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Conduction anesthesia of the lower extremityA technique and literature review CHARLES A. REESE, CRNA, PhD San Diego, California The author reviews the history, anatomy, and techniques (complete with step-by-step illustrations) for conduction anesthesia of the lower extremity. This is part of the continuing series on conduction anesthesia papers that were presented at the 44th AANA Annual Meeting and ProfessionalSessions held during August, 1977, in Hollywood, Florida. While conduction anesthesia for the lower extremity has not enjoyed as colorful a history or as enthusiastic support as similar techniques for the upper extremity, certain commonalities may be discerned. Possibly the first recorded attempts to produce insensibility of the lower extremity was Hippocrate's application of snow and ice to treat hemmorhage and muscle sprain. 1 Baron von Larey, Napoleon's surgeon general, noted a decrease in pain associated with amputation in soldiers who had lain wounded in battlefield snow for prolonged periods. 2 Such refrigeration techniques prevail today in only limited application and are generally topical ether or ethyl chloride sprays. Such techniques are painful to apply, work only superficially for short periods of time and may cause irreversible necrotic tissue changes. In 1784, George Moore described an elaborate device by which he could June/1978 apply compression to vessels and nerves of the lower extremity to produce pain relief.8 Such attempts were apparently short lived, as little is seen of them after this time. The first attempt at chemical conduction anesthesia was Taylor's application in 1839, of a morphine paste placed subcutaneously near the vicinity of major nerves.4 While any analgesia that was realized was probably more due to the systemic effects of the morphine than to diminished nerve conduction, the concept of nerve blocking was being developed. Alexander Wood's development of the hollow metallic needle and syringe in 1855, 5 along with Gaedicke's isolation of cocaine, 6 ushered in the age of "local anesthetization." While probably in limited use, it would prove to be nearly 30 years before reports appeared introducing such techniques. In 1884, Carl Koeller 7 and William Burke8 described topicalization and intermuscular paraneural injection of cocaine, respectively, to produce surgical anesthesia. By 1885, more than 60 formal papers, including Halstead's 9 classic article espousing regional anesthesia, had lauded the use of cocaine. In 1892, Schleich 10 introduced the use of dilute cocaine solutions for massive "infiltration" techniques for virtually all types of surgical procedures. Late in the nineteenth century, numerous reports of "poisoning" and shock following the injudicious use of cocaine resulted in a widespread search 237 for less toxic agents. Braun, 11 in 1901, suggested the addition of dilute epinephrine to the infiltration solutions-the effect being to slow the circulatory uptake and thus decrease the central nervous system effects seen with high circulating blood levels of cocaine. In 1899, Einhorn 12 synthesized procaine; however it was 1905 before Braun 18 popularized it for regional techniques. The introduction of procaine, which was less toxic and longer lasting than cocaine, gave rise to the development and introduction of numerous regional nerve block techniques -the most popular of which was the subcutaneous infiltration of the surgical site, both with and without the use of general inhalation anesthesia (ether). Several significant developments, including the introduction of spinal anesthesia by Bier 14 in 1898, demon- stration of caudal anesthesia by Sicard"1 in 1901, and the popularization of peridural anesthesia by Pages16 in 1920, have served to inhibit somewhat the widespread use of the various specialized blocks of the lower extremity. As surgical techniques became more sophisticated, there arose a similar need for increased sophistication in anesthesia. Most conduction anesthesia tech. niques for the lower extremity were developed during the 1920's and 193 0 's by such notable authors as Pitkin 17 and Labat 18 ; these techniques have withstood the test of time. Many "modern" techniques are simply modifications of these originals made possible by a better understanding of applied anatomy and the pharmacokinetics of the more recently developed chemical agents. In this review article, the author makes no attempt to give or deny spe- Figure 1. The lumbar plexus is formed by the fir lt four lumbar nerves between the quadratus lumborum and psoas major muscles. Ouadratus lumborum m. Iliohypogastric n. Illoingulnal n. Genltofemoral n. Lat. femoral cutaneous n. Psoas major m. Iliacus m. Femoral n. Obturator n. (Reprinted with permission from the article by Alon P. Winnie, MD, et al, "The Inguinal Paravascular Technique of Lumber Plexus Anesthesia," Anesthesia and Analgesia, Vol. 52, Nov-Dec, 1973.) Journal of the American Association of Nurse Anesthetists oific credit for the techniques described but rather attempts to delineate several conduction anesthesia techniques, as modified, of the lower extremity which are currently employed at his institution. Thus, the intent is to attempt to revitalize techniques which may have been overshadowed by the frequent employment of spinal or epidural anesthesia in the practice of most anesthetists. As in all conduction anesthesia techniques, a keen appreciation of the anatomy involved is a fundamental prerequisite (sine que none). The anesthetist must first realize that the lower extremity, unlike the upper extremity, is supplied by major nerves which take origin from two separate, but related, central nerve plexus, namely the lumbar plexus and the sacral plexus. Lumbar plexus The lumbar plexus is formed by the mergence of the roots of the first four lumbar nerves. 19 (See figure 1.) It lies anterior to the quadratus lumborum muscle and either posterior to or within the fascial sheath of the psoas major muscle and gives rise to the three primary nerves of the lower extremity. The first nerve to emerge is the lateral femoral cutaneous nerve which contains elements of L2 and L3. This nerve courses across the iliacus muscle Figure 2. Cutaneous sensory innervation provided by the lateral femoral cutaneous nerve. LATERAL ANTERIOR POSTERIOR ky June/1978 MEDIAL ^nom 239 obliquely toward the anterior superior iliac spine of the pelvis and then passes below the lateral end of the inguinal ligament. The lateral femoral cutaneous nerve provides sensory innervation to the lateral thigh (figure 2) and has no motor function. The second nerve to emerge from the lumbar plexus is the obturator nerve which is formed by the anterior primary divisions of the second, third, and fourth lumbar nerves. The nerve runs within the substance of the psoas major muscle along the posterior wall of the abdomen and lateral to the hypogastric and iliac vessels. It traverses through the pelvis and enters the lower extremity via the obturator foramen where it then divides into anterior and posterior branches. In approximately one-third of the population, an "accessory obturator" nerve is present. 20 It is formed from the third and fourth lumbar nerves and runs tangential to the psoas major muscle to the posterior edge of the pelvis. It then traverses the pelvis and passes anterior to the superior ramus of the pubis where it merges with the anterior branch of the obturator nerve. The sensory component of the obturator nerve supplies the cutaneous aspect of the medial thigh as far down as the knee. (See figure 3.) Additionally, Figure 3. Cutaneous sensory innervation provided by the obturator nerve i. This nerve additionally gives rise to articular branches to the hip and knee joints. LATERAL ANTERIOR 240 ; POSTERIOR MEDIAL Journal of the American Association of Nurse Anesthetists the anterior branch contributes an articular branch to the hip joint while the posterior branch supplies a similar articular branch to the knee joint. Block of the obturator nerve is essential when use of an upper-leg tourniquet is anticipated or the proposed surgery entails manipulation of the hip and/or knee joint. The last nerve to emerge from the lumbar plexus, the femoral nerve, is its largest constituent and is formed by the mergence of the anterior primary divisions of the second, third, and fourth lumbar nerves. (See figure 1.) The formed nerve descends from the plexus in a groove created by the psoas major and iliacus muscles. It enters the thigh by passing behind the inguinal ligament anterior to these muscles and lateral to the femoral vessels where it immediately divides into two brush-like bundles-an anterior and a posterior branch. The anterior or superficial branch contains the sensory components which supply the anterior and medial aspect of the thigh as far down as the knee. (See figure 4.) The posterior or deep branch contains the motor fibers which innervate the quadriceps and the articular fibers which innervate the hip Figure 4. Cutaneous sensory innervation provided by the femoral nerve. This nerve additionally gives rise to the saphenous nerve which provides cutaneous sensory innervation to the medial aspect of the lower leg to the medial malleolus. LATERALTJ ANTERIOR June/1978 POSTERIOR MEDIAL 241 and knee joint. It additionally gives rise to the saphenous nerve which supplies cutaneous innervation of the medial aspect of the lower leg to the medial malleolus. As with the obturator, the femoral nerve must be blocked when using an upper-leg tourniquet or performing manipulation of the knee or hip joint. From the anatomical relationships previously mentioned, certain consistent "landmarks" can. be described from which geometrical projections can be visualized in order to facilitate isolation of specific nerves and subsequent performance of percutaneous conduction anesthesia techniques. One such landmark, which is common to block techniques of the three nerves presented, is the inguinal (Poupart's) ligament. With the patient lying in the supine position, a mark is made on the skin from the anterior superior iliac spine to the pubic symphysis (figure 5), as these are the boney attachments of this important ligament. Additional landmarks will be described separately for each of the specific nerves. Lateral femoral cutaneous nerve block We have noted earlier that the lateral femoral cutaneous nerve passes beneath the lateral end of the inguinal ligament before entering the muscle mass of the lateral thigh. An intradermal skin wheal is made with .5% Xylocaine® HC1 approximately / 2 -inch medial to the anterior superior iliac spine and approximately 1/ 2 -inch below the inguinal ligament (figure 6). A sterile /4-inch 23-gauge hypodermic needle, Figure 5. The inguinal (Poupart's) ligament provides an important anatomical landmark for lower extremity nerve block techniques. It attaches to the pubic tubercle and the anterior superior iliac spine. If ,- ll A4 nctrb IrquI rta Fero rAl nervC vetn 3urfoce iondre&rk3: Art. sup. spinec Point of 1rlctclor' Pubic, bubercltc " (Reprinted with permission from the book, Regional Block, 4th Edition, by Daniel C. Moore, MD, Charles C. Thomas Publisher, Springfield, III., 1965.) Journal of the American Association of Nurse Anesthetists attached to a sterile 10-cc syringe filled it has not proven necessary to expose with an appropriate anesthetic agent, patients to multiple needle sticks when is placed through the skin wheal and but one, placed as described, will suffice. slowly advanced until a "pop" or loss As the lateral femoral cutaneous of resistance is perceived as the needle nerve contains no motor fibers, conpasses through the tough membranous firmation of impending nerve block can fascia lata. With the needle thus propbe assessed by the presence of sensory erly placed, the syringe is aspirated to changes in the cutaneous area within obviate intravascular injection and 8-10 3-5 minutes, depending upon which cc of the anesthetic agent is injected. which agent and concentration is used. A feeling of resistance upon injecting (See figure 2.) should alert the anesthetist that he/she Femoral nerve block is injecting into muscle mass and not As was noted previously, the fethe desired fascial plane in which the moral nerve passes under the inguinal lateral femoral cutaneous nerve is found. ligament anterior to the iliacus and psoas major muscles and lateral to the Some authors 21- 24 advocate the use femoral vessels. These important strucof multiple injections to achieve a "fantures are separated by the thickened ning" pattern when attempting this block. It is the author's experience that iliopectineal fascia and a slip of the Figure 6. Anatomical landmarks and a technique for performing a block of the lateral femoral cutaneous (LFC) nerve. Additional skin markings represent the location at which blocks are performed for the femoral (FN) nerve and obturator nerve (ON). Other markings include: PS, pubic symphysis (tubercle); AS, anterior superior iliac spine. i ^y^-. "a ' w 1^ ^ ^-- am- / 4< C. gfF (Reprinted with permission from the book, Regional Block, 4th Edition, by Daniel C. Moore, MD, Charles C. Thomas Publisher, Springfield, III., 1965.) June/1978 psoas major muscle. (See figure 7.) Pulsation of the femoral artery is palpated and a skin wheal is made approximately 1/2 -inch lateral to the pulse and distal to the inguinal ligament. (See figure 6.) This location is directly anterior to the femoral nerve prior to its division. A sterile 1/ 4 -inch 21-gauge hypodermic needle with a sterile 10-cc syringe, filled with an appropriate anesthetic agent, is placed through the skin wheal. One lead of a commercially available "peripheral nerve stimulator" is attached to the needle with a small "alligator" clip while the second lead is clipped to an adhesive EKG pad placed elsewhere on the patient's body. 25 (Figure 8.) With the stimulator's output at the desired level and the frequency set at one stimulation per second, the needle is slowly advanced perpendicular to the skin until involuntary contractions of the quadriceps muscles are noted in unison with the stimulator's pulsation. This will indicate that the needle tip has reached the level of the posterior branch of the femoral nerve. Occasionally, a patient will per. ceive a paresthesia radiating to the anteriomedial thigh. This indicates that Figure 7. A cross section at the level of the left inguinal ligament to demonstrate the fascial "sheath" surrounding the femoral nerve. Note the iliopectineal fascia (unlabeled) and small portion of the psoas major muscle which separate the femoral nerve and vessels. -^list\\ i./kL^\1 rMmfw duge 'TI Obtu r a. wame s V. and a. Psoes major m. (Reprinted with permission from the article by Alon P. Winnie, MD, et al, "The Inguinal Paravascular Technique of Lumbar Plexus Anesthesia," Anesthesia and Analgesia, Vol. 52, Nov-Dec, 1973.) Journalof the American Association of Nurse Anesthetists Figure 8. Demonstration of author's technique for isolating and blocking the femoral nerve. Note use of the peripheral nerve stimulator as described in text. directly at the nerve, and the remaining 7-8 cc of the agent are injected. The absence of this fade is indicative that the needle tip has been placed either too shallow or too deep (figure 9). Figure 9. When utilizing the peripheral nerve stimulator for isolating peripheral nerves, maximum electrical output is concentrated at the tip of the needle. (Top to bottom) Needle approaching nerve; needle at level of nerve; needle past nerve but still capable of eliciting response. the anterior branch of the femoral nerve has been located. Solicitation of this paresthesia is not considered essential when utilizing the nerve stimulator technique but will indicate that the needle is approaching the desired location. Indeed, nerve damage may result from overzealous probing for paresthesias, its cause being either blunt trauma from the needle or stretching of nerve fibers from direct intraneural injection of anesthetic agent. 26 The needle is slowly advanced or withdrawn until maximum contractions are observed. The syringe is aspirated to obviate intravascular injection; and with the stimulator still in use, a test dose of 2-3 cc of the desired anesthetic agent is injected. The anesthetist should observe the anterior thigh (quadriceps) for immediate (10-15 seconds, depending upon the type and concentration of agent used) dimunition or "fade" of muscle contractions. This "fade" is taken as evidence that the needle is June/1978 Continued injection at these levels may hamper further attempts to isolate the nerve with electrical stimulation. The needle should be slowly repositioned until maximal contractions are again observed. The test-dose/muscle fade sequence is then repeated prior to injecting a final dose. If the femoral vessels are entered, as occasionally occurs, the needle is withdrawn from the patient and compression is applied for 5-10 minutes to minimize hematoma formation. Sensory distribution of the femoral nerve is graphically illustrated in figure 4 and can be clinically evaluated with an alcohol sponge or needle point. Testing motor function provides a more reliable and objective indicator of the onset and completeness of block. As the femoral nerve provides motor innervation to the quadriceps muscles, the anesthetist can evaluate the block by holding the patient's leg as demonstrated in figure 10 and instructing him to attempt to extend or "straighten" his lower leg against resistance. The dimunition or inability of the patient to extend his leg in this fashion is taken as an in dication of ensuing block. Depending on the type and concentration of agent(s) employed, onset of block should be evident in 3-5 minutes, with surgical anesthesia being present in 15-20 minutes. Duration, of course, will be dependent upon the agent, concentration, and presence or absence of vasoconstrictors. The use of electrical stimulation to locate and isolate peripheral nerves has been described by numerous au- thors 27 84 but apparently does not enjoy wide popularity in the practice of regional anesthesia. Since its introduction by von Perthes, 8 5 in 1912, the technique has found its primary acceptance by neurophysiologists for research and neurologists for diagnostic examinations. It has been shown that motor fibers are stimulated at a threshold lower than that necessary to stimulate sensory fibers. 27 This allows discreet identification of individual peripheral nerves at electrical voltages which create no discomfort for the patient. It should be emphasized, however, that involuntary contraction and subsequent movement of a traumatized extremity may cause considerable pain. Therefore, when Figure 10. To evaluate onset and degree of motor loss following block of the femoral nerve the anesthetist holds the patient's leg in the manner demonstrated. As the femoral nerve provides motor innervation of the quadriceps muscle group, the patient's inability to "straighten his leg" (flexion of quadriceps) against resistance is taken as indication of ensuing block. Journalof the American Association of Nurse Anesthetists utilizing this technique, the anesthetist is advised that the stimulator should be discontinued as soon as the desired nerve is isolated and resumed only to initiate the test-dose/fade sequence. Early reports 274 8 concerning this technique described specially prepared needles which had been coated with insulating materials, leaving only the tip of the needle exposed. The apparent belief was that this design would maximize the electrical density at the tip of the needle and prevent "leaking" current along the shaft from stimulating muscle or nerve fibers causing misinterpretation of results. Montgomery and coworkers 84 showed that a minimum of 30% of all current passed into an uninsulated needle will concentrate and exit through the tip. Likewise, in our clinical practice, we have found that commercially available uninsulated hypodermic or spinal needles are satisfactory with this technique. We presently employ the Peripheral Nerve Stimulator® (BurroughsWellcome) which is a transistorized, battery powered device. Voltage output varies linearly with load resistance (20 volts at 1000 ohms). The markings on the case represent lineal voltage progressions of approximately 10% (that is, the fourth mark is equal to 8 volts). No alterations to this unit are required or recommended. We have removed the terminal connectors supplied with the electrode wires and attached small "alligator" clips (available from any electrical supply house). When in use, one clip is attached to the shaft of the probing needle, the other is attached to the metal snap of a disposable EKG pad. 25 We have found that a setting of 2-6 Figure 11. Demonstration of involuntary muscle contraction caused by isolation of peripheral (sciatic) nerve with electronic nerve stimulator as described in text. Immediate diminution ("fade") of this response following injection of 1-3 cc of local anesthetic agent is evidence of proper needle placement. June/1978 volts is required to stimulate the major peripheral nerves and will do so only when the needle tip is approximately 3 mm from the nerve substance, 84 a distance which is compatible with localizing nerves of this size. Figure 11 demonstrates the movement noted from involuntary contractions of the extensors of the lower leg when the sciatic nerve has been isolated with the electric nerve stimulator. Utilization of the nerve stimulator technique, as described, will yield a higher success rate than those which rely solely on the presence of a paresthesia. Such success, no doubt, will instill confidence in students and insure their continued support of regional anesthesia. In addition, this technique allows the performance of conduction anesthesia for heavily sedated, inebriated, comatose, senile, or psychotic patients. Obturator nerve block We have noted that the obturator nerve is best accessible where it enters the obturator foramen of the pelvis. An intradermal skin wheal is made approximately 1-inch below the inguinal ligament and 1-inch lateral to the pubic symphysis (figure 12). A sterile 32inch 20-gauge (spinal) needle with a movable depth indicator is placed through the skin wheal and is slowly advanced until resistance (the superior ramus of the pelvis) is encountered. At this point, the depth indicator is posi-inch from the tioned approximately skin, and the needle is withdrawn to the subcutaneous tissues. The needle is redirected slightly lateral and caudad while being slowly advanced until either bone again is encountered or, if no bone is felt, the depth indicator comes to rest at the skin level. Occasionally, a patient will indicate a paresthesia radiating to the medial aspect of the thigh; however, purposeful solicitation of this paresthesia is not essential to successful performance of this block. At least one author has advocated the use of electrical stim- Figure 12. Anatomical landmarks and technique of injecting the obturator nerve. The needle in Position 1 rests against the inferior ramus of the pubic bone. In Position 2, it has been "walked off" the ramus to rest in the upper inner portion of the obturator foramen. Injection is made at this location. .Obturc,tor ni. . 2Obturator f oro re .5uperior rarnus n of pubic, bone, (Reprinted with permission from the book, Regional Block, 4th Edition, by Daniel C. Moore, MD, Charles C. Thomas Publisher, Springfield, III., 1965.) Journalof the American Association of Nurse Anesthetists 80 ulation to isolate the obturator nerve. We have been unable to reproduce the results advocated in this article. Following placement of the needle as described, a sterile syringe is attached to the needle and aspirated to obviate intravascular injection, and 10 cc of anesthetic agent is injected. When properly positioned, the tip of the needle rests in a semi-closed space, formed superiorly by the ramus of the pubis, and inferiorly medially, and laterally by the obturator internus and externus muscles. These form a "potential space" around the obturator nerve; therefore, the anesthetist should encounter little or no resistance upon injection. However, if such resistance is encountered after injection of 1-3 cc, the tip of the needle is intramuscular and should be repositioned. The motor component of the obturator nerve innervates the adductors of the leg; therefore, the inability of the patient to adduct his blocked leg against resistance will indicate the onset of chemical block. In conducting this test, the anesthetist is reminded to keep the patient's foot straight up. If the patient is allowed to externally rotate the foot, he can accomplish adduction of the leg with the adductor magnus (in. nervated by the sciatic nerve), thus leading to a "false-negative" examina. tion. The sensory distribution of the obturator nerve is graphically illustrated in figure 3 and can be evaluated with a saturated alcohol sponge or needle point. Lumbar plexus block (Inguinal paravascular "3:1 block") In an attempt to decrease the number of injections and the time necessary to perform three separate nerve blocks, Winnie and coworkers, 8 6 in 1973, introduced a technique whereby all three major nerves of the lumbar plexus could be anesthetized with a single injection. Their technique is based on the fact that the lumbar plexus forms in front of the quadratus lumborum mus- June/1978 cle and behind the psoas major muscle. (See figure 1.) Therefore, the three major nerves are sandwiched between these muscles and thus are invested by their fasciae. As the femoral nerve emerges from the plexus, it descends in a groove formed between the psoas major and iliacus muscles. The fasciae of these muscles, along with the transversalis fascia, create a fascial compartment or "sheath" around this nerve which follows it down to the level of the inguinal ligament. Below the ligament, the fused ilio-psoas fascia, the fascia lata, and the thick ilio-pectineal fascia complete this sheath, which eventually fuses into the muscles of the anterior thigh. (See figure 7.) Since this fascial compartment is continuous from the thigh to the lumbar vertebrae, the authors theorized that injection of an anesthetic agent anywhere along its course would result in block. As with other "sheath" techniques, 87-89 the level at which the injection is made and the volume of anesthetic agent injected will affect the distribution of the block. The technique they subsequently introduced has become known as the "inguinal paravascular" lumbar plexus block. Isolation of the femoral nerve, as described previously, is carried out. With the needle remaining in place or advanced slightly cephalad, the index finger is used to hold firm pressure distal to the site of injection. This is done to prevent retrograde flow and to promote cephalad flow of the agent as it is injected. Some 20-25 cc of agent (1/ pt. height in inches) is injected, and the needle is removed. Digital pressure is maintained and the area is massaged in a cephalad direction to promote flow up the sheath. Figure 13 illustrates the distribution obtained with the injection of 20 cc. From this, it can be seen that the agent will spread up to the level of the lumbar plexus, thereby blocking the three major nerves-the lateral femoral 249 Figure 13. An x-ray taken immediately following the injection of 20 cc of an anesthetic agent with contrast material into the fascial compartment surrounding the femoral nerve by the "inguinal paravascular technique." 36 Note that the bulk of solution flows cephalad to the level of L-4, thus blocking the components of the lumbar plexus which innervate the lower extremity. (Reprinted with permission from the article by Alon P. Winnie, MD, et al, "The Inguinal Paravascular Technqiue of Lumbar Plexus Anesthesia," Anesthesia and Analgesia, Vol. 52, Nov-Dec, 1973.) cutaneous, the obturator, and, of course, the femoral. On occasion, in exceptionally tall patients, the lateral femoral cutaneous nerve may be missed, as it is the first nerve to leave the plexus and may not be exposed to the agent. This can be blocked separately or by simply increasing the volume of the agent used. The authors of this technique88 state that at least three of the potential risks associated with separate nerve block can be avoided. These risks are intravascular injection, trauma to the nerve from multiple needle exploration, and systemic toxic reactions secondary to an overdose of the anesthetic agent. Lumbar plexus block (Psoas sheath block) It was noted earlier that the lumbar plexus forms within the substance of the psoas major muscle. This muscle arises from the inferior borders of the transverse process of the lumbar vertebrae and the lateral aspects of the lumbar vertebrae and intervertebral discs. As this muscle is enclosed by a tough membranous fascia ("sheath"), injection of local anesthesia agents will provide block of the entire lumbar plexus. 40 With the patient in the lateral position and with the side to be blocked uppermost and the legs flexed into a "fetal" position, the spinous process of the third lumbar (L3) vertebrae is identified. A skin wheal of local anesthesia is made approximately 3-cm lateral to this spine, on the side to be blocked. A 3/ 2 -inch 20-gauge (spinal) needle is placed through the skin wheal, directed approximately 15-20° in a cephalad direction, and advanced until the transverse process (L3) is encountered. As the psoas muscle, which is 2-4 cm thick at this point, lies anterior to the transverse process, the needle is withdrawn, redirected slightly caudad, and advanced an additional .5-1 cm so as to enter the sheath of the psoas muscle. This needle technique is graphically illustrated in figure 14. Paresthesias to the anterior leg are occasionally noted by some patients but are not considered essential to the performance of the technique. A syringe is then attached to the needle and aspirated to obviate intravascular injection; 30 cc of the desired anesthetic agent are injected. This volume will inject easily with the patient frequently demonstrating a sensation of pressure in his flank radiating to his hip. Figure 15 demonstrates the distribution of 30 cc of an anesthetic agent to which contrast medium has been added. The outline of the psoas muscle is well defined. Onset of block is generally rapid Journalof the American Association of Nurse Anesthetists Figure 14. When performing the "psoas sheath block," 4 0 the needle is introduced so as to encounter the transverse process of L-3. The needle is then withdrawn and redirected so as to pass slightly caudad to the transverse process and is advanced an additional .5-1 cm into the sheath of the psoas muscle where injection of 30 cc of anesthetic agent is made. with sympathectomy (vasodilation and increased skin warmth) of the upper leg being the first subjective signs noted. Motor function tests, as described for the individual nerve blocks, will provide a more reliable index of onset and completeness. Sensory anesthesia will include the areas innervated by the lateral femoral cutaneous, the femoral and the obturator nerves-namely the lateral, anterior, and medial thigh and the medial aspect of the lower leg down to the medial malleolus. As the posterior thigh, posterior and lateral calf and foot are innervated by the sciatic nerve, separate block of this important nerve combined with the psoas sheath block will provide complete anesthesia of the lower extremity. spinal nerves and the first three sacral nerves. These roots converge towards the greater sciatic foramen to form the sciatic nerve. (See figure 16.) The plexus lies on the posterior wall of the pelvis between the piriformis and hypogastric muscles. The sciatic nerve, a continuation of the sacral plexus, is the largest nerve in the body and is formed by the combination of two separate nerves, the common peroneal and tibial, contained within one sheath. The nerve appears as a wide, flattened band measuring approximately .3-.5 cm in thickness and 1.5-2 cm in width as it leaves the pelvis. The nerve trunk leaves the pelvis through the greater sciatic foramen between the piriformis muscles and descends in a groove between the iscial tuberosity and greater trochanter of the Sacral plexus The sacral plexus is formed by the roots of the fourth and fifth lumbar femur. June/1978 At various points along its course, the sciatic nerve gives off several ar- Figure 15. An x-ray made following the injection of 30 cc of anesthetic agent with contrast media via the "psoas sheath" technique 40 as described in the text. This technique places the agent within the sheath of the psoas major muscle, thus blocking the components of the lumbar plexus (lateral femoral cutaneous, femoral, and obturator nerves). Note the outline of the psoas major muscle and slight extravication of media outside the psoas fascia made during withdrawal of the needle prior to completion of injection. ticular and muscular branches. The articular branches arise from the upper part of the nerve and supply the hip joint. The short head of the biceps femoris is supplied by a branch from the common peroneal portion, while the tibial portion gives rise to the muscular branches innervating the semitendinous semimembranous and adductor magnus. Sciatic nerve block (Classic technique) It was noted earlier that the sciatic nerve is found in a groove between the iscial tuberosity and the greater tro- chanter of the femur. These boney landmarks form the basis of the classic or "posterior" approach for blocking the sciatic nerve. At this point, the nerve is located posterior to the ischium, the obturator internus and gemelli, and quadratus femoris muscles and is located anterior to the gluteus maximus. The patient is placed in the lateral (Simms) position with the leg to be blocked uppermost, with both legs flexed as much as possible. A skin mark is made from the greater trochanter of the femur to the posterior superior iliac spine. At the mid-point of this line, a perpendicular line is drawn inferiorly and medially for approximately 3 cm (See figure 17.) At this point, a skin wheal of local anesthesia is made, and a 3 -inch 20gauge (spinal) needle is placed through the skin perpendicular to all skin planes. One lead of a peripheral nerve stimulator is attached to the hub of the needle, and the other lead is attached to a disposable ECG pad placed elsewhere on the patient's body. (See figure 18.) The stimulator's output is placed on the desired setting and the frequency is set at 1 stimulation per second. The needle is slowly advanced until maximal stimulation (contraction) of the muscles innervated by the sciatic nerve, in particular the extensors of the foot, are noted. (See figure 11.) Paresthesia radiating to the foot may be elicited during this maneuver but is not considered essential when utilizing this technique. A 10-cc syringe, filled with the desired anesthetic agent(s), is attached and aspirated to obviate intravascular injection. A test dose of 1-2 cc is injected and the foot is observed for "fade" as described elsewhere in this paper. Upon demonstration of this indicator, the remainder of the agent is injected and the needle is withdrawn. Onset of block, depending on the agent and concentration used, will be noted in 3-5 minutes with surgical anesthesia being present in 15-20 minutes. As prolonged involuntary move- Journalof the American Association of Nurse Anesthetists Figure 16. Origin of the sacral plexus and sciatic nerve. (Reprinted with permission from the book, Principles of Anesthesia, by Vincent J. Collins, MD, Lea and Febiger Publisher, Philadelphia, Pa., 1976.) Figure 17. The classic (Labat's) technique of sciatic nerve block: a line is drawn from the greater trochanter of the femur to the posterior superior iliac spine. A second line is dropped perpendicular at its midpoint. A skin wheal and insertion of the probing needle are made approximately 3 cm down this line. Greater i trochonter S for sciatic n. Rint of injection Post. sup. iliac spine / (Reprinted with permission from the article by Alon P. Winnie, MD, "Plexus Block for Lower Extremity Surgery," Anesthesiology Review, Vol. 1, 1974.) June/1978 Figure 18. Author's technique for sciatic nerve block. Note the classic landmarks and use of the electronic nerve stimulator to isolate the nerve. Journal of the American Association of Nurse Anesthetists Figure 20. As the sciatic nerve provides motor innervation to the extensors of the leg and foot, the patient's inability to (A) extend the lower leg or (B) extend the foot against resistance is taken as evidence of ensuing block. 20-A 20-B June/1978 ment of the lower extremity may cause unnecessary discomfort for the patient, the anesthetist is reminded to discontinue the stimulator as soon as the sciatic nerve is located and resume it for only a short time to demonstrate the test-dose/fade sequence. The sensory innervation of the sciatic nerve is graphically illustrated in figure 19 and easily can be tested with an alcohol sponge or pin point. The onset of diminished motor function provides a more objective indicator of block onset and completeness. As the sciatic nerve provides motor innervation of the flexors of the lower leg, the patient's diminished ability to flex his leg against resistance is considered indicative of impending block. The sciatic nerve additionally innervates the extensors of the foot. Therefore, the patient's decreased ability to extend the lower leg (figure 20A) or foot (figure 20B) against resistance is considered a favorable sign of ensuing block. Sciatic nerve block (Alternate methods) Occasionally, it is impossible or unduly painful to place the patient in the lateral position. As a result, several alternate approaches to the sciatic nerve have been described, including the anterior approach by Beck, 41 the lateral approach by Molesworth 42 or Ichiya. nagi, 48 and a posterior approach with the patient in the supine position by Winnie. 44 It is beyond the scope of this article to attempt to present these techniques in detail. The reader is encouraged to consult the original works of these authors to learn the specifics of their techniques. Combined lumbosacral plexus block In 1974, Winnie and coworkers 44 introduced a technique by which both the lumbar and sacral plexus could be anesthetized with a single injection. Figure 21. Anatomical landmarks described by Winnie et al44 for performing the "combined lumbosacral plexus block." See text for details of this technique. Ili ac c re s t Pbst sup. iliac spine . Spinous process (Reprinted with permission from the article by Alon P. Winnie, MD, "Plexus Block for Lower Extremity Surgery," Anesthesiology Review, Vol. 1, 1974.) 256 Journal of the American Association of Nurse Anesthetists This is possible as both the plexus are sandwiched between the quadratus lumborum and psoas major muscle and thus are enclosed by the fasciae of these muscles. The concept then is to inject a volume of drug into this space which is adequate to spread caudad and cephalad sufficiently to be exposed to both plexus. Their work suggests that 40 cc is an appropriate volume. The patient is placed in the lateral (Simms) position with the leg to be blocked uppermost and the knees flexed towards the chest. A skin line is drawn between the iliac crests. This line will pass through the L 4-5 vertebral interspace. Figure 22. An x-ray taken following the injection of 30 cc of an anesthetic agent and contrast media via the technique of "lumbosacral plexus block" as described in the text. This technique places the agent in the fascial space between the psoas major muscle (anterior) and the quadratus lumborum and iliacus muscles (posterior), thus blocking both the lumbar and sacral plexus. A second line is made, on the side to be blocked, parallel to the spine through the posterior superior iliac spine (figure 21.) A skin wheal of local anesthesia is made at the intersection of these lines. A 31/2-inch 20-gauge (spinal) needle is placed through the skin wheal and is advanced slowly in a mesiad direction until the transverse process of L-4 is encountered. The needle is withdrawn to the subcutaneous tissues and redirected slightly caudad. It is then advanced (approximately 5-6 cm) until a paresthesia radiating to the leg is obtained. On occasion, the use of a nerve stimulator, as described earlier, has elicited good results. When the nerve plexus is isolated, 40-cc of the desired anesthetic agent is injected. Figure 22 illustrates the spread of this volume within the "lumbosacral sheath." The patient is then placed in the supine position; and evaluation of motor function, as previously described, is carried out. Depending on the agent and its concentration, motor loss will be evident in 3-5 minutes, with surgical anesthesia complete in 15-20 minutes. DeKrey 4 0 and Chayen 45 have described similar single injection lumbosacral plexus techniques. The reader is encouraged to consult their original works for specifics of their techniques. Discussion It is acknowledged that the clinician cannot master the skills of conduction anesthesia simply from published materials. Indeed, the reader is advised against unsupervised attempts at these techniques. The purpose then, of this and a companion article 46 in the June, 1977 issue of the AANA Journal has been to chronicle the historical, anatomical, and technical developments which have lead to the descriptions of various techniques for providing conduction anesthesia of the human extremities. In addition, the author's modifications of some techniques have been described. June/1978 REFERENCES (1) Little, David M. Jr., 1972. Classical File, Survey of Anesthesiology. 16:278. (2) Ibid, 279. (3) Lundy, J. S. 1942. Clinical Anesthesia, W. B. Saunders Co., Philadelphia, Pa. p. 707. (4) Bartholow, R. 1873. Manual of Hypodermic Medication, 2nd Edition, Philadelphia, Pa., J. B. Lippincott Co. (5) Wood, A. 1855. New Method of Treating Neuralgia by the Direct Application of Opiates to the Painful Parts, Edinburgh M.&S. Quart. J. 82:265. (6) Braun, H. 1914. Local Anesthesia, Lea and Febiger, Philadelphia, Pa. (7) Koller, C. 1884. The Use of Local Anesthesia on the Eye. Preliminary Report. Rostock, Universitiits-Buchdruckereivon Adler's Erben, pp 60-63, Translation in Foundations of Anesthesiology by Faulconer and Keys, pp 773-775, Volume 2. (8) Burke, W. C. Jr. 1884. Hydrochlorate of Cocaine in Minor Surgery, New York Medical Journal, 40:616-617 (Nov. 29). (9) Halstead, W. S. 1885. Practical Comments on the Use and Abuse of Cocaine; Suggested by Its Invariably Successful Employment in More Than A Thousand Minor Surgical Operations, New York Medical Journal, 42:294-295 (Sept. 12). (10) Schleich, K. L. 1895. A New Method of Local Anaesthesia (Infiltration Anaesthesia), International Clinics (5th series), 2:177-192 (July). (11) Braun, H. 1903. The Addition of Epinephrine to Cocaine for Local Anesthesia Archiv fur klinische Chirurgie 69:541-591, Translated in Foundations of Anesthesiology by Faulconer and Keys, Volume 2, pp 834-842. (12) Einhorn, A. 1899. On the Chemistry of Local Anesthetics, Muncher medicinische Wochenschrift, 46:1218-1220 (Sept. 12), Translated in Faulconer and Keys, pp 801-807. (13) Braun, H. 1905. Several New Local Anesthetic Agents, Deutsche medizinishe Wochenschrift, 2:1667-1671 (Oct. 19), Translated in Faulconer and Keys, pp 842-847. (14) Bier, A. K. G. 1899. Experiments in Cocainization of the Spinal Cord. Deutsche Zeitschcift fur Chirurgie, 51:361-369 (April), Translated in Faulconer and Keys, pp 850-858. (15) Sicard, J. A. 1901. The Extradural Injection of Agents by the Sacrococcygeal Route, Comptes rendus hebdomadaires des seances et memoires de la Societe, 53:396-398 (April 20), Translated in Faulconer and Keys, pp 921-923. (16) Pages, F. 1921. Metameric Anesthesia, Rirista de la sanidad militar, Madrid, s.3, 11: 351-365, pp 385-396. Translated in Faulconer and Keys, pp 927-945. (17) Southworth, J. L.; Hingson, R. A. (eds). 1953. Pitkin's Conduction Anesthesia, J. B. Lippincott Co., Philadelphia, Pa. (18) Labat, G. 1923. Regional Anesthesia, Its 258 Technic and Clinical Application, Second Edition, W. B. Saunders Co., Philadelphia, Pa. (19) Cray, H. 1973. Anatomy of the Human Body, 29th American edition, Edited by Charles Mayo Goss, Lea and Febiger, Philadelphia, Pa. (20) K.iser, R. A. 1949. Obturator neurectomy for anatomic study of obturator and accessory obturator nerves, Journalof Bone and Joint Surgery (31 (A) :815. (21) Labat, loc. cit. (22) Eriksson, E. 1969. Illustrated Handbook in Local Anesthesia, Year Book Publishers, Chicago, Ill. p. 102. (23) Bridenbaugh, I. D. 1963. Lower Extremity Nerve Blocks, International Anesthesia Clinics, 1:745-753. (24) Moore, D. C. 1965. Regional Block, 4th edition, Charles C. Thomas Co., Springfield, Ill. p. 295. (25) Pue, A. 1976. Disposable EKG Pads for Peripheral Nerve Stimulation, Anesthesiology, (Correspondence) 45(1) :107-108. (26) Liifstrom, B., Wennberg, A. & Widen, L. 1966. Late disturbances in nerve function after block with local anesthetic agents-An electroneurographic study. Acta anaesthesiologica Scandinavica, 10:111. (27) Sarnoff, S. J., Sarnoff, L. C. 1951. Prolonged peripheral nerve block by means of indwelling plastic catheter. Treatment of Hiccup (Note on the electrical localization of peripheral nerve), Anesthesiology, 12:270-275. (28) Pearson, R. B. 1955. Nerve Block in Rehabilitation: A Technic of Needle Local. ization, Archives of Physical Medicine and Rehabilitation, 36:631-633. (29) Greenblatt, G. M., Denson, J. S. 1962. Needle nerve stimulator-locator: nerve block with a new instrument for locating nerves, Anesthesia and Analgesia, 41:599-602. (30) Magora, E., Rozin, R., Ben-Menachem, Y., et al. 1969. Obturator nerve block-an evaluation of technique, British Journal of Anaesthesia, 41:695-698. (31) Wright, B. D. 1969. A new use for the Block-Aid Monitor,® Anesthesiology, 30:236237. (32) Koons, R. A. 1969. The use of the Block-Aid Monitor,® and plastic intravenous cannulas for nerve blocks, Anesthesiology, 31:290-291. (33) Chapman, G. M. 1972. Regional nerve block with the aid of a nerve stimulator, Anaesthesia, 27(2) :185-193. (34) Montgomery, M. B., et. al. 1973. The use of the nerve stimulator with standard unsheathed needles in nerve blockade, Anesthesia and Analgesia, 52(5):827-831. (35) Perthes von, G. 1912. Uker leitung. saniisthesie unter zuhilfenahme elektrischer reiqung, Med WVschr, 47:2545-2548. (36) Winnie, A. P., Ramamurthy, D. Z. 1973. The Inguinal Paravascular Technique of Lumbar Plexus Anesthesia: The "3-in-1 Block," Anesthesia and Analgesia, 52(6) :989-996. coxalgia; Journalof the American Association of Nurse Anesthetists (37) DeJong, R. H. 1961. Axillary Block of the Brachial Plexus Anesthesiology, 22:215. (38) Winnie, A. P., Collins, V. J. 1964. The Subclavian Perivascular Technique of Brachial Plexus Anesthesia, Anesthesiology, 25: 353-363. (39) Winnie, A. P., 1970. Interscalene Brachial Plexus Block, Anesthesia and Analgesia, 49:455-466. (40) DeKrey, J. A. 1973. Unpublished manuscript. Presented at the 47th Congress of the International Anesthesia Research Society, March 11-15, 1973, Bal Harbour, Fla. (41) Beck, G. P. 1963. Anterior Approach to Sciatic Nerve Block, Anesthesiology, 24(2) : 222-224. (42) Molesworth, H. W. L. 1944. Regional Analgesia, H. K. Lewis Co, London, Eng. p. 40. (43) Ichiyanagi, K. 1959. Sciatic Nerve Block: Lateral Approach with the Patient Supine, Anesthesiology, 20(5) :601-604. (44) Winnie, A. P., Ramamurthy, S., Durrani, Z., et. al. 1974. Plexus Block for Lower Extremity Surgery, Anesthesiology Review, 1:11-16. (45) Chayen, D., Nathan, H., Chayen, M. 1976. The Psoas Compartment Block, Anesthesiology, 45(1) :95-99. (46) Reese, C. A. 1977. "Conduction Anesthesia of the Upper Extremity-A Literature and Technique Review," AANA Journal, 45(3) :267-278. ADDITIONAL READING (1) Faulconer, Albert Jr. and Keys, Thomas E. 1965. Foundations of Anesthesiology Volume 2, Charles C. Thomas Co., Springfield, Ill. ACKNOWLEDGEMENT The author wishes to acknowledge the kind professional assistance given to him by Captain Clyde W. Jones, MC, USN, Chair. man, Department of Anesthesiology and Captain John A. DeKrey, MC, USNR, Assistant Chairman, Naval Regional Medical Center, San Diego, California. June/1978 AUTHOR Charles A. Reese, PhD, CRNA, earned his BS in Nursing from the University of Oklahoma, Norman, Oklahoma; his BS in Nursing Anesthesia from the George Wash. ington University, Washington, D.C.; his MBA in Health Services Management from National University, San Diego, California; and his PhD in Health Services Administration from California Pacific University, San Diego. Dr. Reese is presently a Lieutenant Commander in the U.S. Navy Nurse Corps and serves as Clinical Coordinator of the Navy Nurse Corps Anesthesia School at the Naval Regional Medical Center, Portsmouth, Va. This paper was prepared while Dr. Reese was Clinical Coordinator of the Nurse Corps Anesthesia School at the Naval Regional Medical Center, San Diego, California. This material, along with that which appeared in his earlier article, "Conduction Anesthesia of the Upper Extremity-A Literature and Technique Review" (AANA Journal, June, 1977, Vol. 45 pp. 267-278) are taken from Dr. Reese's presentation on "Conduction Anesthesia for the Extremities" which he gave at the 44th AANA Annual Meeting and Professional Sessions in August, 1977 in Hollywood, Florida. The author wishes to state that the opinions or assertions contained in this article are his private views and are not to be construed as official and or reflecting the views of the Department of Anesthesiology, Naval Regional Medical Center, San Diego; the Navy Nurse Corps; the Department of the Navy; or Department of Defense.