Anesthesia Toolbox Question:

A 62-year-old woman with obesity, hypertension and chronic obstructive pulmonary disease presents for open reduction and internal fixation of a right distal radius fracture. The surgeon is planning an upper arm tourniquet during the procedure. Which of the following regional nerve blocks is the best choice for complete surgical anesthesia?

A. Interscalene  X

B. Supraclavicular  ✔

C. Cervical plexus block  X

Read the discussion and key information below.

Discussion:

The brachial plexus can be blocked at different levels to achieve the desired analgesic effect. Of the answers, only the supraclavicular will block the wrist. Choices for wrist surgery include: supraclavicular, infraclavicular, or axillary. All three approaches will also need an intercostobrachial nerve block as well for tourniquet pain (branches off of the T2 root and missed will all brachial plexus blocks). If the patient is very obese, an axillary block can be easier as it’s more superficial and often easy to see under ultrasound, however, you do need to block each branch (including the musculocutaneous nerve). The axillary block is a brachial plexus block performed at the level of nerve branches. If you’re very worried about her COPD, avoidance of supraclavicular approach (trunk/division level block) is wise as local anesthetic can also block the phrenic nerve leading to respiratory compromise from hemidiaphragm. The infraclavicular block is a cord level block and can be difficult to see on ultrasound in patient with obesity and carries a higher risk of pneumothorax that the supraclavicular (which carries some risk) or axillary (which carries almost no risk for pneumothorax). The interscalene block (root level block) will often miss nerve roots C8 and T1 which contribute to ulnar nerve, making it a poor choice. Although this is not the primary sensory area, the ulnar nerve innervates thumb abduction and this needs to be blocked as well. The cervical plexus block is ideal for carotid surgery or clavicle surgery.

Key Information:

Supraclavicular blocks are indicated for distal radius fractures.

References: 

Neal JM, Gerancher JC, Hebl JR, et al. Upper extremity regional anesthesia: essentials of our current understanding, 2008 [published correction appears in Reg Anesth Pain Med. 2010 Jul-Aug;35(4):407]. Reg Anesth Pain Med. 2009;34(2):134-170. PMID 19282714