Effects Of Ultrasound-Guided Sciatic Nerve Block On Arterial Velocity And Skin Temperature In The Distal Lower Extremity

OBJECTIVE: In this study,patients with ankle surgery were studied.Doppler ultrasound combined with far-infrared thermography was used to investigate the effects of ultrasound-guided sciatic nerve block on the peak systolic velocity of tibial arteries and the skin temperature at the distal extremity.METHODS: Thirty-three patients,aged 20 to 75 years old,American Society of Anesthesiologists(ASA)grade I or II,who underwent an ankle-surgery operation at the Ningbo No.2 Hospital from November 2018 to February 2019 were enrolled.All the patients received general anesthesia combined with peripheral nerve block anesthesia.All patients underwent ultrasound-guided popliteal approach for sciatic nerve block with injection of 0.3% ropivacaine 20 ml.Systolic peak velocity(PSV)of anterior tibial artery(AT)and posterior tibial artery(PT),and skin temperature of the dorsal region,the hallux region,and the anterior tibia region was recorded before sciatic nerve block(T0),15 min(T1),30 min(T2),and 45 min(T3)after sciatic nerve block.RESULTS: There were significant differences in PSV of the AT and PT among the time points(F=19.87,14.9,both P<0.001).Compared with T0,the PSV of the AT increased by 35.54% and 54.50%(t=6.164,7.926,both P<0.001),and the PSV of the PT increased by 25.63% and 48.24%(t = 4.62,6.623,both P < 0.01),respectively.There was a statistically significant difference in skin temperature between the hallux area and the dorsal area of the lower limbs(F=11.72,2.401,both P<0.001).Compared with T0,the skin temperature of the hallux region increased 1.2 ℃ and 3.4 ℃(t=2.782,5.946,P<0.05,0.001),and the skin temperature distribution in the dorsal area increased 1.3 ℃ and 2.9 ℃(t = 4.88,7.258,both P<0.001).Compared with T0,the skin temperature in the anterior tibia region decreased 1.2 ℃(t=5.454,P<0.01).CONCLUSION: Ultrasound-guided sciatic nerve block significantly increases the blood flow velocity of the anterior tibial artery and posterior tibial artery,accompanying by the increase of skin temperature of the distal extremity,which may be beneficial to the early healing of ankle surgery patients and improve the survival rate of flap transplantation.