Chest wall acceleration and force measurements in simulated manual and mechanical cardiopulmonary resuscitation

During CPR, the dynamics of the chest compression process play a major role in determining the outcome of the resuscitation effort. To quantify chest wall motion during CPR, a number of important variables must be determined, including maximum downward acceleration and velocity of the chest wall, time during which the wall is held in compression, and maximum depth and rate of chest compression. In this study, miniature accelerometers were used to record chest wall motion during simulated CPR with standard training manikins. One series of CPR tests included force measurements from a three-dimensional force platform placed under the manikin. The results of this investigation showed that American Heart Association (AHA)-certified rescuers are able to produce a consistent pattern of chest wall displacement during a manikin training exercise, and only small differences in displacement recordings are found when comparing one certified rescuer to another. Any given rescuer will usually generate a consistently repeatable acceleration pattern during CPR. However, these cyclical acceleration patterns differ markedly when comparing different certified rescuers. Mechanical CPR with a standard device produced larger peak accelerations than manual CPR. However, the maximum downward velocity was usually higher with manual CPR. In comparison with trained but clinically inexperienced individuals, rescuers with extensive in hospital experience produced relatively larger downward accelerations, longer "hold" times with the chest in compression, and maximum chest displacements that exceeded the current AHA recommendations. Measurements of the force transmitted through the manikin to a force platform clearly indicated the presence of a "hold" phase (if present) and the existence of large force components in the horizontal plane.