ACLS Electrical Therapies and Defibrillation 1 — Questions and Answers
Question 1: What is the recommended initial energy dose for defibrillation of ventricular fibrillation (VF) using a biphasic defibrillator?
- 100 J
- 120–200 J (Correct answer)
- 300 J
- 360 J
Correct answer: 120–200 J
ACLS guidelines recommend 120–200 J for initial biphasic defibrillation, with the specific dose depending on the manufacturer's recommendation.
Question 2: Which of the following rhythms requires synchronized cardioversion rather than unsynchronized defibrillation?
- Ventricular fibrillation
- Pulseless ventricular tachycardia
- Unstable atrial fibrillation with a pulse (Correct answer)
- Asystole
Correct answer: Unstable atrial fibrillation with a pulse
Synchronized cardioversion is used for organized rhythms with a pulse (e.g., unstable AF, SVT, stable VT), while unsynchronized defibrillation is reserved for pulseless rhythms and VF.
Question 3: What is the recommended initial energy for synchronized cardioversion of unstable atrial fibrillation using a biphasic device?
- 25–50 J
- 50–100 J
- 120–200 J (Correct answer)
- 300–360 J
Correct answer: 120–200 J
For unstable atrial fibrillation, ACLS recommends an initial biphasic energy of 120–200 J for synchronized cardioversion.
Question 4: Where should defibrillator pads be placed in the standard anterolateral position?
- Right subclavicular and left lower rib cage lateral to the left nipple (Correct answer)
- Left subclavicular and right lower rib cage lateral to the right nipple
- Both pads on the left chest wall
- Right upper chest and right lower rib cage
Correct answer: Right subclavicular and left lower rib cage lateral to the left nipple
Standard anterolateral placement is right infraclavicular (below right clavicle) and left lateral chest (V4-V6 level, lateral to left nipple).
Question 5: When using a monophasic defibrillator for VF, what energy level should be used for all shocks?
- 100 J
- 200 J
- 300 J
- 360 J (Correct answer)
Correct answer: 360 J
Monophasic defibrillators deliver 360 J for all shocks during VF/pVT because they are less efficient than biphasic devices and require higher energy.
Question 6: After delivering a defibrillation shock, what should be done immediately?
- Check the pulse and rhythm before resuming CPR
- Resume CPR immediately, starting with chest compressions (Correct answer)
- Administer epinephrine before resuming CPR
- Check the rhythm for 30 seconds to assess response
Correct answer: Resume CPR immediately, starting with chest compressions
After defibrillation, CPR should be immediately resumed starting with chest compressions to maintain perfusion, with a rhythm check performed after 2 minutes.
Question 7: What is the primary purpose of the synchronization feature on a cardioverter-defibrillator?
- To charge the device faster for rapid delivery
- To deliver the shock during the refractory period of the cardiac cycle to avoid the T-wave (Correct answer)
- To reduce the energy required for defibrillation
- To prevent accidental shock to bystanders
Correct answer: To deliver the shock during the refractory period of the cardiac cycle to avoid the T-wave
Synchronization times shock delivery to coincide with the R-wave (avoiding the vulnerable T-wave period), reducing the risk of inducing VF during cardioversion.
ACLS Electrical Therapies and Defibrillation 1
What is the recommended initial energy dose for defibrillation of ventricular fibrillation (VF) using a biphasic defibrillator?