By the Blouin News Science & Health staff

CPR quality varies, impacts survival rates

by in Medicine.

People learn CPR at a service summit on the National Mall January 19, 2013 in Washington, DC. Events around the Inauguration started with a national day of service a yearly event where Americans are encouraged to volunteer and contribute to service projects to honor American civil rights leader Martin Luther King.  AFP PHOTO/Brendan SMIALOWSKI        (Photo credit should read BRENDAN SMIALOWSKI/AFP/Getty Images)

People learn CPR at a service summit in Washington, D.C. AFP/Getty Images/Brendan Smialowski

CPR can be a life-saving technique when performed correctly, but according to a recent statement from the American Heart Association, the quality of CPR varies widely among hospitals and EMS departments. The inconsistency suggests that many deaths from cardiac arrest may be preventable, and indicates the need for better training in CPR administration, the researchers said.

Every year, more than 500,000 children and adults in the United States experience cardiac arrest. The chance of survival differs depending on where the episode occurs — if it happens outside of a hospital, survival rates range from 3 to 16%; inside a hospital, rates range from 12 to 22%. While CPR is considered an essential part of resuscitation efforts after cardiac arrest, it is an inefficient procedure. Even under optimal conditions, CPR provides only 10 to 30% of normal blood flow to the heart, and 30 to 40% of the normal flow to the brain. If the technique is to be effective, the researchers wrote, it is therefore imperative that rescue workers deliver the highest-quality CPR possible.

CPR consists of five main components: chest compression fraction (CCF), chest compression rate, chest compression depth, ventilation, and chest recoil. When using proper CPR technique, rescue workers should deliver between 100 and 120 compressions per minute at a depth greater than or equal to two inches for adults, giving between six and 12 breaths per minute. CCF, the proportion of time that chest compressions are performed during a cardiac arrest, should be greater than 80%.

Previous research has shown that the quality of CPR can impact the patient’s chances of survival. According to a 2012 study, for instance, when rescue workers don’t compress the chest far enough, survival-to-discharge rates decrease by 30%. Another study from 2005 found that when rescuers compress the chest too slowly, the chance that the patient’s circulation will spontaneously return drops from 72% to 42%. Furthermore, researchers have found that a majority of rescue workers lean over the patient’s chest during CPR, which prevents the chest from recoiling fully and decreases the blood flow throughout the heart.

Monitoring both the patient’s response and the rescue worker’s performance, and using that information to provide the worker with real-time feedback can correct basic mistakes in CPR. Studies from 2010 and 2012 have also shown that appointing a team leader who directs and coordinates all aspects of the resuscitation can greatly improve CPR quality. In addition to enhanced training for rescue workers, the AHA called for standardized CPR performance metrics, as well as more research on the interactions between the individual components of CPR and the impact of healthcare provider characteristics, fatigue, and work and training environments on CPR quality.