Changes in Pulse Wave Transit Time and Its Variability After Placement of Interscalene Brachial Plexus Block

Using a linear ultrasound transducer connected to an ultrasound machine, the compactly arranged brachial plexus is visualized lateral to the pulsating subclavian artery. The transducer is moved cephalad to visualize the 5th to 8th cervical (C5 to C8) nerve roots located between the anterior and middle scalene muscles. Using an in-plane technique, a block needle is inserted close to a nerve root in a lateral-to-medial direction. The needle is moved to place 0.75% ropivacaine around each nerve root. The C8 nerve root is blocked first, and the C5 nerve root is blocked last. After blocking the four cervical nerve roots, ropivacaine is placed in the intermuscular plane between the sternocleidomastoid and scalene muscles to block the supraclavicular nerves. A total of 26 ml of 0.75% ropivacaine is used for the interscalene brachial plexus block (6 ml per nerve root and 2 ml for the supraclavicular nerves).