Bls guidelines
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AHA BLS guidelines 2025 2026 basic life support CPR updates
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Basic Life Support (BLS) Guidelines
Based on current American Heart Association (AHA) guidelines, as referenced in Braunwald's Heart Disease, Tintinalli's Emergency Medicine, and Fuster & Hurst's The Heart.
The Chain of Survival
BLS is the first link in the chain of survival for sudden cardiac arrest (SCA). For each minute that a shock is delayed, survival falls by 10-12%. Survival to discharge for in-hospital cardiac arrest is 33% when CPR starts within 1 minute vs. 14% when delayed beyond 1 minute.
Sequence of Steps: C-A-B (not A-B-C)
Since 2010, the AHA changed the BLS sequence from A-B-C (Airway-Breathing-Circulation) to C-A-B (Compressions-Airway-Breathing) to minimize delays to chest compressions and avoid excessive ventilation.
| Step | Action |
|---|---|
| 1 | Scene safety - verify environment is safe before approaching |
| 2 | Check responsiveness - tap shoulders, shout |
| 3 | Call for help - activate EMS (911), send for AED |
| 4 | Assess pulse and breathing - <10 seconds; lay rescuers skip pulse check (risk of false positive) |
| 5 | Begin chest compressions immediately if no pulse or no normal breathing |
| 6 | Attach AED as soon as available, analyze rhythm, shock if indicated |
| 7 | Open airway - head tilt-chin lift (or jaw thrust if trauma suspected) |
| 8 | Give rescue breaths (trained rescuers) |
Chest Compressions - Key Parameters
| Parameter | Recommendation |
|---|---|
| Rate | 100-120 compressions/minute |
| Depth (adults) | 5-6 cm (2-2.5 inches); not more than 6 cm |
| Depth (children) | At least 1/3 AP chest diameter (~5 cm) |
| Depth (infants) | At least 1/3 AP chest diameter (~4 cm) |
| Recoil | Allow complete chest recoil between compressions; do not lean on chest |
| Interruptions | Minimize; no pause longer than 10 seconds; target compression fraction >60% |
| Rescuer switch | Switch compressors every 2 minutes to prevent fatigue |
Hand position: Heel of one hand over the lower half of the sternum; other hand on top; arms straight at elbows.
Compression:Ventilation Ratio
| Setting | Ratio |
|---|---|
| Adult (1 or 2 rescuers) | 30:2 |
| Children/infants - 1 rescuer | 30:2 |
| Children/infants - 2 rescuers | 15:2 |
| Lay rescuers (untrained) | Compression-only CPR (hands-only) - at least as effective as conventional CPR |
| Advanced airway in place | Continuous compressions at 100-120/min; 1 breath every 6 seconds (10 breaths/min) |
AED Use
- Apply an AED as soon as it is available - do not delay for CPR first in unmonitored/unwitnessed arrest
- Analyze rhythm; shock VF/pulseless VT immediately
- Resume CPR immediately after shock (Class IIb) rather than waiting to recheck rhythm
- Continue CPR except when AED is analyzing or delivering a shock
Airway Management
- Head tilt-chin lift: standard maneuver; displace tongue/epiglottis from oropharynx
- Jaw thrust: use if cervical spine injury suspected (does not extend neck)
- Rescue breaths: each breath delivered over 1 second; enough to produce visible chest rise
- Do not perform blind finger sweeps (risk of pushing foreign body deeper)
- Remove only visible foreign bodies
Special Populations
Infants (< 1 year):
- 2-finger compressions just below the inframammary line
- Rate: 100-120/min
- Choking: alternate 5 back blows + 5 chest thrusts (NOT Heimlich maneuver)
Children (1 year to puberty):
- 1 or 2-hand compressions; 2-rescuer ratio is 15:2
- Choking (conscious): Heimlich maneuver (abdominal thrusts)
- Choking (unconscious): begin chest compressions; look for foreign body before each rescue breath
Pregnant patients: Left lateral uterine displacement during CPR; prioritize maternal resuscitation.
When to Discontinue BLS
BLS termination can be guided by the Ontario BLS Termination Rule (3 criteria):
- Unwitnessed arrest
- Three rounds of CPR + AED analysis without ROSC
- No AED shock delivered
All three criteria must be met to consider termination.
Special Situations
- Opioid emergency: Naloxone can be given for suspected life-threatening opioid-associated emergencies alongside CPR
- Precordial thump: Optional only when pulseless VF/VT witnessed without a defibrillator immediately available; not routinely recommended
- Compression-only CPR: Advised for lay/untrained rescuers; also appropriate during infectious disease concerns (e.g., pandemic setting)
Sources: Tintinalli's Emergency Medicine, Ch. 22 | Braunwald's Heart Disease, 15e | Fuster & Hurst's The Heart, 15e | Goldman-Cecil Medicine
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