Background: Infrarenal aortic cross-clamping causes renal vasoconstriction. Magnesium may protect against renal deterioration through its vasodilatory properties.
Methods: Thirty patients with normal preoperative renal function undergoing infrarenal aortic cross-clamping for elective aortic surgery received magnesium (4 mmol) or saline into the aorta immediately after aortic cross-clamping and again just before unclamping in a double-blind fashion. Pulmonary artery occlusion pressure was maintained 215 mmHg. Five patients with magnesium were excluded due to need for intravenous nitroglycerine because of myocardial ischaemia during the study.
Results: Postoperative creatinine clearance remained unchanged in both groups. Urinary N-acetyl-beta-D-glucosaminidase excretion increased before and decreased after aortic cross-clamping in both groups. The concentrations of glutathione peroxidase in serum were identical between the two groups.
Conclusions: These data indicate that intra-aortic magnesium had no effect on renal function during or after aortic cross-clamping.