Perioperative renal failure: Predictor

Acute kidney failure occurs in up to 5% of all hospitalized patients and is associated with increased length of stay, cost, and mortality. Seven independent preoperative predictors have been identified in patients with previously normal renal function (CC >80 ml/min) who developed acute renal failure following surgery. These predictors were identified by a single center prospective study that included 15,102 patients who underwent noncardiac surgery between 2003 – 2006. The incidence of post-operative renal function in this group was 0.8%, which the authors report as consistent with that reported in general hospitalized patients (ranging from 1% to 5%). Acute Renal Failure in this study was defined as a calculated creatinine clearance of 50ml/min or less within first 7 postoperative days. The study was published in 2007 Anesthesiology.

Risk factors for AKF in noncardiac surgery patients:

• Age >59
• Emergent Surgery – as defined by anesthesiologist documentation of ASA physical status code
• Chronic Liver Disease
• BMI > 32
• High Risk Surgery was defined as intrathoracic, intraperitoneal, suprainguinal vascular, and other surgeries with the potential for large fluid shifts, such as multilevel spine fusions, intracranial aneurysm clippings, transhiatal esophagectomy, and pelvic exenteration)
• Peripheral Vascular Disease
• COPD necessitating bronchodilator therapy

Preoperative predictors in cardiac surgery patients that have been previously recognized include:

• Female sex
• Chronic obstructive pulmonary disease
• Insulin-dependent diabetes mellitus
• Congestive heart failure
• Left ventricular ejection fraction <35%
• Prior surgery
• Emergency surgery
• Pre-operative intra-aortic balloon pump
• Pre-operative creatinine value above 1.2 mg/dl

Intraoperative Risk Factors during Cardiac Surgery:

• Use and duration of exposure to cardiopulmonary bypass (CPB)
• Use of intra-aortic balloon pump
• Deep hypothermic circulatory arrest
• Low cardiac output syndrome
• Low urine output during CPB
• Need for vasopressors before CPB
• Number of blood transfusions during surgery