Renal function in patients at risk of contrast material-induced acute renal failure: noninvasive, real-time monitoring.

Real-time changes in renal function were studied in a group of 20 patients at risk of contrast-material-induced acute renal failure during different angiographic procedures. Renal function was evaluated with an ambulatory renal monitor (ARM) after a single injection of the glomerular filtration agent technetium-99m diethylenetriaminepentaacetic acid (DTPA). The ARM was used to continuously monitor the clearance of Tc-99m DTPA activity from the extracellular space in the arm of the patient during angiography. A one-compartment model was used to calculate on-line the rate constant for clearance of Tc-99m DTPA from the extracellular space. Changes in the rate constant were compared with changes in plasma creatinine level measured 1-4 days after angiography. The results showed that the ARM measured rapid changes in renal function during angiography with a resolution time of 5-10 minutes in patients with normal to moderately decreased renal function and 15-20 minutes in patients with severe renal dysfunction. The sensitivity of this technique was superior to that of plasma creatinine level analysis.