Spinals part 2

Question 1

in what order are nerve fibers sensitive to LA? (most sensitive to least sensitive)

in what order are they blocked? (first to last)

Answer 1

large myelinated > smaller myelinated > smaller unmyelinated

B fibers
C and A-Delta fibers
larger A-gamma, A beta, and A-alpha fiberes

Question 2

what do B fibers do?

Answer 2

preganglionic sympathetic efferents

Question 3

what do C and A-delta fibers do?

Answer 3

pain, temp, touch afferents

post ganglionic sympathetics

Question 4

factors that affect differential blocks?

Answer 4

size/myelination of the fibers
nodes of ranvier
location depth
Na and K channels on each nerve

Question 5

in waht order are the nervous systems blocked?

Answer 5

sympathetic, sensory, motor

Question 6

sings of a sympathetic block? and how to sympathetic, sensory, and motor block levels compare?

Answer 6

BP changes may be the first sign, and is usually 2 segments higher than the sensory block, which is usually 2 levels higher than a motor block

Question 7

most accurate way to check for sensory block?

Answer 7

sharp or broken tongue depressor

Question 8

is loss of sensation to cold or sharp pain first?

Answer 8

sesation to cold is first and occurs at higher levels

Question 9

what fibers are blocked first in motor blockade?

Answer 9

A beta and A gamma, A alpha is a profound block

Question 10

2 most important factors that affect height of nerve block for SAB?

Answer 10

baricity and patient position

Question 11

how do you get a saddle block? what is it good for?

Answer 11

sitting position for SAB, leave sitting for 3-5min with a hyperbaric solution. Great for lower perineal procedures

Question 12

how does LA distribute in position is sitting to supine with hyperbaric solution?

Answer 12

it moves more cephalad to the dependent region of the lumbar curve

Question 13

spine high points in cervical and lumbar lordosis?

Answer 13

C3 and L3

Question 14

spine low points in thoracic and sacral kyphosis?

Answer 14

T6 and S2 low points

Question 15

other factors affecting height of spinal block?

Answer 15

age - older ligamentum flavum gets tougher and intrathecal space gets compressed, so higher spread of LA

height, more distance to travel and can increase dose

weight, decrease in intrathecal and epidural space if obese or pregnant

spinal fluid rate of circulation (coughing and straining)

Question 16

hypobaric LAs?

Answer 16

tetracaine 0.33% with water
lidocaine 0.5% with water

Question 17

isobaric LAs?

Answer 17

tetracaine 0.5% with 50% CSF
lidocaine 2% with water
bupivicane 0.5% with water

Question 18

hyperbaric LAs?

Answer 18

tetracaine 0.5% with 5% dextrose
lidocaine 5% with 7.5% dextrose
bupivicane 0.5% with 8% dextrose
bupivicaine 0.75% with 8% dextrose

Question 19

primary goal of neuraxial anesthesia?

Answer 19

block afferent fibers located in dorsal roots

motor and sympathetic fibers are close and they get blocked as they pass through ventral root

Question 20

why must you use preservative free LA in SAB?

Answer 20

parabns high allergy potential
sulfites neurotoxic
EDTA muscle pain and can cause tetany

Question 21

should you use multi dose or single dose vial for SAB?

Answer 21

single dose

Question 22

mech of action of LA?

Answer 22

limits sodium cahnnels and stops propogation of a nerve impulse

Question 23

which LA has strongest attachment to NA channels?

Answer 23

bupivicaine

Question 24

how do LAs find their way to the spinal cord?

Answer 24

through virchow-robin spaces

insertion site of tiny blood vessels where local can get around the side of them

Question 25

which meds can increase duration of SAB? what dose for each?

Answer 25

epi 0.1-0.2ml of epi 1:1000 "epi wash" Neo 0.5-2mg clonidine (LA effect)

Question 26

what is added to LA to increase onset?

Answer 26

NAHCO3

Question 27

where are opiod receptors?

Answer 27

substantia gelatinosa and spinal cord

Question 28

what meds are MU opioid receptors responsive to?

Answer 28

morphine, meperidine, sufentanil, fentanyl, alfentanil

Question 29

What are MU2 receptors also responsible for?

Answer 29

decreased HR, RR, and euphoria

Question 30

SE of opioids?

Answer 30

N/V, itching, urinary retention N/V is the number one complaint

Question 31

why is fentanyl widely used?

Answer 31

it adheres to lipoproteins in the spinal cord due to its high lipid solubility, less drug available to diffuse to respiratory centers

Question 32

fentanyl dosing in SAB? what can it be combined with?

Answer 32

10-25mcg onset 5-10min DOA 2-4hours can be combined with morphine (must be preservative free)

Question 33

morphine dosing in SAB

Answer 33

0.1-.5mg onset 60-90min DOA 6-8hrs

Question 34

what should you be cautions with when using morphine in SAB?

Answer 34

delayed resp depression

Question 35

adequate dermatome levels for the following procedures? upper abdmonial surgery intestinal, gyn, urologic TURP vaginal delivery, hip surgery thigh surgery and lower leg amputation foot and ankle surgery perineal and anal surgery

Answer 35

T4 T6 T10 T10 L1 L2 S2-S5 (saddle block)

Question 36

needle size for spinals?

Answer 36

22-27 gauge

Question 37

is quinke point needle cutting?

Answer 37

yes

Question 38

is whitacre needle cutting?

Answer 38

no, pencil point

Question 39

line accross iliac crests?

Answer 39

Tuffiers line

Question 40

spinal considerations in prone jacknife positions?

Answer 40

use hypobaric or isobaric must aspirate CSF, it will not drip rectal procedures

Question 41

what do you need to make sure happens with legs in the lateral position?

Answer 41

good flexion of the legs

Question 42

why is potential lumbar spine rotation importnat?

Answer 42

it may impede access to the spinal canal

Question 43

what LA is typically used for jack knife position?

Answer 43

tetracaine with water caudal anesthesia can also be used, this is part of epidural space with a space in the sacral hiatus

Question 44

what size spinal needles need an introducer?

Answer 44

25-27 gauge

Question 45

what size needle no longer needs an introducer?

Answer 45

22gauge

Question 46

which way should bevel face on introducer needle for paramedian approach? midline?

Answer 46

up (why???) to the side

Question 47

what structures are passed through for subarachnoid block in midline position? lateral or paramedian approach?

Answer 47

skin subq tissue supraspinous ligament interspinous ligament ligamentum flavum epidural space dura matter arachnoid matter lateral or paramedian approach does not pass through the supraspinous or interspinous ligaments

Question 48

how often should BP cuff be set when starting a spinal?

Answer 48

every 2 min

Question 49

when is paramedian approach done and how is it done?

Answer 49

for patients unable to flex and arch their back. also for paties who are belived to have calcified ligaments, or after a couple attempts at midline walk laterally 1-2cm from spinous process as well as 1cm down, angle 45 degrees cephalad and 15 degress to midline. first resistance should be ligamentum flavum

Question 50

describe taylor approach

Answer 50

indications: difficult anatomy, kyphoscoliosos, scoliosis it is a modified paramedian appraoch, but done at L5-S1 interspace

Question 51

pros of SAB?

Answer 51

fast acting dense block - motor and sensory small volume minimzes toxicity less time and smpler to perform less N/V, decreased stress response, decreased opioids affects reticular activating system so pt can be somnolent

Question 52

cons of SAB?

Answer 52

hypotension is significant cant prolong the block lack of control with the level of the block