Cardiac Emergencies (ACLS) Flashcards

The 'Hs and Ts' of cardiac arrest represent potentially reversible causes. Which is an 'H'?

Answer: Hypovolaemia

The Hs are: Hypovolaemia, Hypoxia, Hydrogen ion excess (acidosis), Hypo/hyperkalaemia, and Hypothermia. The Ts are: Tension pneumothorax, Tamponade, Toxins, and Thrombosis (PE or coronary).

STEMI recognition on a 12-lead ECG requires ST elevation of at least:

Answer: 1mm in two or more contiguous limb leads or 2mm in two or more contiguous precordial leads

STEMI criteria: ≥1mm ST elevation in two contiguous limb leads or ≥2mm in two contiguous precordial leads (V1-V6), with specific modified criteria for left bundle branch block and posterior MI.

The pre-hospital 12-lead ECG transmission to the cardiac catheterisation laboratory is important because:

Answer: It enables the cath lab to activate and prepare before the patient arrives, reducing door-to-balloon time

Pre-hospital ECG transmission and 'cath lab activation' protocols allow the interventional cardiology team to be ready before patient arrival, reducing the total ischaemic time (first medical contact to balloon) in STEMI.

Complete AV block (third-degree heart block) with bradycardia causing haemodynamic compromise is treated pre-hospital with:

Answer: Transcutaneous pacing (TCP) as first-line, with atropine 0.5mg IV if pacing is unavailable

TCP provides immediate rate control in complete AV block with haemodynamic compromise; atropine may increase ventricular rate as a temporising measure, but the definitive pre-hospital treatment is transcutaneous pacing.

Atropine is indicated in which cardiac emergency?

Answer: Symptomatic sinus bradycardia or first/second-degree (Mobitz I) AV block

Atropine blocks vagal tone to increase heart rate — effective for sinus bradycardia and nodal blocks; it is not effective for infranodal complete AV block and is not indicated in VF/pVT.

The maximum compression depth for adult CPR according to current guidelines is:

Answer: At least 5cm but not more than 6cm

Current guidelines recommend 5-6cm compression depth in adults to generate adequate cardiac output during CPR; compressions deeper than 6cm are associated with increased injury risk without additional survival benefit.