Abstract: In embodiments, a CPR chest compression system includes a retention structure that can retain the patient's body, and a compression mechanism that can perform automatically CPR compressions and releases to the patient's chest. The compression mechanism can pause the performing of the CPR compressions for a short time, so that an attendant can check the patient. The CPR system can include a user interface that can output a human-perceptible check patient prompt, to alert an attendant to check the patient during the pause. The compression mechanism can during a CPR session retreat a distance away from the patient's chest whereby the patient's chest can expand without active decompression of the patient's chest beyond the chest's natural resting position.

Abstract: The present invention relates to a drive mechanism for a spring assisted injection device configured for setting and expelling set doses of a drug. The drive mechanism comprises an assembly provided by a rotatable piston driver (6), a rotatable counter-element (15) and a spring device (19) tensioned between the piston driver (6) and the counter-element (15). During dose setting and during dose expelling the piston driver (6) and the counter-element (15) move relatively along an axis. A releasable interlock (6c, 15d) is provided for maintaining the piston driver (6) and the counter-element (15) in a fixed relative axial condition wherein the spring device (19) is in a tensioned state. The interlock provides for a simplified manufacturing process. The invention also relates to a method of assembling an injection device.