[Acute renal failure in patients undergoing cardiac surgery]

Acute renal failure (ARF) is an unusual and severe complication which may occur in patients following cardiac surgery. The incidence of ARF is from 1% to 15% (according to some authors up to 40%). The ARF, occurring in the postoperative period and requiring dialysis is an important risk factor for early mortality, while the overall mortality due to this complication is as high as 40% (40% to 90%).

The aim of this study was to assess the incidence of ARF in patients undergoing cardiac surgery at our hospital from January 1, 2001 to June 1, 2002 and to compare it with the data obtained at the same institution and published 17 years ago.

A total of 290 patients undergoing cardiac surgery were analyzed, 71 (24.5%) female and 219 (75.5%) male, mean age 61.1 (range 17-81) years. Exclusion criteria were death within a few hours of surgery and need of chronic hemodialysis prior to surgery. ARF was defined as doubling of serum creatinine (sCr) concentration with preoperative sCr concentration below 130 micromol/L, or sCr increase by 100 or more micromol/L after cardiac surgery. Age, sex, type of surgery, preoperative sCr and preoperative risk factors (hypertension, diabetes mellitus, hyperproteinemia, pulmonary disease, peripheral vascular disease, central vascular disease) as well as complications occurring during the operation and their influence on ARF were analyzed. The incidence of ARF, therapy and mortality were also analyzed.

Ischemic cardiac disease was present in 236 (81%) and valvular disease in 41 (14%), ventricular or atrial septal defect in 6 (2%), thoracic aortic aneurysm in 3 (1%), patent ductus arteriosus in 2 (0.7%) patients, and pericardial tumor and penetrant pericardial injury in 1 (0.36%) patient each. Arterial hypertension was present in 199 (68.6%), hyperlipoproteinemia in 194 (66.8%), diabetes mellitus in 76 (26.2%), cardiac arrhythmias in 39 (13.45%), cerebrovascular diseases in 32 (11.0%) previous, renal diseases in 25 (8.6%), chronic obstructive lung disease in 23 (7.9%) patients, peripheral vascular disease by 19 (6.6%) patients, thyroid disease by 8 (3.1%), and malignant disease in 5 (7.1%) patients. Renal function according to sCr was as follows: <79 micromol/L in 90 (31.0%), 80 to 99 micromol/L in 124 (42.7%), and 100-129 micromol/L in 58 (20%), 130-159 in 10 (3.4%), and >160 micromol/L in 4 (1.4%) patients. ARF developed in 8 (2.1%) patients who had undergone cardiac surgery. Among them, only one (0.3%) patient needed dialysis treatment (hemodialysis and continuous venovenous hemofiltration). There were no differences in sex distribution between the patients who developed ARF and those who did not. The patients who developed ARF were older, mean age 65.7 years. Most of the patients with ARF suffered from hypertension, diabetes mellitus and hyperlipoproteinemia. Seventy-five percent of patients who developed ARF had some kind of "surgical" complications: postoperative bleeding with developing hemorrhagic shock, myocardial infarction during the operation, or acute abdomen after the operation.

The incidence of ARF in patients undergoing cardiac surgery was low (2.1%). The incidence of severe ARF (which must be treated with dialysis) was 0.3%. We compared the data obtained at our hospital with those obtained 17 years ago and found a reduction in the incidence of severe ARF after cardiac surgery (0.3% vs. 4%).