Acute renal failure in the patient undergoing cardiac operation. Prevalence, mortality rate, and main risk factors.

A total of 775 consecutive patients who survived the first 24 hours after cardiac operation were prospectively studied to assess the prevalence, mortality rate, and main risk factors for development of new acute renal failure. Normal renal function before operation (serum creatinine level less than 1.5 mg/dl) was registered in 734 (94.7%) patients. Of these, 111 (15.1%) showed a postoperative renal complication including 84 (11.4%) classified as renal dysfunction (serum creatinine level between 1.5 and 2.5 mg/dl) and 27 (3.7%) as acute renal failure (serum creatinine level higher than 2.5 mg/dl). The mortality rate was 0.8% in normal patients, 9.5% in patients with renal dysfunction, and 44.4% when acute renal failure developed (p < 0.0001). Indeed, the renal impairment proved to be an independent predictor of mortality (p < 0.001), along with the infective (p < 0.001), gastrointestinal (p < 0.001), and cardiovascular (p < 0.05) complications. Multivariate analysis identified the following variables as independent risk factors for postoperative renal impairment: use of intraaortic balloon pump (p < 0.0001), need for deep hypothermic circulatory arrest (p < 0.005), low-output syndrome (p < 0.005), advanced age (p < 0.005), need for emergency operation (p < 0.025), and low urinary output during cardiopulmonary bypass (p < 0.05). The 41 patients (5.3%) with preoperative renal failure showed a significantly higher morbidity and mortality rate than those without renal complications before operation. We conclude that in patients undergoing cardiac operation without preexisting renal dysfunction the likelihood of severe renal complications is reasonably low, but the associated mortality remains high. A prominent role in the development of postoperative acute renal failure must be recognized for preoperative, intraoperative, and postoperative hemodynamic factors, whereas cardiopulmonary bypass seems to be of lesser importance in this respect.

Effects of a continuous diltiazem infusion on renal function during cardiac surgery.

Thirty-five male patients undergoing coronary artery surgery were studied to investigate renal function during a continuous infusion of the calcium channel blocker diltiazem. All patients had preoperative renal function within normal limits (serum creatinine below 0.133 mmol/L) and were randomly divided into three groups: Control (C), Diltiazem 1 (D1), and Diltiazem 2 (D2). Diltiazem was infused in D1 (1 microgram/kg/min) and D2 (2 micrograms/kg/min) patients throughout surgery and during the following 36 hours. Glomerular function was investigated using the endogenous creatinine clearance while tubular function was assessed by means of water and sodium reabsorption tests, as well as urinary enzyme activity measurements. Hemodynamic monitoring was performed using a pulmonary artery catheter. The glomerular filtration rate of C and D1 patients showed a significant fall during cardiopulmonary bypass (CPB) with respect to the prebypass period and returned to the baseline values only in the postoperative period. A similar change was not observed in D2 patients. The analysis of variance demonstrated that the glomerular filtration rate was significantly higher in Group D2 versus Group C during and after CPB (P = 0.03 and P = 0.04, respectively). Furthermore, after CPB, urinary output was significantly improved in D2 patients, both versus C and D1 patients (P = 0.003), notwithstanding a lower mean arterial pressure in the D2 Group (P = 0.04 v C Group). Tubular function was not influenced by diltiazem infusion. It is concluded that a continuous diltiazem infusion, at a dose of 2 micrograms/kg/min during cardiac surgery, may be useful to prevent a decrease in glomerular function secondary to cardiopulmonary bypass.

[Coronary angiography in two defined populations: Padua and Citadella]. / La coronarografia in due popolazioni definite: a Padova ed a Cittadella.

BACKGROUND: Coronary angiography is an invasive procedure that is relatively expensive and that requires an appropriate indication. METHODS: Utilization rate and the appropriateness of the use of the coronary angiography have been compared in two defined populations, namely residents from the city of Padua (group A), and subjects from the local health unit of Cittadella (group B), who underwent coronary angiography between June 1, 1992 and May 31, 1993. Appropriateness was evaluated both by comparison with the AHA/ACC guidelines and by observation of the outcome following diagnosis one year after the coronary angiogram was performed. RESULTS: One hundred and seventy-one patients in group A and 100 patients in group B underwent coronary angiography: both groups had similar age and sex distribution. Utilization rate was 8 per 10,000 inhabitants in group A, and 10 per 10,000 inhabitants in group B. Appropriate coronary angiography, evaluated by comparison with the AHA/ACC guidelines, was 69.9% in group A and 68% in group B. Coronary angiogram showed at least one stenosis > or = 50% in 133 patients from group A and in 66 patients from group B. These patients were followed up for at least 12 months. Of 13 deaths, 12 occurred as fatal cardiac events, while of the 147 surviving patients who had complete follow-up data, 114 (77%) improved. The outcome was measured through symptoms and stress test. In addition, subjective improvement was measured in group A using the "Nottingham Health Profile". CONCLUSIONS: Criteria of appropriateness for an invasive diagnostic procedure such as coronary angiography, which is a determinant "entry point" for revascularization procedures, is based on common clinical knowledge that may be evolving with time. Based on these data, it seems that the current guidelines could be modified, especially for indications within the setting of myocardial infarction.