Femoral Nerve Block for Diaphyseal and Distal Femoral Fractures in the Emergency DepartmentSurgical Technique
By Christopher E. Mutty, MD, Erik J. Jensen, MD, Michael A. Manka Jr., MD, Mark J. Anders, MD, and Lawrence B. Bone, MD
Investigation performed at Erie County Medical Center, an affiliate of the State University of New York at Buffalo, Buffalo, New York
The original scientific article in which the surgical technique was presented was published in JBJS Vol. 89-A, pp. 2599-603, December 2007
DISCLOSURE: The authors did not receive any outside funding or grants in support of their research for or preparation of this work. Neither they nor a member of their immediate families received payments or other benefits or a commitment or agreement to provide such benefits from a commercial entity. No commercial entity paid or directed, or agreed to pay or direct, any benefits to any research fund, foundation, division, center, clinical practice, or other charitable or nonprofit organization with which the authors, or a member of their immediate families, are affiliated or associated.
BACKGROUND: Diaphyseal and distal femoral fractures are painful injuries that are frequently seen in patients requiring a trauma work-up in the hospital emergency department prior to definitive management. The purpose of this study was to determine whether a femoral nerve block administered in the emergency department could provide better pain relief for patients with femoral fractures than currently used pain management practices.
METHODS: Patients who presented with an acute diaphyseal or distal femoral fracture were identified as potential candi-dates for this study. Eligible patients were randomized by medical record number to receive either (a) the femoral nerve block (20 mL of 0.5% bupivacaine) along with standard pain management or (b) standard pain management alone (typi-cally intravenous narcotics). The pain was assessed with use of a visual analog scale at the initial evaluation and at five, fifteen, thirty, sixty, and ninety minutes following the initial evaluation. Fifty-four patients were enrolled in the study from April 2005 to May 2006. Thirty-one patients received a femoral nerve block, and twenty-three patients received standard pain management alone.
RESULTS: Baseline scores on the visual analog pain scale did not differ between the groups at the initial evaluation. The patients who received a femoral nerve block (along with standard pain management) had significantly lower pain scores at five, fifteen, thirty, sixty, and ninety minutes following the block than did the patients who received standard pain man-agement alone (p < 0.001). The score on the visual analog pain scale across these time points was an average of 3.6 points less (on a 10-point scale) for those who received the block. There were no infections, paresthesias, or other com-plications related to the femoral nerve block.
CONCLUSIONS: The acute pain of a diaphyseal or distal femoral fracture can be significantly decreased through the use of a femoral nerve block, which can be administered safely in the hospital emergency department.
LEVEL OF EVIDENCE: Therapeutic Level II. See Instructions to Authors for a complete description of levels of evidence.
ORIGINAL ABSTRACT CITATION: “Femoral Nerve Block for Diaphyseal and Distal Femoral Fractures in the Emergency Depart-ment” (2007;89:2599-603).
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INTRODUCTIONIn most emergency depart-ments, the pace is fast and there is a constant flow of personnel. Amid all of this activity, address-ing the acute pain of a femoral fracture may not be a top prior-ity. However, most patients use descriptors such as “excruciat-ing” or “the worst pain imagin-able” when describing the acute pain that they experienced in as-sociation with a femoral fracture. A femoral nerve block can pro-vide effective pain relief and can be delivered safely in the emer-gency department with the ap-propriate equipment and education of the staff.
SURGICAL TECHNIQUEAfter the primary and second-ary assessments have been completed and it has been deter-
mined that the patient does not require an immediate trip to the operating room, temporary sta-bilization of orthopaedic injuries is undertaken in the form of splinting or traction. Concur-rent with this process, the ortho-paedic surgeon should perform a careful neurovascular exami-nation of the extremities. Dorsa-lis pedis and posterior tibial pulses are palpated. The patient should demonstrate intact ante-rior tibialis, extensor hallucis longus, gastrocnemius/soleus, and toe flexor motor function as surrogates for the integrity of the peroneal and tibial divisions of the sciatic nerve. In addition, sensation across the dermatomes of the injured lower extremity is assessed. These are critical first steps in deciding whether a pa-tient is an appropriate candidate
for a femoral nerve block. Pa-tients with abnormal findings on the neurovascular examination or those who are unable to par-ticipate in the examination are not candidates for a nerve block. The thigh on the affected side should be carefully examined. Patients with a rigid, tensely swollen thigh or those with a rapidly expanding hematoma are also not candidates for a re-gional block. The history of the injury is then reviewed. If the history is consistent with a mechanism that places the pa-tient at high risk for compart-ment syndrome (such as a crushing injury or a prolonged extrication secondary to an entrapped lower extremity), then a femoral nerve block is contraindicated.
Once it has been deter-
FIG. 1
Nerve stimulator and injection kit.
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mined that the patient is a suit-able candidate for a regional block, the risks and benefits of the procedure are explained to the patient in straightforward terms. If the patient wishes to proceed with the block, a nerve stimulator and an injection kit are set up at the bedside (Fig. 1). The stimulator and injection kits should be maintained in a secure and convenient location to en-sure that the stimulator is in good working order and that the contents of the kit have not ex-pired. Typically, there will be a lot of activity around the pa-tient; it is important that all members of the trauma team be familiar with the nerve block procedure so that efforts such as ensuring appropriate resuscita-tion, blood drawing, and Foley
catheter placement can be coor-dinated with the administration of the block. The injection kit is opened, and the contents are re-viewed to ensure that nothing is missing (Fig. 2) (see Appendix for a complete list of supplies). The protective cap on the 30-mL bottle of 0.5% bupivacaine is re-moved, and the expiration date is checked. The stimulator is turned on and is checked for ap-propriate settings; generally, a current of 0.8 mA at 2 Hz will provide an excellent visual (pa-tellar twitch) cue that the needle tip is in the immediate vicinity of the femoral nerve without caus-ing increased pain for the pa-tient. The stimulating needle package is opened, and the tub-ing and wire are carefully re-moved so as to maintain sterility
of the needle. The wire from the needle is connected to the stimu-lator lead. Twenty milliliters of bupivacaine are drawn into the 35-mL syringe with use of the 18-gauge needle. This needle is then removed, and the stimula-tor needle and tubing are at-tached to the syringe. The electrocardiogram electrode is placed on the patient’s abdo-men, and the grounding clip from the stimulator is connected. The Mayo stand or table on which the equipment is placed should be positioned immedi-ately adjacent to the stretcher on the patient’s affected side at the level of the upper abdomen so the stimulator will be clearly visi-ble and the equipment will be within easy reach (Fig. 3).
Landmarks on the patient
FIG. 2
Contents of the nerve block kit: stimulating needle assembly, 35-mL syringe, 18-gauge needle, 25-gauge needle, prepackaged lidocaine sy-ringe, grounding electrode (with spare), povidone-iodine swabsticks (three), sterile gloves, 30 mL of 0.5% bupivacaine.
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are palpated (Fig. 4-A). The in-guinal ligament is palpated from the anterior superior iliac spine to the pubic tubercle. The femo-ral artery pulse is then located 3 to 4 cm distal to the inguinal lig-ament (at the level of the in-guinal crease). The femoral nerve is lateral to the artery (Fig. 4-B), and this location is marked with a pen. A small indentation can be made with a pen cap so that the location will be visible after ster-ile preparation of the skin. The groin on the affected side is then prepared with povidone-iodine swabsticks. The skin at the marked site is anesthetized with the injection of approximately 0.5 mL 2% lidocaine with use of the preloaded 5-mL syringe and 25-gauge needle provided in the kit, resulting in a wheal (Fig. 5). Sterile surgical gloves are donned
after it has been verified that all connections have been made and the stimulator has been turned on. The stimulating needle is withdrawn from its package and, with one hand being used to sta-bilize the skin, the needle is ad-vanced through the skin at the previously made mark. The stim-ulating needle has a relatively blunt tip that requires quick, firm, and controlled pressure in order to penetrate the skin. The needle is then slowly advanced with the tip angled about 30° cephalad. The femoral nerve has a proximal branch that extends to the sartorius, and this muscle often will be the first to exhibit a twitch in synchrony with the stimulator’s audio tone and flashing indicator. The needle should continue to be advanced until the patella is noted to
twitch in concert with the cues from the stimulator. At this point, in a patient with an aver-age body habitus, the needle tip typically has been advanced 2 to 3 cm and is in the immediate vi-cinity of the femoral nerve. If the needle is advanced and no twitch is elicited, the needle should be withdrawn to the level of the skin and reinserted in a slightly more lateral direction. In order to avoid penetration of the femoral artery, the needle should never be redirected medially toward the fingers lying over the pulse of that vessel. Once the patellar twitch has been elicited, the nee-dle is stabilized in position with one hand and the syringe is picked up with the other hand (Figs. 6-A and 6-B). An attempt at aspiration is first made to en-sure that the needle is not within
FIG. 3
Patient and equipment positioning.
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FIG. 4-A
Regional landmarks. A = anterior su-perior iliac spine, B = pubic tubercle, and C = inguinal crease.
FIG. 4-B
Pertinent underlying anatomical structures in-clude the femoral nerve, artery, and vein; the inguinal ligament; and the sartorius, iliop-soas, and pectineus muscles.
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the artery (signified by the pres-ence of easily aspirated bright red blood). If the needle has been in-advertently advanced into the ar-tery, it should be withdrawn and pressure should be applied for five minutes before resuming the procedure. Approximately 1 to 2 mL of bupivacaine are slowly in-jected, and the patellar twitch should stop at this point. If the patient experiences a sudden in-crease in pain or if the patellar twitch continues, the needle tip may be within the nerve itself and should be withdrawn slightly. The remainder of the bupivacaine is then injected in a controlled fashion over the course of sixty seconds. Aspira-tion is attempted periodically to verify that the needle is not within a blood vessel, and the pa-
tient is asked about the develop-ment of circumoral numbness, tinnitus, or blurred vision. Any of these symptoms may indicate an intravascular injection, and the procedure is discontinued if this occurs. After 20 mL of bupi-vacaine have been injected, the needle is withdrawn, the site is checked for bleeding, and the stimulator is returned to the ap-propriate location.
Most patients begin to re-port a diminution of pain within five minutes and experi-ence more than ninety minutes of effective pain relief with a sat-isfactory femoral nerve block. The trauma team initially may be apprehensive about the block being performed early in the process of the trauma workup. Through education with an at-
tending anesthesiologist and the acquisition of good technical skills, junior residents at our in-stitution have been able to per-form the block safely and efficiently and there have been no cases in which the procedure was a rate-limiting step in the patient’s evaluation. By provid-ing the block before transport-ing the patient to the radiology department, we are able to pro-vide effective pain relief when it is needed most—during trans-fers to and from the imaging ta-bles. The duration of pain relief beyond ninety minutes is less well defined; however, on the basis of the 3.5-hour half-life of bupivacaine in adults, the effect can be expected to last through-out the duration of the trauma evaluation.
FIG. 5
Injection of 2% lidocaine at the anticipated site of stimulating needle placement.
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FIG. 6--A
Localization of the femoral nerve with the stimulating needle. The palpating hand is positioned with the fingers overlying the femoral artery pulse. The patella (shown covered in this image) should be visible during this process so patellar twitch can be seen.
FIG. 6-B
Administration of the block.
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CRITICAL CONCEPTS
INDICATIONS:
Femoral nerve block placement in the emergency department has been shown to be effective during the treatment of dia-physeal and/or distal femoral fractures (both closed and open) in awake and alert adults who are able to respond appro-priately to questions and who have a normal neurovascular examination of the injured extremity.
CONTRAINDICATIONS:
• Intubated or obtunded patients or other patients who are not able to respond to questions and follow commands, thereby precluding an adequate examination.
• Patients with an injury history that is consistent with a crushing or other mechanism that places them at increased risk for compartment syndrome.
• Patients with physical examination findings that are consistent with compartment syndrome or impending compartment syndrome.
• Patients with an abnormal neurovascular examination or an unstable spine injury.
• Patients with a history of a bleeding diathesis or an abnormal coagulation profile associated with a potential risk for the development of an injection site hematoma.
PITFALLS:
• Inability to access the necessary equipment in a timely fashion. This pitfall can be avoided through communication with the emergency department staff and the trauma team before implementation of the technique and by performing a “dry run” of the procedure in the trauma bay before performing it in a tense environment with an actual trauma patient.
• Local anesthetic toxicity. This pitfall can complicate regional anesthetic techniques secondary to two primary mecha-nisms. Either the administration of an excessive amount of local anesthetic or inadvertent intravascular injection can result in severe patient compromise. Gross overdose is readily avoided by adhering to maximum dosing guidelines; in this case, no more than 3 mg/kg of bupivacaine is injected into the perineural space. As an example, an 80-kg patient may safely receive 240 mg of bupivacaine (48 mL of a 0.5% bupivacaine solution). Note that this dose represents a true minimum toxic dose yet is >50% greater than the dose that was delivered in our study population. Substantially lower doses can produce toxic responses if injected intravascularly. Intravascular injection is avoided by frequent aspi-ration for blood and incremental injection with continuous monitoring for signs of toxicity such as tinnitus, circumoral numbness, tachycardia, nystagmus, and central nervous system excitation or depression. Current approaches to the management of local anesthetic toxicity include the selection of less toxic alternatives, such as ropivacaine or levobupivacaine, ultrasound guidance to identify and avoid vascular structures, and the immediate availability of a lipid emulsion such as Intralipid (Fresenius Kabi, Uppsala, Sweden). A lipid emulsion acts as a lipid sink for the fat-soluble local anesthetics. Use of this agent has resulted in markedly improved survival after local anesthetic overdose-induced cardiac and central nervous system dysfunction1. Unidentified intravascular injection or gross overdose are unlikely events when this procedure is performed while carefully following the technique as described; neither has been re-ported in the peer-reviewed literature, to our knowledge.
• Technical pitfalls, including equipment failure. A battery that lacks a full charge or improper electrical connections can result in inadequate current delivery and failure to elicit a twitch response. The former problem can be prevented by en-suring that the stimulator is maintained with a charged battery. The latter problem can be avoided by understanding the circuit between the patient and the stimulator required for proper stimulator function. Current delivery depends on a closed circuit. If the light-emitting diode fails to flash, the electrocardiogram electrode and the wire connections should be checked.
• Injection of anesthetic too far distant from the femoral nerve. As mentioned above, the branch of the femoral nerve to the sartorius muscle tends to arise anterior to the main trunk of the femoral nerve. The sartorius twitch response is frequently encountered en route to the true quadriceps twitch of the femoral nerve itself. Premature injection on the sartorius twitch will result in an excellent block of the sartorius but a failed femoral nerve block, which will provide inad-equate anesthesia. Elicitation of a true quadriceps twitch is essential.
continued
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APPENDIX: FEMORAL NERVE BLOCK SUPPLIES
1. Peripheral nerve stimulator (STIM300; B Braun Medical, Bethlehem, Pennsylvania).
2. Stimuplex insulated needle (STIM-A2250; B Braun Medical, Bethlehem, Pennsylvania).
9. 18-gauge 1.5-in (3.8-cm) sterile needle (#305196; BD, Franklin Lakes, New Jersey).
10. 25-gauge 5/8-in (1.6-cm) sterile needle (#305122; BD, Franklin Lakes, New Jersey).
NOTE: The authors thank Mark Barnett and Van Sikes fortheir assistance with the preparation of the figures for thisarticle.
Christopher E. Mutty, MDDepartment of Orthopaedic Surgery, Wake Forest University Health Sciences, Medical Center Boule-vard, Winston-Salem, NC 27157. E-mail address: [email protected]
Erik J. Jensen, MDMichael A. Manka Jr., MDMark J. Anders, MDLawrence B. Bone, MDDepartments of Anesthesiology (E.J.J.), Emergency Medicine (M.A.M. Jr.), and Orthopaedic Surgery (M.J.A. and L.B.B.), Erie County Medical Center, 462 Grider Street, Buffalo, NY 14215
The line drawings in this article are the work of Jennifer Fairman ([email protected]).
REFERENCES1. Whiteside J. Reversal of local anaesthetic induced CNS toxicity with lipid emulsion. Ana-esthesia. 2008;63:203-4.
2. Auroy Y, Benhamou D, Bargues L, Ecoffey C, Falissard B, Mercier FJ, Bouaziz H, Samii K. Major complications of regional anesthe-sia in France: The SOS Regional Anesthesia Hotline Service. Anesthesiology. 2002;97:1274-80. Erratum in: Anesthesiology. 2003;98:595.
3. Brull R, McCartney CJ, Chan VW, El-Beheiry H. Neurological complications after regional anesthesia: contemporary estimates of risk. Anesth Analg. 2007;104:965-74.
4. Dingemans E, Williams SR, Arcand G, Chouinard P, Harris P, Ruel M, Girard F. Neuro-stimulation in ultrasound-guided infraclavicu-lar block: a prospective randomized trial. Anesth Analg. 2007;104:1275-80.
CRITICAL CONCEPTS
PITFALLS (CONTINUED):
• Prolonged paresthesias in the femoral nerve distribution. This complication has been reported to occur very rarely, with an incidence of 0.03%2. Brull et al. recently reported on neurological complications after regional anesthesia3. Their review of 13,378 femoral nerve blocks from four studies revealed fifty-two instances of prolonged paresthesias and one case that had failed to resolve completely after twelve months. The cause of this complication is most likely multifactorial and may be due to direct nerve injury, compression by hematoma, or local anesthetic toxicity. While this complication has been shown to be rare, it should be included in the discussion of risks and benefits with the patient.
AUTHOR UPDATE:
Current data suggest that the utilization of ultrasound-guided nerve localization hastens, simplifies, and improves the ac-curacy of regional anesthetic/analgesic techniques4. This technique has not been reported in the emergency department scenario and is not currently used in our facility. Our results with the simple nerve stimulator technique for nerve localiza-tion demonstrated that this method is effective. Nevertheless, ultrasound is being used for regional anesthesia needle guidance in the elective setting and, if it can be carried out as efficiently in the emergency department setting as is the technique of localization with the use of the nerve stimulator, a future study comparing the effectiveness of the two tech-niques will be undertaken.
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