The present invention relates generally to a support structure for fixating a patient to a treatment unit, and especially to a support structure for fixating the patient to a cardiopulmonary resuscitation unit. An embodiment of the support structure includes a back plate for positioning behind said patient's back posterior to said patient's heart and a front part for positioning around said patient's chest anterior to said patient's heart. Further, the front part can include two legs, each leg having a first end pivotably connected to at least one hinge and a second end removably attachable to said back plate. Said front part can further be devised for including a compression/decompression unit arranged to automatically compress or decompress said patient's chest when said front part is attached to said back plate.