BLS Survey Components
The correct components of the Basic Life Support (BLS) survey are: Check for Responsiveness, Activate the Emergency Response System (EMS) and get an AED, assess Circulation (pulse check for healthcare providers), and Defibrillation when indicated.
The Sequential BLS Algorithm
According to the 2020 American Heart Association Guidelines, the BLS survey follows a specific sequence 1:
1. Scene Safety and Responsiveness
- First, verify scene safety
- Check for responsiveness by tapping the victim and shouting
- Shout for nearby help immediately
2. Activate Emergency Response System
- If the victim is unresponsive with no breathing or only gasping, immediately activate the emergency response system 2
- For a lone rescuer: activate via mobile device if appropriate
- For multiple rescuers: one stays with the patient while another activates EMS and retrieves the AED 1
3. Circulation Assessment
- Simultaneously check for breathing and pulse (healthcare providers only) 3
- Look for no breathing or only gasping while checking pulse
- Pulse check should take no more than 10 seconds 1
- If no pulse is felt, immediately start CPR
4. Defibrillation
- Retrieve and apply AED as soon as available 2
- Use the AED immediately when it arrives
- Check rhythm and deliver shock if indicated
- Resume CPR immediately after shock delivery
Key Algorithmic Decision Points
If pulse is present but no normal breathing:
- Provide rescue breathing (1 breath every 2-3 seconds or 20-30 breaths/minute)
- Recheck pulse every 2 minutes 1
If no pulse:
- Start CPR immediately with chest compressions
- Healthcare providers: 30 compressions to 2 breaths (single rescuer) or 15:2 (two rescuers for pediatrics) 1
- Continue until AED arrives or advanced providers take over
Critical Pitfalls to Avoid
Common mistake: Delaying CPR to search for a pulse. The 2010 guidelines emphasized de-emphasis of pulse checks for healthcare providers because delays in starting compressions worsen outcomes 2. If you're uncertain about a pulse within 10 seconds, start CPR.
Common mistake: Waiting too long to activate EMS. The emergency response system should be activated immediately upon recognizing unresponsiveness with abnormal breathing—don't wait to confirm cardiac arrest 3.
Common mistake: Delaying defibrillation. Rapid defibrillation is a powerful predictor of survival in VF cardiac arrest 2. The AED should be retrieved simultaneously with CPR initiation when multiple rescuers are available.
Team-Based Approach
In healthcare settings with multiple providers, these steps should occur simultaneously rather than sequentially 3:
- One rescuer checks responsiveness and pulse
- Another activates emergency response
- A third begins chest compressions
- A fourth retrieves and sets up the defibrillator
This choreographed approach minimizes time to first compression and defibrillation, which are the most critical determinants of survival 2.