Minimum Effective Volume of Local Anesthetic for Shoulder Analgesia by Ultrasound-Guided Block at Root C7 With Assessment of Pulmonary Function

The minimum effective volume of local anesthetic for shoulder analgesia for a US-guided block at the C7 root level in 50% and 95% of the patients was 2.9 and 3.6 mL, respectively. Pulmonary function was unchanged until 2 hrs after completion surgery, but reduced 22 hrs after start of a continuous infusion of ropivacaine 0.2%.