Background: Surgical stress induces stress hormone release and sympathetic hyperactivation, resulting in hemodynamic instability. Dexmedetomidine has sympatholytic and hemodynamic stabilizing effects. We investigated whether dexmedetomidine could attenuate stress responses in major spine surgery.
Methods: In this prospective randomized study, 52 patients undergoing spine fusion surgery were randomized to placebo (N.=26) or to dexmedetomidine (N.=26) groups. Dexmedetomidine at a rate of 0.4 μg/kg/h or saline was infused, starting immediately after anesthetic induction and continuing until the end of surgery. Anesthesia was performed using desflurane and remifentanil in both groups. Serum levels of cortisol, epinephrine, norepinephrine, and interleukin-6 were assessed before surgery (T1), at the surgical incision (T2), at the bone procedure (T3), and one hour after surgery (T4). The hemodynamic variables and the autonomic nervous system balance evaluated with heart rate variability were assessed at the same time points.
Results: Epinephrine and norepinephrine levels were higher over time in the control rather than in the dexmedetomidine group (P=0.001 and <0.001, respectively). The changes in cortisol, interleukin-6, and hemodynamics were similar between the groups. In the heart rate variability analysis, high-frequency decreased and low-frequency and low-frequency/high-frequency ratio increased during surgery in the control group, whereas they were maintained at the baseline level in the dexmedetomidine group. The changes in high-frequency, low-frequency, and the low-frequency/high-frequency ratio over time differed between the groups (P=0.009, 0.024, and 0.011, respectively).
Conclusions: Intraoperative dexmedetomidine administration reduced stress hormone release and maintained the balance of the autonomic nervous system. Dexmedetomidine could attenuate surgical stress response without untoward hemodynamic adverse events.