The effectiveness of magnesium for neuroprotection during global cerebral ischemia associated with cardiac arrest or cardiac surgery

Abstract

The objective of this systematic review derived thesis is to present the best available evidence on the use of magnesium for neuroprotection during global cerebral ischemia associated with cardiac surgery and cardiac arrest in adults. This systematic review utilizes the JBI methodology for quantitative reviews presenting JBI level of evidence 1.a (a systematic review of randomised controlled trials). The presupposition of this thesis is that for patients who survive global ischemia, improved neurological outcome can improve quality of life. This review considered adults above 18 years of age without pre-existing neurological deficits. The intervention of interest was magnesium administered in doses of at least of two grams compared to placebo to adult patients within 24 hours of cardiac arrest or cardiac surgery. Seven trials were included in this review with 988 participants meeting the inclusion criteria. To enable assessment of the available datum, neuroprotection was examined by breaking down neurological outcomes into three domains; functional neurological outcomes, neurophysiological outcomes and cognitive function. The evidence presented in this review highlights the fact that magnesium may provide improved functional neurological outcome for patients with global cerebral ischemia. However, current evidence does not support the view that magnesium improves long-term cognitive function. The individual studies investigating the neuroprotective effects of magnesium during cardiac arrest did not show statistical improvement on neurological outcome. Pooled datum using meta-analysis from the three trials favored magnesium to improve neurological outcome post cardiac arrest. There was no data available for neurophysiological and cognitive function post cardiac arrest. For patients post cardiac surgery, there is limited evidence to suggest that magnesium administration may improve functional neurological and neurophysiological outcomes. There was no improvement noted in cognitive function, where cognitive decline is noted in both placebo and magnesium populations. This review concludes that research into the neuroprotective properties of magnesium is somewhat fragmented, with no standard criteria to assess all of the neurological outcome domains. Future research on neuroprotection should involve outcomes from each of the neurological domains, at multiple time points in combination with imaging modalities.