[Perioperative modifications in kidney function]

Impaired microcirculation and tubule injuries explain the changes in kidney function during and after surgery. Surgery is a risk factor for acute renal failure, the incidence of which ranges from 0.8% to 40%, depending on the kind of surgery. Mortality due to perioperative acute renal failure ranges from 17% to 60%, depending on the kind of surgery. For almost 10 to 20% of survivors, acute renal failure becomes chronic. Of the various definitions of acute renal failure, the RIFLE classification(risk of renal dysfunction, injury to the kidney, failure of kidney function, loss of kidney function, end-stage kidney disease)is a consensus definition for predicting hospital mortality. Preoperative renal function was based on serum creatinine and creatinine clearance, calculated with either the Cockcroft and Gault or modification of diet in renal disease (MDRD) formula. Predictors of postoperative acute renal failure include: previous renal dysfunction (most predictive), age older than 56 years, peripheral vascular occlusive disease, chronic obstructive pulmonary disease, congestive heart failure, hypertension and diabetes mellitus, body mass index over 32, use of a vasopressor infusion and diuretic administration, emergency or major surgery, and liver disease. Biomarkers for acute kidney injury are useful for diagnosis of early renal dysfunction. The most promising of these isneutrophil gelatinase-associated lipocalin(NGAL). Renal protection consists in maintaining an optimal blood volume and cardiac output. Nephrotoxic agents always must be removed.