ALTERATIONS IN PLASMA MAGNESIUM CONCENTRATIONS DURING LIVER-TRANSPLANTATION

Plasma magnesium concentrations were monitored during orthotopic liver transplantation. Magnesium supplementation was not given, although in traoperative calcium, potassium, and sodium bicarbonate were given as required. We found that there were significant falls in magnesium conc entration to below our laboratory lower limit of normal, occurring chi efly during the anhepatic phase of surgery. Two patients with hypomagn esemia but normal potassium and calcium ion concentrations developed v entricular extrasystoles. Magnesium is a smooth muscle relaxant, dilat ing coronary arteries and peripheral vessels. It also exerts an antiar rhythmic effect and may have a permissive effect on the actions of cat echolamines. Magnesium supplementation may be indicated during orthoto pic liver transplantation because of the potentially beneficial effect s and to avoid possible deleterious effects of hypomagnesemia. However , magnesium levels need to be monitored to avoid the unwanted side eff ects of hypermagnesemia.