What is the recommended CPR (Cardiopulmonary Resuscitation) protocol for cardiac arrest?

CPR Protocol for Cardiac Arrest

Immediately begin high-quality chest compressions at a depth of at least 2 inches (5 cm) at a rate of 100-120 compressions per minute with a 30:2 compression-to-ventilation ratio, activate emergency services, and apply an AED as soon as available. 1

Initial Recognition and Activation

For lay rescuers:

• Check for responsiveness by shouting and tapping the patient 1
• Assess for absent or abnormal breathing (including gasping, which is present in 40-60% of cardiac arrests and often misinterpreted) 1
• If unresponsive with absent or abnormal breathing, assume cardiac arrest and immediately call for help 1
• Activate emergency response system first via mobile phone on speaker, then immediately begin CPR 1
• Send someone to retrieve an AED and emergency equipment 1

For healthcare providers:

• Check responsiveness and simultaneously assess breathing and pulse within 10 seconds 1, 2
• If no definitive pulse is felt within 10 seconds, start compressions immediately (healthcare providers often take too long and have difficulty determining pulse presence) 1
• Activate emergency response and retrieve AED/emergency equipment 1

High-Quality Chest Compressions (The Critical Component)

Compression technique:

• Position hands on the lower half of the sternum 1
• Push hard with depth of at least 2 inches (5 cm), but avoid excessive depth greater than 2.4 inches (6 cm) 1, 2
• Maintain rate of 100-120 compressions per minute 1, 2
• Allow complete chest recoil between compressions without leaning on the chest 1, 2
• Minimize interruptions to less than 10 seconds 1, 2
• Change compressor every 2 minutes or sooner if fatigued 1, 2, 3
• Target chest compression fraction of at least 60% 1

Common pitfall: Compressions are often too shallow and interrupted too frequently. The compressor's body weight should be centered directly over the mid-sternum to achieve adequate depth. 4

Compression-to-Ventilation Ratio

For lay rescuers:

• Untrained or unwilling rescuers should provide compression-only CPR 1
• Trained rescuers should provide 30 compressions followed by 2 breaths 1, 2

For healthcare providers:

• Deliver 30 compressions followed by 2 breaths 1
• Each breath should be delivered over 1 second with sufficient volume to achieve visible chest rise 2
• Avoid excessive ventilation, which increases intrathoracic pressure and decreases cardiac output 1, 2
• Pause compressions for less than 10 seconds to deliver the 2 breaths 1

AED/Defibrillation Protocol

Immediate defibrillation sequence:

• Apply AED as soon as it becomes available 1, 2, 3
• Check rhythm after 2 minutes of CPR 1, 2
• For shockable rhythms (VF/pulseless VT): deliver one shock immediately 1, 3
• Resume CPR immediately for 2 minutes after shock delivery without checking rhythm or pulse 1, 5
• Do not delay defibrillation to establish IV access or administer medications 2

Shock energy:

• Biphasic: 120-200 Joules initially (manufacturer recommendation), use maximum available if unknown; subsequent doses equivalent or higher 1
• Monophasic: 360 Joules 1

Critical evidence: Post-shock data shows the majority of patients remain pulseless for over 2 minutes after defibrillation, with 25% remaining pulseless beyond 120 seconds, strongly supporting immediate resumption of compressions rather than pulse checks. 5

Advanced Life Support Medications

Vascular access and epinephrine:

• Establish IV or IO access as soon as feasible 1, 2, 3
• Administer epinephrine 1 mg IV/IO every 3-5 minutes for all cardiac arrest rhythms 1, 2, 3
• Continue throughout resuscitation until ROSC 2

Antiarrhythmics for refractory VF/pulseless VT:

• Amiodarone: 300 mg IV/IO bolus first dose, 150 mg second dose 1, 2, 3
• Lidocaine (alternative): 1-1.5 mg/kg IV/IO first dose, 0.5-0.75 mg/kg second dose 1, 2

Advanced Airway Management

Airway placement timing:

• Place endotracheal tube or supraglottic airway only after initial CPR cycle with defibrillation (if appropriate) or after ROSC 6
• Minimize interruptions in compressions during placement 6
• Confirm placement immediately with waveform capnography or capnometry 1, 2, 3

Ventilation with advanced airway:

• Once secured, provide 1 breath every 6 seconds (10 breaths per minute) 1, 2, 3
• Continue chest compressions continuously without pausing for breaths 1, 2
• Use manual ventilation devices (bag-valve-mask, Bain's circuit) rather than mechanical ventilators, as modern ventilators erroneously sense chest compressions as spontaneous triggers and deliver excessive respiratory rates 7

Critical pitfall: If a patient on mechanical ventilation develops cardiac arrest, immediately disconnect from the ventilator and switch to manual ventilation. 7

Rhythm Assessment Cycles

• Check cardiac rhythm every 2 minutes 1
• Do not check rhythm immediately after defibrillation 1
• Minimize interruptions during rhythm checks 1
• Continue CPR until advanced life support providers arrive or victim shows signs of movement 1

Reversible Causes (H's and T's)

Systematically evaluate and treat throughout resuscitation: 1, 2

• Hypovolemia - administer IV fluids
• Hypoxia - ensure adequate oxygenation
• Hydrogen ion (acidosis) - adequate ventilation
• Hypo/hyperkalemia - check and correct electrolytes
• Hypothermia - rewarm if accidental
• Tension pneumothorax - needle decompression
• Tamponade (cardiac) - pericardiocentesis
• Toxins - specific antidotes
• Thrombosis (pulmonary) - thrombolytics/mechanical intervention
• Thrombosis (coronary) - evaluate for acute coronary syndrome

Recognition of ROSC

Stop CPR and assess for: 1, 8

• Palpable pulse and blood pressure
• Abrupt sustained increase in PETCO₂ (typically ≥40 mmHg)
• Spontaneous arterial pressure waves with intra-arterial monitoring

Post-ROSC Care

Immediate management:

• Maintain mean arterial pressure ≥65 mmHg with vasopressors 2, 8, 3
• Target oxygen saturation 92-98% (avoid both hypoxemia and hyperoxemia) 2, 8
• Obtain 12-lead ECG immediately to identify ST-elevation MI 2, 8
• Consider urgent coronary angiography for suspected cardiac etiology 2, 8
• Initiate targeted temperature management for patients not following commands 2, 8, 3

Key principle: The risk of harm from performing CPR on someone not in cardiac arrest is extremely low (8.7% chest pain, 1.7% rib/clavicle fracture, 0.3% rhabdomyolysis, no visceral injuries), so when in doubt, start CPR. 1