Intervention
MCSL
In order to minimize the bias, all IJVC processes were completed by the same attending doctor who had completed ultrasound-guided IJVC for more than 500 cases. All IJVC procedures were performed under local anesthesia and using the Seldinger method, with a 6.35cm, 18-gauge needle (BIOSENSORS INTERNATIONAL™) attached by a 5 ml syringe. In the supine position, patients tilted their head to the leftward 30°, with a thin pillow under their shoulders to extend the neck. All patients underwent vital sign monitoring during the IJVC procedure. The same ultrasound equipment (UMT-500; Mindray, Shenzhen, China) with a high-frequency linear (8 - 13Hz) transducer of footprint size 47 mm was used for ultrasound guidance.In the MCSL group, IJVC procedures were conducted as described in our previous report [