• Clinical science

Cardiopulmonary resuscitation


Cardiopulmonary resuscitation (CPR) is a lifesaving procedure that maintains circulation in patients with sudden cardiac arrest until cardiac function can be restored. Sudden cardiac arrest presents with unconsciousness, apnea, and pulselessness. There are two protocols for CPR: Basic Life Support (BLS) for lay rescuers and professionals alike and Advanced Cardiac Life Support (ACLS) for medical professionals. BLS includes checking the patient's responsiveness, calling for help, performing chest compressions and rescue breaths, and, if available, the use of an automated external defibrillator (AED). Advanced Cardiac Life Support includes additional procedures performed by medical professionals, such as drug therapy (especially epinephrine), securing the airways (e.g., endotracheal intubation), and finding and treating reversible causes of cardiac arrest. Immediate initiation of high-quality chest compressions is the most important factor in the success of CPR.


Chain of survival

  1. Check responsiveness and call for help
  2. Immediate cardiopulmonary resuscitation (CPR)
  3. Early defibrillation
  4. Early advanced life support

Immediate initiation of high-quality chest compressions, minimizing interruption of chest compressions, and early defibrillation are the most important factors in improving patient survival! Minimizing the time elapsed prior to CPR is crucial for avoiding long-term complications!

Basic Life Support (BLS)

What to do Details

Check responsiveness and call for help

  • Make sure the scene is safe
  • Check for responsiveness (e.g., verbally or by lightly shaking the shoulders)
  • Call for help and make a 911 emergency call
  • Send someone to get an AED
Check breathing
  • Clear airways by carefully tilting the head back/lifting the chin
  • Abnormal respiratory patterns include apnea, single breaths, or gasping. When in doubt, continue as if respiratory pattern is abnormal.

Cardiopulmonary resuscitation

  • 30 chest compressions followed by two rescue breaths (30:2)
    • Chest compression
      • Compression rate: 100–120 per minute
      • Compression depth: 5–6 cm (2–2.5 inches)
    • Rescue breathing
      • Verify sufficient ventilation by checking for thoracic movement during rescue breathing.
      • If psychological/hygienic factors prevent rescue breathing, perform continuous hands-only CPR.
  • Beginning early is essential!


  • Install AED (if available)
    • Positioning of the electric pads: Place one pad on the right chest (above the nipple) and the other on the left side of the thorax (below the nipple).
    • Administer shock if indicated
  • While the defibrillator is charging, CPR must continue!

CAUTION: Make sure that everyone stays clear of the patient before defibrillation!

Continue CPR Continue CPR until professional help arrives or the patient shows clear signs of life.

Early cardiac arrest often presents as gasping respiration, which should be interpreted as abnormal respiration and is therefore an indication for CPR!

Advanced Cardiac Life Support

Call for help
  • Shout
  • Activate hospital/institutional emergency response system
  • Professionals are allowed to check for carotid pulse for 10 seconds
Chest compressions
  • Perform chest compressions as described above in BLS.
  • Rescue breaths
  • Secure adequate oxygen supply
    • Artificial ventilation with 100% oxygen (e.g., bag valve mask)
    • Capnography to detect ROSC and monitor the effectiveness of CPR

Treat reversible causes

Return of spontaneous circulation (ROSC)

  • Diagnosis
    • Clear signs of life, e.g., breathing, coughing
    • Return of pulse and blood pressure
    • Increase in expiratory CO2 measured via capnography

All comatose patients who achieve ROSC (return of spontaneous circulation) after cardiac arrest should be subjected to mild hypothermia therapy for at least 24 hours (32–36°C target core temperature)!



Cardiac rhythm

Shockable rhythm Nonshockable rhythms
  • Arrhythmic and unsynchronized high-frequency fibrillation of the ventricles
  • Rapid, regular ventricular rate (along with pulselessness)
  • Rhythmic electrical activity (commonly low rate, wide, distorted QRS-complexes) and nonpalpable carotid pulse
  • Lack of ventricular electrical and mechanical activity
  • Myocardial contraction does not occur or does not generate sufficient cardiact output, which leads to electromechanical dissociation.


Special patient groups

Newborns and children

Ventilation is more important in children and newborns than in adults, as respiratory distress is a common cause of cardiac arrest in children!

  • Newborns
    • 5 initial rescue breaths → CPR
    • Compression rate: 100–120/min
    • Compression-to-ventilation ratio → 3:1
    • Technique of chest compressions: tip of two fingers (one emergency rescuer) or two-thumb-encircling hands (≥ 2 emergency rescuers)
  • Children older than 1 year
    • 5 initial rescue breaths → CPR
    • Compression rate: 100-120/min
    • Compression-to-ventilation ratio:
      • Medical professionals: 15:2
      • Lay rescuers: 30:2
    • Further management should follow the guidelines for adults.
  • Defibrillation: monophasic and biphasic waveforms: 2–4 J/kg of body weight