ORLANDO, FL USA (UroToday.com) - It is generally understood that most nephrons make a very strong recovery from ischemic insult. Several recent works, however, has suggested that poorly functioning kidneys are not as resistant to ischemic insult, and recover less completely when compared to strongly functioning kidneys. In this study from the Cleveland Clinic, presented by Dr. Maria Carmen Mir, the impact of surgical intervention on renal function among patients across several strata of preoperative eGFR was evaluated.
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In order to mitigate the effect of parenchymal loss, they recorded renal parenchymal volume before and after surgery. The recovery of nephron function was defined as the percentage of GFR preserved over the percentage of parenchymal volume preserved. Thus, if an individual was found to have 80% of their preoperative renal function after removal of 80% of renal parenchyma, their recovery of nephron function was 100%.
They evaluated 122 patients undergoing partial nephrectomy in their analysis. To be included, patients had to have adequate studies performed, including computed tomography (CT), and serum creatinine within 2 months prior to surgery and for 4-12 months, postoperatively. Patients with a contralateral kidney underwent renal scans to isolate the impact and recovery on the treated kidney.
Ultimately, they found that "recovery of nephron function was similar for all strata of preoperative eGFR in the operated kidney…even in the limited warm ischemia subgroup." They performed additional analysis between patients receiving warm and cold ischemia, and found that overall recovery of nephron function was 100.7% in the cold ischemia subgroup and 93% in the limited warm ischemia subgroup.
They concluded that recovery from ischemia was strong in all groups, and that even poorly functioning kidneys recovered well, proportionate to the amount of renal parenchyma preserved. It appears that the most important determinant of nephron function recovery is the amount of parenchyma preserved. During the lively discussion following the presentation, Dr. Campbell mentioned that, in their experience, any reduction in vascularized parenchyma, including occlusion to vessels by suture placed during reconstruction, likely has a negative impact on recovery of nephron functioning, adding that it may be more significant than the purported benefit of zero ischemia.
Presented by Maria Carmen Mir at the American Urological Association (AUA) Annual Meeting - May 16 - 21, 2014 - Orlando, Florida USA
Cleveland Clinic, Cleveland, OH USA
Written by Martin Hofmann, MD, University of California (Irvine), and medical writer for UroToday.com