Regional Anesthesia Flashcards
What layers does your needle travel through for epidural and spinal blocks?
Skin, subcutaneous tissue, supraspinous ligament, interspinous ligament, ligamentum flavum, epidural space (destination of epidural blocks), dura, subdural space, arachnoid, subarachnoid space (destination of spinal block).. Pia mater is the innermost layer, we do not go that far in blocks though
What space is occupied with CSF?
subarachnoid space
Dermatomes: what landmark is T4, T6, T8, and T10?
T4 nipple
T6 xiphoid
T8 last rib
T10 umbilicus
Dermatome: which nerve innervates the hand (multiple nerves, which part of the hand). If the pt starts feeling numbness/tingling of the hand during spinal/epidural, what interventions should be done?
pinky: C8
middle finger: C7
Index, thumb: C6
If the pt starts to feel numbness/tingling here, put pt in reverse trendelenberg
When doing a spinal, you hope to block which nerves?
Not above T1, when the block starts to spread to fingers, it can continue to spread to phrenic nerve (C3-C5) then the patient may loose ability to breathe on their own (“total spinal”)
CSF: How much of it is in the subarachnoid space? What is its specific gravity?
150 mL
1.004-1.008
It is expected that sensory, motor, and autonomic functioning will be blocked during spinal/epidural. What is the consequence of blocking autonomic functions in a spinal vs. epidural (on the heart)?
Epidural: BP will drop within 8 min
Spinal: BP will drop within 1 min, more profound
Along with BP dropping, C.O. drops 10% (give bolus before procedure), HR drops and SVR drops
Contraindications to regional blocks
Pt refusal, infection/cyst at injection site, increased ICP (for spinal), clotting defects/anticoags, hemorrhaging/hypovolemia, CNS disease/meningitis (for spinal), inability to remain still, bacteremia/septicemia, nerve damage/palsy (for peripheral)
Side effects of neuroaxial drugs (due to autonomic block)
MAP, HR, C.O., SVR decrease
hyperparistalsis, urinary retention, N/V
If high block, respiratory effects (phrenic nerve)
Blocks stress response, shivering
Sprotte vs. Quincke vs. Whitacre spinal needles, what size needle?
25g needle
Sprotte/ Whitacre are pencil point, more tip strength, feel “pop” when entering the dura
Quincke is cutting, make sure bevel to the side, less likely to feel “pop”, increased risk of postdural headache
Landmarks for spinal/epidural block
ileac crest and L4 vertebrae is palpated
Spinal block procedure order: Midline approach
- identify landmarks, 2. sterile field, prep solution, 3. fenestrated drape, wipe iodine away with sterile gauze, 4. skin wheal with 25g needle, 5. advance 17g introducer angled cephalad, stop in interspinous ligament, advance selected needle through ligamentum flavum, feel “pop”, 6. through dura to subarachnoid space, 7. aspirate CSF (confirm by rotating 90 degrees x4) 8. inject drug, pull out needle
What is an epidural headache, why does it occur? Treatment?
If dura is punctured, CSF can leak for a day, give pt extra fluids, bedrest
Epidural Blood Patch can be done, give pt 10-20 mL of their blood (IV) back into CSF
What is the Touhy needle used for?
Epidural placement, catheterized needle with markings every sonometer
What is the LOR technique
LOR: loss of resistance technique for correct epidural placement, when needle hits ligamentum flavum, stylet is removed and syringe with air is tapped and slowly advanced until a sudden loss of resistance
After getting the epidural in the correct location, how is the catheter placed?
Advance catheter 2-3 cm into epidural space
Advance catheter 4-6 cm into the epidural space in parturients (pregnant women)
Baracity of local anesthetic drugs with CSF: Hyperbaric, hypobaric, isobaric
Hyperbaric solution: has higher specific gravity, like dextrose, solution will “sink” and block lower
Hypobaric solution: has lower specific gravity, like sterile water, solution will “rise” and block higher
Isobaric solution: specific gravity 1.004-1.008, mix with CSF
Indications for caudal blocks
pediatric patients post op pain, landmark is sacral hiatus
Epidural Hematoma is a rare complication, what must be done if this occurs and what are signs/symptoms?
Weak/numbness in lower extremeties, neurosurgery consult immediately, usually caused by coagulation defect (LMWH must be held 12 hours before and 12 hours after surgery)
Risks of peripheral nerve blocks
LA (local anesthetic) toxicity, permanent nerve damage (from toxicity, usually nerve will repair), allergic response, incomplete blocks (convert to general), discomfort of positioning
2 classes of local anesthetics
esters: (one eyed ester, has one “i”) metabolized by cholinesterase, more likely to have allergic reaction
amides: metabolized by hepatic processes
Rate of absorption from max to min for nerve blocks
Intercostals, caudal, epidural, brachial plexus, sciatic, lumbar plexus, femoral
Signs of local anesthetic toxicity
- CNS toxicity: tongue numb, lightheaded, dizzy, tinnitus, disoriented, seizures, then CNS depression
- respiratory depression and arrest
- CV instability
Sciatic nerve block, which roots, where does this block
L4-S3, blocks posterior leg, foot, and below the knee
Landmarks for sciatic nerve block
Draw a line from posterior superior iliac spine to greater trochanter, then from greater trochanter to sacral hiatus, halfway through the second line is where the needle gets inserted
How much local is injected for each lower peripheral nerve block: femoral, popliteal, ankle, and sciatic
Femoral: 25mL, popliteal: 20-30mL, ankle: 5 sites x5mL=25mL, sciatic: 20-30
(about 25 for each)
Femoral nerve block landmarks, what does femoral nerve innervate
nerve is lateral to artery/vein, between psoas and iliacus, passes under inguinal ligament
innervates anterior thigh, knee, and hip joints, and small part of medial foot (via the saphenous branch)
Femoral nerve block: needle size and direction needle is inserted
needle 22g 50mm (5cm), B bevel (short angle) insulated needle, insert perpendicular to the skin, then advance 45 degree angle cephaldad, inject 25-35 mL
Peripheral nerve block complications
hematoma, IV injection- toxicity, nerve injury
Popliteal block landmarks, where is the needle inserted?
popliteal fossa crease, bicep femoris, semimembranosis, semitendonosis
needle inserted 7cm above the crease, midline (slightly lateral)
Ankle blocks: key point about drugs and stimulator
NEVER use epi, no nerve stimulator is necessary
Ankle blocks: what needle is used?
one source: 23-25g, 1 inch
other source: 22g, 38mm, B bevel
Ankle blocks: steps of blocking each nerve
- tibial- hit posterior tip of medial malleolus and post tib artery is in front of the nerve
- sural- behind lateral malleolus, between that and calcaneous
- deep peroneal- at ankle level, feel anterior tibial artery and extensor hallucis longus, needle lateral to artery or in groove of tendon
- “fan” the needle toward medial malleolus to block saphenous nerve
- fan the needle toward lateral malleolus to block superficial peroneal
What is an induced sympathectomy?
A benefit of regional anesthesia, causes intraop less blood loss and postop improved perfusion
VASODILATE, BETTER PERFUSION
Regional anesthesia set up/preparation
MSMAID: Monitors, Suction, Means of PPV (ambu bag), Airway (intubation equipment), IV access, Drugs
3 ways to tell if you are near the nerve
Ultrasound, nerve stimulator, illicit paresthesia (hit the nerve, not ideal)
Brachial plexus blocks will block sensory to all of the arm except for what?
Posterior shoulder innervated by cervical plexus
What are the roots for Musculocutaneous, Axillary, Radial, Median, and Ulnar?
Musculocutaneous: C5-C7 Axillary: C5-C6 Radial: C5-T1 Median: C5-T1 Ulnar: C8-T1
Radial nerve vs. Median nerve motor function
Radial: Supinators and EXtenders
Median: Pronators and Flexors
Black vs. Red on nerve stimulator: placement and +/-?
Red is positive, placed proximal
Black is negative, placed distal
A bevel vs B bevel
B bevel is shorter with a larger angle
Indications for interscalene approach of brachial plexus block: where does it block?
Shoulder/upper arm surgery because it blocks upper brachial plexus roots and trunks plus lower cervical plexus
Pt position and landmarks for interscalene approach
Supine with head turned away
The brachial plexus lays between the anterior and middle scalene
Clavicular head of sternocleidomastoid, clavicle, C6 (find cricoid cartilage), EJ vein, use “sniffing” technique to help identify these landmarks
Absolute contraindications to interscalene approach?
Relative contraindications?
Absolute: contralateral recurrent laryngeal nerve palsy, phrenic palsy
Relative: Preexisting nerve injury, brachial plexus pathology, impaired pulmonary function
Steps of interscalene approach with nerve stimulator
- identify landmarks, 2. clean with antiseptic, 3. insert needle slightly caudad while aspirating, 4. turn on nerve stim at 1mA, 5. continue until you see twitches below 0.5mA, 6. aspirate and inject 5mL at a time, give a total of 20-30mL 7. evaluate block
Ways to evaluate brachial plexus blocks, after local has been given
Have the pt PUSH, PULL, CLOSE hand, and OPEN hand
This is for arm extension-radial nerve, arm flexion-musculocutaneous, median nerve (close or pinch index finger), and ulnar nerve (open or pinch pinky)
Complications to interscalene approach
IV injection, subarachnoid injection, pneumothorax, phrenic nerve block, RLN block, and Horner’s syndrome (ptosis-eye droop, myosis-dilated eyes, anihydrosis- lack of sweating)
Interscalene doesn’t block ulnar nerve
Cervical plexus block indications and where does it block?
Done for unilateral surgery of the neck, it blocks C6 level, usually done with deep cervical plexus block of C2-C4 for carotid endarterectomy
Block is done at the posterior border of SCM
Supraclavicular approach to brachial plexus block will block where? What are landmarks?
Blocks trunks and divisions of brachial plexus, blocks hand, forearm, upper arm
Lateral border of SCM, right above the clavicle, groove between scalene muscles, aim needle caudally
Contraindications to supraclavicular block?
Contralateral phrenic paralysis, recurrent nerve paralysis, contralateral pneumothorax
Supraclavicular block complications?
Pneumothorax, Horner’s syndrome, phrenic nerve block, recurrent laryngeal nerve paralysis, neuropathy
Infraclavicular approach: landmarks, where does it block
Medial clavicular head and coracoid process, needle inserted below clavicle, pointed laterally (as needle advances, pectoral twitches may happen first)
Blocks elbow, forearm, hand
Axillary block indications, positioning, and landmarks
indications: procedures below the elbow, this will block the terminal branches (musculocutaneous may need an extra stick)
positioning: supine, arm extended, forearm flexed 90 degrees
landmarks: axillary artery, median nerve is superior, ulnar nerve is inferior, radial nerve is posterior (transarterial technique with this block is possible, but not best due to risk of hematoma)
Absolute contraindications specific to axillary block
lymphangitis
What are the landmarks for “touchup” nerve blocks of the brachial plexus (except axillary)?
Musculocutaneous: coracobrachialis
Median: medial to brachial artery
Ulnar: ulnar groove between medial epicondyle and olecranon process
Radial: lateral to brachioradialis and biceps tendon
Bier block
40 mL IV give local anesthetic with double tourniquette/cuff, lasts up to 2 hours, patient discomfort is possible
What effects the spread of spinal injection
baracity, position, concentration, level of injection
How do you position a patient for femoral nerve block? For popliteal nerve block?
Femoral: supine, slight external rotation of the femur
Popliteal: prone with operative leg slightly flexed
Landmarks of interscalene block?
Posterior border of SCM at C6, then roll fingers posterior to groove between anterior and middle scalene
To accentuate the landmarks, have patient sniff
What are the advantages to regional anesthesia? (peripheral)
Induced sympathectomy (intraop reduction in blood loss, postop improvement in perfusion - vasodilates), reduced N/V, preemptive analgesia, and can avoid general anesthesia
What part of the brachial plexus do these techniques block… interscalene, supraclavicular, infraclavicular, axillary?
Interscalene: roots and trunks
Supraclavicular: trunks and divisions
Infraclavicular: cords
Axillary: branches
What are 3 reasons to have an emergency set up with you during a regional technique?
- LA toxicity
- allergic reaction
- conversion to general
