A prospective trial assessing the effects of clamp ischemia during partial nephrectomy on renal function, biomarkers, and structure.

Abstract

367 Background: Tolerance of the human kidney to clamp ischemia (CI) during partial nephrectomy (PN) has been considered to be limited to 20–30 min. We determined the utility of new biomarkers for following renal injury in this setting. Methods: 40 patients undergoing open PN without ( N=27, avg clamp time 32.3 min, range 15–53 min., 74% > 30 min.) or with cooling ( N=13 avg clamp 48 min. range 30–61 min.) had biopsies of uninvolved areas of the kidney preclamp, during clamping and 5 min. after clamp release, along with serial measurements of standard renal functional parameters plus measurement of serum cystatin C and NGAL, and of urine NGAL, cystatin C, NAG, LFABP, NGAL, KIM-1 and IL-18. Results: Serum creatinine transiently increased at 24 hours by 21.9±6.4% after warm CI and 27.2±7.9% after cold CI (Ps < .001), but serum cystatin C did not change and plasma NGAL was minimally affected. Urine biomarkers increased irrespective of whether they were factored for creatinine, with particularly large changes in KIM-1 and LFABP, but did not correlate with duration of CI, the change in creatinine at 24 hours, or the use of cold or warm CI. Ultrastructure and staining for actin, phosphotyrosine, B1 integrin, and ICAM-1 showed changes consistent with CI, but much milder than predicted from animal models. Creatinine has remained stable in the patient cohort at up to 18 months of follow-up. Conclusions: The data indicate that the insult to the clamped kidney from 30–60 minutes of CI under conditions of open partial nephrectomy is well tolerated despite increases of urinary biomarkers, which may in part reflect local effects of the surgery itself, expand indications for PN in the management of renal cancers, and support the use of CI as opposed to more complex procedures for PN.