Background and objective: A variable incidence rate of renal dysfunction (3-35%) after cardiac surgery with cardiopulmonary bypass has been reported. The aim was to define the typical pattern of renal dysfunction that follows coronary surgery with cardiopulmonary bypass using albumin, immunoglobulin (IgG), alpha1-microglobulin and beta-glucosaminidase (beta-NAG) excretion as indicators.
Methods: Twenty patients with preoperative normal renal function, defined by plasma creatinine, creatinine clearance, fractional excretion of sodium and renal excretion of proteins, undergoing elective myocardial revascularization surgery with cardiopulmonary bypass, were prospectively studied. Variables recorded were demographic and haemodynamic variables, duration of cardiopulmonary bypass and aortic clamping, intra- and postoperative urine output, plasma creatinine concentration, creatinine clearance and excretion of sodium, albumin, IgG, beta-glucosaminidase (beta-NAG), and alpha1-microglobulin. Measurements were made preoperatively, immediately before and then during and immediately after cardiopulmonary bypass, and again at 1, 24, 72 h, 7 and 40 days following surgery.
Results: Albumin and IgG excretion rose significantly during cardiopulmonary bypass (P < 0.05), remaining at these levels at 24 h postoperatively. An increase of alpha1-microglobulin and beta-NAG concentrations was observed during cardiopulmonary bypass (P < 0.05), which were maintained until the seventh postoperative day and remained elevated in some patients at the 40th postoperative day. This correlated with preoperative diabetes mellitus (P < 0.001), low cardiac output after cardiopulmonary bypass (P < 0.001) and the duration of stay in the intensive care unit (P < 0.001).
Conclusions: The pattern of renal dysfunction after cardiopulmonary bypass for myocardial revascularization is characterized by temporary renal dysfunction at both glomerular and tubular levels with an onset within 24 h of surgery and which lasts between 24 h and 40 days, respectively, following surgery.