Narcan (Naloxone) and Cardiac Arrest: What You Need to Know

Naloxone (Narcan) is an opioid antagonist used to reverse opioid overdose. It is NOT a treatment for cardiac arrest.

Mechanism & Indication

• Competitively displaces opioids from mu receptors → reverses respiratory depression, sedation, hypotension.
• Indicated: Known/suspected opioid overdose with respiratory depression (RR <10, SpO₂ <90%, unresponsive).
• Dose: 0.4–2 mg IV/IM/IN; repeat q2–3 min prn; max 10 mg. IN (Narcan Nasal Spray) 4 mg/0.1 mL.

Cardiac Arrest Management

Cardiac arrest = cessation of effective cardiac output. Causes: VF/pVT, PEA, asystole. Algorithm (ACLS):

1. High-quality CPR (100–120/min, 2–2.4", full recoil, minimal interruptions)
2. Defibrillation for shockable rhythms (VF/pVT) — ASAP
3. Epinephrine 1 mg IV/IO q3–5 min
4. Airway management, capnography
5. Treat reversible causes (Hs & Ts: Hypovolemia, Hypoxia, Hydrogen ion/acidosis, Hypo-/hyperkalemia, Hypothermia, Tension pneumothorax, Tamponade, Toxins, Thrombosis coronary/pulmonary)

Naloxone in Cardiac Arrest?

• Only if opioid overdose is the presumed cause of respiratory arrest leading to cardiac arrest.
• Give naloxone during CPR if opioid involvement suspected — but do not delay defibrillation or epinephrine.
• No evidence naloxone improves outcomes in non-opioid cardiac arrest.
• Not in standard ACLS algorithm.

Key Distinction

Opioid Overdose (Respiratory Arrest)	Cardiac Arrest
Primary problem: respiratory depression	Primary problem: no effective cardiac output
Pulse usually present initially	No pulse
Naloxone = definitive treatment	CPR + defibrillation = definitive treatment
May progress to cardiac arrest if untreated	Requires ACLS algorithm

If uncertain and patient unresponsive with no normal breathing: Start CPR, call 911, give naloxone if available and opioid suspected. But naloxone does not replace CPR for cardiac arrest.