It is clear that patient factors such as age and comorbidity burden are primary predictors of new-onset chronic kidney disease following surgical management of kidney cancer. In addition, there are a number of perioperative factors which may affect kidney function. These have generally been overlooked in the past due to difficulty in collecting data.
The aim of this study was to retrospectively evaluate perioperative factors which may have influenced kidney function after surgery – particularly factors which can mediate prerenal acute kidney injury (AKI), which is the most likely cause of inadvertent kidney damage in the surgical setting.1 In particular, intraoperative blood pressure and perioperative hydration status were assessed, as these can both feasibly induce prerenal AKI due to impaired renal perfusion.
Our study determined that, although intraoperative hypotension was not associated with postoperative AKI following surgery, preoperative dehydration was significantly associated with this outcome. Although dehydration is known to be a risk factor for AKI in a range of clinical settings, this is the first report which has linked preoperative dehydration to worse postoperative kidney function in patients who are being managed surgically for kidney tumours.
When considering the clinical significance of this finding, a number of positions could be considered. AKI is a well-defined end-point based on international guidelines2 and is associated with future risk of chronic kidney disease (CKD),3 however, it is not clear whether AKI in patients who are dehydrated before surgery is associated with long-term renal impairment or simply present as a transient and reversible phenomenon. For those patients with pre-existing kidney damage, the loss of functional nephrons coupled with a global acute injury may have greater implications for future risk of CKD than for patients with normal kidneys. Consequently, the number needed to treat for any intervention aimed at reducing preoperative dehydration to improve long-term kidney function is likely to be quite high.
This highlights the crux of the issue, namely, whether perioperative measures to optimise renal function for ablative renal surgery are necessary in the absence of evidence that this will improve long-term outcomes. It is the view of the authors that, because of the simplicity, low-cost, and low-risk nature of preoperative oral hydration protocols, this course of action is reasonable in the absence of any clinical contraindication. For the purposes of harm minimisation, existing evidence-based preoperative guidelines should be adhered to. 4
Written by: Robert J Ellis and Simon T Wood, Centre for Kidney Disease Research, University of Queensland and Princess Alexandra Hospital, Brisbane, Australia
- Ellis RJ, Del Vecchio SJ, Kalma B, et al. Association between preoperative hydration status and acute kidney injury in patients managed surgically for kidney tumours. Int Urol Nephrol. 2018; 50(7): 1211-1217.
- Kidney Disease: Improving Global Outcomes AKI Workgroup. KDIGO clinical practice guidelines for acute kidney injury. Kidney Int Suppl. 2012; 2: 1-138.
- Cho A, Lee JE, Kwon GY, et al. Post-operative acute kidney injury in patients with renal cell carcinoma is a potent risk factor for new-onset chronic kidney disease after radical nephrectomy. Nephrol Dial Transplant. 2011; 26: 3496-501.
- Smith I, Kranke P, Murat I, et al. Perioperative fasting in adults and children: guidelines from the European Society of Anaesthesiology. Eur J Anaesthesiol. 2011; 28: 556-69.