Regional Anesthesia: Upper and Lower Blocks Flashcards
Describe the Brachial Plexus
ROOTS: C5-T1(Ventral Rami)
TRUNKS:
- C5 and C6 converge to make the Superior Trunk
- C7 makes the Middle Trunk
- C8 and T1 converge to make the Inferior Trunk
DIVISIONS:
- Each trunk gives rise to make 1 anterior and 1 posterior trunk
- All three posterior divisions from the three trunks converge
CORDS:
- The anterior divisions from the superior and middle trunks converge together to make the lateral cord
- ALl three posterior trunks converge together to make the posterior cord
- The anterior division of the inferior trunk continues by itself to make the medial cord
- NOTE: The cords are named in relationship to the axillary artery – remember the brachial plexus is not 2D
BRANCHES:
- The lateral cord gives rise to the musculocutaneous nerve
- The posterior cord gives rise to the axillary and radial nerves
- The medial cord gives rise to the ulnar nerve
- the lateral and medial cords give rise to the median nerve
“ Most Athletes Must Really Unite”
What is the difference between a normal plexus, a prefix plexus and a postfixed plexus?
Prefixed plexus: C4 may contribute to the brachial plexus
Normal Plexus: C-T1 contributes to the brachial plexus
Postfixed plexus: T2 may contribute to the brachial plexus
Where do each areas of the brachial plexus branch from?
Roots: pass between the anterior and middle scalene muscles
Trunks: Roots converge to make the trunks at the lateral border of the scalene muscles
Divisions: each trunk diverges into an anterior and posterior division underneath the clavicle and over the 1st rib
- Note: the anterior divisions innervate the anterior (flexor portion of the arm) and the posterior division innervate the posterior (extensor) parts of the arm
Cords: divisions converge into cords when the brachial plexus goes under the pectoralis minor muscle
Branches: Cords diverge into branches in the axilla
What are some of the other nerves that are affected when performing a supraclavicular block that are not terminal branches of the brachial plexus?
DOrsal Scapular Nerve (C5)
- Innervates the elevator scapular and rhomboid muscles
Suprascapular nerve (C5-C6)
- innervates the supraspinatus m , infraspinatus m, posterior glenohumeral joint, subacromial bursa and acromioclavicular joint
Long thoracic nerve (C5-7)
- innervates the serratus anterior m
What are some of the other non-terminal branches of the brachial plexus that are affected when performing an infraclavicular block?
Lateral pectoral n (C5-7)
- innervates the pectorals major muscle and the acromioclavicular joint
Medial Pectoral nerve (C8-T1)
- Innervates the pectorals minor and the lower region of the pectoral’s major muscle
Describe the phrenic nerve in relation to regional anesthesia
Answer: Phrenic nerve originates from the anterior rami of C3-C5.
It is not a component of the brachial plexus but it does receive a contribution from C5
The phrenic nerve innervates the diaphragm, which explains why some approaches to the brachial plexus cause hemidiaphragmatic paralysis
Hemidiaphragmatic paralysis can lead to respiratory compromise in patients with poor pulmonary reserve (ie: COPD)
Describe the supraclavicular nerve and its relation to regional anesthesia
Answer: Component of C3-4, and is not a specific component of the brachial plexus. It arises from the cervical plexus
It provides sensory innervation to the “cape of the shoulder”, which encompasses the midline to the deltoid along with the second rib anteriorly to the superior aspect of the scapula posteriorly. It also innervates the clavicle
This region is BEST ANESTHETIZED with a superficial cervical plexus block
Describe the intercostobrachial n. and its relation to regional anesthesia.
Answer: The intercostobrachial nerve is not a component of the brachial plexus as it arises from the second intercostal nerve.
It is a branch of T2.
It provides sensory innervation to the medial aspect of the upper arm
A field block may be required to block this nerve for UE procedures. Can also foster tolerance of an upper arm tourniquet in an awake patient
With the arm abducted and externally rotated, begin at the deltoid prominence and move inferiorly towards the triceps. A total of 5mL of LA is sufficient
Describe the skin innervation dermatomes from the brachial plexus.
C4 = superior aspect of the shoulder
C6= Lateral shoulder
C7= 3rd digit
C8 = 5th digit
T1 = medial aspect of the arm
T2 = Axilla
What does the axillary nerve innervate (sensory and motor)?
Answer: gives sensation to the lateral upper arm at the shoulder and gives rise to shoulder aBDuction (deltoid contraction)
What do the intercostobrachial and the medial brachial cutaneous nerves innervate (sensory and motor)?
Answer: the Medial upper arm to the elbow, no motor function
What does the median antebrachial cutaneous nerve innervate?
Answer: gives sensation to the anterior upper arm, and the anterior and medial forearm to the wrist. There is no motor function here.
What does the musculocutaneous nerve innervate (sensation and motor)?
The musculocutaneous nerve gives rise to the lateral antebrachial cutaneous nerve that gives sensation to the lateral aspect of the wrist.
This musculocutaneous nerve allows for the following motor movements:
- Elbow flexion (biceps contraction)
- Forearm supination (palm faces upward)
The lateral antebrachial cutaneous nerve does not have any motor function as it is an extension of the musculocutaneous nerve below the elbow
What does the radial nerve innervate (sensory and motor)?
Sensory: Lateral upper arm, posterior arm below shoulder, posterior forearm, dorsal of the hand lateral to the axial line of the 4th digit, and the radial side of the thumb
Motor: Elbow extension (Tricep contraction), wrist extension, finger extension, thumb abduction
What does the median nerve innervate (sensory and motor)?
Sensory: Palmar side of the 1st, 2nd and 3rd digits and the tips of the dorsal side, radial side of the of the 4th digit
Motor: Forearm pronation (palm faces downwards, finger flexion (first 3.5 digits)
Thumb opposition (brings thumb to contact a finger)
Describe the interscalene block, including indications, target, technique and acceptable responses to the block.
Block targets the C5-7 roots of the brachial plexus
Indications:
Surgical procedures of the shoulder, upper arm and clavicle
NOTE: Clavicular surgery may also require a superficial cervical plexus block
NOTE: The inferior trunk is spared approximately 30% of the time –> not ideal for procedures below the elbow
US Technique:
1. Position patient supine either head slightly elevated, facing the non-operative side
2. Cleans, prep, and drape
3. Use high-frequency linear array transducer
4. Find clavicle, then scan up to find the “bunch of grapes” lateral to the pulsating subclavian artery and superior to the hyper echoic first rib.
5. Scan up to identify snowman or stoplight area
- Roots of the plexus will be between the anterior and middle scalene muscles
6. Place skin wheel and advance needle in a slightly caudal direction passing through the middle scalene muscle into the interscalene groove.
- guide needle in-between nerve roots to reduce risk of injury
7. following negative aspiration, inject increments of 5mL of LA so it achieves circumferential spread under direct visualization
- inject 7-15 mL of LA
Landmark technique:
1. LANDMARKS:
- Cricoid cartilage
- Clavicle
- Lateral border of the clavicular head of the sternocleidomastoid
2. Position pt supine with head slightly elevated and to the non-op side
3. Identify 6th cervical vertebrae by drawing an imaginary line laterally from the cricoid cartilage towards the clavicular head of the sternocleidomastoid muscle
- often, you can feel the transverse process of C6
3. Ask pt to slightly raise head to accentuate the clavicular head of the sternocleidomastoid muscle. Place your middle and index fingers on the lateral border of this muscle
- When the patient relaxes per your request, your palpating fingers will rest on the belly of the anterior scalene muscle.
4. Move your fingers to the lateral edge of the muscle to identify the groove between the anterior and middle scalene muscles
- Now your fingers straddle the crinoid line in the groove, you have your needle point of insertion
5. Skin wheel, then pass needle through wheel in a slightly caudal and posterior direction.
- this caudal tilt reduces the risk of entering the neural foramen or injecting into a dural nerve sheath
6. Advance needle approximately 1-2 cm until you elicit an acceptable motor response.
7. Reduce the nerve stimulator from 1mA to 0.5 mA to ensure sufficient needle proximity to target nerve
8. Following negative aspiration, inject increments of 5ML of LA while confirming negative aspirations between each injection. Inject 25-30 mL
Acceptable responses:
- Deltoid (shoulder abduction)
Pectoral’s major (arm internal rotation)
Biceps (elbow flexion)
Triceps (elbow extension)
Any twitch of hand or forearm
Not acceptable responses:
- Trapezius (Cervical plexus stimulation)
- Diaphragmatic (phrenic n. Stimulation –> Hiccups)
Describe the supraclavicular block, including indications, target, technique and acceptable responses to the block.
Targets the trunks and divisions of the brachial plexus
Indications: surgical procedures of the upper arm, elbow, wrist and hand
- NOT indicated for shoulder surgery because suprascapular nerve could be missed
US Technique:
** Most popular due to location of subclavian artery and pleura**
1. position pt in semi-sitting position with head turned to non-operative side
2. Cleanse, prep and drape
- Use high frequency linear array transducer in the supraclavicular fossa
3. Trunks and divisions of the brachial plexus appear as a series of hypoechoic circles (referred to as “bunch of grapes) lateral to the pulsating subclavian artery and superior to the hyperechoic first rib
4. Make a skin wheel
5. Pass 22G, 5cm needle through wheel in plane (lateral to medial) towards the inferior portion of the plexus where the first rib meets the subclavian artery (“corner pocket”)
6. Following negative aspiration, inject increments of 5mL of LA so it separates the plexus from the first rib.
- to achieve circumferential spread, you may need to redirect the needle to the superior aspect of the plexus
TOTAL VOLUME: 20-25 mL of LA
Pearls:
- Apply color doppler to identify aberrant vessels that course through needle path
- Ensure no portions of the plexus course superior or medial to the SCA. Failure to appreciate this will result in an incomplete block
- once all anatomic structures are identified, tilt transducer slightly caudal so first rib is aligned beneath the nerves (but over the pleura)
– MAKES a protective barrier against pneumothorax
Landmark Technique:
- Landmarks: Clavicle and clavicular attachment of the SCM 1. position pt in semi-sitting position with head turned to non-operative side
2. Cleanse, prep and drape
3. identify landmarks:
- Pt’s midline
- Clavicle
- Clavicular attachment of the SCM
4. Ask pt to relax the shoulder and flex the elbow
- allows you top rest the Forearm on the abdomen which will help you identify forearm and hand movements during nerve stimulation
5. Draw outline of SCM and clavicle to aid in identification during block
- lateral edge of SCM is drawn to insertion point on the clavicle
- positioning needle medial to this line increases risk of Pneumothorax
6. place finger approximately 2.5 cm lateral to SCM insertion point, directly above the clavicle
- injection site is just directly above your finger
- MAKE SKIN WHEEL
7. Attach 22G, 5cm needle to nerve stimulator and pass needle perpendicularly through wheel in a caudal direction parallel to the midline
- advance needle until you elicit a response
8. reduce nerve stimulator current to 0.5mA to ensure sufficient needle proximity to the target nerve
9. Following negative aspiration, INJECT ONLY 1mL TEST DOSE OF LA.
- if needle is placed correctly, fade will occur in subsequent motor responses
- if no signs of last, inject 5mL increments of LA while confirming negative aspirations
TOAL VOLUME 25-30 mL
Describe the infraclavicular block, including indications, target, technique and acceptable responses to the block.
Infraclavicular block targets the cords of the brachial plexus
Indications:
surgical procedures of the upper arm, elbow, wrist and hand
- Good alternative to supraclavicular block in patients with respiratory insufficiency
- good alternative to axillary block in pts with limited UE mobility
US Technique:
1. Palpate coracoid process and pace high-frequency linear array transducer in SAGITTAL plane below the clavicle, and medial to the coracoid process
2. Place high-frequency transducer in parasagittal position, just distal to coracoid press
- depending on body habits, you can use the linear array or the low-frequency curved array transducer
3. Identify axillary artery in cross section and adjust field of depth.
- Attempt to locate the three small hyper echoic cords in their corresponding positions to the axillary artery (Might not always see, so the nerve stimulator is useful here)
** Unlike the interscalene and supraclav, nerves at infraclavicular level appear hyper echoic (bright) rather than hypo-echoic
4. Insert needle distal to clavicle at cephalic end of the transducer, direct it towards the posterior aspect of the axillary artery through Pec major and minor muscles
- if using a nerve stimulator, will most likely encounter the lateral cord first (flexion of elbow or fingers)
5. Advance needle below axillary artery with goal of eliciting a posterior cord response (extension of wrist or fingers)
- an acoustic enhancement artifact posterior to the axillary artery is often mistaken for the posterior cord
6. Following negative aspiration, inject 1-2 mL of LA to ensure proper location.
- 5ML injected cephalic (towards lateral cord)
- 5mL injected caudal (towards medial cord)
Total volume: 20-30 mL
Pearls:
- In large pts, abducting the arm displaces the clavicle allowing more room to insert the needle cephalic to the transducer
- “Heel up” maneuver (rocking the transducer towards the pt’s head while compressing tissue caudally) makes it easier to see needle angle during insertion
- due to high variability of the cord locations, use nerve stimulator + US
- IF YOU CANNOT IDENTIFY THE CORDS, a reliable block can be achieved in depositing LA in a U-shape fashion around the axillary artery
Three most common errors that increase risk of Pneumo:
1. Needle insertion is too medial
2. Directing the needle medially
3. Needle insertion depth exceeds 6cm
Landmark Technique:
NOTE: there are actually 4 different techniques but we will do the coracoid technique
Landmarks:
- Clavicle
- Coracoid process
- Position pt supine with head turned to non-op side. position operative extremity at side or resting on abdomen
- Palpate the lateral tip of the coracoid process
- Draw a line 2cm medial and 2cm caudal and mark the point - insert needle with nerve stimulator in perpendicular and posterior direction.
- cords are usually contacted between 4cm in women and 4.25 cm in men
- goal: to obtain a distal motor response (ideally finger flexion or extension) - after you obtain this response, reduce nerve stimulator to 0.5 mA to ensure sufficient needle proximity
- Following negative aspiration, inject 1mL test dose.
- if placed correctly, will see fade in subsequent motor responses - If no signs of LAST, inject 5ml increments up to 25-35 mL total
Describe the axillary block, including indications, target, technique and acceptable responses to the block.
Most distal approach to the brachial plexus – targets 4 of the 5 terminal branches:
- Median
- Radial
- Ulnar
-Musculocutaneous
* DOES NOT TARGET AXILLARY
Indications:
- surgical procedures of the forearm and hand
- Axillary blockade is desirable in pts with full stomach who want to avoid GA
DOES NOT COVER:
- Skin of the medial upper arm (intercostobrachial n)
- Skin over the deltoid
US Technique:
1. Pt supine and abduct arm 90 degrees. Flex forearm upwards and parallel to the long axis of the body
2. Use high frequency array in axilla at crease formed by bicep and pectoralis major
3. Obtain image of axillary artery and terminal branches by placing transducer on the short-axis of the arm just distal to insertion of the pectorals major muscle
4. Perform a pre-procedure scan proximally and distally to accurately identify the nerve branches and determine the optimal location to perform the block
- When transducer is properly oriented,
- Median nerve lies superficial and lateral to axillary A.
- ulnar nerve lies superficial and medial to axillary artery
- Radial nerve lies posterior to axillary artery
- MC N lies lateral
5. Cleanse, prep and drape and insert needle until it is in close proximity of each nerve
- block radial first due to its deeper location
6. following negative aspiration, inject small amount of LA (3-5mL/nerve) under direct visualization
Total: 15-20 mL
LANDMARK TECHNIQUE
Landmarks:
- Axillary artery pulse
- Coracobrachialis m
- Pectoralis major muscle
- Bicep muscle
- Tricep muscle
- Position the pt supine and abduct arm 90 degrees upward. and parallel to long axis of body
- starting at lateral educe of pec major, palpate axillary artery
- then follow distally in the muscular groove between the coracobrachialis and triceps muscle
- mark artery as high in the axilla as practical - cleanse and prep
- palpate the proximal artery with index and third finger of non-dominant hand
- block intercostobrachial and median cutaneous nerves of the arm with SQ injection of 4-5 mL of LA
- will help pt tolerate block placement - Block median nerve:
- insert needle in slightly cephalad direction with NS.
- Advance needle above pulse until you stimulate the median nerve
- EXP: Forearm pronation and finger flexion
- confirm negative aspiration and inject 5-10 mL LA - Block Musculocutaneous nerve
- Bring needle back to skin but dont remove
- redirect needle into coracobrachialis m (also above axillary pulse)
- advance needle until you stimulate nerve (elbow flexion or bicep twitching)
- confirm negative aspiration and inject 5-10 mL LA - Block ulnar nerve
- Remove needle
-Advance it below the axillary pulse until you stimulate the ulnar nerve (thumb adduction + 4/5th digit flexion)
- confirm negative aspiration and inject 5-10 mL LA - Block radial nerve
- advance needle deeper until you encounter radial nerve (elbow/wrist extension and forearm supination)
- confirm negative aspiration and inject 5-10 mL LA
NOTE: if you puncture the axillary artery, it is okay to transition to transarterial technique
What must you understand about the terminal nerves relative to the axillary artery
With the pt in anatomic position, the nerves are located ____ in relation to the axillary artery (moving clockwise):
Median= Anterior and Medial
Ulnar = Posterior and medial
Radial = Posterior and lateral
Musculocutaneous = Anterior and lateral (resides outside of the neuromuscular bundle)
- exits proximal to the neuromuscular bundle and travels int he fascial plane between the bicep an the coracobrachialis m.
- location is variable and can be located INSIDE of the muscle as well
- must be blocked separately from the other three
Describe the lumbar
LUMBAR PLEXUS:
Arises from L1-4 and T12 contributes in 50% of the population
Forms within the Psoas major muscle in front of th transverse process of the lumbar vertebrae
Lies own the posts compartment between the posts major and quadrates lumborum muscles
Gives rise to 6 nerves but only really need to know the last three:
1. Illiohypogastric
2. Illioingunial
3. Gnetiofemoral
4. Lateral femoral cutaneous
5. Obturator
6. Femoral
Describe the lateral femoral cutaneous nerve.
Arises from L2-L3 (posterior divisions)
Forms at the midpoint of the posts muscle
Courses laterally along the anterior iliac spine then passes under the lateral border of the inguinal ligament
Describe the Femoral Nerve
Arises from L2-L4 (posterior divisions)
Forms near the middle and lower third of the psoas muscle
Courses distally though a groove created by the psoas major and illiacus muscle under the inguinal ligament lateral to the femoral artery and anterior to the iliopsoas muscle
Divides into anterior and posterior branches
- posterior branch gives rise to 1 terminal branch –> Saphenous nerve
- Saphenous nerve courses through the adductor canal and becomes superficial at the knee
Describe the Obturator Nerve.
Arises from L2-4
Forms near the medial border of the psoas muscle at the level of the sacroiliac joint
Courses through the obturator canal into the pelvis minor (often injured in pts undergoing extensive pelvic surgery )
Describe the sciatic nerve.
Arises from L4-S2 (comprised of the tibial and common fibular trunks)
Courses through the sacrosciatic foramen (underneath the piriformis muscle) and descends between the major trochanter and ischial tuberosity
Divides into 2 branches at the proximal popliteal fossa into:
Tibial N;
- Arises from sacral nerve (anterior branches of L4-S3)
- Courses medially through the popliteal fossa distally and between the medial and lateral heads of the gastrocnemius muscle.
- gives rise to 1 terminal branch: posterior tibial N.
Common peroneal (fibular) nerve:
- arises from sacral nerve (posterior branches of L4-S3)
- course laterally over the head of the fibula before dividing into the deep and superficial peroneal nerves
- gives rise to three terminal branches: deep peroneal nerve, superficial peroneal nerve and Sural Nerve
