Reply to Dr Grocott
I would like to thank Dr Grocott1 for calling to my attention the recent report by Bhakta and Zaheer,2 in which they described the use of ultrasound-guided radial nerve blocks to inhibit the postganglionic sympathetic fibers and relieve radial arterial vasospasm.
While these authors2 used this block to correct dampening radial arterial waveforms, I certainly agree that this technique could be translated for use in the removal of an entrapped catheter. I also agree that this is a potentially safer intervention than the one my colleagues and I described,3 especially in an anticoagulated patient. Not only is this anatomical region easier to see under ultrasound, but also it would be easier to compress if a vessel was inadvertently injured during the placement of the block.
As mentioned in our report,3 our patient's radial artery was accessed by both a 10-cm 6F glide-sheath catheter (Terumo Medical Systems, Shibuya, Japan) followed by placement of an 110-cm 5F catheter (Boston Scientific, Natick, Massachusetts) over a J-wire, which reached into the patient's left ventricle. Given the length of the catheters and the refractive nature of our patient's vasospasm to conservative management, systemic and local pharmacological treatments, and general anesthesia, I am not convinced a radial nerve block would have worked for our patient. While a radial nerve block will treat vasospasm in the radial distribution, it won't inhibit the postganglionic sympathetic fibers in the axillary region.
However, I wholeheartedly agree that attempting an ultrasound-guided radial nerve block would be a great intervention prior to conducting a brachial plexus block, a general anesthetic, or perhaps even prior to other more conservative measures (lidocaine, calcium-channel blockers, nitroglycerin)! Not to mention, because an ultrasound-guided radial nerve block can be performed with a small volume of local anesthetic, if it is unsuccessful, an additional block (such as an axillary brachial plexus block) could still be performed without the risk of local anesthetic toxicity.