Two studies published July 29 by the New England Journal of Medicine support compression only CPR for bystanders. Both found no difference in patient survival when bystanders received dispatch instructions for compression only compared to compression plus rescue breathing. One study used hospital discharge as the endpoint: http://www.nejm.org/doi/full/10.1056/NEJMoa0908993. The other study used survival at 30 days: http://www.nejm.org/doi/full/10.1056/NEJMoa0908991.