ACLS & Cardiac Emergencies

ACLS Cardiac Arrest Algorithm

ACLS builds on BLS. The rhythm determines the treatment pathway. First: confirm arrest, start CPR, attach monitor/defibrillator.

Shockable Rhythms: VF / Pulseless VT

• CPR → Shock (200J biphasic) → Immediate CPR (2 min)
• IV/IO access during CPR — do not stop compressions for this
• Epinephrine 1 mg IV/IO every 3–5 minutes (give after 1st or 2nd shock, then every other 2-min cycle)
• If still in VF/pulseless VT after 3rd shock: Amiodarone 300 mg IV/IO push. Repeat 150 mg if still refractory.
• Lidocaine 1–1.5 mg/kg if amiodarone unavailable
• Consider and treat reversible causes (H's and T's) throughout

Non-Shockable Rhythms: PEA / Asystole

• CPR → IV/IO access → Epinephrine 1 mg IV/IO ASAP, repeat every 3–5 min
• No defibrillation — the rhythm won't respond to shock
• Focus on identifying and treating the underlying cause
• Asystole: confirm in two leads. Asystole that truly has no reversible cause is rarely survivable.

The H's and T's — Reversible Causes of Cardiac Arrest

STEMI Recognition on 12-Lead ECG

In ERLC, STEMI recognition means knowing which territory is affected so you can communicate it and route to the right facility. ST elevation ≥1mm in 2 contiguous leads in the same territory = STEMI until proven otherwise.

Territory	Leads with ST Elevation	Artery (IRL)	Clinical Notes
Inferior	II, III, aVF	RCA (85%)	Most common. Check for RV involvement (V4R). Nitro with caution — can cause severe hypotension in RV MI.
Anterior	V1–V4	LAD	Largest territory. Highest mortality. May need pacing for complete heart block.
Lateral	I, aVL, V5–V6	LCx	Often accompanies inferior or anterior MI.
Posterior	ST depression V1–V3, tall R wave	RCA/LCx	Mirror image pattern — depression in anterior leads = posterior elevation. Reciprocal changes.

Cardioversion vs. Defibrillation

	Defibrillation	Synchronized Cardioversion
When	Pulseless VF or pVT	Unstable tachyarrhythmia WITH a pulse (SVT, AF, VT with pulse)
Synchronization	Unsynchronized — fires immediately	Synchronized — fires on the R wave
Energy (biphasic)	200J (or device-specific)	SVT: 50–100J start. VT with pulse: 100J start. AF: 120–200J
Sedation	Not needed (patient is in arrest)	Sedate if conscious (midazolam 2–5 mg IV)
Risk	Converts VF → shockable rhythm cleared	Must be synchronized — unsynchronized shock during T-wave can cause VF

Cardiac Arrest Medications

Drug	Dose	Indication	Key Points
Epinephrine	1 mg IV/IO q3–5min	All cardiac arrest rhythms	First drug in arrest. Alpha effects vasoconstrict → increases coronary perfusion pressure.
Amiodarone	300 mg IV push, repeat 150 mg	Refractory VF/pVT after 3rd shock	Broadest antiarrhythmic. Hypotension common with IV push.
Lidocaine	1–1.5 mg/kg IV	Alternative to amiodarone	Use if amiodarone unavailable. May repeat 0.5–0.75 mg/kg q5–10min, max 3 mg/kg.
Adenosine	6 mg rapid IV push, flush; 12 mg if needed	Stable narrow-complex SVT	Half-life <10 seconds. Must be given rapid push with 20 mL saline flush. Antecubital or above.
Atropine	0.5 mg IV q3–5min, max 3 mg	Symptomatic bradycardia	Not effective in complete heart block. Not used in arrest per current ACLS.

Transcutaneous Pacing

Indicated for: symptomatic bradycardia not responding to atropine, complete heart block, second-degree type II block. Requires the patient to have some cardiac activity (not for asystole).

• Apply pacing pads (anterior-posterior preferred)
• Set rate to 60–80 bpm (or whatever achieves capture)
• Increase mA until electrical capture (pacing spike followed by wide QRS) — usually 60–80 mA
• Verify mechanical capture — check pulse
• Sedate and analgesia: midazolam + fentanyl — pacing is painful