[Effects of dexmedetomidine preconditioning attenuating remote lung injury of lower limb ischemia-reperfusion]

To investigate the effects of dexmedetomidine preconditioning attenuating remote lung injury of lower limb ischemia-reperfusion.

Sixty patients form Central Hospital of Cangzhou scheduled for lower limb operation with tourniquet from January 2014 to June 2014. Lumbar plexus combined with sciatic nerve block was performed guided by a nerve stimulator in both groups. All patients were randomly assigned to two groups, conventional general anesthesia group (R group, n = 30) and dexmedetomidine preconditioning group (Pre-Dex group, n = 30). In the group Pre-Dex, a dexmedetomidine intravenous infusion was started at a dose of 0.125 ml/kg (4 µg/ml) for 10 minutes before using tourniquet, whereas group R received an equivalent volume of normal saline. Blood samples were taken in femoral vein for 4 ml. Monocytes TLR4 expression and interleukin-6(IL-6), interleukin-8(IL-8), tumor necrosis factor-α(TNF-α) level were determinated 15 minute before tourniquet inflation(T(1)), 15 minute (T(2)), 2 h(T(3)), 6 h(T(4))and 24 h(T(5)) after tourniquet release. Artery blood gas analysis, respiratory index and oxygenation index were measured by drawing off femoral artery for 2 ml.

Compare with T(1), RI in group R was higher at T(4) and OI was lower at T(3-5) (P < 0.01), and there were no significant differences in group Pre-Dex at T(2)-T(5) about RI and OI (P > 0.05); IL-8,IL-6 level at T(3)-T(5) and TNF-α level at T(2)-T(5) in group R were significantly higher. IL-8,IL-6 level at T(3)-T(4) and TNF-α level at T(2)-T(4) in group Pre-Dex were higher. Monocytes TLR4 expression was higher in group R at T(3)-T(4) (P < 0.05). Compare with group R, RI in group Pre-Dex was lower and OI was higher at T(4) (P < 0.05); IL-8, IL-6 level at T(3)-T(5) and TNF-α level at T(2)-T(4) in group Pre-Dex was significantly lower (P < 0.05). Monocytes TLR4 expression was lower in group Pre-Dex at T(3)-T(5) (P < 0.05). IL-6, IL-8 level had positive correlation with TLR4 and RI ((r = 0.673, 0.647, 0.521, 0.457, P < 0.01 ), but had negative correlation with OI in group R (r = -0.613, -0.578, P < 0.01).

Dexmedetomidine preconditioning attenuate remote lung injury of lower limb ischemia-reperfusion, and the mechanism may be related to down-regulation of monocytes TLR4 expression and degradation of IL-6, IL-8 and TNF-α level.