Magnesium sulfate increases the rate of hypothermia via surface cooling and improves comfort.
OBJECTIVE
Therapeutic hypothermia shows promise as a treatment for acute stroke. Surface cooling techniques are being developed but, although noninvasive, they typically achieve slower cooling rates than endovascular methods. We assessed the hypothesis that the addition of intravenous MgSO4 to an antishivering pharmacological regimen increases the cooling rate when using a surface cooling technique.


METHODS
Twenty-two healthy volunteers were studied. Hypothermia was induced using a surface technique with a target tympanic temperature (Ttym) of 34.5 degrees C (target range 34 to 35 degrees C). Subjects received 1 of the following pharmacological regimens: (1) meperidine monotherapy (n=5); (2) meperidine plus buspirone, 30 to 60 mg PO administered at the time of initiation of cooling (n=4); (3) meperidine and ondansetron, 8 to 16 mg IV administered as an 8 mg bolus at the time of initiation of cooling with an optional second dose after 4 hours as needed for nausea (n=5); or (4) meperidine, ondansetron, and MgSO4, 4 to 6 g IV bolus followed by 1 to 3 g per hour infusion (n=8). Thermal comfort was evaluated with a 100-mm-long visual analog scale.


RESULTS
More subjects who received MgSO4 were vasodilated during hypothermia induction (7 of 8 [88%] versus 4 of 14 [29%]; P=0.024). MgSO4 (coefficient -17.265; P=0.039), weight (1.838, 0.001), and the initial 2-hour meperidine dose (0.726, 0.003) were found to significantly impact the time to achieve Ttym of 35 degrees C. Subjects who received MgSO(4) had significantly higher mean comfort scores than those who did not (48+/-15 versus 38+/-12; P<0.001).


CONCLUSIONS
Administration of intravenous MgSO(4) increases the cooling rate and comfort when using a surface cooling technique.
Zweifler
Richard M
RM
University of South Alabama Stroke Center, Mobile, Ala 36617, USA. rzweifle@usouthal.edu
Voorhees
Marc E
ME
Mahmood
M Asim
MA
Parnell
Mel
M
D000328:Adult; D000700:Analgesics / Q000627:therapeutic use*; D001831:Body Temperature / Q000187:drug effects; D002065:Buspirone / Q000627:therapeutic use; D005260:Female; D006801:Humans; D007036:Hypothermia, Induced / Q000379:methods; D007262:Infusions, Intravenous; D008278:Magnesium Sulfate / Q000627:therapeutic use*; D008297:Male; D008614:Meperidine / Q000627:therapeutic use; D008875:Middle Aged; D017294:Ondansetron / Q000627:therapeutic use; D018490:Serotonin Agents / Q000627:therapeutic use
D000700:Analgesics; D018490:Serotonin Agents; D017294:Ondansetron; D008278:Magnesium Sulfate; D008614:Meperidine; D002065:Buspirone