Pharm Review - Regional & CSE Labor Analgesia Flashcards
What are the 3 most common LAs we will use for regional blocks?
- Lidocaine
- Bupivacaine
- Ropivacaine
Which LA has a faster onset but shorter DOA?
Lidocaine
Which LAs (2) have a slower onset but longer DOA?
Ropivavaine & Bupivacaine
Cardiac Toxicity Risk ↑
What is the main determinant of DOA for LAs?
- protein binding % of the LA
What is the main determinant of potency for LAs?
- lipid solubility of the LAs
What 6 medications can we give to prolong DOA of LAs?
- Epinephrine
- Dexmedetomidine
- Magnesium
- Clonidine
- Ketamine
- Decadron
What 2 things can we do to increase the onset of LAs?
- Add HCO3 - not common
- combine a short acting and long acting LA
Lidocaine Max (mg/kg)
w/o Epi:
w/ Epi:
- w/o: 5mg/kg
- w/: 7mg/kg
Prilocaine Max Dose (mg/kg)
w/o Epi:
w/ Epi:
- w/o: 6mg/kg
- w/: 8.5mg/kg
Mepivacaine Max Dose (mg/kg)
w/o Epi:
w/ Epi:
- w/o: 5mg/kg
- w/: 7mg/kg
Bupivacaine Max Dose (mg/kg)
w/o Epi:
w/ Epi:
- w/o: 2.5mg/kg
- w/: 2.5mg/kg
Ropivacaine Max Dose (mg/kg)
w/o Epi:
w/ Epi:
- w/o: 3mg/kg
- w/: 4mg/kg
Procaine Max Dose (mg/kg)
w/o Epi:
w/ Epi:
- w/o: 7mg/kg
- w/: 8.5mg/kg
Chloroprocaine Max Dose (mg/kg)
w/o Epi:
w/ Epi:
- w/o: 6mg/kg
- w/: 14mg/kg
Tetracaine Max Dose (mg/kg)
w/o Epi:
w/ Epi:
- w/o: 3mg/kg
- w/: 3mg/kg
CSE Labor Analgesia
Bupivacaine Dosing
Epidural:
Spinal:
E: 0.0625 - 0.125%
S: 1.25 - 2.5 mg
CSE Labor Analgesia
Ropivacaine Dosing
Epidural:
Spinal:
- E: 0.08 - 0.2%
- S: 2.5 - 4.5mg
CSE Labor Analgesia
Lidocaine w/ Epi Dosing
Epidural:
Spinal:
- E: 2% in 5mL bolus
- S: none
CSE Labor Analgesia
Fentanyl Dosing
Epidural:
Spinal:
- E: 50-100mcg
- S: 10-25mcg
CSE Labor Analgesia
Sufentanil Dosing
Epidural:
Spinal:
- E: 5 - 10mcg
- S: 1.5 - 5mcg
CSE Labor Analgesia
Morphine Dosing
Epidural:
Spinal:
- E: none
- S: 0.1 - 0.2 mg
What 5 LAs are amides?
2 Is
1. Lidocaine
2. Prilocaine
3. Mepivacaine
4. Bupivacaine
5. Ropivacaine
What 3 LAs are Esters?
- Procaine
- Chloroprocaine
- Tetracaine
Lidocaine dosing
IV bolus:
IV gtt:
- IV bolus: 1-2mg/kg IV over 2-4min
- IV gtt: 1-2mg/kg/hr
stop in 12-72hrs
Lidocaine Concentration → Effect
1-5mcg/mL =
Analgesia
Lidocaine Concentration → Effect
5-10mcg/mL =
- circum-oral numbness
- tinnitus
- skeletal muscle twitching
- HoTN
- myocardial depression
Lidocaine concentration → Effect
10-15mcg/mL =
- seizures
- unconsciousness
Lidocaine Concentration → Effect
15-25mcg/mL =
- Apnea
- Coma
Lidocaine Concentration → Effect
> 25mcg/mL
- CV depression
How many nodes of Ranvier need to be blocked?
- 3 nodes = 1cm
How are amide LAs metabolized?
- CYP enzymes - Hepatic
How are ester LAs metabolized?
- Hydrolysis - plasma cholinesterase enzymes
What ester LA is the one that IS metabolized in the liver?
Cocaine
Do Esters or Amides cause allergic reaction?
Ester
Which class of LAs is more likely to cross the placenta?
Amides
* non-ionized crosses
* Cautious w/ ion trapping
The metabolites of which LAs can lead to methemoglobinemia?
Lidocaine, Benzocaine, Prilocaine
Methylene blue dose to tx methemoglobinemia:
- 1-2mg/kg
- max: 7-8 mg/kg
T/F: We can give pregnant women Mepivacaine
False: long E 1/2 time in fetus
What LA is used to test plasma cholinesterase activity?
- Dibucaine
- MOA: inhibits activity of normal butyrylcholinesterase
If a Dibucaine level is low, what drug should we avoid giving?
- Succinylcholine - they won’t metabolize it
Epi Concentration
1:200,000
- 1,000,000/200,000 = 5mcg/mL
Epi Concentration
1:500,000
- 1,000,000/500,000 = 2mcg/mL
Epi Concentration
1:10,000
- 1,000,000/10,000 = 100mcg/mL
Epi Concentration
1:1,000
- 1,000,000/1,000 = 1,000mcg/mL
LA Strengths
0.25% =
2.5mg/mL
LA Strengths
0.5% =
- 5mg/mL
LA Strengths
1% =
- 10mg/mL
LA Strengths
2% =
- 20mg/mL
LA Strengths
4% =
- 40mg/mL
What does LTA stand for?
Laryngotracheal atomizer (Lidocaine)
What is the Lidocaine dose for Tumescent Liposuction?
- Lido w/ Epi: 35-55 mg/kg
- diluted Lido: 0.05% - 0.10%
- Epi: 1:100,000
What are 5 absolute contraindications to Neuraxial?
- Coagulopathy
- Pt refusal
- site infection
- Infection
- severe valvular heart dz
Is a spinal or epidural volume dependent?
- Epidural
Spinal is dose-dependent
Where does the spinal cord end?
Adult:
Pedi:
- A: L1
- P: L3
Desired dermatome level for peri-anal/anal surgery (saddle block):
- S2-S5
Desired dermatome level for foot/ankle surgery:
L2
Desired dermatome level for Thigh/lower leg/knee surgery:
L1
Desired dermatome level for vaginal delivery, uterine, hip procedure, tourniquet pain, and TURP
- T10
Desired dermatome level for scrotum surgery:
S3
Desired dermatome level for penile surgery:
- S2
Desired dermatome level for testicular procedures:
- T8
Desired dermatome level for Urologic, gynecologic, & lower abdominal procedures:
- T6
Desired dermatome level for C-section & upper abdominal surgery:
- T4
At what level does a “sympathectomy” occur?
T1-T4
What 2 medications should we always have ready when doing a spinal/epidural?
- Ephedrine (HR low)
- Neosynephrine (HR high)
What is a co-loading dose of fluids?
- 15mL/kg during the procedure
- NS/isotonic solution
These medications/fluids can be used to Tx spinal anesthetic HoTN
- Vasopressors
- Anticholinergics (Atropine)
- Crystalloids - Colloids
Organize the different regional anesthetic techniques that result in highest blood concentrations → lowest concentration
Highest → Lowest
1. Intravenous
2. Tracheal
3. Intercostal
4. Caudal
5. Paracervical
6. Epidural
7. Brachial
8. Sciatic
9. Subcutaneous
isobaric density:
- density equal to CSF - stays in place
hyperbaric density:
- density > CSF - sinks in the CSF
hypobaric density:
- density < CSF - rises in the CSF
Bupivacaine 0.5%-0.75%
T10 dose:
T4 dose:
- T10: 10-15mg
- T4: 12-20mg
Ropivacaine 0.5-1%
T10 dose:
T4 dose:
- T10: 12-18mg
- T4: 18-25mg
What is the initial volume for epidural dosing?
1-2mL/segment
What is the top-up vol. dosing for epidural?
- 50-75% of initial dose
↓ by 2 dermatome levels
LA Onset & Duration: fastest → slowest & shortest → longest
Onset fastest → slowest & DOA shortest → longest:
1. 2-Chloroprocaine
2. Lidocaine
3. Ropivacaine
4. Bupivacaine
5. Levobupivacaine
Opioid Epidural Infusion Dosing
Sufentanil
10-20mcg/hr
Opioid Epidural Infusion Dosing
Fentanyl
25-100mcg/hr
Opioid Epidural Infusion Dosing
Hydromorphone
0.1-0.2 mg/hr
Opioid Epidural Infusion Dosing
Meperidine (Demerol)
- 10-60 mg/hr
Opioid Epidural Infusion Dosing
Morphine
- 0.1-1 mg/hr
Dexmedetomidine dosing for spinal/epidural:
3 mcg
Clonidine dosing for epidural/spinal:
15-45mcg
Epinephrine dosing w/ LA:
- 0.2-0.3mg “epi wash”
Phenylephrine dosing w/ LA:
2-5mg
T/F: Neuraxial is contraindicated in pts on thrombolytic therapy
True!
What is the most cardiotoxic LA?
- Bupivacaine
LAST management:
- airway mgmt
- bzd for seizures
- modified ACLS (cautious w/ epi)
- Lipid emulsion 20%
What is the epidural test dose?
3mL of 1.5% Lidocaine w/ 1:200,000 Epi
Recommended “Top Up” time for Lidocaine:
60min
Top up time for Bupivacaine & Ropivacaine
120min
