X-Message-Number: 30108
Date: Thu, 6 Dec 2007 10:00:26 -0800 (PST)
Subject: Magnesium sulfate increases the rate of hypothermia

Stroke. 2004 Oct;35(10):2331-4. Epub 2004 Aug 19.
Magnesium sulfate increases the rate of hypothermia via surface cooling and
improves comfort.
  Zweifler RM, Voorhees ME, Mahmood MA, Parnell M. University of South
Alabama Stroke Center, Mobile, Ala 36617, USA.
BACKGROUND AND PURPOSE: 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
PMID: 15322301

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