Randomized Clinical Trial of Ringer's Lactate Versus Chloride-Reduced Saline-Dextrose in Postoperative Kidney...

Normal saline administration induces hyperchloremic metabolic acidosis, potentially impairing kidney allograft recovery. The comparative efficacy of balanced crystalloids against actively chloride-reduced saline protocols remains unclear.

This randomized, open-label trial compared Ringer's Lactate Solution (RLS) with a dynamic dual-infusion protocol of normal saline and 5% dextrose (NSS + D5W) in adult kidney transplant recipients. Using a prespecified modified intention-to-treat analysis, 134 patients who received ≥2 L of study fluid were evaluated. Fluids were strictly titrated to hourly urine output. The primary outcome was day-4 serum bicarbonate. Secondary outcomes evaluated the overall treatment strategy, including protocolized rescue bicarbonate requirements, 1-month estimated glomerular filtration rate (eGFR) as an indicator of early functional recovery, and exploratory mechanistic biomarkers (urine neutrophil gelatinase-associated lipocalin [NGAL] and serum cytokines).

On postoperative day 4, the RLS group maintained significantly higher serum bicarbonate (19.39 vs. 17.31 mEq/L; P < 0.001) and required substantially less rescue bicarbonate therapy (17.9% vs. 58.2%; P < 0.001) compared with the NSS + D5W group. Serum chlorides were comparable between groups on day 4. RLS was associated with more favorable early allograft function, evidenced by a higher 1-month eGFR (61.63 vs. 53.18 ml/min per 1.73 m²; P = 0.028). Among the deceased-donor recipients, a lower proportion of RLS group had high urine NGAL (>100 ng/ml) and elevated interferon-γ; however, the continuous NGAL comparison was not significant and other cytokines (tumor necrosis factor [TNF]-α, interleukin [IL]-6, and IL-10) did not differ. These exploratory biomarker findings are hypothesis-generating.

RLS effectively reduces early postoperative metabolic acidosis and was associated with better short-term allograft functional recovery compared with a chloride-reduced saline regimen. These benefits are most applicable to allografts exhibiting immediate or early function that permits standard volume expansion.