Relationship Between the Duration of Intravenous Ketamine Anesthesia and Postoperative Oxidative Stress and Inflammatory Response in Rats.

Surgical trauma triggers oxidative and inflammatory responses that contribute to postoperative complications. Although the antioxidant and anti-inflammatory effects of ketamine have been reported, the impact of anesthesia duration on these mechanisms remains unclear. Forty-two male Wistar rats were randomized into healthy control (HG), ketamine only (KET; 60 mg/kg, i.p.), or laparotomy plus ketamine with 0-4 additional ketamine doses at 20 min intervals (KET + L, KET + L1-L4). At 24 h, levels of MDA, tGSH, SOD, CAT, IL-1β, IL-6, TNF-α, adrenaline and noradrenaline were measured in tail-vein blood. One-way ANOVA with Tukey's post hoc test was used. Laparotomy under single-dose ketamine increased MDA and pro-inflammatory cytokines and decreased tGSH, SOD, CAT, ADR, and NDR versus HG and KET (all p < 0.001). After laparotomy, repeated ketamine dosing produced graded decreases in MDA and cytokines and increases in tGSH, SOD, CAT, ADR, and NDR toward control levels; effects were most pronounced in KET + L4 (all p < 0.001). Ketamine alone did not differ significantly from HG. In rats, ketamine modulates postoperative biological stress in a duration-dependent manner; prolonging anesthesia reduces oxidative-inflammatory load and restores catecholaminergic tone. These findings strongly support revisiting dose-duration protocols and underscore the need for mechanistic and clinical studies.