How many cycles of CPR to be given followed by one shock, if the victim has a shockable rhythm, while providing advanced life support in cardiac arrest?

Appeared in: RRB Nsg Superintendent -29 April 2025 (Shift-1st)

Explanation

According to Advanced Cardiovascular Life Support (ACLS) guidelines, 2 minutes of high-quality CPR should be performed immediately after a defibrillation attempt.
A single cycle of CPR consists of 30 chest compressions and 2 rescue breaths (30:2 ratio).
With a compression rate of 100-120 per minute, the 2-minute interval accommodates approximately 5 cycles of CPR.
This practice maximizes coronary and cerebral perfusion, increasing the likelihood of return of spontaneous circulation (ROSC).

Option B: 2 cycles of CPR would last less than one minute, which is an insufficient duration of chest compressions between shocks and deviates from standard ACLS protocol.
Option C: 3 cycles of CPR would last approximately 1 minute and 15 seconds, which is shorter than the recommended 2-minute interval needed for effective perfusion.
Option D: 4 cycles of CPR is closer to the target but still falls short of the full 2-minute duration recommended by guidelines for maximizing resuscitation success.

Visual 1: Flowchart - An infographic of the ACLS algorithm for a shockable rhythm (VF/pVT), clearly showing the loop of 'Shock -> 2 min CPR -> Rhythm Check'.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain CPR Cycles in Advanced Cardiac Life Support (ACLS) as background academic context rather than a clinical decision trigger.
A nurse's primary role in a cardiac arrest is to provide high-quality CPR with minimal interruptions. Knowing the 2-minute/5-cycle standard is fundamental to being an effective member of the code team.
Minimizing the 'hands-off' time (pauses in compressions) is one of the most critical factors for survival. The 2-minute interval is a structured way to ensure this.
What if? If the rhythm was non-shockable (Asystole/PEA), the protocol changes. The focus would be on continuous high-quality CPR for 2-minute cycles and administering epinephrine every 3-5 minutes, with no defibrillation shocks delivered.

How to Approach the Question

First, identify the question as a factual recall question about a specific medical protocol (Advanced Life Support).
Note the key clinical context: 'shockable rhythm' and 'advanced life support'. This points directly to the ACLS algorithm.
Recall the standard ACLS sequence for a shockable rhythm: a shock is followed by a period of immediate, uninterrupted CPR.
Remember the duration of this CPR interval, which is 2 minutes.
Convert the 2-minute duration into CPR cycles. Knowing a cycle is 30:2 and takes about 24 seconds, calculate that 120 seconds / 24 seconds = 5 cycles.
Select the option that matches this calculation.

Concept Tested & Keywords

Concept Tested: CPR Cycles in Advanced Cardiac Life Support (ACLS)
Stem keywords: CPR, cardiac arrest, advanced life support, shockable rhythm, cycles
Lead-in keywords: How many
Negative lead-in flag: false

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Practise the full RRB Nsg Superintendent -29 April 2025 (Shift-1st)

Attempt every question from this paper in a timed mock, then review the full solution for each one.