Effects of magnesium sulphate on cerebral haemodynamics in healthy volunteers: a transcranial Doppler study.
BACKGROUND
Magnesium is increasingly being considered as a neuroprotective agent. We aimed to study its effects on middle cerebral artery blood flow velocity (V(mca)), cerebral autoregulation and cerebral vascular reactivity to carbon dioxide (CRCO(2)) in healthy volunteers.


METHODS
Fifteen healthy volunteers were recruited. Using transcranial Doppler ultrasonography, V(mca) was recorded continuously. The strength of autoregulation was assessed by the transient hyperaemic response test, and the CRCO(2) was measured by assessing changes in V(mca) to the induced changes in end-tidal carbon dioxide. I.V. infusion of magnesium sulphate was then started (loading dose of 16 mmol followed by an infusion at the rate of 2.7 mmol h(-1)) for 45 min. The cerebral haemodynamic variables were measured again near the end of the infusion of magnesium sulphate.


RESULTS
Total serum magnesium levels were doubled by the infusion regimen. However, there were no significant changes in V(mca), strength of autoregulation, or CRCO(2). Five of the volunteers reported marked nausea and two developed significant hypotension during the loading dose.


CONCLUSIONS
Infusion of magnesium sulphate, in a dose that doubles its concentration in plasma, does not affect V(mca), strength of autoregulation or CRCO(2) in healthy volunteers. However, it can be associated with nausea and hypotension.
Sherman
R
R
University Department of Anaesthesia and Intensive Care and Department of Neurosurgery, University Hospital and City Hospital, Nottingham, UK.
Armory
P
P
Moody
P
P
Hope
T
T
Mahajan
R P
RP
D000293:Adolescent; D000328:Adult; D002560:Cerebrovascular Circulation / Q000187:drug effects* / Q000502:physiology; D005260:Female; D006439:Hemodynamics / Q000187:drug effects; D006706:Homeostasis / Q000187:drug effects; D006801:Humans; D007022:Hypotension / Q000139:chemically induced; D008274:Magnesium / Q000097:blood; D008278:Magnesium Sulfate / Q000009:adverse effects / Q000494:pharmacology*; D020768:Middle Cerebral Artery / Q000000981:diagnostic imaging / Q000187:drug effects / Q000502:physiology; D009325:Nausea / Q000139:chemically induced; D018696:Neuroprotective Agents / Q000009:adverse effects / Q000494:pharmacology*; D017585:Ultrasonography, Doppler, Transcranial
D018696:Neuroprotective Agents; D008278:Magnesium Sulfate; D008274:Magnesium