Objective To investigate the effect of transcutaneous electrical acupoint stimulation(TEAS) on pulmonary function

superoxide dismutase(SOD)activity

and malondialdehyde(MDA)content in patients using tourniquet after lower extremity surgery.Methods A total of 40 patients who underwent lower extremity surgery were equally randomized into control group and TEAS group by using a random number table. All patients underwent lumbar epidural anesthesia combined with block anesthesia. The patients in the TEAS group were given TEAS at Zusanli(ST36)and Sanyinjiao(SP6)beginning from 30 min before surgery to the end of surgery

and those in the control group received TEAS at the same acupoints with minimum current intensity. Mean arterial pressure(MAP)and heart rate(HR)were recorded at each time point(T0:pre-surgery/TEAS

T1:5 min after anesthesia

T2:1 min before tourniquet-loosening

T3:1 min after tourniquet-loosening

T4:5 min after tourniquet-loosening

and T5:6 h after tourniquet-loosening). Blood samples(4 mL)was collected from the radial artery before TEAS and 6 h after loosening tourniquet for analyzing blood gas parameters as partial pressure of caron dioxide(PCO2)

arterial partial pressure of oxygen(PaO2)

alveolar partial pressure of oxygen(PAO2)

alveolar-arterial oxygen pressure difference(PA-aDO2)and respiratory index(RI)by using a blood gas analyzer

and plasma SOD activity and MDA content were assayed by using xanthine oxidase method and thiobarbituric acid colorimetry method

respectively.Results Intra-group comparison showed that compared with T0

a significant increase was found in PA-aDO2 and RI at T5 and a significant reduction in PaO2 and PaO2/PAO2(a/A)ratio in the control group(P<0. 05)

and the same changes in the TEAS group(P<0. 05)except a/A ratio. Comparison between two groups showed that at T5

both PaO2 and a/A levels were significantly higher in the TEAS group than in the control group(P<0. 05)

and both PA-aDO2 and RI levels were obviously lower in the TEAS group than in the control group(P<0. 05)

suggesting an improvement of the pulmonary function after TEAS. At T5

plasma SOD activity was significantly decreased and plasma MDA content was remarkably increased in the control group relevant to T0(P < 0. 05)

SOD activity was significantly higher in the TEAS group than in the control group(P<0. 05)

and MDA content was evidently lower in the TEAS group than in the control group(P<0. 05)

suggesting a reduction of oxidative stress response after TEAS.Conclusion TEAS at ST36 and SP6 can improve pulmonary function and attenuate oxidative stress response in patients using tourniquet after lower extremity surgery.