Abstract: ［Abstract］ Objective〖HTSS〗〓To investigate the effect and mechanism of dexmedetomidine combined with remote ischemic preconditioning(RIPC) on the lung injury in patients undergoing thoracoscopic thoracic surgery.
〖HTH〗〖WTHZ〗Methods〖HTSS〗〓Eighty patients,scheduled for thoracoscopic thoracic operation were randomly divided into 4 groups(n=20 each group) using a random number table: RIPC group(group A), dexmedetomidine group(group B), RIPC combined with dexmedetomidine group(group C) and control group(group D) . At 0 min(T0), 30 min(T1), 1h(T2) and 2 h(T3) of onelung ventilation(OLV), blood samples were obtained for blood gas analysis . Oxygenation index(OI), respiratory index(RI) and intrapulmonary shunt fraction(QS/QT) were calculated and plasma concentrations of tumor necrosis faetorα(TNFα), interleukin6(IL6) and malondialdehyde(MDA) were detected.
〖HTH〗〖WTHZ〗Results〖HTSS〗〓The RI and QS/QT of the four groups were increased  at T1-T2 and then decreased at T3, and these at T3 all were  higher than at T0. But OI of the four groups  was decreased  at T1-T2 and then increased at T3, and OI at T3 was lower than at T0. The differences  among the four groups, time points,interaction of groups time points were statistically significant(P＜0.05). The levels of  TNFα, IL6 and MDA of the four groups were increased  at T1-T2 and then decreased at T3, and those at T3 all were far higher than at T0. The differences  among the four groups, time points,interaction of groups time points were statistically significant(P＜0.05).
〖HTH〗〖WTHZ〗Conclusion〖HTSS〗〓Dexmedetomidine combined with RIPC could attenuate the lung injury during onelung ventilation in patients undergoing thoracoscopic thoracic surgery, and the mechanisms were related with inhibiting inflammatory responses, reducing airway acidification and reducing pulmonary shunt synergistically.

Key words: carcinoma, nonsmallcell lung, ischemic preconditioning, dexanedetomidine