A positioning device for use in apparatus for treating sudden cardiac arrest in a patient in supine position by providing chest compression at the lower end of the sternum prevents the apparatus from moving in a caudal direction. The apparatus comprises a frame enclosing the patient at a sternal transversal plane and a pneumatic compression/decompression means mounted on the frame. The device comprises a flexible strap having a first end, a second end and a tensioning means disposed between the first and second ends. First and second end portions of the strap comprise means for attachment of the apparatus. The flexible strap has amounted tensioned length sufficient to extend around the patients neck. At least one of the end portions is releasably attached.
