The apparatus has a pressure pad configured to be applied to a chest near or at a location where a rescuer applies force to produce a chest compression. A processing circuit processes an output of a sensor to determine whether the rescuer releases the chest following chest compression. A prompting unit provides the rescuer with information as to whether the chest is being released following chest compression. Independent claims are also included for the following: (a) a method of determining chest compression during CPR (b) a method of analyzing ECG signals during application of CPR.
