ACLS Algorithm | Advanced Cardiac Life Support Protocol

CRITICAL Adult Cardiac Arrest Algorithm

AHA 2020 Guidelines — Assess rhythm every 2 minutes. Minimize interruptions in chest compressions.

1. Confirm Cardiac Arrest

Unresponsive, no breathing or only gasping
No definite pulse within 10 seconds
Activate Emergency Response / Call for defibrillator

2. Start High-Quality CPR

Rate: 100–120 compressions/min
Depth: At least 2 inches (5 cm), not exceeding 2.4 inches (6 cm)
Recoil: Allow complete chest recoil between compressions
Ratio: 30:2 (no advanced airway) or continuous (with advanced airway, 1 breath every 6 sec)
Minimize interruptions: <10 sec for rhythm checks
Rotate compressors every 2 minutes

3. Rhythm Analysis — Shockable?

VF / Pulseless VT (Shockable)

Defibrillate: Biphasic 120–200 J (or manufacturer dose); Monophasic 360 J
Resume CPR immediately × 2 min
If refractory after 2nd shock → Epinephrine 1 mg IV/IO q3–5 min
After 3rd shock → Amiodarone 300 mg IV/IO bolus (2nd dose: 150 mg) OR Lidocaine 1–1.5 mg/kg (then 0.5–0.75 mg/kg)
Consider: Double sequential defibrillation for refractory VF

PEA / Asystole (Non-Shockable)

Epinephrine 1 mg IV/IO ASAP then q3–5 min
Resume CPR × 2 min
Recheck rhythm every 2 min
If organized rhythm → check pulse
Aggressively search for reversible causes (H's & T's)
Consider: Advanced airway, waveform capnography (ETCO₂ >10 mmHg target)

4. During CPR — Continuous Reassessment

Waveform capnography: ETCO₂ <10 mmHg = improve CPR quality
IV/IO access
Advanced airway (ETT or supraglottic) — do not delay compressions
Treat reversible causes (H's & T's)
If ROSC → go to Post-Cardiac Arrest Care

CPR Quality Metrics

100–120

Compressions/min

≥5 cm

Depth (≤6 cm)

>80%

CCF Target

CCF = Chest Compression Fraction. Minimize pauses. ETCO₂ >10 mmHg indicates adequate compressions. Sudden rise in ETCO₂ ≥40 mmHg may indicate ROSC.

UNSTABLE Adult Bradycardia Algorithm

HR <60 bpm with inadequate perfusion. Identify and treat underlying cause.

1. Assess Adequacy of Perfusion

Signs/symptoms: Hypotension, altered mental status, chest pain, acute heart failure, shock
If adequate perfusion → observe and monitor
If signs of poor perfusion → treat immediately

2. First-Line: Atropine

Atropine 1 mg IV every 3–5 min (max 3 mg total)
May be ineffective in: Mobitz Type II, 3rd degree AV block, infra-nodal block
Do NOT rely on atropine for transplanted hearts (denervated)

3. If Atropine Ineffective

Transcutaneous Pacing

Start at 60–80 mA, increase until capture
Rate 60–80 bpm
Verify mechanical capture (pulse)
Consider sedation/analgesia

Chronotropic Infusions

Dopamine: 5–20 mcg/kg/min IV
Epinephrine: 2–10 mcg/min IV
Isoproterenol: 2–10 mcg/min (if available)

4. Definitive: Transvenous Pacing

Consult cardiology for transvenous pacemaker
Consider permanent pacemaker if cause not reversible

Key Bradycardia Differentials

Sinus Bradycardia: Normal P waves, regular, responds to atropine

1° AV Block: PR >200 ms, usually benign, observe

Mobitz Type I (Wenckebach): Progressive PR prolongation → dropped beat. Usually benign.

Mobitz Type II: Fixed PR then sudden drop. HIGH risk of progression → pace early.

3° (Complete) AV Block: AV dissociation. Wide escape = unstable. Pace immediately.

Drug-induced: Beta-blockers, CCBs, digoxin, amiodarone. Treat cause + temporize.

CRITICAL Adult Tachycardia with Pulse Algorithm

HR >150 bpm usually symptomatic. Assess stability first.

1. Assess Hemodynamic Stability

UNSTABLE (any of the following):

Hypotension, acute AMS, chest pain, acute HF → Immediate synchronized cardioversion

Narrow regular: 50–100 J
Narrow irregular (AFib): 120–200 J biphasic
Wide regular: 100 J
Wide irregular: Defibrillation (treat as VF) — DO NOT synchronize

2. Stable — Determine QRS Width

Narrow QRS (≤0.12 sec)

Regular:

Vagal maneuvers (modified Valsalva, carotid sinus massage)
Adenosine 6 mg rapid IV push → if no effect → 12 mg → may repeat 12 mg once
If SVT: Adenosine is diagnostic AND therapeutic
If adenosine fails: CCB (diltiazem 15–20 mg IV) or BB (metoprolol 5 mg IV)

Irregular (likely AFib/AFlutter):

Rate control: Diltiazem, BB, or digoxin
Consider anticoagulation (CHA₂DS₂-VASc)
If <48 hrs: may cardiovert with anticoagulation

Wide QRS (>0.12 sec)

Regular (VT or uncertain):

Amiodarone 150 mg IV over 10 min, may repeat; then 1 mg/min × 6 hrs
OR Procainamide 20–50 mg/min (max 17 mg/kg); stop if QRS widens >50% or hypotension
OR Sotalol 100 mg (1.5 mg/kg) IV over 5 min
If definitely SVT with aberrancy → treat as narrow complex
If uncertain: treat as VT

Irregular (AFib with WPW or polymorphic VT):

AFib + WPW: AVOID AV nodal blockers (adenosine, CCB, digoxin, BB) — use procainamide or cardiovert
Polymorphic VT (Torsades): Magnesium 1–2 g IV, defibrillate if unstable, overdrive pacing

Cardioversion Energy Doses

Rhythm	Initial Dose	Notes
SVT / AFlutter	50–100 J	Synchronized
AFib	120–200 J (biphasic)	Synchronized
Monomorphic VT	100 J	Synchronized
Polymorphic VT / VF	120–200 J (biphasic)	Unsynchronized (Defibrillation)

ROSC Post-Cardiac Arrest Care

Systematic approach after return of spontaneous circulation. Focus on organ preservation.

1. Airway & Ventilation

Secure advanced airway (ETT preferred); confirm placement with waveform capnography
Target SpO₂ 92–98% — avoid hyperoxia (titrate FiO₂ down)
Target PaCO₂ 35–45 mmHg — avoid hyperventilation
Ventilator: RR 10–12, TV 6–8 mL/kg IBW

2. Hemodynamic Optimization

Target SBP ≥90 mmHg / MAP ≥65 mmHg
IV fluid bolus if hypovolemic
Vasopressors: Norepinephrine (first-line) or epinephrine infusion
12-lead ECG ASAP — evaluate for STEMI
STEMI or high suspicion of coronary occlusion → emergent PCI (regardless of coma status)
Echocardiography to assess LV function, RV strain, tamponade

3. Targeted Temperature Management (TTM)

Target: 32–36°C for ≥24 hours (select constant temperature)
Indication: Comatose patients (GCS <8) after ROSC from any initial rhythm
Methods: Surface cooling, intravascular cooling devices, cold IV fluids (adjunct only)
Actively prevent fever (>37.7°C) for at least 72 hours
Rewarm slowly: 0.25–0.5°C per hour
Monitor: Core temp, shivering (manage with sedation/paralysis), electrolytes (K⁺, Mg²⁺)

4. Neuroprognostication

Wait ≥72 hours after ROSC (or rewarming) before prognostication
Multimodal approach: Clinical exam, EEG, SSEP, NSE, MRI brain
Absent pupillary/corneal reflexes at ≥72 hrs = poor prognosis indicator
No single test should be used in isolation

5. Seizure Management & General ICU Care

Continuous EEG monitoring recommended
Treat clinical seizures: Levetiracetam, valproate, benzodiazepines
Glucose: Target 140–180 mg/dL (avoid hypoglycemia)
Prevent and treat: Myoclonus, infections, DVT prophylaxis

ACLS Pharmacology Quick Reference

Epinephrine (Adrenaline)

Cardiac Arrest: 1 mg IV/IO every 3–5 min

Bradycardia/Post-ROSC infusion: 2–10 mcg/min IV

Anaphylaxis: 0.3–0.5 mg IM (1:1000)

MOA: α₁ (vasoconstriction → ↑CPP) + β₁ (↑HR, contractility)

Amiodarone

VF/pVT Arrest: 300 mg IV bolus → 150 mg (2nd dose)

Stable VT: 150 mg IV over 10 min → 1 mg/min × 6 hrs → 0.5 mg/min × 18 hrs

MOA: Class III (K⁺ channel block) + Class I, II, IV properties. Prolongs AP & refractoriness.

Caution: Hypotension, bradycardia, QT prolongation. Contraindicated with other QT-prolonging agents.

Lidocaine

VF/pVT Arrest: 1–1.5 mg/kg IV → 0.5–0.75 mg/kg q5–10 min (max 3 mg/kg)

Maintenance: 1–4 mg/min infusion

MOA: Class IB Na⁺ channel blocker. Alternative to amiodarone.

Adenosine

SVT: 6 mg rapid IV push → 12 mg → 12 mg (each followed by 20 mL NS flush + arm elevation)

MOA: A₁ receptor → ↓AV node conduction. Half-life <10 sec. Administer via proximal/central line preferred.

Caution: Bronchospasm (relative CI in asthma). Reduce dose if on carbamazepine or transplant (start 3 mg). Increase dose if on caffeine/theophylline.

Atropine

Bradycardia: 1 mg IV every 3–5 min (max 3 mg)

MOA: Muscarinic (M₂) antagonist → ↑SA node firing, ↑AV conduction. Ineffective in infranodal block.

Magnesium Sulfate

Torsades de Pointes: 1–2 g IV over 5–20 min (dilute in 10 mL D5W)

Cardiac Arrest (Torsades): 1–2 g IV push

MOA: Membrane stabilizer, suppresses EADs, corrects hypomagnesemia.

Procainamide

Stable Wide-Complex Tachycardia: 20–50 mg/min IV until: arrhythmia suppressed, hypotension, QRS widens >50%, or max dose 17 mg/kg

Maintenance: 1–4 mg/min

MOA: Class IA Na⁺ channel blocker. Preferred in WPW + AFib. Avoid with QT prolongation or CHF.

Dopamine

Bradycardia: 5–20 mcg/kg/min IV infusion (chronotropic)

Dose-dependent: 1–5 (renal), 5–10 (β₁ cardiac), 10–20 (α₁ vasopressor). Alternative to pacing bridge.

Calcium Chloride / Gluconate

Hyperkalemia, Ca²⁺ channel blocker OD, Hypocalcemia:

CaCl₂ 10%: 500–1000 mg (5–10 mL) IV over 2–5 min (central line preferred)

Ca Gluconate: 1–3 g IV (peripheral safe)

MOA: Membrane stabilizer. Does NOT lower K⁺ — only antagonizes cardiac effects.

Sodium Bicarbonate

Hyperkalemia, TCA OD, severe metabolic acidosis: 1 mEq/kg IV

NOT recommended as routine in cardiac arrest. Consider if pre-existing metabolic acidosis, hyperK⁺, or TCA poisoning.

Reversible Causes — The H's & T's

Search aggressively during CPR. Treating the underlying cause is essential for ROSC, especially in PEA/Asystole.

The H's

Hypovolemia

Signs: Narrow-complex PEA, flat neck veins, hx trauma/bleeding

Rx: Volume resuscitation (crystalloid, blood products), source control

Hypoxia

Signs: Cyanosis, prior respiratory distress, low SpO₂

Rx: Advanced airway, confirm placement, 100% O₂, bilateral chest rise

Hydrogen Ion (Acidosis)

Signs: Prolonged arrest, DKA, renal failure, sepsis, drug OD

Rx: NaHCO₃ 1 mEq/kg IV, hyperventilation, treat underlying cause

Hyperkalemia / Hypokalemia

Signs: Peaked T waves, wide QRS, sine wave (hyperK); flat T, U waves (hypoK)

Rx HyperK: CaCl₂, NaHCO₃, insulin+glucose, albuterol, kayexalate, dialysis

Rx HypoK: IV KCl replacement (10–20 mEq/hr, max 40 mEq/hr with monitoring)

Hypothermia

Signs: Environmental exposure, core temp <30°C, Osborn (J) waves

Rx: Active rewarming (warm fluids, blankets, ECMO if severe). May need prolonged resuscitation. Defibrillation may fail below 30°C.

The T's

Tension Pneumothorax

Signs: Absent breath sounds unilateral, tracheal deviation, JVD, hypotension

Rx: Needle decompression (2nd ICS MCL or 4th/5th ICS AAL) → chest tube

Tamponade (Cardiac)

Signs: Beck's triad (JVD, hypotension, muffled heart sounds), PEA, narrow pulse pressure

Rx: Pericardiocentesis (subxiphoid approach, echo-guided), emergent thoracotomy

Toxins / Drug Overdose

Signs: Toxidromes, medication bottles, track marks, wide QRS (TCA), opioid pupils

Rx: Specific antidotes — Naloxone (opioid), NaHCO₃ (TCA), Flumazenil (benzo with caution), Digibind (digoxin), Lipid emulsion (local anesthetic toxicity)

Thrombosis — Coronary (MI)

Signs: Prior CP, ST changes, risk factors, known CAD

Rx: Emergent PCI (if available within protocol), fibrinolytics (if PCI unavailable in arrest → consider empiric tenecteplase)

Thrombosis — Pulmonary (PE)

Signs: Sudden PEA, prior DVT/immobility, RV dilation on echo, known hypercoagulable state

Rx: Systemic thrombolytics (alteplase 50 mg IV bolus in arrest), surgical embolectomy, ECMO. Continue CPR 60–90 min post-lytic.