What are the primary steps and interventions in Advanced Cardiovascular Life Support (ACLS) for a patient in cardiac arrest?

Advanced Cardiovascular Life Support (ACLS) for Cardiac Arrest

High-quality CPR and early defibrillation are the only interventions proven to improve survival in cardiac arrest, and all other ACLS interventions must be built upon this foundation without compromising chest compression quality. 1

Immediate Recognition and Initial Actions

• Assess for pulse and responsiveness within 10 seconds; if no definite pulse is felt, immediately activate the emergency response system and begin CPR without delay 2, 3
• Attach a monitor/defibrillator immediately to identify the cardiac rhythm 1, 2
• Administer supplemental oxygen as soon as available 1, 3

High-Quality CPR: The Foundation

All ACLS interventions depend on maintaining excellent CPR quality throughout the resuscitation. 1, 2

• Push hard: at least 2 inches (5 cm) depth in adults 1, 2
• Push fast: 100-120 compressions per minute 1, 2, 3
• Allow complete chest recoil after each compression without leaning on the chest 1, 3
• Minimize interruptions in compressions to less than 10 seconds 1, 2
• Change compressor every 2 minutes or sooner if fatigued 1, 3
• Before advanced airway placement: use 30:2 compression-to-ventilation ratio 1, 3
• After advanced airway placement: provide continuous compressions with 1 breath every 6 seconds (10 breaths/min) 1, 3

Monitoring CPR Quality

• Use quantitative waveform capnography: if PETCO₂ <10 mm Hg, attempt to improve CPR quality 1
• If intra-arterial pressure monitoring available: relaxation phase (diastolic) pressure <20 mm Hg indicates need to improve CPR quality 1

Rhythm-Specific Management

Shockable Rhythms (VF/Pulseless VT)

Defibrillation is the definitive treatment for VF/pulseless VT and should be delivered with minimal interruption in compressions. 2, 3

• Deliver one shock immediately when VF/pulseless VT is identified 2, 3
• Resume CPR immediately after shock delivery for 2 minutes before checking rhythm 2, 3
• Do not delay defibrillation to establish IV access or administer medications 3
• Administer epinephrine 1 mg IV/IO every 3-5 minutes starting after the second shock 2, 3
• For shock-refractory VF/pulseless VT, consider either amiodarone (300 mg IV/IO bolus, then 150 mg) or lidocaine (1-1.5 mg/kg IV/IO, then 0.5-0.75 mg/kg) 1, 3

Important caveat: The 2018 AHA guidelines changed from favoring amiodarone to considering either amiodarone or lidocaine equally, as no antiarrhythmic drug has been shown to increase long-term survival or favorable neurological outcomes. 1 These medications may improve short-term outcomes like ROSC but not ultimate survival.

Non-Shockable Rhythms (PEA/Asystole)

• Administer epinephrine 1 mg IV/IO as soon as possible and repeat every 3-5 minutes 2, 3
• Continue high-quality CPR with rhythm checks every 2 minutes 2, 3
• Systematically search for and treat reversible causes (H's and T's) 3

Vascular Access and Medications

Epinephrine

• Administer 1 mg IV/IO every 3-5 minutes throughout the resuscitation for all cardiac arrest rhythms 2, 3, 4
• Establish intravenous or intraosseous access without delaying CPR 3
• Critical warning: Epinephrine can cause severe hypertension, cardiac arrhythmias, myocardial ischemia, and pulmonary edema, especially in patients with coronary artery disease 4

Calcium

Routine administration of calcium for treatment of cardiac arrest is not recommended. 1 This represents a key change in the 2023 guidelines, clarifying that calcium should only be used for specific indications (hyperkalemia, hypocalcemia, calcium channel blocker toxicity), not routinely.

Advanced Airway Management

• Initial ventilation should be provided with a bag-mask device using 30:2 compression-to-ventilation ratio 2, 3
• Consider endotracheal intubation or supraglottic advanced airway when appropriate, without prolonged interruptions in compressions 1, 2, 3
• Immediately confirm tube placement using waveform capnography or capnometry 1, 3
• Once advanced airway is secured, provide 1 breath every 6 seconds (10 breaths/min) with continuous chest compressions 1, 3
• Avoid excessive ventilation, which increases intrathoracic pressure and decreases cardiac output 1, 3

Recognition of Return of Spontaneous Circulation (ROSC)

Monitor for these signs during rhythm checks:

• Palpable pulse and measurable blood pressure 1
• Abrupt sustained increase in PETCO₂ (typically >40 mm Hg) 1
• Spontaneous arterial pressure waves with intra-arterial monitoring 1

Post-ROSC Care

All adults who do not follow commands after ROSC should receive treatment that includes a deliberate strategy for temperature control, regardless of arrest location or presenting rhythm. 1

• Maintain mean arterial pressure ≥65 mm Hg using vasopressors as needed 2, 3
• Target oxygen saturation 92-98% to avoid both hypoxemia and hyperoxemia 2, 3
• Obtain 12-lead ECG immediately 3
• Emergency coronary angiography is not recommended over a delayed or selective strategy unless the patient exhibits ST-segment elevation myocardial infarction, shock, electrical instability, signs of significant myocardial damage, or ongoing ischemia 1
• Select and maintain a constant temperature between 32°C and 37.5°C during post-arrest temperature control 1
• For patients with spontaneous hypothermia after ROSC who do not follow commands, do not routinely actively or passively rewarm faster than 0.5°C per hour 1

Reversible Causes (H's and T's)

Systematically evaluate and treat throughout resuscitation 3:

• Hypovolemia - administer fluid bolus, blood products
• Hypoxia - ensure adequate ventilation and oxygenation
• Hydrogen ion (acidosis) - optimize ventilation
• Hypo/hyperkalemia - check and correct electrolytes
• Hypothermia - rewarm appropriately
• Tension pneumothorax - needle decompression
• Tamponade (cardiac) - bedside echocardiography, pericardiocentesis
• Toxins - consider antidotes
• Thrombosis (pulmonary) - consider thrombolytics
• Thrombosis (coronary) - consider coronary angiography

Critical Pitfalls to Avoid

• Adherence to protocol is essential: A 2020 study demonstrated that the probability of obtaining ROSC was 96% with 0-2 deviations from ACLS protocol, 59% with 2-5 deviations, and only 11% with >6 deviations per event 5
• Do not interrupt compressions for prolonged periods - pauses should be <10 seconds only for rhythm checks, shock delivery, pulse checks with organized rhythm, or advanced airway placement 1
• Avoid excessive ventilation - this is a common error that decreases cardiac output 1, 3
• Do not routinely continue antiarrhythmic medications after ROSC - there is insufficient evidence to support this practice 1