DCAS Cardiac Emergencies (ACLS) 4 — Questions and Answers
Question 1: In ACLS, 'no-flow time' refers to:
- The interval between cardiac arrest and initiation of CPR (time without any perfusion) (Correct answer)
- Total duration of resuscitation
- Time without defibrillation
- Duration of poor-quality CPR
Correct answer: The interval between cardiac arrest and initiation of CPR (time without any perfusion)
No-flow time is the critical period between cardiac arrest and first CPR compression during which no cardiac output occurs; minimising this time is the single most important factor in improving OHCA survival.
Question 2: Lidocaine 1-1.5mg/kg IV is an alternative to amiodarone for shock-refractory VF/pVT when:
- Amiodarone is unavailable (Correct answer)
- The patient has renal failure
- The patient is paediatric
- The patient has a known allergy to contrast media
Correct answer: Amiodarone is unavailable
Lidocaine is recommended as an alternative antiarrhythmic when amiodarone is unavailable for shock-refractory VF/pVT; while amiodarone has superior evidence, lidocaine remains an acceptable alternative.
Question 3: The ACLS guideline recommendation for CPR compression rate is:
- 100-120 compressions per minute (Correct answer)
- 80-100 compressions per minute
- 130-150 compressions per minute
- As fast as possible without rate limit
Correct answer: 100-120 compressions per minute
Compression rates of 100-120/min optimise cardiac output during CPR; rates above 120/min reduce compression depth and below 100/min reduce perfusion — both extremes worsen outcomes.
Question 4: Which ECG finding during cardiac arrest indicates a shockable rhythm?
- Ventricular fibrillation (VF) or pulseless ventricular tachycardia (pVT) (Correct answer)
- Asystole
- Narrow-complex PEA
- Sinus bradycardia with pulse
Correct answer: Ventricular fibrillation (VF) or pulseless ventricular tachycardia (pVT)
Only VF and pVT are shockable rhythms in cardiac arrest; asystole and PEA are non-shockable and treated with CPR plus epinephrine. Rhythms with pulses are not cardiac arrest rhythms.
Question 5: Airway management during CPR should prioritise:
- High-quality continuous compressions over airway interventions — don't interrupt compressions for prolonged intubation attempts (Correct answer)
- Immediate intubation before starting CPR
- Bag-valve-mask ventilation only throughout resuscitation
- Supraglottic airways are never appropriate during CPR
Correct answer: High-quality continuous compressions over airway interventions — don't interrupt compressions for prolonged intubation attempts
Current guidelines de-emphasise early intubation during CPR, as interruptions to compressions for intubation worsen outcomes; BVM ventilation is acceptable, and intubation should be performed without interrupting compressions.
Question 6: Post-cardiac arrest care includes targeting which oxygen saturation to avoid hyperoxia?
- 94-98% (avoiding both hypoxia and hyperoxia) (Correct answer)
- 100% (maximum oxygenation)
- 88-92% (permissive hypoxaemia)
- No specific target — maximise FiO2
Correct answer: 94-98% (avoiding both hypoxia and hyperoxia)
Both hypoxia and hyperoxia are harmful post-ROSC; hyperoxia (PaO2 >300 mmHg) is associated with worse neurological outcomes due to increased oxidative stress; titrate oxygen to 94-98% SpO2.
DCAS Cardiac Emergencies (ACLS) 4
In ACLS, 'no-flow time' refers to: