The levels of zinc, copper, calcium and magnesium in serum and urine after heart-valve replacement. Effects of oxygenator type and postoperative parenteral nutrition.

We studied the effects of mitral or aortic valve-replacement operations with cardiopulmonary bypass on the levels of zinc, copper, calcium, and magnesium in serum and urine in 23 patients. The specimens of blood and urine were taken preoperatively and on the second and fifth postoperative days. There were remarkable decreases in serum levels on the second postoperative day of all four bioelements in all patients compared to the preoperative levels. At the same time there were also clear decreases of calcium and magnesium in urinary excretions. The urine zinc and copper excretion showed no big variations during the three study periods. On the fifth postoperative day, serum magnesium levels increased in all patients in spite of increased urine excretion. Serum calcium levels decreased on the fifth day further and urine excretion increased again. Serum copper levels increased slightly on the fifth postoperative day compared to the second postoperative day. At the same time serum zinc concentrations increased only in the patients who had parenteral nutrition (approximately 40 kcal per kg of body weight per day) for 4 postoperative days. The effect on zinc levels was the only difference in parameters between patients given conventional fluid therapy with 5% glucose solution or parenteral nutrition with 30% glucose, amino acid, and fat emulsion regimen. There were no differences in the bioelements between patients perfused with bubble or membrane oxygenators.