BLS C-A-B algorithm: Basic life support protocol

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Version control: Our ACLS, PALS & BLS courses follow 2020 American Heart Association Guidelines for CPR and ECC. American Heart Association guidelines are updated every five years. If you are reading this in January 2026 or later, please and we will update this page.

Compressions:

  • Compression rate of 100-120 per minute, pushing hard and fast in chest center.
  • Depth of 2" - 2.4” for adults (5-6cm).
  • Children and infants: 1/3 depth of the chest (2” and 1.5”).
  • Allow complete chest recoil between compressions and keep interruptions under 10 seconds.

Airway:

  • Head tilt/chin lift: tilt victim's head back and lift the victim's chin to open the airway.
  • Infant airway can be opened by placing the head in the “sniffing position.”

Breathing:

  • Give rescue breathing, mouth to mouth, in the apneic patient with a pulse.
  • In a pulseless patient without an advanced airway in place, provide chest compressions and breaths at a 30:2 ratio. For effective breathing, watch for chest rise and avoid excessive ventilation.
  • 10 BREATHS should be delivered each minute, or one breath every six seconds.
  • Each breath should be delivered over 1 second. Observe visible chest rise.
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How we reviewed this article

Our experts continually monitor the medical science space, and we update our articles when new information becomes available.

Current version
Dec 23, 2025

Reviewed by:

Changes: Clarified compression interruptions and breathing guidance
Mar 14, 2022