Journal of
Cardiothoracicand Vascular Anesthesia JUNE 1991
VOL 5, NO 3
EDITORIAL Magnesium:
Its Time Has Come
HYSIOLOGISTS HAVE known of the importance of magnesium to the body for many years. Clinicians ignored them. Zwillinger reported the use of magnesium salts for the treatment of dysrhythmias in 1935.’ Clinicians ignored this as well. Magnesium remained a drug almost exclusively the property of obstetricians2.3 and nutritionists.4 Over the past decade there has been a reawakening of interest and many studies have been carried out to elucidate its role in a variety of disease states. These have ranged from osteoporosis in the postmenopausal woman,’ to asthma,” tetanus,’ central nervous system injury,8 intubation9 hypertension with pheochromocytoma,“’ insulin resistance,” and dysrhythmias in the patient with cardiac disease,‘* including those after myocardial infarction” and cardiac surgery.14 Review articles are beginning to appear in the anesthesia literature,” demonstrating that some knowledge of the activities of this divalent cation might be useful to the practicing clinician, and that more frequent measurement and use of magnesium therapeutically might be helpful to our patients-even those outside the obstetrical units. The increased level of interest might even heighten the efforts to produce a clinically useable ion-selective electrode for use in a stat laboratory.‘6 The study by Aglio et al” in this issue of the JOURNAL speaks to the changes in serum magnesium levels after cardiac surgery and represents another of the Chernow group’s investigations of the significance of changes in magnesium in various surgical settings. They demonstrated that low magnesium levels were common preoperatively. In my experience this is a finding often associated with diabetes, and diuretic or alcohol use, conditions common in this population. Hypomagnesemia also occurred in the majority of patients postoperatively. Other groups have made similar observations. Their study has broadened our understanding of magne-
P
sium homeostasis by including determination of ultrafilterable magnesium, parathyroid hormone, and fatty acids, but might have benetitted from observations carried further into the postoperative period to better delineate the time frame of presumed risk. Serum values for total magnesium have returned to normal between the second and third postoperative days in our experience. Despite the lack of a prolonged study, their information is useful in assessing the significance and limitations of the total magnesium concentration. They point out, correctly, that the ultrafilterable fractions may be a more useful way to assess magnesium status, because ionized levels are impossible to determine, and, as is the case with calcium, are probably impossible to assess indirectly from pH and protein concentrations. The implications for therapy are obvious. Hypomagnesemia is common after coronary artery bypass and other types of cardiac surgery. As has been the case with potassium for many years, regular determination of magnesium blood levels and its administration prophylactically in the perioperative period appear to be beneficial in the control of ectopy_‘8 Further, it may be useful in the elimination of perioperative coronary artery spasm.” It is a measurement and a therapy whose time has come, and with more studies like this, appears well on the way to becoming a standard of care in patients with cardiac disease in the surgical setting. Donald C. Finlayson, MD, FRCP(C)
Clinical Professor of Anesthesiology Medical College of Georgia Augusta, GA Director, Divisions of Cardiothoracic Anesthesia and Critical Care Medicine Georgia Baptist Medical Center Atlanta, GA
REFERENCES 1.
Zwillinger L: Uber die magnesiumwirkung auf das herz. Klin
Wehnscher 14:1429-1433,1935 2. Lee ML, Todd HM, Bowe A: The effects of magnesium sulphate infusions on blood pressure and vascular responsiveness during pregnancy. Am J Obstet Gynecol149:705-708,1984 3. Kisters K, Niedner W, Fafera I, Zidek W: Plasma and
intracellular Mg++ concentrations in pre-eclampsia. J Hypertens 8:303-306,199O 4. Flink EB: Nutritional aspects of magnesium metabolism. West J Med 133:304-312,198O 5. Abraham GE, Grewal H: Total dietary program emphasizing magnesium instead of calcium. J Reprod Med 35:503-507,199O
200
6. Okayama H, Aikawa T, Okayama M, et al: Bronchodilating effect of intravenous magnesium sulfate in bronchial asthma. JAMA 257:1076-1078,1987 7. Sutton DN, Tremlett MR, Woodcock TE, Nielsen MS: Management of autonomic dysfunction in severe tetanus: The use of magnesium sulphate and clonidine. Intens Care Med 16:75-80, 1990 8. Kass IS, Cottrell JE, Chambers G: Magnesium and cobalt, not nimodipine, protect neurons against anoxic damage in the rat hippocampal slice. Anesthesiology 69:710-715, 1988 9. James MFM, Beer RE, Esser JD: Intravenous magnesium sulfate inhibits catecholamine release associated with tracheal intubation. Anesth Analg 68:772-776,1989 10. James MFM, Huddle KRL, Owen AD, Van der Veen BW: Use of magnesium sulphate in the anaesthetic management of pheochromocytoma in pregnancy. Can J Anaesth 35:178-182, 1988 11. Resnick LM, Gupta RK, Gruenspan H, et al: Hypertension and peripheral insulin resistance. Am J Hypertens 3:373-379, 1990 12. AItura BM: Ischemic heart disease and magnesium. Magnesium 7:57-67, 1988
DONALD C. FINLAYSON
13. Kafka H, Langevin L, Armstrong PW: Serum magnesium and potassium in acute myocardial infarction. Arch Intern Med 147:465-469, 1987 14. Harris MNE, Crowther A, Jupp RA. Aps C: Magnesium and coronary revascularization. Br J Anaesth 60:779-783, 1988 15. Gambling DR, Birmingham CL, Jenkins LC: Magnesium and the anaesthetist. Can J Anaesth 35:644-654, 1988 16. Fry CH, Hall SK, Blatter LA, McGuigan JAS: Analysis and presentation of intracellular measurements obtained with ionselective microelectrodes. Exp Phys 75:187-198, 1990 17. Aglio LS, Stanford GS, Maddi R, et al: Hypomagnesemia is common following cardiac surgery. J Cardiothorac Vast Anesth 5:201-208,199l 18. Schwieger IM, Kopel ME, Finlayson DC: Magnesium and postoperative dysrhythmias in patients after cardiac surgery. Presented at the 11th Annual Meeting of the Society of Cardiovascular Anesthesiologists, Seattle, WA, April 1989 19. Turlapaty PDMV, Altura BM: Magnesium deficiency produces spasms of coronary arteries: Relationship to etiology of sudden death ischemic heart disease. Science 208:198-200, 1980
Cardiothoracicand Vascular Anesthesia JUNE 1991
VOL 5, NO 3
EDITORIAL Magnesium:
Its Time Has Come
HYSIOLOGISTS HAVE known of the importance of magnesium to the body for many years. Clinicians ignored them. Zwillinger reported the use of magnesium salts for the treatment of dysrhythmias in 1935.’ Clinicians ignored this as well. Magnesium remained a drug almost exclusively the property of obstetricians2.3 and nutritionists.4 Over the past decade there has been a reawakening of interest and many studies have been carried out to elucidate its role in a variety of disease states. These have ranged from osteoporosis in the postmenopausal woman,’ to asthma,” tetanus,’ central nervous system injury,8 intubation9 hypertension with pheochromocytoma,“’ insulin resistance,” and dysrhythmias in the patient with cardiac disease,‘* including those after myocardial infarction” and cardiac surgery.14 Review articles are beginning to appear in the anesthesia literature,” demonstrating that some knowledge of the activities of this divalent cation might be useful to the practicing clinician, and that more frequent measurement and use of magnesium therapeutically might be helpful to our patients-even those outside the obstetrical units. The increased level of interest might even heighten the efforts to produce a clinically useable ion-selective electrode for use in a stat laboratory.‘6 The study by Aglio et al” in this issue of the JOURNAL speaks to the changes in serum magnesium levels after cardiac surgery and represents another of the Chernow group’s investigations of the significance of changes in magnesium in various surgical settings. They demonstrated that low magnesium levels were common preoperatively. In my experience this is a finding often associated with diabetes, and diuretic or alcohol use, conditions common in this population. Hypomagnesemia also occurred in the majority of patients postoperatively. Other groups have made similar observations. Their study has broadened our understanding of magne-
P
sium homeostasis by including determination of ultrafilterable magnesium, parathyroid hormone, and fatty acids, but might have benetitted from observations carried further into the postoperative period to better delineate the time frame of presumed risk. Serum values for total magnesium have returned to normal between the second and third postoperative days in our experience. Despite the lack of a prolonged study, their information is useful in assessing the significance and limitations of the total magnesium concentration. They point out, correctly, that the ultrafilterable fractions may be a more useful way to assess magnesium status, because ionized levels are impossible to determine, and, as is the case with calcium, are probably impossible to assess indirectly from pH and protein concentrations. The implications for therapy are obvious. Hypomagnesemia is common after coronary artery bypass and other types of cardiac surgery. As has been the case with potassium for many years, regular determination of magnesium blood levels and its administration prophylactically in the perioperative period appear to be beneficial in the control of ectopy_‘8 Further, it may be useful in the elimination of perioperative coronary artery spasm.” It is a measurement and a therapy whose time has come, and with more studies like this, appears well on the way to becoming a standard of care in patients with cardiac disease in the surgical setting. Donald C. Finlayson, MD, FRCP(C)
Clinical Professor of Anesthesiology Medical College of Georgia Augusta, GA Director, Divisions of Cardiothoracic Anesthesia and Critical Care Medicine Georgia Baptist Medical Center Atlanta, GA
REFERENCES 1.
Zwillinger L: Uber die magnesiumwirkung auf das herz. Klin
Wehnscher 14:1429-1433,1935 2. Lee ML, Todd HM, Bowe A: The effects of magnesium sulphate infusions on blood pressure and vascular responsiveness during pregnancy. Am J Obstet Gynecol149:705-708,1984 3. Kisters K, Niedner W, Fafera I, Zidek W: Plasma and
intracellular Mg++ concentrations in pre-eclampsia. J Hypertens 8:303-306,199O 4. Flink EB: Nutritional aspects of magnesium metabolism. West J Med 133:304-312,198O 5. Abraham GE, Grewal H: Total dietary program emphasizing magnesium instead of calcium. J Reprod Med 35:503-507,199O
200
6. Okayama H, Aikawa T, Okayama M, et al: Bronchodilating effect of intravenous magnesium sulfate in bronchial asthma. JAMA 257:1076-1078,1987 7. Sutton DN, Tremlett MR, Woodcock TE, Nielsen MS: Management of autonomic dysfunction in severe tetanus: The use of magnesium sulphate and clonidine. Intens Care Med 16:75-80, 1990 8. Kass IS, Cottrell JE, Chambers G: Magnesium and cobalt, not nimodipine, protect neurons against anoxic damage in the rat hippocampal slice. Anesthesiology 69:710-715, 1988 9. James MFM, Beer RE, Esser JD: Intravenous magnesium sulfate inhibits catecholamine release associated with tracheal intubation. Anesth Analg 68:772-776,1989 10. James MFM, Huddle KRL, Owen AD, Van der Veen BW: Use of magnesium sulphate in the anaesthetic management of pheochromocytoma in pregnancy. Can J Anaesth 35:178-182, 1988 11. Resnick LM, Gupta RK, Gruenspan H, et al: Hypertension and peripheral insulin resistance. Am J Hypertens 3:373-379, 1990 12. AItura BM: Ischemic heart disease and magnesium. Magnesium 7:57-67, 1988
DONALD C. FINLAYSON
13. Kafka H, Langevin L, Armstrong PW: Serum magnesium and potassium in acute myocardial infarction. Arch Intern Med 147:465-469, 1987 14. Harris MNE, Crowther A, Jupp RA. Aps C: Magnesium and coronary revascularization. Br J Anaesth 60:779-783, 1988 15. Gambling DR, Birmingham CL, Jenkins LC: Magnesium and the anaesthetist. Can J Anaesth 35:644-654, 1988 16. Fry CH, Hall SK, Blatter LA, McGuigan JAS: Analysis and presentation of intracellular measurements obtained with ionselective microelectrodes. Exp Phys 75:187-198, 1990 17. Aglio LS, Stanford GS, Maddi R, et al: Hypomagnesemia is common following cardiac surgery. J Cardiothorac Vast Anesth 5:201-208,199l 18. Schwieger IM, Kopel ME, Finlayson DC: Magnesium and postoperative dysrhythmias in patients after cardiac surgery. Presented at the 11th Annual Meeting of the Society of Cardiovascular Anesthesiologists, Seattle, WA, April 1989 19. Turlapaty PDMV, Altura BM: Magnesium deficiency produces spasms of coronary arteries: Relationship to etiology of sudden death ischemic heart disease. Science 208:198-200, 1980
