Comparison of the effects of normal saline versus Plasma-Lyte® on acid–base balance during living donor kidney transplantation surgery using goal-directed fluid therapy based on pulse pressure variation- a randomised controlled trial

Normal saline (NS) is commonly used during kidney transplantation but may cause hyperchloremic metabolic acidosis when administered in large volumes. Balanced crystalloids such as Plasma-Lyte® (PL) may attenuate these effects. We compared acid–base outcomes of NS versus PL when administered using pulse pressure variation (PPV)- guided goal-directed fluid therapy during living donor kidney transplantation (LDKT). In this prospective randomised assessor-blinded trial, adult patients undergoing LDKT were allocated to receive intraoperative NS or PL. Fluid administration was titrated according to a predefined PPV-guided algorithm. Acid–base status was assessed using the Stewart physicochemical analysis. The primary endpoint was the difference in apparent strong ion difference (SIDa). Secondary outcome measurements included haemodynamics, electrolytes, lactate, serum creatinine trends, dialysis requirement, and graft function. A total of 111 patients were analysed (NS, n = 55, PL, n = 56). Baseline characteristics and total intraoperative fluid volumes were comparable (1796 ± 337 vs 1903 ± 434 mL; p = 0.15). Apparent strong ion difference declined over time in both groups (time effect p < 0.001), but did not differ between groups (group effect p = 0.50; interaction p = 0.37). In the baseline-adjusted analysis (ANCOVA) of the primary endpoint, the adjusted between-group difference in SIDa at the end of surgery was 0.71 mmol/L (90% CI − 0.90 to + 2.32 mmol/L) against the pre-specified equivalence margin of ± 2 mmol/L; formal equivalence was not established, although no significant difference was detected (adjusted p = 0.46). Effective strong ion difference (SID e) , strong ion gap (SIG), pH, serum potassium, and lactate were similar at all measured time points ( p > 0.05). Early graft dysfunction (4.1% vs 7.4%; p = 0.472) and delayed graft function (3.6% vs 0%; p = 0.150) did not differ significantly; however, the trial was not powered for these exploratory outcomes. Postoperative creatinine trajectories did not differ between groups. During LDKT, PPV-guided goal-directed fluid therapy produced no significant between-group difference in acid–base balance or early graft outcomes with NS and PL. Formal equivalence in the primary endpoint was not established; nonetheless, at the moderate volumes delivered, the findings suggest that haemodynamic strategy may influence perioperative acid–base status more than crystalloid choice. The study was prospectively registered in the Clinical Trials Registry of India (ctri.nic.in) Registration number: CTRI/2021/01/030227 Registered on 04/01/2021.