Comparison of the Analgesic Duration of 0.5% Bupivacaine With 1:200,000 Epinephrine Versus 0.5% Ropivicaine Versus 1 % Ropivicaine for Low Volume Ultrasound-guided Interscalene Brachial Plexus Block

Severe pain following shoulder surgery is common and remains a major challenge. The interscalene nerve block is well suited for operations on the shoulder or upper arm, for providing surgical anesthesia as well as prolonged effective postoperative analgesia.

Modern ultrasound guided ISB (US-ISB) allows for more accurate, targeted deposition of local anesthetic. The current trend is to lower the volume of local anesthetic for ultrasound-guided interscalene block in order to reduce potential complications such as phrenic nerve paralysis and local anesthetic toxicity. However, at low volumes the analgesic duration of the block could be compromised. Studies to elucidate the best local anesthetic agent, concentration and adjuncts to prolong analgesia at low volumes are needed. Ropivacaine and Bupivacaine are long acting local anesthetics commonly used for peripheral nerve blocks, however, there are no studies comparing their analgesic duration in the setting of low volume interscalene block to date.

This study will investigate the analgesic duration of 0.5% Ropivacaine versus 0.5% Bupivacaine with 1:200,000 epinephrine versus 1% Ropivacaine for low volume US-ISB.

This study aims to conduct a comparison of the duration of post operative analgesia achieved by these agents, hence allowing the appropriate local anesthetic agent and concentration selection in low-volume techniques.