This is an investigator-initiated, multicenter, randomized, placebo-controlled, parallel
group, double-blind, superiority trial of calcium during adult out-of-hospital cardiac
arrest. 430 adult patients with out-of-hospital cardiac arrest receiving at least one dose of
adrenaline will be enrolled. The primary outcome is sustained return of spontaneous
circulation and key secondary outcomes include survival at 30 days and survival at 30 days
with a favorable neurological outcome.