Neuraxial blocks 3

Question 1

_____ is the primary determinant of epidural block height

Answer 1

Volume

Question 2

The initial dosing for epidural is

Answer 2

1-2 mL per segment to be blocked

Question 3

The “top-up” dose for epidurals is

Answer 3

50-75% of the initial dose

Question 4

A “top-up” dose should be administered

Answer 4

before the block recedes more than 2 dermatomes

Question 5

The volume of the epidural space is smaller in the thoracic region when compared to the lumbar region. Therefore, for a given volume of local anesthetic, you’ll achieve ______ spread in the thoracic region as compared to the lumbar region.

Answer 5

Greater

Question 6

________ is the primary determinant of epidural block density

Answer 6

Concentration

Question 7

The following drugs can be used for epidural dosing

Answer 7

2-chloroprocaine 3%
lidocaine 2%
ropivacaine 0.1-0.75%
bupivacaine 0.0625-0.5%
levobupivacaine 0.0625-0.5%

Question 8

Describe the onset of action for chloroprocaine, lidocaine, ropivacaine, bupivacaine, and levobupivacaine for epidural use.

Answer 8

2-chloroprocaine- 5-15 minutes
lidocaine- 10-20 minutes
ropivacaine, bupivacaine, and levobupivacaine 15- 20 minutes

Question 9

Identify the MOST appropriate techniques for subarachnoid block in a patient scheduled for hemorrhoidectomy.
a. lidocaine 5% in 7.5% dextrose and the sitting position
b. bupivacaine 0.3% in water and the jackknife position
c. Tetracaine 0.2% in water and the sitting position
d. procaine 10% in water and the jackknife position

Answer 9

a & b.

Question 10

______ describes the density of a local anesthetic solution relative to the CSF

Answer 10

Baricity

Question 11

When injected inside the subarachnoid space, a hyperbaric solution will

Answer 11

sink

Question 12

When injected inside the subarachnoid space, a hypobaric solution will

Answer 12

rise

Question 13

When injected inside the subarachnoid space an isobaric solution

Answer 13

will remain in place

Question 14

As a general rule, solutions in dextrose are______

Answer 14

hyperbaric

Question 15

As a general rule, solutions in saline are _____

Answer 15

isobaric

Question 16

As a general rule solutions in water are______

Answer 16

hypobaric

Question 17

_________ is an exception to the general rules of baricity because it contains many molecules making it hyperbaric

Answer 17

Procaine 10% in water

Question 18

If we are using a hyperbaric solution and we keep the patient in the sitting position after the block,

Answer 18

a hyperbaric solution will sink and anesthetize the sacral nerve roots causing a saddle block

Question 19

If we lay a patient supine after a block with a hyperbaric solution, the solution will

Answer 19

slide down the lumbar lordosis and eventually pool in the sacrum and the thoracic kyphosis (pools low)

Question 20

If we keep the patient in the sitting position after a hypobaric block, the solution will

Answer 20

rise towards the brain

Question 21

How does neuraxial anesthesia affect respiratory mechanics?
a. impaired inspiration
b. impaired expiration
c. no impairment
d. impaired inspiration and expiration

Answer 21

D. - accessory muscle function is reduced by neuraxial blockade

Question 22

Systemic effects of neuraxial anesthesia to the cardiovascular system include

Answer 22

hypotension
vasodilation
variable effect on HR & CO
bradycardia

Question 23

How can neuraxial anesthesia result in bradycardia?

Answer 23

inhibition of cardioaccelerator fibers at T1-T4
unloading of ventricular mechanoreceptors–> Bezold-Jarisch reflex
unloading of the stretch receptors in the SA node

Question 24

What are the respiratory effects of neuraxial anesthesia.

Answer 24

in healthy patients has negligible effects on minute ventilation, tidal volume, RR, dead space, and arterial blood gas tension
accessory muscle function is reduced including impairment of the intercostal and abdominal muscles resulting in decreased pulmonary reserve

Question 25

Describe the CNS effects of neuraxial anesthesia

Answer 25

drowsiness

Question 26

Describe the neuroendocrine effects of neuraxial anesthesia

Answer 26

diminished sympathetic response to surgical stress

Question 27

Describe the gastrointestinal effects of spinal anesthesia

Answer 27

relaxation of sphincters and increased peristalsis

Question 28

Describe the effects to the kidney and liver when performing neuraxial anesthesia.

Answer 28

as long as systemic blood pressure is maintained, hepatic and renal blood flow and function are unchanged

Question 29

What spinal levels give rise to the cardioaccelerator fibers?

Answer 29

T1-T4

Question 30

What reflex contributes to asystole that occurs with spinal anesthesia?

Answer 30

Bezold-Jarisch reflex- the heart slows to allow it adequate time to fill

Question 31

How does a spinal to T4 affect minute ventilation in healthy patients?

Answer 31

it has a negligible effect

Question 32

What is the most likely cause of apnea due to spinal anesthesia

Answer 32

Brainstem hypoperfusion (not phrenic nerve paralysis or high concentrations of LA in the CSF

Question 33

When compared to intrathecal fentanyl, which findings are MORE likely with intrathecal morphine? a. wider band of analgesia b. increased risk of nausea c. late respiratory depression d. higher plasma concentration e. faster onset f. sympathectomy

Answer 33

A, B, C

Question 34

An opioid deposited into the intrathecal space can easily

Answer 34

diffuse into the spinal cord

Question 35

An opioid deposited into the epidural space must first diffuse across _________ before entering the CSF. Some of the drug also diffuses into the __________.

Answer 35

dural cuff; bloodstream

Question 36

Neuraxial opioids inhibit

Answer 36

afferent pain transmission in the substantia gelatinosa (lamina 2 of the dorsal horn)

Question 37

Neuraxial opioids do NOT cause:

Answer 37

sympathectomy, skeletal muscle weakness, changes in proprioception

Question 38

______ is the most lipophilic opioid, and _____ is the most hydrophilic opioid.

Answer 38

Sufentanil; morphine

Question 39

Key characteristics of lipophilic opioids include

Answer 39

a shorter duration of action, less spread in the CSF, and risk of early respiratory depression

Question 40

Key characteristics of hydrophilic opioids include

Answer 40

longer duration of action, greater spread in the CSF, and risk of early and late respiratory depression

Question 41

When combined with local anesthetics, ______ create a denser block

Answer 41

neuraxial opioids

Question 42

Identify the MOST common side effect of neuraxial opioid administration. A. pruritus B. respiratory depression C. urinary retention D. Nausea & vomiting

Answer 42

A. pruritus

Question 43

The four key side effects of neuraxial opioids include:

Answer 43

pruritus respiratory depression urinary retention Nausea & vomiting

Question 44

Respiratory depression is more common with_______- in neuraxial opioid administration.

Answer 44

high opioid doses co-administered sedatives low lipid solubility (hydrophilic) advanced age opioid naivety increased intrathoracic pressure

Question 45

__________ is most common in young males, and it's more common with neuraxial opioids when compared to IV and IM administration.

Answer 45

Urinary retention

Question 46

_________ reduces the efficacy of epidural opioids.

Answer 46

2-Chloroprocaine

Question 47

Epidural morphine may _________ in obstetric and postpartum patients.

Answer 47

reactivate herpes simplex labialis

Question 48

Any opioid that enters the systemic circulation becomes available to

Answer 48

cross the placenta and enter the fetus

Question 49

When treating pruritus related to intrathecal injection of opioids, what medications should be given?

Answer 49

can be treated with an opioid antagonist such as naloxone diphenhydramine doesn't fix the cause, but its sedative effects may be beneficial

Question 50

Nausea and vomiting is caused by activation of the opioid receptors in the

Answer 50

area postrema of the medulla and vestibular appartus

Question 51

Transfer of opioids from the epidural space to breast milk is

Answer 51

minimal

Question 52

What is the mechanism of neuraxial opioid-induced urinary retention?

Answer 52

inhibition of sacral parasympathetic tone. this causes bladder detrusor muscle relaxation and urinary sphincter contraction