Upper Extremity Nerve Blocks Flashcards
indications for regional anesthesia
- primary anesthetic
- post-op pain management
- history of severe PONV or risk of MH
- patient too ill for general
- physician/surgeon preference
absolute contraindications
- patient refusal
- active bleeding in anticoagulated patient
- proven allergy to LA
- local infection at the site of proposed block
relative contraindications
- respiratory compromise
- inability to cooperate/understand the procedure
- an anesthetized patient
- bleeding diathesis secondary to an anticoagulant or genetic disorder
- bloodstream infection
- preexisting peripheral neuropathy
3 benefits of ultrasound over traditional landmark technique in peripheral nerve blocks.
- visualize anatomic structures
- visualize real time needle movements
- see spread of local anesthetic
how much LA is enough for a block?
- most references say 20-40 mL
- some new research have demonstrated successful blocks with 5 mL
amount and type of LA depends on what?
- patient factors
- timing of procedure
- procedure
- purpose of block
what determines spread of LA
volume
what determines density of block
concentration
procaine
ester
slow onset
DOA 60-90 min
chloroprocaine
ester
fast onset
DOA 30-60 min
tetracaine
ester
slow onset
DOA 180-600 min
lidocaine
amide
fast onset
DOA 90-120 min
mepivacaine
amide
fast onset
DOA 120-240 min
ropivacaine
amide
slow onset
DOA 180-600 min
bupivacaine
amide
slow onset
DOA 180-600 min
prior to block procedure what does the anesthetist need to do?
- verify correct patient
- obtain informed consent
- verify correct procedure
- verify correct extremity
- gather all necessary equipment
- place patient on oxygen (ETCO2)
- obtain baseline VS and monitor during procedure
- administer proper and adequate sedation
cervical plexus block indications
- carotid endarterectomy
- superficial neck surgery
- clavicle fractures
what nerve roots give rise to the cervical plexus?
C2-C4
major nerves of the cervical plexus (4)
- transverse cervical
- great auricular
- lesser occipital
- supraclavicular
where does the cervical plexus block provide anesthesia?
- anterolateral neck
- anterior and retro-auricular areas
- anterior chest just inferior to clavicle
cervical plexus block transducer placement
- transverse orientation right over SCM muscle
- facial plane between SCM and ASM is where the plexus is located on US
cervical plexus block technique
- patient position = turned with head toward non-operative side
- transducer placed at midpoint of SCM and moved laterally until posterior edge identified
- identify brachial plexus between ASM and MSM
- cervical plexus located in plane above prevertebral fascia
- needle passed lateral to medial, in plane to area between SCM and prevertebral fascia
- following negative aspiration inject 5-10 mL LA (NEVER more than 5 mL at a time)
cervical plexus block pearls
- visualization of nerves in plexus is NOT necessary
- since plexus nerves are purely sensory, low concentration of LA used
cervical plexus block side effects/complications
- intrathecal injection due to close proximity of vertebral nerve roots
- potential intravascular injection in vertebral artery
brachial plexus
- ventral rami of C5-T1 nerve roots
- contributions from C4 and T2 are often minor or absent
- roots exiting the vertebral foramen converge and diverge into trunks, divisions, cords, branches, and finally terminal nerve branches
- suppplies sensory and motor innervation to upper extremity
Brachial plexus pnemonics
- Robert Taylor Drinks Cold Beer = Roots, Trunks, Divisions, Cords, Branches (terminal)
- Most Alcoholics Really Must Urinate = Musculocutaneous, Axillary, Radial, Median, Ulnar
number of roots, trunks, divisions, cords, and branches
- five roots
- three trunks
- six divisions
- three cords
- five branches
five roots of brachial plexus
C5, C6, C7, C8, T1
three trunks of brachial plexus
- superior (C5 and C6)
- middle (C7)
- inferior (C8 and T1)
six divisions of brachial plexus
-three anterior and three posterior divisions
three cords of brachial plexus
- lateral cord (anterior divisions of upper and middle trunk; so has contributions from C5, C6, C7)
- posterior cord (all three posterior divisions (contributions from ALL five roots)
- medial cord (anterior division of lower trunk; contributions from C8 and T1)
five branches of brachial plexus
- musculocutaneous (division of lateral cord)
- axillary (comes off posterior cord)
- median (formed by lateral and medial cord)
- radial (from posterior cord)
- ulnar (from medial cord)
proximal branches of brachial plexus
- dorsal scapular
- phrenic
- long thoracic
lateral branches of brachial plexus
- suprascapular
- subclavius
- lateral pectoral
medial branches of brachial plexus
- medial pectoral
- medial cutaneous to arm and forearm
posterior branches of brachial plexus
- upper and lower subscapular
- thoracodorsal
C5 motor innervation
shoulder abduction
C6 motor innervation
elbow flexion
C7 motor innervation
elbow extension
C8 motor innervation
finger flexion
T1 motor innervation
finger abduction/adduction
block evaluation
baseline push, pull, pinch, pinch
- extension (push) - radial nerve
- flexion (pull) - musculocutaneous (biceps), ulnar (hand)
- pinch - thumb side radial
- pinch - middle finger median
- pinch - pinky side ulnar
supraclavicular block
- relaible upper extremity block for procedures involving the upper arm and hand
- trunk and division level block
- brachial plexus is MOST compact at this level
SCB technique
- transverse image using in-plane needle insertion
- trunks and divisions are found lateral to pulsating subclavian artery and superior to first rib
- needle inserted lateral to medial toward the inferior aspect of the plexus where the rib and artery meet (AKA Corner pocket)
- following negative aspiration, incremental injections of 5 mL are done
SCB side effects + complications
- increased risk of phrenic nerve paralysis and stellate ganglion block (ptosis, anhidrosis, miosis)
- pneumothorax
- inadvertent arterial puncture due to close proximity to subclavian
interscalene block (ISB)
- root level block
- primary brachial plexus block for procedures involving shoulder and proximal upper arm (suprascapular nerve)
- nerve roots C5-C7 are found in the interscalene groove between ASM and MSM
ISB technique
- patient in supine position with head turned to non-operative side
- high frequency linear array transducer place in mid-clavicular fossa and moved cephalad
- hypoechoice roots located between ASM and MSM
- 5 cm B bevel needle
- incremental injection of 5 mL up to 20-30 mL
ISB pearls
- nerve stimulation not required, however if used when it occurs at 0.5 mA, the needle should be withdrawn slightly
- pre-procedure scan with color doppler to limit potential IV injections into veretebral artery/vein
- stoplight or snowman may be result of branching of either C5 or C6 (so may not be getting as much coverage as you think)
ISB side effects + complications
- phrenic blockade nearly 100% of the time
- stellate ganglion block (horners syndrome –> ptosis, miosis, anhidrosis)
- LAST
- high spinal if the dural sheath is punctured
- injury to dorsal scapular and long thoracic nerves (course through the MSM)
infraclavicular block
- cord level block
- good alternative to supraclavicular block, especially in those with severe COPD or respiratory insufficiency
- cords (lateral, posterior, medial) are labeled by their relation to the axiallary artery
- for procedures of lower upper arm and forearm
IFCB technique
- patient in supine position with head turned to non-operative side
- transducer placed perpendicular to clavicle just medial to coracoid plexus
- short axis image
- cords arranged around axillary artery
- 22G 8 cm needle inserted in-plane, cephalad to caudal
- incremental injection of 20-30 mL of LA around axillary artery
IFCB pearls
- depending on body habitus, low-frequency transducer may be needed
- additional subQ injection of LA may be warranted (BC a lot deeper)
- sliding needle medially increases potential for pneumo or hemothorax
- thoraco-acromial artery and pectoral veins pass between the pectoral muscles; doppler can be used to identify to prevent inadvertent puncture
IFCB complications
- pneumo/hemothorax
- vascular puncture
- LAST
axillary block
- terminal branches of brachial plexus (4 not all 5)
- musculocutaneous, radial, ulnar, median
- good for procedures below the elbow
- US made it less attractive because other blocks can be done easier with fewer complications
axillary technique
- patient in supine position with head turned to non-operative side and arm abducted and rotated externally
- high-frequency linear array transducer placed in the crease formed by the biceps muscle and pec major
- 22G 5cm B bevel needle inserted in plane
- incremental injection of 20-40 mL
axillary pearls
- compressing the veins may decrease risk of vascular puncture
- block radial first due to deep location
- pre-procedure scan = slide transducer distally to appreciate each of the nerves then follow then proximally to the origin
axillary complications
- complications not common, but increased risk of vascular puncture due to frequent redirection of needle to get adequate spread
- paresthesia from multiple punctures may result in neuropathy
- multiple veins located around artery too so BE CAREFUL
nerve blocks at the elbow
- rescue for incomplete block
- localized procedure of radial, ulnar, or median (median and ulnar blocked with the arm abducted)
- find the contrast!!! all three nerves are located near vascular structures or bone
median nerve
- courses along brachial artery in upper arm to elbow (brachial verified with color doppler)
- needle inserted in plane lateral to medial
- 4-5 mL LA
- additional 2-3 mL if circumferential spread not noted
radial nerve
- scan distally along the lateral humerus
- ID nerve as it takes a more anterior course along the humerus
- needle inserted in plane, lateral to medial
- 4-5 mL LA
- additional 2-3 mL if circumferential spread not noted
ulnar nerve
- scan medially to ID the medial epicondyle
- scan proximal to distal along the arm to ID where the nerve enters
- needle inserted in plane, medial to lateral
- 4-5 mL LA
- additional 2-3 mL if circumferential spread not noted
IV regional anesthesia (IVRA) or Bier block
- described by Dr. Bier over 100 years ago
- LA injected into venous system of an extremity that has been exsanguinated by compression and isolated by tourniquet
IVRA direct MOA
local bathing nerve endings in tissue
IVRA indirect MOA
LA transported to substance of the nerves via vasa nervorum
IVRA indications
- brief surgical procedures - ganglion cyst, carpal tunnel, Dupuytren’s contractures, fracture reduction
- treatment for regional pain syndromes - analgesia, reduce neurogenic inflammation
IVRA absolute contraindications
patient refusal
IVRA relative contraindications
- injury to extremity (crush or open fracture)
- inability to cannulate peripheral vein
- local skin infection or cellulitis
- true allergy to LA
- preexisting AV fistula
- sickle cell disease
- surgery greater than 1 hour
IVRA procedure
- place IV cath as distal as possible in extremity
- apply double-pneumatic tourniquet on proximal arm
- elevate extremity and apply esmarch bandage
- occlude artery
- inflate proximal cuff 50-100 mmHg over patient’s SBP -remove esmarch bandage
- inject 30-50 mL 0.5-1.0% lidocaine
- if patient complains of tourniquet pain, inflate distal cuff first, then deflate proximal cuff
IVRA pearls
- tourniquet MUST remain inflated for at least 30 min following injection of LA, regardless of surgery length
- after 30 min the cuff tourniquet deflation occurs in a cyclical fashion
- cuff deflated then instantly reinflated
- patient evaluated for signs of LAST or other complications
- wait 1-2 min
- repeat (do this for 5-10 min)
IVRA side effects + complications
- if lower extremity IVRA is performed, there will be 100% incidence of LA leakage under tourniquet (observe S/S LAST)
- damage to radial, median and ulnar nerves
- compartment syndrome
- arterial thrombosis
- death or permanent brain damage
complications of regional (4)
- LAST
- nerve injury
- intravascular puncture/injecttion
- death
LAST
- local anesthetic systemic toxicity
- serious but rare event during regional
- most commonly occurs from inadvertent IV injection
- seizures (blocking of inhibitory neurons), bradycardia (blocking of cardiac ion channels)
- V fib is most serious complication
main offender of LAST
bupivacaine
LAST clinical presentation
- classic presentation, rapid onset usually within 1 min
- progression of subjective symptoms - agitation, tinnitus, circumoral numbness, blurred vision, metallic taste
- followed by - muscle twitching, unconsciousness, seizures
- very HIGH levels - cardiac + respiratory arrest
incidence of LAST
0.4 per 10,000
most common blocks with LAST occurrence
- epidural
- axillary
- ISB
prevention strategies for LAST
- test dose (45 mg lido, 15 mcg epi)
- incremental injection with aspiration
- use of pharmacologic markers
- ultrasound
LAST treatment
- prompt recognition and diagnosis
- airway management
- seizure suppression - benzos, succ
- prevent hypoxia and acidosis
- lipid emulsion therapy
- vasopressors - epi < 1 mg/kg
- supportive care (some even ECMO)
lipid therapy MOA
- capture LA in blood (lipid sink)
- increase fatty acid uptake by mitochondria
- intereference of Na+ channel binding
- promotion of calcium entry
- accelerated shunting
lidocaine max doses
- 4 mg/kg
- 7 mg/kg with epi
mepivacaine max doses
- 4 mg/kg
- 7 mg/kg with epi
bupivacaine max dose
3 mg/kg
ropivacaine max dose
3 mg/kg
procaine max dose
12 mg/kg
chloroprocaine max doses
- 11 mg/kg
- 14 mg/kg with epi
prilocaine max doses
- 7 mg/kg
- 8.5 mg/kg with epi
tetracaine max dose
3 mg/kg
preexisting risk factors for nerve injury with regional
- DM
- pre-existing neurologic disease
- smoking
- increased BMI
- male
