Chest Compressions Save Lives
 

Reported September 17, 2009

(Ivanhoe Newswire) – The most important thing you can do for someone who experiences cardiac arrest is chest compressions – even as you wait for emergency medical services personnel to arrive. First responders doing cardiopulmonary resuscitation (CPR) who spend more time giving chest compressions dramatically increase the chance for a person in cardiac arrest to survive, according to a new study.

"Chest compressions move blood with oxygen to the heart and the brain to save the brain and prepare the heart to start up its own rhythm when a shock is delivered with a defibrillator," Jim Christenson, M.D., lead author of the study and clinical professor of emergency medicine at the University of British Columbia, was quoted as saying. "We found that even short pauses in chest compressions were quite detrimental."

The proportion of time during CPR that rescuers spend giving chest compressions during each minute of CPR, called the chest compression fraction (CCF), is extremely variable. Prior to 2005, interruptions to chest compressions resulted in less than 50 percent of total CPR time being spent on chest compressions.

The 2005 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care were revised to emphasize the importance of minimizing interruptions in chest compressions. This resulted in some emergency medical services (EMS) agencies achieving a CCF between 60 percent and 85 percent, Christenson said.

Researchers analyzed data from 78 EMS agencies in seven locations that were part of the Resuscitation Outcomes Consortium (ROC), a group of 11 regional clinical centers in Canada and the U.S. that study promising out-of-hospital therapies for cardiac arrest and traumatic injury. Automated external defibrillators measured the presence and frequency of chest compressions for each patient.

Between December 2005 and March 2007, researchers studied patients who had a ventricular fibrillation or pulse-less ventricular tachycardia cardiac arrest prior to EMS arrival. Ventricular fibrillation or pulse-less ventricular tachycardia are abnormal heart rhythms in which the heart's lower chambers contract erratically or extremely rapidly and pump little or no blood.

In the 506 cases analyzed, researchers found that a return to spontaneous circulation was achieved 58 percent of the time when the CCF was zero to 20 percent; that figure rose to 79 percent when the CCF was 81 to 100 percent.

Survival to hospital discharge occurred in 12 percent of patients when CCF was zero to 20 percent. It increased to nearly 29 percent when CCF was 61 to 81 percent, but dropped slightly to 25 percent when CCF was 81 to 100 percent.
Researchers said the slight drop in survival in the group with the highest CCF rate was likely due to the small sample size of the study, although they acknowledge the possibility of a plateau effect when CCF is above 80 percent.

"There was roughly a 10 percent increase in the chance of survival for every 10 percent increase in the chest compression fraction," Christenson said. He stated that more study is needed to identify the ideal CCF and to show when compressions are the most important, such as immediately before or after delivery of a shock.

"We should continue chest compressions as much as possible, only pausing to do things that are proven to be medically beneficial," said Christenson.

For bystanders, the results emphasize the lifesaving potential of learning CPR and delivering chest compressions. "The chest compressions you do on a loved one are one of the most important things that can be done," said Christenson. "If you feel rusty or are not confident giving mouth-to-mouth ventilation along with chest compressions then just do chest compressions. Even by themselves, chest compressions can make a difference."

SOURCE: Circulation: Journal of the American Heart Association, September 14, 2009