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Brown: Atlas of Regional Anesthesia, 3rd ed., Copyright © 2006 Saunders, An Imprint of Elsevier
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Chapter 11 – Lumbar Plexus Block



The inguinal perivascular block is based on the concept of injecting local anesthetic near the femoral nerve in an amount sufficient to track proximally along fascial planes to anesthetize the lumbar plexus. The three principal nerves of the lumbar plexus pass from the pelvis anteriorly: lateral femoral cutaneous, femoral, and obturator nerves. As illustrated in Figure 11-1 , the theory behind this block presumes that the local anesthetic tracks in the fascial plane between the iliacus and the psoas muscles to reach the region of the lumbar plexus roots.

Click to view full size figure

Figure 11-1  Lumbar plexus anatomy: proposed mechanism of proximal local anesthetic spread.

Patient Selection.

As outlined, lower extremity block is often most effectively and efficiently performed with neuraxial blocks. Nevertheless, in some patients avoidance of bilateral block and/or sympathectomy may make an alternative approach necessary.

Pharmacologic Choice.

Local anesthetics should be selected by deciding whether a primarily sensory block or a sensory and motor block is needed. Any of the amino amides can be used. It has been suggested that the volume of local anesthetic needed for adequate lumbar plexus block using this approach can be estimated by dividing the patient’s height, in inches, by 3. That number is the volume of local anesthetic in milliliters that theoretically provides a lumbar plexus block.



The concept behind the lumbar plexus block is that the only anatomy one needs to visualize is the extension of sheath-like fascial planes that surround the femoral nerve.


The patient should be placed supine on the operating table with the anesthesiologist standing at the patient’s side in position to palpate the ipsilateral femoral artery.

Needle Puncture.

A short-beveled, 22-gauge, 5-cm needle is inserted immediately lateral to the femoral artery, caudal to the inguinal ligament in the lower extremity to be blocked. It is advanced with cephalad angulation until a femoral paresthesia is obtained. At this point, the needle is firmly fixed, and while the distal femoral sheath is digitally compressed the entire volume of local anesthetic is injected.

Potential Problems.

My clinical experience suggests that the principal problem with this technique is a lack of predictability. Additionally, whenever a large volume of local anesthetic is injected through a fixed “immobile” needle, the risk of systemic toxicity is increased. If the technique is used, incremental injection of local anesthetic, accompanied by frequent aspiration for blood, should be performed.


My suggestion is to use this block when lower extremity analgesia is the goal rather than for anesthesia during an operation. I do not believe one needs to master this technique to provide comprehensive regional anesthesia care.

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