I have read the letter by Mr. Smith, and congratulate him on a well articulated work. He raises interesting points from the article published by the AANA Journal in February 2013 regarding the novel technique of an ultrasound guided combination of C-5 selective root and cervical plexus catheter placement for the treatment of distal clavicle surgical pain (1). If you will permit me, I would like to address some of his concerns.
In his first paragraph he asserts that this novel technique could have “disastrous results.” I absolutely support this claim from the perspective that any regional anesthetic has the possibility of poor outcomes. Among the many such complications are intravascular, intra-dural, or intra-perineural injection; bleeding; infection; loss of motor function; and engendering serious complex pain syndromes (2). Although not specifically stated in this article, each patient should be made aware of these potential complications related to any regional technique prior to the initiation of the procedure.
The next issue I would like to address is the writer's desire to explore a detailed review of the anatomy of the brachial plexus. It is explained on page 2 of the February article that a complete detail of nerve innervation in the neck is complex, which implies that it is outside the scope of the article to review it in any great detail. The relevant anatomy is, however, presented as it directly relates to the technique in discussion. Motor and sensory innervation of the distal clavicle region is presented. This was done to lead the reader to the subsequent conclusion (specifically stated in the article) that the traditional thought of relieving distal clavicle pain with a single injection is futile because the region is covered by two separate and unique pain generators. These include the C-5 root distribution and the cervical plexus. I do agree with Mr. Smith that the imaging techniques used to produce the block could have been more richly detailed.
The issue following relates to the safety concerns regarding the possibility of dural puncture. This is another valuable point presented by Mr. Smith. The safety concern regarding accidentally infusing even a few mLs of nearly any local anesthetic solution into the dura at the cervical level (or any level for that matter) could lead to a total spinal scenario. This would undoubtedly proceed to respiratory failure, cardiovascular collapse, seizures, and potentially death. There can be no disputing that this possibility should be recognized and explained to the patient. Nonetheless, techniques of the deep cervical plexus blockade have been described for several decades, and have been accomplished safely and accurately without the benefit of ultrasound guidance (3). While the article does not specifically make this connection, the target audience may easily recognize that the C-5 root can be identified and blocked with ultrasound imaging, and can be done so with considerably less risk than blind techniques that have been described regarding this region. Notably, these blind techniques such as the deep, and intermediate cervical plexus blocks have been considered acceptable risks for years. Mr. Smith also states that regarding the illustrated method, “...this should not be done...” due to the potential complications. Complication possibilities must be acknowledged and care must be taken to avoid them with any method of regional blockade. Specific precautions for this region should include careful aspiration for not only blood, but for CSF as well.
Continuing this parsing of the issues, Mr. Smith tries to make a connection between the volume of local anesthetic used and additional distribution of motor and sensory loss. An analogy taken from Sinha, et.al., demonstrates that the possibility exists of unintentionally adding neighboring distributions during a block procedure (4). This has been a well documented nuisance complication associated with many blocks, especially the interscalene brachial plexus block. Some of the problems specifically associated with the interscalene block are directly related to unintentional migration of local anesthetic from the brachial plexus to the nearby stellate ganglion causing Horner’s syndrome. It will continue to be problematic for even accomplished regionalists. The concept that has been lost here is that the ultrasound guided technique that I describe affords the opposite outcome presented by Mr. Smith. In fact, this novel technique reports not only the first time that the procedure has been done successfully under ultrasound guidance (and with added benefit of extended analgesia delivery via dual catheters), but that its merits include increased safety and highly specific selectivity. Selectivity is a fairly new term to the regional anesthesia community. In this instance I would like the readers to understand that while a total block of an extremity alleviates the target pain, it leaves the outpatient with loss of motor function. We tend not to think about that after the patient leaves the facility. However, this patient has to continue with activities of normal living beyond our care. These activities will undoubtedly be facilitated by the gift of some motor function of a blocked extremity. It also allows the patient to report inordinate pain in neighboring distributions allowing for early detection of compartment syndrome, and possible injury from inadequate or inappropriate supportive devices. Selectivity is the future of regional anesthesia, and should be embraced whenever appropriate and suitable for the specific patient goals.
While Mr. Smith points out that the volume (8 mLs described in the article) could produce additional distribution involvement, the case reports the exact opposite. The dose reflects consideration of patient variation in anatomy and injection deposition. The term injection deposition refers to the action of the local anesthetic solution as it leaves the needle's distal opening. This deposition action is how, using ultrasound guidance, we visualize and control the placement of the local anesthetic solution around a specific nerve or fascial plane. It is important for all anesthesia providers to understand that we can no longer assign a “rubber stamp” volume to ultrasound guided blocks (e.g. adults should have 30 mLs of local anesthetic for an interscalene block). Each block and patient is unique, as is the image and deposition action. Some patients will inherently require larger or smaller volumes to accomplish a specific regional anesthetic goal. In the reported case 8 mLs were sufficient to selectively surround C-5 and produce the desired block. The reduction in volume served two purposes. The first is selectivity, and the second is an overall reduction in total local anesthetic volume. This was important considering the addition of a second catheter and the subsequent continuous infusion of local anesthetic. There are many articles reporting successful reduction of local anesthetic volume while accomplishing equally effective results, specifically in the pediatric population regional literature (5) (6) (7).
The last issue I would like to address is Mr. Smith's attempt to link two ideas together without evidence. At one point he says, “...ultrasound in itself does not guarantee a procedure's safety or efficacy. Patient safety should be the prime consideration when seeking out new procedures, and proven methods may still represent the best option.” (Mr. Smith, 2013)
Here, Mr. Smith tries to link the idea that "safety" equals "proven." It should be understood that these two concepts are mutually exclusive, and one does not depend on the other. Those readers not trained in formal logic may be lead to believe, based on this statement, that “to be safe, we must only use proven methods." That would be both an illogical, and an historically inaccurate statement. If it were true, there could be no logical explanation regarding the evolution of the regional anesthesia community into new and safer territories. While the described technique (1) is in its infancy, given the goals of increased safety and selectivity, I believe it is on a solid foundation. We have evolved from the first block successfully done by William Halstead in 1884 (8) by making careful steps toward these dual goals of safety and selectivity. All techniques were once called novel, and were met with caution and a certain degree of skepticism. So I thank Mr. Smith for his careful review of my work and his contribution to the AANA Journal. I also hope that all who are enriched by its pages will return to the February 2013 article with a broader understanding of its content.
My very best regards,
Jonathan P. Kline, CRNA, M.S.N.A. Director of Education
Twin Oaks Anesthesia www.TwinOaksAnesthesia.com
I would like to formally thank Barb Verhoff, CRNA, Deanna Kline, CRNA, D.N.P., Andy Beigner, CRNA and Jason Trudell, CRNA for their contributions of this piece.
- Kline J. Ultrasound-guided placement of combined superficial cervical plexus and selective C5 nerve root catheters: a novel approach to treating distal clavicle surgical pain. AANA J. 2013 Feb;81(1):19-22.
- Brull R, McCartney CJ, et.al. Neurological complications after regional anesthesia: contemporary estimates of risk. Anesth Analg. 2007 Apr;104(4):965-74.
- Masters RD, Castresana EJ, Castresana MR. Superficial and deep cervical plexus block: technical considerations. AANA J. 1995 Jun;63(3):235-43.
- Sinha SK, Abrams JH, Femoral nerve block with selective tibial nerve block provides effective analgesia without foot drop after total knee arthroplasty: a prospective, randomized, observer-blinded study. Anesth Analg. 2012 Jul;115(1):202-6. Epub 2012 Apr 27.
- Tran de QH, Dugani S, et.al. Minimum effective volume of lidocaine for ultrasound- guided supraclavicular block. Reg Anesth Pain Med. 2011 Sep-Oct;36(5):466-9.
- Gautier P, Vandepitte C, et.al. The minimum effective anesthetic volume of 0.75% ropivacaine in ultrasound-guided interscalene brachial plexus block. Anesth Analg. 2011 Oct;113(4):951-5.
- McNaught A, Shastri U, et.al. Ultrasound reduces the minimum effective local anaesthetic volume compared with peripheral nerve stimulation for interscalene block. Br J Anaesth. 2011 Jan;106(1):124-30
- López-Valverde A, De Vicente J, et.al. The surgeons Halsted and Hall, cocaine and the discovery of dental anaesthesia by nerve blocking. Br Dent J. 2011 Nov 25;211(10):485-7.