What is the recommended initial shock energy (in joules) for biphasic defibrillation during adult CPR?

JIPMER Nursing Officer-2024

Medical & Surgical Nursing

Easy

Appeared in: JIPMER Nursing Officer-2024

Explanation

The recommended initial energy dose for adult biphasic defibrillation is 150 Joules (J).
Biphasic technology allows for successful defibrillation at lower energy levels compared to older monophasic devices, which reduces the risk of myocardial injury.
Guidelines specify an initial shock of 150 J, with subsequent shocks delivered at 150-200 J if ventricular fibrillation or pulseless ventricular tachycardia persists.
This strategy is based on the principle of delivering sufficient energy to terminate the arrhythmia while minimizing potential harm.

Option A: While some specific biphasic devices may have a protocol starting at 120 J, 150 J is the more commonly cited and recommended initial energy level in major resuscitation guidelines.
Option C: 200 J is typically recommended for subsequent shocks if the initial shock fails, or it may be the maximum energy setting for some biphasic devices. It is not the standard initial dose.
Option D: 360 J is the standard energy dose for a monophasic defibrillator. Using this energy level with a biphasic device is incorrect and delivers excessive energy.

Visual 1: Diagram: A visual comparing the biphasic waveform (current flows, reverses, then stops) versus the monophasic waveform (current flows in one direction). This helps explain why biphasic is more efficient.
Visual 2: Infographic: Correct defibrillator pad placement for an adult (anterolateral position) with labels for the upper right chest and lower left chest/apex.
Visual 3: Flowchart: A simplified Adult Cardiac Arrest Algorithm showing the sequence: CPR -> Rhythm Check -> Shock (if VF/pVT) -> Immediate CPR -> Repeat.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Initial energy dose for adult biphasic defibrillation during CPR as background academic context rather than a clinical decision trigger.
Patient safety is paramount during defibrillation. The nurse's primary safety action is ensuring the area is 'clear' before delivering a shock to prevent injury to the resuscitation team.
Effective CPR is as critical as defibrillation. The nurse must ensure high-quality chest compressions are resumed immediately after the shock to maintain perfusion to the brain and heart.
Nurses must be familiar with the equipment in their clinical setting. Knowing whether the available defibrillator is monophasic or biphasic is essential for selecting the correct energy level.

How to Approach the Question

First, identify the key terms in the question: 'initial shock', 'biphasic defibrillation', and 'adult'.
Recall the fundamental difference between biphasic and monophasic defibrillators. Biphasic uses lower energy.
Immediately eliminate 360 J, as this is the well-known energy level for monophasic devices.
You are left with 120 J, 150 J, and 200 J. These are all within the biphasic range. The question asks for the initial recommended energy.
Recall from ACLS guidelines that the standard starting dose is often cited as 120-200 J. However, many protocols and textbooks specify 150 J as the typical first shock.
Select 150 J as the most accurate and commonly recommended initial dose, recognizing that 200 J is a subsequent dose.

Concept Tested & Keywords

Concept Tested: Initial energy dose for adult biphasic defibrillation during CPR.
Stem keywords: biphasic defibrillation, adult CPR, initial shock energy, joules
Lead-in keywords: What is

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