Regional anesthesia Flashcards
Upper and lower extremity blocks
What particular part of the brachial plexus is targeted by the supraclavicular block?
The trunks/divisions appear as a cluster of grapes (hypoechoic circles) lateral the the pulsating subclavian artery and superior to the first rib.
Why is the supraclavicular block not indicated for shoulder surgery?
This block does not supply complete coverage because the suprascapular nerve which arises from the upper trunk (C5-C6) is often missed.
Why is the ultrasound used during the supraclavicular block?
When performing this block, the needle is in very close proximity to the pleura and the subclavian artery.
The supraclavicular block is appropriate for what types of surgical procedures?
The supraclavicular block provides analgesia for surgical procedures of the upper arm, elbow, wrist and hand
When using the landmark technique and nerve stimulator to perform a supraclavicular block, what is an acceptable twitch?
Finger twitch - flexion and extension
Unacceptable responses include: pectoralis (direct stim), biceps (musculocutaneous nerve) and deltoid (axillary nerve)
What are the signs of Horner’s syndrome
Ptosis, miosis, anhidrosis. These symptoms are due to the proximity of the supraclavicular block to the stellate ganglion.
How can the ultrasound be used to assess the status of pleura if a pneumothorax is suspected?
If lung sliding is present, the pleura is intact. If you do not see lung sliding, the patient may have a pneumothorax. A CXR should be used to rule this out. Symptoms may include cough, chest pain, and dyspnea (late sign) after the block.
During a subclavian block, how often can the patient experience phrenic paralysis or Horner’s syndrome?
About 50% of the time! Watch for signs of ptosis, miosis and anhidrosis.
What part of the brachial plexus is targeted during an infraclavicular block?
The cords. Blocking the brachial plexus at the level of the cords is a good alternative to the supraclavicular block in patients with respiratory insufficiency d/t the decreased risk of phrenic nerve blockade
What are the 3 most common errors that occur and increase the risk of pneumothorax during an infraclavicular block?
- needle insertion too medial
- directing the needle medially
- inserting the needle too deep (>6cm)
When the median nerve is stimulated, what is the correct muscle response to stimulation?
Flexion of the first 3 1/2 digits and opposition of the thumb
When stimulating the radial nerve, what is the correct response to stimulation?
Extension of the wrist and digits along with abduction of the thumb
When targeting the ulnar nerve, what is the correct response to nerve stimulation?
Flexion of the 4th and 5th digits and ADDuction of the thumb
Why is the infraclavicular block considered to be the most painful block?
Because of the multiple muscle layers that must be traversed for a successful block. These muscles include the pectoralis major and minor. Injecting additional subcutaneous local can help improve patient experience
Why is bleeding from the subclavian arter/vein during an infraclavicular block so detrimental?
Because this area can be very difficult to compress and can result in significant bleeding/hematoma.
Why is there an increased risk of LAST during infraclavicular blocks?
Because the needle has to be directed in such a steep angle and it can become difficult to identify the needle tip. Inadvertent injection into vasculature may occur leading to LAST. Frequent aspiration is necessary to decrease risk
Of these three blocks (supraclavicular, infraclavicular and interscalene), which block is considered to pose the least risk of pneumothorax?
Infraclavicular block. Although the risk is less, it can still happen. Inserting the needle in a slight lateral direction decreases the risk of pneumothorax
What part of the brachial plexus does the axillary block target? List all components
The terminal branches. It targets 4 of the 5 terminal branches - all except the axillary nerve. This block does not cover skin on the medial upper arm (intercostobrachial n.) or the skin over the deltoid (axillary n.)
List the borders of the femoral triangle
Sartorius muscle
Adductor longus muscle
Inguinal ligament
“SAIL”
The femoral n. arises from the posterior divisions of L2-4. The roots merge in the psoas major and form the nerve. It then courses between the psoas and iliacus muscles and passes under the inguinal ligament
Once under the inguinal ligament, the femoral n. divides into anterior and posterior divisions. What does the anterior branch supply?
The ventral surface of the thigh and sartorius muscle
Once under the inguinal ligament, the femoral n. divides into anterior and posterior divisions. What does the posterior branch supply?
The quadriceps muscle, the knee join and the medial ligament. The saphenous n. arises from the posterior branch
When combined with what block, the femoral nerve block provides almost complete coverage of the lower extremity?
The sciatic nerve block. The femoral nerve block alone however does provide anesthesia/analgesia for hip, femur, quad and knee procedures.
What two structures must be penetrated to ensure an effective femoral nerve block?
The fascia lata and fascia iliaca. This is regardless of technique (landmark or ultrasound)
If you are performing a femoral nerve block using landmark technique and the inner thigh starts to twitch, what has happened?
The needle is too superficial and medial. This causes stimulation of the sartorius muscle rather than the “patellar snap” that should occur with a proper block.
What are the boundaries of the adductor canal?
Roof: sartorius
Lateral wall: vastus medialis
Remainder: adductor longus or magnus depending on level scanned
The adductor canal starts at the base of the femoral triangle and ends at the adductor hiatus
List some indications for an adductor canal block:
ACL
MCL
patella fracture
vein stripping and harvesting
Supplementation to a sciatic block for foot/ankle surgery
What increases the likelihood of quadriceps weakness when performing an adductor canal block?
More likely with proximal injections and injections with volumes greater than 20ml
When combined with what block, the popliteal sciatic block provides complete coverage of the lower extremity below the knee?
The saphenous nerve block
When performing a popliteal sciatic block, where is the ideal location for local anesthetic placement?
Where the sciatic nerve divides into the tibial nerve and common peroneal nerve.
What motor response will you obtain when blocking the common peroneal and tibial nerve?
Tibial: inversion, & plantar flexion
Common peroneal: eversion & dorsiflexion
“TIPPED”
