L6: Epidurally Administered Drugs In SA (Garcia)

Question 1

Which drug ideal for epidurals?

Answer 1

Morphine

• least lipid soluble
• stays in tissues longer
• PF best b/c no neurotoxic effect

Question 2

Most commonly blocked spaces on spine

Answer 2

L7 and S1 (block significant portion of pelvic limb(s))

Question 3

Neurostimulating catheter

Answer 3

• used to block different areas of the body by traveling to LS space to area you want to block
• catheter guided through spinal canal

Question 4

Duration of bupivacaine

Answer 4

1.5-2hrs of anesthesia, 4-6hrs of analgesia

Question 5

Duration of ropivacaine

Answer 5

(Same as bupivacaine)
1.5-2 hrs of anesthesia, 4-6 hrs of analgesia

• can last longer at site since doesn’t vasodilate like bupivacaine does
• may have intrinsic vasoconstrictive effect

Question 6

Duration of lidocaine

Answer 6

45 min. - 1 hr. Of anesthesia, 2-3 hrs of analgesia

-very short-acting

Question 7

Major side effect of local anesthetics

Answer 7

Hypotension

Question 8

Toxic dose of lidocaine

Answer 8

16 mg/kg

Question 9

Sciatic nerve blocks can last as long as:

Answer 9

12 hours (little vasculature in that area)

Question 10

Where should you give dexmed. IM?

Answer 10

In quads (not epaxials)

Question 11

Norepinephrine, phenylephrine, and high dose dopamine have ALPHA effects

Dobutamine has BETA effects and causes vasodilation

Answer 11

:)

Question 12

Duration of PF morphine

Answer 12

Up to 24 hrs of analgesia (greater if combined with local anesthetic)

Question 13

Duration of methadone

Answer 13

8-12 hrs (greater w/ local anesthetic combos)

Question 14

Duration of fentanyl

Answer 14

Up to 3 hrs? Or less

Question 15

Epidurals cause urinary retention due to parasympathetic blockade; must express bladder

Urticaria can be seen with opioid epidurals due to histamine release

Answer 15

:)

Question 16

Alpha 2 agonists used in epidurals

Answer 16

Dexmedetomidine
Clonidine
Xylazine

Question 17

Effect of alpha 2 agonists used in epidurals

Answer 17

• good analgesia (similar to opioids)
• some local anesthetic effect w/ xylazine
• CV effects (bradycardia, 2nd degree AV blocks)

Question 18

Ketamine as an epidural agent

Answer 18

• short analgesia when given alone
• can prolong effects of local anesthetics
• not good enough alone
• may be useful as an NMDA antagonist for chronic pain

Question 19

Use of vasoconstrictors in epidurals

Answer 19

Ie. Epinephrine

• may prolong duration of action, but may not
• more effective in drugs that cause severe vasodilation and short duration (lidocaine)

Question 20

Complications of epidurals

Answer 20

• spread
• cardiac depression
• vasodilation
• resp. Arrest
• bleeding
• root or spinal cord damage
• IV injection
• death

Question 21

Advantages of epidurals

Answer 21

• sparing effect in other drugs
• less systemic use of other analgesics
• less systemic effects
• can provide anesthesia and analgesia for long periods of time
• low morbidity