What are the proper Basic Life Support (BLS) steps for an unresponsive adult or child, including assessment, chest compressions, ventilation, and AED use?

Basic Life Support (BLS) for Unresponsive Adults and Children

For an unresponsive adult or child, immediately verify scene safety, check responsiveness while simultaneously assessing for normal breathing and pulse (within 10 seconds), activate emergency services, and begin high-quality CPR with 30 compressions followed by 2 breaths, using an AED as soon as available. 1, 2

Initial Assessment and Activation

Scene Safety and Responsiveness Check:

• First, ensure the scene is safe for you and the victim 1
• Check for responsiveness by shouting and tapping the victim
• Simultaneously look for absent or abnormal breathing (only gasping) AND check for a pulse—you have 10 seconds maximum for this assessment 3, 1

Activation Sequence:

• Lone rescuer with adult: Activate emergency response system FIRST (call 911), then immediately begin CPR 1
• Lone rescuer with child/infant: If you have a cell phone, call 911 and start CPR; if no cell phone, perform 5 cycles of CPR (about 2 minutes) before leaving to call 911 3
• Multiple rescuers: First rescuer stays with victim while second rescuer activates emergency services and retrieves AED 3, 2

High-Quality Chest Compressions

Positioning and Technique:

• Place the victim's torso at approximately the level of your knees 1
• Position yourself with arms extended, elbows locked, shoulders directly perpendicular over the victim's chest 4
• Place heel of palm on the lower half of the sternum (center of chest) 3, 4

Compression Specifications:

For Adults:

• Depth: 2-2.4 inches (5-6 cm), avoiding exceeding 6 cm 4, 5
• Rate: 100-120 compressions per minute 3, 4
• Technique: 2 hands for adults 1

For Children:

• Depth: At least one-third anteroposterior diameter of chest, approximately 2 inches 3
• Rate: 100-120 compressions per minute 3
• Technique: 1 or 2 hands (either is reasonable) 3

For Infants:

• Depth: At least one-third anteroposterior diameter of chest, approximately 1.5 inches 3
• Technique: 2 fingers for single rescuer; 2-thumb encircling technique for 2 rescuers 3, 6
• If unable to achieve adequate depth with 2 fingers, use heel of 1 hand 3, 6

Critical Quality Elements:

• Allow complete chest recoil after each compression 3, 4
• Minimize interruptions in compressions 3
• Change compressor every 2 minutes or sooner if fatigued 3

Ventilation

Compression-to-Ventilation Ratios:

• Single rescuer (all ages): 30 compressions : 2 breaths 3, 1, 2
• Two rescuers with child/infant: 15 compressions : 2 breaths 3, 2
• Two rescuers with adult: 30 compressions : 2 breaths 1

Ventilation Technique:

• Deliver each breath over 1 second 1
• Give enough tidal volume to produce visible chest rise (400-600 mL) 4, 7
• Avoid hypo- and hyperventilation 1
• For adults: 1 breath every 6 seconds (10 breaths/minute) if pulse present but no breathing 1
• For children: 1 breath every 2-3 seconds (20-30 breaths/minute) if pulse present but no breathing 3

Important Caveat: Healthcare professionals should perform both compressions and ventilations for all cardiac arrest patients, regardless of cardiac or noncardiac cause 1. Compression-only CPR is acceptable for lay rescuers unwilling or unable to provide ventilations 7.

AED Use

Timing and Application:

• Use AED as soon as it arrives—do not delay 3, 2
• For witnessed sudden collapse in children, retrieve AED immediately after activating emergency services 3
• For unwitnessed collapse when alone, perform 2 minutes of CPR before retrieving AED if necessary 3

AED Protocol:

1. Turn on AED and follow voice prompts 2
2. Apply pads to bare chest (use pediatric pads for children/infants if available; adult pads acceptable if pediatric unavailable, ensuring pads don't touch each other) 2
3. Ensure no one is touching victim during rhythm analysis
4. If shockable rhythm: Deliver 1 shock, then immediately resume CPR for 2 minutes before next rhythm check 3
5. If non-shockable rhythm: Immediately resume CPR for 2 minutes 3

Special Considerations

Pulse Present but No Normal Breathing:

• Provide rescue breathing only (no compressions) 3
• Check pulse every 2 minutes 3
• If heart rate <60/min with signs of poor perfusion in children: Start CPR 3

Firm Surface:

• Perform compressions on a firm surface when possible 3
• In hospital settings, activate bed's "CPR mode" to increase mattress stiffness 3
• Use backboard in hospital to improve compression depth 3

Continue CPR Until:

• Advanced life support providers take over
• The victim starts to move/regains consciousness
• You are physically unable to continue 3, 2

Common Pitfall: Do not check for pulse or stop compressions unless the AED prompts you to do so, the victim moves, or help arrives. Unnecessary interruptions in chest compressions significantly reduce survival 3.