Induction Meds: Neuraxial Flashcards

1
Q

Where are receptors targeted with opioid neuraxial anesthesia?

A

Opioid receptors of the substantia gelatinosa.

S28*

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1
Q

What is general rule of dosing for epidural opioids?

A
  • Dose = 5 - 10 x normal

S29*

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2
Q

Diffusion of opioids across the _____ ______ results in systemic absorption.

A

dura mater

S30*

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3
Q

Where can opioids be injected during an epidural that results in systemic absorption?
What should be done if this occurs?

A
  • Epidural venous plexus
  • Add epi to the infusion.

S30*

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4
Q

What is Cephalad movement (in regards to epidurals)?

A

Cephalad Movement = the movement of drug/injectate up the spinal cord towards the brain.

S31*

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5
Q

What drug attribute decreases cephalad movement?

A

Lipid solubility

S31

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6
Q

This drug exhibits much more cephalad movement than __________.
Why is this?

A

Morphine > Fentanyl & Sufentanil

  • Fentanyl and it’s derivatives are much more lipid soluble and thus exhibit less cephalad movement.

-More in spinal cord < remains in CSF and migrate cephalad

S31

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7
Q

What can cause cephalad movement? (besides characteristics of drugs themselves)

A

Coughing and/or straining

S31

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8
Q

When would epidural admin/ CSF levels peak for the following drugs:
- Fentanyl
- Sufentanil
- Morphine

A
  • Fentanyl - 20min
  • Sufentanil - 6min
  • Morphine - 1-4 hours

S32*

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9
Q

When would epidural admin/ plasma levels peak for the following drugs:
- Fentanyl
- Sufentanil
- Morphine

A
  • Fentanyl - 5-10 min
  • Sufentanil - 5 min or less
  • Morphine - 10 - 15 min

S32*

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10
Q

When would intrathecal/cervical/CSF levels peak for the following drugs:
- Fentanyl
- Sufentanil
- Morphine

A
  • Fentanyl - N/A
  • Sufentanil - N/A
  • Morphine - 1 - 5 hours (due to cephalad movement)

S32

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11
Q

What is the most common side effect from neuraxial opioid administration?
Why does this occur?

A
  • Pruritis
  • Cephalad migration to trigeminal nucleus

most common in OB

S33

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12
Q

What are the treatments for pruritis induced by neuraxial opioids?

A
  • 10mg Propofol
  • Naloxone
  • Antihistamines
  • Gabapentin

S33

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13
Q

Name the list (its a lot) of side effects that can occur with neuraxial opioid administration.

A
  • Pruritis
  • N/V
  • Urinary retention
  • Respiratory depression
  • Sedation
  • Skeletal muscle rigidity
  • Herpes virus reactivation
  • Neonatal effects.

S33 to S35

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14
Q

If neuraxial opioids induced a reemergence of a herpes virus, how long would this occur after opioid administration?

A
  • 2 - 5 days

S35

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15
Q

What sign would indicate respiratory depression from neuraxial opioid administration?

What is the treatment?

A
  • ↓LOC from ↑CO₂
  • Naloxone 0.25 μg/kg/hr IV

S34

16
Q

Neuraxial Opioids can be used on what sites?

A
  1. Epidural
  2. Subarachnoid/Spinal/Intrathecal

S29*

17
Q

Which Neuraxial Opioid drug has slower onset but longer duration?

A

Morphine

S29