Abstract Title: Supraclavicular vs. Interscalene Brachial Plexus Block for Shoulder Surgery

Authors: Christopher A. DiMeo, MD, New York, NY
Andrew Cameron, MB ChB, New York , NY; Christopher Cook, DO, New York , NY; Victor Zayas, MD, New York , NY; Dorothy Marcello, BA, New York , NY

ABSTRACT BODY

Background
Despite its well documented constellation of side effects (hemidiaphragmatic paresis, Horner’s syndrome and hoarsenes), interscalene block (ISB) is considered the regional anesthetic of choice for surgery of the shoulder. This study compared the efficacy and side effect profile of an alternative technique, ultrasound guided supraclavicular block (SCB), with ultrasound guided interscalene block (ISB) for ambulatory arthroscopic shoulder procedures, focusing on comparative efficacy and side effect profiles.

Methods
In this double blinded, randomized controlled trial, patients were randomized to receive either ultrasound guided SCB or ultrasound guided ISB for outpatient arthroscopic shoulder surgery. Prior to block placement, patients underwent ultrasound imaging of the hemidiaphragm on the surgical side, digital photography of the pupils and digital voice recordings. After block placement, the aforementioned tests were repeated for later comparison by a blinded third party. In addition, intraoperative block efficacy was recorded.

Results
Both ultrasound guided SCB and ISB provided complete anesthesia 100% of the time without the need for supplementation or conversion to general anesthesia. Mean time to perform ultrasound guided ISB was 5.35 minutes, versus 4.95 minutes for ultrasound guided SCB. The difference in mean time to perform either block was not statistically significant. 21.9% of patients randomized to receive ultrasound guided SCB developed partial or complete Horner’s syndrome (miosis and/or ptosis), versus 32% of patients randomized to receive ultrasound guided ISB. Ultrasound images of hemidiaphragmatic movement revealed paradoxical hemidiaphragmatic movement in 76% of ISB patients versus 40.6% of SCB patients. Finally, 56% of ISB patients demonstrated hoarseness, versus 46.7% of SCB patients.

Discussion
Ultrasound guided supraclavicular block is an equally efficacious anesthetic technique for arthroscopic shoulder surgery when compared to ultrasound guided interscalene block. Furthermore, ultrasound guided SCB is associated with a reduction in the rate of hemidiaphragmatic paresis. It is also worth noting that because ultrasound guided SCB is performed in a more caudad position along the course of the brachial plexus, it eliminates the possibility of neuraxial and/or phrenic nerve complications (such as spinal/epidural/subdural anesthesia and persistent phrenic nerve paresis) that have been described in association with interscalene block. Therefore, in light of its equivalent efficacy, reduced side effect profile (hemidiaphragmatic paresis) and diminished potential for catastrophic complications, the authors of this study believe that ultrasound guided SCB should be considered the anesthetic technique of choice for surgery of the shoulder.

ATTACHED FILES

Reg Anesth Pain Med 2010; 12