Adult Cardiac Arrest Algorithm

1 Start CPR

• Call for help and the defibrillator
• Compressions 100–120/min, at least 2 inches deep, full recoil, minimal pauses
• Give oxygen; attach monitor and pads

Check the rhythm → step 2

2 Is the rhythm shockable?

Yes: VF or pulseless VT → step 3No: asystole or PEA → step 4

3 Shock, then CPR 2 minutes

• Biphasic: manufacturer dose (120–200 J), or the maximum if unknown; monophasic 360 J
• Resume compressions immediately after the shock
• IV or IO access

Rhythm check: still shockable → step 5Rhythm check: not shockable → step 4Signs of ROSC → step 6

4 CPR 2 minutes, epinephrine as soon as possible

• Epinephrine 1 mg IV/IO now, then every 3–5 minutes
• Consider an advanced airway and capnography
• Look hard for a reversible cause

Review the Hs and Ts → step 7Rhythm check: shockable → step 3Rhythm check: not shockable → step 4Signs of ROSC → step 6

5 Shock, CPR 2 minutes, epinephrine

• Epinephrine 1 mg IV/IO every 3–5 minutes
• Consider an advanced airway and waveform capnography
• With an advanced airway: 1 breath every 6 seconds with continuous compressions

Rhythm check: still shockable → step 8Rhythm check: not shockable → step 4Signs of ROSC → step 6

6 ROSC: post-arrest care

• SpO₂ 90–98%; PaCO₂ 35–45; MAP 65 or more (AHA 2025)
• 12-lead ECG: emergent cath for STEMI
• Comatose: temperature control, avoid fever
• Treat the cause

End of this path.

7 Reversible causes

• Hypovolemia, Hypoxia, Hydrogen ion (acidosis), Hypo- or hyperkalemia, Hypothermia
• Tension pneumothorax, Tamponade, Toxins, Thrombosis (pulmonary), Thrombosis (coronary)

Back to CPR → step 4

8 Shock, CPR 2 minutes, antiarrhythmic

• Amiodarone 300 mg IV/IO, then 150 mg for a second dose
• Or lidocaine 1–1.5 mg/kg, then 0.5–0.75 mg/kg
• Treat reversible causes (Hs and Ts)

Rhythm check: still shockable → step 5Rhythm check: not shockable → step 4Signs of ROSC → step 6