Renal protection in the ICU: role of fenoldopam

Introduction

Acute renal failure (ARF) is one of the most common problems of the critical patient, often resulting in acute tubular necrosis following an impairment in renal hemodynamics. Fenoldopam is a selective dopaminergic agonist specific for dopaminergic receptor DA-1 that, provoking an increase in renal blood flow, diuresis and natriuresis, seems to prevent ARF – exerting a nephro-protective effect.

Methods

Patients in the ICU without ARF but at risk of renal damage (sepsis, nephrotoxic drug administration) were recruited. Fenoldopam was administered by intravenous infusion (0.05–0.1 μg/kg/min) for 24 hours. Specific tubular enzymatic biomarkers (β₂-microglobulin, microalbuminuria, retinal binding protein, γGT, alkaline phosphatase, n-acetyl-glucosaminidase) have been dosed in urine before fenoldopam administration (basal value), at the end of the infusion (T1) and 24 hours later (T2). Diuresis, blood creatinine and cystatin C were also measured in the same interval. All data were compared using a t test and logistic regression analysis.

Results

See Figure 1. Of the 23 patients studied, after informed written consent, 10 patients received fenoldopam. At T1 a statistically significant reduction of the tubular biomarkers, cystatin C and creatinine, and an increase in diuresis were found compared with basal. At T2 a nonstatistically significant reduction of γGT and microalbumin and cystatin C associated with an increased urinary output were observed, showing a benefit on kidney function lasting even after 48 hours.

Figure 1

Markers of renal function. NAG, n-acetyl-glucosaminidase; B2M, β₂-microglobulin; Microalb, microalbuminuria; PLR, retinal binding protein; ALP, alkaline phosphatase; GGT, γGT.

Conclusion

Our study shows a significant protective effect of fenoldopam measured by tubular biomarkers after a 24 hour infusion.