Quality of out-of-hospital cardiopulmonary resuscitation with real time automated feedback: A prospective interventional study

Aims: To compare quality of CPR during out-of-hospital cardiac arrest with and without automated feedback. Materials and methods: Consecutive adult, out-of-hospital cardiac arrests of all causes were studied. One hundred and seventy-six episodes (March 2002-October 2003) without feedback were compared to 108 episodes (October 2003-September 2004) where automatic feedback on CPR was given. Automated verbal and visual feedback was based on measured quality with a prototype defibrillator. Quality of CPR was the main outcome measure and survival was reported as specified in the protocol. Results: Average compression depth increased from (mean S.D.) 34 9 to 38 +/- 6mm (mean difference (95% Cl) 4 (2, 6), P < 0.001), and median percentage of compressions with adequate depth (38-51 mm) increased from 24% to 53% (P < 0.001, Mann-Whitney U-test) with feedback. Mean compression rate decreased from 121 +/- 18 to 109 +/- 12 min(-1) (difference -12 (-16, -9), P=0.001). There were no changes in the mean number of ventilations per minute; 11 +/- 5 min(-1) versus 11 +/- 4 min(-1) (difference 0 (-1,1), P=0.8) or the fraction of time without chest compressions; 0.48 +/- 0.18 versus 0.45 +/- 0.17 (difference -0.03 (-0.08, 0.01), P=0.08). With intention to treat analysis 7/241 control patients were discharged alive (2.9%) versus 5/117 with feedback (4.3%) (OR 1.5 (95% Cl; 0.8, 3), P=0.2). In a logistic regression analysis of all cases, witnessed arrest (OR 4.2 (95% Q 1.6, 11), P=0.004) and average compression depth (per mm increase) (OR 1.05 (95% Cl; 1.01, 1.09), P=0.02) were associated with rate of hospital admission. Conclusions: Automatic feedback improved CPR quality in this prospective non-randomised study of out-of-hospitat cardiac arrest. Increased compression depth was associated with increased short-term survival.