| Objective:To observe the effects of dexmedetomidine combined with the right upper limb ischemic preconditioning on automatic cardiac rebeating rates after aorta declamping and serum c Tn T,IL-6,TNF-?,MDA,SOD concentrations during and after valve replacement surgery in adult patients. To explore myocardial protective effect and mechanism of dexmedetomidine combined with remote ischemic preconditioning. Methods:Eighty patients were enrolled and randomly divided into four groups: controlled group(group C, n=20),dexmedetomidine group(group D, n=20),right upper limb ischemic preconditioning group(group R,n=20) and dexmedetomidine combined with the right upper limb ischemic preconditioning group(group DR,n=20).In group D, a dose of dexmedetomidine 0.4ug/kg was injected intravenously 30 min before aorta clamping. In group R, when dexmedetomidine was being injected, tourniquet fasten to the right upper extremity was inflated(6cm wide,the lower edge 2-3cm away from elbow joint,pressure maintained at 200 mm Hg),lasted for 5 minutes,then deflated for 5 minutes.The above process repeated 3 times(30 minutes in total).Group DR combined the above two kinds of processing methods. In group C,there was no any treatment processed.All patients were premedicated with penehyclidine 0.01-0.02mg/kg,and induced with sedative?analgesia?muscle relaxants followed by intratracheal intubation and ventilation. The surgery was maintained under total intravenous anesthesia. During the surgery, MAP was maintained in the range of 50-80 mm Hg, and ECG?Sp O2?IBP?BIS?CVP?T?PETCO2?urine volume were continuously monitored. CPB time,aorta blocking time,automatic cardiac rebeating rate, operation time, ventilation time, extubation time, postoperative ICU stay time, cumulative postoerative time and dosage of vasoactive drugs, hospitalization time were recorded. Besides, the venous blood samples were collected for the detection of serum concentrations of c Tn T,IL-6,TNF-?,MDA,SOD after anesthesia induction(T0), at 2h after aorta declamping(T1), at 12 h after aorta declamping(T2), at 24 h after aorta declamping(T3), at 48 h after aorta declamping(T4) respectively. Results: 1.There were no remarkable differences in age, gender, weight, body mass index, preoperative EF, and surgical types in four groups(P>0.05).2.The differences of CPB time, aorta blocking time, automatic cardiac rebeating rate, operation time, ventilation time, extubation time, postoperative ICU stay time, hospitalization time were not statistically significant in all groups(P>0.05).3.There were no differences in HR?MAP in all groups at T0?T1?T2?T3?T4(P>0.05).Compared with group C,the time and dosage of dopamine and dobutamine were significantly lower in group D?R?DR(P<0.05). Compared with group D or group R, the time and dosage of dopamine and dobutamine were lower in group DR(P<0.05). No differences were found in the time and dosage of dopamine and dobutamine between group D and group R(P>0.05).4.Troponin-T(c Tn T):(1)Intra-group comparison :Compared with T0, the serum concentration of c Tn T increased markedly in all groups at T1?T2?T3?T4(P<0.05);(2)Comparison in all groups:Compared with group C,the serum concentration of c Tn T at T1?T2?T3?T4 was significantly lower in group D?R?DR(P<0.05); Compared with group D or group R,the serum concentration of c Tn T at T3?T4 was lower in group DR(P<0.05); No differences were existed between group D and group R(P>0.05).5. Interleukin-6(IL-6):(1)Intra-group comparison:Compared with T0, the serum concentration of IL-6 increased markedly in all groups at T1?T2?T3?T4(P<0.05);(2)Comparison in all groups:Compared with group C,the serum concentration of IL-6 at T1?T2?T3?T4 was significantly lower in group D?R?DR(P<0.05); Compared with group D or group R,the serum concentration of IL-6 at T3 was lower in group DR(P<0.05); No differences were existed between group D and group R(P>0.05).6.Tumor Necrosis Factor-alpha(TNF-?):(1)Intra-group comparison:Compared with T0, the serum concentration of TNF-? increased markedly in all groups at T1?T2?T3?T4(P<0.05);(2)Comparison in all groups:Compared with group C,the serum concentration of TNF-? at T1?T2?T3?T4 was significantly lower in group D?R?DR(P<0.05); No differences were existed at T1?T2?T3?T4 among group D?R?DR(P>0.05).7.Malondialdehyde(MDA):(1)Intra-group comparison:Compared with T0, the serum concentration of MDA increased markedly in all groups at T1?T2?T3?T4(P<0.05);(2)Comparison in all groups:Compared with group C,the serum concentration of MDA at T1?T2?T3?T4 was significantly lower in group D?R?DR(P <0.05); No differences were existed at T1?T2?T3 ? T4 among group D ? R and DR(P>0.05).8.Super Oxidase Dimutase(SOD):(1)Intra-group comparison: Compared with T0, the serum concentration of SOD increased markedly in all groups at T1?T2?T3?T4(P<0.05);(2)Comparison in all groups: Compared with group C,the serum concentration of SOD at T2?T3?T4 was higher in group D?R?DR(P<0.05); No differences were existed at T1?T2?T3?T4 among group D?R and DR(P>0.05).Conclusion:1.In cardiac valve replacement surgery, dexmedetomidine preconditioning ? the right upper limb ischemic preconditioning and dexmedetomidine combined with the right upper limb ischemic preconditioning are effective in myocardial protection, which may be related to the inhibition of systemic inflammatory response syndrome and oxidative stress.2.The myocardial protection effect of dexmedetomidine combined with the right upper limb ischemic preconditioning is superior to dexmedetomidine or single limb ischemic preconditioning, which may be related to further inhibit the systemic inflammatory response syndrome. |
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