systems and methods related to the field of cardiac resuscitation , and in particular to devices for assisting rescuers in performing cardio - pulmonary resuscitation are described herein . in some aspects , the system includes a chest compression sensor providing movement information during a plurality of manual chest compressions performed by a rescuer on a chest of a patient ; a release sensor providing information as to whether the rescuer &# 39 ; s hands are in contact with the release sensor during manual chest compressions or not in contact with the release sensor between manual chest compressions ; a computing unit ; and an audio and / or visual display providing feedback received from the computing unit to the rescuer regarding chest compression rate , chest compression depth and whether the rescuer &# 39 ; s hands are not in contact with the release sensor between manual chest compressions .