Class 2 Analgesia & Pharmacology

Question 1

Describe the 1st stage pain pathway, and what dermatomes they are associated with.

Answer 1

• Lower uterine from contractions

- T10 - L1

Question 2

Describe the 2nd stage pain pathway and it’s associated dermatomes.

Answer 2

• Perineal structure via pudenal nerve

- S2-S4 (not covered by epidural)

Question 3

Opioids that cross the placenta can do what 2 things to the fetus?

Answer 3

• Loss of beat to beat variability

- Decreased movement

Question 4

Name the 4 PCA advantages

Answer 4

• Satisfaction scores
• Less neonatal depression
• Less nausea
• Less maternal respiratory depression

Question 5

Why is morphine not used?

Answer 5

-increased risk of respiratory depression r/t Immature BBB in baby

Question 6

Demerol (meperidine) concerns

Answer 6

• Nausea and vomiting
• Baby respiratory depression unlikely if given < 1hr prior to delivery
• contraindicated with seizure / or renal failure (metabolite)

Question 7

Fentanyl concerns

Answer 7

• Rapid placenta transfer

- resp depression longer than analgesia benefits

Question 8

Nubain concerns

Answer 8

• Ceiling effect on respiratory depression
• Dysphoria
• treats opioid induced puritis

Question 9

Stadol concerns

Answer 9

• Sedation
• Ceiling effect on resp depression
• better analgesic profile than fentanyl

Question 10

Volatile agent concerns

Answer 10

• Rarely used
• pulmonary aspiration risk
• decreased uterine tone
• Supplement to nerve block

Question 11

When is a pudenal block used, and on what patients?

Answer 11

• 2nd stage of labor

- pts with contraindication of neuraxial block

Question 12

Risk of Pudenal block

Answer 12

• Fetal injury
• Infection
• Hematoma

Question 13

when is a paracervical block used? What pain does it help with?

Answer 13

• When epidural cannot be achieved

- 1st stage labor

Question 14

What are the complications of paracervical block?

Answer 14

• Uterine artery injection,
• fetal LA toxicity,
• nerve injury,
• hematoma

Question 15

Ester local anesthetics.

Answer 15

• PABA
• Metabolized by plasma cholinesterase
• PABA metabolite is an allergen
• No previous “I”

Question 16

Amide local anesthetic tidbits

Answer 16

• Metabolized by liver
• No PABA, allergic reactions rare
• 2 “i”s

Question 17

Local anesthetics site of action?

Answer 17

-Neuronal cell membrane sodium channel

Question 18

What determines the speed of Local anesthetic onset?

Answer 18

-pKa

Question 19

To have a faster onset you would want pKa closer or farther away from physiological pH?

Answer 19

Closer

Question 20

How can you artificially raise pH, to be closer to pKa?

Answer 20

-Add bicarb

Question 21

Once across the membrane what form of drug is responsible for receptor binding and blockade?

Answer 21

-Polar form

Question 22

What dictates the onset, quality and duration of a Local Anesthetic?

Answer 22

-Total dose

Question 23

increasing dose =

Answer 23

faster onset and longer duration

Question 24

How do vasoconstrictors effect LA?

Answer 24

• prevent absorption

- More available for blockade

Question 25

How does temperature effect LA?

Answer 25

-Warm LA reduces onset time

Question 26

How does pregnancy effect LA?

Answer 26

- Smaller amounts are required | - Faster onset

Question 27

Small and poorly myelinated nerves, like type ____ fibers are ______ ______ susceptible to blockade.

Answer 27

- C | - More rapidly

Question 28

Large, myelinated nerves like type ____ fibers require ______ concentrations of LA for blockade.

Answer 28

- A | - Higher

Question 29

Local Anesthetic used for labor epidural.

Answer 29

- Bupivicaine - Ropivacaine - Lidocaine

Question 30

Local Anesthetic used for operative epidural.

Answer 30

- Lidocaine | - 2-chloroprocaine

Question 31

Local anesthetics used for OB spinal anesthesia?

Answer 31

- Tetracaine | - Bupivacaine

Question 32

Lidocaine concerns

Answer 32

- Not for continuous infusion - Test epidural catheter function - Motor block - activate epidural for C-section - Short duration

Question 33

2-chloroprocaine concerns

Answer 33

- only ester used in epidural space - Rapid onset / short duration - Large motor block - low risk of toxicity

Question 34

2-chloroprocaine will interfere with the analgesic effects of what med?

Answer 34

-Epidural fentanyl

Question 35

Bupivacaine concerns (used at Hamot)

Answer 35

- Long duration | - Less motor block (can still feel contractions and push)

Question 36

What happens if a large does of bupivicaine is given IV?

Answer 36

- CV collapse | - Refractory V-tach/V-fib

Question 37

Benefits of levobupivicaine?

Answer 37

-less cardiotoxic

Question 38

Ropivicaine benefit and problem.

Answer 38

- Less cardio toxic | - 25% less potent

Question 39

What is the best lumbar level to cover in OB? Where should catheter be placed to achieve that level?

Answer 39

- T10 - S4 | - L3 - L4

Question 40

For 95% of OB, the spinal chord ends at? The other 5%?

Answer 40

- L1 | - L2/3

Question 41

What imaginary line passes between the iliac crests?

Answer 41

-Truffiers (about L3/4)

Question 42

Contraindications to neuraxial block?

Answer 42

- Patient refusal - Infection - Intracranial mass - Coagulopathy - Aortic stenosis - Spinal pathology - Hemodynamic instability

Question 43

On average the epidural space is how deep?

Answer 43

4.75 cm

Question 44

How much of the tip should be in the epidural space?

Answer 44

-5 cm

Question 45

What are the differences between spinal and epidurals?

Answer 45

- Spinal is one tissue layer deeper - Drugs given via spinal are 10x more potent - Spinals require smaller needle

Question 46

When is a subarachnoid block used?

Answer 46

- C-sections | - Not enough time for epidural

Question 47

Benefit and problem with combined spinal / epidural

Answer 47

- instant relief | - Cant test epidural catheter

Question 48

Local anesthetic Central nervous system toxicity problems?

Answer 48

- Tinnitus - Metallic taste - Light headedness - Circumoral numbness - Convulsions - LOC - Respiratory arrest

Question 49

Increase in what 2 things lower the seizure threshold?

Answer 49

- PaCO2 | - Acidosis

Question 50

How doe LA toxicity effect the CV system?

Answer 50

- Sodium channel inhibition - Decrease depolarization of purkinjes fiber and ventricle muscle - Decrease action potential - Decrease refractory period - Increased toxicity to bupivicaine and cocaine

Question 51

LA toxicity is treated by what?

Answer 51

-20% intralipid

Question 52

Subdural block is located where?

Answer 52

-Between dura and arachnoid matter

Question 53

A subdural block may involve what?

Answer 53

- Cervical roots - Cranial nerves - Trigeminal block - Horners syndrome