Introduction & Objective : Despite the known nephrotoxicity of gentamicin, many societies (including the American Urological Association in 2008) have published guidelines recommending a single perioperative gentamicin dose of 5 mg/kg for antimicrobial prophylaxis during urologic prosthetic surgery. This recommendation is based on the theoretical renal safety and increased antimicrobial activity of a single large dose. The goal of our investigation was to identify rates of acute kidney injury (AKI) in urologic prosthetic surgery both before and after adoption of weight-based gentamicin dosing.
We performed a single-institution retrospective study of all patients receiving perioperative gentamicin during implant, revision, or explant of penile prostheses or artificial urinary sphincters between 2000 - 2017. Patient characteristics and perioperative outcomes were identified. Patients with available pre- and postoperative (≤ 7 days) creatinine values were included. AKI was defined by Kidney Disease: Improving Global Outcomes (KDIGO) criteria. Comparative analyses were performed between patients receiving standard-dose gentamicin and weight-based gentamicin.
Results : Of 415 urologic prosthetic surgeries performed during the study period, 124 met inclusion criteria with paired pre- and postoperative creatinine values. Sixty-seven received standard-dose gentamicin and 57 received weight-based gentamicin (mean dose 1.0 ± 1.4 vs. 3.7 ± 1.4 mg/kg, p < 0.05). There were no significant differences in preoperative renal function or various comorbidities between groups; however, the standard-dose group was slightly younger (mean age 60.5 ± 8.5 vs. 64.0 ± 7.4 years, p < 0.05), and comprised more explant cases (13.4 vs. 1.8%, p = 0.02) than the weight-based group. Two of 67 (3.0%) in the standard-dose group vs. 9 of 57 (15.8%, p = 0.02) in the weight-based group developed AKI (figure 1). Device infection rate was similar between standard-dose and weight-based groups (5.2 vs. 5.3%, p = 1.00).
Conclusions : Our data suggest weight-based perioperative gentamicin dosing may be associated with an increased risk of AKI, without noticeably improving infection rates. Weight-based dosing may warrant closer perioperative monitoring of renal function, and merits larger investigations to determine risks and benefits.