Intervention technique
LISB
INFILTRATION
Venous access was established after arrival in the operating room without any premedication before anesthesia. During the same time, the vital signs of the patients were monitored every three minutes using a non-invasive blood pressure parameter, pulse oximeter, and electrocardiogram. Patients were kept supine with their heads facing away from the block side. All blocks were performed by the senior anesthesiologist (Z.-H.C.), who had performed over 200 ultrasound-guided peripheral nerve blocks. After sterilizing the region with povidone-iodine, 2% lidocaine (1 mL) was injected for local site subcutaneous infiltration. An 11 MHz linear probe (HITACHI ALOKA ARIETTA, America) was also wrapped with a sterilized plastic cover. The probe was located at a caudal 2/3 distance from C6 to ﻿the clavicle in the LISB group (Fig. Location and an ultrasound image of LISB and MISB. Note: 