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Mar: Sem 3 - Principles I (Grayson) > Exam 1- Neuraxial Principles (6/01/23) > Flashcards

Exam 1- Neuraxial Principles (6/01/23) Flashcards

1
Q

What adjunct agents are lipophilic in spinal blocks and rapidly spread to the spinal cord?

A
  • Fentanyl and Sufentanil
  • Early respiratory depression
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2
Q

Besides respiratory depression, an overdose of opioids can cause what adverse effects?

A
  • Muscle rigidity
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3
Q

Which opioids are the best adjunct agents for spinal anesthesia in an outpatient setting?

A
  • Fentanyl and sufentanil d/t to them being lipophilic agents and having a quick onset.
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4
Q

What does ERAS stand for?

A
  • Enhance Recovery After Surgery

ERAS attempts to minimize the use of opioids to improve patient outcomes.

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5
Q

What were the three main side effects of neuraxial opioids discussed in the lecture?

A
  • Pruritus
  • Respiratory Depression
  • PONV
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6
Q

What is the incidence of pruritis from neuraxial opioids?

A
  • 30-100%
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7
Q

What are the treatments for pruritus from neuraxial opioids?

A
  • Benadryl 25-50 mg IV
  • Naloxone 0.1 mg IV (best)
  • Buprenex (mixed agonist/antagonist)

Although Naloxone is the best treatment for pruritus, it will also reverse the analgesic properties of the opioid resulting in the patient being in pain.

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8
Q

What are prophylactic managements for pruritus from neuraxial opioids?

A
  • Minimize the dose of morphine to < 300 mcg
  • Ondansetron 4 mg IV
  • Nubain 2.5-5.0 mg IV
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9
Q

__________neuraxial opioids will have delayed respiratory depression and a cephalad spread.

A
  • Hydrophilic (Morphine)
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10
Q

__________neuraxial opioids will have early/ immediate respiratory depression.

A
  • Lipophilic (Fentanyl/Sufentanil)
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11
Q

Neuraxial opioids can be reversed with what medication?

A
  • Naloxone 0.1-0.2 mg
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12
Q

What does this graph show?

A
  • Respiratory depression peaks almost immediately when the patient receives fentanyl/ sufentanil
  • Repression depression peak is delayed when the patient receives morphine.
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13
Q

PONV from neuraxial opioids is very dose-dependent. What is the recommended neuraxial dose of morphine?

A
  • < 300 mcg
  • At less than 100 mcg N/V will almost be absent
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14
Q

What is the treatment for PONV from neuraxial opioids?

A
  • Ondansetron (5 HT antagonist) 4-8 mg
  • Naloxone 0.1 mg
  • Phenergan 12.5- 25 mg IM
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15
Q

What is the incidence rate of urinary retention from neuraxial opioids?

A
  • 30-40%

Since foleys are rarely placed in the OR, it is important to remind PACU nurses to use a bladder scanner/ ultrasound to check for urinary retention.

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16
Q

What is the dose for an “epi wash”?
What is the dose for a “neo wash”?

A
  • Epinephrine 0.2 - 0.3 mg
  • Neosynephrine 2-5 mcg
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17
Q

What LA will have a profound effect if vasoconstrictors are added to it?

A
  • Tetracaine

Bupivacaine and Lidocaine will have variable increases.

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18
Q

What is the prophylactic management of hypotension from alpha 2 adrenergic agonst like precedex or clonidine?

A
  • Give fluids (250-500 cc bolus)
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19
Q

If a craniotomy requires a trans-ethmoidal approach, what medication can be given to prevent the VX Mechansim?

A
  • Glycopyrrolate, Rubinol (↑ HR)
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20
Q

α2-adrenergic agonist neuraxial dosage
Clonidine
Dexmedetomidine

A

α2-adrenergic agonist neuraxial dosage
Clonidine 15-45 mcg
Dexmedetomidine 3 mcg

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21
Q

Opioid neuraxial dosage
Morphine
Fentanyl
Sufentanil

A

Opioid neuraxial dosage
Morphine 0.1-0.4 mg
Fentanyl 10-25 mcg
Sufentanil 2.5-10 mcg

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22
Q

Vasoconstrictor neuraxial dosage
Epinephrine
Phenylephrine

A

Vasoconstrictor neuraxial dosage
Epinephrine 0.2-0.3 mg
Phenylephrine 2-5 mcg

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23
Q

What are the factors affecting the uptake of LA in the neural space?

A
  • Concentration of the LA in the CSF. ( ↑ Concentration, ↑ uptake)
  • Surface Area of neural tissue (↑ SA, ↑ uptake)
  • Lipid content of the nerve (↑ Lipid content, ↑ uptake)
  • Blood flow of the nerve (↑ blood flow, ↑ uptake)
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24
Q

__________ is the clinical phenomenon referring to the temporal blockade of autonomic, sensory, and motor nerve fibers when using neuraxial local anesthetics.

A
  • Differential Block

B fibers are blocked first (sympathectomy), followed by sensory loss (C and A-delta fibers), and lastly motor loss. (motor fibers)

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25
Q

What is the clinical progression of the differential blockade?

A
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26
Q

When assessing for sensory after performing neuraxial anesthesia. Is it better to assess pain or temperature?

A
  • Be nice and assess temperature with a cold alcohol swap or a cold teaspoon.
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27
Q

For zones of differential blocks, the sympathetic level is ___ to ___, higher than the sensory level.

A
  • 2 to 6 levels

If the sensory level is T10, the sympathetic level could be as high as T4.

28
Q

For zones of differential blocks, the sensory level is _____ levels higher than the motor level.

A
  • 2 levels
29
Q

What function will return that indicates the patient is starting to recover for neuraxial anesthesia?

A
  • Return of motor function (wiggling toes)
30
Q

All LAs used in neuraxial anesthesia are eliminated by ______.

A
  • Reuptake (reabsorption) by vessels in the pia mater
31
Q

What is the clinical relevance of isoflurane when used for outpatient anesthesia?

A
  • Because isoflurane is lipophilic, the drug will have a slower reuptake d/t the high affinity for fat.
  • Therefore, turn isoflurane off earlier.
32
Q

For spinals, what are the most important drug factors that affect the LA distribution and block height?

A
  • Dose
  • Baracity
33
Q

What are the most important patient factors that affect the LA distribution and block height?

A
  • CSF volume
  • Advance age
  • Pregnancy
34
Q

What are the most important procedure factors that affect the LA distribution and block height?

A
  • Patient position
  • Epidural injection post-spinal (Epidural volume extension)
35
Q

What is an epidural injection post-spinal?

A
  • Epidural block performed after a spinal block.
  • This is also known as epidural volume extension
  • Usually reserved for longer cases (or new surgical residents)
36
Q

Volume x Concentration =

A
  • Dose
37
Q

What is the most reliable determinant of local anesthetic?

A
  • The Dose
38
Q

_______ is defined as the relationship between the densities of local anesthetics and the density of CSF

A
  • Baracity
39
Q

Define Isobaric

A
  • “Stays where you put it”
  • LA has the same density or specific gravity as CSF
  • Normal Saline
40
Q

Define Hypobaric

A
  • “Floats” up
  • LA has a density or specific gravity that is less than CSF
  • Sterile Water
41
Q

Define Hyperbaric

A
  • Settles to the dependent aspect of the subarachnoid space
  • LA has a density or specific gravity that is greater than CSF
  • Dextrose
42
Q

What type of LA anesthetic would you want to use for a hip or knee procedure (Iso/Hypo/Hyperbaric solution)?

A
  • Isobaric
43
Q

What type of LA anesthetic would you want to use for a C-section procedure (Iso/Hypo/Hyperbaric solution)?

A
  • Hyperbaric
44
Q

What type of LA anesthetic would you want to use for a hemoidectomy (Iso/Hypo/Hyperbaric solution)?

A
  • Hypobaric
45
Q

Dosing of Hyperbaric SAB in Non-Obstetric Patient

T4:
T10:
Sacral Level:

A

Dosing of Hyperbaric SAB in Non-Obstetric Patient

T4: 2 mL (usually 0.75% bupivacaine)
T10: 1.5 mL
Sacral Level: 1 mL

46
Q

The estimated ED50of hyperbaric bupivacaine with or without opioids ranged from ________.

A
  • 4.7 mg to 9.8 mg.
47
Q

The calculated ED95 of hyperbaric bupivacaine with or without opioids ranged from _________.

A
  • 8.8 mg to 15 mg.
48
Q

How can a hyperbaric solution control dermatome spread?

A
  • Dose
  • Positioning
49
Q

What physical characteristic is seen with a hyperbaric solution as the needle is aspirated to check for CSF and placement?

A
  • Swirl
50
Q

The isobaric solution is difficult to get a level above ________.

A
  • T10
51
Q

Small CSF volume correlates to ________ spread of La in intrathecal space.

A
  • extensive

Peak of the block is higher with lower CSF.

52
Q

What is barbotage?

A
  • A method of spinal anesthesia injects a small amount of anesthetic into the subarachnoid space, followed by the withdrawal of cerebrospinal fluid into the syringe.
  • Found not effective
53
Q

What are the physiological responses of a SAB?

A
  • CV - sympathectomy
  • Pulmonary - resp depression
  • GI and GUT - can be a mess
  • Thromboregulation (shivering)
54
Q

Preganglionic B fibers that maintain arterial and venous tone are blocked FIRST by neuraxial anesthesia. A ↓ sympathetic tone results in:

A
  • Arterial and Venous dilation
  • Decrease in venous return
  • Decrease in cardiac output
  • Increase in venous capacitance (venous pooling)
  • HYPOTENSION
  • Bradycardia
55
Q

What are the mechanisms that will cause bradycardia with autonomic blockade?

A
  • Inhibition of Bainbridge reflex
  • Bezold-Jarisch reflex
  • T1-T4 cardio accelerator block
56
Q

What drug can inhibit Bezold-Jarisch Reflex?

A
  • Ondansetron (Zofran)
57
Q

What fluids are used to prevent hypotension secondary to neuraxial anesthesia?

A
  • Isotonic fluids (NS, Osmolyte A, LR)
  • Preload with 1 L
  • Co-loading is given fluid during the procedure
  • Make sure the fluids are warm

Fluids with dextrose will pull fluids and increase urination, contributing to hypotension.

58
Q

How low can you let a patient’s HR go in the OR?

A
  • No lower than 50 bpm
59
Q

What is given to manage the BP if severe hypertension occurs from ephedrine or phenylephrine?

A
  • Vasodilators
  • Narcotics
  • Anxiolytics
60
Q

What is the result of a T4 thoracic level dermatome spread of LA?

A
  • Small decrease in vital capacity
  • Loss of abdominal muscle contraction in forced expiration
61
Q

High thoracic blockade can result in the blockade of ___________ muscles of respiration.

A
  • Accessory (can be pronounced with COPD patients)
62
Q

What is the treatment for a patient when they start experiencing exhalation issues from neuraxial anesthesia?

A
  • Oxygen
  • Position
  • Reassurance
63
Q

Nausea and vomiting from neuraxial anesthesia is secondary to what causes?

A
  • Hypotension and Bradycardia

Oftentimes, N/V preceeds hypotension and bradycardia

64
Q

Sympathetic outflow originates from what levels?

A
  • T6 to L1
65
Q

Sympathetic blockade above ________ affects bladder control.

A
  • T10, urinary sphincter tone relaxed
66
Q

How does neuraxial anesthesia affect thermoregulation?

A
  • Shivering d/t LA effect on the central thermoregulation center of the brain.
67
Q

What are ways to prevent shivering from neuraxial anesthesia?

A
  • Ondansetron 4-8 mg

Mar: Sem 3 - Principles I (Grayson) (24 decks)

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