Neuraxial Pharmacology

Question 1

Bupivacaine 0.75% in 8.25% Dextrose

Answer 1

Hyperbaric

Question 2

Lidocaine 5% in 7.5% dextrose

Answer 2

Hyperbaric

Question 3

Tetracaine 0.5% in 5% dextrose

Answer 3

Hyperbaric

Question 4

Procaine 10% in water

Answer 4

• still hyperbaric even in water b/c of the high concentration

Question 5

Bupivicaine 0.5% in saline

Answer 5

Isobaric

Question 6

Bupivicaine 0.75% in saline

Answer 6

Isobaric

Question 7

Lidocaine 2% in saline

Answer 7

isobaric

Question 8

Tetracaine 0.5% in saline

Answer 8

Isobaric

Question 9

Bupivicaine 0.3% in water

Answer 9

Hypobaric

Question 10

Lidocaine 0.5% in water

Answer 10

hypobaric

Question 11

Tetracaine 0.2% in water

Answer 11

Hypobaric

Question 12

Spinal Drug

Bupivicaine 0.5-0.75%
T10 Dose:
T4 Dose:
Onset:
Duration:
Duration w/ Epi:

Answer 12

1. T10: 10-15 mg
2. T4: 12-20 mg
3. Onset: 4-8 min
4. Duration: 130-220 min
5. Duration w/ Epi: + 20-50%

Question 13

Spinal Drug

Levobupivicaine 0.5%
T10 Dose:
T4 Dose:
Onset:
Duration:

Answer 13

1. T10 Dose: 10-15 mg
2. T4 Dose: 12-20 mg
3. Onset: 4-8 min
4. Duration: 140-230 min

Question 14

Spinal Drug

Ropivacaine 0.5-1%
T10 Dose:
T4 Dose:
Onset:
Duration:

Answer 14

1. T10 Dose: 12-18 mg
2. T4 Dose: 18-25 mg
3. Onset: 3-8 min
4. Duration: 80-210 min

Question 15

Spinal Drug

2-Chloroprocaine 3%
T10 Dose:
T4 Dose:
Onset:
Duration:

Answer 15

T10 Dose: 30-40 mg
T4 Dose: 40-60 mg
Onset: 2-4 min
Duration: 40-90 min

Question 16

Spinal Drug

Tetracaine 0.5-1%
T10 Dose:
T4 Dose:
Onset:
Duration:
Duration w/ Epi:

Answer 16

T10 Dose: 6-10 mg
T4 Dose: 12-16 mg
Onset: 3-5 min
Duration: 90-120 min
Duration w/ Epi: + 20-50%

Question 17

What is alkalinization?

Answer 17

Adding 1mEq of NaHCO3 to 10mL LA
* increases the pH of LA
* increases concentration of non-ionized free base
* increases rate of diffusion of the drug
* increases the speed of onset of the drug

Question 18

What are the ways of speeding the onset of LA?

Answer 18

1. pKa
2. concentration (3%)
3. alkalinization

Question 19

Initial Epidural Dosing

Answer 19

1-2 mL/segment of
* L3/L4 – T4 = 10 segments (10-20mL)
* 0.75% = 7.5 mg/mL (15mg = 2mL)

Question 20

Top-up Epidural Dosing

Answer 20

50-75% of the initial dose

Question 21

Timing of top-up epidural dose:

Answer 21

• before the block decreases > 2 dermatomes
• ex: T4 block - sensory check lowered to T6 = give another dose

Question 22

How many mL should we use for thoracic epidural and why?

Answer 22

1 mL/segment – it is a smaller area and has greater spread

Question 23

What characteristic of the drug determines how dense or strong the epidural block is?

Example?

Answer 23

• drug concentration determines block density
• ex: walking epidural w/ low concentration of drug

Question 24

Epidural Drug

2-Chloroprocaine 3%
Onset:
Duration:
Epidural surgical analgesia:

Answer 24

Onset: 5-15 min
Duration: 30-90 min
Epidural Surgical Analgesia: 3%

Question 24

# Epidural Drug Ropivacaine 0.1-0.75% Onset: Duration: Epidural Surgical Analgesia:

Answer 24

Onset: 15-20 min Duration: 140-220 min Epidural Surgical Analgesia: 0.75%

Question 25

# Epidural Drug Bupivicaine 0.0625-0.5% Onset: Duration: Epidural Surgical Analgesia:

Answer 25

Onset: 15-20 min Duration: 160-220 min Epidural Surgical Analgesia: 0.5%

Question 25

# Epidural Drug Lidocaine 2% Onset: Duration: Epidural Surgical Analgesia:

Answer 25

Onset: 10-20 min Duration: 60-120 min Epidural Surgical Analgesia: 2%

Question 26

# Epidural Drug Levobupivicaine 0.0625-0.5% Onset: Duration: Epidural Surgical Analgesia:

Answer 26

Onset: 15-20 min Duration: 150-225 min Epidural Surgical Analgesia: 0.5%

Question 27

What is the purpose of neuraxial adjuncts?

Answer 27

* provide post op analgesia * extend the duration of the block * improves density of the block

Question 28

What are the 3 main classes of drugs that are neuraxial adjuncts?

Answer 28

1. Opioids 2. Alpha-2 Agonists 3. Vasopressors

Question 29

# Opioids Sufentanil Intrathecal Dose: Epidural Dose: Epidural gtt Dose:

Answer 29

* lipophilic 1. Intrathecal: 5-10mcg 2. Epidural Dose: 25-50mcg 3. Epidural infusion: 10-20mcg/hr

Question 30

# Opioids Fentanyl Intrathecal Dose: Epidural Dose: Epidural gtt Dose:

Answer 30

* Lipophilic 1. Intrathecal: 10-20mcg 2. Epidural Dose: 50-100mcg 3. Epidural infusion: 25-100mcg/hr

Question 31

# Opioids Hydromorphone Intrathecal yes or no? Epidural Dose: Epidural gtt Dose:

Answer 31

* Hydrophilic 1. NO INTRATHECAL 2. Epidural Dose: 0.5-1mg 3. Epidural infusion: 0.1-0.2 mg/hr

Question 32

# Opioids Meperidine Intrathecal Dose: Epidural Dose: Epidural gtt Dose:

Answer 32

* hydrophilic 1. intrathecal dose: 10 mg 2. Epidural dose: 25-50 mg 3. Epidural infusion: 10-60 mg/hr

Question 33

# Opioids Morphine Intrathecal Dose: Epidural Dose: Epidural gtt dose:

Answer 33

* hydrophilic 1. Intrathecal dose: 0.25-0.30 mg 2. Epidural Dose: 2-5 mg 3. Epidural infusion: 0.1-1 mg/hr

Question 34

Treatment of Opioid induced Pruritis

Answer 34

1. Benadryl 25-50 mg 2. Naloxone 0.1 mg IV 3. Buprenex/Buprenorphine (mixed agonist/antagonist)

Question 35

Opioid induced pruritis prophylaxis

Answer 35

1. morphine <300mcg 2. Ondansetron 4mg 3. Nubain (Nalbuphine) 2.5-5 mg IV

Question 36

# Opioid SE What dose of morphine is associated w/ less n/v?

Answer 36

50-100 mcg

Question 37

# Opioid SE Tx of Opioid induced n/v

Answer 37

1. Ondansetron (5HT-3 antagonist) 2. Narcan 0.1mg 3. Phenergan 12.5-25 mg

Question 38

# Opioid SE What causes urinary retention?

Answer 38

* relaxation of detrusor muscle (30-40%)

Question 39

What A-2 agonists can be used as neuraxial adjuncts? MOA?

Answer 39

* Clonidine 15-45 mcg * Dexmedetomidine 3 mcg * MOA: intensifies and prolong sensory/motor blockade by ~1hr

Question 40

# Neuraxial Adjuncts What vasoconstrictors can be given as an adjunct? MOA?

Answer 40

1. Epi Wash (0.2-0.3 mg) 2. Phenyelphrine 2-5 mg * works better w/ Tetracaine * MOA: prolongs action of LA (reduced blood flow)