Basic Life Support (BLS)

Overview

Step-by-Step BLS Sequence (Adults)

1. Scene Safety & Initial Recognition

• Verify the scene is safe.
• Tap the shoulders and shout: "Are you okay?"
• If unresponsive: look for absent or abnormal breathing (gasping counts as absent).
• Simultaneously check for a carotid/femoral pulse (no more than 10 seconds).

2. Activate Emergency Response

• Call 911 (or have a bystander call) and send someone for an AED.
• If alone with a phone, put it on speaker and begin CPR.
• Untrained bystanders can receive real-time CPR instruction from the EMS dispatcher.

3. Chest Compressions (the primary element)

4. Airway

• Head-tilt, chin-lift to open the airway.
• If trauma suspected, use jaw thrust first; if that fails or the airway cannot be opened, head-tilt-chin-lift is still appropriate (updated 2025 - do not withhold airway opening).
• Remove visible foreign bodies (no blind finger sweeps).

5. Breathing

• 30:2 ratio - give 2 rescue breaths after every 30 compressions (1 rescuer).
• Each breath delivered over ~1 second, with visible chest rise.
• Compression-only CPR (no breaths) is acceptable for untrained bystanders or when the rescuer is unwilling to provide rescue breaths - survival is comparable for witnessed cardiac arrest of cardiac cause.
• When an advanced airway is in place: continuous compressions at 100-120/min, ventilate every 5-6 seconds (10 breaths/min).

6. Defibrillation (AED)

• Attach and use an AED as soon as it arrives - analyze and shock if advised.
• Minimize hands-off time around the shock.
• Resume CPR immediately after the shock; reassess rhythm every 2 minutes.

Foreign Body Airway Obstruction (FBAO)

• Perform repeated cycles of 5 back blows (slaps between shoulder blades) followed by 5 abdominal thrusts (Heimlich) until the object is expelled or the person becomes unresponsive.
• The 2025 guideline now leads with back blows before abdominal thrusts - a new algorithm was added to reflect this.
• If the person becomes unconscious: begin CPR (30 compressions), look in the mouth before each breath, and remove any visible object.

Opioid Overdose (2025 New Recommendation)

• For adults and children in cardiac or respiratory arrest with suspected opioid overdose, it is reasonable to administer an opioid antagonist (e.g., naloxone), provided it does not delay or interrupt high-quality CPR.
• The BLS algorithm was updated to illustrate the role of naloxone in this setting.
• Patients treated for opioid overdose should receive naloxone and instructions on its use at discharge.

Special Populations

Obesity (2025 New)

• Use the same CPR technique as for patients without obesity. A 2024 ILCOR scoping review of 34 studies found no evidence to support technique modifications.

Pregnancy

• Position with left lateral tilt (to relieve aortocaval compression) or manually displace the uterus to the left.
• Prioritize high-quality CPR; perimortem caesarean section if ROSC not achieved promptly.

Post-Resuscitation (ROSC)

• Physical/rehabilitation needs
• Cognitive function
• Emotional/psychological health
• Family and caregiver support

BLS vs. ACLS

Key Concepts to Remember

1. Minimize interruptions - compression pauses >10 seconds worsen outcomes.
2. Full recoil between compressions allows ventricular filling.
3. Avoid hyperventilation - it increases intrathoracic pressure and reduces coronary perfusion.
4. C-A-B sequence - compressions first in adults/children; A-B-C is used if the arrest is likely respiratory in etiology (e.g., drowning, pediatric arrest).
5. Push hard, push fast, allow full recoil, minimize interruptions.