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FAQ

ACUTE PAIN MEDICINE
Do you use cervical epidural anesthesia for CEA surgery?
Answer: Very few people have experience of or need for that. We would intuitively think it is overkill for CEA surgery, although we have used it with great success in patients with terminal cancer; breast cancer for example. We have routinely used single-injection high cervical paravertebral blocks (C3/4) performed similar to low cervical paravertebral blocks (Anesth Analg 2005; 101: 1885 – 1886). These blocks work very well and take the danger of injury to the vertebral artery out of the equation. With high cervical epidural block, the phrenic nerves could both be threatened. Please see Buchheit et al. Reg Anesth Pain Med 2000; 25: 313 – 317 for a good reference on cervical epidural block. .
Question: What do you do about the posterior pain associated with total knee arthroplasty?
Answer: This is an interesting question. It is known that patients with a range of motion of, say 10 – 90 degrees preoperatively suffer more posterior pain than patients without flexion contractions. The modern thought is that the pain is due to hamstring stretching and the posterior knee capsule is not that much of a pain generator. For those patients, we would do subgluteal sciatic nerve blocks if they need it postoperatively. There is, however, a price to pay for this, because it becomes more difficult to mobilize patients with hamstring and quadriceps paralysis. This phenomenon is also being studied at present. For the other patients with 0 – whatever range of motion without flexion contractions we do IPACK blocks. (See here)
Question: Do you have any experience with PCRA for continuous femoral blocks?
Answer: Yes, we love it. (We assume with PCRA you mean patient-controlled regional anesthesia). We do it all the time. Use a background infusion of say 3 – 5 mL/h of 0.1 or 0.2% ropivacaine and then add patient controlled boluses of the same drug every 60 minutes. Having said that, we have lately found on our ambulatory TKA patients that very few of them use this facility given a perfectly placed sub0circumneural continuous femoral nerve block.
Question: Do you send patients home with blocks after major shoulder surgery?
Answer: Absolutely. We have a very active and mature ambulatory program, but we follow strict protocols (see here . Ideally, we ask the Home Nursing services to follow the patients at home, but for years we have followed the patients telephonically and the patients’ caregivers remove the catheters without any problems. It is, however, very labor-intensive and poorly remunerated, but this is a very popular program and there should not really be any other reasons not to do it. For example, in our institution at UF, where they do many reverse total shoulder surgeries, the hospital stay came down from an average of 7 days to just over one day over 10 years of doing this. For hips and knee, it is a bit different, but we rely heavily on Home Care Nurses and PT/OT’s to follow the patients at their homes. The hospital stays came down from around 4 days to an average of just under two days in our busy arthroplasty program. About 20% of patients for shoulder, hip and knee arthroplasty go home from the recovery room.
Question: How do you manage the older frail patients with hip fractures?
Answer: These patients are most often at their best health condition the second just before the injury. From there, they go downhill fast. So, we try to do their surgery as soon as possible. Ideally, we place a femoral nerve catheter as soon as we can. The ER is the ideal place for this. This takes pain out of the equation, and it makes work-up with X-rays etc., easier. When the patient reaches the OR, we place them on their sides, which process is now pain free due to the femoral block, and we do a single-injection or continuous spinal block. Continuous spinal block is our preference because we can then carefully titrate the spinal block to its effect and we can keep the spinal block going with small repeated doses over a relatively long time. This has about no hemodynamic implications and almost no patient is too sick to do like this. Remember to tunnel the femoral catheter away from the hip where the surgeon has to do his magic.
Question: I know this is not specifically for RAEducation.com. but please tell me about the APS Preceptorship presently presented at UF?
Answer: Thanks for the inquiry. The preceptorship is to allow practitioners to become familiar with the functioning of a contemporary Acute and Perioperative Pain Medicine Service. Of course, we would tailor your exposure to your particular interests, however, a full exposure to our APS is best served by spending at least two full days with us. Typically, Tuesdays Wednesdays and Thursdays are our busiest days. We usually do between 15 to 40 procedures per day using all modalities, including ultrasound-guidance and assistance, stimulating catheters, Loss or resistance and everything in-between – whatever is in the best interest of the patients. After placing a block, we take ownership of them and make rounds on an average of 30 to 40 patients on the floor and follow up to 15 patients a day with ambulatory continuous peripheral nerve blocks. Our emphasis is strongly on continuous paravertebral and perineural blocks and opioid-sparing postoperative pain management. A visit to the Florida Surgical Center will offer a look at high volume ambulatory single injection and continuous ambulatory continuous blocks. We start at 0600, have 3 attendings present each day teaching 3-6 residents and Fellows at the main hospital. At FSC likewise there are 2-3 attendings every day teaching 2-3 residents and at least one fellow. Please understand this is an observational preceptorship. That said I can assure you of an experience that will stimulate your interest as well as provide direction and resources to enhance the care of your patients. The preceptorship is sponsored by equipment companies such as Teleflex. Certain HR and HIPPA requirements must be met as required by UF and Shands Hospital. These “hoops” usually take a few weeks to complete. I would suggest considering traveling on a Monday, attending on Tuesday and Wednesday and perhaps traveling back on Wednesday afternoon or after first starts and rounds on Thursday. Dates can be arranged to meet your needs. Please contact me at dbohannon@anest.ufl.edu for further information. We look forward to hearing from you. Don Bohannon
Question: I read in one of your articles that an interscalene block is contraindicated in a frozen shoulder, and that you recommend a cont. cervical PVB?
Answer: No, we don’t think ISB is absolutely contra-indicated, but we think it is relatively contra-indicated in our practice. I (APB) am also of that opinion, since of a personal series of 4700 Continuous ISB I had 14 patients who ended up with neuropathic pain (transient) and 10 of these 14 were patients who had arthroscopic capsulotomy for frozen shoulder. But, as you know, not all frozen shoulders are equal and there is MUCH more to it than that. The reason for the problem, is that the ISB is placed where the plexus crosses the first rib. This is a narrow space and, also, the plexus in the case of frozen shoulder is already under traction and stressed where it crosses the first rib because of rotation of the scapula. Since we have been doing cervical paravertebral block, this problem has not been seen – well over 2000 now for primary frozen shoulder. Secondary frozen shoulder is totally different and ISB is just fine for this. CPVB is also a better block for frozen shoulder, since it is very much motor sparing and mostly a sensory block. (Please see Pitfalls of Regional Anesthesia for shoulder surgery. Int J Shoulder Surg 2007;1: 30 – 36). The applied anatomy of the cervical paravertebral block is extensively discussed in the High-yield Block segment of this website (See here ), as is the technique of performing the block and the difference between a cervical paravertebral block and an interscalene block; two very distinctly different blocks, like an intercostal block is different from a thoracic paravertebral block and a femoral nerve block is different from a lumbar plexus block. One is a peripheral nerve block and the paravertebral block is a spinal root central nerve block. Please also see Reg Anesth Pain Med 2003: 28: 241 – 244 and Reg Anesth Pain Med 2003; 28: 406 – 413 for the original description and our experience with the first 256 CCPVB/s.
Question: I see you use continuous femoral nerve block for total knee and hip surgery. What do I tell my surgeons who object to the quadriceps weakness after such a block?
Answer: Educate them on AMI (see previous question). This has been well described since 1889 and it now seems to be become evident that blocking the afferent neural pathway of AMI will cause earlier with a longer-acting continuous femoral nerve block may even hasten recovery of the quadriceps muscles. Here is a short extract from Cam Smiths Expert Opinion piece on AMI (see below). There should be no difference in the ambulation whether a patient has a continuous nerve block or not or whether the patient is at home or not. Because of AMI, which, through the disease process and the surgery weaken the muscles in any case, the knee has to be stabilized and the quads should not be relied upon or trusted to keep a patient from falling – block or no block. We should therefore routinely place knee stabilizers on ALL our patients who underwent major hip, knee and ankle surgery such as arthroplasty. Please read up on this. The only big difference is that with a block the patient has no or very little pain and ambulation and mobilization is so much easier and PT is also pain free and much easier. Extract from Cam Smith’s Expert Opinion that will be posted in full shortly: “Arthrogenic Muscle Inhibition Another critically important topic in the understanding of orthopaedic pain and recovery from orthopaedic trauma is the concept of arthrogenic muscle inhibition, or AMI. It is reasonably well understood that joint damage, be that in the form of traumatic injury, arthritis, swelling or effusion, results in weakness in the muscle groups acting on the joint in question. Historically, much of this muscle weakness has been attributed to pain, but more recent observations have indicated very clearly that this muscle weakness persists, even in the absence of pain (Young, A. 1993. Current issues in arthrogenous inhibition. Annals of the Rheumatic Diseases 52:829-34.). This phenomenon was first described by Charcot in 1889 and originally termed “atrophic articular paralysis”, and even at that point was understood not simply to be a manifestation of pain, but represented a neurological process – a reflex arc whereby the injured joint itself was limiting activation of the muscles, which, in turn, led to muscle atrophy (Charcot J M. 1889. Clinical lectures on the diseases of the nervous system. Vol. 3. London: The New Sydenham Society, 20-31; 44-51; 52-61.). Unfortunately, Charcot’s understanding and study of this phenomenon was largely lost to history. Only much more recently has this topic begun to attract more attention. It is now understood that in the immediate aftermath of a traumatic joint injury or surgery, that muscle activation is suppressed by approximately 70%, but this immediate suppression, which most people would be able to predict, is not the end of the story. Two weeks later suppression of 30-40% is still apparent, even in the absence of ongoing pain (Stokes M, Young A. 1984. The contribution of reflex inhibition to arthrogenous muscle weakness. Clinical Science 67:7-14.; Shakespeare D T, Stokes M, Sherman K P, Young A. Reflex inhibition of the quadriceps after meniscectomy: lack of association with pain. Clinical Physiology 1985: 137-44.). This diminution of muscle activation, again in the absence of pain, can be attenuated by the application of local anesthetics (Young, A. 1993. Current issues in arthrogenous inhibition. Annals of the Rheumatic Diseases 52:829-34.; Stokes M, Young A. 1984. The contribution of reflex inhibition to arthrogenous muscle weakness. Clinical Science 67:7-14.). Suppression of muscle activation is worse in cases where joint effusions are present, and can be diminished, but not eliminated by the aspiration of the effusion. In fact, controlled studies in healthy humans have demonstrated that artificial joint effusions in the knee created by the instillation of as little as 20-30 mL in the absence of pain produce an immediate 50-60% reduction in force during both isometric and dynamic contraction (Baxendale R H, Ferrell W R, Wood L. 1985. Knee-joint distension and quadriceps maximal voluntary contraction in man [abstract]. Journal of Physiology (London) 367: 1OOP.; Young A, Stokes M, Iles J F. 1987. Effects of joint pathology on muscle. In: Duthie R B, Young A, eds. The pathophysiology of joint conttractures and their correction. Clinical Orthopaedics 219: 21-7.). Likewise, experimental knee effusions have been demonstrated to decrease activity in the spinal cord anterior horn cells and to diminish the so-called H reflex (the monosynaptic, reflexive motor response to activation of muscle spindle afferent fibres) (Iles J F, Stokes M, Young A. 1985. Reflex actions of knee-joint receptors on quadriceps in man [abstract]. Journal of Physiology (London) 360: 48P.). Studies conducted on the H reflex are of particular interest because they, unlike any of the other techniques, are pure, monosynaptic reflex arcs and do not involve any conscious or voluntary activity on the part of the participant. The most successful technique demonstrated to date to reduce AMI is the elimination of the afferent nerve input from the joint. This has been demonstrated with both the infiltration of local anesthetic to the area surrounding the joint capsule and epidural local anesthetics (Young, A. 1993. Current issues in arthrogenous inhibition. Annals of the Rheumatic Diseases 52:829-34.; Spencer J D, Hayes K C, Alexander I J. 1984. Knee joint effusion and quadriceps reflex inhibition in man. Archives of Physical Medicine and Rehabilitation 65: 171-7.; Arvidsson I, Eriksson E, Knuttson E, Arner S. 1986. Reduction of pain inhibition on voluntary muscle activation by epidural analgesia. Orthopedics 9: 1415-9.). While some authors have concluded that the recovery of muscle activation seen during epidural analgesia is simply a product of improved pain control, the discussion above demonstrates clearly that this is an oversimplification. Routine epidural anesthesia for all joint injuries and surgeries is also impractical, and may be contraindicated by concomitant coagulopathy, thrombocytopenia, or need for anticoagulation (Arvidsson I, Eriksson E, Knuttson E, Arner S. 1986. Reduction of pain inhibition on voluntary muscle activation by epidural analgesia. Orthopedics 9: 1415-9.). Fortunately, we have now arrived in the era of continuous peripheral nerve blockade. As discussed elsewhere in this chapter, in the hands of appropriately-trained anesthesiologists, catheters can now be placed on peripheral nerves in very specific tissue planes which will allow continuous infusion of local anesthetics onto the nerve, producing analgesia and interrupting the afferent limb of the reflex arcs responsible for AMI. These catheters can remain in place for several days, and new catheter designs may allow for catheters to remain in place for weeks. To date studies examining how catheter-based regional anesthesia may affect AMI and long-term outcomes have not been conducted”. Please see Cam Smith’ Bio here)
Question: Is there a place for a dedicated BLOCK ROOM?
Answer: We strongly believe that blocks should be done in dedicated and designated block areas except in pediatrics for example, where blocks are done under GA in OR’s Both inpatient and outpatient facilities should have dedicated block areas in close proximity to the operating suites with its own dedicated nursing staff and equipment. We regard it as very important not to do blocks in operating rooms if it can be avoided, because that puts time pressure on operators and almost guarantees block failure. We also are dead against doing blocks in non-dedicated areas like recovery rooms and little corners of the hospital. Not only is the equipment and resuscitation medication not readily available, it also causes people to not have the necessary respect for this important part of our practice. A dedicated nurse to help with nerve blocks, is, as for any other invasive procedure in any responsible facility a sine qua non. Please see the setting up of an Acute Pain Service here
Question: We have been doing thoracic paravertebral blocks for pancreas surgery and have been disappointed. Why do only very few of them control the pain?
Answer: Pain generated from the pancreas, as from other upper abdominal viscera, is communicated to the brain via the coeliac ganglion and the greater splanchnic nerve, which originates from the sympathetic chain from T5 – T9. If, by some magic the thoracic paravertebral block reaches the origins of this nerve, the thoracic paravertebral block will block the pain signals from the pancreas. That means the LA drug has to reach the lateral parts of the bodies of thoracic vertebrae numbers 5 – 9 bilaterally. This is very seldom the case and the somatic blocks of the lower thoracic spinal roots will not block the greater splanchnic nerve, which relays the sympathetic impulses. Like you, most have been disappointed in the thoracic paravertebral block unless it was done at the T5 level, and even then, it seldom reached the paravertebral sympathetic ganglia. You will find that changing back to epidural block for upper abdominal surgery where visceral pain is expected, the patients are much happier.
Question: What are your thoughts on blocks in frozen shoulders?
Answer: The primary concern in frozen shoulder surgeries lies in the fact that these surgeries are essentially capsulotomy of the gleno-humeral joint. As a result of this, the brachial plexus is at great risk for traction injury. The surgeon cuts the capsule of the shoulder joint and the block reduces the muscle tone. The brachial plexus may also be under stress from traction because the scapula is rotated with frozen shoulder. The area of maximum stress of the plexus is where it crosses the first rib. In fact, these surgeries have a very high rate of peripheral neuropathies post-operatively. It is wise then, to try to not include oneself in any unfortunate sequelae that may result, if possible. Cervical paravertebral block may be the ideal block to do for this condition, since it provides a more sensory than motor block, and the block is done more proximal and away from the area where the brachial plexus crosses the first rib. Be careful of the patient who presents for shoulder surgery, but presents with pain or paresthesia distal to the elbow. Bona fide shoulder pathology does not cause pain distal to the elbow. It is most likely caused by existing brachial plexitis. This condition is often associated with frozen shoulder and it is hugely under-recognized (see here). Furthermore, the axillary nerve is very closely situated to the joint capsule and can easily be damaged during surgery. It should not come as a surprise to anesthesiologists who is going to get the blame for the deltoid muscle paralysis that follows.
Question: What is AMI and what is the significance of it?
Answer: AMI stands for Arthrogenic Muscle Inhibition. Researchers found that if they inject 5 mL of saline into the knee joint of volunteers, the quadriceps strength immediately decreases by as much as 18%. The neural pathways of this has also been studied. And it makes sense, because if a joint is diseased or under stress, the joint would want the muscles to go a bit easy on it. See Reg Anesth Pain Med 2016; 41: 665 – 666 for more on this. Quadriceps dysfunction starts long before the surgery because of the disease process and AMI, then the surgery aggravates it and the dysfunction can last up to 18 months postoperatively. The femoral nerve block, if it does anything, may in fact actually block this AMI neural pathway and shorten the time to full muscular function. There are studies underway to examine this notion. Cam Smith MD, PhD, one of the Associate Editors (see here), prepared a very comprehensive Expert Opinion piece on this, which will be posted soon.
Question: What is your approach toward managing the pain after bilateral lung transplant?
Answer: Double lung transplant, is totally different from, say pancreas surgery. The “new” lungs are denervated and there is no visceral pain. If, for example lung decortication is performed, where there is tremendous visceral pain the approach would again be different. Another fact with lung transplant is that the lymphatic drainage from the transplanted lungs are also cut, so the only way that excess fluid can leave the lungs is via the venous system. The patients are therefore kept very “dry” on purpose, to prevent pulmonary edema. Finally, most of these patients had pulmonary hypertension for a long time, which took its toll on the heart and especially the right ventricle. Epidural block would for this reason initially not work, because the patients are kept hypovolemic and hypotension would be a big problem if the sympathetics are blocked. Inotropes and pressors are also undesirable because of the already stressed out heart. The ideal analgesic regimen for double lung transplant would thus be opioid-free so that respiration is not depressed, a block that does not influence the sympathetics and a pure somatic block. The incision is the so-called “clam shell” incision at the 4th to 5th interspace, and four chest drains at the T9/10 levels are placed – 2 per side, one to drain the apical areas and one to drain the basal areas. The ideal block for this is paravertebral blocks, but this means 4 thoracic paravertebral blocks; one on each side for the T4 dermatomes bilateral and one on each side for the T9/10 dermatomes. This would mean a relatively high infusion volume of LA agent, not to mention the work and effort to place 4 continuous paravertebral blocks. We have been stunned at how well the patients do with no pain and very easy coughing and mobilization with these four paravertebral blocks. We would typically run the top 2 at 5 mL per hour of 0.2% ropivacaine and the bottom two at zero infusion rate and only 5 mL patient-generated boluses if required, with ay 60-minute lockout. This gives a maximum of 960 mg per 24 hours of ropivacaine, which we feel is very safe, because patients on average only use the bottom boluses every 3 hours. Of course, a single epidural block would be much easier to place and to manage, but the hypotension in these deliberately hypovolemic patients is prohibitive. We place the blocks directly after the bronchoscopy and extubation by the transplant team (See here Library of Proposed Best Practices>.
Question: What type of block do you use for hip surgery?
Answer: There may be a marked difference between primary hip arthroplasty and revision hip arthroplasty. During primary hip surgery, the joint and sometimes the joint capsule is removed. The removal of the joint capsule may in fact denervate the hip. There is then remarkably little postoperative pain following primary hip surgery. This is not always the case with revision hip replacement. There are vast differences in the surgical approaches to the hip joint – anterior, antero-lateral, postero-lateral, posterior, etc., and we strongly advise you not to take a one-size-fits-all approach to THA. We advise you to have an in-depth discussion with your surgeon about the specific approach he or she has. We sometimes do L1/2 epidurals with 4 mL an hour ropivacaine 0.2% after a bolus for the sole anesthesia for surgery. Spinal anesthesia is in most institutions the preferred surgical anesthesia, but this is not always possible. Then, second choice would be TIVA, and 3rd choice ETGA. We sometimes do Lumbo-sacral trunk block and spinal anesthesia for the surgery, and sometimes continuous femoral nerve block tunneled medially toward the umbilicus with an added ultrasound-guided PECAN block, or we ask the surgeon to inject plain 0.5% ropivacaine into the posterior capsule. This, with a spinal or TIVA, would give you excellent results for by far the majority of THA’s. All these approaches have proponents and opponents, but basically as not all THA surgeries are created equally, all surgeons are not created equal, and the approach you choose not only has to take this into effect, but also your own skill set. The technique also depends on what anticoagulation prophylaxis is used and what the discharge plan is for the patients. For primary THA in otherwise healthy patients our preference is ambulatory (home-going) continuous femoral nerve block (See here) combined with singe-injection ultrasound-guided PECAN (See here)or posterior capsule infiltration by the surgeon with spinal or TIVA anesthesia. For revision THA on anticoagulants that preclude lumbar epidural, we would prefer continuous lumbar plexus block (L4) or Lumbosacral trunk block (L5). But, if epidural is permissible, that is also a good choice. Most high-volume knee and hip surgeons nowadays use aspirin as DVT prophylaxis in low risk patients. Please study the innervation of the hip joint here). We do not use Liposomal bupivacaine. Please see Expert Opinion here).
Question: Which catheter combination or nerve block do you use for a knee scope?
Answer: There is an age-old saying that the lower the indications, “the higher the complications”. For knee arthroscopy, we would certainly not do a continuous nerve block. In 99% of cases we would not even do a single-injection block. Having said that, the knee receives most of its anterior innervation from the femoral nerve (Please see innervation of the knee joint here). The femoral nerve innervates most of the femur and the medial side of the tibia, while the lateral part of the tibia is innervated by the sciatic nerve. It also has contributions medially and posteriorly from the obturator nerve, and posteriorly also from the sciatic nerve and in some cases laterally from the lateral cutaneous nerve of the thigh. If the proposed surgery is only a diagnostic knee arthroscopy, single injection femoral nerve block will likely be adequate, but the portal sites will most probably require infiltration. We highly recommend that you do this block postoperatively only when the patients need it. However, in the case of ligament or meniscus surgery, the contributions of the other nerves must be considered. In the case of ligament repair surgery, it is important to note that the ligament harvest site is often painful. We have had good success with sciatic nerve blocks, usually carried out from a subgluteal approach, in these cases. Please study the innervation of the knee joint here.
ANATOMY
Question: Following the logic of Hilton’s Law of Anatomy, continuous femoral nerve block alone should not work for hip and knee replacement surgery. How do you get around this?
Answer: You are absolutely right. We cover the posterior parts of the knee joint with an IPACK block and of the hip with a PECAN block (see here) or we ask the surgeon to inject 20 mL of 0.2% or 0.5% plain bupivacaine or ropivacaine into the posterior capsule during surgery. Because of the dreaded “foot drop post-surgery, surgeons are not in favor of sciatic nerve blocks, and with properly placed IPACK or PECAN blocks, sciatic nerve block, although very effective for pain, is not necessary. We do find that the posterior pain is short-lived and most patients are happy with this approach. If really necessary and after the surgeon had evaluated the common peroneal nerve function post-operatively, we sometimes – very seldom, do a subgluteal (TKA) or parasacral (THA) low-volume (2 – 10 mL), low-concentration (0.2% ropivacaine) sciatic nerve block.
Question: Please explain the difference between Perineurium, Endoneurium, Epineurium, Circimneurium, Paraneurium and Epimysium. These terms are TOTALLY confusing to me?
Answer: Thank you for this question. This is a very common question, and it is best explained by studying the Microanatomy of peripheral and central nerves here . There are also sections that explain it in detail in these texts Should you, after studying these resources, still have any questions, please send your questions to FAQ@RAEducation.com .
Question: What, in your opinion, is the most fundamental principles or successful Regional Anesthesia?
Answer: Hiltons Law of Anatomy. Please read all about this and the other very essential anatomical principles here. As Regional Anesthesia in modern times is the study of Macro- (see here and here) and sonoanatomy (see here), Acute and Peri-operative pain Medicine and continuous peripheral nerve blocks that work without secondary block failure, is the study of microanatomy (see here. If we fail to understand the circumneurium, we will not consistently be successful with CPNB’s. Please see the difference between Topical, Local and Regional Anesthesia and Acute Pain Medicine and CPNB’s here
Question: There is a difference between surgical anatomy and anatomy for RA. Why is this so and how can I learn about it?
Answer: This is a great observation, and YES, there is a big difference. Surgical anatomy has always, over centuries, been presented by beautiful photographs and drawings of dissections, to teach surgeons the basics of anatomy. To make the photographs and drawings beautiful, they had to remove the fascia (epimysium of the nerves) and other connective tissue. Surgeons, when they do their beautiful surgical dissections also do this. BUT, anatomy for regional anesthesia is totally different. Anatomy for RA depends on the understanding of these fascia and connective tissue barriers. Local anesthetic agents are useful for the very reason that they do not readily cross anatomical barriers. If this were not the case, they would be highly toxic as they would cross barriers into brain tissue (the BBB), heart tissue, etc., to name but a few. If we therefore, do not understand these tissue barriers, we have no hope of understanding regional anesthesia. That is why there is such a difference. To answer your second question, because this is so, and because this is so poorly understood and we for years studied our anatomy from surgical anatomy texts, my colleagues and I have produced “The Anatomical Foundations of Regional Anatomy and Acute Pain Medicine: Macro- Micro-, Sono- and Functional Anatomy”
Question: Where can I learn enough about sonoanatomy to be proficient with ultrasound-guided and –assisted Regional Anesthesia and Acute Pain Medicine, and why should I use anything but ultrasound?
Answer: You came to the right place. Look no further (see here). There are also a few selected LINKS in the Literature section to websites that are really good with this. For MSK ultrasound we suggest that you visit (but only if you promise to come back to RAEducation.com) see here, and here. All the ultrasound-guided and ultrasound-assisted blocks are described on RAEducation.com website see here. Single-injection nerve blocks are nowadays almost exclusively done with ultrasound, while continuous nerve blocks used for acute pain medicine is almost exclusively done with nerve stimulation applied to the catheter in our practice. Other techniques like loss of resistance to air, saline, D5W, and even electrical current as well as wave form analysis are also used for some continuous blocks such as epidurals. We believe we should all the tools available to us and not rigidly be fixated on one technique. We have to adapt to the patients’ needs and not adapt the patients to our inadequacies. To study the difference between Topical, Local and Regional Anesthesia and Acute Pain Medicine and CPNB’s here
Question: Why don’t you use the beautiful images of the Pernkopf Atlas of Anatomy on the website?
Answer: Although we agree with you that these are beautiful paintings of beautiful dissection, there exists huge controversy about the Pernkopf dissections. Especially in the communities of our Jewish colleagues there are understandable sensitivities regarding this work, and, because there are other similarly beautiful and useful sources, we elected to not include these drawings. Please read about the controversy here
Question: Why, in the era of ultrasound, should I even care about Functional Anatomy and the twitches I get with nerve stimulation?
Answer: Thank you for this interesting and common question. The reason is simple, tongue in cheek, the ultrasound picture does not yet come with labels to the structures. You might argue, so what, I can see the femoral nerve and that is enough. Not so fast. This might not need it for single-injection blocks, because the volume and concentration that you inject is high enough to respect Fick’s second Law of Diffusion, but it is going to let you down with continuous nerve blocks. With continuous nerve blocks the catheter HAS to be deep to the circumneurium (see here), because the concentration of the drug and the volume is too small to have a sufficient concentration gradient to diffuse to the axons, the volume may be taken away by the blood and lymphatic flow too quickly and P, the diffusion constant of the membrane it has to diffuse through, in this case the circumneurium, is too high. Bottom line is, the local anesthetic agent does not get to the axons and the secondary block fails. The only way, at this stage before high definition ultrasound is readily available, to identify this membrane, is to put a nerve stimulator to the catheter. Once high-definition ultrasound is more available, or the work done with machine learning is completed that labels what we see, stimulating catheters are going to be with us if we need to have a successful Acute Pain Service and especially an ambulatory acute pain service with patients going home with CPNB’s. Another issue is the correct nerve. For example, putting a catheter on the nerve to Sartorius will be totally useless for knee pain after TKA for example, and ultrasound cannot differentiate between the nerve to Sartorius and the other 6 branches of the femoral nerve. Single-injection nerve blocks are nowadays almost exclusively done with ultrasound, while continuous nerve blocks used for acute pain medicine is almost exclusively done with nerve stimulation applied to the catheter in our practice. Other techniques like loss of resistance to air, saline, D5W, and even electrical current as well as wave form analysis are also used for some continuous blocks such as epidurals. We believe we should all the tools available to us and not rigidly be fixated on one technique. We have to adapt to the patients’ needs and not adapt the patients to our inadequacies. To study the difference between Topical, Local and Regional Anesthesia and Acute Pain Medicine and CPNB’s here
ANATOMY
Question: Following the logic of Hilton’s Law of Anatomy, continuous femoral nerve block alone should not work for hip and knee replacement surgery. How do you get around this?
Answer: You are absolutely right. We cover the posterior parts of the knee joint with an IPACK block and of the hip with a PECAN block (see here) or we ask the surgeon to inject 20 mL of 0.2% or 0.5% plain bupivacaine or ropivacaine into the posterior capsule during surgery. Because of the dreaded “foot drop post-surgery, surgeons are not in favor of sciatic nerve blocks, and with properly placed IPACK or PECAN blocks, sciatic nerve block, although very effective for pain, is not necessary. We do find that the posterior pain is short-lived and most patients are happy with this approach. If really necessary and after the surgeon had evaluated the common peroneal nerve function post-operatively, we sometimes – very seldom, do a subgluteal (TKA) or parasacral (THA) low-volume (2 – 10 mL), low-concentration (0.2% ropivacaine) sciatic nerve block.
Question: Please explain the difference between Perineurium, Endoneurium, Epineurium, Circimneurium, Paraneurium and Epimysium. These terms are TOTALLY confusing to me?
Answer: Thank you for this question. This is a very common question, and it is best explained by studying the Microanatomy of peripheral and central nerves here . There are also sections that explain it in detail in these texts Should you, after studying these resources, still have any questions, please send your questions to FAQ@RAEducation.com .
Question: What, in your opinion, is the most fundamental principles or successful Regional Anesthesia?
Answer: Hiltons Law of Anatomy. Please read all about this and the other very essential anatomical principles here. As Regional Anesthesia in modern times is the study of Macro- (see here and here) and sonoanatomy (see here), Acute and Peri-operative pain Medicine and continuous peripheral nerve blocks that work without secondary block failure, is the study of microanatomy (see here. If we fail to understand the circumneurium, we will not consistently be successful with CPNB’s. Please see the difference between Topical, Local and Regional Anesthesia and Acute Pain Medicine and CPNB’s here
Question: There is a difference between surgical anatomy and anatomy for RA. Why is this so and how can I learn about it?
Answer: This is a great observation, and YES, there is a big difference. Surgical anatomy has always, over centuries, been presented by beautiful photographs and drawings of dissections, to teach surgeons the basics of anatomy. To make the photographs and drawings beautiful, they had to remove the fascia (epimysium of the nerves) and other connective tissue. Surgeons, when they do their beautiful surgical dissections also do this. BUT, anatomy for regional anesthesia is totally different. Anatomy for RA depends on the understanding of these fascia and connective tissue barriers. Local anesthetic agents are useful for the very reason that they do not readily cross anatomical barriers. If this were not the case, they would be highly toxic as they would cross barriers into brain tissue (the BBB), heart tissue, etc., to name but a few. If we therefore, do not understand these tissue barriers, we have no hope of understanding regional anesthesia. That is why there is such a difference. To answer your second question, because this is so, and because this is so poorly understood and we for years studied our anatomy from surgical anatomy texts, my colleagues and I have produced “The Anatomical Foundations of Regional Anatomy and Acute Pain Medicine: Macro- Micro-, Sono- and Functional Anatomy”
Question: Where can I learn enough about sonoanatomy to be proficient with ultrasound-guided and –assisted Regional Anesthesia and Acute Pain Medicine, and why should I use anything but ultrasound?
Answer: You came to the right place. Look no further (see here). There are also a few selected LINKS in the Literature section to websites that are really good with this. For MSK ultrasound we suggest that you visit (but only if you promise to come back to RAEducation.com) see here, and here. All the ultrasound-guided and ultrasound-assisted blocks are described on RAEducation.com website see here. Single-injection nerve blocks are nowadays almost exclusively done with ultrasound, while continuous nerve blocks used for acute pain medicine is almost exclusively done with nerve stimulation applied to the catheter in our practice. Other techniques like loss of resistance to air, saline, D5W, and even electrical current as well as wave form analysis are also used for some continuous blocks such as epidurals. We believe we should all the tools available to us and not rigidly be fixated on one technique. We have to adapt to the patients’ needs and not adapt the patients to our inadequacies. To study the difference between Topical, Local and Regional Anesthesia and Acute Pain Medicine and CPNB’s here
Question: Why don’t you use the beautiful images of the Pernkopf Atlas of Anatomy on the website?
Answer: Although we agree with you that these are beautiful paintings of beautiful dissection, there exists huge controversy about the Pernkopf dissections. Especially in the communities of our Jewish colleagues there are understandable sensitivities regarding this work, and, because there are other similarly beautiful and useful sources, we elected to not include these drawings. Please read about the controversy here
Question: Why, in the era of ultrasound, should I even care about Functional Anatomy and the twitches I get with nerve stimulation?
Answer: Thank you for this interesting and common question. The reason is simple, tongue in cheek, the ultrasound picture does not yet come with labels to the structures. You might argue, so what, I can see the femoral nerve and that is enough. Not so fast. This might not need it for single-injection blocks, because the volume and concentration that you inject is high enough to respect Fick’s second Law of Diffusion, but it is going to let you down with continuous nerve blocks. With continuous nerve blocks the catheter HAS to be deep to the circumneurium (see here), because the concentration of the drug and the volume is too small to have a sufficient concentration gradient to diffuse to the axons, the volume may be taken away by the blood and lymphatic flow too quickly and P, the diffusion constant of the membrane it has to diffuse through, in this case the circumneurium, is too high. Bottom line is, the local anesthetic agent does not get to the axons and the secondary block fails. The only way, at this stage before high definition ultrasound is readily available, to identify this membrane, is to put a nerve stimulator to the catheter. Once high-definition ultrasound is more available, or the work done with machine learning is completed that labels what we see, stimulating catheters are going to be with us if we need to have a successful Acute Pain Service and especially an ambulatory acute pain service with patients going home with CPNB’s. Another issue is the correct nerve. For example, putting a catheter on the nerve to Sartorius will be totally useless for knee pain after TKA for example, and ultrasound cannot differentiate between the nerve to Sartorius and the other 6 branches of the femoral nerve. Single-injection nerve blocks are nowadays almost exclusively done with ultrasound, while continuous nerve blocks used for acute pain medicine is almost exclusively done with nerve stimulation applied to the catheter in our practice. Other techniques like loss of resistance to air, saline, D5W, and even electrical current as well as wave form analysis are also used for some continuous blocks such as epidurals. We believe we should all the tools available to us and not rigidly be fixated on one technique. We have to adapt to the patients’ needs and not adapt the patients to our inadequacies. To study the difference between Topical, Local and Regional Anesthesia and Acute Pain Medicine and CPNB’s here
BUNDLED PAYMENT
Question: Do you have a program in place to reduce hospital stay?
Answer: We at UF have a number of programs to reduce hospital stay. For colorectal surgery, gynecology surgery and urology surgery we have an active ERAS (Early Recovery After Surgery) program. For our joint arthroplasty surgery, we have a PFCC (Patient and Family Centered Care program, and for terminal cancer patients we have a CPPC (Cancer and Palliative Care Collaboration) program. All the protocols for all these programs are posted here). Thus far we have found these programs to be very successful and we are continuously developing and tweaking them. Duis tincidunt mi at quam condimentum lobortis.
CHRONIC and CANCER PAIN BLOCKS
Question: I have had an enquiry from a pain doc at the leading London cancer hospital about the use of brachial plexus catheters for controlling cancer pain caused by malignant infiltration of the brachial plexus (lower roots) – usually secondary to metastatic breast cancer. These patients have tried all conventional analgesics but still have persistent intractable neuropathic pain. He would need to leave the catheters in place for at least a week – ideally longer. Any ideas?
Answer: There is a very easy and good solution, which is obvious to the problem. You obviously have to go proximal to the plexus infiltration, so I would like to suggest a continuous cervical paravertebral block. This can stay in for months and should give the patient complete sensory and perhaps a 10 – 20% motor block if you run 0.1 or 0.2% ropivacaine. We have left one in place for three months with excellent results. (Please see Pain Medicine 2010; 11: 1299 – 1302) .
Question: I heard via the grape vine about your cancer pain and palliative care collaboration. I work in a cancer hospital; would you mind telling me about that?
Answer by Steve Vose, MD., the director and founder of the CPPC program: Thank you for your question! You are correct; here at the University of Florida we have an initiative aimed at improving the patient’s access to the best pain management modalities possible when cancer and end-of-life diagnoses bring pain and suffering that is beyond what the primary clinician is able to comfortably treat. The UF Health Cancer and Palliative Pain Collaborative (UFH CPPC) is a multidisciplinary team made up of high-level clinicians from many different sub-specialties, all with a shared interest in treating patients with cancer and end-of-life pain complaints. Representatives from Anesthesiology (Acute and Chronic Pain), Palliative Care, Integrative Medicine, Interventional Radiology, Radiation Oncology, Neurology, Psychiatry, Pain Psychology, and our outpatient Supportive Oncology clinic together bring a wealth of experience and knowledge to this collaborative, and ensures that Cancer Pain be treated as the complex medical urgency that it is. Linked by a messaging tool within our electronic medical record system (EPIC in our case), any clinician within the UF Health system can electronically ‘present’ a patient with cancer and end-of-life pain to the CPPC and expect back within 72 hours a summary of the group’s plan of action. We ask that our members review these cases and assist in expedited scheduling for the patient. Ultimately here, time matters the most. If you are interested in speaking further about this initiative, we would love to assist. It is our sincere hope that this initiative be spread beyond UF and that the needs of this diverse patient population brought into focus nationally. (A special CANCER PAIN SECTION by Steve Vose will be coming shortly).
COMPLICATIONS
Question: What are your opinions on doing blocks asleep?
Answer: This debate originated in the previous century and is now thankfully over. We do not feel that the absence of patient discomfort (paresthesia) protects against intraneural injection of local anesthetics, and we do not even believe that intraneural injection (note not intrafascicular or intrathecal) is necessarily such a bad thing (after the work of the Bigeleisen group). The drug that is injected is usually a local anesthetic agent, which anesthetizes the nerve immediately and thus renders the intraneural injection free of pain anyway. It is certainly the case that the reports of pain on intraneural injection of contrast material from the radiology literature are true. However, when local anesthetics are injected, the sodium channels are instantly blocked. We see this every day when stimulating nerves immediately stop muscle twitching and thus motor function of the nerve with local anesthetic infusion. While we understand that the electrical property at work here is the dissipation of the current density, it is also true that the motor nerve conduction is blocked. If this is the case, and it is, the sensory component of the same nerve is also blocked. Therefore, the patient will not feel pain when injecting a local anesthetic intraneurally. This does not hold true when performing retro-bulbar blocks, however. In these cases, patients will certainly feel pain when the dura, which surrounds the optic nerve, is contacted with a needle. Therefore, the only blocks in which it is truly helpful to have the patient awake and cooperative are the very blocks that anesthesiologists routinely sedate patients heavily for, namely retro-bulbar blocks. While the preceding paragraph is true, we do practice with some medico legal pressures that are not based in science. As a result of these pressures, and the fact that most patients tolerate peripheral nerve blocks with little to no sedation, we typically place blocks in awake or lightly sedated patients, except for pediatric patients or those patients with extremely painful conditions or severe anxiety, and there is not a higher incidence of neurological complications in these patients. We do, however, fully explain the situation to the patient before we place blocks after the induction of GA. None of the arguments on both sides are convincing and we believe that it does not matter. Proper technique and proper equipment, however, matters a lot, and a moving uncooperative patient can certainly add to potential complications. Furthermore, the two things, in addition to good and solid technique that will protect one from intraneural injection (meaning intra-fascicular injection, are proper technique and high pressure (resistance) in the syringe. On the nerve root level, however, the roots are surrounded by dura and inside the dura is CSF, which has the same pressure as spinal CSF. Intra root injections therefore, does not have a high pressure and pressure monitoring devices at the root level (paravertebral and interscalene blocks) are totally useless and even dangerous. The same goes for the aspiration test. If a thin needle is placed inside the dura of a nerve root and the needle is connected to a fluid-filled syringe by a tube, aspiration will collapse the nerve tissue onto the needle tip and aspiration will be negative. Although not completely fool proof, the only ways to prevent intrathecal, or worse, intra-parenchymal injection of a nerve root, is to use a Tuohy needle, which is designed not to penetrate the dura, to open the needle to ambient pressure so that CSF can freely flow if the dura is penetrated, and to use a test dose of a low volume of lidocaine and epinephrine similar to when performing a spinal epidural block. Paravertebral blocks – all of them, cervical, thoracic, lumbar and sacral, are basically para-spinal epidural blocks, because they are performed just outside the dura, and should be revered as such.
Question: What are your thoughts on blocks for arthroscopic sub-acromial decompression?
Answer: As is the case with knee arthroscopy, this is not really painful surgery and generally does not need nerve blocks. However, there are prominent shoulder surgeons who even do not believe there is such a thing as acromial impingement, so they question the surgery. What often happens is that the surgeon does not really know what is going on inside the shoulder and a SAD is a good excuse to go and look. Because we don’t really know what they will find, we prefer to do the block after the surgery, if at all, once we know what we are treating. If, for example, the surgeon finds a rotator cuff tear and fixes it, we would place a continuous cervical paravertebral block or continuous interscalene block for the patient before we wake him or her up from the anesthesia, because we know it is going to be very painful. If, on the other hand, they don’t really find anything wrong, we would do nothing except perhaps ask the surgeons to inject a bit of LA around the port holes (never inside the joint, because bupivacaine has been proven to cause chondromalacia when injected inside the joint. If we are wrong, and it seemed like minor surgery, but the patient complains of severe pain, we can always perform a single-injection cervical paravertebral or interscalene block in the recovery room. Our indication for doing the block would then at least be sound.
Question: A number of my associates would prefer to use the continuous femoral nerve block for total knees, but are fearful of the subsequent occurrence of femoral neuropathy or femoral neuralgia. Is this concern a legitimate?
I would appreciate your thoughts on this matter. Thank you. Answer: We are big proponents of continuous femoral nerve block (CFNB) for anterior knee surgery and, in part, for major ankle surgery (For the latter it has to be done together with a continuous sciatic nerve block). The CFNB is excellent for this, the complications are almost non-existing, but the catheter has to be properly placed with a nerve stimulator to ensure sub-circumneural (sub-paraneural) catheter placement and minimal secondary block failure (see here). The old-fashioned 3-in-1 and “fascia iliaca” blocks or other “blind” catheter placement techniques are simply not good enough. We cannot afford a 70 or 80% secondary block success rate anymore. It has to be close to 100%. Approximately 20% of patients with CFNB for TKR will complain of posterior knee pain, and for this IPACK blocks have been proven to be very successful.
Question: After the work of Bigeleisen, do you still regard intraneural injection dangerous?
Answer: Depends what you mean with intraneural injection. If you mean intrafascicular, yes, it is absolutely dangerous. If it is into a central nerve such as a root or a trunk it can result in devastating complications. If, however, it is into the circumneurium (also known as Paraneurium) of peripheral nerves (see here), it is not dangerous and even desirable.
Question: Can you tell me if there is more of a chance of nerve damage to do femoral nerve blocks post total knee replacement under spinal in the recovery room?
Answer: There are only theoretical problems of nerve damage with doing blocks in the PACU after spinal, and these will always remain theoretical, since nobody will be able to do a large enough study to conclusively show a higher incidence of a complication that is so very rare. So, the practitioners must follow their own beliefs and both scenarios can easily be defended. There are some theoretical objections against doing blocks in insensitive limbs. We do not believe these are valid objections, but you will hear as many different opinions as you ask opinions. A practical problem though, is that there are bandages on the leg and patella movements are not readily visible. This can make femoral nerve block a bit more difficult, although not impossible if you understand the implantation of the Sartorius muscle is on the ASIS. Duis tincidunt mi at quam condimentum lobortis.
Question: Do you perform blocks in patients with a brachial plexitis?
Answer: Brachial plexitis manifests as pain distal to the elbow. We avoid blocks in these patients.
Question: Do you see muscular pain after your blocks?
Answer: Typically, we do not. However, many of our patients still have access to other forms of analgesia besides their peripheral nerve block, and their use likely masks any muscular pains. Interestingly though, it is this exact reason why we developed our approach to the continuous cervical paravertebral block (Reg Anesth Pain Med 2001; 26: 68; Reg Anesth Pain Med 2003; 28: 241 – 4; Reg Anesth Pain Med 2003; 28: 406 – 13) (see here). In a pilot study of 48 patients they all had posterior approaches to the roots of the brachial plexus and experienced no surgical pain, but demanded the painful catheter in their neck be removed. The extensor muscles of the neck are tender in most humans. By performing this block through the window between the levator scapula and trapezius muscles, the neck pain seen with this block has largely been eliminated.
Question: Do you see neuropathic pain after blocks?
Answer: Neuropathic pain does not play a real role in our practice. In fact, we have had some success treating chronic neuropathic pain with continuous peripheral nerve blocks. Having said that, it is important to shy away from interscalene blocks in cases where brachial plexitis may be suspected. We are very careful with patients scheduled for frozen shoulder surgery and for subacromial decompression. Also for young adult female patients scheduled for capsulorraphy. We are also much more inclined to do cervical paravertebral blocks than interscalene blocks because, if the nerves are irritated. That is usually where the nerves cross the first rib, and we shy away from that position – typically where an interscalene block ends up. We are yet to see a case of post-block neuropathic pain following cervical paravertebral block with a collective experience of about 20,000 + blocks. Traction by the surgeons on the arm and thus on the brachial plexus is the most common cause of postoperative neuropathic pain.
Question: Do you use epinephrine in your local anesthetic?
Answer: As a result of the work of Selander et al. (Acta Anaesthesiol Scand 1979 Apr, 23(2): 127-136), we believe that epinephrine is a risk factor for peripheral nerve damage due to ischemia, and avoid it in our injections and infusions. We do, however, use epinephrine as a vascular marker when necessary, for example with epidural and paravertebral blocks (para-spinal epidural blocks). Epinephrine causes nerve ischemia, and because of that, shortens the onset time of nerve blocks and causes blocks to be denser. This ischemia may also be responsible for nerve damage if combined with other factors such as nerves in confined spaces, hematoma formation, large volume local anesthetics, etc., that may add to nerve ischemia. As a basic principle, nerve ischemia is not a good thing.
Question: How do you prevent the neck pain that plagues cervical paravertebral block?
Answer: Initially, when we first designed and started using this block, we adopted the technique described by Pippa in 1990 and before him Kappis in 1912. We just placed a Tuohy needle and advanced a catheter through it. We entered 2 – 3 cm lateral of the spinous processes of the cervical vertebrae and penetrated the extensor muscles of the neck. We had good pain relief of the shoulder, but 48 of the first 50 patient complained about severe neck pain where the catheter entered. We then went to the anatomy lab and saw that there is a “window” between the levator scapulae and trapezius muscles. We modified the technique to separate these two muscles before needle placement and advanced the needle to make contact with the posterior tubercle of the transverse process of the 7th cervical vertebra. The rest, as they say, is history. This problem for the most part disappeared. Now and again we still get a patient with posterior neck pain, but we then know we inadvertently penetrated the extensor muscles of the neck. Simple NSAID’s normally solve this problem. This is not a problem with continuous interscalene block, because with this block the middle scalene is penetrated, staying well clear of the extensors of the neck, which are usually in most people a bit tense and tender to start off with (see here)
Question: What do you think is the reason why we see so much “burning arms” (transient neuropathic arm pain) after continuous interscalene block and not after continuous cervical paravertebral block?
Answer: This is a difficult question to answer, because we don’t really know why. What we do know is that since we started using the CCPVB as our go-to block instead of continuous interscalene block, this problem totally disappeared from our practice. Where our surgeons routinely prescribed gabapentin to their patients post CISB, they do not do it anymore. We can speculate that the reason is the same reason why we get permanent neuropathic pain when we cut a mixed nerve, while we do not get it when we cut a sensory nerve. With CCPVB we chemically “cut” a sensory nerve, while with CISB we chemically “cut” a mixed sensory and motor nerve. The fact that the “cut” is temporary, probably accounts for the transient nature of the neuropathic pain, but in reality, we don’t know the true reason. We only know that we don’t ever see it with CCPVB (See here).
Question: What guidelines do you follow for anticoagulation agents and neuraxial blocks?
Answer: We follow the ASRA guidelines. There is a very handy App that can be downloaded for a very nominal fee that is regularly updated by ASRA and it gives us the most up to date information. (Please see). There is also an App by ASRA for use during Chronic Pain procedures. These are most useful.
Question: Where can I read, or even better still, see how to do these blocks?
Answer: All the high-yield (and not-so high-yield blocks) can be studied here
CONTINUOUS BLOCKS
Question: What is the role of stimulating catheters in the era of ultrasound?
Answer: This is an interesting question, but not everybody agrees on the answer. There is a full text tutorial on this (see here), but in short, we cannot even begin to send patients home with continuous peripheral nerve blocks (CPNB) if the block does not work 100%. We tried that back in 1992 and 50% of patients had to be readmitted for pain management. If we place a nerve block needle with ultrasound and hydro-dissect to “open the space” we open the sub-epimyseal space. This forms the so-called “doughnut sign”. Placing a catheter into the sub-epimyseal space is an almost guarantee for secondary block failure. The primary block with a high volume and high concentration may work just fine, because the concentration gradient is high enough to reach the nerve axons where it blocks their sodium channels. With the secondary block, however, the concentration is now too low and the volume too low to have a sufficient gradient to diffuse through the circumneurium (also known as the paraneurium or “gliding apparatus” in surgical texts – see here). Anderson and Karmakar have recently demonstrated this layer and, especially the Anderson group, has shown that this circumneurium is a relatively impermeable membrane. For that reason, we HAVE to place the catheter into the sub-circumneural space (or sub-paraneural space) to have any chance of not being plagued by secondary block failure. The only way to reliably place a catheter in this sweet spot of the nerve, is by applying a nerve stimulator to the catheter. High-definition ultrasound, as introduced by Manoj Karmakar and his group from Hong-Kong, may well change this, but for now we do not have a way to place a catheter reliably and consistently into this space.
Question: Do you consider a paravertebral block the same as a neuraxial block?
Answer: After the work of the Chelly group of Pittsburg, PA, we do not follow the ASRA guidelines for anti-coagulated patients when performing paravertebral blocks anymore. While these guidelines are based on a paucity of scientific data, without that data, we have in the past chosen to err on the side of conservatism and caution, but since the data is clearer now, we believe that, within reason, the paravertebral blocks can be safely done in the presence of prophylactic anticoagulants. It is however an para-neuraxial or para-spinal epidural block, because it is done just outside the dural sleeve surrounding the spinal roots, and should be revered with the same respect as a neuraxial or spinal epidural block: large-bore Tuohy needle open to ambient pressure, test dosing with small-dose lidocaine and epinephrine to rule out intrathecal or intravascular injection, injection through the catheter only, etc.
Question: How do you do a lumbosacral lumbar paravertebral block? What are the landmarks and how do you differentiate?
Answer: The two blocks are identical. The only difference is that with the lumbosacral trunk paravertebral block we walk off cephalad of the transverse process of L5 (Kiki’s point) and get a quadriceps and hamstring twitch, while with lumbar plexus block we walk off cephalad off of the L3 or L4 transverse process and only get a quadriceps twitch. Please see the technique under the High-yield blocks heading here.
Question: How exactly do you do a cervical paravertebral block?
Answer: Under the heading of High Yield blocks on this website you will find details of applied macro and microanatomy for the CCPVB and the technique (see here). There is also a Kindle and Hard copy book that describes this block in much detai. (see hereand here Amazon.com > Books > Boezaart
Question: How exactly do you do a continuous proximal infraclavicular block?
Answer: Originally this block was described without ultrasound and with nerve stimulation only. A complete description of the nerve stimulator-assisted proximal infraclavicular block (although it was not named as such but only as the continuous infraclavicular block) can be found on pages 81 – 85 of “The Atlas of Peripheral Nerve Blocks and Anatomy for Orthopaedic Anesthesia” here It is available in a number of different languages, and also here). The video can also be seen under the heading of Pre-ultrasound blocks elsewhere on the RAEducation.com website. (If it is not yet posted it will be soon). This is a very safe and easy approach that works just great if ultrasound is not available. With ultrasound, however, the probe is walked off the clavicle and the axillary artery and vein identified. The catheter is placed in the circumneurium that surrounds all three the cords in the proximal infraclavicular area (see here). Sala-Blanch and colleagues recently described this anatomy very elegantly (Sala-Blanch X, Reina MA, Pangthipampai P, Karmakar MK. Anatomic basis for brachial plexus block at the costoclavicular space: a cadaver anatomic study. Reg Anesth Pain Med. 2016; 41: 387–391).
Question: Do you perform blocks in patients with a brachial plexitis?
Answer: Brachial plexitis manifests as pain distal to the elbow. We avoid blocks in these patients.
Question: I have just finished watching the cervical paravertebral workshop movie on the old RASCI CD. (I believe it is the second edition CD.) During the narration, lidocaine with epinephrine is discussed as one drug that may be used with this brachial plexus catheter technique. I thought the teaching was not to use epinephrine ever when placing a peripheral nerve catheter. Please clarify this for me.
Answer: You sure paid attention. The lidocaine with epinephrine is for the skin and subcutaneous numbing and not for the block. This is simply to reduce bleeding from the needle puncture etc. We do not use epinephrine for blocks. The simple reason is that it does nothing for the block. If anything, there is a possibility of nerve ischemia and if there are other factors present that will also cause nerve ischemia, like nerves in confined spaces, volume, traction on nerves during shoulder surgery, hematomas, etc., this will not make the nerve any better. If anything, epinephrine will make the block last longer, and it can make the block denser (both due to ischemia), which we don’t really want in any case. The test dose that we use with lidocaine and epinephrine is for a test dose the same as we use for epidural block. Remember that all paravertebral blocks are done on nerve roots that are surrounded by dura. They are therefore para-spinal epidural blocks and we regard them the same as spinal epidural blocks. The epinephrine is to test for intravascular injection and the lidocaine for intrathecal injection.
Question: Is there any place in your practice for adding drugs in your LA to make single-shot blocks last longer?
Answer: Short answer: No. Please see Reg Anesth Pain Med 2015; 16: 13 – 17. If we need a long-acting block, we place a catheter for a continuous nerve block over which we have full control.
Question: Is there still a place for eye blocks in modern ophthalmology?
Answer: Professor Aziz Ezzat, one of our Editorial Board members addressed this question in a future EXPERT OPINION for us on this website (Coming soon). If his full opinion is not yet available, we will post it shortly. In short, he opined that for the success of phacoemulsification under topical anesthesia, you need to have an experienced surgeon doing uncomplicated surgery on a cooperative patient. This triad is present on odd occasions, and very frequently does not happen. The experienced surgeon will take the advantage of the eye movement to his advantage, but a less experienced or real high-volume surgeon would prefer to perform the surgery on akinetic eyes. Please see for an editorial written by Professor Ezzat: “The role of the anaesthetist in ophthalmology in the 21st century”.
Question: Tell me the difference between a lumbar plexus block and a psoas compartment block?
Answer: The psoas compartment block is kind of old fashioned and based on “filling” the compartment with a high volume of local anesthetic agent and hope that we get to the nerves as well. We would place a loss of resistance syringe on the Tuohy needle and, upon entry into the psoas compartment, which is a very vascular compartment filled with a loosely packed muscle, we place a catheter in this compartment. With the lumbar plexus or lumbar paravertebral block, we do the same, but we also put a nerve stimulator on the needle and advance the needle until we encounter the lumbar plexus, which gives us quadriceps muscle twitches. We then put a nerve stimulator on the catheter and place the catheter in the sub-circumneural space of the nerve root. We can now use a very small volume of local anesthetic agent. If we place the needle and catheter onto the lumbosacral root we get a quadriceps and hamstring twitch and a lumbar a sacral plexus block. The up side of this is that the pain from the hip and knee, for example, are very well controlled. The down side, however, is that both quadriceps and hamstring weakness may make it difficult to mobilize the patient. Note, if we enter “Kiki’s Space, just above the transverse space of the 5th lumbar vertebra, we consistently get a quadriceps and hamstring twitch as we approach the Lumbosacral trunk. (See “The Lumbar Plexus” here)
Question: What are your thoughts on glue to keep the catheter in place?
Answer: It is not necessary if tunneling is used, but it may be of value. Since we tunnel all our catheters, we have very little experience with this. It is expensive and doesn’t really add any value.
Question: Where can I read, or even better still, see how to do these blocks?
Answer: All the high-yield (and not-so high-yield blocks) can be studied here
Question: What corrections do you make with the needle and catheter when performing an infraclavicular block?
Answer: Corrections, or redirections, are an essential component of successful continuous peripheral nerve block placement. In fact, redirections are needed to prevent secondary block failure with or without ultrasound guidance. If the catheter is advanced in the sub-epimyseal space, the primary block will work just fine, but the next day, when a low concentration and volume are used, the diffusion to the axons cannot take place. For that reason, we strongly advise the use of the so-called “dual technique” where the needle is placed with ultrasound-guidance, and the catheter is placed with nerve stimulation. If the twitches continue during catheter advancement, it simply means the catheter is deep to the circumneurium and the secondary block will not fail. If the twitches disappear, it means the catheter is in the sub-epimyseal space and the secondary block will most likely fail. Please study the microanatomy of the peripheral nerves here. In the case of an infraclavicular block, knowledge of the relationship of the brachial plexus cords is essential. Please study this anatomy here. For a continuous infraclavicular block we highly recommend the proximal (or costo-clavicular) approach (see here), because the three cords are all bundled together by the same circumneurium. More distal these cords split away and a continuous block would violate Hilton’s Law of Anatomy. See anatomical principles here. It is, however, very important to fully understand the circumneurium (previously known as the paraneurium) and its relationship to the cords of the brachial plexus. Please see here for more on this.
Question: What do you do if you have a negative Raj test?
Answer: The Raj test indicates that at the moment the first µL of local anesthetic (or other conductive solution) exits the catheter or needle, the current density is being dissipated from its tip and the motor response stops. This may indicate that the tip was indeed in the cub-circumneural space of the nerve at the time of injection, which is the “sweet spot” of the nerve. This still needs to be proven by formal research, but virtually guarantees a successful secondary block with continuous nerve blocks. What to do if the test is negative is still an open question, but certainly intravascular catheter or needle placement would cause a negative Raj test, in which case the catheter needs to be replaced. This test was initially proposed by Raj as a means to ensure needle tip proximity to nerves with uninsulated needles. When using uninsulated needles, it is possible to have the needle tip several cm away from the nerve, yet still stimulate the nerve through the side of the needle. This test thus became important to establish whether or not the needle tip, and subsequently the local anesthetic, was near the nerve. Since we now understand the microanatomy of the nerves better, this original explanation does not hold water anymore.
Question: What do you mean by High-Yield Blocks?
Answer: In short, a high-yield block is one that gives you maximum bang for your buck. It is a block that always works and has no unwanted side effects and failures. Obviously that kind of block does not exist, but we are working toward such a Utopia. If one very critically evaluate blocks today, there is a world of weird and wonderful blocks out there, but for most of these, the approach has been to invent a block, and then find a job for it. It should be the other way around. We should have a clinical need and then design a block to address this need or problem. There are basically 12 or so blocks that fall into this category (see here). For continuous blocks, they are continuous cervical paravertebral, proximal infraclavicular, thoracic and lumbar paravertebral, femoral and subgluteal sciatic nerve blocks as well as lumbar and thoracic epidurals. For single-injection blocks these include cervical paravertebral (or interscalene (see here), supraclavicular, femoral, sciatic parasacral with ultrasound, subgluteal and popliteal ankle block and spinal block. With these blocks, a modern Acute Pain Service (see here) can very effectively be managed. We strongly advise division chiefs to focus on doing the high-yield blocks (see here) really well and then do the other blocks (see here when indicated.
Question: What is the direction of the needle when performing a lumbar paravertebral block?
Answer: When performing any paravertebral block; cervical, thoracic, or lumbar, (see here), we direct the catheter away from midline. The bevel of the needle therefore faces away from the midline to prevent epidural placement of the catheter. (See Lucas SD, Higdon T, et al. Pain Medicine 2011; 12: 1284 – 1289).
Question: What is the loss of resistance in a cervical paravertebral actually caused by?
Answer: The loss of resistance in the CCPVB is found as the needle exits the posterior scalene muscle slips of origin as they attach to the posterior tubercle of the transverse processes of the lower three cervical vertebrae (see here) . The posterior scalene muscle at this level is a tendon and LORA is very clear as you exit this muscle. As is true for all paravertebral blocks – cervical, thoracic or lumbar, we walk off a bony structure (the transverse processes in all instances) and then penetrate a dense tissue (the posterior scalene muscle slips of origin in case of the CCPVB, the costotransverse ligament in the thoracic region, and the posterior fascia of the quadratus lumborum muscle in the lumbar region. Immediately after we walk off this bony structure we encounter the C6 nerve root in the neck, the thoracic spinal root of the lumbar or lumbosacral plexus). For the posterior approach interscalene block, however, the needle goes through the middle scalene muscle, which is fleshy and does not provide a clear loss of resistance to air. The upper trunk and not the C6 root is encountered in the case of interscalene block.
Question: What is the loss of resistance in a cervical paravertebral actually caused by?
Question: What is the origin of the Continuous Infraclavicular Block? Answer: I (André Boezaart) do claim some involvement with this. Way back in 1975 during Operation Savannah, which was part of the Secret War in Angola (see here), I was conscripted and deployed as anesthesiologist for No 1 Forward Surgical Unit that moved North with the front. Some of our soldiers got severe hand injuries from the back-blast of an unknown to them captured USSR cannon and we had to do daily debridement and dressing changes for them. At the time, our equipment was very primitive and limited in comparison to today’s standards and I did daily axillary nerve blocks on the patients. To save manpower, I then did a 1 cm cut-down under local anesthetic to identify the brachial artery and then fed a central line catheter right next to the artery cephalad until it would no longer go. We then put a stitch in the small wound and every day just injected 20 mL of bupivacaine 0.5% through the catheter. We left the catheters in for 3 – 4 weeks and sent the patients back “home” with 10 syringes filled with 10 mL of 0.5% bupivacaine with instructions that if they have pain, they can just ask their buddies to inject 5 or 10 mL through the catheter. This worked remarkably well, and only much later, toward the end of the century, after we had been disappointed with the continuous distal infraclavicular blocks, did it dawn upon us that we have to block ALL three the cords with the continuous infusion to have analgesia for major hand, wrist and elbow surgery. We then adapted the axillary rout to going directly proximal infraclavicular and placing a stimulating catheter. It is now again our go-to technique after almost a half a century (see pages 81 – 85 of “The Atlas of Peripheral Nerve Blocks and Anatomy for Orthopaedic Anesthesia” here It is available in a number of different languages, and also here). .
Question: What is the loss of resistance in a cervical paravertebral actually caused by?
Question: What is the role of the skin bridge? Answer: The skin bridge acts as an anchor for the catheter and facilitates easy catheter removal. While securing the proximal end of the catheter, the distal end of the catheter is removed from the patient by lifting up on the skin bridge. Once the distal end is free from the patient, the catheter can be easily pulled free from the patient from its proximal end. With a skin-bridge, catheter removal is easier, but there is a higher incidence of leaking around the catheter entry site. If the catheter is tunneled without a skin-bridge, its removal may be more difficult, but leakage (and probably infection) will be less of a problem (see here see pages 149 – 155 of “The Atlas of Peripheral Nerve Blocks and Anatomy for Orthopaedic Anesthesia” here ).
Question: Which way do you thread the catheter for a continuous femoral block?
Answer: We thread femoral catheters proximally, toward the lumbar plexus. In fact, it is not uncommon to be able to stimulate (and subsequently provide analgesia to) the obturator nerve from the femoral approach. We do, however, recommend advancing the catheter only 3-5 cm beyond the needle tip for all blocks. The femoral nerve splits into its seven branches distally and distal threading will cause the catheter to settle on one of these peripheral nerves. Please see Continuous Femoral Nerve Block in the High-yield blocks section here. Please also study the macro-, sono-, and micro-anatomy of the femoral nerve here.
Question: Which way do you thread the catheter for a continuous sciatic nerve block?
Answer: All nerves start off from many roots or trunks, then combine as one nerve and then finally split into many branches. The sciatic nerve is no exception. It starts off as the sciatic plexus, becomes the femoral nerve and then splits again in the popliteal area into its terminal branches; the tibial and common peroneal nerves. You want the catheter for a continuous nerve block to be on the main nerve and not on one of the roots or trunks or on one of the terminal branches. We therefore thread sciatic catheters caudally or proximally depending on the approach. If a subgluteal approach is used, the catheter is threaded distally, but if a popliteal approach is used the catheter is threaded proximally. Please see Continuous Sciatic Nerve Block in the High-yield blocks section here. Please also study the macro-, sono-, and micro-anatomy of the sciatic nerve here.
Question: Why would you do a lumbosacral lumbar paravertebral block vs. a lumbar plexus block?
Answer: A lumbosacral paravertebral block would block the lumbar and the sacral plexus (the femoral, lateral cutaneous nerve of the thigh, the obturator nerve and the sciatic nerve, while the lumbar plexus block will not block the sciatic nerve. As said in the previous question, the up side of this is that the pain from the hip and knee, for example, are very well controlled with lumbosacral paravertebral block. The down side, however, is that both quadriceps and hamstring weakness may make it difficult to mobilize the patient. (See “The Lumbar Plexus” here)
Question: Why would you use a paravertebral block over an epidural block?
Answer: Paravertebral block allows for unilateral analgesia without the hemodynamic and visceral side effects of epidural anesthesia. It has no effect on visceral (sympathetic mediated) pain and should therefore not be used when visceral pain is present such as during major laparotomy, where visceral pleura is involved, if blood-flow to the gut and gut function is important, etc. It is very important to realize that paravertebral blocks like thoracic or lumbar paravertebral blocks, block only the somatic pain from the chest and abdominal walls only. If visceral pain is also present, such as in the case of pancreatitis, lung surgery, etc., where the viscera is not removed, paravertebral block is useless unless it somehow blocks the greater splanchnic nerve in the case of the pancreas and the thoracic paravertebral sympathetic chain in the case of the lung. If the viscera had been removed, such as the case may be with hysterectomy and cholecystectomy for example, or if the viscera had been denervated, as is the case with lung transplant, paravertebral block will be just fine. The quagmire of course is that the visceral pain reaches the brain via the sympathetic nerves and these have to be blocked to manage visceral pain. This also, in the often presence of hypovolemia, results in hypotension because the sympathetics have been blocked and the body cannot respond to the hypovolemia or other causes of hypotension. The greater splanchnic nerve comes off T5 – T9 and originates from the coeliac plexus, and if that is not blocked with the paravertebral block, the patient will suffer severe visceral pain. Therefore, if visceral pain is present, epidural block is indicated and NOT paravertebral block.
CPNB AT HOME
Question: Do you send patients home after major hip and knee surgery with blocks? What blocks?
Answer: For hip and knee surgery we send patients home with blocks and we ask the Home Nursing and PT/OT care to visit them daily. We do continuous femoral nerve blocks and tunnel them medially for hips to the abdominal wall and lateral for knees (see here). For the posterior pain, we do IPACK blocks for knees PECAN blocks for hips. This seems to work well, but all the patients use walkers for the first 10 or so days and hip and knee surgery patients use knee braces routinely if they have to ambulate until the PT/OT says it’s OK to walk without it (see here Library of Proposed Best Practices ) .
Question: Is there anywhere that patients can read about regional anesthesia?
Answer: We have produced a booklet “Understanding Nerve blocks” (see here) . This has all the blocks, for what surgery and what to be careful of. You can get it in Kindle or printed format. This booklet is especially valuable for nurses, physical therapists and other non-anesthesiology or non-surgery professionals. Please also refer your patients to .here.This section is free access for patients and does not require membership.
Question: Who follows the patients with continuous blocks at home?
Answer: We started off with shoulder patients to follow them ourselves by phoning them daily, but we have now moved to Home Care Nurses and PT’s to visit the patients daily (see here Library of Proposed Best Practices>)
EARLY RECOVERY AFTER SURGERY (ERAS)
Question: How have you adapted the ERAS (Early Recovery After Surgery) for your practice?
Answer: Please see our protocols for this and our PFCC (patient and family centered care) programs here). .
Question: What would you advise as a solid protocol for ERAS after cole-rectal surgery?
Answer: Thanks for this question. Every institution and practice is obviously different because their surgeon and patient population are different, which pose different demands. In a very busy practice where the hospital stay had been halved for cole-rectal surgery and patient satisfaction doubled, we suggest that you study and adapt the protocols in our Library of Proposed Best Practices that have stood the test of time. Please look through these here. You will find some protocols on ERAS, double lung transplants, Chest trauma, Total joint replacement and many others here. It is, however, imperative that our continuous blocks and epidurals work, without any secondary block failure and that we have a mature Acute Pain Service and immaculate cooperation between surgeons, anesthesiologists, acute pain specialists, physical and occupational therapists, nursing services, home-cares nurses and administrators. This cooperation is not going to come without considerable effort. We suggest that you follow the lead of the PFCC group described here.
Question: Why do you do epidurals for laparoscopic colectomies?
Answer: This is an interesting and important question. Intuitively if the viscera are removed by the surgery and the surgery is laparoscopic, the patients should not really have much pain – certainly not enough to warrant an epidural. When a patient undergoes surgery, or finds him or herself in another stress situation, the autonomic nervous system shuts off the blood flow to the gut and decreases the gut motility. We do not need our gut to run away. Blocking the sympathetics to the gut, would therefore improve the gut blood flow and healing and prevent ilius. We find that we can feed the patients on day one and the GIT starts working within 12 hours with an epidural in place, as opposed to 3 – 4 days without an epidural and especially if opioids are used. We totally avoid the use of opioids in these patients (see ERAS protocol here).
GENERAL
Question: Why do you spend so much time and energy on RAEducation.com? Is there not enough junk out there on the internet already?
Answer: I take it you are kidding. It is because there is so much junk out there on the internet and elsewhere that we are spending all this time and energy on RAEducation.com. If you look at our panel of expert consultants (see here) you will see that they come from all over the world, from every continent and not one of them is not a renowned and acknowledged world expert in his or her field of expertise. We all share a passion for RA and APM and feel that the folks out there in the field, and most importantly, our patients, deserve the unfiltered truth as we currently understand it in the best interest of our patients. I, as most of my colleagues on the Editorial Panel, are regularly involved as expert witnesses in medico-legal challenges and the standard of Regional Anesthesia and Acute Pain Medicine out there is sometimes not what you would desire. If we have state of the art education of physicians, nurses, other paramedics and patients, frank, polite and robust discussions and debates, we believe that the time and energy will be well-spent. Thanks for the question. Editor-in-Chief .
OUTPATIENT MAJOR JOINT SURGERY
Question: What do you teach your Home Care Nurses and Physical Therapists?
Answer: We have a very extensive program for teaching these professionals. The lecture for the nurses and PT’s will be posted under the Nurses and Patient section of the website. See here Library of Proposed Best Practices) and also here .
Question: What is the maximum length of time that you keep a catheter in place?
Answer: We typically keep them in place for 2-7 days, but have had good success for as long as 3 months. The best judge for how long a catheter should stay in, is the patient. We turn the infusion off every day on the morning rounds (or when the patient is at home by his or her caregiver) and after an hour or so ask the patient if the block is still required. If yes, we bolus the block and let it run for another 24 hours. If no, we remove the catheter. The FDA has, however, not approved the StimuCath, which we used extensively for use of longer than 72 hours. The new UltraCath should have no limitations since it is made of the same material as the FlexBlock catheter and FlexTip epidural catheters with the difference that the tip is electrically conductive and we can thus stimulate through it. .
Question: What would you advise as a solid protocol for major total joint replacement?
Answer: Thanks for this question. Every institution and practice is obviously different because their surgeon and patient population are different, which pose different demands. In a very busy >>2,000 TJR’s per year practice, where 20+% of patients are discharged on POD1 with CPNB’s and at least 60% are discharged on POD1 with CPNB’s and no or very little opioids, the protocols in our Library of Proposed Best Practices have stood the test of time. Please look through these here. You will also find some protocols on ERAS, double lung transplants, Chest trauma and many others here. It is, however, imperative that our continuous blocks work, without any secondary block failure and that we have a mature Acute Pain Service and immaculate cooperation between surgeons, anesthesiologists, acute pain specialists, physical and occupational therapists, nursing services, home-cares nurses and administrators. This cooperation is not going to come without considerable effort. We suggest that you follow the lead of the PFCC group described here. .
Question: Who removes your catheters?
Answer: Although we allow the patient to remove the catheters, we prefer to have the patients visited by a nurse practitioner at his/her home every day and this nurse removes the catheter. These Home Care Nurses are available in most counties and cities and towns in the USA, and there is really no reason not to make use of their excellent services. When the patient is in the hospital, the nurses of the Acute Pain Service remove the catheters. (Please see the Tutorial “CNPB at Home” here .
Question: Would you be kind enough to share your protocols for same-day (outpatient) major hip, knee and shoulder surgery?
Answer: Absolutely. Please see here Library of Proposed Best Practices) .
PHARMACOLOGY
Question: What is your opinion on Lipid rescue?
Answer: Please see everything you need to know about that here Also, Guy Weinberg MD, one of our Associate Editors (see here), has a very nice website that soecifically deals with Lipid Rescue. Please see www.lipidrescue.org .
PRE-ULTRASOUND BLOCKS
Question: Are twitches affected distal to your blocks?
Answer: Short answer – no. The nerves can be viewed as “electrical wires”. If it is cut proximally (blocked with a local anesthetic agent), when applying a stimulus (current) more distal, the motor response will not be influenced and will be as if not “cut” proximally. Obviously, if the nerve has been blocked distally, applying a stimulus proximal will not evoke any motor response. .
SINGLE-INJECTION BLOCKS
Question: Do you do supraclavicular blocks? If yes, why did you change your practice?
Answer: Single-injection supraclavicular block went from a no-no to our preferred single-injection block for distal lower extremity surgery since the advent of ultrasound (see here). Without ultrasound, this block had an unacceptable incidence of pneumothorax associated with it. In our practice, this has totally disappeared and the only pneumothoraxes we have seen in the past four or five years were with nerve stimulator-guided infraclavicular blocks to the best of our knowledge. .
Question: What is an IPACK block? Why would you do an IPACK block?
Answer: To address the posterior pain after total knee arthroplasty, many approaches have been tried over the years. The most successful was sciatic nerve block, but because the surgeons wanted to evaluate the common peroneal nerve function after valgus knee replacement, this was not very popular. Then an era was entered when the surgeons injected a mixture of steroids, NSAID’s, opioids and local anesthetic agents into the posterior joint capsule. That was followed by an era of injection of liposomal (encapsulated) bupivacaine into the capsule, and that era is now fast drawing to a close, because the drug (Exparel) does not seem to be everything it promised to be and is proving no better than regular garden variety bupivacaine, at 100 X the price (see here). Because we know that the posterior branch of the obturator nerve and the two distal branches of the sciatic nerve form the posterior geniculate plexus that innervate the posterior capsule, and that these nerves follow the geniculate arteries, we now, under ultrasound-guidance, do the IPACK block (see here) Infiltration between the Popliteal Artery and the Capsule of the Knee and a good description can be seen here.It holds great promise. .
Question: What pulse width do you use on your nerve stimulator?
Answer: We use 300 microseconds. It does not really matter which you use, as long as you use the same pulse width consistently, so that you get used to the quality of the motor response. The older view was that the higher the pulse width, the more painful the stimulation would be. This does not hold any truth anymore. .
ULTRASOUND
Question: What is the role of ultrasound in blocks?
Answer: Ultrasound is used for most, if not all high-yield single-injection blocks with very few exceptions. There is the added advantage of knowledge of the anatomic variations in the region of a block even before needle puncture occurs. But the deeper the nerve, the more you need it and the less it helps you. Having said that, like ultrasound has not replaced X-rays but added to the armamentarium of radiologists and orthopaedic surgeons, so does ultrasound add value to our practice of regional anesthesia. It does not replace nerve stimulation, but adds to it. We have found catheter placement into the “sweat-spot” of the nerve deep to the circumneurium (aka paraneurium) (see here) very disappointing with ultrasound alone. We rely heavily on the “dual technique” of placing the needle with ultrasound and then placing the catheter into the sub-circumneural space by applying a nerve stimulator to the catheter (see here). This technique almost eliminated the troublesome secondary block failure problem from our practice. Please see the micro-anatomy of peripheral nerves here. .
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