Fifty-four studies were included in the review (23,752 patients, range seven to 2,984). Thirty-one studies were good quality, 11 studies were fair and 12 studies were poor.
Vasopressors compared to placebo: Three randomised trials, one retrospective study, one prospective observational study (4,078 patients) rated as good, fair and poor quality.
Improvements in return of spontaneous circulation and hospital admission were observed in two trials but no significant differences were observed in survival to hospital discharge.
Vasopressin compared to epinephrine: One meta-analysis, eight RCTs, four level three studies and one study each at non-randomised trials and one single-group study (6,440 patients).
A meta-analysis of three trials that compared vasopressin and epinephrine found no differences in failure of return of spontaneous circulation, death before hospital admission death within 24 hours and death prior to hospital discharge. All RCTs found neutral results of comparisons between vasopressins and vasopressins used with epinephrine compared to epinephrine alone.
High-dose epinephrine compared to low-dose epinephrine: One meta-analysis, eight RCTs, two non-randomised trials, three retrospective studies and three single group studies (8,443 patients).
Three randomised trials showed significantly improved rates of return of spontaneous circulation and two showed improved rates of hospital admission with high-dose epinephrine (dose not defined) compared to standard dose epinephrine (1mg). The other five clinical trials showed no differences between epinephrine doses in return to spontaneous circulation, survival to hospital admission and discharge and neurological outcomes.
Alternate vasopressors compared to epinephrine: Six RCTs and one single group study (3,067 patients).
Three randomised trials found no differences in outcomes with epinephrine compared to methoxamine in return of spontaneous circulation or survival to hospital discharge. Norepinephrine was associated with higher rates of initial return of spontaneous circulation compared to standard dose epinephrine but there were no differences in long-term survival or neurological outcomes (although there were trends observed towards worse cerebral performance with norepinephrine). Similar rates of return of spontaneous circulation were observed in one trial of phenylephrine and epinephrine.
Vasopressors in paediatric populations: Two RCTs, four retrospective studies and four single group studies (1,724 patients).
Five studies found no differences between high dose epinephrine and low dose epinephrine in return of spontaneous circulation, survival data and neurological outcomes.