Locating Adductor Canal and Quantifying the Median Effective Volume of Ropivacaine for Adductor Canal Block by Ultrasound.

Abstract

To identify the precise position of adductor canal; and to determine median effective volume (EV50) for adductor canal block (ACB) by ultrasound. Observational study. Department of Anesthesiology, the First Central Hospital of Baoding, China from January 2019 to December 2020. One hundred and ninety subjects were recruited for mapping, the precise location of adductor canal. Twenty-four patients were scheduled to study the EV50 of ropivacaine. Ultrasound was used to identify the anatomical structure of femoral triangle as well as the cephalad and caudad end of adductor canal. By using the up-and-down method to study the effect of nerve block, the EV50 of 0.5% ropivacaine on ACB was quantified. The femoral triangle, the cephalad, and caudad end of adductor canal were clearly shown in the ultrasound images of all subjects. The midpoint between anterior superior iliac spine and the superior margin of patella is in femoral triangle. The cephalad edge of adductor canal is distal to the midpoint between anterior superior iliac spine and the superior margin of patella. The midpoint between the femoral trochanter and the superior margin of patella is in the adductor canal. EV50 of 0.5% Ropivacaine for ACB is 10.79 ml (95% CI, 10.10-11.52 ml). The midpoint between the femoral trochanter and the superior margin of patella is in the adductor canal. EV50 of 0.5% ropivacaine for ACB is 10.79 ml (95% CI, 10.10-11.52 ml). Key Words: Adductor canal, Location, Ultrasound, Median effective volume, Nerve block.