Saturday, November 24, 2012

Ultrasound-Guided Interscalene Block Anesthesia for Shoulder Arthroscopy JBJS

Ultrasound-Guided Interscalene Block Anesthesia for Shoulder Arthroscopy JBJS

This paper reviews 1319 patients having outpatient arthroscopic surgery and ultrasound-guided interscalene blocks. In the introduction, the authors emphasize the importance of cost control and suggest that interscalene blocks facilitate outpatient procedures by providing muscle relaxation and lessening the need for high-dose opiates and paralytics. Furthermore they point to the postoperative analgesia, which may reduce the need for pain medication after surgery. They also point to the risks of neuropathy and other potential complications of interscalene blocks. They propose that ultrasound guidance may reduce the risk of brachial plexus block and improve its success rate.

In their study patients received both ultrasound-guided interscalene blocks and laryngeal mask airway general anesthesia –distinguishing it from studies in which brachial plexus blocks are used alone without supplementation.

It is important to note that the authors carefully excluded patients with diabetes, patients having manipulations, and patients having capsular releases from this cohort because they were felt to be at high risk for neurological complications. One might extrapolate that these authors would be similarly reluctant to use these blocks in patients having shoulder arthroplasty for the same reasons. Importantly, the authors also carefully excluded patients with any neurologic issues (cervical radiculopathy, multiple sclerosis etc.), infection, coagulopathy, and chronic obstructive pulmonary disease (because of the temporary phrenic nerve paralysis that often results from a plexus block). Only patients of American Society of Anesthesiologists grade 1 or 2 (ASA 1 or 2) were included. The blocks were performed with attending anesthesiologists with more than 50 ultrasound-guided interscalene blocks under their belt. Bottom line is that this study was conducted to optimize both the patients included and the experience of the anesthesiologists.

Patients were discharged 1.5 hours after the end of the arthroscopy and experienced 14 hours of pain relief. The authors carefully documented the complications, very few of which could be attributed to the plexus block. 38 adverse events were noted; three patients had permanent sequelae (an MI, transverse myelitis, and persistent plexopathy). All other cases plexopathy and neuropathy resolved within four months. All but 2.2% of the patients were satisfied to the point that they would choose this anesthetic approach again.

While the authors conclude “Our study strongly supports the use of interscalene block for operative anesthesia and postoperative analgesia in patients undergoing shoulder arthroscopy.”, enthusiasts would be well advised (1) to recognize that “The levels of training and experience of the anesthesiologist are directly proportional to success and safety of regional anesthesia” and (2) to carefully exclude, as these authors admonish, patients at increased risk for complications.

Bottom line: in the hands of highly experienced anesthesiologists, the combination of ultrasound guided plexus block and general anesthesia is a highly attractive option for healthy patients having outpatient arthroscopy. The caveat is that the high degree of success reported here cannot be used to support the application of this anesthetic approach to less healthy patients having more complex surgical procedures and cannot be generalized to less experienced anesthesiologists as we have previously demonstrated.

As explained in previous posts, we avoid the use of brachial plexus blocks in patients having shoulder arthroplasty; they surely do not meet the criteria listed for inclusion in the study discussed above.


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