Continuous nerve blocks for orthopedic injuries

Continuous Nerve Blocks for Orthopedic Injuries Sugantha Ganapathy, FRCA, FRCPC

Orthopedic injuries occur as a component of multisystem injuries; however, more than 50% of them occur in isolation. The emergent surgery necessitated by such injuries and the frequent need for repeated surgery for wound management make continuous regional anesthetic techniques useful in these patients. Compared with opioids, these techniques provide improved activity-associated analgesia with minimal side effects, particularly with bone injuries. The sympathetic block that accompanies continuous catheter regional anesthetic blocks (CCBs) plays a desirable role in improving the microcirculation in the presence of vascular compromise. The disadvantages include masking of the onset of compartment syndrome and the inability to evaluate neurologic integrity in the area covered by the block. Complex regional pain syndromes after orthopedic trauma have been managed with CCBs to provide pain relief and continuous sympathetic blockade. A number of them show improvement if the intervention is made early. Further randomized studies are required to establish the role of continuous peripheral nerve blocks for complex regional pain syndromes. CCBs have been used for release of injury-related arthrosclerosis and allow the use of continuous passive motion machines to maintain the range of motion while providing excellent movement-associated analgesia. Although brachial plexus blocks cover most of the upper limb pain, lower limb injuries require blockade of lumbar plexus as well as sciatic nerve. Continuous paravertebral blocks may be used for chest injuries such as multiple rib fractures. Wound catheter infusion near the nerves may improve analgesia after amputations and may have a beneficial role in reducing phantom pain. Copyright © 2002 by W.B. Saunders Company

rthopedic trauma may occur in isolation after accidental falls in the elderly, sports-related activities, O and accidental injuries with machines such as lawnmowers and chainsaws. More than 40% of orthopedic traumas occur as a component of multiple injuries after vehicular accidents. When the injury occurs as a component of multisystem trauma, patients often have associated head, spine, abdominal, and chest injuries and are managed by a trauma triage team often with initial endotracheal intubation and a set pattern of trauma evaluation. Analgesia is From the Department of Anesthesia, University of Western Ontario, London Health Sciences Centre, University Campus, London, Ontario, Canada. Address reprint requests to Sugantha Ganapathy, FRCA, FRCPC, Department of Anesthesia, 339 Windermere Rd, London, Ontario, N6A 5A5 Canada. Copyright © 2002 by W.B. Saunders Company 1084-208X/02/0601-0003$35.00/0 doi:10.1053/trap.2002.29357

often delayed until all clinical and particularly neurologic evaluation is completed. Some of these patients may eventually undergo major, very painful orthopedic procedures for various fractures, wound care, and skin grafting. Elderly patients often sustain injuries to the neck of femur, ankle, or upper limbs because of accidental falls during their activities of daily living. Such falls may also occur as a result of comorbid conditions such as stroke, arrhythmia, seizures, or myocardial events, which increase the risk of routine anesthesia. Thirty percent of all traumas are sports-related and occur in the younger age group.1

Current Practice Opioids are commonly used for analgesia in the majority of patients. The trauma triage team does not need any special expertise or equipment to administer opioids. Opioids work predictably time and again. Apart from the problem of accounting for a potentially addictive controlled substance, most caregivers find them convenient to use. How well do they relieve orthopedic pain and at what price in the form of complications as well as cost? First, many patients with fracture of bones that have had internal fixation report constant burning pain in the operative site that is not relieved by even high doses of intravenous morphine (S. Ganapathy, unpublished observations). Second, physiotherapy- and activity-associated pain are also poorly relieved by opioids. There is no question that morphine is inexpensive and its use in the patient-controlled analgesia (PCA) mode may improve patient satisfaction with the quality of analgesia. However, morphine has been well documented to produce episodic nocturnal hypoxemia2 that correlates with ischemic episodes in patients with coronary artery disease.3 The side effects of nausea and vomiting prevent patients from using this modality well. It certainly can confound neurologic and other system observations in a multitrauma patient. In patients with central nervous system injuries, episodes of hypoxemia and hypercarbia are undesirable side effects. Delirium in the elderly patients with fractures of hip can be made worse by drugs administered for analgesia and nausea. On the contrary, poor pain control prevents patients from moving well and results in atelectasis and hypoxemia, which are aggravated by narcotic administration. Thus, there is a need for better acute pain management strategies in patients with orthopedic injuries.

Techniques in Regional Anesthesia and Pain Management, Vol 6, No 1 (January), 2002: pp 27-32

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Role of Continuous Catheter Regional Blocks in Orthopedic Trauma The primary role of continuous catheter regional blocks (CCBs) in orthopedic trauma is analgesia. Analgesia with the blocks is superb during rest and activity. CCBs allow substantial reductions in or eliminate narcotic use. Often patients can be managed with CCBs and oral adjuvant analgesics such as nonsteroidal anti-inflammatory drugs and acetaminophen. The side effects of narcotics, such as sedation and nausea, are significantly reduced. Early ambulation and physiotherapy may be facilitated. If a patient requires frequent dressing changes, this is performed almost pain free without additional medication. The second indication for CCBs in orthopedic trauma is in the area of reimplantation.4-6 Continuous axillary brachial plexus block has been documented to provide immobility to protect the microvascular anastomosis and improve microcirculation in traumatic amputations of digits and forearm, necessitating reimplantation. Although there has been 1 anecdotal report of ischemia in the implanted finger caused by CCB as a steal phenomenon, I have not seen this complication so far. The third area in which CCBs play a role in orthopedic trauma is in patients who develop complex regional pain syndrome (CRPS) after trauma. Although the incidence is not high, the few who develop this syndrome go through excruciating days of pain, burning, allodynia, and lack of productivity extending over several weeks. In my experience, patients with early signs of CRPS respond well to CCBs. Currently, there is no data on the role of CCBs in the management of CRPS after orthopedic trauma. CCBs have not been found to be beneficial in patients who also have associated nerve injury (CRPS type 2 or causalgia). The fourth area in which CCBs are useful in orthopedic trauma is in patients who develop joint adhesions and scar formation resulting in arthrosclerosis. These patients undergo release of contracture and bony adhesions to re-establish mobility in the joint such as the elbow and the shoulder.7 The surgery may be prolonged and is followed by the use of continuous passive motion machines and aggressive physiotherapy to maintain range of motion. CCBs may be used for such delayed complications of orthopedic trauma and are a useful modality to provide muscle relaxation and analgesia. Finally, phantom limb pain occurs in 80% to 90% of patients who require amputations of extremities after orthopedic trauma. Once established, this pain is difficult to treat.8 Fisher and Meller,9 in a pilot study, have documented in a small number of patients the total elimination of phantom pain with the use of nerve sheath continuous postoperative regional anesthesia of sciatic and posterior tibial nerves initiated at the end of surgery and continued for 72 hours. Other investigators have documented the use of CCBs to treat established phantom limb pain10-12; however, to date, there are no clinical trials evaluating

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their efficacy in pre-empting phantom pain and CRPS after orthopedic injuries. Although the nerve supply to the upper limb is compact in the form of brachial plexus, the lower limb supply is covered by 3 different groups of nerves13 that are divergent as soon as they exit the spinal canal. This necessitates multiple nerve blocks to achieve complete pain relief in the injuries of the lower limb. With the current advent of smaller portable infusion pumps, this modality of analgesia for orthopedic trauma may bring forth major economic benefits because these patients may be managed as ambulatory patients in the near future.14,15

Caveats Sedation Many CCBs are initiated with the aid of a peripheral nerve stimulator to verify the location of the tip of the needle before catheterization. In my institution, only thoracic blocks are performed without the aid of a nerve stimulator. This practice is also reflected in a recent survey by Bouaziz et al.16 This process of stimulation eliciting appropriate motor response will be painful in patients with fractures, necessitating the use of larger doses of intravenous analgesics and sedatives, such as fentanyl and midazolam, during the initiation of the block. Urmey et al17 have reported on the inability to elicit motor response consistently after eliciting paresthesia, which makes initiating these blocks in oversedated patients or under general anesthesia unsafe. In clinical practice, as long as the patient is able to obey commands and report paresthesias, lancinating pain of intraneuronal injections and tinnitus and other signs of accidental intravascular injections, sedation should not pose a problem. Once the block takes effect, patients may become oversedated because the stimulus of pain is gone and require careful monitoring. Perhaps shorter acting opiates, such as remifentanyl, may be useful in this scenario.18 Compartment Syndrome Compartment syndrome is a dreaded complication of orthopedic trauma. Unless identified early, this may result in the loss of the limb and major complications such as renal failure and death, which could result in litigation. Compartment syndrome results from tissue ischemia caused by vascular injury, use of tourniquet for surgery, intravenous regional anesthesia,19 prolonged lithotomy position,20 or prolonged hypotension after trauma. Nerve blocks21-23 and epidural analgesia24 have been reported to mask the onset of compartment syndrome. The presenting symptoms of this syndrome are pain, pallor, and paresthesia—all of which will be confounded by regional blocks. It is currently unknown if the vasodilatory effects of regional anesthesia worsen the compartment synSUGANTHA GANAPATHY

Fig 1. CCB catheter insertion systems (A and B) using a canula or a larger needle with a stimulating cable to facilitate insertion of a smaller catheter. The kits are available with needles of different lengths. The insertion hole made by the larger needle allows leakage around the smaller catheter.

drome. Although it is difficult to produce a differential blockade of the peripheral nerves (S. Ganapathy, unpublished observations), use of more dilute newer local anesthetics, such as ropivacaine, in smaller doses in CCBs may allow retention of some motor function in the blocked limb as well as allow ischemic pain to break through. Currently, there are no studies that have examined this. The second problem associated with this is the extended time it takes for the block to wear off after the infusion is held, particularly when long-acting local anesthetics are used for the CCBs to look for signs of compartment syndrome. For example, the mepivacaine block might take 4 hours to recover and bupivacaine sciatic blocks might take more than 12 hours to dissipate. It may be prudent to electively monitor compartment pressures or in high-risk patients perform prophylactic fasciotomies, which are often performed after vascular injuries and trauma.25,26 It is important that both the patient and the team managing the patient are totally aware of the possibility of compartment syndrome in the presence of CCB. Technical Problems Technical complications include catheter kinking or dislodgement, which can happen in 25% of patients, resulting in suboptimal analgesia. A majority of the CCB kits use a larger needle or canula to insert the smaller gauge

CCB catheter (Figs 1A and B). The track that is formed around the catheter tends to leak local anesthetic and eventually loosens the catheter and allows it to dislodge. Thus, a small suture to hold the catheter and tighten the insertion hole around the catheter, enclosing a loop of the catheter, provides added security with the catheter. Subcutaneous tunneling27 may also prevent dislodgement. The incidence of primary block failure is between 5% to 25%,28 and when one adds the delayed failure caused by catheter malfunction, the overall failure rate is unacceptably high in trauma patients who are likely to experience severe pain. The success rate improves with repeated use of the technique. A number of catheter hubs have a tendency to come apart at the catheter-hub junction. Fixing the connection, the catheter end, filter, and the infusion tubing over a wooden tongue depressor with waterproof tape (Fig 2) has significantly reduced the chances of disconnection in my institution. Positioning Many patients who have sustained orthopedic trauma may find it difficult to assume proper position for the blocks to be initiated. Assuming prone position for posterior popliteal or classic sciatic blocks may be painful for a patient with femoral or leg fractures. Patients with elbow and supracondylar fractures find it excruciating to

Fig 2. Technique of fixing the catheter and the infusion device tubing via a filter over a wooden tongue depressor reduces the chances of catheter disconnections.

REGIONAL BLOCK FOR ORTHOPEDIC TRAUMA

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abduct the arm for axillary block. Although leaving the limb in the temporary cast offers some comfort, often the cast interferes with seeing the motor response to nerve stimulation. Thus, trauma anesthesiologists have to have expertise with a variety of alternate techniques for various blocks. The paravascular block described by Moorthy et al,29 intersternocleidomastoid block described by PhamDang et al,30 and infraclavicular brachial plexus CCBs31-34 are useful alternatives to axillary CCB. Similarly, the anterior approach to the sciatic block described by Chelly et al35 and the lateral popliteal sciatic block36,37 are useful alternates to traditional block techniques. Femoral or fascia iliaca blocks may be substituted for the posterior lumbar plexus block. Local Anesthetic Toxicity Patients may have multiple injuries after orthopedic trauma. If trauma is confined to multiple fractures in 1 upper limb, brachial plexus block on the injured site might cover all the fractures. Whereas if trauma is in more than 1 limb, particularly in both lower limbs, adequate pain relief may be obtained only with multiple CCBs. Although there are reports of bilateral fascia iliaca blocks in trauma patients, if one were to combine femoral and sciatic blocks on both sides, the total dose of local anesthetic used to initiate and maintain the blocks far exceeds the maximum recommended dosages of local anesthetics. Studies that examine plasma levels of local anesthetics during single CCBs document levels in the region of 1 to 3 ␮g/mL of bupivacaine on average, and the highest levels occur 30 minutes after the initial bolus. Thereafter, the levels increase more gradually, reaching a steady state by 48 hours. Thus, if multiple lower limb CCBs are required, the lowest concentration and dose should be used at each site so that the cumulative dose may be within acceptable range. Often, surgery may be performed with spinal anesthesia, and the blocks may be initiated by using analgesic doses of the local anesthetic. Alternate analgesic techniques, such as epidurals and opioids, should be considered in such situations. Use of drugs with a better margin of safety with toxicity, such as ropivacaine and levobupivacaine, should be considered. I cannot emphasize adequately the importance of vigilance in monitoring patients receiving multiple blocks. In many lower limb traumas, one may use either lumbar plexus block alone (eg, injuries of femur or knee) or popliteal sciatic block alone (ankle fracture) and cover the analgesia pertaining to the unblocked areas with smaller doses of oral analgesics (narcotic sparing). It is important to avoid bolusing multiple catheters simultaneously.

Commonly Used Blocks For the upper limb injuries near the shoulder, interscalene CCB is commonly used. The front of the clavicle is supplied by the supraclavicular nerves, which are

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branches of the cervical plexus. It is important to insert the block high in the interscalene groove to get the cervical plexus. Urmey,38 in his editorial covering the report by Siverstein et al,39 has suggested accepting the deltoid twitch as an endpoint. If the fracture involves shaft of the humerus, a larger volume of local anesthetic may be required as infusion to get the lower brachial plexus roots. Combined with superficial cervical plexus infiltration, this block may be used for internal fixation of clavicle, upper end of humerus, and shoulder arthroplasty. The incidence of diaphragm paresis after this block is 100%; therefore, this block should not be used if the patient has substantial respiratory compromise in the contralateral lung. For injuries below the shoulder, supraclavicular catheters may be used with the approaches described by Moorthy et al29 and Pham-Dang et al.30 The risk of pneumothorax with supraclavicular blocks with these approaches is low. Alternatively, infraclavicular catheters, which can be secured well, may be inserted. Unfortunately, the infraclavicular catheter can slip out of the sheath with contractions of the pectoralis muscle. Infusion rates are similar to the interscalene block. For trauma at or below the elbow, I commonly use axillary CCB. A combined technique of “popping” into the fascial sheath parallel to the axillary artery at the axillary crease with a short bevel or Sprotte (Pajunk GmbH, Geisingen, Germany) needle and then verifying the position of the needle with a nerve stimulator increases the success rate. Obtaining a radial twitch facilitates catheter passage and usually 10 cm of the catheter is inserted. If the surgical incision extends into the upper medial arm or if use of a tourniquet is planned, it is important to infiltrate the intercostobrachial nerve. This area is inadequately covered by axillary block in the postoperative period, necessitating adjuvant oral analgesics. Although the area supplied by musculocutaneous nerve is often missed with single-shot axillary blocks, I do not see this often with CCBs because the catheter tip likely is higher up in the infraclavicular area. Complications include vessel trauma and hematoma, which increases the chances of persistent paresthesia. Self-limited infection at the site of insertion occurred in 2 of my patients (out of a few hundreds), with both receiving the block for more than 7 days. Kinking of the catheter with the arm adducted is a problem but resolves with positioning of the arm slightly abducted. Leakage is frequent and can be managed with pressure dressing. It is important to insert this catheter as high in the axilla as possible and allow the catheter to exit via the deltopectoral groove superiorly to keep the catheter away from the tourniquet. I often use a light general anesthesia along with the block for prolonged surgery such as digit reimplantations. For chest injuries such as multiple rib fractures or thoracotomy, although thoracic epidurals are ideal, continuous extrapleural intercostal CCB or continuous paravertebral block40 may offer a good alternative. Extrapleural SUGANTHA GANAPATHY

Fig 3. Popliteal sciatic CCB in a patient undergoing repeated dressing changes after ankle injury. Note catheter fixation with a loop under the Tegaderm (3M Corporation, St Paul, MN). The edges of the Tegaderm are secured with additional tapes.

catheters may be inserted at the end of surgery with the technique described by Richardson et al.40 In nonsurgical patients, the catheters may also be inserted percutaneously. The majority of patients obtain pain relief within a few minutes. This catheter may be used for intermittent boluses or a continuous infusion at a rate of 7 to 10 mL/h. There is a small risk of pneumothorax and interpleural catheterization. Paravertebral catheterization is performed with a Tuohy needle and an epidural catheter. The insertion is performed 2.5 cm lateral to the midpoint of the top of T2-T4 spine. The needle is walked off the transverse process, usually inferiorly with a “pop” as the superior costotransverse ligament is punctured. If one has accidentally punctured the pleura, a deep inspiration at this point may suck in the liquid from the loss of resistance syringe. There is loss of resistance to injection of saline and usually 5 cm of the epidural catheter is inserted. Recent magnetic resonance imaging evaluation reveals (S. Ganapathy, unpublished data) that 20 to 30 mL of local anesthetic covers 5 to 6 segments. The infusion rate is 7 to 10 mL/h with 10 mL boluses every 8 hours if needed. Visceral analgesia is poor with these blocks41 and therefore we either allow small doses of intravenous morphine or add 2 ␮g/mL of fentanyl with the local anesthetic infusion. This block may be initiated even in the critical care units to facilitate weaning from the ventilator. Even bilateral blocks may be used instead of thoracic epidural, but the total dose of local anesthetic use needs to be curtailed.42 Cardiac sympathectomy and mild hypotension may occur. Although posterior lumbar plexus block combined with parasacral sciatic block is ideal to cover all 3 nerves supplying the lower limb, one may need to modify the combination to anteriorly or laterally insert blocks in trauma patients. Often patients can be positioned with the aid of intravenous analgesics, such as fentanyl, in the lateral position with the operative or injured side up. Occasionally, surgery may be performed under spinal anesthesia, and these blocks may be initiated at the end of the procedure, with a small, yet unreported, risk of neurologic trauma. Although the classic lumbar plexus block is performed at the level of L4, 5 cm lateral to the spine, REGIONAL BLOCK FOR ORTHOPEDIC TRAUMA

slightly medial insertion of the needle at 3 cm allows one to contact the roots of the lumbar plexus at a much shallower depth. Depending on the size of the patient, one requires a 100 to 150 mm block insertion needle, and 5 cm of catheter inserted in the space allows for some freedom of soft tissue movement without risk of dislodgement. Lumbar plexus block alone is insufficient for hip fractures and knee injuries for anesthesia,43 but if combined with parasacral sciatic block, it may provide adequate surgical anesthesia.44 Lumbar plexus blocks have been documented to reduce operative blood loss.45,46 The problem with these blocks is the weakness of ipsilateral quadriceps and hamstrings, which prevents ambulation of patients. The lumbar plexus block acts as a compartment block, providing analgesia for 8 to 12 hours after the infusion is stopped. Side effects include urinary retention in a small number of patients and epidural and intrathecal spread of local anesthetic that may add to hypotension in trauma patients. For ankle injuries, popliteal sciatic catheters (Fig 3) may be used in combination with either subsartorial saphenous block or wound catheter infiltration to cover the area supplied by saphenous nerve. Often I use a calf tourniquet if it is forefoot surgery and a femoral block if a thigh tourniquet is used. It is important to instruct the patient about footdrop and provide protective footwear to avoid injuries to the anesthetized foot if a cast is not used. For most blocks, the usual dose for the initial block is 20 to 30 mL per site and the average infusion rate is 4 to 8 mL/h. The local anesthetic concentration may be lowered for analgesic and sympathetic blocks. Boluses followed by titration to a higher rate may be required to accomplish acceptable analgesia.

Conclusion Continuous regional blocks can contribute to enhanced comfort after orthopedic trauma with minimal side effects. Increased use of these techniques allows us to study the beneficial role of such intervention in patient outcomes after orthopedic injury. These techniques may also be used in the management of complications of orthopedic trauma such as phantom limb pain and CRPS.

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23. Noorpuri BS, Shahane SA, Getty CJ: Acute compartment syndrome following revisional arthroplasty of the forefoot: The dangers of ankle-block. Foot Ankle Int 21:680-682, 2000 24. Tang WM, Chiu KY: Silent compartment syndrome complicating total knee arthroplasty: Continuous epidural anesthesia masked the pain. J Arthroplasty 15:241-243, 2000 25. Jensen SL, Sandermann J: Compartment syndrome and fasciotomy in vascular surgery. A review of 57 cases. Eur J Vasc Endovasc Surg 13:48-53, 1997 26. Field CK, Senkowsky J, Hollier LH, et al: Fasciotomy in vascular trauma: Is it too much, too often? Am Surg 60:409-411, 1994 27. Aguilar JL, Domingo V, Samper D, et al: Long-term brachial plexus anesthesia using usbcutaneous implantable injection system. Reg Anesth 20:242-245, 1995 28. Schroeder LE, Horlocker TT, Schroeder DR: The efficacy of axillary block for surgical procedures about the elbow. Anesth Analg 83:747751, 1996 29. Moorthy SS, Schmidt SI, Dierdorf SF, et al: A supraclavicular lateral paravascular approach for brachial plexus regional anesthesia. Anesth Analg 72:241-244, 1991 30. Pham-Dang C, Gunst JP, Gouin F, et al: A novel supraclavicular approach to brachial plexus block. Anesth Analg 85:111-116, 1997 31. Spiegel P: Block of the brachial plexus. Infraclavicular transpectoral perivascular technic. Rev Bras Anestesiol 17:48-53, 1967 32. Raj PP, Montgomery SJ, Nettles D, et al: Infraclavicular brachial plexus block—a new approach. Anesth Analg 52:897-904, 1973 33. Klaastad O, Lilleas FG, Rotnes JS, et al: A magnetic resonance imaging study of modifications to the infraclavicular brachial plexus block. Anesth Analg 91:929-933, 2000 34. Mehrkens HH, Geiger PK: Continuous brachial plexus blockade via the vertical infraclavicular approach. Anaesthesia 53:19-20, 1998 (suppl 2) 35. Chelly JE, DeLaunay L, Matuszczak M, et al: Sciatic nerve blocks. Tech Reg Anesth Pain Manage 3:39-46, 1999 36. Collum CR, Courtney PG: Sciatic nerve blockade by the lateral approach to the popliteal fossa. Anaesth Intens Care 21:236-237, 1993 37. Vloka JD, Hadzic A, Kitain E: Anatomic considerations for sciatic nerve block in the popliteal fossa through the lateral approach. Reg Anesth 21:414-418, 1996 38. Urmey WF: Interscalene block: The truth about twitches. Reg Anesth Pain Med 25:340-342, 2000 39. Siverstein WB, Saiyed MU, Brown AR: Interscalene block with a nerve stimulator: A deltoid motor response is a satisfactory endpoint for successful block. Reg Anesth Pain Med 25:356-359, 2000 40. Richardson J, Lonnqvist PA: Thoracic paravertebral block. Br J Anaesth 81:230-238, 1998 41. Chan VW, Chung F, Cheng DCH, et al: Analgesic and pulmonary effects of continuous intercostals nerve block following thoracotomy. Can J Anesth 38:733-739, 1991 42. Perttunen K, Nilsson E, Heinonen J, et al: Extradural, paravertebral and intercostals nerve blocks for post-thoracotomy pain. Br J Anaesth 75:541-547, 1995 43. Chudinov A, Berkenstadt H, Salai M, et al: Continuous psoas compartment block for anesthesia and postoperative analgesia in patients with hip fractures. Reg Anesth Pain Med 24:563-568, 1999 44. de Visme V, Picart F, Le Jouan R, et al: Combined lumbar and sacral plexus block compared with plain bupivacaine spinal anesthesia for hip fractures in the elderly. Reg Anesth Pain Med 25:158-162, 2000 45. Zetlaoui P: Lumbar plexus block reduces pain and blood loss associated with total hip arthroplasty. Ann Fr Anesth Reanim 20:f7, 2001 46. Twyman R, Kirwan T, Fennelly M: Blood loss reduced during hip arthroplasty by lumbar plexus block. J Bone Joint Surg Br 72:770771, 1990

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