In a study of two EMS agencies, researchers found an increase in the variability of chest compression quality for the rate and depth of compressions during the ground transport of cardiac arrest patients, according to a study presented in January at the 2010 National Association of EMS Physicians (NAEMSP) conference in Phoenix, Ariz.
Ben Bobrow, MD, medical director for the Arizona Department of Health Services, Bureau of Emergency Medical Services & Trauma System and the Maricopa Medical Center Resuscitation Science Center in Arizona, and colleagues examined data from automated external defibrillators (AEDs) from the Guardian Medical Transport in Flagstaff and the Mesa Fire Department in Mesa, both in Ariz., as part of a larger Resuscitation Quality Improvement Program.
The AEDs (E Series, Zoll Medical) contain an accelerometer to continuously record chest compression quality during resuscitation both at the scene and during ambulance transport. The device's built-in Real CPR Help, which provides real-time audiovisual feedback on the correct rate and depth of chest compressions, was inactivated, according to Bobrow.
The time during which the patient had spontaneous circulation was excluded from analysis as CPR would not have been required during those minutes. Variability was defined as the average of minute-by-minute standard deviations in depth or rate.
A total of 90 adult cardiac arrest events were electronically recorded, of which 45 included chest compressions both at the scene and in the ambulance. Variability in chest compression rate and chest compression depth was significantly greater during transport compared with at the scene. Absolute chest compression depth and chest compression rate tended to be lower during transport.
Although not reaching statistical significance, the percentage of chest compressions in compliance with American Heart Association 2005 guidelines for depth (1.5-2 in) and rate (100 compressions/minute) was nearly double at the scene compared with during transport, researchers reported.
They concluded that further investigation is needed to determine the causes of the increased variability along with the optimal timing and method of delivering manual chest compressions.
The study was awarded "Best EMS Professional Research Presentation" at the NAEMSP conference.