Ischemia Techniques in Nephron-sparing Surgery: A Systematic Review and Meta-Analysis of Surgical, Oncological, and Functional Outcomes

Abstract

ContextThe optimal ischemia technique at partial nephrectomy (PN) for renal masses is yet to be determined. ObjectiveTo summarize and analyze the current evidence about surgical, oncological, and functional outcomes after different ischemia techniques (cold, warm, and zero ischemia) at PN. Evidence acquisitionA computerized systematic literature search was performed by using PubMed (MEDLINE) and Science Direct. Identification and selection of the studies were conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-analysis (PRISMA) criteria. Outcomes of interest were estimated blood loss (EBL), overall complications, positive surgical margins, local tumor recurrence, and renal function preservation. Meta-analysis and forest-plot diagrams were performed. Overall pooled estimates, together with 95% confidence intervals (CIs), of the incidence of all parameters were obtained using a random effect model (RE-Model) on the log transformed means (MLN), proportion, or standardized mean change, as deemed appropriate. Evidence synthesisOne hundred and fifty-six studies were included. No clinically meaningful differences were found in terms of EBL after cold (mean: 215.5; 95% CI: 154.2–276.8m), warm (mean: 201.8; 95% CI: 175.0–228.7ml), or zero (mean: 261.2; 95% CI: 171.0–351.3ml) ischemia technique. Overall, postoperative complications were recorded in 14.1% (95% CI: 6.7–27.4), 11.1% (95% CI: 10.0–12.3), and 9.7% (95% CI: 7.7–12.2) of patients after cold, warm, and zero ischemia (p<0.01), respectively. Positive surgical margins were recorded in 4.8% (95% CI: 1.9–10.9), 4.0% (95% CI: 3.4–4.8), and 5.6% (95% CI: 3.1–9.8) of patients after cold, warm, and zero ischemia (p<0.01), respectively. Local recurrence was recorded in 3.2% (95% CI: 1.9–5.2) and 3.1% (95% CI: 0.7–11.5) of patients after warm and zero ischemia (p<0.01), respectively. The log2 of estimated glomerular filtration ratio mean changes were–1.37 (95% CI:–3.42 to 0.68),–1.00 (–2.04 to 0.03), and–0.71 (–1.15 to–0.27) ml/min after cold, warm, and zero ischemia, respectively. Low level of evidence, retrospective nature of most of included studies, a high risk of selection bias, and heterogeneity within included studies limited the overall quality of the analysis. ConclusionsThe effect of ischemia technique at PN is still debatable and subject to confounding by several factors, namely, patients’ selection criteria, surgical technique used, and percentage of functional parenchyma spared during surgery. These confounders bias available evidence and were addressed by only a small part of available studies. Unfortunately, the overall quality of literature evidences and the high risk of selection bias limit the possibility of any causal interpretation about the relationship between the ischemia technique used and surgical, oncological, or functional outcomes. Thus, none of the available ischemia technique could be recommended over the other. Patient summaryThe present analysis shows that none of the available ischemia techniques, namely, cold, warm, or zero ischemia, is universally superior to the others, and other factors play a role in the surgical outcome.