Transcutaneous renal function monitor: precision during unsteady hemodynamics.

OBJECTIVE: Hospital acquired renal dysfunction, most commonly caused by renal hypoperfusion, dramatically increases mortality in intensive care patients. Glomerular filtration rate (GFR) is rapidly altered during renal hypoperfusion, and a more rapid means of GFR measurement may prompt institution of renal-specific therapy. We hypothesized that a transcutaneous renal function monitor can rapidly and accurately assess acute changes in GFR within a time frame much shorter than the 2-4 hours currently available.
METHODS: The study design was a prospective determination of the capability to measure GFR transcutaneously. In three different studies, concurrent transcutaneous measurement of GFR, using the rate of disappearance of 99mTc-diethylenetriaminepentaacetic acid (DTPA), was compared by correlation and standard deviation (SD) to reference standards of DTPA plasma clearance, serum inulin clearance, or serum creatinine.
RESULTS: Continuous transcutaneous clearance (TC) measurement correlated with standard DTPA plasma clearance techniques (r = 0.93). Acute pharmacologically induced changes in GFR are detectable by TC measurement within 12-20 min, a time interval significantly affected by the data acquisition interval. Excess patient movement in the ICU patients created clearance artifacts in 50% of clearance traces. Retrospective analysis of ICU patient data reveal TC measurements are 93% specific and 92% sensitive for serum creatinine levels in critically ill patients.
CONCLUSIONS: TC monitoring provides prompt indication of directional changes in GFR and may provide the clinician warning of inadequate resuscitation. Prospective analysis of the specificity, sensitivity, and TC guided renal-specific resuscitation is needed.