Effects And Mechanisms Of Different Doses Of Dexmedetomidine On Early Cognitive Dysfunction In Elderly Patients Undergoing Lung Cancer Surgery

Objective:To investigate the effect of different doses of dexmedetomidine(Dex) on early postoperative cognitive dysfunction in elderly patients undergoing lung cancer surgery and explore the possible mechanismMethods:Sixty ASAI-III elderly patients(over 60 years) were randomized equally into 4 groups including a control group without dexmedetomidine and 3 dexmedetomidine groups(groups D1, D2, and D3) with loading dexmedetomidine doses of 0.5 μg/kg and maintenance doses of 0.2, 0.4, and 0.6 g·kg-1·h-1, respectively. Dex was discontinued 30 min before the end of surgery. The time of operation, peri-operative bleeding,MAP,HR and Sp O2 were recorded. Mini-Mental State(MMSE) test was used to assess the cognitive function 1 day before and at 1 day, 3 days,7days after the operation. The incidences of postoperative cognitive dysfunction(POCD) were calculated. Blood samples were taken immediately in four time points for determining the levels of plasma TNF-a and IL-6: before anesthesia induction(T0), immediately into the chest(T1), immediately after operation(T2) and at 1 day after operation(T3).Results:1. There were no significant differences in the aspects of fundamental state(P>0.05).2. Compared with T0,the MAP(T1) and HR(T2,T3) were increased obviously in group C; The HR(T1,T2) in three dexmedetomidine groups(groups D1, D2, and D3) were significantly lower(P<0.05)and there were no defferences in the three groups at each point of time(P>0.05). Compared with group C, The HR(T1) in two groups(groups D2 and D3) were significantly decreased(P<0.05).3.The MMSE score in group C and group D1 at 1 day and 3 days after operation were lower(P<0.05). The incidence of postoperative cognitive dysfunction(POCD) was significantly lower in groups D2 and D3 than in group C and D1(P<0.05).4. The levels of plasma TNF-a and IL-6 at T2,T3 in all four groups were higher than at T0(P<0.05).The two parameters at T2,T3 in groups D1,D2 and D3 were lower than in group C(P<0.05). There were significant differences between group D2,D3 with group C(P<0.05).Conclusion:Dexmedetomidine with a loading dose of 0.5 μg/kg followed by maintenance doses of 0.4 and 0.6μg·kg-1·h-1 can reduce the incidence of POCD in elderly patients undergoing lung cancer surgery.Its mechanism may be associated with the anti-inflammatory effects of Dex.