Week 5 Upper Peripheral Nerve Blocks Flashcards
What are the five indications for regional anesthesia?
Primary anesthetic post-operative pain management history of severe PONV or risk of MH Patient is too ill for general anesthesia physician (surgeon) preference
Benefits of Regional Anesthesia (6)
decreased risk of PONV decreased postop pain decreased LOS increased patient satisfaction maintained upper airway adn pharyngeal reflexes increased gastric mobility
Absolute contraindications for regional anesthesia (4)
patient refusal
active bleeding in anticoagulated patient
proven allergy to a local anesthetic
local infection at the site of the proposed block
Relative contraindications for regional anesthesia
respiratory compromise
uncooperative patient/ neurological disease/psychiatric disease
an anesthetized patient
bleeding diathesis secondary to an anticoagulant or genetic disorder
blood stream infection
pre-existing peripheral neuropathy
Complications of Regional Anesthesia (4)
intravascular injection/LAST
direct nerve injury/intraneural injections
vascular injury/hematoma
infection
What region has the highest incidence of LAST?
epidural> axillary > interscalene
What is LAST?
local anesthetic systemic toxicity
systemic delivery of large quantities of LA via inadvertent intravascular injection
What channels are depressed with LAST?
Sodium, potassium and calcium
Neuro and cardiac symptoms of LAST
lack of inhibition of excitatory neurons-> seizure
cardiac: decreased contractility, arrhythmias (brady first), vfib most serious
What LA carries the most reported deaths?
Bupivacaine
What drugs are less cardiotoxic for LAST?
shorter acting drugs
What are clinical signs of LAST?
progressive CNS excitation agitation tinnitus circumoral numbness blurred vision metallic taste muscle twitching unconsicousness seizure cardiac and respiratory arrest
What are safety precautions for LAST?
ultrasound guided regional anesthesia aspiration before injection incremental injection lower doses test dose awake/sedated patients midazolam
Treatment of LAST
prompt recognition and diagnosis
airway management priority (seizure suppression, benzo) prevent hypoxia and acidosis
Lipid emulsion therapy
Vasopressors Epi< 1mcg/kg, no vasopressin
What is the dose for lipid emulsion therapy?
1.5ml/kg 20% rapidly Q2-3minutes
infusion 0.25ml/kg/min (IDW)
What are the benefits of UGRA vs. traditional landmark technique?
Visualization improvement of block quality use of lower doses of local anesthetic less painful administration improved patient satisfaction safer
What can you visualize with the US?
anatomic structures
real time needle movements
spread of LA
Define UGRA
in-plane/longitudinal preferred allows visualization of entire needle
What is an ART manuever?
alignment- sliding
rotation
tilting- maximizing angle of incidence of beam to target structure
Where are the peripheral nerve stimulators placed?
negative lead attaches to skin
positive lead attaches to needle
Define peripheral nerve stimulator for regional anesthesia?
controlled stimulating pulse of variable amplitude
What is the goal of peripheral nerve stimulator?
maintenance of motor stimulation with minimal amplitude
When using the PNS, when do you stop?
if motor response seen with <0.2mA
chance of intraneural injection
When do you turn on the stimulator?
when the needle has entered the skin
How much LA is enough?
most references recommend 20-40mL per block
some authors have demonstrated successful, complete interscalene blocks with as little as 5ml
What does the amount and type of LA depend on?
patient factors
procedure
purpose of the block
timing of the procedure
Pre-procedure Checks
verify the correct patient obtain informed consent verify the correct procedure verify the correct extremity gather all necessary equipment Place patient on O2/ etCo2 during monitoring (sedation_ obtain baseline VS and monitor during the procedure administer proper/adequate sedation
Indications of a cervical plexus block
carotid endarterectomy
superficial neck surgery
clavicle fractures
lateral surface of ear
Contraindications of cervical plexus block
SOB
COPD
HEmi-diaphragm
Describe a cervical plexus block
branches of cervical nerve roots C2-C4
provides anesthesia to the anterolateral neck, anterior and retro auricular areas and the anterior chest just inferior to the clavicle
What are the major nerves in the cervical plexus?
transverse cervical nerve great auricular nerve lessor occipital nerve supraclavicular nerve phrenic nerve?
PEARLS of Cervical plexus
visualization of nerves in plexus is not neccessary
since plexus nerves are purely sensory, lower concentration of LA used
Technique of Cervical Plexus
patietn position with head turned to non-operative side
transducer placed at midpoint of SCM moved laterally until posterior edge is identified
identify brachial plexus between anterior and middle scalene muscle
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, PF NS for hydro dissection then inject 5-10ml of LA
What needle is used for cervical plexus?
20 g 2” needle
Side effects/Complications of cervical plexus?
poor needle visualization can result in intrathecal injection due to close proximity of vertebral nerve roots
and potential intravascular injection in vertebral artery
What is the brachial plexus?
large network of nerves- neck and axilla and innervate upper extremity
consist of ventral rami of the C5-T1 nerve roots
What innervation runs through the brachial plexus?
brachial plexus supplies sensory and motor innervation to the upper extremity
How many roots are in the brachial plexus?
five
How many trunks are in the brachial plexus?
three
How many divisions are in the brachial plexus
six
How many cords are in the brachial plexus?
three
How many branches are in the brachial plexus?
five
What do the proximal branches innervate?
dorsal scapular, phrenic and long thoracic
What do the lateral branches innervate?
suprascapular, subclavian, lateral pectoral
What do the medial branches innervate?
medial pectoral, medial cutaneous to arm and forearm
What is posterior?
upper and lower subscapular, thoracodorsal
C5 brachial plexus dermatomes innervate
shoulder abduction
C6 brachial plexus dermatomes innervate
elbow flexion
C7 brachial plexus dermatomes innervate
elbow extension
C8 brachial plexus dermatomes innervate
finger flexion
T1 brachial plexus dermatomes innervate
finger abduction/adduction
How do evaluate a brachial plexus block?
Baseline: push, pull, pinch, pinch
post-procedure allows you to differentiate blockade
When you evaluate a brachial plexus block what does push represent?
radial nerve
triceps muscle
When you evaluate a brachial plexus block what does pull represent?
musculocutaneous nerve
biceps muscle
When you evaluate a brachial plexus block what does pinch represent?
ulnar nerve
median nerve
What are the four brachial plexus blocks?
interscalene
supraclavicular
infraclavicular
axillary
Indications for a interscalene block?
procedures of the shoulder and proximal upper arm suprascapular nerve (scapula)
Where does an interscalene block occur?
root level block
WHere are the nerve roots C5-C7 found?
in the interscalene groover between the anterior and middle scalene muscles
Describe the ISB technique
supine position with head turned to non-operative side
high frequency linear array transducer placed in the mid-clavicular fossa and moved cephalad
hypoechoic roots located between the ASM and MSM
what needle is used for an ISB
5cm, B bevel needle
How much LA is injected for ISB
incremental injection of 5ml up to 20-30ml
If using nerve stimulation for ISB, when do you need to withdrawl needle?
nerve stimulation is not required, however is used when it occurs at 0.5mA, the needle should be withdrawn slightly
What should be performed with the US prior to injection in an ISB?
pre-procedure scan with color doppler
limit potential inadvertent injections and identify anatomic variations
Side effects/ complications of ISB
phrenic blockade occurs 100% of time
stellate ganglion blockade (Horner’s) syndrome is common
LAST
high spinal
injury to the dorsal scapular and long thoracic nerves
What are symptoms of horner’s syndrome?
ptosis
miosis
anhidrosis
Indications for ISB continuous catheter
total/hemi shoulder arthroplasty, proximal humerus, distal clavice, rotator cuff
Contraindications to ISB continuous catheter
contralateral diaphragmatic paralysis, significant OSA/respiratory distress
Where is the catheter placed for ISB?
near C5-C7 roots between ASM and MSM
What supplies are needed for ISB with continuous catheter?
1% lidocaine 27g needle
4” echogenic tuoy needle, wire stylet catheter with clamp, PS NS for hydro dissection
What position should the catheter be placed for ISB continuous catheter?
lateral position, allows for posterior placement away from surgical field
When using a nerve stimulator what nerve can be stimulated?
dorsal scapular nerve
Where is the catheter going in ISB CC?
corner pocket between C5 and fascia above
What LA is best for postop pain in ISB CC?
0.25% marcaine and 0.2% ropi at 6 ml/hr (titrate)
What LA is best for surgical pain in ISB CC?
0.375%-0.5% marcaine/Ropi
When do you d/c infusion and assess with ISB CC?
SOB or difficulty swallowing
indications for a supraclavicular block?
reliable upper extremity block for procedures of the upper arm and hand
What levels does a supraclavicular block occur?
trunk and division level
What level is the brachial plexus most compact?
supraclavicular level
Describe the SCB technique
supine head turned away
transverse image using in-plane needle insertion
trunks/ divisions are found lateral to the pulsating subclavian artery and superior to the first rib
needle is inserted lateral to medial toward the inferior aspect of the plexus where the rib and artery meet (corner pocket)
Following negative aspiration, incremental injections of 5ml is accomplished (30 ml max)
What will twitch in a SCB with 0.4-.05mA of stimulation?
hand twitch
SCB side effects and complications
increased risk of phrenic nerve paralysis and stellate ganglion block
pneumothorax is most important complication
because of the proximity of the subclavian artery, there is the possibility for inadvertent arterial puncture (hematoma/LAST)
Infraclavicular block is what level block?
cord level block
Who benefits from a infraclavicular block?
alternative to supraclavicular block
patients with COPD or respiratory insufficiency
How are the cords labeled?
in relation to the axillary artery
Indications for a infraclavicular block?
elbow forearm and hand
Infraclavicular technique
patient placed in supine position with head turned to non-operative side
transducers is placed perpendicular to the clavice just medial to the corarcoid plexus
short axis image
cords are arranged around the axillary artery
What needles are used in the infraclavicular technique?
22gauge 4” stimulating needle inserted in plane, cephalad to caudal
Describe the injection process of infraclavicular technique
20-30ml of LA around axillary artery
5-10ml in area of lateral cord
10-20 ml in area of posterior cord
U shaped spread of LA around the artery (will cover medial cord)
Can you use a low-frequency transducer for infraclavicular block?
yes, depends on patients body habitus
What block may require additional SQ LA?
infraclavicular block
During a infraclavicular block if the needle is slide medially what complications may occur?
pneumothorax and hemothorax
What artery/veins do you need to be aware of with an infraclavicular block?
thoraco-acrominal artery and pectoral vein passes between the pectoral muscles
Where is the first twitch noted when performing a infraclavicular block?
elbow flexion from musculocutaneous nerve
need response in hand (flexion and extension) for anesthesia of hand
Complications of an infraclavicular block?
poor needle visualization may result in advertent:
pneumothorax/hemothorax
vascular puncture
LAST Event
Where does an axillary block occur?
directed at the terminal branches of the brachial plexus
radial nerve
ulnar nerve
median nerve
Indications of axillary block?
procedures below the elbow
The axillary technique
patient supine with head turned to the non-operative side, arm abducted and rotated externally
high frequency linear array transducer is placed in teh crease formed by the biceps msucle and pectoris major
What needle is used for axillary blocks?
22g 5cm B bevel needle inserted in-plane cephalad to caudal direction
incremental injection of 20-40ml
How can you improve the axillary block?
compress veins to decrease the rise of puncture
block the radial nerve first because its deep location
Describe the pre-procedural scan for axillary block?
slide the transducer distally to appreciate each of the nerves, then follow them proximally to their origin
trace axillary artery towards elbow, the nerve stays adjacent is the median nerve
the nerve that breaks away from artery in axilla is ulnar nerve
radial nerve emerges from behind humerus tangential to it
Complications of axillary block
not common
increased risk of vascular puncture because needle must be re-directed several times to achieve adequate local anesthetic distribution
paresthesia from multiple needle punctures may result in in neuropathy
multiple veins located around artery- risk of LAST
if tourniquet required, intercostobrachial block must be performed
Transarterial technique
intentional penetration of axillary artery
aspiration of blood as end point for determining needle in sheath
LA skin wheal raised about the artery, insert needle with aspiration, when no longer able to aspirate blood LA is injected
test dose 3-5ml
observe for 1 minute
What is the purpose of nerve blocks at the elbow?
rescue for incomplete block or selective to minimize amount fo anesthesia
Nerve blocks at the elbow and wrist are
sensory blocks, primarily
Where are nerve blocks at the wrist and elbow localized to?
radial nerve
ulnar nerve
median nerve
What are all three nerves of a elbow or wrist block close too?
vascular structures or bone
find the contrast
Median nerve block at the elbow US technique
courses alongside the brachial artery in the upper arm to the elbow
needle inserted in-plane lateral to medial
following negative aspiration inject 4-5ml of LA
additional 2-3 ml can be inejected if circumferential spread is not noted
Radial nerve US Technique
scan distally along the lateral humerus
identify the nerve as it takes a more anterior course along the humerus
needle inserted in-plane, lateral to medial
following negative aspiration, inject 4-5mL of LA
an additional 2-3 ml may be injected if circumferential spread is not obtained
Ulnar nerve block at the elbow US technique
scan medially to identify the medial epicondyle
insert between medial condyle of humerus and olecranon process of ulna
scan proximal and distal along the arm to identify where the nerve enters
needle inserted inplane, medial to lateral
following negative aspiration, inject 4-5ml of LA
an additional 2-3ml may be injected if circumferential spread not obtained
risk of nerve entrapment
Define Intravenous regional anesthesia
block in which local anesthetic is injected into the venous system of an extremity that has been exsanguinated by compression and isolated by a tourniquet
technically safe, simple and rapid means producing surgical anesthesia of the extremity
When is IVRA best?
procedures <1hour
Risk of IVRA
LA entering central circulation- emergency equipment needed
what are the two mechanisms of IVRA
direct- local bathing nerve endings in the tissue
indirect- LA transported to the substance of the nerves via the vasa nervorum
Indications of IVRA
brief surgical procedures and manipulations ganglion cyst excision carpal tunnel release dupuytren's contractures fracture reduction (mostly in peds) treatment for regional pain syndromes analgesia reduce neurogenic inflammation
Absolute contraindications for IVRA
patient refusal
Relative contraindications of IVRA
injuries to the extremity (crush or open) inability to cannulate peripheral vein local skin infection or cellulitis true allergy to LA pre-existing arteriovenous fistula sickle cell disease surgery greater then one hour
IVRA procedure
- place IV in distal vein
- apply a double-pneumatic tourniquet on the proximal arm
- Elevate the extremity and apply an esmarch bandage
- occlude the axillary
- inflate the proximal cuff to 250mmHg or 100mmHg above patient’s systolic BP for upper extremity
- remove esmarch bandage
- inject 30-50ml of 0.5-1% lidocaine
- if patient complains of tourniquet pain, inflate distal cuff first then deflate proximal cuff
How long does the tourniquet have to be inflated after the injection of LA regardless of surgical procedure?
30 minutes
After 30 minutes, how does the cuff tourniquet deflate?
cyclical fashion cuff deflated, then instantly reinflated watch for complications wait 1-2 minutes repeat
What complications do you assess for while tourniquet as it cycles?
signs of LAST or others
Side effects and complications of IVRA
if lower extremity, 100% incidence of LA leakage under the tourniquet (observe for symptoms of last) damage to radial, median and ulnar nerve compartment syndrome arterial thrombosis death or permanent brain damage
Complications of regional
LAST
nerve injury
intravascular puncture/injection
death
Nerve injury occurs by
direct needle trauma
local anesthetic neurotoxicity
pre-existing patient factors
patient’s perception of postop course
What are patient factors that lead to nerve injury?
diabetes pre-existing neurologic disease smoking increased BMI male
