Stroke Volume Variation Directed Versus Conventional Fluid Therapy for Postoperative Acute Kidney Injury after Percutaneous Nephrolithotomy - A Randomized Pilot Study

Background: Percutaneous nephrolithotomy (PCNL) surgery may be associated with postoperative Acute Kidney Injury (AKI). Commonest intraoperative risk factors for postoperative AKI include hypotension and hypoperfusion. Intravenous fluids are administered during surgery to optimize intravascular status and thus prevent hypotension. Conventionally, intravenous fluids are administered during surgery using pre-calculated volumes based on maintenance needs. Alternatively, goal-directed fluid therapy using Stroke Volume Variation (SVV) can be used to decide the volume of intravenous fluids. We compared early postoperative AKI following intraoperative use of conventional (group C, n=15) versus SVV directed fluid therapy (group S, n = 17) in patients undergoing PCNL surgery. Methods: This double-blinded pilot study involved 32 adult patients, randomised to two groups according to type of intraoperative fluid therapy (group C or group S). Postoperative AKI was diagnosed as per KDIGO guidelines. Results: Incidence of early postoperative AKI was clinically higher for group S, though statistically similar, as compared to group C (47.1% versus 26.7%) (P = 0.234). Postoperative increase in eGFR, and 24-hour urine output were clinically greater for group S (P > 0.05). Volume of intraoperative fluids infused was significantly lesser for group S (P = 0.000). The incidence of hypotension and requirement of vasopressor to maintain blood pressure was clinically lesser, though statistically similar for group S as compared to group C (P = 0.659). Conclusions: There appears to be a clinical trend of greater incidence of AKI with use of SVV guided therapy despite better intraoperative hemodynamic stability and greater improvement in postoperative urine output and eGFR in the first postoperative day. Keywords: Percutaneous nephrolithotomy, Acute kidney injury, Fluid therapy, General anesthesia, Blood pressure