Now there is a disturbing report of a possible downside to the guideline changes: resumption of compressions may shorten the time to recurrent VF:
Of 361 patients, 136 met the inclusion criteria: 68 were randomly assigned to GL2000 and 68 to GL2005. Rescuers resumed CPR 30 (21-to-39) and 8 (7-to-9) seconds, respectively, after the first shock that successfully terminated VF (P less than 0.001); VF recurred after 40 (21-to-76) and 21 (10-to-80) seconds, respectively (P=0.001). The time interval between start of CPR and VF recurrence was 6 (0-to-67) and 8 (3-to-61) seconds, respectively (P=0.88). The hazard ratio for VF recurrence in the first 2 seconds of CPR was 15.5 (95% confidence interval, 5.63 to 57.7) compared with before CPR resumption. After more than 8 seconds of CPR, the hazard of VF recurrence was similar to before CPR resumption.
Conclusions— Early CPR resumption after defibrillation causes early VF recurrence.
We don't know what this ultimately means in terms of outcomes. The advantages of the more aggressive CPR strategy in GL2005 may outweigh an increased risk of earlier recurrent VF.