A man is admitted to the telemetry unit for evaluation of complaints of chest pain. Eight hours after admission, the patient goes into ventricular fibrillation. The physician defibrillates the patient. The nurse understands that the purpose of defibrillation is to?

1. A

   Increase cardiac contractility and cardiac output

2. B

   Cause asystole so the normal pacemaker

3. C

   Reduce cardiac ischemia and acidosis

4. D

   Provide energy for depleted myocardial cells

Appeared in: GMCH Chandigarh - 2019

Explanation

• The primary purpose of defibrillation is to stop the chaotic electrical activity of ventricular fibrillation (VF).
• It achieves this by delivering a strong electrical current that depolarizes a large portion of the heart muscle all at once.
• This mass depolarization causes a brief moment of asystole (cardiac standstill).
• This 'electrical reset' provides an opportunity for the heart's natural pacemaker, the sinoatrial (SA) node, to resume its normal function and generate an organized, perfusing rhythm.

Why Other Options Were Wrong

• Option A: Defibrillation does not directly increase the force of heart contractions. Its function is purely electrical, not mechanical.
• Option C: Cardiac ischemia and acidosis are consequences of cardiac arrest, not the direct target of defibrillation. The shock does not reverse these metabolic states.
• Option D: This is a common misconception. The electrical shock is not a form of metabolic energy for the heart cells. It is an electrical current that forces a change in the cells' electrical state (depolarization).

Related Visual

Clinical Relevance

• Nursing practice connection: Prioritize focused assessment, early escalation, and real-time monitoring when managing Purpose of Defibrillation in Ventricular Fibrillation in acute care settings.
• Early defibrillation is a critical link in the chain of survival for out-of-hospital and in-hospital cardiac arrest. For every minute that a person in VF goes without defibrillation, the chance of survival decreases by about 10%.
• Nurses must be able to rapidly recognize VF on a monitor, initiate high-quality CPR, and safely operate a defibrillator. This includes ensuring the safety of the resuscitation team by calling 'All clear!' before delivering a shock.
• Post-resuscitation care is crucial. After a successful defibrillation, the nurse must monitor for return of spontaneous circulation (ROSC), assess hemodynamic stability, manage the airway, and identify and treat the underlying cause of the arrest.

How to Approach the Question

• First, identify the clinical event in the question: the patient is in ventricular fibrillation (VF).
• Next, identify the intervention: defibrillation.
• The question asks for the purpose of this intervention. This requires recalling the fundamental mechanism of action for defibrillation.
• Evaluate each option against this mechanism. Option A (contractility) is a mechanical effect, not electrical. Option C (ischemia/acidosis) describes consequences of arrest, not the target of the shock. Option D (cell energy) is a common misconception.
• Option B describes the core principle: stopping the chaos (VF) to create a pause (asystole) that allows the normal pacemaker to restart. This directly matches the known mechanism of defibrillation.

Concept Tested & Keywords

• Concept Tested: Purpose of Defibrillation in Ventricular Fibrillation
• Stem keywords: ventricular fibrillation, defibrillates, purpose of defibrillation
• Lead-in keywords: purpose of
• Clinical cues: patient goes into ventricular fibrillation

Question ID

QJi-dLtlG5X3hy5UrbDX1G

Copy ID

Reference Book

E6 Medicine Davidson Principles Practice 24e p. 502-504

E6 Ghai Essential Pediatrics(pp 26-904 of 913) p. 767-769