DCAS Cardiac Emergencies (ACLS) 3

Question 1

Adenosine is used to treat which arrhythmia?

Accepted Answer

Stable narrow-complex supraventricular tachycardia (SVT) with regular rhythm

Answer

Adenosine transiently blocks the AV node, terminating re-entry SVTs; its extremely short half-life (10 seconds) makes it safe even if the diagnosis is uncertain — it will terminate AV-nodal-dependent arrhythmias or cause diagnostic slowing.

Question 2

Cardioversion for unstable tachyarrhythmia is performed 'synchronised' meaning:

Accepted Answer

The shock is delivered on the R wave to avoid inducing VF

Answer

Synchronised cardioversion delivers the shock on the QRS complex (R wave), avoiding delivery during the vulnerable T wave repolarisation period which could induce ventricular fibrillation.

Question 3

A patient presents with SVT at 200 bpm, BP 90/60, diaphoretic, and confused. The ACLS treatment is:

Accepted Answer

Immediate synchronised cardioversion

Answer

Haemodynamic instability (hypotension, altered consciousness, diaphoresis) requires immediate synchronised cardioversion rather than pharmacological attempts, which take time and may fail.

Question 4

Which waveform on capnography indicates return of spontaneous circulation (ROSC) during CPR?

Accepted Answer

Sudden sustained increase in ETCO2 to >35-40 mmHg

Answer

During CPR, ETCO2 reflects cardiac output; when ROSC occurs, the heart suddenly resumes pumping blood through the lungs, causing a sudden and sustained rise in ETCO2, providing a non-invasive indicator of ROSC.

Question 5

High-quality CPR requires that chest recoil between compressions is:

Accepted Answer

Complete (full recoil between each compression) without leaning on the chest

Answer

Complete chest recoil between compressions allows ventricular filling (diastolic filling) during CPR; leaning on the chest prevents recoil, reduces venous return, and significantly reduces coronary and cerebral perfusion.

DCAS Practice Test

DCAS Practice Test

DCAS Cardiac Emergencies (ACLS) 3