Deep anesthesia worsens outcome of rats with inflammatory responses

Objective: We tested the hypothesis that deep anesthesia with sevoflurane, known as a potent immunomodulator, for 4 h would worsen the 24-h outcomes of rats through modulation of the inflammatory responses. Methods: Forty-nine male Wistar rats, administered low dose of lipopolysaccharide (0.5 mg/kg) intravenously to elicit moderate inflammatory responses mimicked mild surgical stress, underwent one minimum alveolar concentration (MAC) or 2 MAC sevoflurane anesthesia for 4 h. The 24-h survival rate, arterial blood gases, plasma interleukin (IL)-6 and tumor necrosis factor (TNF)-α concentrations, and rate of T lymphocyte apoptosis in spleen were evaluated. We further examined the effects of hypotension and TNF-α discharge on the survival rate. Results: The survival rate in 2 MAC group was significantly lower accompanied with decreased base excess and increased level of cytokines (IL-6, TNF-α) compared to 1 MAC group. The apoptosis rate did not differ between the two groups. Neither norepinephrine infusion to restore hypotension nor administration of anti-TNF-α antibody improved the outcome in the 2 MAC group. Conclusions: Deep anesthesia with sevoflurane even for a short-term period augments the release of inflammatory cytokines evoked by inflammatory insults like surgical stress, impairs the acid–base balance, and subsequently deteriorates the outcomes.