Lower PB Flashcards
What are risks of peripheral nerve blocks?
- LA toxicity
- allergic response
- perm/transient nerve damage
- uncomfortable pt positioning
- incomplete blocks
What are the two classes of LA’s? How are they metabolized?
- esters: metabolized by plasma, higher potential for allergic reaction
- amides: metabolized by liver
Name sites in order of max to min rate of absorption.
- Intercostals
- Caudal
- Epidural
- Brachial plexus
- Sciatic
- Lumbar plexus
- Femoral
What can systemic absorption lead to?
- CNS toxicity
- Cardiac toxicity
What does epinephrine do to LA? What does it allow?
- It prolongs anesthesia
- allows low concentrations of LA in a large volume
- used as alternative or with anesthesia
What are s/s of CNS toxicity from LA toxicity? What are other effects?
- tongue numbness
- lightheaded/dizzy
- tinnitus
- disoriented
- visual disturbances
- seizures
- lead to CNS depression, resp depression/arrest
- CV instability
How can you prevent LA toxicity?
- vigilant monitoring
- limit dose
- aspirate before each injection of 5 ml at a time
What is nerve localization and how do you perform it?
- anatomic relationship of nerves to muscles, bones, arteries
- cause paresthesias via nerve stimulator technique
- or ultrasound guided
What nerves does the sciatic nerve block include?
-L4-S3: ventral branches of LS trunk
What structures does the sciatic nerve block anesthetize?
- foot, lower extremity distal to knee and posterior leg
- sciatic n, fibular n, peroneal n
usually combined with fem or popliteal block for achile’s tendon surgery
What are the landmarks for a sciatic nerve block?
- draw line 1 from greater trochanter to post/sup iliac spine and bisect it over the gluteal muscle
- draw line 2 from greater trochanter to sacral hiatus
- point where line 2 intersects with bisect line is injection site
What twitch will occur with common peroneal nerve of sciatic block? What does this indicate?
- dorsiflexion or eversion of foot
- more lateral
- “P.E.D”
What twitch will occur with tibial nerve block of sciatic block?
- plantar flexion of foot and toes
- more medial
- “T.I.P”
What are complications of a sciatic nerve block?
- block failure
- hematoma
What is the largest branch of the lumbar plexus?
Femoral nerve
What is the course of the femoral nerve?
-thru psoas into groove between psoas and iliacus and under inguinal ligament supplying several branches to anterior thigh, knee, and hip
What does the femoral nerve block anesthetize?
What motor function does it eliminate?
What does it do for postop pain?
- anterior thigh, knee, medial foot (small part)
- inability to abduct leg or extend lower leg
- excellent adjunct for postop pain relief
What are the landmarks for femoral n block?
- inuguinal ligament
- femoral “NAVEL”
- adductor longus
- lateral to fem artery and inferior to inguinal ligament
What are complications of femoral block?
- IV injection
- hematoma
- direct nerve injury
What is the indication for a popliteal nerve block?
-foot and ankle surgery
What are the landmarks for popliteal nerve block?
- popliteal fossa crease
- biceps femoris tendon
- semitendinosus and semimembranosus muscles
- inject 7 cm above crease
What is the twitch response for popliteal bock?
foot or toe twitch
What is an ankle block used for?
below ankle procedures
How do you detect location for ankle block placement?
- is a field block
- no nerve stimulator
