Abstract 109: Effect of the Metronome-Guidance on the Quality of Closed Chest Compression During One Person Cardiopulmonary Resuscitation
Background: The metronome-guidance had been thought as a useful method to enhance the quality of cardiopulmonary resuscitation (CPR) by keeping the pace of chest compression (CC). Recent studies showed that the metronome-guidance (MG) significantly lower the average depth of chest compression during CPR. However, the specific mechanism of this deterioration was not known, and only the rescuer fatigue (RF) caused by the emotional stress to keep the pace of MG was suggested as a possible cause. Moreover, there was the evidence which showed the positive effect of the MG to the compression-ventilation rate of CPR. We aimed to assess the effect of the MG on the RF and to find the way to improve the quality of CPR under the MG.
Methods: This is a randomized controlled trial of 32 senior medical students performing one person CPR according to 2005 AHA CPR guidelines for adults on a ResusciAnne simulator. The subjects were assigned to the group with the MG or without, and directed to perform CPR as long as they could. Average depth of CC, total CPR time, work-load (total compression count X average depth), and the depth of first 5 cycles were measured and compared. 10 of the subjects were also enrolled to the crossover trial performing one-minute CC only CPR under 4 different rates (80, 100, 120, 140/minute) of the MG and without a metronome.
Results: Average depths, work-load, and the estimated median CPR time from the Kaplan-Meier analysis did not show significant differences between the groups with the MG and without (p=0.233, 0.463, and 0.662, respectively). Average depth of first 5 cycles of CPR showed a significant difference (52.5 vs. 47.2 mm, p=0.021). Repeated measure ANOVA showed a significant linear increase of average depth as the rate of metronome increased (p=0.003). Average depth of CC without MG showed significant differences with 80 and 100 per minute (p=0.005, 0.014), but did not show a difference with 120, 140 per minute.
Conclusions: The deterioration in the quality of CPR with metronome-guidance may be caused by the relatively slow rate of metronome, rather than the rescuer-fatigue primarily caused by the metronome itself. To improve this, the rate of metronome should be set faster than 100 per minute.
- © 2010 by American Heart Association, Inc.