Effect of dexmedetomidine on postoperative cognitive dysfunction in patients after cardiac surgery with cardiopulmonary bypass

Abstract

Objective To evaluate the effect of dexmedetomidine (DEX) on inflammatory responses in patients performed cardiac surgery with cardiopulmonary bypass (CPB) at perioperative period, and explore the influencing factors of postoperative cognitive dysfunction (POCD) in these patients. Methods Eighty patients scheduled for cardiac surgery with CPB at hospital from July 2013 to June 2014 were randomized into control group and DEX group (n=40). Before induction of anesthesia, DEX was administered to the patients from DEX group with a loading dose of 1 μg/kg followed by maintenance dose of 0.5 μg/(kg·h), while the same dose of normal saline was administered to patients from control group. Before incision (T0), 30 min after beginning of CBP (T1), 30 min after end of CBP (T2), end of surgery (T3), 24 h after end of surgery (T4) and 72 h after end of surgery (T5), venous blood samples from jugular bulb catheters were drawn, and serum concentrations of tumor necrosis factor α (TNF-α), interleukin (IL)-6 and IL-10 were determined. One d before operation, 3rd, 7th, 90th and 180th day after operation, the cognitive functions of patients were tested with mini-mental state examination (MMSE), digit span subtest (DSpan), digit symbol subtest (DSy) and trail making test (TMT). The DSpan contained digit span forward subtest (DSpan-F) and digit span reverse subtest (DSpan-R). Results The serum concentrations of TNF-α, IL-6 and IL-10 in two groups at T1, T2 and T3 were significantly higher than those at T0 (P<0.05); the serum concentrations of TNF-α and IL-6 in DEX group were significantly lower than those in control group (P<0.05), while that of IL-10 in DEX group was significantly higher than that in control group (P<0.05). In the control group, all results excepted for TMT on the 3rd d after operation, MMSE and DSpan-R results on the 7th d after operation, and DSpan-R results on the 90th d after operation were significantly lower than those results one d before operation (P<0.05); in the DEX group, MMSE and DSpan-R results on the 3rd d after operation were significantly lower than those results one d before operation (P<0.05); MMSE and DSpan-R results on the 3rd and 7th d after operation, and DSpan-R results on the 90th d after operation in the DEX group were significantly higher than those in the control group (P<0.05); TMT on the 3rd d after operation in the DEX group was significantly lower than that in the control group (P<0.05). The incidence rate of POCD in the DEX group on the 3rd and 7th d after operation (23.5% and 14.7%) was significantly lower than that in the control group (46.9% and 37.5%, P<0.05). Conclusion DEX with a loading dose of 1 μg/kg followed by maintenance dose of 0.5 μg/(kg·h) can reduce the early incidence of POCD in cardiac surgery with cardiopulmonary bypass, but can not reduce the late incidence. Key words: Dexmedetomidine; Cardiopulmonary bypass; Cardiac surgery; Neuroinflammation; Postoperative cognitive dysfunction