Effects of Intrathecal Magnesium Administration on Neurologic Outcomes in a Porcine Model of Asphyxial Cardiac Arrest.

Abstract

BACKGROUND: Magnesium mitigates several mechanisms involved in secondary brain injury after cardiac arrest. Because systemically administered magnesium crosses the blood-brain barrier poorly, it may be unsuitable for early post-cardiac arrest neuroprotection. We tested whether intrathecal magnesium (IT-Mg), which bypasses the blood-brain barrier, improves neurologic outcomes in a porcine model of asphyxial cardiac arrest. METHODS: Twenty-four pigs underwent asphyxial cardiac arrest and cardiopulmonary resuscitation. Thirty minutes after return of spontaneous circulation, the IT-Mg group received 75&#x2009;mg of magnesium via cranial intrathecal catheters; the control group received no IT-Mg treatment. Animals were observed for up to 72&#x2009;hours post return of spontaneous circulation. RESULTS: Survival duration and cumulative survival did not differ significantly between groups. In controls, the mean amplitude-integrated electroencephalography amplitude remained depressed for 24&#x2009;hours, whereas it increased in the IT-Mg group (group&#xd7;time interaction<0.001). Compared with controls, the IT-Mg group demonstrated superior neurologic function (lower overall performance category, group effect=0.039; lower neurologic deficit score, group effect=0.013) and reduced histologic injury (lower temporal cortical [=0.038] and total [=0.041] histologic damage scores). CONCLUSIONS: Intrathecal administration of magnesium after return of spontaneous circulation mitigated histologic injury and improved neurologic function in a porcine model of asphyxial cardiac arrest.