BLS Algorithm

Basic Life Support - Foundation for All Resuscitation

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Basic Life Support (BLS) Algorithm

Key BLS Principle: Early Recognition & Action

Recognize cardiac arrest and activate emergency response immediately

Quality CPR and early defibrillation save lives

BLS Algorithm Components

BLS Assessment Sequence

Step 1: Scene Safety

  • Ensure scene is safe for you and the victim
  • Look for hazards: traffic, fire, electricity, violence
  • Use personal protective equipment if available
  • Move victim only if absolutely necessary

Step 2: Check Responsiveness

  • Adult/Child: Tap shoulders, shout "Are you okay?"
  • Infant: Tap foot, shout "Are you okay?"
  • Look for any movement or response
  • If responsive: stay with victim, call for help if needed
  • If unresponsive: proceed to next step

Step 3: Activate Emergency Response

  • Single rescuer: Call 911/emergency number first
  • Two rescuers: One calls 911, one starts CPR
  • Get AED/defibrillator if available
  • Return to victim immediately

Step 4: Check Breathing

  • Open airway using head-tilt chin-lift (adult/child) or jaw-thrust (trauma)
  • Look, listen, and feel for breathing (5-10 seconds)
  • Normal breathing: Regular, adequate chest rise
  • Abnormal breathing: Gasping, agonal respirations
  • If not breathing or only gasping: start CPR

CPR Sequence

Universal BLS Sequence: C-A-B

Compressions → Airway → Breathing

Exception: Newborn resuscitation uses A-B-C

Compressions

Compression Technique

  • Position: Center of chest, between nipples
  • Hands: Heel of one hand on other (adult/child)
  • Infant: Two fingers or two thumbs
  • Rate: 100-120 compressions per minute
  • Depth: At least 2 inches (5 cm) for adults
  • Allow full recoil between compressions

Quality Metrics

  • Rate: 100-120/min
  • Depth: 2+ inches (adults)
  • Recoil: Complete chest release
  • Interruptions: Minimize to <10 seconds
  • Switch: Every 2 minutes or when tired

Airway & Breathing

Airway Management

  • Head-tilt chin-lift: Standard maneuver
  • Jaw-thrust: For suspected trauma
  • Look for: Obstructions, foreign bodies
  • Remove: Visible objects only

Ventilation

  • Ratio: 30:2 (single rescuer)
  • Two rescuers: 15:2 (pediatric)
  • Each breath: 1 second, visible chest rise
  • Avoid: Hyperventilation

AED Use

AED Algorithm

  1. Power on AED and follow voice prompts
  2. Attach pads to bare chest (upper right, lower left)
  3. Analyze rhythm - don't touch victim
  4. If shock advised: Clear victim, deliver shock
  5. If no shock: Resume CPR immediately
  6. Continue 2 minutes of CPR between analyses

Age-Specific BLS Differences

Adult (≥8 years)

Compression Depth: 2+ inches (5 cm)

Hand Position: Heel of one hand on other

Compression Rate: 100-120/min

Ratio (1 rescuer): 30:2

Ratio (2 rescuers): 30:2

Child (1-8 years)

Compression Depth: 1/3 AP diameter

Hand Position: Heel of one or two hands

Compression Rate: 100-120/min

Ratio (1 rescuer): 30:2

Ratio (2 rescuers): 15:2

Infant (0-1 year)

Compression Depth: 1/3 AP diameter

Hand Position: Two fingers or two thumbs

Compression Rate: 100-120/min

Ratio (1 rescuer): 30:2

Ratio (2 rescuers): 15:2

Key Age-Specific Considerations

  • Infants: Most cardiac arrests are respiratory in origin
  • Children: Often have a pulse but inadequate perfusion
  • Adults: Usually primary cardiac arrest
  • All ages: Quality compressions are essential
  • Pediatric: Consider respiratory cause first

Timing Considerations

⏱️ 0-2 minutes: Begin CPR, attach AED
⏱️ 2-4 minutes: First rhythm analysis
⏱️ 4-6 minutes: Continue CPR, prepare for ALS
⏱️ Every 2 minutes: Rhythm check, switch compressors

BLS Key Principles

  • Early recognition and activation of emergency response
  • High-quality chest compressions (100-120/min, adequate depth)
  • Minimize interruptions in chest compressions
  • Early defibrillation with AED
  • Effective rescue breathing
  • Integration with advanced life support

Reference Information

Source: American Heart Association Guidelines for CPR and ECC

Last Updated: 2020 Guidelines

Note: BLS is the foundation for all resuscitation. Mastery of BLS is essential before learning ACLS or PALS.