Table 1.

Characteristics of randomised trials for adult out-of-hospital cardiac arrest.

Study	Country	Year of inclusion	Main inclusion criteria	Patients	Location of cardiac arrest	Age group	Time of exposure	Intervention	Control	Risk of bias
Stueven, 1985 (EMD)1	USA	1982–1983	OHCA patient in refractory EMD at time of randomisation (had adrenaline and bicarbonate).	90	OHCA	Adult	Unclear	IV calcium chloride	Saline	High
Stueven, 1985 (Asystole)2	USA	1982–1983	OHCA patient in asystole at time of randomisation; refractory asystole (had adrenaline, atropine and bicarbonate)	73	OHCA	Adult	Unclear	IV calcium chloride	Saline	High
Vallentin, 20219	Denmark	2020–2021	≥18 years OHCA adults who received at least 1 dose of epinephrine during cardiac arrest	391	OHCA	Adult	During CPR, after first dose of epinephrine	IV or IO calcium chloride	Saline	Low
Vallentin, 202210

EMD: Electromechanical dissociation; OHCA: Out-of-hospital cardiac arrest; VF: Ventricular fibrillation; VT: Ventricular tachycardia.