Moving away from mannitol infusion for partial nephrectomy: has this altered renal function?

In recent years, research has questioned the theorized renal-protective value of mannitol infusion during partial nephrectomy. This study considers whether the cessation of routine mannitol administration has shown any benefit or detriment to patients in the contemporary era. We retrospectively reviewed a multi-institution database for an association between mannitol administration and subsequent renal function during follow-up. These patients were assessed for de novo stage III chronic kidney disease (CKD III) and followed with estimated glomerular filtration rate (eGFR). Statistical analysis included Mann-Whitney-U and Chi-squared tests for comparing baseline and perioperative variables with postoperative outcomes. eGFR changes were evaluated with a mixed-effects linear regression model. Nine hundred and fifteen patients were identified whose operative reports or surgeons' treatment algorithms explicitly described whether or not mannitol was administered. 667 (73%) did not receive mannitol. There were no differences in demographics, age, Charlson comorbidity index, nephrometry score, tumor size, grading, or baseline eGFR from those who received mannitol. Ischemia time and operative time appeared slightly longer with mannitol use. Patients were followed for a median of 5 months (IQR 0.5-19 months), during which mannitol use was associated with an increase in de novo CKD III (14% v. 9%, p = 0.041) and minimally worsened median eGFR on final follow-up (72.82 v. 76.06, p = 0.039). Our analysis of partial nephrectomy patients indicates that mannitol administration likely confers no short- or long-term renal benefit. Mannitol may be used at the surgeon's discretion, but if it prolongs surgery time or ischemia time, it may in fact be detrimental to outcomes.