[Effects of dexmedetomidine doses on postoperative cognitive dysfunction and serum β- amyloid and cytokine levels in elderly patients after spine surgery: a randomized controlled trial].

Objective: To explore the immunomodulatory mechanism and optimal dose of dexmedetomidine (DEX) for preventing postoperative cognitive dysfunction (POCD) in elderly patients undergoing spinal surgery.
Objective: A total of 120 elderly patients undergoing elective spinal surgery with general anesthesia were randomized into 4 groups to receive a loading dose of 0.3 μg/kg DEX for 10 min before anesthesia induction followed by maintenance doses of 0.2, 0.5, and 0.8 μg · kg ^-1 ·h ^-1 (low-, medium-, and high-dose DEX groups, respectively) or an equal volume of normal saline (control group). DEX and saline was discontinued 40 min before the end of the surgery. Before induction (D ₀ ) and on day 1 (D ₁ ), day 3 (D ₂ ) and day 7 (D ₃ ) after the operation, the cognitive function of the patients was assessed using the MMSE scale and their serum levels of β-amyloid (Aβ), TNF-α, IL-1β and IL-6 were measured. The occurrence of adverse effects including bradycardia and hypotension and the recovery time of the patients were recorded.
Objective: Compared with those on D ₀ , serum levels of Aβ, IL-1β, IL-6, and TNF-α on D ₁ were markedly increased in all the groups ( P < 0.05); the levels of Aβ decreased to the baseline level on D ₃ in medium- and high-dose DEX groups ( P > 0.05) but remained high in the other two groups. On D ₂ , TNF-α, L-1β and IL-6 recovered their baseline levels in medium- and high-dose DEX groups ( P > 0.05) but remained elevated in the other two groups. The incidences of POCD in medium- and high-dose DEX groups were comparable but significantly lower than that in the control group ( P < 0.05). The incidences of hypotension and bradycardia were the highest in high-dose DEX group ( P < 0.01), which also had longer recovery time than the other 3 groups ( P < 0.05).
Objective: With a loading dose of 0.3 μg/kg followed by a maintenance doses of 0.5 μg · kg ^-1 ·h ^-1 , DEX can effectively reduce the incidence of POCD in elderly patients undergoing spinal surgery by inhibiting the production of Aβ and pro-inflammatory cytokines.