Induction Meds: Neuraxial

Question 1

Where are receptors targeted with opioid neuraxial anesthesia?

Answer 1

Opioid receptors of the substantia gelatinosa.

S28*

Question 1

What is general rule of dosing for epidural opioids?

Answer 1

• Dose = 5 - 10 x normal

S29*

Question 2

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

Answer 2

dura mater

S30*

Question 3

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

Answer 3

• Epidural venous plexus
• Add epi to the infusion.

S30*

Question 4

What is Cephalad movement (in regards to epidurals)?

Answer 4

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

S31*

Question 5

What drug attribute decreases cephalad movement?

Answer 5

Lipid solubility

S31

Question 6

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

Answer 6

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

Question 7

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

Answer 7

Coughing and/or straining

S31

Question 8

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

Answer 8

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

S32*

Question 9

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

Answer 9

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

S32*

Question 10

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

Answer 10

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

S32

Question 11

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

Answer 11

• Pruritis
• Cephalad migration to trigeminal nucleus

most common in OB

S33

Question 12

What are the treatments for pruritis induced by neuraxial opioids?

Answer 12

• 10mg Propofol
• Naloxone
• Antihistamines
• Gabapentin

S33

Question 13

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

Answer 13

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

S33 to S35

Question 14

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

Answer 14

• 2 - 5 days

S35

Question 15

What sign would indicate respiratory depression from neuraxial opioid administration?

What is the treatment?

Answer 15

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

S34

Question 16

Neuraxial Opioids can be used on what sites?

Answer 16

1. Epidural
2. Subarachnoid/Spinal/Intrathecal

S29*

Question 17

Which Neuraxial Opioid drug has slower onset but longer duration?

Answer 17

Morphine

S29