The association between modifiable perioperative parameters and renal function after nephrectomy

Objective: To evaluate the association between intraoperative anaesthetic parameters, primarily intraoperative hypotension, and postoperative renal function in patients undergoing nephrectomy. Patients and Methods: We reviewed data from 3240 consecutive patients who underwent nephrectomy between 2010 and 2018. Anaesthetic parameters evaluated included duration of hypotension, tachycardia, hypothermia, volatile anaesthetic use and mean arterial pressure in the post-anaesthesia care unit. Outcomes included acute kidney injury (AKI) and estimated glomerular filtration rate (eGFR) within the first year after nephrectomy. Associations between anaesthetic parameters and outcomes were evaluated with multivariable logistic regression and generalised estimating equation, respectively, adjusted for predictors of renal function after nephrectomy. Results: Before nephrectomy, 677 (21%) patients had moderate–severe chronic kidney disease. A quarter of patients (n = 809) had postoperative AKI and 35% (n = 746) had Stage ≥3 chronic kidney disease 12-months after surgery. Only 12% of patients (n = 386) had >5 min of intraoperative hypotension. While not statistically significant, longer duration of intraoperative hypotension was associated with slightly higher rates of AKI (odds ratio [OR] per 10-min 1.14, 95% confidence interval [CI] 0.98, 1.32). Prolonged hypothermia was associated with increased rate of AKI (OR per 10-min 1.02, 95% CI 1.00, 1.04), and decreased eGFR (change in eGFR per 10-min −0.19, 95% CI −0.27, −0.12); however, these results have limited clinical significance. Conclusions: Under current practice, intraoperative anaesthetic parameters are tightly maintained, restricting the significance of their effect on postoperative renal function. Future studies should evaluate whether haemodynamic parameters during the early postoperative period, when they are monitored less frequently, are associated with renal functional outcome.