Association of Serum Magnesium Level at Emergency Department Arrival and Favorable Neurologic Outcome for Out-of-Hospital Cardiac Arrest

Abstract

Introduction Electrolyte disturbances are associated with sudden cardiac arrest based on several cohort studies. However, little is known about the association between serum magnesium (S-Mg) level at ED arrival and survival of out-of-hospital cardiac arrest (OHCA) patients.

Hypothesis We hypothesized S-Mg level at ED arrival is associated with favorable neurologic outcome of OHCA patients.

Methods This is an observational study using Korean Cardiac Arrest Research Consortium (KoCARC) data from October 2015 to June 2020. EMS treated OHCA patients over 18 years old who survived to ICU admission were included. Those without S-Mg level were excluded. Exposure is S-Mg level at emergency department (ED) arrival and outcome was favorable neurologic outcome (cerebral performance category 1 or 2) at hospital discharge. S-Mg was categorized into three groups; Low group; 0-1.7mg/dl, Normal group;1.7- 2.3mg/dl, High group; over 2.3mg/dl). Multivariable logistic regression was performed to calculate adjusted odds ratios (AORs) with 95% confidence intervals (95% CIs) for outcome.

Results From total 10,897 OHCA patients, 2,789 patients survived to ICU admission and 1,370 patients had initial S- Mg result. Neurologically favorable survival rate was 55.6% in normomagnesemia group, 27.0% in hypomagnesemia group and 22.9% in hypermagnesemia group. After adjusting out-of-hospital, hospital resuscitation and laboratory covariates, compared to normomagnesemia group, hypomagnesemia group (AOR 0.21 (95% CI 0.07-0.68)) and hypermagnesemia group (AOR 0.41 (95% CI 0.19-0.87)) showed worse outcome.

Conclusion Low (S-Mg less than 1.7 mg/dl) or high (S-Mg over 2.3mg/dl) S-Mg level measured initially at ED arrival for OHCA patients was associated with worse neurologic outcome compared to normal S-Mg level (S-Mg 1.7- 2.3mg/dl). Based on this study, further study is needed to investigate the optimized S-Mg level for OHCA patient under resuscitation.