Restarting the heart: Calcium for cardiac arrest


Calcium for Out-of-Hospital Cardiac Arrest – A Randomized, Double-Blind, Placebo-Controlled Trial


To test whether calcium chloride (CaCl) – in addition to standard treatment – can improve the proportion of patients regaining spontaneous circulation at hospital arrival.


A randomized, double-blind, placebo-controlled trial of calcium administration during adult out-of-hospital cardiac arrest in 430 patients in the Central Denmark Region. The trial will be double-blind; patients, investigators, and the clinical team will be blinded to the allocation.


The trial will be conducted in the Central Denmark Region’s prehospital setting, where three distinct units can give adrenaline to a patient with out-of-hospital cardiac arrest: physician-manned ambulances, paramedic-manned ambulances, and hospital emergency medicals services (HEMS). Participating stations will be any regional ambulance station which holds one or more physician- and/or paramedic-manned ambulances.


The trial will be conducted in the Central Denmark Region and 430 patients will be included. Inclusion criteria are: 1) out-of-hospital cardiac arrest; 2) Age ≥18 years; 3) Received at least one dose of adrenaline during CPR. Exclusion criteria: 1) Traumatic cardiac arrest; 2) Known or strongly suspected pregnancy; 3) Prior enrollment in the trial; 4) Already received one dose of adrenaline by a non-participating unit; 5) Clinical indication for calcium administration during the cardiac arrest.


The intervention will consist of 5 mmol (10 mL ampoule) of CaCl administered immediately after the first dose of adrenaline and again after the second dose of adrenaline. No further doses will be administered, and the study has no other interventions. The placebo will consist of 10 mL of 9 mg/mL sodium chloride (NaCl, “normal saline”) from a 10 mL ampoule identical to the CaCl ampoules.


The primary outcome will be return of spontaneous circulation. Return of spontaneous circulation will be defined as palpable pulses at time of hospital arrival consistent with the Danish Cardiac Arrest Registry and other large trials. Key secondary outcomes will include survival as well as neurological outcome at 30 days. Neurological outcome will be assessed with the modified-Rankin Scale. We will include 90-day survival as a measure of long-term survival.


Since patients present to the ED with symptoms, that we broadly categories into chief complaints, and not with diagnoses, we believe this investigation of characteristics and causal associations for the chief complaint, dyspnoea, can add new, very clinical useful information. Dyspnea is one of the most frequent chieft complaints in the ED and we hypothesize that the mortality and readmission rates are higher among this patient group compared to other chief complaints (cardiac arrest, alterated level of conscience). We plan to publish two or more articles on this subject.

Conflicts of interest

None. The project is funded by the Novo Nordic Foundation, Aarhus University, and the Health Research Foundation of Central Denmark Region (see our website for details). The funding agencies have no role in the design and conduct of the study; collection, management, analysis, and interpretation of the data; preparation, review, or approval of any manuscripts; or the decision to submit any manuscripts for publication.


Prehospital Emergency Medicals Services, Central Denmark Region (Aarhus, Denmark)