followed by amiodarone.
Amiodarone 300 mg is administered intravenously.
Antiarrhythmic medications are indicated for ventricular fibrillation that persists after high-quality CPR, multiple shocks, and vasopressor administration.

Key Concept

Advanced Cardiac Life Support (ACLS) management sequence for pulseless ventricular fibrillation and pulseless ventricular tachycardia.
Estimated Time:1m 30s
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Topics

Cardiovascular System

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