# A patient with atrial fibrillation is receiving continuous cardiac monitoring. The nurse observes a sudden change to ventricular tachycardia on the monitor. The patient becomes unresponsive with no palpable pulse. What is the nurse's immediate priority action?

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## 문제

A patient with atrial fibrillation is receiving continuous cardiac monitoring. The nurse observes a sudden change to ventricular tachycardia on the monitor. The patient becomes unresponsive with no palpable pulse. What is the nurse's immediate priority action?

## 보기

1. Administer epinephrine 1 mg IV push immediately
2. Initiate immediate defibrillation with 200 joules biphasic **✔ 정답**
3. Begin chest compressions at 100-120 per minute
4. Establish advanced airway with endotracheal intubation

**정답: 2**

## 해설

In pulseless VT, immediate defibrillation is the priority as it can restore organized rhythm and circulation. Other interventions like epinephrine, compressions, or airway management are secondary after defibrillation.

## 심화 해설

Clinical Scenario Analysis

The monitor shows a sudden change from atrial fibrillation to ventricular tachycardia in a patient who is now unresponsive and pulseless. This clinical picture defines a shockable rhythm cardiac arrest. The immediate priority is to deliver the first shock as quickly as possible, as the probability of successful defibrillation declines rapidly with each passing minute.

Why Immediate Defibrillation is the Priority

In a witnessed, monitored cardiac arrest with a shockable rhythm (ventricular tachycardia or ventricular fibrillation), the underlying pathophysiology is chaotic, asynchronous electrical activity that prevents coordinated myocardial contraction. The most effective intervention is to depolarize a critical mass of the myocardium simultaneously with a direct-current shock, allowing the heart's natural pacemaker to resume control. The 2025 Korean Guidelines for Cardiopulmonary Resuscitation emphasize a structured approach to advanced life support, and the foundational step for a shockable rhythm is defibrillation. Initiating defibrillation with 200 joules biphasic is the correct, evidence-based priority action that directly treats the proximate cause of the arrest.

Analysis of Other Options Based on Guideline Principles

The guidelines establish a clear sequence of interventions that prioritizes early defibrillation over drug administration and advanced airway placement for shockable rhythms.

| Option | Rationale for Not Being the Immediate Priority |
| --- | --- |
| 1. Administer epinephrine 1 mg IV push immediately | While the guidelines recommend epinephrine as the vasopressor of choice during cardiac arrest, it is not the first intervention for a shockable rhythm. The initial priority is defibrillation. Epinephrine is administered after the first or second shock, typically every 3 to 5 minutes, to increase coronary and cerebral perfusion pressure during chest compressions. Delaying defibrillation to give a drug would be a critical error, as the rhythm's responsiveness to electrical therapy is time-sensitive [1]. |
| 3. Begin chest compressions at 100-120 per minute | High-quality chest compressions are a cornerstone of cardiac arrest management, but in a witnessed, monitored arrest with a shockable rhythm, the immediate action is defibrillation. The guidelines support a strategy where, if a defibrillator is immediately available, a shock should be delivered without a preceding period of chest compressions. Chest compressions are initiated immediately after the shock, without pausing for a rhythm check, to maintain myocardial perfusion [1]. |
| 4. Establish advanced airway with endotracheal intubation | Advanced airway management is a lower-priority intervention in the initial phase of a cardiac arrest. The guidelines focus on minimizing interruptions in chest compressions and delivering shocks. While the preferred initial route for drug administration is intravenous access, with intraosseous access as an alternative, securing an advanced airway is deferred until after the initial rhythm-specific interventions (defibrillation) and high-quality CPR are underway. The immediate goal is to restore a perfusing rhythm, not to intubate [1]. |

The core principle from the guideline update is a structured, evidence-based sequence: for a pulseless patient with a shockable rhythm, the immediate priority is to deliver a shock using a biphasic defibrillator at the manufacturer's recommended dose, typically 200 joules for the first shock. This action provides the best chance for return of spontaneous circulation [1].References (research sources)

- [1]2025 Korean Guidelines for Cardiopulmonary Resuscitation: Part 4. Adult advanced life support.GuidelineKim TY, Ahn GJ, Cha KC, Kim DH, Sohn Y, Song Y, Shim G, Kim DK, Oh Y, Wi J, Youn CS, Lee ML, Lee MJ, Lee BK, Lee BH, Lee J, Lee CH, Lee H, Jang Y, Jang YS, Jung YH, Jung WJ, Chung SP, Cho GC, Heo JS, Hwang SO. (2026) · DOI: 10.15441/ceem.26.073

## 임상 시나리오

ACLS Pulseless Arrest: Shockable RhythmImmediate Defibrillation Priority
For a witnessed, monitored cardiac arrest with a shockable rhythm (pulseless VT/VF), the single most critical intervention is immediate defibrillation. The probability of success declines 7-10% per minute without CPR and shock.

Use a biphasic defibrillator at the manufacturer's recommended dose (typically 200 J). If the dose is unknown, use the maximum available. Resume chest compressions immediately after the shock without pausing for rhythm or pulse check.

CautionDo not delay defibrillation for vascular access, advanced airway placement, or drug administration. For a pulseless patient, a monomorphic VT on the monitor is treated exactly like VF.

## 핵심 개념

- **Ventricular Tachycardia (VT)** — A rapid heart rhythm originating from the ventricles, which can be pulseless and lead to cardiac arrest.
- **Defibrillation** — Delivery of a therapeutic dose of electrical energy to the heart to terminate a life-threatening arrhythmia.
- **Shockable Rhythm** — A cardiac arrest rhythm (Ventricular Fibrillation or pulseless Ventricular Tachycardia) that can be treated with defibrillation.
- **Biphasic Defibrillator** — A type of defibrillator that delivers current in two directions, typically requiring lower energy doses (e.g., 200J) than older monophasic devices.
- **Advanced Cardiac Life Support (ACLS)** — A set of clinical interventions for the urgent treatment of cardiac arrest, stroke, and other life-threatening cardiovascular emergencies.

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