Abstract: The invention relates to a device for assisting a first aider with a cardiopulmonary resuscitation of a person suffering cardiac arrest, comprising a transport housing (1), in which a sensor apparatus (4) and two adhesive electrodes (2), which are or can be connected to the sensor apparatus (4), can be stowed. The sensor apparatus (4) allows data to be acquired while the first-aid measures for resuscitation are performed. The sensor apparatus (4) comprises an adhesive (5) for attachment to the chest of the patient (3). The chest compressions, i.e. depth of compression and compression frequency, can be detected by means of a motion sensor. An interface for data transfer allows wireless communication with a mobile terminal (6). Furthermore, the sensor apparatus (4) contains a high-voltage store so that, after connection to the adhesive electrodes (2), a single defibrillation shock can be delivered.