Cardiovascular · Topic 23 of 48

Cardiac Arrest & ACLS

Cardiovascular · resuscitation

Cardiac Arrest & ACLS

Push hard and fast, shock VF early, give epinephrine 1 mg every 3–5 minutes, and hunt the H's and T's.

Key numbers

Compress 100–120/min, at least 5 cm deep100–120/min

Shock VF/pVT once, then resume CPR120–200 J biphasic

Epinephrine 1 mg IV every 3–5 minutes1 mg q3–5 min

Amiodarone 300 mg, then 150 mg300 mg → 150 mg

Pulse check no longer than 10 seconds≤ 10 s

01 · DoCompress 100–120/min, at least 5 cm deep

High-quality CPR: compress at 100–120/min to at least 5 cm (2 in) but not more than 6 cm (2.4 in), allow full recoil, minimize pauses and change compressors every 2 minutes.

02 · GiveEpinephrine 1 mg IV every 3–5 minutes

Give epinephrine 1 mg IV/IO every 3–5 minutes: as soon as feasible in asystole or PEA, and in VF/pVT after initial defibrillation attempts fail (after the second shock in the algorithm).

03 · GiveAmiodarone 300 mg, then 150 mg

For VF/pVT persisting after shocks (after the third shock in the algorithm) give amiodarone 300 mg IV/IO bolus, then 150 mg; lidocaine 1–1.5 mg/kg, then 0.5–0.75 mg/kg, is the alternative.

The rules

Know these

Search for the H's and T's must knowTreat reversible causes during CPR. H's: hypovolemia, hypoxia, hydrogen ion (acidosis), hypo-/hyperkalemia, hypothermia. T's: tension pneumothorax, tamponade, toxins, pulmonary thrombosis, coronary thrombosis.

Try IV access first; IO if IV failsAttempt peripheral IV access first for arrest drugs (2025, class 1); use intraosseous access if initial IV attempts fail or are not feasible, and central access only by trained clinicians after both fail.

Never stop on ETCO₂ aloneIn intubated adults, failure to reach ETCO₂ above 10 mmHg after 20 minutes of ALS may be one part of a multimodal decision to stop; no ETCO₂ cutoff should be used in nonintubated patients.

Diagnosis & monitoring

Work-up

Confirm the ETT with waveform capnographyContinuous waveform capnography is the most reliable way to confirm and monitor endotracheal tube position; defer airway placement that would interrupt compressions until initial CPR and defibrillation have failed or ROSC occurs.

ETCO₂ below 10 mmHg: improve compressionsETCO₂ reflects CPR-generated cardiac output: below 10 mmHg is associated with poor outcome and should prompt better compressions; above 10, ideally above 20 mmHg, predicts ROSC, and an abrupt rise signals ROSC.

Do right now

In this order

First moves

Compress 100–120/min, at least 5 cm deep100–120/min

→

Shock VF/pVT once, then resume CPR120–200 J biphasic

→

Epinephrine 1 mg IV every 3–5 minutes1 mg q3–5 min

→

Amiodarone 300 mg, then 150 mg300 mg → 150 mg

Why each step

Compress 100–120/min, at least 5 cm deepHigh-quality CPR: compress at 100–120/min to at least 5 cm (2 in) but not more than 6 cm (2.4 in), allow full recoil, minimize pauses and change compressors every 2 minutes.

Shock VF/pVT once, then resume CPRFor VF or pulseless VT give a single shock — biphasic at the manufacturer dose (typically 120–200 J, device maximum if unknown) or monophasic 360 J — then resume compressions immediately for 2 minutes.

Epinephrine 1 mg IV every 3–5 minutesGive epinephrine 1 mg IV/IO every 3–5 minutes: as soon as feasible in asystole or PEA, and in VF/pVT after initial defibrillation attempts fail (after the second shock in the algorithm).

Amiodarone 300 mg, then 150 mgFor VF/pVT persisting after shocks (after the third shock in the algorithm) give amiodarone 300 mg IV/IO bolus, then 150 mg; lidocaine 1–1.5 mg/kg, then 0.5–0.75 mg/kg, is the alternative.

Management

Orders

Asystole/PEA: CPR and epinephrine, no shockAsystole and PEA are nonshockable: continue CPR with rhythm checks every 2 minutes, give epinephrine as soon as feasible, and look for a reversible cause; pacing is not routinely recommended for asystolic arrest.

Pulse check no longer than 10 secondsKeep pre- and post-shock pauses as short as possible; a pulse check takes no more than 10 seconds, and if a pulse is not definitely felt, restart compressions immediately.

Advanced airway: 1 breath every 6 secondsWithout an advanced airway use a 30:2 compression–ventilation ratio; once an endotracheal tube or supraglottic airway is placed, give 1 breath every 6 seconds (10/min) with continuous compressions and avoid overventilation.

Vasopressin adds nothing to epinephrineVasopressin, alone or combined with epinephrine, offers no advantage as a substitute for epinephrine, and high-dose epinephrine is not recommended.

Pregnancy: displace uterus, deliver within 5 minutesIn arrest with fundal height at or above the umbilicus: continuous left lateral uterine displacement, IV above the diaphragm, stop IV magnesium and give calcium, and aim for resuscitative delivery by 5 minutes without ROSC.

Red flags & don'ts

Avoid harm

No routine calcium, bicarbonate or magnesium avoidRoutine calcium, sodium bicarbonate and magnesium do not help in cardiac arrest; reserve them for specific causes such as hyperkalemia (calcium, bicarbonate) or torsades de pointes (magnesium).

Shockable or nonshockable arrest?

Commonly confused

First move	Single shock, then CPR for 2 minutes
Epinephrine 1 mg	After initial shocks fail
Antiarrhythmic	Amiodarone or lidocaine for persisting VF/pVT
Main search	Rhythm check and shock every 2 minutes

More detail

Reference

Show 7 reference facts

For VF/pVT persisting after 3 or more shocks, the usefulness of vector change (repositioned pads) and double sequential defibrillation is not established; most 'refractory' VF is recurrence after a successful shock.

Drug delivery through the endotracheal tube has been removed from the guidelines because it gives low, unpredictable blood levels.

Head-up CPR is not recommended outside clinical trials (new in 2025).

A single-shock strategy is preferred to stacked shocks; biphasic waveforms are preferred, and higher energy for second and later shocks may be considered if the device allows.

Beta-blockers, bretylium, procainamide and sotalol for shock-refractory VF/pVT, and steroids during arrest, are of uncertain benefit.

Point-of-care ultrasound by experienced clinicians may be considered to find reversible causes only if it does not interrupt compressions; using it to prognosticate is not well established. An arterial line can detect ROSC during compressions.

Use the maximal feasible inspired oxygen concentration during CPR; titrate oxygen only after ROSC.

Pearl

Shockable: shock, CPR, epinephrine after the second shock, amiodarone after the third. Nonshockable: CPR and epinephrine now, then the H's and T's.

Sources · 2025 AHA Guidelines for CPR and ECC — Part 9: Adult Advanced Life Support (Circulation 2025;152 suppl 2) · AHA 2025 ACLS algorithms poster set (JN-2788, 12/25): Adult Cardiac Arrest, Post–Cardiac Arrest Care, Cardiac Arrest in Pregnancy · 2025 AHA Guidelines for CPR and ECC — Part 7: Adult Basic Life Support · Merck Manual Professional — Cardiopulmonary Resuscitation (CPR) in Adults · Using transcutaneous cardiac pacing to best advantage (review) — PMC6376978 · Starter sheet built from the verified AGACNP fact map (facts reviewed 2026-10-15).