Quality of bystander cardiopulmonary resuscitation (CPR) affect patient survival. Quality of professional CPR on patients has not been studied in detail, but it is regularly reported that the quality when tested on manikins deteriorates dramatically within months after training. Automated direct feedback on CPR quality from manikins brings quality back within a couple of minutes. Similar feedback has been incorporated into a defibrillator which also monitors quality of CPR. We hypothesise that quality of professional clinical CPR improves with such feedback