🫀 Core Concepts Cardiac arrest = electrical failure (VF/pVT) or mechanical/perfusion failure (Asystole/PEA). On the floor/ICU, arrests are often preceded by resp failure or hypovolemia → RR <6 or >30, HR <40 or >140, SBP <90 → activate Rapid Response. ACS pathway: plaque → rupture → thrombus → ischemia/MI. STEMI = full occlusion, NSTE-ACS = partial; ischemia makes myocardium irritable → VF. ACLS boosts chances of ROSC + neuro recovery.

🧷 Chain of Survival (STEMI) Recognize → EMS/transport + prearrival notice → ED/cath dx → reperfusion. Goals: PCI ≤90 min from first medical contact; fibrinolysis ≤30 min from ED arrival. Your job: zero delays.

🔄 Rhythms & Management

⚡ Shockable: VF / pVT

Patho/ECG: VF = chaotic, no QRS; pVT = wide, fast, pulseless. Do: CPR → Shock (biphasic 120–200 J; mono 360 J) → 2 min CPR → rhythm check. If still shockable: Shock → Epi 1 mg IV/IO q3–5 min. Next cycle: Shock → Amio 300 mg (then 150 mg) or Lido 1–1.5 mg/kg, then 0.5–0.75 mg/kg (max 3 mg/kg). Treat H’s/T’s; rotate compressors q2 min; minimize pauses. 🧠 Why: Defib ends electrical chaos so native pacemakers can resume.

🫢 Nonshockable: Asystole / PEA

Patho/ECG: Asystole = flat (check leads/gain); PEA = rhythm, no pulse (severe preload/mechanical problem). Do: CPR → Epi 1 mg IV/IO q3–5 min ASAP → NO shock → relentless H’s/T’s search (Hypovolemia, Hypoxia, H+, Hypo/Hyper-K, Hypothermia; Tension pneumo, Tamponade, Toxins, Thrombosis pulm/coronary). 🧠 Why: Vasoconstriction ↑ aortic diastolic P → ↑ CPP during CPR; fixing the cause is the win.

🐢 Bradycardia (symptomatic, HR <50)

Airway/O₂/monitor/IV/12-lead. Atropine 1 mg IV q3–5 min (max 3 mg). If ineffective: TCP, Dopamine 5–20 mcg/kg/min or Epi 2–10 mcg/min. ⚠️ Often ineffective in Mobitz II/3° block w/ wide QRS and transplant → pace early. Sedate for TCP if conscious.

🚀 Tachycardia (HR >150)

Unstable: Synchronized cardioversion NOW (sedate if possible). Stable narrow regular (SVT): vagal → Adenosine 6 mg, then 12 mg rapid IV push. Stable wide regular: consider Amio 150 mg over 10 min (or procainamide). ⚠️ Never AV nodal blockers (Adenosine/BB/CCB) in irregular wide-complex (likely pre-excited AF) → can provoke VF.

💊 Meds (adult highlights)

Epinephrine: Arrest 1 mg IV/IO q3–5 min; Brady 2–10 mcg/min. Flush 20 mL + elevate limb. Amiodarone: VF/pVT refractory 300 mg, then 150 mg; maint 1 mg/min ×6 h. Lidocaine: 1–1.5 mg/kg, then 0.5–0.75 mg/kg (max 3 mg/kg). Magnesium: 1–2 g for torsades. Atropine: 1 mg IV (max 3 mg). Adenosine: 6 mg → 12 mg rapid push + flush.