Furthermore, “There are no alternative vasopressors that provide a long-term survival benefit when compared to epinephrine,” the authors report.
Dr. Todd M. Larabee, at the University of Colorado Denver School of Medicine, and colleagues note that the effectiveness of vasopressors in cardiac arrest is controversial. However, because they are used routinely in this setting, placebo-controlled trials are scarce.
They reviewed the literature and identified 53 articles that addressed five areas: outcomes comparing any vasopressor to placebo; outcomes comparing vasopressin to epinephrine; outcomes comparing high dose epinephrine to standard dose epinephrine; outcomes comparing any alternative vasopressor (other than vasopressin) to epinephrine; and outcomes in pediatric cardiac arrest.
Five trials compared any vasopressor to placebo, and the authors conclude that epinephrine improves short-term survival but not survival to hospital discharge.
Overall, they found, vasopressin is comparable to epinephrine, based on the outcomes of 15 trials. For example, a meta-analysis of data from 1519 patients in three RCTs revealed no difference between vasopressin and epinephrine groups regarding the failure of return of spontaneous circulation (ROSC) (risk ratio 0.81), death before hospital admission (RR 0.72), death within 24 hours (RR 0.74) and death before hospital discharge (RR 0.96).
Seventeen studies looked at high-dose vs low-dose epinephrine; outcomes in three trials favored the high-dose strategy, three opposed it, and results in the others were neutral. The researchers note that high-dose epinephrine does appear to improve ROSC, but is not as effective as standard dosing in terms of long-term outcomes.
A total of six studies looked at alternative vasopressors to epinephrine – that is, methoxamine, norepinephrine, dopamine or phenylephrine. As mentioned, none proved better than epinephrine for long-term survival or neurologic outcome, although initial ROSC were higher with norepinephrine.
As for use vasopressors in pediatric cardiac arrest, Dr. Larabee and colleagues found limited data and say further studies are needed in this population.
In discussing their findings, they comment: “When considering the long-term outcomes, it is now clear that there are many other factors and interventions which play a role in survival to hospital discharge with good neurologic outcome, some of which are influenced by the components of post-resuscitative care and innovations in cerebral protection such as therapeutic hypothermia. It is not likely the case that the vasopressor therapy is the sole responsible agent effecting long-term outcomes, although we cannot say that vasopressor use does not play some role.”