Anesthesiology News asked Kamen V. Vlassakov, MD, director of the Division of Regional and Orthopedic Anesthesia at Brigham and Women’s Hospital, in Boston, Massachusetts, to ask an international group of leading regionalists a series of questions of his own choosing. What follows are 11 questions for our panel of 8 experts.
Rafael Blanco, MB BS, FRCA, DEAA
Senior Consultant Anaesthesiologist
Corniche Hospital
Abu Dhabi, United Arab Emirates
Nabil M. Elkassabany, MD, MSCE
Assistant Professor
Director, Section of Orthopedic Anesthesiology
Department of Anesthesiology and Critical Care
University of Pennsylvania
Philadelphia, Pennsylvania
Jeff Gadsden, MD, FRCPC, FANZCA
Associate Professor, Duke University School of Medicine
Chief, Division of Orthopaedics, Plastics, and Regional Anesthesiology
Regional Anesthesiology and Acute Pain Medicine Fellowship Director
Duke University Medical Center
Durham, North Carolina
Rajnish Gupta, MD
Associate Professor of Anesthesiology
Department of Anesthesiology
Vanderbilt University Medical Center
Nashville, Tennessee
Yavuz Gürkan, MD, PhD
Professor of Anesthesiology and Reanimation
Head, Kocaeli University Hospital
Kocaeli, Turkey
President, Turkish Society of Regional Anesthesia
Clara A. Lobo, MD
Senior Consultant
Hospital das Forças Armadas
Pólo Porto, Portugal
Yasuhiro Morimoto, MD
Chief Anesthesiologist
Department of Anesthesia
Ube Industries Central Hospital
Yamaguchi, Japan
Kamen V. Vlassakov, MD
Director, Division of Regional and Orthopedic Anesthesia
Department of Anesthesiology, Perioperative and Pain Medicine
Brigham and Women’s Hospital
Assistant Professor, Harvard Medical School
Boston, Massachusetts
- Ultrasound (US) guidance may have transformed and redefined the practice of peripheral nerve blockade. Now, some are asking whether the pendulum has swung too far. Has it?
Dr Blanco: No, it hasn’t. The US-guided blocks have secured their place in regional anesthesia (RA), and it is now the standard tool to perform these blocks. The main mistake has been to assume that a new block equates to a new image on the screen, even if the block is the same. That has created a previously unseen interest in different groups to put on new blocks when in fact they are not even new approaches. We will end up with hundreds of blocks—renamed and rebranded—but providing nothing worth mentioning and with no evidence of superiority.
Dr Elkassabany: I do not believe so. If anything, I think the pendulum will keep swinging as the technology improves and more details can be visualized with higher resolution. The argument a few years back was that training residents in US has a downside—that they will not be familiar with use of the nerve stimulator techniques. However, use of US has become a more mainstream practice in RA, for a variety of legitimate reasons:
- There is evidence that local anesthetic systemic toxicity is decreased with use of US.
- Although we do not have evidence to support decreased incidence of nerve injury, US does afford practitioners the ability to adopt safe practices when it comes to proximity to nerves when performing nerve blocks.
- The big item that US brings to the practice of RA is consistency and an increased success rate for blocks.
- Understanding US anatomy is the key to success of nerve blocks. You could argue that knowledge of this anatomy is also the same foundation for nerve stimulation techniques.
Dr Gadsden: I don’t think that’s possible; US as a tool has elevated RA from what was, in many cases, an art form, practiced by highly skilled wizards trained in the obscure world of clicks, pops, and scratches to a specialty that is much more scientific and objective. Ultrasound continues to improve success rates and reduce complications, such as local anesthetic systemic toxicity. Moreover, it has made RA accessible to a far greater proportion of practicing anesthesiologists, thereby benefiting patients. I think what has given some of us pause with the new techniques is the ultrarapid adoption of a new block before it’s been validated. I personally attribute this to social media (“see one, do one, tweet one”) more than US, and I don’t necessarily think it’s a bad thing, as it tends to push the science—provided the science does get done. A lot of us (myself included) perform fascial plane blocks that are not yet supported by studies, but sound intuitively effective and anecdotally have led to good clinical results.
Dr Gupta: I don’t believe so. Technology tends to move forward, but there is some sense of nostalgia for older things whenever this happens. Digital cameras are by far better than any cameras that have come before today, but people still yearn for the days of film every now and then. I think US is here to stay and will continue to advance. Instead of pining over paresthesia and nerve stimulation techniques, we should be looking forward to what’s next in RA that will enhance our accuracy, precision, and safety.
Dr Gürkan: US guidance revolutionized RA practice by increasing success and safety. Nowadays, most commonly performed peripheral nerve blocks have a success rate above 90%, and in some clinics it may reach almost 100%. In this sense, US has allowed RA to be so reliable that it can almost compete with general anesthesia! Just like any method, it has limitations and may be supported by other imaging or localization techniques for blocks around central structures. Fusion imaging may be a solution if it can be used widely in everyday clinical settings.
Dr Lobo: I witnessed the change in practice in RA from nerve stimulation to US-guided techniques when I started to perform blocks using a nerve stimulator. After some time, I began to use US guidance, in 2004. In fact, clinical practice now looks more accurate and “scientific.” Previously, the skill for RA was in the hands of gurus or wizards who performed magic every time they stuck a needle in a patient. With the use of US-guided techniques, the science behind nerve stimulation came to light, and it allowed us to reduce the dose of local anesthesia, increasing safety and comfort for the patient—and, of course, confidence for the regional anesthetist. I don’t really understand what you mean when you say “the pendulum has swung too far.” Is it because nowadays there is no formal teaching of nerve stimulation techniques? I have noticed that if there is no US equipment, then there is no one familiar with nerve stimulation! In fact, one question I have is this: Should we still teach the use of nerve stimulation as a sole technique even if US is available? Anyone, at some time, can have a misadventure with US equipment, and if that person has no skills in nerve stimulation, then those particular patients will not benefit from a block they deserve. I don’t think we have swung too far, but we should be careful and prepare our residents for any clinical scenario.
Dr Morimoto: I think peripheral nerve blocks with and without US guidance are different kinds of techniques affecting safety and effectiveness. Now, I will not perform peripheral nerve blocks without US guidance. It is the same thing as central venous catheter insertion.
Dr Vlassakov: I do not think so. Ultrasound guidance is here to stay, and it is clear that its full potential has not yet been reached. US has brought improved patient safety—in trained and experienced hands—and higher procedural success. It has opened a widening window to a wealth of knowledge to the inquisitively minded. It has greatly democratized the practice of RA, making it objectively safe and accessible to more practitioners and patients. Moreover, it is having similar effects on areas such as point-of-care echocardiography. Like any new technology, US has inherent risks of misinterpretation and misuse that can only be overcome by better education and training.
- We are seeing an explosion of new US-guided RA techniques described, rediscovered, and redefined. Are we done yet, and how should we pick winners from what has been described recently as a product of intellectual misconception?
Dr Blanco: This was exactly my point from the previous question. There is a lot of misleading information right now on social media where nobody can put a filter to comments or personal views. We are seeing, just like in politics, populism in medicine. The winning block should be the one that gets a better outcome when compared fairly and scientifically, and following the mechanisms we have used for years. We must continue to use scientific methodology and avoid—like the plague—the social media masters who cannot guarantee fair play.
Dr Elkassabany: It will come down to a natural selection process and survival of the fittest. The fittest blocks will be those that are easily adopted by mainstream practitioners and can be applied on a large scale for one or more than one indication. Most of the blocks that have been described are based on an anatomic study testing the spread of local anesthetic in cadavers. Efficacy studies and clinical trials are still needed.
Dr Gadsden: It’s difficult for people to keep up with the latest block for thoraco-abdominal wall coverage, and it doesn’t help that we are relying primarily on case reports and series. We need to go back to basics and compare each one of these to a standard. For example, if you accept that the transversus abdominis plane (TAP) block has become an established and evidence-based technique for abdominal analgesia, we now need several high-quality studies comparing TAP to the quadratus lumborum block to establish superiority or equivalence. Then introduce the erector spinae plane block, retrolaminar, and midpoint transverse to pleura blocks, etc, and test rigorously against the standard. There has to be one technique that is the most reliable, effective, and safe. We probably don’t need 6 different ways of making the belly numb.
Dr Gupta: We should never be done. The methodology of science is trial and error, then repeat. We should constantly be reevaluating past norms and discovering new methodologies. Many times, people are just putting a small variation on a tried and true technique, but every now and then, this iterative process produces something new. Before we start, we don’t know which is which. The value of the collective hive mind is to run through these variations and discover what consistently works and is repeatable.
Dr Gürkan: The trend in RA practice has swung from central nerve blocks to more peripheral and as distal as possible. Yet, another problem arises, especially when the surgical field is covered by more than one plexus. Incomplete anesthesia/analgesia has led to a search for improved blocks to cover more central areas. For example, for breast surgery we started with thoracic paravertebral blocks, then pectoral and serratus plane blocks, and now erector spinae plane blocks. Despite the enthusiasm of anesthesiologists to introduce a new block every day, we need the test of time to find out which blocks will be the winners.
Dr Lobo: This explosion of new US-guided techniques is the fruit of the interest and increased popularity that RA has gained for the last 20 years. Since Kapral et al published the first US-guided block in 1994,1 the number of papers published has grown exponentially. There are numerous advantages in favor of RA, and US did wonders for improving a block’s safety. If you search PubMed for “regional anesthesia” before and after 1994, the difference is astonishing: around 39,000 papers from January 1994 until August 2017 (a 23-year interval) versus about 30,000 from 1912 to December 1993 (an 81-year interval). As long as scientific curiosity and interest are maintained around RA, there will be new blocks and approaches, etc. Only time, research, well-designed studies, and hard work will recognize the best and valuable ones—and those will prevail.
Dr Morimoto: Numerous novel peripheral nerve blocks have been named and reported. Many of them are just redefined old blocks. For example, the retrolaminar and erector spinae plane blocks are almost the same block with very different names. I think some kind of authority should evaluate all peripheral nerve blocks and classify them.
Dr Vlassakov: The contagious enthusiasm for the newly enjoyed sonoanatomy of the peripheral nerves is still raging. The main proponents behind new, rediscovered, and revamped RA and analgesia techniques are still colleagues who have been trained and have practiced without US. Educated enthusiasm, not intellectual misconception! Indeed, we should encourage and demand a good scientific approach to everything we do and change in our clinical practice. But we should remember that many of the most popular classic block techniques were initially described and went into practice with less scrutiny than what is required nowadays. And no, I am not calling for less science, just asking for these new techniques to be given a chance to prove their value in a well-conducted, time-proven course. Guidance from our own teachers, our specialty opinion leaders, and lessons from history are always useful and should be honored.
- Similarly, the definitions of peripheral nerve microanatomy and ultra-anatomy seem to be constantly revisited. How should we reconcile that with everyday practice?
Dr Blanco: This is important for me. I believe this is the way to go if we really want to understand the mechanism of action of the blocks. In the last century, people were really focused on macroscopic anatomy—it was easier to sell, but it lacked something really important. It neglected the clinical side of it. Clinical confirmation of any macroscopic finding should be mandatory; otherwise it should be considered speculation. It is in histology and in the genetic aspect of nerves where I think the successful blocks can be explained.
Dr Elkassabany: First and foremost, our motto should be, “Do no harm.” We are now pushing the envelope as to how close we get to the nerves we are blocking. The imaging technology we have today does not allow us yet to get down safely to the detailed, microanatomy level. Each practitioner should continue to adopt the recommended practice guidelines to guard against nerve injury. Some of these guidelines include avoiding overzealous sedation, paraesthesia, and high injection pressure.
Dr Gadsden: When reading about layer A versus layer B, and what new and confusing name is being applied to each, it is important to consider the implications for safety. An excellent example is the interscalene brachial plexus block. We know that whether you place the local anesthesia between the middle scalene and plexus sheath (periplexus) or between the hypoechoic roots (intraplexus), the onset time is the same. In other words, there is little clinical advantage to putting your needle so close to the roots. However, the intraplexus approach appears to confer a risk for subperineural spread of injectate (something that we all can agree we wish to avoid), whereas the periplexus does not.
Dr Gupta: We take an anatomic understanding and translate that into what we observe in clinical practice. Frequently, there is a set of assumptions inherent in that translation. These assumptions can render certain scenarios as being inconsistent with the model. New evaluations of anatomy, physiology, and pharmacology are needed constantly to ensure all scenarios are consistent with the observed clinical patterns so that ultimately we can predict outcomes instead of reacting to them. For example, why certain adjuvants lead to nerve dysfunction and why this varies from block to block is not entirely understood.
Dr Lobo: This is a very difficult question to answer. Everyday technology advances, and we have new and better equipment at our disposal. Companies are very committed to developing more advanced US machines that are more portable, powerful, and user-friendly. We realize that better images give more detail and information about the peripheral nerves and surrounding structures. Who knows what the future holds. We will be able to see even smaller nerves, with higher definition.
Dr Morimoto: The recent development of peripheral nerve microanatomy has revealed the detailed structure of a sciatic nerve. So we inject local anesthetics into the common perineuronal sheath. This was avoided before because intraneuronal injection could induce neuronal damage. In a case where the peripheral nerve microanatomy is confirmed by US, we should take advantage of the results.
Dr Vlassakov: This is still a developing scene. Surprisingly, after studying human anatomy for ages, we are still discovering and redefining a lot about peripheral nerve micro- and ultra-anatomy. And some of the newly described micro- and ultrastructures and terminology need to be reconciled very soon by the experts, as we continue identifying discrete features of neuroanatomy in greater detail. Improved imaging technology will likely provide more food for thought—and pose more questions to be answered.
- Should we create a separate category in regional anesthesiology for all the tissue plane/interfascial blocks?
Dr Blanco: Yes, we should because they are not based only on macroscopic anatomy. The fascial blocks that we do are very effective for myofascial pain, and that is microscopic. Regarding local anesthetics, the distribution is also important. A fascial plane block can distribute in 2, 3, or more fascial planes, therefore changing the point of injection to all those fascial planes, but in the endthey are the same block. Fascial plane blocks as a category should definitely be created, but this has to be monitored by people with a proper understanding of topographical anatomy and injectate distribution.
Dr Elkassabany: Eventually we may need to do that. Currently, these blocks are being described and developed. Some of these blocks will survive and find their place in practice, and others will fade away because of limited utility. The phenomenon that is really interesting nowadays is that some blocks are first described, and only then do we start to look for indications to fit the blocks. It fits the idiom, “putting the cart before the horse.”
Dr Gadsden: This would probably be useful, if only for the fact that, as a group of block techniques, you use a slightly different set of skills. For example, landing a needle tip in the correct intermuscular plane, ensuring correct “peeling apart” or “unzippering” of the muscles or fascial layers, and manipulating the needle as you inject to ensure the correct degree of spread, is much different than the skill needed for a single-injection femoral or median nerve block.
Dr Gupta: There may be value to this. Some of the safety standards around peripheral nerve blocks are based on the needle and local anesthetic/adjuvant being delivered directly adjacent to a nerve and blood vessels. However, the targets for tissue plane blocks are frequently distant from the actual nerve. Therefore, should the standard that blocks not be performed under general anesthesia to ensure paresthesia as a marker for nerve proximity apply to tissue plane blocks as well? Do we need nerve stimulation ever in these blocks? Are the same quality of ultrasounds and needles required for tissue plane blocks? Do we still need to use blunt, B-bevel–style block needles for these blocks, or can we use less expensive alternatives? What are the anticoagulation and antiplatelet concerns for tissue plane blocks? Having these as a separate category may break us from our rigid definitions of peripheral nerve blocks.
Dr Gürkan: Tissue plane blocks could be categorized as upper thoracic and lower abdominal blocks. Yet some of the upper and lower extremity plexus blocks—like the cervical plexus block or Shamrock block—could also be considered interfascial plane blocks. A classification may help understand both the mechanism of action and block dynamics and dosing of local anesthetics.
Dr Lobo: There has been some misinterpretation and misconceptions regarding anatomy and nerve block techniques. That is a fertile field for confusing terminology, categories, and block anatomic definitions. The most blatant example is the quadratus lumborum block2—it sounds like a TV series—and the adductor canal block versus the subsartorial approach.3 There is an editorial discussing this point, written by Boezaart.4 Discussions with anatomists could help better categorize block approaches and reach a common, more consensual standard.
Dr Morimoto: No, I think there are two kinds of peripheral nerve blocks. The one is targeted around the nerve, and the other one is a tissue plane/interfascial block. However, the border of the two types of block is unclear. But I do not think that the new category is necessary now.
Dr Vlassakov: I believe so. Discrete and carefully targeted tissue plane blocks are neither simple infiltrative techniques nor true major peripheral nerve blocks. Their advantages and limitations, associated risks, and pharmacokinetics and dynamics would differ and need careful scrutiny and better definition. Yet they have been effectively in use and with good results, so we have to verify, explore, and modify when necessary as we go. It is so hard to keep up with these dynamic times!
- What will the next breakthrough(s) be—new local anesthetics? New nerve-finding technology? Alternative analgesia methods?
Dr Blanco: In my opinion, the breakthrough will be the use of drugs directly into the sympathetic and parasympathetic systems.
Dr Elkassabany: All of the above. I think the most imminent breakthrough will be discovery of a safe formula of long-acting local anesthetic that may substitute in part the use of nerve catheters in some blocks. Even then, I think nerve catheters will still have value in certain blocks. Better yet, how about discovery of another way to deliver local anesthetic around nerves? The use of nanotechnology has been described in animal models as local anesthetics have been tagged with some magnetic markers and were kept in place with a magnet applied from outside the body. Another technology that is being tested is the use of peripheral nerve stimulators for acute pain management. Ultrasound technology is also evolving, especially in imaging of deeper structures, which may even revolutionize the practice of deeper blocks. We already have some machines coming up with single piezoelectric crystals that are excellent for generating high-definition imaging of deeper structures. I also predict machine-learning technology combined with GPS technology to facilitate US identification of anatomic structures and to make driving a needle to the desired target much easier. Also, in terms of needles and catheters, I think the next generation of catheter-over-needle will avoid some of the common problems currently associated with this technology.
Dr Gadsden: The Holy Grail in RA for facilitating rapid recovery is to provide 1) high-quality sensory analgesia of a discrete area with 2) no motor block for 3) an extended duration of time (ie, days to weeks). This may be achieved with novel local anesthetic formulations, and several are in use or in development. There is also some excitement around technologies, such as percutaneous nerve stimulation, where thin microleads can be left close to the nerves and an electric current applied that interferes with conduction of sensory (but not motor) signals. These can be turned on and off at will and, depending on the location or surgical procedure, can be placed preoperatively and left in place for weeks.
Dr Gupta: All of the above. These are not mutually exclusive innovations. If we find a local anesthetic that provides sensory block without motor block and has extended analgesia, then that would be a breakthrough. If we find a more refined way to localize nerves and minimize the one major remaining risk of peripheral nerve blockade, nerve injury, that would potentially increase the number of patients who would get RA. And if we find a simple oral or IV way to provide analgesia that never requires RA but doesn’t carry the heavy burden of opioids, then I am happy to never have to do regional again. We should always be cheering for the next innovation that makes the clinical care of our patients more effective and safer.
Dr Gürkan: Progress both in pharmacology and technology will certainly offer us new toys and will allow us to practice RA in a very precise way. Local anesthetics with specifically desired durations of action and improvements in nerve localization techniques to allow us be more accurate will surely improve safety.
Dr Lobo: There is so much new information and data that it gets really difficult to understand what might follow, but I can try some “futurology”! Technology is evolving as we speak, and new and more powerful equipment will be developed. Probably in the near future there will be equipment that will allow us to understand microanatomy and, maybe, functional anatomy. I think that identifying the nerve structure before injecting could be of benefit, because then intraneural injection and possible nerve damage would be avoided. There is a recent local anesthetic formulation that is still under study for RA: liposomal bupivacaine.5,6 New forms of drug administration can also be introduced. Personally, I would love it if a local anesthetic reversal agent would be developed!
Dr Morimoto: We need longer-acting local anesthetics for the next breakthrough. Exparel (liposomal bupivacaine, Pacira) might be the one, but it is not available worldwide. We also need local anesthetics without motor nerve effect. For postoperative analgesia, a sensory nerve block only would be ideal.
Dr Vlassakov: We are looking forward to long-overdue breakthroughs in all these directions. There has been a significant stagnation in introducing new agents to clinical practice in RA, and anesthesiology in general. We do need more nociceptive selectivity and controlled duration, allowing for a range between ultrashort (several hours) to ultralong (days to weeks) block action. Nanotechnology could be useful, but it is yet to deliver in our field. Imaging technology will continue improving gradually, but a disruptive innovation in the field is always possible and welcome, including something easily available at bedside, like nonionizing fusion technology. Nonpharmacologic analgesia should also be a focus of our innovative studies and practice—from selective peripheral nerve stimulation, revisiting the gate theory, through (self)-hypnosis and preconditioning, to traditional medicine. All directions should be explored separately and in unison. Patient pretesting, stratification, and design of individually tailored analgesia, dynamically reassessed and modified, may offer significant benefits but could be prohibitively time- and resource-consuming for general practice.
- What are the biggest challenges to achieving effective opioid-free perioperative analgesia?
Dr Blanco: To make people understand that nociception is not the answer to everything and that the approach has to be multimodal.
Dr Elkassabany: Challenges to these goals come on multiple fronts. One of the bigger challenges is patient education and setting patient expectations correctly in terms of identifying the magnitude of postoperative pain and how to deal with it. Another challenge is to get buy-in from other perioperative care providers. In some institutions, financial constraints may be imposed by pharmacy and hospital administrators before adopting some of the new niche drugs into a multimodal care pathway. The other point that we have to make clear is that we need to be careful with glorifying the term “opioid-free analgesia.” It is an excellent goal, but my point is that we should not demonize opioids. I think opioids definitely have a place in postoperative analgesia as long as they are used appropriately.
Dr Gadsden: We have all the pharmacologic tools to conduct opioid-free perioperative analgesia, but the two biggest barriers come from the patients themselves. Expectations regarding pain management have to be precisely managed and reinforced. An opioid-free experience is likely to be one where there is some discomfort, but that discomfort will be manageable and the patient has to be an active partner in a pain management plan. The other big barrier is the high prevalence of patients arriving to the hospital already taking substantial doses of opioids. These are notoriously challenging cases to manage. We have been trying to divert these patients preoperatively to a specific perioperative pain management clinic where they can be weaned to a more manageable daily dose, but tapering the dose to a level that makes a significant difference is often elusive.
Dr Gupta: This is partly a major cultural change in the United States—and is becoming one in many other countries as well. First is the perspective of patients. The expectations of what pain management is will need to change. We’ve made patients believe that taking a pill will make them have no pain. That is no longer true. We have to work harder at this and use more complex plans for pain control. Our surgical colleagues must also discuss reasonable pain expectations with the patients when they are planning their operations. Telling a patient that they will have no pain as a reassurance will not be conducive to an appropriate team effort. As anesthesiologists, we must continue to educate ourselves and implement advanced nonopioid, multimodal strategies for pain control to get patients on the correct footing in the perioperative period. And finally, a societal effort to redo opioid prescribing legislation, which facilitates short courses of postoperative opioids when necessary, is a hurdle that will get us on the right path.
Dr Gürkan: Multimodal analgesia and enhanced recovery protocols will allow both recovery to be faster and analgesia to be more complete for our patients. Yet, there may still be some limitations when surgery or the source of pain is too excessive, and the performed RA may have limitations due to multiple injections and risk for local anesthetic toxicity.
Dr Lobo: I am aware of the big problem of opioid addiction developing after opioid prescriptions in the United States.7 The use of multimodal analgesia can reduce opioid consumption.8 There is no significant association between the type of surgery (5.9% for major surgery vs 6.5% for minor surgery) and the development of addiction. The use of RA is marginal; regional techniques are used for severe pain conditions between 1.13% and 12.5% of the time for conditions such as rib fractures9 and hip and knee arthroplasties,10 respectively. We can do so much better.
Dr Morimoto: First, I am not particular about opioid-free analgesia. Although perioperative opioids may increase the incidence of PONV (postoperative nausea and vomiting) and might suppress the immune system to allow cancer recurrence in the future, I think appropriate doses of opioids are necessary. Of course, overdoses of opioids should be avoided, and we should seek to reduce the dose of opioids by using other analgesic methods, including peripheral nerve blocks. If someone wants to achieve opioid-free analgesia for abdominal surgery, then abdominal wall blocks, including TAP and rectus sheath blocks, will decrease the postoperative use of opioids. But these blocks can block abdominal wall somatic, not visceral, pain. The development of an abdominal interfascial block, including the quadratus lumborum block, which can block visceral pain, should be considered.
Dr Vlassakov: I see in opioid-free perioperative analgesia an inspiring higher goal, but not the ultimate self-serving result we are seeking. It is just like pain-free surgery. We actually aim at controlled, easily tolerable discomfort that does not interfere at all with functional recovery, and that at the expense of minimal to no side effects. And safe, goal-oriented, procedure-specific, and patient-tailored RA will be a pivotal part of the solution. We still have some hard work ahead of us in order to consistently provide better and earlier access to optimal analgesia, including peripheral nerve blocks. And that is only one aspect of our interconnected multidisciplinary patient care goals. So, the challenges range from logistical (insufficient access to advanced expertise 24/7, high cost of individualized care, etc) to scientific (incomplete and developing understanding of the underlying pathoanatomy and pathophysiology of perioperative injury, healing and recovery, etc).
- How would you define multimodal analgesia? And could that simply be an excuse and mitigation for the imperfect block(s)? Steroids? Gabapentin? What other agents would you use? When and how?
Dr Blanco: Multimodal means to me that pain is caused by different mechanisms with different degrees of penetration, depending on individual variability and varying procedures. All the mechanisms have to be addressed for each procedure.
Dr Elkassabany: The definition is obvious. The answer to the question of whether it is a way to mitigate an imperfect block is no. Multimodal analgesia embodies the concept of an acute pain medicine practice. I believe that we are a group of acute pain medicine physicians who are skilled in RA. I always view RA as a means, not an end. The end goal should be optimizing patient outcomes and improving their perioperative experience. Sometimes, some of the techniques we do will not cover every source of pain, but they will still help us to achieve our goals with the help of other components of a multimodal analgesia protocol. The example that illustrates this concept is comparing the adductor canal versus femoral nerve block for analgesia after total knee arthroplasty. We have exhausted the question whether both blocks are equally efficacious from the analgesic standpoint. However, at the end of the day, we should think about the bigger picture and the goals of perioperative care. Does it really matter if one block is a little better or worse when compared with the other block? The answer is probably no, as long as the patient does not have increased analgesic needs and the block is done as part of a multimodal analgesia protocol. This is especially important as one of the two blocks offers some other advantages, as in better physical therapy and functional outcomes since quadriceps muscle power is preserved.
Dr Gadsden: Multimodal analgesia employs the use of a wide variety of nonopioid agents to reduce the dose and side effect profile of any one group of agents, but particularly opioids. We routinely use acetaminophen, NSAIDs (nonsteroidal anti-inflammatory drugs), and gabapentinoids around the clock throughout the discharge period; ketamine 0.5 mg/kg up to 40 mg as a single bolus before incision; and IV dexamethasone 10 mg both intraoperatively and again at 24 hours. We also routinely use tranexamic acid, not just for its blood-sparing effect but as an analgesic through prevention of pain related to hematoma formation. There is no question that when we are using blocks that imperfectly cover the surgical site—and adductor canal block for total knee arthroplasty is a prime example—the multimodal regimen is critical to the success of our analgesic plan.
Dr Gupta: Pain is a complex physical, psychological, and emotional phenomenon that has as much to do with the physical trauma causing the pain as the coping mechanisms, personal pain history, and social support the patient has in dealing with the pain. Even a completely functional block may not address the entire source of pain, cannot reach every region of pain in a multitrauma situation, and eventually must be discontinued before the entire pain experience is resolved. Multimodal analgesia, at its basic level, means the use of multiple avenues of pain control to maximize the analgesic benefit of each individual modality and receptor pathway, while minimizing the side effects of each of those modalities. However, it should also include the plan for dietary advancement, physical therapy, perioperative temperature control, infection management, and psychological aspects of recovery. As anesthesiologists move further into the entire perioperative area, we have to consider more of these nonpharmaceutical components of the analgesic regimen in order to continue advancing our patient care.
Dr Lobo: As I said in the previous question, clear guidelines have been published that advise the use of multimodal analgesia in order to reduce opioid consumption and their adverse effects.8The fact that a particular block is not covering the whole area involved in the pain experience does not mean it does not work. For example, knee surgery is not totally covered by the femoral block. We need to include some other drugs (acetaminophen, NSAIDs, etc).
Dr Morimoto: If the peripheral nerve blocks completely block the pain from the surgical field, no other analgesic drugs would be required. But the “block effect” time is limited. Use of NSAIDs and acetaminophen after surgery could reduce the pain after the block effect has disappeared. We routinely use IV acetaminophen after surgery, in most cases with peripheral nerve blocks for one day. The use of oral NSAIDs is also recommended, and more PCA (patient-controlled analgesia) morphine or fentanyl to back up the nerve block effect should be considered.
Dr Vlassakov: A failed block is a failed block—that is relatively easy to demonstrate. Moreover, a target could be missed, and sometimes the intended target could be wrong or insufficiently well defined. For example, the benefit of blocking just two-thirds of the surgical field, including the various anatomic layers of surgical intervention/injury, could be seriously questioned. It is highly unlikely that the challenges of “ideal” perioperative analgesia are adequately met by a single method or drug. It’s similar to modern anesthesia. From a single agent (ether or chloroform) to carefully balanced polypharmacy in use today, our modern analgesia regimen will continue to employ a variety of agents, addressing specific goals and needs, and possibly at different times during the perioperative period. All of the medications listed above and more have proven some efficacy. We need to continue exploring, learning, optimizing, and remaining open-minded and be able to offer alternatives. That is what multimodal means to me.
- Should effective RA blocks be combined with local infiltration by the surgeon? When should we start worrying about the total local anesthetic dose, and how do you best factor in the time between injections?
Dr Blanco: I see nothing wrong in surgeons directly infiltrating local anesthetic in the surgical field as soon as they do not have to worry about disrupting their view or technique. We have proved in recent years that very low local anesthetic concentrations can do the job perfectly well. We should always be worried about scenarios where people involved don’t know what is meant by LAST (ie, local anesthetic systemic toxicity) and how to recognize it and treat it.
Dr Elkassabany: Why not? It is never mutually exclusive. I always tell our residents and our surgeons that the more we put local anesthetics into different places, the better.
Dr Gadsden: The evidence supporting local infiltration analgesia is not terrific, and like many of the technical procedures we do, such as nerve blocks, it probably comes down to technique. The fact is that if you want to use 200 mL of local anesthetic to fully anesthetize a large joint, you cannot simply squirt it in willy-nilly. It takes time, patience, and an excellent understanding of the small nerves and their course surrounding the joint. When done well, local infiltration analgesia works well. When rushed or left to the orthopedic residents to shovel in at the end of the case, results are underwhelming. I favor an “either/or” plan: If the surgeon insists on performing local infiltration analgesia, that’s fine, and I’ll skip the nerve blocks. That’s assuming that he/she is doing a good job. We were able to successfully “relieve” our surgeons of this task by showing them that not only would their intraoperative times be reduced, but their patients would have longer ambulation distances, fewer days in the hospital, and a higher discharge proportion to home (vs a skilled nursing facility) if we did adductor canal catheters and posterior capsule infiltration compared with their local infiltration analgesia technique. Once they saw the benefits, they gladly handed all the locoregional procedures back to us.
Dr Gupta: There is no clear definition and guidance on the total dose of local anesthetic given when local anesthetic doses are delivered in different locations and at different times. Ultimately the peak plasma concentration of the local anesthetic is the component that drives the toxicity. The conservative management strategy is to use the published total local anesthetic doses regardless of where the dose is delivered, as the absorption and plasma uptake can still occur. However, this approach is probably overly conservative, and there have been observations in the past where double the published “max” dose has still not produced high plasma concentrations. Until further studies are performed, clinical judgment and vigilance will still be required.
Dr Morimoto: In our hospital, local infiltration analgesia by the surgeon and continuous femoral nerve block are used for total knee arthroplasty. Before surgery, we insert the femoral catheter with small doses of local anesthetics. Then the surgery is performed under general anesthesia. Local infiltration analgesia by the surgeon is performed during the surgery. The continuous infusion of local anesthetics begins after the surgery. By this method, we do not have to perform a sciatic nerve block. This enables us to check for possible common peroneal nerve injury after the procedure. Continuous femoral nerve block could provide the analgesia after discontinuing the local infiltration analgesia. So I think the combination is useful. One problem is the large amount of local anesthetic dose, which might induce systemic toxicity. But I think the different injection times should decrease the risks.
Dr Vlassakov: I encourage surgical infiltration in combination and synergy with peripheral nerve blocks, but that needs to be done in a seamless coordination with the surgical team performing the infiltration. Total doses and timing need to be carefully orchestrated, and we, the anesthesiologists, should continue to play the critical role of clinical pharmacologists perioperatively. For example, if I perform a preoperative adductor canal block for total knee arthroplasty, I allow and encourage the surgical team to use their usual infiltration 2 to 3 hours later; or, if the procedure takes only 1 hour, I would ask them to give half of the dose (either in volume or in milligrams), mostly targeting the posterior and the lateral aspects of the knee joint capsule. The total doses have to be carefully examined. We have some more work to do as a subspecialty to better define the dose/time/redose paradigm. While such an approach would be considered confounding in an experiment or a clinical trial, we need not hesitate to combine various methods of analgesia, despite the claim of “ownership”—this should, but does not always, come naturally in a real patient care team.
- What is your opinion on the coapplication of adjuvants with traditional local anesthetics for peripheral nerve blocks? Which one(s) do you use routinely and how?
Dr Blanco: I am really interested in this subject, but I am still not using them.
Dr Elkassabany: I am a supporter of adding preservative-free dexamethasone to my single-shot injection, especially when prolonged analgesia is desired. The next part of my answer may be biased and not really evidence based, but it may be that adding dexamethasone might blunt the rebound pain phenomenon after resolution of the effect of a peripheral nerve block. This is mainly based on personal observation and clinical anecdotes.
Dr Gadsden: There seems to be a limited role for these adjuncts. Both dexamethasone and dexmedetomidine, for example, appear to extend the duration of sensory blockade, but only by a few hours. To my way of thinking, I want my duration to fall into 1 of 3 categories: short (eg, 4 hours for an arteriovenous fistula creation; I’ll use mepivacaine for this); long (eg, 4 days for total shoulder arthroplasty; I’ll use a catheter for this); or medium (12-18 hours). This last category is the hardest one for which to find applications. One example where I’ll use adjuvants is when the surgical procedure doesn’t really warrant a catheter, but it’s 2 pm and I don’t want my ropivacaine wearing off in the middle of the night. In these cases, I’ll use bupivacaine with dexamethasone (2 mg) and 1:400,000 epinephrine in the hope that I can squeeze another several hours out and get that patient a good night’s sleep.
Dr Gupta: The hope for single-injection RA is to provide longer pain relief with a simple technique and minimal side effects. The use of adjuvants is an attempted means toward this goal. However, I believe that adjuvants are frequently unpredictable and can introduce their own side effects and complications. Epinephrine has not been shown to enhance analgesia significantly and can still function as a vascular marker, but I frequently do not include it in my blocks. Dexamethasone has so many mixed results of added analgesia and side effects that I do not use it routinely. Clonidine and dexmedetomidine are showing increasing value as adjuvants for both enhancing analgesiaand keeping side effects to a minimum. I will use clonidine at times in my blocks, but not routinely. Other adjuvants have not shown much benefit, in my opinion. Most of my single-injection regional anesthetics are performed with ropivacaine without adjuvants. If I need a longer block, I will typically place a catheter instead.
Dr Lobo: It is not normally something that I do, mixing local anesthetics and additives. If I need to prolong the block, I prefer catheters.
Dr Gürkan: In my clinical practice, I don’t prefer to use additives because many of them are not approved for that purpose. Adding other drugs to local anesthetics may lead to potential drug errors, too. Only a few of the additives have proved to be effective and beneficial for the patient. Liposomal bupivacaine may eliminate the need for additives.
Dr Morimoto: Some adjuvants are used to boost the effects of local anesthetics. Some of them have been reported as effective in increasing the duration of nerve block. These adjuvants are also effective by systemic injection. In this case, the adjuvants should be used systemically not as an adjuvant—that is, not used with local anesthetics. By now, the neurotoxicity of these adjuvants has not been evaluated. We use 3.3 mg of dexamethasone systemically for patients managed with general anesthesia and peripheral nerve block. The dose of dexamethasone is effective in preventing PONV and providing a weak boost to the peripheral nerve block.
Dr Vlassakov: This is still an area of ongoing research, of course. And the jury is still out. In our group, we mostly use dexamethasone (2-4 mg in 20-30 mL of local anesthetic) but have also trialed clonidine, buprenorphine, and, more recently, dexmedetomidine for various blocks and with variable results. Logically, we need to be prepared for the delayed (10-20 minutes after injection) additive-specific side effects from their predictable systemic absorption. For example, the sedation with minimal to absent respiratory depression could be a welcome anticipated effect of dexmedetomidine.
- How about RA on awake or asleep patients? What is your take on this controversy, and how do you practice?
Dr Blanco: It is based on the patient’s preferences. I normally perform everything awake, but I have a very low threshold to provide sedation to patients at any stage of a procedure. Providing my patients with a pleasant experience is a must throughout their operation and postoperative recovery.
Dr Elkassabany: Awake/sedated unless otherwise indicated.
Dr Gadsden: Objective monitors, and especially US, have challenged the dogma of “never do a block asleep,” and asleep blocks are a common part of my practice. The case series of spinal cord damage after asleep interscalene blocks that put so many of us off this practice is just not relevant with today’s technology. We can see and stay away from nerves—to the best of our ability—using US. We use electrical nerve stimulation to ensure that we are not evoking a motor response at dangerously low currents (<0.2 mA), which would suggest intimate nerve contact. Finally, we now have injection pressure monitoring, which warns us of an inappropriate needle-tip position (eg, intraneural). Blocks in asleep patients—or those who cannot report sensory feedback, such as those who have already received a spinal anesthetic—are often done for patient comfort and/or safety. For example, in a flailing child or trauma patient, performing the block asleep under controlled conditions with the above-mentioned complementary objective monitors represents a much safer practice than struggling to place a needle in an uncontrolled patient while awake.
Dr Gupta: I think it is time to revisit this controversy. I think there are blocks that are performed under US guidance that likely are not more risky while the patient is asleep and often can be performed more safely, as the patient does not have to be excessively sedated. I think the pediatric RA experience provides some guidance on the use of asleep RA techniques and their safety. There are many adults who don’t get RA because of fear of the procedure. At the moment, we still perform most of our blocks for adults awake, but we will be exploring performing abdominal wall blocks asleep in the near future. The other big hurdle with asleep RA is the added time in the operating room, which reduces the efficiency of a parallel functioning block service.
Dr Gürkan: I prefer to perform RA on awake patients, and I consider it safer for the patient. Sedation and analgesia can be provided to improve patient comfort. Awake patients definitely allow for a degree of clinical neurologic monitoring. On the other hand, in pediatric cases, or in accordance with a patient’s wishes, blocks can be performed in sleeping patients as well. Withholding nerve blocks would result in too much pain, requiring too much systemic analgesia.
Dr Lobo: Personally, I prefer awake patients. But it is important to realize that some surgeries require difficult and uncomfortable positioning and can be quite long for an awake patient to tolerate, unless he or she is very motivated. I try to respond to the patient’s wishes, if there are no contraindications.
Dr Morimoto: For brachial plexus blocks, we routinely perform them in awake patients. Pain and paresthesia during the procedure are still good indicators of block needle and peripheral nerve contact. This is the same thing for femoral and sciatic nerve blocks, including the lumbar plexus block. For trunk blocks including TAP, rectus sheath, and paravertebral blocks, awake or asleep does not matter.
Dr Vlassakov: I remain a proponent of awake to lightly sedated RA when we are referring to major nerve blocks (sciatic, brachial plexus, etc), as we do not have a great surrogate for physiologic neuromonitoring and no one can be always absolutely assured about anatomy variations and or suboptimal target/needle visualization. That said, I would not deny necessary treatment to a patient who really needs RA, but would refuse awake injection even after careful discussion of the risks and benefits. After informed consent and explanations of the somewhat increased risks, I would proceed using all available monitoring techniques, including nerve stimulation (when applicable) and opening pressure monitoring, and I would not delegate this block to a supervised trainee. For tissue/interfascial plane blocks (eg, TAP, pectoralis, fascia iliaca, proximal intercostal blocks, etc), I feel very comfortable performing the injections asleep, using the usual precautions and under standard ASA (American Society of Anesthesiologists) monitoring.
- How should we teach and learn RA today? What are your tips?
Dr Blanco: Learn first and filter who your teachers are. There are now thousands of self-proclaimed teachers and experts. A bit of caution by a young doctor is needed. Stay away from storytellers and stick to the ones with a million doubts. Study and question everything; think and rethink why what you were told is written in stone; love your job; never give up; and share and talk with your colleagues.
Dr Elkassabany: Always be open to learn new techniques; read and stay up-to-date; be humble. You are not above any task you are asking your trainees to do; essentially, always lead by example. Mixed-reality simulation will be huge, and for that we are just scratching the surface. Make your trainee part of the decision making during pain rounds, and listen to their point of view.
Dr Gadsden: For high-stakes interventional procedures where we are directing needles toward vulnerable nerves, vessels, and pleura, there is great value in ensuring that trainees have practiced the motor skills on a simulated patient. This provides them with the opportunity to “surf” the learning curve in a risk-free and relaxed environment, while developing the hand–eyecoordination necessary to drive and find the needle and targeted structure. There are a wide variety of simulators available, from simple meat and gel phantoms to sophisticated 3-D thoracic paravertebral computerized systems. Whatever the system you use, trainees should have demonstrated a certain competency with US and the needle, and be able to correctly identify anatomic and sonoanatomic features before placing the probe on a patient.
Dr Gupta: Education in medicine is changing rapidly. Educational material can be found in textbooks, lectures, online videos, podcasts, workshops, and social media. There is no shortage of information. The challenge for the future is finding the best information and presenting it in a coherent manner. Technical skills, such as performing RA, need to add another layer of modernization. Simulation technology is improving with better simulation models and virtual RA simulators to allow the learning regional anesthesiologist to gain some experience in the technique before performing a risky procedure on an actual patient. A combination of tactile, physical models with virtual simulations is probably the best way to gain some dexterity in RA without practicing on patients. Educators should embrace this new technology and pair it with all the educational resources available to the student.
Dr Gürkan: RA is more than sticking nerves! It requires understanding anatomy, block dynamics, pharmacology, and judgment of the medical status of the patient, too. Just like using video laryngoscopes for intubation, US allowed us to see and monitor what the trainee and the educator are doing. Books and internet sources are available for those who want to study the background. Younger generations learn very fast, and basic blocks can be performed by anyanesthesiologist with proper training. In different parts of the world, I still meet people who cannot find instructors in their nearby geographic region. And yet, knowledge always spreads faster than we can imagine.
Dr Lobo: We are in a continuous process of learning. I always learn something new in every workshop/meeting that I participate, either as an attendee or as faculty. The main issue is to be curious and aim for better performance and acquire better skills. If you are really motivated, you will find a way to learn. There are several courses, meetings, e-materials on websites and YouTube, and books especially dedicated to this subject. The issue is to choose the best way to learn that fits your capabilities.
Dr Morimoto: An old Japanese saying is, “Show them, tell them, let them try, and give them compliments, or they don’t do anything.” I think this concept is still important in this new age. First, I show my best performance to trainees. Then I let them do it with my guidance. After that I let them do it alone. Recording the block procedure and watching it with the trainees after the procedure is over is also important. And do not forget to give them compliments.
Dr Vlassakov: We should continue to cherish and promote our love for our subspecialty with curiosity and passion and by example. We need to keep up with the dynamics of new technology and new learning methodologies. We also need to adjust to generational changes and inspire our younger colleagues to excel and push our science and practice further. Development, validation, and incorporation of dynamically updated learning curricula with some targeted individualization present worthy challenges to be urgently met. Perpetual skill assessment in our field of training and learning needs a lot of work, as well as developing better high-fidelity simulation media and environments for RA.
References
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