Creatinine clearance of early detection of posttraumatic renal dysfunction

Acute renal failure develops insidiously in the presence of normal urine output and vital signs. A prospective study was carried out to find whether renal impairment can be detected in the immediate postoperative period and to determine the renal function test best predicting the development of renal dysfunction. Forty patients with multiple trauma who required more than 10 units of blood and had a systolic blood pressure less than 80 mmHg on admission were studied. Creatinine clearance (Ccr), free-water clearance (CH2O), fractional excretion of Na+, blood urea nitrogen (BUN), urine flow rate, and vital signs were measured and compared in seven patients who developed renal dysfunction within a week of trauma (Group 1) and 33 patients who maintained normal renal function (Group 2). In all Group 1 patients Ccr remained less than 25 ml/min and CH2O greater than -15 ml/h for 6 h following surgery. None of the Group 2 patients had Ccr less than 25 ml/min for longer than 4 h following surgery. However, CH2O values were greater than -15 ml/h in 15 of the 33 Group 2 patients during the first 24 postoperative hours. Ccr values less than 25 ml/min were present, despite normal urine flow rate and blood pressure, in patients who subsequently developed renal dysfunction. Patients who have Ccr values less than 25 ml/min within 6 h following trauma and surgery may develop renal dysfunction, and some of them may proceed to acute renal failure. CH2O was not as good a predictor of development of renal dysfunction as Ccr.