Cerebral blood flow is thought to increase at high altitude and in subjects suffering from acute mountain sickness (AMS); however, data from the literature are contentious. Blood flow velocity in the middle cerebral artery (MCAv) may be used as a proxy measure of cerebral blood flow. Using transcranial Doppler sonography, MCAv was measured during normo- and hyper-ventilation in subjects who participated in a trial that tested the effect of magnesium supplementation on the prevention of AMS. First, MCAv was recorded at 353 m (baseline). Subjects were then randomized to receive oral magnesium citrate and matching placebo. A second measurement was taken after a 24±2 h ascent from 1130 m to 4559 m (altitude I), and a third after a 20–24 h stay at 4559 m (altitude II). Using multivariate linear regression, an association was sought between MCAv and magnesium supplementation, subjects′ age and gender, altitude itself, a temporary stay at altitude, and the presence of AMS (Lake Louise Score >6 with ataxia, nausea and/or headache). Subjects with AMS had additional Doppler recordings immediately before and after rescue medication (oxygen, dexamethasone and acetazolamide). Forty-seven subjects had measurements at baseline, 39 (21 receiving magnesium and 18 placebo) at altitude I and 26 (13 receiving magnesium and 13 placebo) at altitude II. During hyperventilation, MCAv decreased consistently (for each measurement, P<0.001). Magnesium significantly increased MCAv by 8.4 cm·s-1 (95% confidence interval, 1.8–15), but did not prevent AMS. No other factors were associated with MCAv. Eleven subjects had severe AMS [median score (range), 11 (8–16)] and, after rescue medication, the median score decreased to 3 (range, 0–5; P=0.001), but MCAv remained unchanged (65±18 cm·s-1 before compared with 67±16 cm·s-1 after rescue medication; P=0.79). MCAv was increased in subjects who received magnesium, but was not affected by exposure to high altitude or by severe AMS.
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Research Article|
March 01 2004
Effect of magnesium, high altitude and acute mountain sickness on blood flow velocity in the middle cerebral artery
Christopher LYSAKOWSKI;
*Neuroanaesthesia Unit, Division of Anaesthesiology, Department of Anaesthesiology, Pharmacology and Surgical Intensive Care, Geneva University Hospitals, Geneva, Switzerland
Correspondence: Dr Christopher Lysakowski (e-mail [email protected]).
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Erik VON ELM;
Erik VON ELM
†Perioperative Evidence-Based Medicine Program, Division of Anaesthesiology, Department of Anaesthesiology, Pharmacology and Surgical Intensive Care, Geneva University Hospitals, Geneva, Switzerland
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Lionel DUMONT;
Lionel DUMONT
*Neuroanaesthesia Unit, Division of Anaesthesiology, Department of Anaesthesiology, Pharmacology and Surgical Intensive Care, Geneva University Hospitals, Geneva, Switzerland
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Jean-Daniel JUNOD;
Jean-Daniel JUNOD
*Neuroanaesthesia Unit, Division of Anaesthesiology, Department of Anaesthesiology, Pharmacology and Surgical Intensive Care, Geneva University Hospitals, Geneva, Switzerland
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Edömer TASSONYI;
Edömer TASSONYI
*Neuroanaesthesia Unit, Division of Anaesthesiology, Department of Anaesthesiology, Pharmacology and Surgical Intensive Care, Geneva University Hospitals, Geneva, Switzerland
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Bengt KAYSER;
Bengt KAYSER
‡Faculty of Medicine, University of Geneva, Geneva, Switzerland
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Martin R. TRAMÈR
Martin R. TRAMÈR
*Neuroanaesthesia Unit, Division of Anaesthesiology, Department of Anaesthesiology, Pharmacology and Surgical Intensive Care, Geneva University Hospitals, Geneva, Switzerland
†Perioperative Evidence-Based Medicine Program, Division of Anaesthesiology, Department of Anaesthesiology, Pharmacology and Surgical Intensive Care, Geneva University Hospitals, Geneva, Switzerland
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Publisher: Portland Press Ltd
Received:
May 27 2003
Revision Received:
September 24 2003
Accepted:
October 22 2003
Accepted Manuscript online:
October 22 2003
Online ISSN: 1470-8736
Print ISSN: 0143-5221
© 2004 The Biochemical Society
2004
Clin Sci (Lond) (2004) 106 (3): 279–285.
Article history
Received:
May 27 2003
Revision Received:
September 24 2003
Accepted:
October 22 2003
Accepted Manuscript online:
October 22 2003
Citation
Christopher LYSAKOWSKI, Erik VON ELM, Lionel DUMONT, Jean-Daniel JUNOD, Edömer TASSONYI, Bengt KAYSER, Martin R. TRAMÈR; Effect of magnesium, high altitude and acute mountain sickness on blood flow velocity in the middle cerebral artery. Clin Sci (Lond) 1 March 2004; 106 (3): 279–285. doi: https://doi.org/10.1042/CS20030188
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