What is the principle of Cardiopulmonary Resuscitation (CPR) as per the American Heart Association (AHA)?

Principles of CPR According to the American Heart Association (AHA)

The primary principle of CPR according to the AHA is to provide high-quality chest compressions with minimal interruptions to maximize oxygen and substrate delivery to vital tissues during cardiac arrest, thereby improving chances of survival with favorable neurological outcomes.

Core Components of High-Quality CPR

The AHA has identified five critical components that define high-quality CPR 1, 2:

1. Chest Compression Fraction (CCF)

   • Maintain CCF >80% (minimize interruptions)
   • CCF is the proportion of time chest compressions are performed during cardiac arrest
   • Lower CCF is associated with decreased ROSC and survival

2. Chest Compression Rate

   • Maintain 100-120 compressions per minute
   • Rates below this range reduce ROSC
   • Rates above this range may reduce coronary blood flow and decrease compression depth

3. Chest Compression Depth

   • Adults: At least 2 inches (5 cm)
   • Children: At least one-third the anterior-posterior dimension of the chest
   • Adequate depth ensures sufficient blood flow

4. Chest Recoil

   • Allow complete chest recoil after each compression
   • Avoid leaning on the chest between compressions
   • Complete recoil ensures adequate cardiac filling

5. Ventilation

   • Avoid excessive ventilation
   • For healthcare providers with advanced airway: 10 breaths/minute (1 breath every 6 seconds)
   • For lay rescuers: 30 compressions to 2 breaths ratio

Physiological Goal of CPR

The primary physiological goal of CPR is to maximize coronary perfusion pressure (CPP) during cardiac arrest 1. CPP is the difference between aortic diastolic and right atrial diastolic pressure during the relaxation phase of chest compressions and is the primary determinant of myocardial blood flow during CPR.

Basic Life Support Algorithm

The AHA recommends the following sequence for adult basic life support 1:

1. Check for responsiveness

   • Shout for nearby help
   • Activate emergency response system
   • Get AED and emergency equipment

2. Check for breathing and pulse simultaneously (within 10 seconds)

   • If no breathing or only gasping and no pulse, start CPR
   • If not breathing normally but has pulse, provide rescue breathing
   • If breathing normally with pulse, monitor until emergency responders arrive

3. Begin CPR

   • Start with chest compressions (C-A-B sequence rather than A-B-C)
   • Perform cycles of 30 compressions and 2 breaths
   • Use AED as soon as available

4. Continue CPR until

   • Advanced life support providers take over
   • The victim starts to move
   • Return of spontaneous circulation (ROSC)

Hands-Only CPR for Lay Rescuers

For untrained lay rescuers witnessing an adult sudden cardiac arrest, the AHA recommends Hands-Only CPR 1, 2:

• Activate emergency response system
• Provide high-quality chest compressions by pushing hard and fast in the middle of the victim's chest
• Continue until emergency services arrive

This approach is recommended because:

• It's easier for untrained rescuers to perform
• Can be more readily guided by dispatchers over the telephone
• Is as effective as conventional CPR for adults with witnessed arrest of cardiac origin

Monitoring CPR Quality

For healthcare providers, monitoring CPR quality is essential 1:

1. Real-time feedback devices - Help maintain proper rate and depth
2. End-tidal CO2 monitoring - When available, can indicate CPR quality
3. Invasive hemodynamic monitoring - When available, target CPP >20 mmHg or arterial diastolic pressure >25 mmHg

Common Pitfalls to Avoid

1. Excessive interruptions in chest compressions - Even brief pauses significantly reduce coronary and cerebral perfusion
2. Inadequate compression depth - Shallow compressions fail to generate sufficient blood flow
3. Improper compression rate - Too slow or too fast reduces effectiveness
4. Leaning on the chest - Prevents full chest recoil and reduces venous return
5. Excessive ventilation - Increases intrathoracic pressure and decreases venous return

Team-Based Approach

For healthcare providers, the AHA emphasizes a team-based approach where multiple tasks can be performed simultaneously by an integrated team of trained rescuers 1, 2. This includes:

• Building the team as members arrive
• Delegating roles clearly
• Performing tasks concurrently rather than sequentially
• Continuous quality improvement at provider, team, and systems levels

By adhering to these principles of high-quality CPR, rescuers can optimize outcomes for cardiac arrest victims and significantly improve chances of survival with good neurological function.