attributable to the presence of the first 3 links were 4.4, 3.7, and 3.4, respectively.64 Data supporting the fourth link, early ACLS, has been less definitive. Although a meta-analysis suggested that the odds ratio of survival from outpatient arrest by resuscitation with ACLS versus without ACLS was 2.3,65 the OPALS study found no improvement in outpatient survival with the addition of ACLS