Upper Blocks Flashcards
is coagulopathy a contraindication to a peripheral block?
not necessarily - still have to consider potential for uncontrolled hemorrhage but compartment is compressible (vs. central blocks)
how might site infection affect a peripheral block?
might decrease efficacy of the block d/t pH of tissue being < pKa
increased ionized (hydrophilic) portion of the drug, prevents nerve entry
1 cause of LAST
inadvertent vascular injection
only block that covers the shoulder
interscalene
what area does a supraclavicular block cover?
his notes (Nagelhout) - entire upper extremity distal to the shoulder
NYSORA - anesthesia of the upper limb often including the shoulder
M&M - dense anesthesia for surgeries at or distal to the elbow
:) :) fuck :) :) this :) :)
specific risks of interscalene block
- close to carotid, vertebral artery, IJV, spinal cord, CSF
- inadvertent arterial injection = seizures
- inadvertent CSF injection = immediate high spinal
- also per M&M - almost invariably blocks ipsilateral phrenic nerve
significant risk of supraclavicular block
inadvertent puncture of pleural space & pneumothorax
+ according to M&M - nearly half have ipsilateral phrenic nerve palsy. seems important :’)
an interscalene block provides analgesia to what areas?
shoulder and upper arm
infraclavicular block provides analgesia to what areas?
elbow and below
axillary block provides analgesia to what areas?
distal to elbow
3 approaches for peripheral nerve blocks
- US guided
- peripheral nerve stimulation
- landmark (blind)
skin prep used prior to nerve block
chlorhexidine and alcohol mixture
(betadine considered neurotoxic)
local analgesia used prior to nerve block
0.5-1 mL of 1% lidocaine using a 27g or 30g needle to block insertion site
lead placement for peripheral block via nerve stimulation
- positive (red): connected to electrical attachment of nerve-stimulating needle
- negative (black): connected to EKG sticker
*note that he said what’s on his handout is mislabeled*
what shape needle is used for a nerve block?
conical shape - reduces likelihood of impaling the nerve by displacing rather than peircing the fiber
what aspect of block needle design allows you to recognize the tip based on muscle tip response?
needles have an insulating property designed to transfer electrical stimulus to the tip of the needle rather than along the full length
target range for satisfactory muscle response when doing a peripheral block via nerve stimulation
0.3 - 0.5 mA
if muscle contraction is occurring at < 0.3 mA, what does that mean?
too close to the nerve/may be in contact with it
pull the needle back before injecting LA
benefits of ultrasound-guided peripheral blocks
- more precise placement
- more complete and dense block
- avoid adjacent structures
- reduce intravascular injection risk
cross sectional US view - short axis or long axis?
short axis
longitudinal US view - short axis or long axis?
long axis
US view used to identify the anatomy of the nerve and center it on the screen
short axis (cross section)
advantage of long axis US view of needle
full view of needle is maintained throughout
decreased chance that needle tip is lost “out of plane”
which US view is described:
if standing at the side of a tunnel, you can see length but can’t appreciate width
long axis
which US view is described:
if you were looking down through a train tunnel and have a view of the outside edge and hole where the train comes through
short axis
(no quantifiable depth)
where is the beam emitted by the US probe
only directly under the probe
nerves that make up the brachial plexus
C5-T1
elements of the brachial plexus
(idk how else to ask this)
Roots
Trunks
Divisions
Cords
Branches
Real Texans Drink Cold Beer
which brachial plexus block approach blocks trunks?
interscalene
which brachial plexus block approach blocks divisions?
supraclavicular
which brachial plexus block approach blocks cords?
infraclavicular
which brachial plexus block approach blocks branches?
axillary
nerve of brachial plexus that is typically not covered by interscalene block
ulnar nerve
volume of injection for brachial plexus block
commonly ~30 mL
pneumothorax is a risk for all brachial plexus block approaches except:
axillary
complication of brachial plexus block that is related to close proximity to phrenic nerve
for which patients is this particularly problematic?
ipsilateral hemiparesis of diaphragm
problematic in pts with compromised spontaneous ventilation
treatment for ipsilateral diaphragm hemiparesis with brachial plexus block
none - self limiting
typically not noticable in young, healthy pts
what is Horner’s syndrome?
uptake of LA into head and neck that results in sympathetic blockade to nerves affecting facial structures
symptoms and treatment of Horner’s syndrome
S/S: ptosis, miosis, anhidrosis on affected side
self-limiting for duration of block
block that is well-correlated with Horner’s sydnrome
interscalene
how to locate point of injection for interscalene block
- identify sternal head of sternocleidomastoid muscle
- move laterally to clavicular head
- move further lateral to space in between anterior and middle scalenes
adverse effect of using only the landmark technique for axillary block
puncture of axillary artery
nerve that is closest to US probe and skin (superficial) in the axillary approach
median nerve
location of median nerve in axillary approach
- superficial
- adjacent to coracobrachialis muscle
- anterior
axillary approach:
deepest nerve (opposite the median nerve)
radial nerve
axillary approach:
nerve that is on the biceps side
musculocutaneous
axillary approach:
nerve that is on the triceps side
ulnar nerve
when should epi be avoided in an upper extremity block?
below the elbow
(risk of vasculature compromise generally outweighs use)
general volume max for ulnar nerve blocks
(or did he mean all upper extremity blocks? per nerve with brachial plexus blocks? this is incredibly confusing)
5 mL
max surgical time for a Bier block
2 hours
where is the IV placed for a Bier block?
in operative extremity, as distal as possible
(will be removed after LA injection - will need a separate IV for anesthesia purposes)
how long does a tourniquet have to be left inflated for a Bier block?
why?
at least 20 min
to prevent toxicity - after 20 min, enough of LA has absorbed into soft tissue and will be metabolized when released back into vasculature
when does tourniquet pain become as prominent as surgical pain?
> 2 hours
contraindications for a Bier block
- severe compromise of venous system, soft tissue trauma (need an intact venous compartment)
- arm has to be able to tolerate arterial tourniquet - AV fistula, mastectomy
contraindications for a Bier block
- severe compromise of venous system, soft tissue trauma (need an intact venous compartment)
- arm has to be able to tolerate arterial tourniquet - AV fistula, mastectomy
additives to a Bier block
- any agent that would otherwise be acceptable for IV admin
- common: clonidine, toradol, ketamine, decadron, fentanyl
chronology of Bier block (9)
- place small gauge IV in operative extremity
- place tourniquet on upper arm (or leg) after padding in place
- note radial pulse
- elevate arm
- esmarch bandage exsanguination
- inflate tourniquet 50 mmHg over SBP
- confirm absence of pulse
- inject 50mL of preservative free 0.5% lidocaine without epi
- remove IV
LA used for Bier Block
50mL preservative-free 0.5% lidocaine without epi
why can’t you use 1% lidocaine for a Bier Block?
would have to use less volume to prevent toxicity and you need that volume to fill the compartment
where must the tourniquet be placed for a Bier Block (upper extremity)?
on the humerus - incidence of failure higher on forearm d/t 2 bones being in the way
why is double tourniquet for a Bier block used
allows a field block to occur naturally
addresses tourniquet pain
technique of a double tourniquet for Bier block
- inflate proximal tourniquet at the beginning of the case
- when tourniquet pain develops, distal tourniquet inflated (over an area that is numb)
- after distal inflation, proximal tourniquet deflated
methods to avoid soft tissue injury with Bier block
cast padding or equivalent under tourniquet
descending order of vessels and nerve in the inferior border of the rib
vein
artery
nerve
functions of the radial nerve
- triceps
- supination of forearm
- extension of wrist
- abduction of thumb
- extension of other fingers
function of median nerve
- flex elbow
- pronate forearm
- flex wrist
- flex fingers
- abduct thumb
what nerves form the radial nerve
C5-T1
what forms the median nerve
lateral and medial cords
nerves that form the ulnar nerve
C8-T1
functions of ulnar nerve
- flexion of wrist, ring, and small (pinky?) fingers
- adduction of fingers
- adduction & flexion of thumb
use of intercostal block
- lasts several hours
- reduce surgical pain
- allow improved efficacy of painful respirations
landmark for intercostal block
midaxillary line
adverse effect of particular concern with an intercostal block and why
LAST
LA uptake is highest with intercostal block
(also PTX, but some others can cause that too)
why might epi be added to an intercostal block?
to reduce vascular uptake & risk of LAST
technique for intercostal block
- find rib with needle and slide to inferior edge
- pass inferior edge 2-3 mm before injection
block that provides analgesia to abdominal compartment
TAP block
(transversus abdominus plane)
uses of TAP block
open and laparoscopic procedures
post-op pain
in a TAP block, LA spreads between what 2 muscles?
internal oblique & transversus abdominus
what does a TAP block cover?
unilateral blockade of nerves from T9-L1
volume used in a TAP block
20 mL injected incrementally under US guidance
limitations of TAP block
can have inadequate spread through fascial plane
muscle or sub-q uptake can impact duration and levels affected
what indicates an appropriately placed TAP block on US?
separation of the plane between internal oblique and TA muscle
what are these things if your US probe is on a tummy
- Subq
- external oblique
- internal oblique
- transversus abdominus
- abdominal content
risks of a thoracic epidural
- infection
- bleeding
- hypotension
- bradycardia
common approach for thoracic epidural
paramedian
where is LA injected for a pec nerve block?
between pec major and minor
where is US placed to find location of pec block?
at origin of pec muscle near anterior axillary line
identify musles in SAX
landmark for paravertebral block
identify transverse process at target level (generally several levels injected)
technique for paravertebral block
- identify transverse process at target level
- insert spinal/epidural needle to transverse process and “walk off” to an additional 1cm depth
- generally 5mL LA per level
onset and duration expected with paravertebral block
uptake fairly rapid
4 hour duration of effective analgesia expected
erector spinae plane block vs. paravertebral and PEC blocks
markedly simpler
less risk
higher success rate
what is responsible for increasing spread and absorption into spinal nerves in an erector spinae block?
volume
nerve root that typically corresponds with the radial nerve
C6
nerve root that typically corresponds with the median nerve
C7
nerve root that typically corresponds with the ulnar nerve
C8
Label A-F on this beautiful textbook worthy graphic
A: radial (C6)
B. median (C7)
C. ulnar (C8)
D. medial cutaneous
E. axillary
F. musculocutaneous
T/F Bupivacaine can be used for a bier block
Nope never
Which nerve is generally the most hyperechoic in axillary view?
Musculocutaneous
3 muscles identified for a TAP block
(worksheet)
- external oblique
- internal oblique
- transversus abdominus
the red represents sensory distribution of what brachial plexus block approach?
interscalene
the expected sensory distribution of which brachial plexus block approach is shown
supraclavicular
(note: does not reliably anesthetize the axillary nerve/shoulder area)
left is lateral, medial is right
what are these things
(worksheet 4)
- brachial plexus trunks
- SCM
- carotid artery (left)
What nerve lies separate from the axillary artery that must be blocked separately for terminal branch coverage?
(worksheet)
musculocutaneous
what are these circled guys?
(this is a right sided supraclavicular approach to brachial plexus)
brachial plexus divisions
(lateral to artery)
what are these things in the right groin
(left is medial, right is lateral)
- femoral vein
- femoral artery
- femoral nerve
