Question
A 60-year-old male collapses in a monitored cardiac unit and is undergoing advanced life support. After about 5 minutes of chest compressions, the rhythm shows ventricular fibrillation and a defibrillation shock is delivered. Immediately after the shock, the cardiac monitor now shows an organised rhythm pattern. What should be done next?
a) Pause and check for a pulse, and if present begin post-arrest management
b) Continue chest compressions for 2 minutes before reassessing rhythm
c) Give adrenaline first, then restart compressions
d) Deliver another shock assuming non-perfusing rhythm
e) Obtain a 12-lead ECG immediately
Answer:
Continue chest compressions for 2 minutes before reassessing rhythm
Explanation:
In advanced life support (ALS), minimising interruptions to chest compressions is critical because coronary and cerebral perfusion rapidly fall when compressions stop.
After delivering a shock for a shockable rhythm (VF/pulseless VT), you must immediately resume CPR for 2 minutes, regardless of what appears on the monitor—unless it clearly remains a shockable rhythm.
The key principle:
- Electrical activity ≠ mechanical cardiac output
- An organised rhythm on the monitor does NOT guarantee a pulse (could be PEA)
If you stop to check a pulse immediately:
- You risk prolonged “no-flow” time
- This significantly reduces survival
Therefore:
- Continue CPR for a full 2-minute cycle
- Only then reassess rhythm and check for pulse
Other options:
- Pulse check immediately → incorrect (interrupts CPR)
- Adrenaline first → wrong sequence (should not delay CPR)
- Shock again → incorrect (organised rhythm is non-shockable)
- ECG → irrelevant during active resuscitation
Cheat Sheet (Exam-Oriented)
ALS Core Rule:
- After ANY shock → resume CPR immediately for 2 minutes
Rhythm Categories:
- Shockable → VF / pulseless VT
- Non-shockable → PEA / asystole
Golden Principles:
- Do NOT trust monitor rhythm alone
- Do NOT check pulse immediately after shock
- Do NOT interrupt compressions unnecessarily
Drug Timing:
- Adrenaline in VF/VT → after 3rd shock
- Repeat every 3–5 minutes
Cycle:
Shock → CPR 2 min → rhythm check → repeat
Flashcards
Q1: After defibrillation, what is the immediate step?
A: Resume CPR for 2 minutes
Explanation: Prevents interruption and maintains perfusion
Q2: Does an organised rhythm mean ROSC?
A: No
Explanation: Could be pulseless electrical activity
Q3: When should pulse be checked?
A: After a 2-minute CPR cycle
Explanation: Avoids unnecessary pauses
Q4: Which rhythms are shockable?
A: VF and pulseless VT
Explanation: Only these require defibrillation
Q5: When is adrenaline given in VF arrest?
A: After the 3rd shock
Explanation: Then every 3–5 minutes
MCQs (High-Level)
MCQ 1
After delivering a shock in VF arrest, the monitor shows a sinus rhythm. What is the next step?
a) Check carotid pulse immediately
b) Resume CPR for 2 minutes
c) Give amiodarone
d) Deliver another shock
Answer: b
Explanation: Rhythm change does not confirm perfusion; continue CPR
MCQ 2
Which statement about ALS is FALSE?
a) Pulse check should be done immediately after shock
b) CPR should be resumed immediately after defibrillation
c) VF is a shockable rhythm
d) Interruptions in CPR should be minimised
Answer: a
Explanation: Pulse check is delayed until after 2-minute cycle
MCQ 3
Organised electrical activity without pulse is termed:
a) Asystole
b) Ventricular tachycardia
c) Pulseless electrical activity
d) Ventricular fibrillation
Answer: c
Explanation: Electrical rhythm present but no mechanical output
MCQ 4
Which is the MOST important determinant of survival in cardiac arrest?
a) Early adrenaline
b) Continuous chest compressions
c) Early ECG
d) Oxygen therapy
Answer: b
Explanation: Coronary perfusion depends on uninterrupted compressions
MCQ 5
In VF arrest, adrenaline is first given:
a) Immediately after first shock
b) Before CPR
c) After third shock
d) Only if ROSC occurs
Answer: c
Explanation: Standard ALS protocol
MCQ 6
Which rhythm requires defibrillation?
a) Asystole
b) PEA
c) Ventricular fibrillation
d) Sinus bradycardia
Answer: c
Explanation: Only VF/pulseless VT are shockable
Summary for Quick Exam Revision
In advanced life support, the most critical principle is minimizing interruptions to chest compressions, as perfusion rapidly declines when CPR is paused. After delivering a defibrillation shock for ventricular fibrillation or pulseless ventricular tachycardia, CPR must be resumed immediately for 2 minutes regardless of any apparent rhythm change on the monitor. An organised rhythm does not guarantee return of spontaneous circulation, as it may represent pulseless electrical activity. Pulse checks should only be performed after completing a full 2-minute CPR cycle to avoid unnecessary interruptions. Only VF and pulseless VT are shockable rhythms, while PEA and asystole are non-shockable. Adrenaline in shockable rhythms is administered after the third shock and then every 3–5 minutes. The ALS algorithm follows a structured loop of shock, CPR, reassessment, and repetition. Continuous high-quality chest compressions remain the single most important determinant of survival in cardiac arrest.