Perioperative Fluid Management and Renal Protection in Cytoreductive Surgery with Hyperthermic Intraperitoneal Chemotherapy (CRS/HIPEC): A Scoping Review.

Background/Objectives: Cytoreductive surgery combined with hyperthermic intraperitoneal chemotherapy (CRS/HIPEC) is a complex, high-risk procedure associated with profound haemodynamic and metabolic perturbations. Perioperative fluid management and the risk of acute kidney injury (AKI) represent two of the most clinically significant and mechanistically interrelated anaesthetic challenges in this setting. This scoping review aimed to synthesise the current evidence on perioperative fluid therapy strategies and renal protection in CRS/HIPEC, examining the pathophysiological rationale, comparative outcomes of different fluid therapy strategies, haemodynamic monitoring modalities, AKI incidence and risk factors, and pharmacological nephroprotective strategies. Methods: The review followed PRISMA guidelines and was registered in the Open Science Framework (osf.io/864pr). Studies specifically addressing fluid management, haemodynamic monitoring, AKI, and nephroprotection in adult patients undergoing CRS/HIPEC were included. Results: Thirty-one studies met inclusion criteria across two thematic domains: 13 addressing fluid therapy (two RCTs, one systematic review, and 10 observational studies) and 18 addressing AKI and renal protection (two RCTs, one systematic review, and 15 observational studies). Liberal intraoperative fluid administration is independently associated with increased morbidity and prolonged hospital stay. Restrictive and goal-directed strategies appear safe and are associated with improved outcomes. AKI incidence ranges from 7.9% to 45.5% depending on chemotherapy regimen, with platin- and taxane-based HIPEC conferring the highest risk. Sodium thiosulfate, amifostine, and cilastatin demonstrate nephroprotective effects in retrospective cohorts; dexmedetomidine shows subclinical renal biomarker benefits in the only RCT identified. Conclusions: The available evidence supports restrictive and goal-directed fluid strategies guided by dynamic haemodynamic monitoring, alongside individualised, cisplatin-dose-adapted nephroprotective protocols. Both fluid overload and renal hypoperfusion represent modifiable risk factors for AKI in CRS/HIPEC. Prospective randomised trials integrating fluid management and renal outcome endpoints are required.