Lower Extremity Peripheral Nerve Block R4 장 지 혜

1. Lower Extremity Peripheral Nerve Block R4 장 지 혜

2. Lower Extremity Peripheral Nerve Block • Lower Extremity Peripheral Nerve Block Techniques • Psoas compartment block • Femoral nerve block • Lat. Femoral cutaneous nerve block • Saphenous nerve block • Parasacral block • Sciatic nerve block • Ankle and foot block • Pharmacologic Consideration • Complications of Lower Extremity Peripheral Nerve Blocks

3. Sensory Supply Areas of the Lumbosacral Plexus

4. Psoas Compartment Block(Lumbar plexus block) • Anesthesia for thigh surgery, and hip fracture repair in combination with a para sacral nerve block • Analgesia following THA, TKA and in the treatment of chronic hip pain. • Consistent anesthesia in the distributions of the femoral, lat.cutaneous n. of the thigh, and the obturator nn.

5. Psoas Compartment Block(Lumbar plexus block)

6. Femoral Nerve Block • Anesthesia for knee arthroscopy in combination with intra-articular local anesthesia • Analgesia for femoral shaft fractures, ant. cruciate lig. reconstruction(ACL), and TKA in multimodal regimens. • 3-in-1 block (femoral, LFC, obturator n.)

7. Femoral Nerve Block

8. Lateral Femoral Cutaneous Nerve Block • Anesthesia during diagnostic muscle biopsy and harvesting of split thickness skin grafts. • Blind “fan” technique with a variable success rate.

9. Saphenous Nerve Block • Supplies the cutaneous area of the medial aspect of the calf and foot to the level of the midfoot.

10. Parasacral Block (PSNB) • It has been used to provide analgesia following major foot and ankle reconstruction. • Consistently block both components of the sciatic nerve and the post. cutaneous nerve of the thigh. • The sympathetic n. supply to the bladder is also in close promixity but problems with voiding and the need for bladder catheterization after PSNB have not been reported.

11. Sciatic Nerve Block: At the level of the Gluteus Maximus

12. Subgluteal Approaches to the Sciatic Nerve • Supine approach to the sciatic nerve in the flexed hip position initiating the block at the midpoint between the greater trochanter of the femur and the ischial tuberosity. • Identifying bony landmarks in very obese patients is sometimes difficult and the patient position requires additional personnel to maintain.

13. Sciatic Nerve Block at the level of the Popliteal Fossa

14. Ankle and Foot Block

15. Pharmacologic Considerations • Complete unilat. blockade involves multiple nerve blocks and a larger volume of local anesthetic solution. • Attention must be given to total local anesthetic dose. • The concentration must also take into account the degree of sensory and/or motor block desired.

16. Epinephrine • Epi. prolongs the duration and quality of most local anesthetics used for lower extremity peripheral block. • Vasoconstriction of the perineural vessels • Decreases uptake and increases the neural exposure to the local anesthetics • Lidocaine vs Ropivacaine • The decision to add Epi. and the dose of Epi. • Cardiac or neural ischemia vs the ability to discern an intravascular injection

17. Epinephrine • The nearly equivalent effects on block quality and duration reported with Epi. 2.5 vs 5.0.㎍/ml, suggest that the lower concentration is sufficient.

18. Bicarbonate • There was little reason to add sodium bicarbonate with plain local anesthetics or those with freshly added epinephrine. • No difference in the onset or duration of combined lumbar plexus-sciatic block in pts. that received 0.5% bupivacaine with alkalinization compared to those who received a non-alkalinized solution.

19. Complications of Lower Extremity Peripheral Nerve Blocks • Serious Cx. following 21,278 PNBs in a 5-month period By Auroy et al. France • Per 10,000 PNBs, • 0-2.6 death, 0.3-4.1 cardiac arrests, 0.5-4.8 neurologic injuries, and 3.9-11.2 seizures • There is a paucity of reports of complications specifically associated with lower extremity PNBs compared to upper extremity PNBs. • Less common application rather than to inherent safety of the techniques.

20. Local Anesthetic Systemic ToxicityComplications of Lower Extremity Peripheral Nerve Blocks • The apparent margin of safety seems to vary with individual block techniques. • The difference in the anatomy, primarily in the vascularity and presence of deep muscle beds in the area of blockade • The severe toxic reactions typically occur during the injection or immediately upon the injection. • An unintentional intravascular injection of local anesthetic into the circulation, rather than absorption. • A forceful, rapid injection of local anesthetic carries a much higher risk of local anesthetic toxicity than a slow, gentle injection.

21. Local Anesthetic Systemic ToxicityComplications of Lower Extremity Peripheral Nerve Blocks • Prevention • Use of Epi. as an intravascular marker • Slow, methodical injection while avoiding high-injection pressure • Frequent aspiration • Constant assessment of the pts. and vital signs • Prudent selection of local anesthetic concentration and volume

22. Proximal Spread (Neuraxial Block)Complications of Lower Extremity Peripheral Nerve Blocks • Intrafascicular spread of the local anesthetic proximally toward the spinal cord, resulting in central neuronal blockade. • Needle placement at the level of the nerve roots or spinal nerves • Forceful, fast injections under high pressure into dural cuffs or perineurium • Post. approach to the lumbar plexus have the highest incidence of complications of the lower extremity PNBs.

23. Hemorrhagic ComplicationsComplications of Lower Extremity Peripheral Nerve Blocks • Several approaches for PNBs of lower extremity. • Psoas compartment approach to the lumbar plexus, the obturator nerve block, parasacral and classical approaches to the sciatic n. • This block is less suitable in the setting of anticoagulation as compared to other, more supf. lower extremity nerve blocks.

24. Infectious ComplicationsComplications of Lower Extremity Peripheral Nerve Blocks • The incidence of bacterial complications associated with the use of continuous femoral nerve blocks.By Cuvillon et al. • In their cohort of 208 pts, 57% had positive bacterial colonization of the catheter at 48 hrs. postoperatively. • There were no long-term sequelae related to these positive catheter cultures.

25. Neurologic ComplicationsComplications of Lower Extremity Peripheral Nerve Blocks • 0.4-18% of all nerve block procedures. • The symptoms of nerve injury after PNB usually manifest shortly after block resolution. • Intraneural injection is a well-known mechansm of neurologic injury associated with PNBs. • There is no consensus on the techniques or methods that can reduce the risk of intraneural injection. • Methods of nerve localization (i.e., paresthesia vs. nerve stimulation) • The advantages of short-bevel over sharper, long-bevel needles remain controversial.

26. Neurologic ComplicationsComplications of Lower Extremity Peripheral Nerve Blocks • Lancinating pain and high injection pr. may portend intraneural injection of local anesthetic, thus increasing the potential for n. injury. • Pain is not a reliable warning sign of impending nerve injury. • High injection pr.(>20 psi) with intraneural needle placement lead to nerve injury • Clinical perception of an abnormally high resistance and pressure required to inject is impossible to verify.

27. Neurologic ComplicationsComplications of Lower Extremity Peripheral Nerve Blocks • Neuronal ischemia can occur from a variety of sources. • Disruption of the neuronal microvasculature • High-endoneurial pressures • Addition of vasoconstricting agents • Exogenous compression from tourniquets • The potential for neurotoxicity with a local anesthetics • Function of its potency, concentration, the length of exposure of the neuronal tissue to the agent.

28. Neurologic ComplicationsComplications of Lower Extremity Peripheral Nerve Blocks • Local anesthetics are used in concentrations that, under normal clinical conditions, do not cause irreversible nerve damage. • Exposure of the endoneurium to high concentration of local anesthetics • While neurologic Cx. of PNBs are uncommon, they can and do occur even in the hands of experienced practitioners and may result in significant pts. suffering, distress to the practitioner, and medico-legal consequences.

29. Summary • Recent developments in the field of regional anesthesia have lead to an increased interest in lower extremity PNBs. • Transient neurologic symptoms associated with spinal anesthesia • Increased risk of epidural hematoma with the introduction of new anti-thromboembolic prophylaxis regimens • Evidence of improved rehabilitation outcome with continuous lower extremity PNBs. • Standardized and reproducible practice with more clearly defined indications - both to improve their clinical utility and to reduce the risk of complications.

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