Why Proper Chest Compressions are So Important

Survival rates from sudden cardiac arrest are very low, less than 10% on average in the US. 1 Itís a grim fact that most sudden cardiac arrest victims will not live. Recently, researchers have found that proper chest compressions play an even more important role in improving survival from sudden cardiac arrest.

The findings are reflected in the 2010 CPR and ECC Guidelines which now emphasize "high-quality CPR." You should be aware that there is a new focus on maintaining proper compression depth and rate and reducing interruptions in compressions. Three key points of high-quality CPR are:

  • Do chest compressions hard (at least 2 in/5 cm depth)
  • Do chest compressions fast (at least 100/min)
  • Minimize interruptions in compressions

What Happens During CPR
Letís review the purpose of CPR. By pushing in the middle of the chest, you can circulate oxygenated blood through the body of someone in cardiac arrest. This keeps the brain and other organs alive until the heart can be re-started with a defibrillator. Chest compressions can help delay tissue death in vital organs for a short time; however, it doesnít do much good if compressions are not performed properly.

There is some debate about the exact mechanisms that occur during chest compressions. We do know the force increases pressure in the heart and chest. This pressure is called coronary perfusion pressure or CPP.

Researchers have studied rescuers doing chest compressions and found they tend to not push hard enough or fast enough. 2 They have documented that rescuers push less than 1.5 inches up to 70% of the time. The recommended depth is 2 inches. Thus CCP is too low for the chest compressions to produce adequate blood flow.

Compression Depth
Compression depth is one of the main factors in high-quality CPR. We know that pushing hard enough on the chest greatly affects survival rates. In addition, defibrillation success is associated with increased compression depth. It also prolongs the time when a fibrillating heart is receptive to defibrillation. Remember that letting the chest to fully recoil during compressions allows the heart to more fully refill with blood.

Comps

Interruptions in CPR
If you stop chest compressions only for a short time the CPP goes down considerably. It takes about a minute of chest compressions to build up enough CPP to circulate blood effectively.3 To keep CPP up the 2010 Guidelines recommends minimizing interruptions in chest compressions.

What You Need to Do
What does high-quality CPR mean to you? You must push hard and fast on the chest: a compression rate of AT LEAST 100/min and a consistent depth of AT LEAST two inches. Thatís a lot of pushing so keep in mind it is good to switch rescuers every 2 minutes of CPR if possible because itís difficult for any rescuer to proper do compressions for more than two minutes.

Lastly, don't stop chest compressions unless absolutely necessary. It is okay to stop them when an AED is analyzing or shocking, but try to keep compressions going at all other times. Even short pauses cause the pressure in the chest to go down significantly.

Summary
More than ever before, we know CPR and chest compressions are important. Next time you are practicing CPR, think about achieving high-quality CPR. Chest compressions can keep someone alive, but they must be done correctlyódo them hard and fast.

References

1. Eisenberg MS. Resuscitate: How Your Community Can Improve Survival from Sudden Cardiac Arrest. Seattle: U. of Washington Press; 2009.

2. Abella BS, Alvarado JP, Myklebust H, Edelson DP, Barry A, OíHearn N, Vanden Hoek TL, Becker LB. Quality of Cardiopulmonary Resuscitation During In-Hospital Cardiac Arrest. JAMA. 2005;293(3):305-310.

3. Yu T, Weil MH, Tang W, Sun S, Klouche K, Povoas H, Bisera J. Adverse outcomes of interrupted precordial compression during automated defibrillation. Circulation. 2002 Jul 16;106(3):368-72.