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REGIONAL ANESTHESIA: IN A FEW SHADES OF GREY

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Holly Franson

on 23 October 2015

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Transcript of REGIONAL ANESTHESIA: IN A FEW SHADES OF GREY


OBJECTIVES
Review pertinent anatomy for upper and lower extremity peripheral nerve blocks

Discuss indications for commonly performed upper and lower extremity peripheral nerve blocks including: interscalene, supraclavicular, femoral, and adductor canal blocks

Define the common steps in performing ultrasound guided nerve blocks

Identify and define ultrasound anatomy

Discuss the basic principles of ultrasound imaging and machine operation

Review complications and management of commonly performed peripheral nerve blocks

BRACHIAL PLEXUS BLOCKS
Approach is dependent on surgical site, patient's co-morbidities and psychological state, risk of complications, contraindications, and experience of anesthesia provider
Common brachial plexus blocks:
INTERSCALENE AND SUPRACLAVICULAR

INTERSCALENE BLOCK
Blocks nerve
ROOTS
at interscalene groove
Intense C5-C7 block
Less intense C8-T1 (Ulnar nerve)-Not good for hand surgery
Variable proximal spread to cervical plexus (C3-5)

PERIPHERAL NERVE BLOCKS:

IN
A

FEW

SHADES
OF
GREY

Holly Franson CRNA, MSN
John D. Dingell VAMC
Detroit, MI

BENEFITS OF REGIONAL ANESTHESIA
Reduced opioid requirement
Improved intraoperative analgesia and anesthesia
Excellent postoperative analgesia
Decreased time until discharge
Less need for hospitalization
Lower healthcare costs
Improved patient satisfaction and outcomes
Early physical activity
Hemodynamic stability
Reduced side effects
Avoidance of airway instrumentation


Benefits of regional anesthesia
Avoid airway manipulation
Reduced PONV
Improved pain control
Rationale for using ultrasound technique
Complications, prevention, and management
General preoperative, intraoperative, and postoperative procedures

BRACHIAL PLEXUS
ANATOMY

A thorough understanding of anatomy, basic principles, proper technique, and practice can produce excellent success rates with minimal complications

“Anatomy is the foundation
upon which the entire concept of regional anesthesia is built”
Labat

ANATOMY

At least 29 variations of BP exist
2/3 of the population have different BP configurations from left to right side

BP arises from ventral (anterior) primary rami of
C5-T1
spinal nerve
ROOTS
Occasional contribution from
C4 or T2

ROOTS (5)
exit in the trough of the cervical transverse process
Posterior to the
VERTEBRAL ARTERY

ROOTS (5)
emerge between anterior and middle scalene muscles-
INTERSCALENE GROOVE

Brachial plexus surrounded by prevertebral fascia- forming
“BRACHIAL PLEXUS SHEATH"

C5-C6 NERVE ROOTS
C7 NERVE ROOT
C8-T1 NERVE ROOTS
C5-T1 nerve
ROOTS (5)
converge into
3

TRUNKS-
Superior (C5-C6)
Middle (C7)
Inferior (C8-T1)

SUPERIOR, MIDDLE, INFERIOR TRUNKS
Superior, Middle, Inferior
TRUNKS (3)
pass under the
clavicle
and over the
1st rib

Joined by the subclavian artery
Together the
TRUNKS (3)
and
subclavian artery
form a neurovascular bundle

TRUNKS (3)
(Superior, Middle, Inferior) divide into anterior and posterior
DIVISIONS (6)
3 Anterior (ventral)
3 Posterior (dorsal)
Divisions formed at lateral edge of first rib


DIVISIONS (6)
form
3

CORDS
Lateral
Medial
Posterior
Named in relation to axillary artery

3 CORDS
(lateral, medial, posterior) form
TERMINAL nerves
at the level of the axilla (lateral border of the pectoralis minor)

Musculocutaneous
Median
Ulnar
Axillary
Radial

Musculocutaneous
Sensory distribution-brown (skin over lateral forearm)
Motor-Flexion at elbow (biceps contraction)

Median
Arises from
medial
and
lateral

cord
Sensory and motor fibers
Sensory: palmar surface of the hand, first 3 fingers, half of 4th finger
Motor: flexor muscles of the forearm/hand

Median
Sensory distribution-Pink (skin over anterolateral surface of hand)
Motor- Flexion of wrist and opposition of middle, forefinger, thumb

Ulnar
Sensory distribution-Green (skin over medial surface of hand)
Motor- Flexion of wrist/flexion and opposition of medial 2 fingers towards thumb

Axillary

Arises from
posterior

cord
Sensory and Motor fibers
Sensory: posterior shoulder and arm
Motor: deltoid and teres muscle

Axillary
Sensory distribution-Yellow (part of skin over shoulder)
Motor-Shoulder abduction (deltoid contraction)

Radial
Sensory distribution-Blue (skin over posterolateral surface of arm)
Motor- Extension of elbow, supination of forearm, extension wrist and fingers

Intercostobrachial nerve (T2)
Not a part of BP
Lateral branch of second intercostal nerve
Supplies sensory innervation to axilla and upper posterior medial side of the arm

ULTRASOUND:
ADVANTAGES

Real

time
visualization of target nerves, arteries, veins, muscle, bones, and needle
Avoid vascular structures & accurately inject LA (avoids intravascular and intraneural injection)
LA injection is visualized to ensure adequate spread
Provides imaging guidance of needle advancement allowing purposeful needle movement and proper adjustments

Improves quality of block, decreases onset time, and has shown higher success rate compared to nerve stimulator alone
May allow for less LA volume
Reduces number of needle attempts
No radiation, relatively simple to learn, moderately priced
Fewer complications compared to nerve stimulator

Needle tip observation may be hindered by poor technique or echogenic characteristics
Resolution may not be able to differentiate between intrafascicular vs. extrafascicular needle tip location
Use may be limited by cost and educational needs
Image limited by obesity

ULTRASOUND:
DISADVANTAGES
ULTRASOUND
Ultrasound is a form of
mechanical sound energy
that travels through a conducting medium as a longitudinal wave of pressure changes. The pressure variations produce alternating compression (high pressure and amplitude) and rarefaction (low pressure and amplitude).

Frequency:
Number of cycles per second
Hz is basic unit for specifying frequency
Inverse of a wavelength (higher frequency = shorter wavelength)

Wavelength :
Length of space between two consecutive peaks or troughs of a sound wave

ULTRASOUND
ULTRASOUND IS HIGH FREQUENCY SOUND
“Ultrasonic” involves sound waves with a frequency above the upper limit of human hearing >20,000 Hz
Human hearing is in the 20-20,000 Hz range
Medical ultrasound is normally in the 2 MHz to 15 MHz range (2.0-15 million cycles per second)

Ultrasound waves are created when an electric field is applied to an array of piezoelectric crystals located in the ultrasound transducer
This electrical stimulation causes mechanical distortion of the crystals resulting in vibration and the creation of sound waves
(mechanical sound energy)


The pulse wave (sound wave) released from the transducer is transmitted into the body and reflected off tissue
The transducer waits to receive the returning sound wave (echo) after each pulse wave is emitted

The transducer then converts the echo
(mechanical energy)
into an electric signal
This
electric signal
is then displayed as an image on the screen...IN...

Ultrasound travels into the body and interacts with various body tissues
The beam becomes
attenuated
(energy loss) related to:
Absorption (conversion of acoustic energy to heat)
Scattering
Transmission
Refraction
Reflection

Scattering:
Diffuse reflection
Transmitted wave encounters surface that is not perfectly smooth or small
Returning echoes weaker than with reflection as they are deflected toward and away from the probe

A few shades of Grey...
B. Transmission:
Transmitted wave continues through tissue

C. Refraction:
Directional change of transmitted beam related to change of sound between two tissues
Results in image distortion
D. Specular reflection:
Transmitted wave is reflected in a
single direction
depending on angle of incidence
An ultrasound wave hitting a smooth, flat surface at 90 degrees creates a perpendicular refection


Image produced by ultrasound is influenced by the amount of beam returning to the transducer (reflection) after encountering the target structure

Degree of brightness of an ultrasound image is
ECHOGENICITY
, influenced by the amount of beam returning to the transducer (reflection) after encountering the target structure
Whiter objects represent a larger degree of reflection and higher signal intensities
Darker objects represent less reflection and weaker signal intensities

ULTRASOUND
Hyperechoic structures:
Image characteristic of a structure that is very reflective creating a
BRIGHTER
displayed image compared to adjacent structures
“white” on screen

Hypoechoic structure:
Image characteristic of a structure that is less reflective than the surrounding structure creating a
DARKER
displayed image compared to the adjacent structures
“grayish-black” on screen
Anechoic structures:
No reflection, ultrasound waves pass easily through structures without much reflection
“black” on screen
ULTRASOUND IMAGES
V= vein
Lumen= Anechoic
Oval
Compressible


A= artery
Lumen= Anechoic
Round
Pulsitile
Fat:
Hypoechoic with irregular hyperechoic lines

Muscle:
Heterogeneous (hypoechoic background with short hyperechoic lines)
Fascial sheath= hyperechoic

Bone:
Hyperechoic line with hypoechoic bony shadow

Nerve:
Low interscalene and supraclavicular area
Generally hypoechoic
Hypoechogenicity represents neural tissue

Nerve:
Inferior to the clavicle and lower limbs generally hyperechoic with honey comb look
Hyperechogenicity reflects amount of connective tissue in the nerve
ULTRASOUND: Hyperechoic
ULTRASOUND: Hypoechoic
OPTIMIZING AN ULTRASOUND IMAGE
Resolution (Frequency):
Ability to distinguish between two structures that lie adjacent to one another



CLINICALLY
:
High frequency probe provides better resolution and the ability to distinguish between adjacent neural structures
High frequency probes have increased attenuation and are unable to penetrate into deep tissue
Strike a balance between attenuation and resolution!

Focus:
Lateral resolution may be improved by reducing the width of the beam and choosing the highest frequency transducer
Beam diverges at far field

Place focal zone at, or slightly below target structure to produce best lateral resolution and optimize image quality
Choose appropriate transducer frequency

CLINICALLY
Gain:
Gain control offsets attenuation (reduction in sound amplitude) as sound waves travel through tissue
Transducer may amplify returning signal creating a brighter image
Under gain = image too dark
Over gain = image too bright


CLINICALLY
:
Adjust overall gain or time gain compensation (TGC) to increase or decrease image brightness
Appropriate Gain

Under Gain
(Dark Image)
Over Gain
(Bright Image)
Depth control:
set a tissue depth in cm that ultrasound waves will penetrate

FIELD DEPTH:
< 2
2-3
3-4
4-7

PNB:
WRIST/ANKLE
INTERSCALENE/AXILLARY
FEMORAL/SUPRACLAVICULAR
POPLITEAL/ADDUCTOR


Doppler:
Allows for differentiation of structures containing moving fluid
CLINICALLY:
Used to detect vascular structures or spread of LA
Depth (cm):

Consider recommended depth for block
Patient body habitus
Target nerve at center of image for best resolution and identification of surrounding anatomy

PROBE SELECTION
Shape
and
frequency
control ultrasound image

Linear transducer optimal for superficial anatomy

Curved (curvilinear) generally better for deeper structures

Frequency:
Transducers used for PNBs typically range from 2-15MHz
Goal is to select highest frequency transducer for depth of penetration

Higher frequency probes (>7MHz)- provide images with greater resolution but do not penetrate deeply
Ideal for superficial structures (interscalene and supraclavicular regions)
<4 cm deep

Lower frequency probes (<7MHz)- penetrate deeply but the resolution is less
May be needed for deeper structures (popliteal region)
>4 cm deep
ART + P (Pressure)
Alignment:
Sliding transducer longitudinally to evaluate course of needle or target structure

Rotation:
Rotating transducer clockwise/counter-clockwise
Important to align ultrasound beam, needle, and nerve

Tilting:
Tilting/angling transducer to improve image by aligning beam perpendicular to target

NEEDLE INSERTION TECHNIQUES

In-plane
Needle inserted in ultrasound beam
Entire shaft and tip observed in real time

Out-of-plane
Needle inserted perpendicular to ultrasound beam
Tip visualized as a bright white dot on image

Frequency:
Select transducer with optimal frequency range and shape
High frequency probes provides better resolution yet increased attenuation
Gain:
Offsets attenuation by adjusting screen brightness
Adjust screen brightness by gain control and time-gain compensation manipulation
Doppler:
Used to identify vascular structures or spread of local anesthetics

INTERSCALENE
Indications:
Shoulder
, upper arm, humerus surgery (rotator cuff repair, total shoulder replacement, reduction of shoulder dislocation, creation of upper extremity arteriovenous fistula)
Supraclavicular nerves anesthetized
Forearm surgery- not recommended with classic approach

Patient selection:
Appropriate for most patients, superficial and easy to perform
Caution in patients with severely impaired pulmonary function related to phrenic nerve paralysis
Combination with general anesthetic reduces risk as phrenic nerve function should be adequate by end of surgical procedure.

SUPRACLAVICULAR
Roots emerging between anterior and middle scalene muscles
(AKA-interscalene groove)

INTERSCALENE BLOCK:
EQUIPMENT
Sterile towels/gauze packs
Sterile gloves
2- 20 ml syringes with LA
3 ml syringe with 25 G needle or TB syringe for LA
2 inch/22 G insulated stimulating needle
+/- PNS
Marking pen
*Some facilities have standard block trays
US machine with high frequency linear transducer
Gel

INTERSCALENE BLOCK:
Pharmacologic choice
Lidocaine (1-1.5%)
Without epi 2-3 hours surgical anesthesia
With epi 3-5 hours surgical anesthesia
Mepivacaine (1-1.5%)
Without epi 2-3 hours surgical anesthesia
With epi 3-5 hours surgical anesthesia
Bupivacaine (0.5%)
Without epi 4-6 hours surgical anesthesia
With epi 8-12 hours surgical anesthesia
Ropivacaine (0.5-0.75%)
Similar to bupivacaine with slightly shorter duration

INTERSCALENE BLOCK: ULTRASOUND TECHNIQUE
Supine/semi-sitting/semi-lateral decubitus
Head turned to contralateral side

Identify Landmarks:
Cricoid cartilage (C6)
Sternocleidomastoid (posterior border of clavicular head)
Interscalene groove
EJ (generally crosses interscalene groove at level of trunks)

White arrows= clavicle
Red arrows= posterior border of SCM
Blue arrow= EJ

Helpful hints to palpate interscalene groove
Accentuate the SCM- Ask patient raise their head and feel the posterior border of the clavicular head of sternocleidomastoid muscle at C6 (cricoid cartilage), roll fingers laterally to anterior scalene muscle, then feel the groove lateral to that.
Accentuate the EJ- Ask patient to do a valsalva maneuver. EJ frequently crosses the groove at C6. Needle posterior to EJ
Accentuate interscalene groove- Ask patient to sniff forcefully. Tenses scalene muscles and fingers often roll into groove

Needle insertion point:
Classic teaching: Interscalene groove at C6
Newer technique “Low interscalene technique” - 3-4 cm above clavicle.

Skin and transducer prep
Use
linear, high frequency 8-14 MHz

transducer
and gel
Choose appropriate depth:
2-3 cm
Transverse orientation of transducer on neck

Goal: Scan to identify scalene muscles and nerve roots between
Adjust focus and gain to obtain best image

Place probe in transverse plane at level of cricoid cartilage medal to SCM to identify carotid artery. Scan laterally. Identify scalene muscles and BP between.

Place transducer at level of supraclavicular fossa. Identify BP, lateral to subclavian artery. Trace cephalad to desired position.
Nerve roots appear
hypoechoic
, round or oval
Hypoechoic- image less reflective the surrounding structures, resulting in a darker image
Nerves are between anterior and middle scalene muscles
IJ and carotid artery are medial


In plane (lateral to medial direction)
2 inch, 22 G insulated needle on lateral end of US transducer towards
roots
Pass through
prevertebral fascia
May confirm with electrical stimulation
Negative heme aspiration before and during LA injection
Inject 15-40 ml of LA
Volume dependent on adequacy of LA spread around nerves
LA is hypoechoic

INTERSCALENE BLOCK:
COMPLICATIONS
Phrenic nerve block (C3-5)
Unavoidable effect (100%)
Reduces pulmonary function by 25-33%
Related to:
Direct contact of LA with phrenic nerve as it crosses the ASM
Cephalad spread of LA to C3-C5
Causes diaphragmatic paralysis
Avoid block in patients with:
Severe chronic respiratory disease (especially restrictive disease)
FVC < 1L
Contralateral diaphragm or phrenic nerve dysfunction, pneumonectomy
Breathing with the use of accessory muscles as it may lead to respiratory failure
Use smaller volume of LA (??)
Most literature supports that manipulation of LA type, dose and concentration has little influence on pulmonary function after block

Horner’s Syndrome (Stellate ganglion block)
Related to cervicothoracic sympathetic trunk in close proximity to lower BP
Ptosis, anhydrosis, miosis, nasal congestion
Educate patient and reassure symptoms will fully resolve
Less likely with "low" interscalene technique

Accidental epidural (cervical epidural anesthesia) , subarachnoid (total spinal), subdural injection
Distance from skin to intervertebral foramen may be as little as 25 mm and 35 mm to neuraxis
Consider shorter needle and use fractionated dosing
PRESENTATION?!?

Pneumothorax-small risk
Symptoms generally delayed 10-12 hours
Outpatient??
Higher risk with hyperinflated lung (smoking)
Common symptom: Pleuritic chest pain

Infection
Very low risk
Maintain aseptic technique

Hematoma
Avoid needle insertion through EJ
Avoid multiple needle sticks

Vascular puncture
Apply steady pressure for 5 min if carotid punctured
Nerve injury*
Never inject at a pressure > 15 psi
Stop injection if patient complains of severe pain or withdrawal reaction on injection

Unilateral Recurrent Laryngeal Nerve Block
Hoarseness/ vocal cord dysfunction
Educate patient and reassure symptoms will fully resolve with dissipation of LA block

LOCAL ANESTHETIC TOXICITY
PREVENT YET PREPARE!
Usually manifests
during or shortly after
procedure
Avoid large volumes of long acting LA in frail/elderly patients, those with poor cardiac function, conduction abnormalities, or low plasma proteins
Careful aspiration
Avoid fast, forceful injection

Systemic toxicity (LAST):

Clinical symptoms:
Due to excessive dose with fast absorption
Due to intravascular injection

Factors influencing plasma concentration:
Dose of drug administered
Rate of absorption of the drug
Site injected, vasoactivity of drug, use of vasoconstrictors
Biotransformation and elimination of drug

Early signs:
Blockade of inhibitory pathways in cerebral cortex likely accounts for excitatory phase
Subjective symptoms:
Lightheadedness, dizziness
Numbness of tongue
Difficulty focusing
Tinnitus
Confusion
Objective symptoms:
Shivering, tremors, myoclonia, muscular contractions

Later signs:
Tonic clonic convulsions as LA level increases
Coma
Respiratory depression/arrest
Cardiac arrest

Acid-base status:
Avoid acidosis and hypercarbia
Amplify CNS effects of toxicity at worsen cardiotoxicity
Reduces binding of LA by plasma proteins resulting in more free drug available for diffusion
Hypercarbia:
Enhances cerebral blood flow making more LA accessible to cerebral circulation
Carbon dioxide also crosses the nerve membrane causing intracellular acidosis
Acidosis causes intracellular ion trapping promoting the conversion of LA into active cationic form

Prevention:
Key to safe practice!
Patient evaluation
Permits individualization of LA dose
Full monitors
Premedication:
Benzo pre-treatment can lower probability of seizures, but mask early signs of toxicity
Equipment:
Oxygen, suction, airway equipment and drugs readily available and functioning
Functioning IV
Drugs
Anesthetic and resuscitate drugs available
Double check dose
Aspirate every 5 cc’s
Monitor cardiovascular signs
Epinephrine as vascular marker (5-15 mcg)
Positive signs are increased heart rate > 10 bpm or increase in systolic BP > 15 mmHg
Verbal communication with patient

Treatment:
EARLY RECOGNITION AND STOP LA
HELP AND CALL FOR 20% LIPID EMULSION
AIRWAY AND BREATHING
Clear airway if needed (suction) and hyperventilate with 100% oxygen
CIRCULATION
Elevate legs, increase IV fluids if hypotensive, CVS support with persistent hypotension
DRUGS
Anticonvulsant
Midazolam 0.075-0.15 mg/kg IV
Propofol 1-20 mg/kg IV
NOT a substitute for interlipid. Small doses may help control seizures.
CVS SUPPORT
Treat arrhythmias with standard cardiopulmonary resuscitation protocols
Evidence suggests avoiding:
Ca channel blockers, phenytoin
increases mortality
Epi controversial
may induce dysrhythmia or exacerbate arrhthymia
Consider vasopressin

Early initiation of intralipid (preventative):
Bolus Intralipid 20%
1.5 ml/kg
over 1 minute
Infusion of Intralipid at
0.25 ml/kg/min
Chest compressions (circulate drug)
Repeat bolus q 3-5 minutes up to 3 ml/kg total dose until circulation is restored
May continue Intralipid infusion until hemodynamically stable
Max recommended dose 8 ml/kg

OXYGENATION AND VENTILATION IS EXTREMELY IMPORTANT AS HYPOXIA, HYPERCARBIA, AND ACIDOSIS POTENTIATES THE NEGATIVE INOTROPICC AND CHRONOTROPIC EFFECTS OF LA TOXICITY

Indications:
Any surgery of arm distal to shoulder
Elbow replacement, creation of AV fistula, treatment of fractures, dislocations, abscesses of upper extremity

Patient selection:
Appropriate for most patients
Caution in uncooperative patients
Landmark technique may be difficult in obese patients
Pneumothorax risk with surface based landmark technique

SUPRACLAVICULAR BLOCK
Performed at the level of the distal TRUNKS and beginning of DIVISIONS
Anesthetizes C5-T1

The “spinal anesthetic” of the upper extremity!

BP is most compact here (smallest surface area)
Provides best anesthesia with a single injection- rapid/dense block
Superficial and comfortable for patient
Requires relatively small amount of LA

SUPRACLAVICULAR BLOCK:
EQUIPMENT
Sterile towels/gauze packs
Sterile gloves
2- 20 ml syringes with LA
3 ml syringe with 25 G needle or TB syringe for LA
2 inch/22 G insulated stimulating needle
+/- PNS
Marking pen
*Some facilities have standard block trays
US machine with high frequency linear transducer
Gel

SUPRACLAVICULAR BLOCK:
PHARMACOLOGIC CHOICE
Lidocaine (1-1.5%)
Without epi 2-3 hours surgical anesthesia
With epi 3-5 hours surgical anesthesia
Mepivacaine (1-1.5%)
Without epi 2-3 hours surgical anesthesia
With epi 3-5 hours surgical anesthesia
Bupivacaine (0.5%)
Without epi 4-6 hours surgical anesthesia
With epi 8-12 hours surgical anesthesia
Ropivacaine (0.5-0.75%)
Similar to bupivacaine with slightly shorter duration for surgical anesthesia
Ropivacaine 0.2% with 1:300,000 epi for analgesia

Performed at level of distal
TRUNKS/DIVISIONS
where BP passes under clavicle and over first rib
Between anterior and middle scalene muscles insertion into first rib
BP is lateral, posterior and cephalad to the subclavian artery
Subclavian vein and anterior scalene muscle are medial to subclavian artery

BP passes under clavicle and over first rib
Between anterior and middle scalene muscles insertion into first rib
BP is lateral, posterior and cephalad to the subclavian artery.
Subclavian vein and anterior scalene muscle are medial to subclavian artery.

Pleural dome in concavity of first rib
Located primarily in medial third of clavicle
(same location SCM inserts on clavicle)

The sternocleidomastoid muscle inserts on the medial third of the clavicle (coinciding with pleural dome)
The trapezius inserts on the lateral third
The neurovascular bundle passes underneath the middle third, which includes the midpoint of the clavicle

DIVIDE CLAVICLE INTO THIRDS
is the injection of LA around the brachial plexus lateral to the subclavian artery

SUPRACLAVICULAR BLOCK: ULTRASOUND TECHNIQUE

Gather equipment
Supine, semi-sitting, semi-lateral position
Head rotated to contralateral side
Identify anatomy
Interscalene groove
Clavicle
Subclavian artery

Obtain view of subclavian artery and BP (TRUNKS/DIVISIONS)
May slide or tilt transducer to obtain optimal view of artery
Consider using doppler
Adjust focus and gain to obtain best image

Nerves appear
hypoechoic
(DARKER), round or oval (“grapes”)
Nerves are lateral and superior to pulsatile
subclavian artery
(hypoechoic) and superior to 1st rib
First rib can be seen as a linear hyperechoic structures deep to artery
Parietal pleura is a linear hyperechoic structure seen deep to artery and lateral and medial to the first rib

Rib
White arrows= fascial sheath
Parietal pleura
Deep to the artery and BP:
First rib is linear hyperechoic structure
Parietal pleura is a linear hyperechoic structure seen lateral and medial to the first rib with lung tissue below it
Rib is an osseous structure and casts a acoustic shadow.
Deep structures appear anechoic (dark)

In plane (recommend)
2 inch 22 G insulated needle on outer/lateral end of transducer (lateral to medial direction)
Advance needle in same plane as ultrasound beam
Often feel “pop” as paravertebral
May confirm with electrical stimulation
Negative heme aspiration before and during LA injection
Inject LA (20-40 ml), watch spread- generally 20-25 ml of LA appropriate

Improper injection of hypoechoic local anesthetic (LA) spread outside the brachial plexus sheath.

Proper injection of hypoechoic LA inside the expanded brachial plexus sheath.

SUPRACLAVICULAR BLOCK: COMPLICATIONS
Pneumothorax (1-6%)
S & S- cough and SOB
Most feared complication!
Lower risk with US guidance

Hemothorax

Horner’s Syndrome

Phrenic Nerve Block
Neurologic complications

LOWER EXTREMITY REGIONAL ANESTHESIA
Advantages:
Avoid sympathectomy associated with spinal
Avoid general anesthesia in high risk patients
Little effect on hemodynamic status
Appropriate for patients with head injury, CV instability, localized infection (spine)
Early ambulation
Perioperative and postoperative pain relief
Reduced nausea and vomiting
Continuous infusion catheter

Disadvantages:
Time consuming
Failure (up to 5% in the best hands)
Mobilization
of patient to position for block may be difficult due to co-morbidities (obesity, arthritis, fractures)
Nerves not as compact compared to brachial plexus
Nerves cannot be blocked with single injection
Many providers not as comfortable with techniques due to ease of blocking lower extremities with neuraxial techniques

LOWER EXTREMITY
ANATOMY

Nerve supply to lower extremity is from 2 plexuses:
lumbar plexus and sacral plexus (lumbosacral)
L1-S3

Lumbar plexus primarily innervates ventral part of LE
Sacral plexus primarily innervates dorsal part of LE
ANATOMY:
LUMBAR PLEXUS

Lumbar Plexus
Anterior (ventral) rami of L1-L4 (occasional T12 contribution) form lumbar plexus

Formed by anterior rami
of L1-L4
Formed within
psoas major muscle
Lumbar Plexus
has 6 main peripheral
branches

Lumbar Plexus (Cephalad Branches)
Iliohypogastric Nerve-L1
Ilioinguinal Nerve- L1
Gentiofemoral Nerve-L1-L2

Lumbar Plexus (Caudal Branches)
Lateral Femoral Cutaneous Nerve (LFC)- L2-L3
Femoral Nerve- L2-L4
Obturator Nerve- L2-L4

Lateral Femoral Cutaneous (L2-L3)
Emerges lateral to psoas muscle and courses deep to iliac fascia and anterior to iliacus muscle
Emerges from fascia medial to ASIS
Passes under lateral end of inguinal ligament
Courses superficial or deep to Sartorius muscle traveling under fascia lata
Purely Sensory innervation to lateral thigh

LFCN has a very variable course!

Femoral Nerve (L2-L4)
Passes under inguinal ligament lateral to femoral artery
Supplies muscle and skin of anterior thigh, knee, hips
Saphenous nerve is purely sensory branch of femoral nerve

Femoral Nerve covers skin of anterior thigh, knee, hips .
Largest terminal branch of lumbar plexus.

Dermatomes anesthetized
in dark blue
Obturator Nerve (L2-L4)
Descends towards pelvis on medial boarder of psoas muscle
Exits pelvis through obturator foramen
Innervates adductor muscles of thigh, hip, knee joints, & skin medial to thigh

ANATOMY:
SACRAL PLEXUS

Sacral Plexus
Anterior rami of L4-L5 & S1-S3 (some sources S4)
Major nerve:
Sciatic (L4-S3)

Anterior rami of L4-L5 & S1-S3 (occasionally S4)
Sciatic Nerve (L4-S3)
Largest nerve in body
Descends along medial aspect of femur
Motor and sensory innervations to posterior thigh and majority of lower leg (except medial lower leg)

Sciatic Nerve (L4-S3)
In the popliteal fossa
Divides into:
Tibial Nerve (medial)
Common Peroneal Nerve (lateral)

Tibial Nerve
Travels down posterior calf
Passes under medial malleolus
Supplies skin of medial and plantar foot
Plantar flexion

PT= Posterior Tibial
Common Peroneal Nerve
Courses around head of fibula
Divides into:
Superficial Peroneal Nerve
Deep Peroneal Nerve
Peroneal nerves also called “fibular nerves”

Superficial Peroneal Nerve
Sensory nerve
Supplies anterior foot
Deep Peroneal Nerve
Motor innervation: dorsiflexion of foot
Sensory innervation: space between 1st & 2nd toe

Sural Nerve
Sensory nerve
Formed from tibial nerve
Passes under lateral malleolus
Supplies lateral foot

FEMORAL NERVE BLOCK
LOWER EXTREMITY BLOCKS
Approach is dependent on surgical site, risk of complications, and experience of anesthesia provider
Common lower extremity blocks:
FEMORAL AND ADDUCTOR CANAL BLOCK
FEMORAL NERVE BLOCK
Indications:
Knee
arthroscopy, postoperative analgesia for knee or hip arthroplasty (incomplete), operations of the anterior thigh, quadriceps tendon repair, patella fracture repair, analgesia for femoral fracture, combined with sciatic nerve blocks to provide anesthesia for procedures of lower leg and foot

Patient selection:
Appropriate for most patients, superficial and easy to perform
May be performed in anticoagulated patients??

Enters thigh deep to inguinal ligament and takes a fattened shape
LATERAL TO FEMORAL ARTERY

1= femoral artery
2=femoral nerve (note flattened shape as nerve passes under inguinal ligament)
3=femoral vein
4= ASIS
5=Inguinal ligament
6=sartorius muscle

At the inguinal ligament- femoral nerve lies lateral to femoral artery (VAN= medial to lateral)
Not in vascular sheath
Lies deep to fascial lata & iliac fascia
Distally gives rise to saphenous nerve
(which provides cutaneous innervation to medial calf)

Femoral nerve lies lateral to femoral artery (VAN= medial to lateral)

Not in vascular sheath

Lies deep to fascial lata & iliac fascia- 2 “pops”

Lies on surface of iliopsoas muscle

FEMORAL NERVE BLOCK: PHARMACOLOGIC CHOICE
Motor block= higher concentrations
Sensory block= lower concentrations
Inject 20-40 ml of LA
Volume often dependent on if other blocks are being performed as well….always calculate toxic doses!
FEMORAL NERVE BLOCK:
EQUIPMENT
Sterile towels/gauze packs
Sterile gloves
2- 20 ml syringes with LA
3 ml syringe with 25 G needle or TB syringe for LA
2 inch/22 G insulated stimulating needle
PNS
Marking pen
*Some facilities have standard block trays
US machine with high frequency linear transducer (5-15 or 4-14 MHZ)
Gel

FEMORAL NERVE BLOCK: ULTRASOUND TECHNIQUE
Gather equipment
Supine position, bed flat
Leg neutral
Expose groin, mark inguinal crease and level of femoral crease
Palpate for
femoral artery

Skin and transducer prep
Use linear, high frequency 8-14 MHz transducer and gel
Choose appropriate depth: 3-4 cm
+/- nerve stimulator
Transverse orientation of transducer at femoral crease
Goal: visualize femoral artery
Adjust focus and gain to obtain best image

Goal: place needle tip directly adjacent to lateral aspect of femoral nerve.
Below fascia iliaca.
LA injection should show the femoral nerve being lifted off the surface of the iliopsoas muscle.


Identify FA and FV
Color Doppler to identify artery
Identify iliopsoas muscle
FN is hyperechoic (remember- highly reflective and brighter than surrounding structures)
Slightly tilting transducer cranially or caudally may help brighten nerve
Often in triangular hyperechoic region, superficial to iliopsoas
Fascial lata (hyperechoic line) superficial to FN

ILIOPSOAS MUSCLE
Insert needle
in-plane
in lateral to medial fashion
Needle shaft visualized
May confirm with electrical stimulation
Negative heme aspiration before and during LA injection
1-2 ml of LA may be injected to ensure proper needle placement
Administer 10-20 (up to 40) ml of LA

FEMORAL NERVE BLOCK: COMPLICATIONS
RARE!
INFECTION
HEMATOMA
PARESTHESIA
INTRAVASCULAR INJECTION
NERVE INJURY
RISK OF FALLS
FAILURE
ADDUCTOR CANAL BLOCK
Indications:
Medial lower leg, ankle and foot procedures involving skin of saphenous nerve distribution
May be used in combination with popliteal sciatic
Knee procedures:
Low volume: knee arthrosocpy and anterior cruciate ligament reconstruction (ACL)
High volume: total and uni-compartmental knee replacement
Due to proximal spread up the adductor canal causing sensory block of front of the knee devoid of motor blockade
Distal thigh and femur
High volume
Patient selection:
See femoral nerve block

ADDUCTOR CANAL BLOCK: ULTRASOUND
The adductor canal:
Hunter’s canal or sub-sartorial canal
Located in medial, middle third of leg
Canal is roughly triangular in cross section and formed by fascial planes of three muscles:
Vastusmedialis
Sartorius (roof of canal)
Adductor longus and magnus
Canal contains:
Femoral artery
Femoral vein
Saphenous nerve
Nerve to vastus medialis

ADDUCTOR CANAL BLOCK: EQUIPMENT
22 G 100 or 50 mm short beveled regional block needle or Tuohy needle for catheter placement
Aseptic skin solution
Sterile gloves
+/- 1-2 ml of 1% lidocaine for skin infiltration
Local anesthetic
Ultrasound machine
Sterile ultrasound gel

Goal:
Inject local anesthetic on medial aspect of mid thigh under the
sartorius muscle
around branches of
femoral nerve (saphenous nerve)
before it has exited the adductor canal

Supine position
Flex operative leg at knee and externally rotate (“frog leg” position)
Aseptic preparation of leg
Set ultrasound depth to 4-5 cm
Place
high frequency linear ultrasound probe
and sterile ultrasound gel on medial aspect of mid thigh
Transverse to long axis of leg
Identify femoral artery
Identify femoral vein
Easily compressible and just below artery
Identify branches of femoral nerve (saphenous)
Bright hyperechoic structures around artery
Optimize image by adjusting depth, gain and frequency as needed

Place probe on anterior thigh at the mid-point between the inguinal crease and medial epicondyle
Identify
femur
(variable but generally 3-5 cm)
Scan medially until the trapezoid/boat shaped
sartorius muscle
is visualized
Femoral artery
just below muscle in adductor canal
Saphenous nerve
may be too small to visualize
Block should be carried out just proximal to the level that the femoral artery dives deep to enter popliteal fossa

MEDIAL
LATERAL
SARTORIUS
ARTERY
FEMUR
LEFT LEG
ADDUCTOR CANAL
SARTORIUS
LEFT LEG
MEDIAL
ADDUCTOR LONGUS
ADDUCTOR CANAL BLOCK: ALTERNATIVE TECHNIQUE
Insert needle using
in-plane
technique from lateral to medial
Out of plane acceptable if needle tip visualized during entire procedure
Inject local anesthetic around artery
Low volume: 5-10 ml of long acting local anesthetic (0.25-0.5% bupivacaine or 0.2-0.75% ropivacaine)
High volume: 20-30 ml of long acting local anesthetic

TROUBLESHOOTING:
Failed block:
Repeat if within safe dose of local anesthetic
Pain on injection/resistance:
Likely intra-neural. Withdraw and inject
Symptoms of local anesthetic toxicity:
Stop injecting. Follow appropriate LAST treatment guidelines
Aspiration of blood:
Adjust needle until clear aspiration. Resume injection with vigilance

ADDUCTOR CANAL BLOCK: COMPLICATIONS
BLOCK FAILURE
INTRAVASCULAR INJECTION & LA TOXICITY
ALLERGIC REACTION TO LA
NERVE DAMAGE
HEMATOMA
CURRENT LITERATURE
Femoral nerve block vs. adductor canal block:
ACB offers a primarily sensory block with proven analgesic effects
ACB is associated with less quadriceps weakness compared to FNB
ACB may allow earlier ambulation and lower risk of falls compared to FNB
ACB may decrease postoperative opioid consumption postoperatively compared to FNB

POPLITEAL SCIATIC BLOCK
Indications:
Anesthesia and analgesia for foot and ankle surgery
Ankle surgery (ORIF), foot surgery or debridement, Achilles tendon repair, Hallux valgus repair, combination with saphenous nerve block for more complete anesthesia

POPLITEAL SCIATIC BLOCK
Patient selection:
Appropriate for more patients
Classic technique requires prone position

Sciatic nerve blockade prior to division into tibial and peroneal branches
Below the knee the only portion NOT covered by the sciatic nerve is the medial portion of leg (saphenous coverage)

A common epineural sheath envelops the tibial and peroneal nerve as it leaves the pelvis (as sciatic nerve).
Two nerves diverge approximately 4-10 cm above the popliteal fossa crease.
Sciatic nerve (in popliteal fossa) is lateral and superior to popliteal artery.
Nerves in own epineural sheath (not neurovascular sheath)

PROXIMAL
LATERAL
POPLITEAL SCIATIC BLOCK: ULTRASOUND TECHNIQUE
POPLITEAL SCIATIC BLOCK:EQUIPMENT
Sterile towels/gauze packs
Sterile gloves
2- 20 ml syringes with LA
3 ml syringe with 25 G needle or TB syringe for LA
2 inch/22 G insulated stimulating needle
PNS
Marking pen
*Some facilities have standard block trays
US machine with high frequency linear transducer (5-15 or 4-14 MHZ)
Gel

Gather equipment
Prone position
Identify landmarks

Operative leg should be slightly bent.
Foot resting freely above bed.

Identify popliteal fossa (draw a triangle)
Draw a line at the semitendinosus/semimembranosus muscles (3)
Draw a line at the tendons of the biceps femoris (2)
Base of triangle is skin crease behind the knee (popliteal fossa crease) (1)

From midpoint of base of triangle, measure 7 cm up and 1 cm lateral, mark an X
(some providers start at midpoint of triangle)

Skin and transducer prep
Use linear, high frequency 8-12 MHz
Choose appropriate depth: 3-5 cm
Transverse plane gives best image of sciatic
Scan starting from landmarks...OR...
Popliteal crease!!

Technique to locate nerves:
Locate popliteal artery in fossa (3-4 cm). Doppler may aid in identification
Superficial and lateral to PA is TN (hyperechoic, oval or round, with honeycomb pattern)
Follow nerve proximally to identify the CPN joining TN (generally 4-10 cm proximal to fossa)
CPN is generally more superficial and lateral to TN
Artery dives deep as transducer is moved proximally
Sciatic generally between 2-4 cm

Insert needle at lateral end of probe using in-plane technique
May confirm with electrical stimulation
Negative heme aspiration before and during LA injection
Inject 20-40ml of LA


POPLITEAL SCIATIC BLOCK: COMPLICATIONS
Infection
Use aseptic technique

Local anesthetic toxicity
Aspirate before and during injection

Hematoma
Stop if complaint of pain

Vascular injection
Avoid medial needle orientation toward vasculature

Nerve injury
Abort if complaint of pain

ASRA Practice Advisory on Local Anesthetic Systemic Toxicity
Joseph M. Neal, MD,* Christopher M. Bernards, MD,* John F. Butterworth, IV, MD,Þ
Guido Di Gregorio, MD,þ Kenneth Drasner, MD,§ Michael R. Hejtmanek, MD,* Michael F. Mulroy, MD,*
Richard W. Rosenquist, MD,|| and Guy L. Weinberg, MDþ
SUBARACHNOID
RAPID, BILATERAL ANESTHESIA FROM CERVICAL LEVEL TO LOWER EXTREMITY
IMMEDIATE UNCONSCIOUSNESS OR APNEA
HYPOTENSION AND/OR BRADYCARDIA
RAPID TREATMENT:
AIRWAY SUPPORT
EPHEDRINE OR ATROPINE
EPINEPHRINE
EPIDURAL
DELAYED PRESENTATION (5-10 MINUTES)
SEGMENTAL OR UNILATERAL
HYPOTENSION AND BRADYCARDIA
RAPID TREATMENT:
AIRWAY SUPPORT
EPHEDRINE OR ATROPINE
EPINEPHRINE
BP BLOCK: SEIZURE GENERALLY FIRST SIGN
INTRAVASCULAR INJECTION LIKELY DUE TO VERTEBRAL, CAROTID OR SUBCLAVIAN INJECTION CIRCULATING LA DIRECTLY TO BRAIN
INTRAARTERIAL INJECTION CHARACTERIZED BY SEIZURE RESOLVE QUICKLY WHEN INJECTION STOPPED
Roots (5)
Trunks (3)
Divisions (6)
Cords (3)
Terminal Branches (5 Major)

ANTERIOR
US wave represented by sine wave
Focusing:
Adjust focus (focal zone) at or 0.5 cm below level of target

Transducers used for PNBs typically range from 2-15MHz
<4 cm deep
>4 cm deep
Innervates pectoral girdle and upper limb
With CNS depressant drugs depression may be first observed sign
Cardiovascular effects:
Local anesthetics are
myocardium depressants
(except cocaine)
Negative inotropic action dose dependent and causes decreased myocardial contractility and CO
Arrhythmias
can manifest as conduction delays (prolonged PRI, complete heart block, sinus arrest, asystole) to ventricular dysrhythmias
Dysrhythmias due to LA overdose may be recalcitrant to traditional therapies

Cardiovascular sequence of events:
Low blood levels of LA:
Small increase in CO, BP and HR likely due to a boost in sympathetic activity and direct vasoconstriction
High blood levels of LA:
Hypotension from reduced peripheral vascular resistance, reduced cardiac output and malignant arrhythmias
Cardiac arrest

ABSOLUTE CONTRAINDICATIONS
Patient refusal
Active infection at site
True allergy to LA

Premedication:
Narcotic and benzodiazepine
Relieves anxiety
Prevents discomfort
Superficial blocks associated with minimal discomfort
Intraoperative management:
Sedation or light general anesthetic
Postoperative expectation:
Duration of sensory and motor block
Catheter placement
IV PCA (multimodal)
CONSIDER PATIENT'S BODY HABITUS
THANK YOU!
ALLERGY TO LA
True allergy to
amino-esters: RARE
Due to PABA (p-aminobenzoic acid)
True allergy to
amino-amides: MORE RARE
Anaphylaxis:
Hypotension, tachycardia, dsyrhythmias, bronchospasm, laryngeal edema, laryngeal edema
Stop!, 100% FiO2, IV fluids, Epi, benadryl, aminophylline, hydrocortisone
LOCAL ANESTHETICS
May be used as a guide. Does not apply to all clinical situations.
Tetracaine
1.5 mg/kg
2.5 mg/kg with epi
Cocaine
3mg/kg
Chloroprocaine
12 mg/kg
15 mg/kg with epi
Procaine
7 mg/kg
8 mg/kg with epi

MAX DOSES
Bupivicaine
2.5 mg/kg
3 mg/kg with epi
Ropivacaine
2.5 mg/kg
2.5 mg/kg with epi
Lidocaine
4.5 mg/kg
7 mg/kg with epi
Mepivacaine
4.5 mg/kg
7 mg/kg with epi
Etidocaine
4 mg/kg
5 mg/kg with epi
Prilocaine
6mg/kg
9 mg/kg with epi

Esters
Amides
1 mg/kg = Tetracaine
3 mg/kg = Bupivacaine
Ropivacaine
6 mg/kg =Lidocaine
Mepivacaine
12 mg/kg=Chloroprocaine
Skin and transducer prep
Use
linear, high frequency 8-14MHz transducer
Chose appropriate depth: 3 cm
Transverse orientation of transducer superior and parallel to clavicle
Roots- 5
C5-T1
Emerge through
interscalene groove

Trunks- 3
Superior, Middle, Inferior
Pass under clavicle over 1st rib
Form neurovascular bundle with
subclavian artery
Divisions- 6
3 Anterior and 3 Posterior
Cords- 3
Lateral, Medial, Posterior
Named in relation to axillary artery
Terminal branches- 5
Musculocutaneous, Median, Ulnar, Axillary, Radial
Intercostobrachial
Upper posterior-medial side of arm
NOT part of BP
Hyperechoic:
Image displayed BRIGHT or WHITE on screen
Bone, fascial sheaths, nerves below the clavicle, needle, blood vessel walls
Hypoechoic:
Image displaced DARK or “GRAYISH-BLACK” on screen
Nerves in interscalene and supraclavicular area
Anechoic:
Image with no reflection and BLACK on screen
Artery and vein lumens

INTERSCALENE BLOCK
Indications:
Shoulder and upper arm surgery
Landmarks:
Interscalene groove at C6 or 3-4 cm above clavicle
Depth: 2-3 cm
Transducer: high frequency linear
Goal: Identify nerve roots between anterior and middle scalene muscles and watch LA spread
NERVES HYPOECHOIC
Side effects/complications:
Phrenic paresis, Horner's syndrome, intraarterial, epidural/subarachnoid injection, RLN block, pneumothorax, infection, bleeding, nerve injury
SUPRACLAVICULAR BLOCK
Indications:
Arm, elbow, forearm, hand surgery
Landmarks:
Subclavian artery, clavicle, Interscalene groove
Depth: 3 cm
Transducer: high frequency linear
Goal: Visualization of BP near subclavian artery just superior to clavicle and injection of LA around the trunks/divisions that are lateral and superficial to artery
Side effects/complications:
Pneumothorax, hemothorax, phrenic nerve paralysis and Horner’s syndrome

FEMORAL NERVE BLOCK
Indications:
Anterior thigh, femur, knee surgery
Landmarks:
Femoral artery at femoral crease
Depth: 3-4 cm
Transducer: high frequency linear
Goal: place needle tip directly adjacent to lateral aspect of femoral nerve
Side effects/complications:
Rare, intravascular injection, risk of falls, nerve injury, paresthesia, infection


TROUBLESHOOTING:
Unable to identify adductor canal:
Check depth
Move probe circumferencially around thigh
Identify artery with Doppler
"Alternative method"
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