Increased chest compression to ventilation ratio improves delivery of CPR

Chest compressions are interrupted during cardiopulmonary resuscitation (CPR) due to human error, for ventilation, for rhythm analysis and for rescue shocks. Earlier data suggest that the recommended 15:2 compression to ventilation (C:V) ratio results in frequent interruptions of compressions during CPR. We evaluated a protocol change from the recommended C:V ratio of 15:2-30:2 during CPR in our municipal emergency medical system.

Municipal firefighters (N=875) from a single city received didactic and practical training emphasizing the importance of continuous chest compressions and recommending a 30:2 C:V ratio. Both before and after the training, digital ECG and voice records from all first-responder cases of out-of-hospital cardiac arrest were examined off-line to quantify chest compressions. The number of chest compressions delivered and the number and duration of pauses in chest compressions were compared by t-test for the first three 1min intervals when CPR was recommended.

More compressions were delivered during minutes 1, 2, and 3 during CPR with the 30:2 C:V ratio (78+/-29, 80+/-30, 74+/-26) than with the 15:2C:V ratio (53+/-24, 57+/-24, 51+/-26) (p<0.001). Fewer pauses for ventilation occurred during each minute with the 30:2 C:V ratio (1.7+/-1.2, 2.2+/-1.2, 1.8+/-1.0) than with the 15:2C:V ratio (3.4+/-2.6, 4.7+/-7.2, 4.0+/-2.9) (p< or =0.01). Degradation of the final ECG to asystole occurred less frequently after the protocol change (asystole pre 67.1%, post 56.8%, p<0.05). The incidence of return of spontaneous circulation was not altered following the protocol change.

Retraining first responders to use a C:V ratio of 30:2 instead of the traditional 15:2 during out-of-hospital cardiac arrest increased the number of compressions delivered per minute and decreased the number of pauses for ventilation. These data are new as they produced persistent and quantifiable changes in practitioner behavior during actual resuscitations.