Compressions in CPR: Guidelines may need to dial back

Guidelines on chest compressions for cardiac arrest may be encouraging well-meaning aid to push too far. Out-of-hospital cardiac arrest patients had best outcomes with a chest compression depth between 40.3 and 55.3 mm, according to findings published online Sept. 24 in Circulation.

In 2010, the American Heart Association stated in guidelines that a minimum of 50 mm depth of compression was to be used, but provided no upper limit. Guidelines from 2005 suggested 38 to 50 mm depth compressions.

The findings of the research team led by Ian G. Stiell, MD, of the Department of Emergency Medicine and the Ottawa Hospital Research Institute at the University of Ottawa in Ontario, suggested that best practice might be higher than, but still closer to, 2005 guidelines than those published in 2010.  

The team assessed data collected by the Resuscitation Outcomes Consortium between June 2007 and December 2010 on 9,136 out-of-hospital cardiac arrest patients.

They found 31.3 percent of all patients had circulation return, 22.8 percent survived one day post-event and 7.3 percent survived to hospital discharge. Odds of survival to discharge were found to be 1.45 for patients who received compression within the best range. Those odds were further improved for the percentage of minutes compressions were performed in the target range. Stiell et al noted that survival peaked at 45.6 mm. This finding held regardless of sex.

An inverse correlation between depth and timing of compressions was seen: 53 percent of cases with greater than 120 compressions per minute also were among the shallower, generally less than 38 mm.

Still, better education is needed to provide better outcomes. Stiell et al noted that 40 percent of compressions were not within 2005 recommendation range.

While greater depth has better outcomes, optimally, Stiell et al wrote, the best outcomes are those that were within the 40.3 to 55.3 mm range and worked best at 45.6 mm. Stiell et al wrote that the 2010 target may be too high and they suggested that future guidelines and training be geared toward achieving a more optimal goal.