Ovid: Peripheral Nerve Blocks: A Color Atlas

Continuous Lumbar Plexus Blocks

A. Continuous Lumbar Plexus Block

Jacques E. Chelly

Patient Position: Lateral with the operative side up.

Indications: Anesthesia and immediate postoperative analgesia for major knee surgery, hip arthroplasty, femoral neck fracture surgery, and any surgery performed in the territory of the femoral and lateral cutaneous nerves.

Needle Size and Catheter: 18-gauge, 100-mm insulated Tuohy needle and 20-gauge catheter.

Volume and Infusion Rate: 30 mL 0.5% ropivacaine (anesthesia), 15 to 20 mL ropivacaine 0.2% followed by an infusion of 6 to 8 mL/hour 0.2% ropivacaine (postoperative analgesia).

Anatomic Landmarks: The superior border of the posterior iliac crest and the spinous process of L4-L5.

Approach and Technique: A vertical line is drawn at the level of the superior border of the posterior iliac crest. Next a horizontal line is drawn at the level of the spinous process of L5-L4. The site of introduction of the needle is 5 cm above the spinous processes on the bisiliac line. The needle, with the bevel oriented cephalad, is introduced perpendicular to the skin in the direction of the transverse process. The needle is then walked cephalad off the transverse process until a stimulation of the femoral nerve is elicited. The position of the needle is adjusted to produce a motor response with a current less than 0.5 mA (Fig. 28-1). After negative blood aspiration, local anesthetic solution is slowly injected. The injection is followed by the placement of a catheter introduced 3 to 5 cm beyond the needle tip. The catheter is secured and covered with a transparent dressing.

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Figure 28-1. The lumbar plexus is identified and the needle is advanced.

Tips

When combined with a sciatic nerve block, this block may provide surgical anesthesia to the lower extremity.
Epidural spread and/or injections may result in a bilateral block.
A loss-of-resistance technique can be used, especially when the block is performed for postoperative analgesia.

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A more medial approach has been described (3.5 cm from the spinous process).
Continuous lumbar plexus blocks should not be performed in anticoagulated patients, because of the risk of retroperitoneal hematoma.

Suggested Readings

Awad IT, Duggan EM. Posterior lumbar plexus block: Anatomy, approaches, and techniques. Reg Anesth Pain Med 2005;30:143–149.

Capdevila X, Coimbra C, Choquet O. Approaches to the lumbar plexus: success, risks and outcome. Reg Anesth Pain Med 2005;35:150–162.

Capdevila X, Macaire P, Dadure C, et al. Continuous psoas compartment block for postoperative analgesia after total hip arthroplasty: new landmarks, technical guidelines, and clinical evaluation. Anesth Analg 2002;94:1606–1613.

Chudinov A, Berkenstadt H, Salai M, et al. Continuous psoas compartment block for anesthesia and perioperative analgesia in patients with hip fractures. Reg Anesth Pain Med 1999;4:563–568.

Klein S, D'Ecole F, Greengrass R, et al. Enoxaparin associated with psoas hematoma and lumbar plexopathy after lumbar plexus block. Anesthesiology 1997;87:1576–1579.

Mansour NY, Bennetts FE. An observational study of combined continuous lumbar plexus and single-shot sciatic nerve blocks for post-knee surgery analgesia. Reg Anesth 1996;21:287–291.

Schultz P, Anker-Moller E, Dahl JB, et al. Postoperative pain treatment after open knee surgery: continuous lumbar plexus block with bupivacaine versus epidural morphine. Reg Anesth 1991;16:34–37.

White IW, Chappell WA. Anaesthesia for surgical correction of fractured femoral neck: a comparison of three techniques. Anaesthesia 1980;35:1107–1110.

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B. Continuous Femoral Nerve Block

Guido Fanelli

Patient Position: Supine.

Indications: Continuous femoral nerve block works well for postoperative analgesia in patients undergoing thigh and knee surgery. It does not completely cover an incision extending onto the tibia, but provides significant analgesia.

Needle Size and Catheter: 18-gauge, 50-mm insulated Tuohy needle and 20-gauge catheter.

Volume and Infusion Rate: 30 mL 0.5% ropivacaine, followed by an infusion of 7 to 12 mL/hour 0.2% ropivacaine.

Anatomic Landmarks: The same as for the single-injection technique (1 cm lateral from the femoral artery); however, the needle entry point is 2.5 cm below the inguinal ligament to allow a flatter needle trajectory.

Approach and Technique: The femoral artery is identified. The needle entry site is 2.5 cm below the inguinal ligament and 1 to 2 cm lateral to the femoral pulse. The needle is advanced cephalad at a 60° angle to the skin (Fig. 28-2). In almost all cases, two distinct pops are felt as the needle passes through thick fascial planes. The needle is correctly placed when patellar ascension is noted. The local anesthetic solution is slowly injected after negative blood aspiration. The catheter is then threaded 3 to 5 cm beyond the needle tip. The Tuohy needle is removed, and the catheter is secured with Steri-Strip and covered with a transparent dressing.

Tips

If the medial thigh is twitching, direct the needle more laterally and at a shallower angle.

Figure 28-2. The femoral artery is identified and the needle is advanced.

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If the catheter does not thread easily, drop the angle of the needle so it is at a less acute angle.
Placing the stimulator under a clear drape allows one person to run the stimulator and drive the needle at the same time.

Suggested Readings

Capdevila X, Barthelet Y, Biboulet P, et al. Effects of perioperative analgesic technique on the surgical outcome and duration of rehabilitation after minor knee surgery. Anesthesiology 1999;91:8–15.

Chelly JE, Gebhard R, Coupe K, et al. Local anesthetic PCA via a femoral catheter for the postoperative pain control of an ACL performed as an outpatient procedure. Am J Anesthesiology 2001;28:192–194.

Chelly JE, Greger J, Gebhard R, et al. Continuous femoral blocks improve recovery and outcome of patients undergoing total knee replacement. J Arthroplasty 2001;16:436–446.

Ganapathy S, Wasserman RA, Watson JT, et al. Modified continuous femoral three-in-one block for postoperative pain after total knee arthroplasty. Anesth Analg 1999;89:1197–1202.

Singelyn FJ, Deyaert M, Joris D, et al. Effects of intravenous patient-controlled analgesia with morphine, continuous epidural analgesia, and continuous three-in-one block on postoperative pain and knee rehabilitation after unilateral total knee arthroplasty. Anesth Analg 1998;87:88–92.

Singelyn FJ, Gouverneur JM. Extended “three-in-one” block after total knee arthroplasty: continuous versus patient-controlled techniques. Anesth Analg 2000;91:176–180.

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C. Continuous Fascia Iliaca Block

Louis-Jean Dupre

Patient Position: Supine, with operative leg extended and slightly abducted.

Needle Size and Catheter: 18-gauge Tuohy needle and 20-gauge catheter.

Volume and Infusion Rate: 20 to 25 mL 0.5% ropivacaine followed by an infusion at a rate of 8 to 10 mL/hour 0.2% ropivacaine.

Anatomic Landmarks: The psoas muscle surrounded by the fascia iliaca and its extensions, the femoral, lateral cutaneous, and obturator nerves, which run immediately under the fascia iliaca. When the local anesthetic is injected under the fascia, the diffusion can theoretically reach the three nerves (Fig. 28-3). The anterosuperior iliac spine and the pubic symphysis (inguinal ligament), the femoral artery, and the sartorius muscle are also landmarks.

Approach and Technique: A line between the anterosuperior iliac spine and pubic symphysis is drawn, demarcating the inguinal ligament. Femoral pulse and the medial border of the sartorius muscle are palpated, and the femoral artery is marked. The puncture point is situated 2 to 3 cm below the inguinal ligament, just distal to the inguinal crease, and 2 to 3 cm lateral to the femoral artery. The 18-gauge Tuohy needle is introduced through the skin at a 30° angle. A two-pop loss of resistance perception is felt, corresponding

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to the crossing of the fascia lata and the fascia iliaca, respectively. After negative aspiration for blood, 20 mL of local anesthetic is slowly injected (Fig. 28-4). This is followed by the introduction of a 20-gauge catheter 3 to 5 cm beyond the needle tip (8 to 12 cm at the skin). The Tuohy needle is removed, and the catheter is secured with Steri-Strip and covered with a transparent dressing.

Figure 28-3. Three nerves are identified.

Figure 28-4. Local anesthetic is slowly injected.

The intensity of the sensory block of the lateral femoral cutaneous nerve is evaluated on the lateral aspect of the thigh. The intensity of the sensory block of the femoral nerve is tested on the anterior aspect of the thigh and the medial aspect of the leg (saphenous nerve). The intensity of the femoral motor block is evaluated through the extension of the leg. Testing the obturator nerve block is particularly difficult because the sensory territory of the obturator nerve at the knee is inconsistent and frequently absent, and because the adduction of the lower limb is only 60% dependent on the obturator nerve.

Tips

The lateral part of the fascia iliaca is a very thick aponeurosis closing the muscular compartment, while the medial part is a thin perforated aponeurosis. Therefore, a lateral approach provides a better sensation of the crossing of the fascia. This is also facilitated by the use of a large-gauge needle with a dull tip or with a short bevel.
This block can also be performed with an 18-gauge, 50-mm plastic introducer cannula with a stylet with a 30° bevel. Once the skin is pierced, the needle is rotated and redirected cephalad at a 30° angle to the thigh. This slope means the bevel is parallel to the fascia, thus making penetration more difficult but easier to recognize.
A complete block of the femoral and lateral femoral cutaneous nerves requires time. This approach often produces an incomplete obturator block.
The success rate for the iliofascial block is greatly dependent on operator experience.
With obese patients, it is sometimes necessary to have an assistant hold back the abdominal skin to facilitate recognition of the crossing of the fascia.
Intravascular injection is possible in the small caliber circumflex veins that run under the fascia lateral to the femoral artery. Careful aspiration is necessary before injection.

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Postoperative falls by the patient are the major risk with this technique, due to the absence of knee locking. An extension splint is required if the patient is allowed to get up before recovery from the block.