Ultrasound-guided ISB
lower trunk [
SKIN, STERILE, LOCAL INFILTRATION
Patients were placed in the supine position with the shoulders and arms naturally placed on both sides of the body and the head tilted to the opposite side from the surgical site. Then they were sedated with midazolam (0 to 20 mcg/kg) to achieve a Richmond Agitation-Sedation Scale score of − 2 to − 3. Skin disinfection was performed using betadine (Mingyaotang Pharmaceutical Technology Development Co., Ltd, Qingdao, China) and sterile drapes were applied according to the sterile principles guidelines. All blocks were completed by the same experienced anesthesiologist. A 5–12 MHZ high-frequency linear array probe was applied with ultrasonic coupling agent and then covered with a sterile membrane. After local infiltration anesthesia using 1% lidocaine 5 ml, a 22 G insulated puncture needle with 0.375% ropivacaine was applied. The ultrasound probe in group I was placed on the side of the neck to obtain a transverse view of the brachial plexus between the anterior scalene muscle and the middle scalene muscle. Cross-sectional imaging of the peripheral blood vessels and the position of the scalene muscle were used to determine the position of the brachial plexus trunk in the interscalene, which manifested as multiple circular or elliptical hypoechoic areas between the anterior scalene muscle and the middle scalene muscle, surrounded by a hyperechoic halo. The needle was inserted using an in-plane insertion technique, until the needle tip reached around upper trunk, middle trunk, and lower trunk [