Ultrasound-guided upper extremity blocks Flashcards
The implications for regional anesthesia include
primary anesthetic post-operative pain management history of severe PONV or risk of MH patient is too ill for general anesthesia physician (surgeon) preference
Absolute contraindications include
patient refusal (make sure they’re saying no for the right reasons)
active bleeding in an anticoagulated patient
proven allergy to a local anesthetic
local infection at the site of proposed block
Relative contraindications include
respiratory compromise
inability to cooperate/understand the procedure
an anesthetized patient?–> more pediatric blocks are done under general anesthesia
bloodstream infection
bleeding diathesis secondary to an anticoagulant or genetic disorder
preexisting peripheral neuropathy
Describe the benefits that ultrasound offers over traditional landmark technique.
Visualization- anatomic structure, real-time needle movements, & spread of local anesthetic
safer-> yes but there is a learning curve
How much local anesthetic should be infused?
20-40 mLs/blocker
some authors have demonstrated successful, complete interscalene blocks with as little as 5 mL
Amount & type of local anesthetic depends on:
patient factors
timing of the procedure
procedure
purpose of block
Describe which esters have a fast onset and slow onset
procaine- slow
tetracaine-slow
chloroprocaine- fast
Describe which amides have a fast onset and slow onset
lidocaine- fast
mepivacaine- fast
ropivicaine- slow
bupivicaine- slow
Prior to beginning any procedure
verify the correct patient obtain informed consent verify the correct procedure verify the correct extremity gather all necessary equipment place the patient on oxygen obtain baseline VS and monitor during the procedure administer proper/adequate sedation
Indications for a cervical plexus block include
carotid endarterectomy
superficial neck surgery
clavicle fractures
Cervical plexus block is performed at
branches of cervical nerve roots C2-C4
Major nerves of the cervical plexus include **
transverse cervical nerve greater auricular nerve lessor occipital nerve supraclavicular nerve -phrenic nerve- maybe not full block but will get some sort of phrenic nerve involvement
Cervical plexus block provides anesthesia to
the anterolateral neck, the anterior and retro-auricular areas and the anterior chest just inferior to the clavicle
Describe the cervical plexus technique.
patient positioned with head turned to non-operative side
transducer placed at midpoint of SCM m. moved laterally until posterior edge is identified
identify brachial plexus between anterior and middle scalene m.
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 of LA
Cervical plexus pearls include
visualization of nerves in plexus is not necessary
since plexus nerves are purely sensory, low concentration LA used (0.25% is typically max)
Poor needle visualization when performing a cervical plexus block can result in
intrathecal injection due to close proximity of vertebral nerve roots
potential intravascular injection in vertebral artery
The brachial plexus consists of
ventral rami of the C5-T1 nerve roots
contribution from C4 & T2 are often minor or absent
Describe the path of the brachial plexus
roots–> trunks–> divisions–> cords–> branches–> nerve terminals
With a few exceptions, the brachial plexus supplies
sensory & motor innervation to the upper extremity
Describe the amount of roots, trunks, divisions, cords, & branches of the brachial plexus
Five roots three trunks six divisions three cords five branches
The proximal branches of the brachial plexus include
dorsal scapular, phrenic, long thoracic
The lateral branches of the brachial plexus include
suprascapular, subclavius, lateral pectoral
The medial branches of the brachial plexus include
medial pectoral, medial cutaneous to arm and forearm
The posterior branches of the brachial plexus include
thoracondorsal
upper & lower subscapular
The posterior cord is responsible for
extensions
Describe the motor innervation that C5 provides
shoulder abduction
Describe the motor innervation that C6 provides
elbow flexion
Describe the motor innervation that C7 provides
elbow extension
Describe the motor innervation that C8 provides
finger flexion
Describe the motor innervation that T1 provides
finger abduction/adduction
The baseline block evaluation includes
have the patient “push, pull, pinch, pinch”
The post-procedure block evaluation includes
differential blockade
mantel effect
Describe the order in which nerves are blocked.
Sympathetic, sharp pain, proprioception, motor
Type B, Type C, Type A beta, gamma, & delta, & then Type A alpha
Describe the different types of brachial plexus blocks
supraclavicular
interscalene
infraclavicular
axillary
The supraclavicular block is a reliable upper extremity block for procedures involving the
upper arm & hand
The supraclavicular block is performed at the
trunk & division level
At this level, the brachial plexus is most compact
supraclavicular
Describe the SCB technique
transverse image using in-plane needle insertion
the trunks/divisions are found lateral to the pulsating subclavian artery & superior to the first rib
needle is inserted lateral to medial toward the inferior aspect of the plexus where the rib & artery meet (aka “the corner pocket”)
following negative aspiration, incremental injections of 5 mL is accomplished
Side effects and complications of the supraclavicular block include
increased risk of phrenic nerve paralysis & stellate ganglion block
pneumothorax is the most important complication
b/c of the proximity of the subclavian artery, there is the possibility for inadvertent arterial puncture
The interscalene block is a
root level block
The interscalene block is the primary brachial plexus block for procedures involving the
shoulder & proximal upper arm
-suprascapular nerve
Nerve roots C5-C7 are found in the interscalene groove between
the anterior & middle scalene muscles
Describe the interscalene block 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 & MSM
6 cm, B bevel needle
incremental injection of 5 mL up to 20-30 mL
If damaged, this nerve can cause winged scapula
long thoracic nerve
Recent studies for the interscalene block demonstrate that the “stoplight” or “snowman” sign may result from
the branching of either C5 or C6
For the interscalene block, a pre-procedure scan with
color Doppler should be performed prior to injection to limit potential inadvertent injections and identify anatomic variations
Side-effects/complications of interscalene blocks include
Phrenic blockade occurs nearly 100% of the time
local anesthetic system toxicity (LAST)
high spinal
injury to the dorsal scapular and long thoracic nerves
Stellate ganglion block (aka Horner’s syndrome) is common- Ptosis, miosis, anhidrosis
The infraclavicular block is a
cord level block
The infraclavicular block is a good alternative to the
supraclavicular block, especially in patients with severe COPD or respiratory insufficiency
The infraclavicular cords are labeled by
their relation to the axillary artery
lateral, posterior, & medial
The infraclavicular block can be used for
lower upper arm (mid humeral shaft) and down
Describe the infraclavicular block technique.
Patient placed in supine position with their head turned to the non-operative side
transducer is placed perpendicular to the clavicle just medial to the coracoid plexus
short-axis image
cords are arranged around the axillary artery
22 gauge, 8 cm needle inserted in-plane, cephalad to caudal
incremental injection of 20-30 mLs of local anesthetic around axillary artery
For the infraclavicular block, depending on the patient’s body habitus,
a low-frequency transducer may be required
For the infraclavicular block, sliding the needle medially increases the potential for
pneumothorax & hemothorax
With the infraclavicular block, the _______ pass between the pectoral muscles so doppler may be used to prevent inadvertent puncture.
Thoraco-acromial artery & pectoral veins
With the infraclavicular block, poor needle visualization may result in inadvertent
pneumothorax/hemothorax
vascular puncture
LAST event
The axillary block is directed at the
terminal branches of the brachial plexus
The axillary block anesthetized these nerves:
axillary nerves
radial nerves
ulnar nerves
& median nerves
The axillary block is an excellent block for procedures
below the elbow
Ultrasound has made the axillary block
less attractive because other blocks can be done as efficiently with minimal complications
Describe the axillary block technique.
patient is placed in the supine position with head turned to the non-operative side, arm abducted & rotated externally
high-frequency linear array transducer is placed in the crease formed by the biceps muscle and pectoris major
22 gauge, 5 cm B bevel needle inserted in-plane
incremental injection of 20-40 mLs
With the axillary block, the _____ nerve is missed
musculocutaneous
With the axillary block, the _____ nerve is blocked first
radial nerve because of its deep location
With the axillary block, compressing the veins may
decrease the risk of vascular puncture
Complications of an axillary block include
uncommon but there is an increased risk of vascular puncture because the needle must be re-directed several times to achieve adequate LA distribution
-multiple veins located around the artery. be cautious
Paresthesia from multiple needle punctures in the axillary block may result in
neuropathy
Nerve blocks at the level of the elbow are performed as
a rescue for an incomplete block
Nerve blocks at the elbow are
localized procedures and address the radial nerve ulnar nerve median nerve -median and ulnar nerves are blocked with the arm abducted
Describe the technique used to anesthetize the median nerve.
courses alongside the brachial artery in the upper arm to the elbow- brachial artery can be verified using color doppler
needle inserted in-plane lateral to medial
following negative aspiration, inject 4-5 mL of LA
additional 2-3 mL can be injected if circumferential spread is not noted
Describe the technique used to anesthetize the radial nerve
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 4-5 mL of local anesthetic
an additional 2-3 mL may be injected if circumferential spread is not obstained
Describe the technique used to anesthetize the ulnar nerve.
scan medially to identify the medial epicondyle
scan proximal & distal along the arm to identify where the nerve enters
needle inserted in-plane, medial to lateral
following negative aspiration, inject 4-5 mL of LA
an additional 2-3 mL may be injected if circumferential spread is not obtained
The intravenous regional anesthesia is also known as
the Bier block
-may be used for upper or lower extremity procedures
Describe the bier block.
A block in which local anesthetic is injected into the venous system of an extremity that has been exsanguinated by compression & isolated by a torniquet
Describe the two mechanisms of anesthesia for the Bier block.
direct- local bathing nerve endings in the tissue
indirect- LA transported to the ‘substance’ of the nerves via the vasa nervorum
The bier block can be used for
brief surgical procedures & manipulations such as ganglion cyst excision, carpal tunnel release, Duputyren’s contractures, & fracture reduction (mostly in pediatrics)
The bier block may also be used as a treatment for
regional pain syndromes
-analgesia
reduce neurogenic inflammation
Contraindications to the bier block include
patient refusal
Relative contraindications to the bier block include
injuries to the extremity (crush or open fractures) inability to cannulate peripheral vein local skin infection or cellulitis true allergy to local anesthetics preexisting arteriovenous fistula sickle cell disease surgery greater than one hour
Describe the procedure for the bier block
- place IV catheter with as distal as possible in extremity
- apply a double pneumatic tourniquet on the proximal arm
- elevate the extremity and apply an Esmarch bandage
- occlude the axillary artery
- inflate the proximal cuff 50-100 mmHg above patient’s systolic BP
- remove Esmarch bandage
- inject 30-50 mL of 0.5-1% lidocaine
- if patient complains of tourniquet pain, inflate distal cuff first, then deflate proximal cuff
With the bier block, the tourniquet must
remain inflated for at least 30 minutes following the injection of local anesthetic, regardless of surgery length
Describe the deflation of the tourniquet for the bier block.
after 30 minutes, 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 minutes
repeat
Side effects and complications of the Bier block includes
if LE IVRA is performed, there will be 100% incidence of LA leakage under the tourniquet- observe for s/s of LAST damage to radial, median, & ulnar nerves compartment syndrome arterial thrombosis death or permanent brain damage
Regional anesthesia can result in
local anesthetic systemic toxicity (LAST)
nerve injury
intravascular puncture/injection
death
____ must be obtained prior to any regional block
informed consent
LAST most commonly occurs from
an inadvertent intravascular injection
- initial blocking of inhibitory neurons thought to cause seizures
- blocking of cardiac ion channels results in bradycardia- Vfib is the most serious complication
Shorter acting drugs are (related to LAST)
thought to be less cardiotoxic
- chemical properties play a role
- more potent agents higher lipid solubility & protein binding
The classic clinical presentation of LAST is
rapid onset, usually within a minute
The progression of subjective symptoms of last includes
agitation, tinnitus, circumoral numbness, blurred vision & metallic taste
The subjective symptoms of LAST are followed by
muscle twitching, unconsciousness, and seizures
Very high levels of intravascular LA can result in
cardiac & respiratory arrest
LAST is most commonly seen with
epidural, axillary, & interscalene
The incident rate of LAST is
0.4 per 10,000
Prevention strategies of LAST include
test dosing
incremental injection with aspiration
use of pharmacologic markers
ultrasound
Treatment of Last includes
prompt recognition & diagnosis
airway management priority
seizure suppression- benzodiazepines, succinylcholine
prevent hypoxia & acidosis
lipid emulsion therapy
vasopressors
do not give vasopressin; epinephrine <1 mg/kg
The MOA of Lipid emulsion therapy is to
capture local anesthetic in blood (lipid sink)
increased fatty acid uptake by mitochondria
interference of Na+ channel binding
promotion of calcium entry
accelerated shunting
Describe the max dose of lidocaine & mepivicaine
4 mg/kg & 7 mg/kg (with epi)
Describe the max dose of bupivacaine, tetracaine, & ropivacaine
3 mg/kg
Describe the max dose of prilocaine
7 mg/kg & 8.5 mg/kg (with epi)
Describe the max dose of procaine
12 mg/kg
Nerve injury can be either
direct needle trauma or local anesthetic toxicity
The incidence of peripheral nerve injury varies with
location
Pre-existing factors for the development of nerve injury is
diabetes, pre-existing neurologic disease, smoking, increased BMI, & male
Local anesthetic neurotoxicity is the result of
dose & concentration of LA
additive agents, e.g. epinephrine
Ultrasound allows the practitioner to identify important structures close to nerve injury including
dural
pleural
vasculature
& bowel
Patient’s perception of postoperative nerve injury can be skewed by
“postoperative blur”
non-operative factors that coincide with the surgical site
The nerve injury should be evaluated based on
presenting signs & symptoms as it could be surgical vs. insertion of block
