Unit 8 - Upper Extremity Blocks Pt 2 Flashcards
A = musculocutaneous n.
B = median n.
C = ulnar n.
D = radial n.
E = axillary a.
axillary block
what nerve must be blocked separately from 3 terminal branches inside neurovascular bundle (axillary block)
musculocutaneous
US transducer orientation for axillary block
Short-axis of the arm distal to the insertion of the pectoralis major muscle
which nerve should be blocked 1st in axillary block (US-guided)
radial n. first due to deeper location
blocking more superficial nerves first can displace & distort anatomic structures, obscuring radial n. view)
what nerve should be blocked first in axillary block (nerve stim technique)
block the nerves that innervate the area of surgery 1st
order of nerve blockade may be different vs. with US-guided
risks of other brachial plexus blocks that are not present with axillary block
- PTX - due to distance from thorax to injection site
- diaphragmatic hemiparalysis
- Horner’s syndrome
vascular structures in close proximity when performing axillary block
axillary artery
axillary veins
basilic vein
3 terminal nerves of the hand that can be blocked at the level of forearm or wrist for FA/hand surgery
radial n
ulnar n
median n
where is LA injected for a radial nerve block
3-5 mL between biceps tendon & brachioradialis
where is LA injected for an ulnar nerve block
Elbow is flexed 90 degrees and LA injected between olecranon & medial epicondyle of humerus
3-5 mL LA
where is LA injected for an ulnar nerve block
Elbow is flexed 90 degrees and LA injected between olecranon & medial epicondyle of humerus
3-5 mL LA
where is LA injected for median nerve block
In antecubital fossa, LA injected medially to brachial artery
forearm block that should be avoided in pt with carpal tunnel
median n block
risk of high volume LA for ulnar n block
Using too high a volume can compress ulnar n. and cause ischemic injury
3 targets of wrist block
radial, ulnar, median nerves
Which nerve is anesthetized by injecting local anesthetic in the antecubital fossa medial to the brachial artery?
median nerve
anatomic landmark for radial n. block at wrist
radial styloid
LA volume for radial n block at wrist
10 mL SQ proximal to radial styloid
field block
landmarks to block ulnar nerve at wrist
- ulnar styloid
- ulnar pulse
- flexor carpi ulnaris tendon (FCU)
landmarks to block median n at wrist
- flexor carpi radialis (FCR)
- flexor palmaris longus (FPL)
LA used to block median n at wrist
Inject 5 mL between FCR and FPL
Do NOT use epi-containing solution (risk ischemic injury)
is a median n block at wrist sufficient for wrist tourniquet?
yes - no additional nerve block required
how is digital nerve block performed
Inject 2-3 mL of LA at the base of both sides of the finger to provide anesthesia to finger
avoid epi
best uses for a bier block
procedures that produce minimal postoperative pain (ex. carpal tunnel release, Dupuytren’s contracture surgery)
relative tourniquet contraindications
- crush injury of extremities
- inability to identify peripheral veins
- cellulitis
- compound fractures
- severe PVD
- sickle cell disease
Only absolute contraindication: patient refusal
prepping for bier block tourniquet
- Place a double cuff tourniquet to patient but don’t inflate it
- Place 22g PIV in a distal peripheral vein of operative extremity (placement in the hand is best for hand and wrist procedures)
- Elevate extremity for 1-2 minutes to allow for passive exsanguination
steps to apply esmarch and inflate tourniquet for bier block
- Wrap Esmarch around extremity to further exsanguinate it. Begin at distal limb, move proximally until you reach the distal tourniquet cuff
- Inflate DISTAL cuff - helps further exsanguinate arm, tests distal cuff on patient)
- Inflate PROXIMAL cuff
- Deflate DISTAL cuff
- Remove Esmarch bandage
LA used for bier block
large volume of dilute anesthetic (50 mL of 0.5% lidocaine)
do NOT use bupivacaine or epi
bier block tourniquet inflation pressure
~250 mmHg (or at least 100 mmHg over SBP)
additive that can be used in bier block that helps with postop pain but does not increase bleeding risk
ketorolac
when should bier block be redosed
after 90 min
how early can tourniquet pain begin
as early as 25 min
most common reason a pt can’t tolerate a procedure with a bier block for over an hour
tourniquet pain
max bier block tourniquet inflation time
2 hours
what should you do if the procedure with bier block lasts > 2 hrs or pt cant tolerate pain
switch to the distal cuff without letting the confined LA wash out into systemic circulation
- Proximal tourniquet inflated
- Inflate distal cuff (tissue under this cuff already anesthetized)
- Deflate proximal cuff
most significant risk with bier block
LAST
minimum time tourniquet must be inflated for bier block
20 min
when can you deflate tourniquet for bier block if time since last injection is 20-40 min ago
Deflate, immediately reinflate, deflate again at 1 min
> 40 min - deflate
considerations for lower extremity bier block
- larger LA volume (inc risk LAST)
- tourniquet 350-400 mmHg
tourniquet on calf - same LA volume and inflation pressure as upper extremity
considerations for lower extremity bier block
- larger LA volume (inc risk LAST)
- tourniquet 350-400 mmHg
tourniquet on calf - same LA volume and inflation pressure as upper extremity
considerations for lower extremity bier block
- larger LA volume (inc risk LAST)
- tourniquet 350-400 mmHg
tourniquet on calf - same LA volume and inflation pressure as upper extremity
Which nerve is anesthetized by injecting local anesthetic between the biceps tendon and brachioradialis?
radial
When performing an infraclavicular block with nerve stimulation, what response suggests posterior cord stimulation?
finger extension
(Radial n)
When performing an infraclavicular block with nerve stimulation, what response suggests lateral cord stimulation?
elbow flexion + forearm supination
(musculocutaneous)
When performing an infraclavicular block with nerve stimulation, what response suggests medial cord stimulation?
ulnar deviation
(ulnar n)
medial cord
A = ulnar n
B = median n
C = radial n
D = musculocutaneous n
supplies sensation to anterolateral aspect of forearm
musculocutaneous n
may be missed in axillary block
where do the cords of the brachial plexus transition to terminal branches
axilla
beyond lateral border of pec minor
where do the cords of the brachial plexus transition to terminal branches
axilla
beyond lateral border of pec minor
most common causes of median n injury
AC IV insertion
axillary approach to brachial plexus
which PNB has the highest incidence of chylothorax
infraclavicular
