Regional/Neuraxial Flashcards
Median nerve function
Palmar/ventral: most of palm, all of index, middle fingers, lateral 1/2 of ring finger
Dorsal: Just the tips of index, middle, and lateral 1/2 ring fingers.
SENSORY TEST: pinch index finger
MOTOR TEST: thumb opposition
INJURY: (rare) → reduced sensation over palmar surface of thumb, index, middle, lateral ring finger.
→ from: traumatic antecubital IV placement, carpal tunnel syndrome (only nerve that passes thru carpal tunnel)
Axillary nerve function
Sensory: lateral aspect of shoulder
Motor: arm ABduction (deltoid contraction)
Musculocutaneous nerve function
Sensory: pinch lateral aspect of forearm. Supplies most of thumb side of forearm beyond hand. (Think where you put an art line in)
Motor: elbow flexion (biceps contraction)
Radial nerve function
[Ventral/palmar: thumb]
[[Dorsal:
-thumb
-back of hand
bottom 1/2 of:
—-index, middle, medial part of ring finger
Median/central forearm, elbow, area around biceps]]
Sensory test: pinch the web space between thumb and index finger
Motor test: elbow extension (triceps contaction), wrist + finger extension
INJURY: wrist drop
→ BP cuff too tight, IV pole, UE tourniquet, sheets too tight with arm tucking.
Ulnar nerve function
Supplies: pinky and medial 1/2 ring finger on both sides of hand.
Sensory test: pinch pinky finger
Motor test: pinky finger abduction
Injury: impaired sensation pinky and ring fingers. Chronic = claw hand
most commonly injured peripheral nerve
Landmarks of interscalene block
Clavicular head of SCM
Clavicle
Cricoid cartilage
Complications of interscalene block
Phrenic paralysis
→ fine in healthy pts, can be problematic with resp disease
Horner’s syndrome
→ stellate ganglion blockade. indicates success PAM
Inadvertent epidural/spinal
→ If needle directed too medially
Seizure
→ if in vertebral artery, as little as 1mL could cause
C6 neuropathy
→ cramp felt
RLN injury, pneumo (R>L), Bezold Jarisch
Landmarks of supraclavicular block
Clavicle, subclavian artery
Biggest risk of supraclavicular
Pneumothorax
Tall, thin patients at high risk
Block good for all UE cases except shoulder
What is a good block for a patient with respiratory issues?
Infraclavicular. (Cord level)
-Nerves are distant from the neuraxial structures and phrenic nerve, so diaphragmatic paralysis is rare.
However, it’s the most painful, bc needle has to pass thru pec major and pec minor
Landmarks of intraclavicular block
Coracoid process, clavicle
Works for cases below elbow
Complications of infraclavicular block
Vascular puncture
Pneumo (lower risk than interscalene and Supra)
Painful
Unique aspects of infraclavicular block
- Because there is high variability in location of cords, nerve stim is used with ultrasound
- Also, the nerves appear hyperechoic (bright instead of dark) at this location because there is ↑ amt of connective tissue around the nerve fascicles as they move distal to the extremity.
- Most painful
Lumbar plexus
L1-L4 +/-T12 Iliohypogastric, Ilioinguinal, Genitofemoral, Lateral femoral cutaneous, Obdurator, Femoral
Lateral fem cutaneous, obdurator, and femoral are really the only three you need to understand
Sacral plexus
L4-S4
Posterior femoral cutaneous, sciatic
Covers all of foot
(Sciatic → Common peroneal → Superficial peroneal, deep peroneal
→ Tibial → Sural, posterior tibial)
Coccygeal plexus
S4-Co
Pudendal, inferior anal, perianal
Tibial nerve
-Branch of sciatic
→ SURAL: outer edge of foot
→ POSTERIOR TIBIAL: back of heel
Common peroneal nerve
-Branch of sciatic
→ SUPERFICIAL PERONEAL: top of foot, medial ankle
→ DEEP PERONEAL: between 1st two toes
→ COMMON PERONEAL: lateral upper calf
Femoral nerve
→ What’s the main branch?
Arises from lumbar plexus (L2-L4)
Sensory: Anterior thigh, front of knee, medial inner thigh.
Motor: sartorius, quads.
→ SAPHENOUS is main branch. Sensory to medial/inner lower leg.
Obdurator nerve
Arises from lumbar plexus.
Sensory: inner/medial knee
Motor: hip adductors
Lateral femoral cutaneous nerve
Posterior femoral cutaneous nerve
- LFC arises from lumbar plexus. Lateral thigh
- PFC arises from sacral plexus. Back of thigh, back of knee
Sciatic nerve: general and main branches
Arises from sacral plexus. Largest nerve in body. Motor to posterior thigh, motor and sensory to most of lower leg via common peroneal and tibial branches.
→ COMMON PERONEAL → superficial peroneal + deep peroneal
→ TIBIAL → sural + posterior tibial
What blocks could you do to foster tolerance of a lower leg tourniquet? What about an arm tourniquet?
Lower: sciatic and saphenous
Upper: have to cover in the intercostobrachial nerve (whatever..)
Risks of prolonged cross legged injury
Superficial peroneal and sural nerve injury
Function of each peripheral nerve type
A alpha: motor
A beta: pressure
A gamma: muscle tone
A delta: temperature
Psoas compartment block (lumbar block)
-Targets LFCn, femoral, obdurator
-Useful when neuraxial is C/I and anesthesia to one LE is preferred.
-Has one of the highest complication rates, esp hematoma, and renal capsular injection. Coagulopathy is a CI.
Creates sympathectomy of extremity.
How could you provide complete coverage of lower extremity?
Femoral + sciatic
Structures passed thru during insertion of femoral nerve block
2 pops felt
-fascia lata, fascia iliaca
Adductor canal block
Can be thought of as a femoral nerve block lower down in the thigh, more motor sparing. Good for knee surgery, affects quads less, allows earlier ambulation.
Fascia iliaca block
- no need for ultrasound or nerve stim
- can be used for hip fractures
- line drawn from pubic tubercule to ASIS = inguinal ligament
- line divided into thirds, needle insert 1cm caudal to where lateral third meets middle third
- covers lateral femoral cutaneous and femoral nerve
Tibial nerve
Inversion, plantar flexion
Peroneal nerve
Eversion, dorsiflexion
Needle insertion tibial ankle block
Between medial malleolus and Achilles’ tendon.
→ palpate tibial artery (behind medial malleolus) and insert needle perpendicular to skin, lateral to artery.
Sural nerve ankle block insertion point
Between lateral malleolus and Achilles’ tendon.
Deep peroneal ankle block needle insertion
Superior/top portion of ankle. Just medial to DP artery. Ask patient to flex foot against resistance, makes tendons of anterior tibial muscle and long muscles of big toe more visible.
Saphenous nerve ankle block needle insertion
Anterior aspect of medial malleolus (in front of it). Follows right along saphenous vein. Nerve is superficial to the vein.
How many vertebrae of each kind are there?
- C7
- T12
- L5
- S5
- C4
Borders of epidural space
Cranial border: foramen magnum
Caudal border: Sacrococcygeal ligament
Anterior border: Posterior longitudinal ligament
Lateral border: Vertebral pedicles
Posterior borders: Ligamentum flavum, vertebral lamina
How many spinal nerves are there?
31 paired
Key dermatomes to know
C6 - thumb C7 - pointer, middle C8 - ring, pinky T4 - nipple T6 - xiphoid T10 - umbilicus T12 - pubic symphisis
Primary site of action of spinal anesthesia
-Myelinated preganglionic fibers of spinal nerve roots.
Things that affect spread of spinal anesthesia
- Baricity
- Patient position
- Dose
- Site of injection
- Volume, density of CSF (not controllable)
Primary determinant of epidural anesthetic spread
Volume
Differential blockade spread with spinal anesthesia
Autonomic blockade 2-6 dermatomes higher than sensory
Sensory block 2 dermatomes higher than motor block
Differential spread of epidural anesthesia
No autonomic blockade with epidural.
-Sensory block is 2-4 levels higher than motor.
Order of onset of peripheral nerve blockade by nerve fiber type
B, C, A gamma+A delta, A alpha+beta
Classification of peripheral nerves
HEAVY:
A alpha: skeletal muscle, motor, proprioception. Fastest.
A beta: touch, pressure. Fast.
MEDIUM:
A gamma: skeletal muscle tone.
A delta: fast pain, temperature, touch.
B: preganglionic ANS. Lightly myelinated.
UNMYELINATED:
C (sympathetic): Postganglionic ANS
C (dorsal root): slow pain, temperature, touch.
MS and neuraxial
Epidural probably ok. However, spinal may exacerbate symptoms.
Specific gravity of CSF
1.002-1.009
Cutting tip needles
Quinke, Pitkin.
Require less force, but higher risk of PDPH.
Non cutting tip needles
Pencil point: Sprotte, Whitacre, Pencan
Rounded tip: Greene
Require more force, but less risk PDPH.
Caudal dosing peds
Sacral: 0.5mL/kg
Sacral to low thoracic: 1mL/kg
Sacral to mid thoracic: maybe 1.25mL/kg
Any concentration of bupivicaine, levobupivicaine, or ropivicaine may be used as long as dose does not exceed 2.5mg/kg.
For adult, 12-30mL total. Not doing these on most adults. Whatever.
Where does spinal cord end?
Ends in a taper as the conus medullaris.
Adult: L1-L2
Infant: L3
Where does the subarachnoid space terminate?
At the dural sac.
Adult: S2
Infant: S3
Triamcinolone epidural administration
- Commonly administered into epidural space to treat pain r/t lumbar disc disease (radiculopathy or nerve root compression)
- It’s unique because it’s associated w ↑ incidence of skeletal muscle weakness compared to other steroids, also more likely to cause sedation and anorexia
Landmarks for caudal block
Superior iliac spines and sacral hiatus
Needle is inserted at sacral hiatus
S/S epidural abscess
Localized back pain, radicular pain, sensory or motor deficits, ultimately paralysis
Can happen a few days after a catheter - hematoma s/s are quick and acute
Drugs that prolong block DOA
Drugs that provide supplemental analgesia
Epi
Dexamethasone
Dextran
supplemental analgesia: epi, neuraxial opioids, clonidine
