Cardiac Arrest Algorithms Explained: Shockable vs Non-Shockable
How VF/pVT and PEA/asystole algorithms differ, when to shock, and the H's and T's you actually need to remember.
November 17, 2026 · 8 min read
Cardiac arrest questions on the NREMT reduce to one decision: is the rhythm shockable? Everything downstream flows from that.
Shockable: VF and pulseless VT
CPR, defibrillate, resume CPR immediately for 2 minutes. Epi 1 mg after the second shock, then every 3–5 minutes. Amiodarone 300 mg after the third shock (150 mg second dose). Reassess rhythm every 2 minutes.
Non-shockable: PEA and asystole
CPR, epi 1 mg ASAP, then every 3–5 minutes. No defibrillation. Aggressively hunt reversible causes — this is where the H's and T's live.
H's and T's that actually get tested
- Hypovolemia — fluid bolus
- Hypoxia — verify airway and oxygenation
- Hydrogen ion (acidosis) — ventilate, consider bicarb
- Hypo/hyperkalemia — calcium, bicarb, insulin/D50
- Hypothermia — active rewarming, extended resuscitation
- Tension pneumothorax — needle decompression
- Tamponade — pericardiocentesis (in-hospital)
- Toxins — antidote if known
- Thrombosis (coronary or pulmonary) — transport
Compressions are the drug
Every intervention is secondary to high-quality chest compressions: 100–120/min, 2–2.4 inches deep, full recoil, minimal interruptions. If compressions stop for the airway or IV, you're doing it wrong.
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