NONINVASIVE, REAL-TIME MONITORING OF RENAL-FUNCTION DURING CRITICAL CARE

The inadequacy of the current techniques to monitor renal function has been the most important limitation for determining the appropriatenes s of a particular form of therapy in acute renal failure. The objectiv e of this study was to determine the advantage offered by a new method of accurate, noninvasive, and realtime monitoring of renal function d uring the critical care of patients. A radiation detector attached to a miniature data logger was used to monitor the clearance of the glome rular filtration agent Tc-99m-diethylene triamine pentaacetic acid fro m the extracellular space in 20 patients admitted into an intensive ca re unit. The rate constant for this clearance was calculated online fr om 5-min epoch lengths of activity versus time. Changes in this consta nt were compared with changes in plasma creatinine and timed urine out put. The results showed that the ambulatory renal monitor could accura tely measure rapid changes in renal function during the critical care of patients who are at risk of acute renal failure with a resolution t ime of 5 to 10 min. The sensitivity and specificity of the technique a re also superior to plasma creatinine and urine output because it can detect minimal and transient changes in renal function that otherwise may have gone undetected by these parameters. This unique approach sho uld allow for the immediate institution and/or adjustment of the appro priate therapeutic procedure to preserve or improve the renal function .