Parenchymal volume and functional recovery after clamped partial nephrectomy: potential discrepancies

Area of Science:

• Nephrology
• Surgical Oncology
• Medical Imaging

Background:

• Parenchymal-volume-analysis (PVA) is considered superior to nuclear-renal-scans (NRS) for assessing split-renal-function (SRF).
• The impact of ischemia during partial nephrectomy (PN) on PVA accuracy for functional outcomes is not fully understood.

Purpose of the Study:

• To evaluate how ischemia during partial nephrectomy (PN) affects the accuracy of parenchymal-volume-analysis (PVA) in estimating functional outcomes.
• To compare PVA and nuclear-renal-scans (NRS) derived split-renal-function (SRF) estimates under varying ischemia conditions during PN.

Main Methods:

• Retrospective analysis of 437 partial nephrectomy (PN) patients with pre/postoperative NRS and cross-sectional imaging.
• Evaluation of differences between NRS and PVA-derived ipsilateral SRF estimates in warm ischemia (WI) and cold ischemia subgroups.
• Assessment of the relationship between ischemia time and PVA/NRS discordance using linear and segmented-regression.

Main Results:

• Preoperative PVA and NRS-based SRF estimates showed high correlation (r=0.94).
• Post-PN, PVA estimates were significantly higher than NRS in warm ischemia (WI) (44% vs. 42%, P=0.001), particularly after 24 minutes of WI (P=0.04).
• No significant discordance was observed with hypothermia or limited WI; prolonged WI led to a 2-3 fold greater functional decline than PVA alone indicated.

Conclusions:

• PVA accurately predicts SRF preoperatively and assesses functional outcomes with hypothermia or limited WI.
• Prolonged WI (>24 minutes) during PN leads to increasing discordance between PVA and actual renal function.
• Avoidance of prolonged WI is recommended for patients with solitary kidneys or significant chronic kidney disease.