NEW YORK (Reuters Health) – In cases of elective partial nephrectomy for localized renal cortical tumors, a warm ischemia time of up to 20 minutes is not associated with clinically relevant loss of renal function subsequently, according to a report in the May issue of the Journal of Urology.

The authors note that partial nephrectomy has traditionally been done using regional hypothermia or keeping the period of warm ischemia to less than 30 minutes, in order to limit ischemic damage. However, it has been suggested that every minute of warm ischemia has a deleterious effect, so some surgeons recommend partial nephrectomy always be performed with hypothermia or without vascular occlusion whenever possible.

However, Dr. Steven C. Campbell, at the Cleveland Clinic, Ohio, and colleagues believe that significant selection bias led to these conclusions. To investigate, they reviewed the records of 1132 patients who underwent partial nephrectomy and who had two functioning kidneys and normal serum creatinine preoperatively.

In this cohort, partial nephrectomy was performed without regional ischemia in 58, with less than 30 minutes of warm ischemia in 809, or with cold ischemia in 265. At latest follow-up at an average of 1.5 years after surgery, the relative decrease in renal function in the three groups was 0.5%, 13% and 11%, respectively, the team reports.

However, tumor size and the amount of parenchyma removed were lowest in the cases without regional ischemia. After adjusting for this, in multivariate analysis the baseline glomerular filtration rate and the percent of parenchyma preserved were strongly associated with subsequent renal function (p0.05), according to the report.

The only significant difference (p<0.02) was in comparing the group without regional ischemia to patients with 21-30 minutes of warm ischemia time, who had a 15% decrease in renal function. Even so, renal failure developed in only 0.4%.

“Adverse renal functional outcomes are rare after elective partial nephrectomy and largely independent of approach, particularly if warm ischemia time remains limited to less than 20 minutes,” Dr. Campbell and colleagues conclude.

They add, “Methods to decrease the detrimental effects of warm ischemia are unlikely to produce clinically significant benefits in most patients with an adequate renal reserve but they have great potential in patients at higher risk for chronic kidney disease after partial nephrectomy.”

Reference:
Limited Warm Ischemia During Elective Partial Nephrectomy has Only a Marginal Impact on Renal Functional Outcomes
J Urol 2011;185:1598-1603.