Class 2 Analgesia & Pharmacology Flashcards
Describe the 1st stage pain pathway, and what dermatomes they are associated with.
- Lower uterine from contractions
- T10 - L1
Describe the 2nd stage pain pathway and it’s associated dermatomes.
- Perineal structure via pudenal nerve
- S2-S4 (not covered by epidural)
Opioids that cross the placenta can do what 2 things to the fetus?
- Loss of beat to beat variability
- Decreased movement
Name the 4 PCA advantages
- Satisfaction scores
- Less neonatal depression
- Less nausea
- Less maternal respiratory depression
Why is morphine not used?
-increased risk of respiratory depression r/t Immature BBB in baby
Demerol (meperidine) concerns
- Nausea and vomiting
- Baby respiratory depression unlikely if given < 1hr prior to delivery
- contraindicated with seizure / or renal failure (metabolite)
Fentanyl concerns
- Rapid placenta transfer
- resp depression longer than analgesia benefits
Nubain concerns
- Ceiling effect on respiratory depression
- Dysphoria
- treats opioid induced puritis
Stadol concerns
- Sedation
- Ceiling effect on resp depression
- better analgesic profile than fentanyl
Volatile agent concerns
- Rarely used
- pulmonary aspiration risk
- decreased uterine tone
- Supplement to nerve block
When is a pudenal block used, and on what patients?
- 2nd stage of labor
- pts with contraindication of neuraxial block
Risk of Pudenal block
- Fetal injury
- Infection
- Hematoma
when is a paracervical block used? What pain does it help with?
- When epidural cannot be achieved
- 1st stage labor
What are the complications of paracervical block?
- Uterine artery injection,
- fetal LA toxicity,
- nerve injury,
- hematoma
Ester local anesthetics.
- PABA
- Metabolized by plasma cholinesterase
- PABA metabolite is an allergen
- No previous “I”
Amide local anesthetic tidbits
- Metabolized by liver
- No PABA, allergic reactions rare
- 2 “i”s
Local anesthetics site of action?
-Neuronal cell membrane sodium channel
What determines the speed of Local anesthetic onset?
-pKa
To have a faster onset you would want pKa closer or farther away from physiological pH?
Closer
How can you artificially raise pH, to be closer to pKa?
-Add bicarb
Once across the membrane what form of drug is responsible for receptor binding and blockade?
-Polar form