ACLS Algorithms for the Paramedic NREMT

The ACLS algorithms the NREMT paramedic exam tests most heavily are cardiac arrest (VF/pulseless VT and asystole/PEA), symptomatic bradycardia, tachycardia (stable and unstable), and immediate post-cardiac-arrest (post-ROSC) care. On the exam you are rarely asked to simply recite a dose — you are asked to recognize a rhythm, decide the next best action, and apply the algorithm in the right order. Mastering the flow of each algorithm, and the branch points where decisions change, is what earns points.

This guide walks through each major ACLS algorithm from a paramedic's perspective, builds memory hooks, and flags the branch points NREMT loves to test. Always defer to your medical director's protocols for exact dosing and sequencing in the field; the versions below reflect mainstream AHA guidance for study purposes.

How the NREMT Frames ACLS Questions

The computer-adaptive NREMT paramedic exam includes a Cardiology & Resuscitation domain worth 10–14% of the exam, and ACLS scenarios show up throughout. Rather than asking "What is the dose of epinephrine?", a typical item describes a scene — a 62-year-old found pulseless, a monitor strip, CPR already in progress — and asks for the next most appropriate step.

That phrasing matters. The exam rewards candidates who keep priorities straight:

• High-quality CPR and early defibrillation beat every drug.
• Reversible causes (the Hs and Ts) drive decisions in PEA and asystole.
• Rhythm interpretation determines which branch of the algorithm you follow.

If you can look at a scenario and instantly classify it — is this a shockable rhythm? is the patient stable or unstable? is the QRS wide or narrow? — you will answer most ACLS items correctly even when you blank on an exact dose. Build that classification reflex first.

Before you go deep, it helps to know which domain is actually dragging your score. A quick free NREMT diagnostic is a one-time, 20-question, batch-graded snapshot (no timer, no rationales) that shows whether Cardiology is your weak spot or whether your study time belongs elsewhere.

The Cardiac Arrest Algorithm (VF/pVT and Asystole/PEA)

Every adult cardiac arrest starts the same way: confirm unresponsiveness and pulselessness, start high-quality CPR, attach the monitor/defibrillator, and get oxygen going. The first fork comes when you read the rhythm.

Shockable: VF and Pulseless VT

For ventricular fibrillation or pulseless ventricular tachycardia, the priority is defibrillation as early as possible. After the first shock, resume CPR immediately for about two minutes before reanalyzing — do not stop to check a pulse right after the shock.

The repeating cycle looks like this:

1. Shock.
2. 2 minutes of CPR with minimal interruptions.
3. Rhythm check; shock again if still shockable.
4. Give epinephrine every 3–5 minutes after the second shock.
5. Consider an antiarrhythmic (amiodarone or lidocaine) for refractory VF/pVT.
6. Search for and treat reversible causes.

Non-shockable: Asystole and PEA

Asystole and pulseless electrical activity share one branch. There is nothing to shock, so the emphasis shifts to CPR, early epinephrine, and aggressively hunting reversible causes. Confirm asystole in more than one lead and check lead/pad connections before you call it — a flatline can be an artifact.

The Hs and Ts

Reversible causes are the single highest-yield list in the cardiac arrest algorithm, especially for PEA and asystole:

• Hs: Hypovolemia, Hypoxia, Hydrogen ion (acidosis), Hypo-/Hyperkalemia, Hypothermia.
• Ts: Tension pneumothorax, Tamponade (cardiac), Toxins, Thrombosis (pulmonary), Thrombosis (coronary).

When a PEA scenario gives you a hint — a trauma patient (hypovolemia), a dialysis patient who missed treatment (hyperkalemia), a hanging or drowning (hypoxia) — the "best next step" is usually to treat that cause, not just push another round of epi.

Symptomatic Bradycardia

The bradycardia algorithm applies when a heart rate under roughly 50 produces symptoms of poor perfusion — hypotension, altered mental status, chest pain, signs of shock, or acute heart failure. A slow rate alone, in a well-perfused athlete, is not an emergency.

The sequence is:

1. Maintain airway, give oxygen if hypoxic, obtain IV access and a 12-lead.
2. Atropine is first-line for symptomatic bradycardia.
3. If atropine fails or the block is likely high-grade (second-degree type II or third-degree), move to transcutaneous pacing and/or a chronotropic infusion (dopamine or epinephrine).

A classic NREMT trap: atropine is often ineffective in high-degree AV blocks (Mobitz II and complete heart block) when the block is below the AV node, and it can occasionally worsen the block. For those rhythms, the better answer is to prepare for pacing. Recognizing the block on the strip is the key decision point.

Tachycardia: Stable vs. Unstable

The tachycardia algorithm hinges on one question before anything else: is the patient stable or unstable? Unstable means serious signs and symptoms caused by the fast rate — hypotension, acute altered mental status, ischemic chest pain, signs of shock, or acute heart failure.

Unstable Tachycardia

If the patient is unstable and the rate is the problem, the answer is synchronized cardioversion — except unstable polymorphic VT, which gets an immediate unsynchronized (defibrillation-dose) shock even with a pulse. Do not get lost deciding between adenosine and a beta-blocker — electricity is the priority when the patient is crashing.

Stable Tachycardia

For a stable patient, you have time to analyze the rhythm, and the QRS width guides therapy:

• Narrow, regular (likely SVT): try vagal maneuvers, then adenosine.
• Narrow, irregular (likely atrial fibrillation): rate control per protocol; adenosine is not the fix.
• Wide, regular (likely VT or SVT with aberrancy): treat as VT if uncertain; antiarrhythmic or expert consult.
• Wide, irregular: this can be dangerous (polymorphic VT, pre-excited AF) — avoid AV-nodal blockers and consult/defibrillate as indicated.

Note the difference between synchronized cardioversion (for unstable tachycardia with a pulse — the shock is timed to the R wave; unstable polymorphic VT is the exception and gets an unsynchronized shock) and unsynchronized defibrillation (for pulseless VF/VT). Mixing those two up is one of the most common ACLS errors tested.

Post-Cardiac-Arrest (Post-ROSC) Care

Return of spontaneous circulation is not the finish line. Post-ROSC care protects the brain and heart during a fragile window. Priorities include:

• Airway and ventilation: avoid both hypoxia and hyperventilation; target normal oxygenation and ventilation rather than bagging aggressively.
• Hemodynamics: support blood pressure; current AHA guidance is to avoid hypotension by keeping the mean arterial pressure at least 65 mmHg, with fluids and vasopressors per protocol.
• 12-lead ECG: identify STEMI early and plan transport to a PCI-capable center.
• Treat the cause: continue addressing the Hs and Ts that caused the arrest.
• Temperature management: follow your system's targeted temperature protocol.

On the NREMT, post-ROSC items often test the instinct to avoid over-ventilating and the need for a 12-lead and appropriate destination selection.

Common Mistakes

• Treating the monitor, not the patient. A slow or fast rate without poor-perfusion symptoms does not get aggressive treatment.
• Confusing cardioversion and defibrillation. Synchronized = unstable pulse-present tachycardia (except polymorphic VT); unsynchronized = pulseless VF/VT and unstable polymorphic VT. PEA and asystole are never shocked.
• Relying on atropine alone for high-grade AV blocks. Mobitz II and complete heart block often need pacing, so don't delay it.
• Stopping CPR too long after a shock. Resume compressions immediately; reassess at the next 2-minute cycle.
• Ignoring reversible causes in PEA/asystole. The Hs and Ts are often the intended answer.
• Over-ventilating during and after arrest. Hyperventilation reduces cardiac output and worsens outcomes.
• Memorizing doses but not the flow. The exam tests sequence and decision points more than numbers.

Study Plan and Next Steps

Work the algorithms in this order so each builds on the last:

1. Week 1 — Rhythm recognition. You cannot apply an algorithm you cannot read. Drill VF, VT, SVT, AF, the AV blocks, asystole, and PEA until classification is instant. Pair this with our paramedic cardiology review for the underlying electrophysiology.
2. Week 2 — Cardiac arrest. Memorize the shockable vs. non-shockable branches and the Hs and Ts cold.
3. Week 3 — Bradycardia and tachycardia. Focus on the stable/unstable fork and the cardioversion-vs-defibrillation distinction.
4. Week 4 — Post-ROSC and integration. Run full scenarios start to finish, out loud, as if directing a code.

To keep your practice honest, use realistic exam-style questions with explanations. The EMSQUIZ question bank and features let you drill cardiology scenarios with rationales, while the plans on our pricing page show what full access includes. Start by pinpointing your weakest domain so your algorithm review targets the right gaps.

Scope note: This article is exam-prep education, not medical advice. Always follow your medical director's protocols and current local guidelines for patient care.