In 2010, international guidelines for cardiopulmonary resuscitation (CPR) recommended a change in compression depth. The minimum depth was raised from 38 to 50mm, although there was limited data to support the change from the 2005 guidelines.
Recently, the Resuscitation Outcomes Consortium (ROC) conducted a large scale study to examine patterns of CPR compression depth and associated survival rates.
The trial included 1,029 cases from 7 different sites across Canada and United States. The cases were typical of most cardiac events that take place out of a hospital; meaning 13 percent were in a public location and 40 percent were witnessed by a bystander.
The study was able to determine an average chest compression depth of 37.3mm, slightly less than recommended 2005 guidelines of 38mm and quite short of the new 50mm standard.
According to the study, half the patients received less than the 2005 guidelines and 90 percent received less than the 2010 guidelines; revealing a current trend of sub-optimal compression when delivering First Aid.
To lend credence to the “ sub-optimal trend,” the study has found a strong connection between survival and the increase in chest compression depth from 38 to 50mm.
Although compression depth continues to play an important role in CPR, the most effective depth is still unknown. The ROC found no evidence to prove or disprove the new recommendations at depths greater than 50mm.
During the study, the ROC also found an increased rate of chest compressions negated the positive effects of an increased depth. The recommend rate is 100 compressions per minute. Researchers suggest rescuers be cautious not to exceed a compression rate of 120.
The bottom line is that we don’t push hard enough on the chest. In order to increase survival rates, we need to deliver high-quality CPR. High-quality CPR must consist of proper compressions in both depth and rate; constraints rescuers need to be aware of.