Abstract: Objective To investigate the effect of butorphanol combined with flurbiprofen axetil in preventing tourniquet-induced ischemia-reperfusion injury (IRI)of the limbs. 
Methods A total of 120 patients undergoing unilateral artificial knee athroplasty inthe Second Hospital of Zhangjiakou City, Hebei Province, were randomly divided into four groups: control group, butorphanol group, flurbiprofen axetil group and the combination group, with 30 patients in each group. Heart rate (HR) and mean arterial pressure (MAP）, arterial oxygen saturation (SpO2), malondialdehyde (MDA), superoxide dismutase (SOD), tumor necrosis factor-α (TNF-α), interleukin-8 (IL-8), interleukin-6 (IL-6), increase rate of gastrocnemius muscle circumference of affected limb, knee joint circumference and quadriceps muscle circumference at 5 min before anesthesia (T0), at 5 min before tightening the tourniquet (T1), at 5 min before tourniquet loosening (T2), and at 30 min after tourniquet loosening (T3), and visual analogue scale (VAS) score before operation, and at 12 h, 24 h, and 72 h after operation were compared between two group. 
Results The difference of interaction between groups, time points and time points between groups was statistically significant with respect to HR, MAP and SpO2(P>0.05). In the control group, butorphanol group and flurbiprofen axetil group, MDA at T1, T2 and T3 was higher than that at T0, while SOD was lower than that at T0 (P＜0.05). MDA at T1, T2, and T3 in the combination group were lower than those in the butorphanol group, flurbiprofen axetil group and control group, and the SOD was higher than that in the butorphanol group, flurbiprofen axetil group and control group (P＜0.05). TNF-α, IL-8, IL-6 at T1, T2, and T3 in the control group, butorphanol group, and flurbiprofen axetil group were higher than those at T0 (P＜0.05). TNF-α, IL-8 and IL-6 at T1, T2, and T3 in the combination group were lower than those in the butorphanol group, flurbiprofen axetil group and control group (P＜0.05). The increase rate of gastrocnemius muscle circumference of the affected limb, knee joint circumference and quadriceps muscle circumference in the combination group were lower than those of but orphanol group, flurbiprofen axetil group and control group (P＜0.05). The pain VAS score at 12 h, 24 h, and 72 h in the combination group was lower than that in the butorphanol group, flurbiprofen axetil group and control group (P＜0.05). 
Conclusion Butorphanol combined with flurbiprofen axetil can reduce the inflammatory response and oxidative stress caused by tourniquet induced IRI, prevent limb IRI, relieve the swelling degree of the calf, and reduce the pain of patients, which is conducive to postoperative recovery. 

Key words: reperfusion injury, butorphanol, flurbiprofen axetil