Basic Life Support (BLS): Adult Resuscitation

Updated: May 10, 2018
  • Author: James J Lamberg, DO; Chief Editor: Meda Raghavendra (Raghu), MD  more...
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Basic Life Support (BLS): Adult Algorithm

Basic Life Support: Adult Arrest

1. Verify scene safety. [1, 2, 3]

2. Check responsiveness; if none, follow steps below:

  • Shout for nearby help.
  • Activate emergency response system (eg, facility protocol, mobile phone).
  • If alone, leave the victim to activate the emergency response system and get the AED before CPR.
  • Get automated external defibrillator (AED) and emergency equipment or send someone to do so.
  • Assess for breathing or only gasping.

3. Assess for no breathing or only gasping and check pulse for less than 10 seconds, simultaneously. If normal breathing and pulse definitely present, monitor until additional help arrives.

4. If no normal breathing but pulse present, follow the steps below:

  • Provide rescue breathing: 1 breath every 5-6 seconds.
  • Activate emergency response system (if not already done) after 2 minutes.
  • Continue rescue breathing with pulse check every 2 minutes; if no pulse, begin CPR.
  • If possible opioid overdose, administer naloxone, if available, per protocol.

5. If no breathing (or only gasping) and no pulse, follow the steps below:

  • Start high-quality cardiopulmonary resuscitation (CPR) at a compressions-to-breaths ratio of 30:2.
  • Every 2 minutes, check pulse, check rhythm, and switch compressors.
  • Use AED as soon as available; if shockable rhythm, defibrillate and then immediately start CPR.
  • High-quality CPR and changing rescuers every 2 minutes improves a victim’s chance of survival.

6. With AED attached, assess for shockable rhythm, as follows:

  • If shockable, defibrillate and then immediately start CPR for about 2 minutes.
  • If nonshockable, resume CPR for about 2 minutes and reassess for pulse and shockable rhythm.


See the list below:

  • Check pulse at carotid artery.
  • Compression landmarks: lower half of sternum between the nipples
  • Compression method: heel of one hand, other hand on top
  • Depth: at least 2 in (5 cm); attempt to avoid excessive depth (2.4 in [6 cm])
  • Allow complete chest recoil after each compression.
  • Compression rate: 100-120 compressions per minute
  • Compression-to-ventilations ratio: 30:2, for one or two rescuers
  • Continuous compressions if advanced airway present
  • Rotate compressor every 2 minutes or if fatigued.
  • Minimize interruptions in compressions to less than 10 seconds.
  • Avoid excessive ventilation.
  • If end-tidal carbon dioxide tension (PETCO 2) is less than 10 mm Hg, attempt to improve CPR quality. [4]


See the list below:

  • Head tilted, chin lifted
  • Jaw thrust if trauma suspected


See the list below:

  • Ventilation with advanced airway every 6 seconds, asynchronous with compressions
  • Rescue breathing every 5-6 seconds
  • Deliver at about 1 second/breath.
  • Watch for visible chest rise.


See the list below:

  • Attach and use AED as soon as available.
  • Minimize interruptions in chest compressions before and after shock.
  • Resume CPR beginning with compressions immediately after each shock.

Most Recent Guideline Changes

Changes from the 2010 guidelines include the following:

  • Simultaneous breathing and pulse check in less than 10 seconds
  • Administer epinephrine as soon as feasible after the onset of cardiac arrest due to an initial nonshockable rhythm.
  • Provide opioid overdose education, either alone or coupled with naloxone distribution and training, to persons at risk for opioid overdose.
  • In pregnancy, if the fundus height is at or above the level of the umbilicus, manual left uterine displacement can be beneficial in relieving aortocaval compression during chest compression.