Neuraxial Pharmacology Flashcards
Bupivacaine 0.75% in 8.25% Dextrose
Hyperbaric
Lidocaine 5% in 7.5% dextrose
Hyperbaric
Tetracaine 0.5% in 5% dextrose
Hyperbaric
Procaine 10% in water
- still hyperbaric even in water b/c of the high concentration
Bupivicaine 0.5% in saline
Isobaric
Bupivicaine 0.75% in saline
Isobaric
Lidocaine 2% in saline
isobaric
Tetracaine 0.5% in saline
Isobaric
Bupivicaine 0.3% in water
Hypobaric
Lidocaine 0.5% in water
hypobaric
Tetracaine 0.2% in water
Hypobaric
Spinal Drug
Bupivicaine 0.5-0.75%
T10 Dose:
T4 Dose:
Onset:
Duration:
Duration w/ Epi:
- T10: 10-15 mg
- T4: 12-20 mg
- Onset: 4-8 min
- Duration: 130-220 min
- Duration w/ Epi: + 20-50%
Spinal Drug
Levobupivicaine 0.5%
T10 Dose:
T4 Dose:
Onset:
Duration:
- T10 Dose: 10-15 mg
- T4 Dose: 12-20 mg
- Onset: 4-8 min
- Duration: 140-230 min
Spinal Drug
Ropivacaine 0.5-1%
T10 Dose:
T4 Dose:
Onset:
Duration:
- T10 Dose: 12-18 mg
- T4 Dose: 18-25 mg
- Onset: 3-8 min
- Duration: 80-210 min
Spinal Drug
2-Chloroprocaine 3%
T10 Dose:
T4 Dose:
Onset:
Duration:
T10 Dose: 30-40 mg
T4 Dose: 40-60 mg
Onset: 2-4 min
Duration: 40-90 min
Spinal Drug
Tetracaine 0.5-1%
T10 Dose:
T4 Dose:
Onset:
Duration:
Duration w/ Epi:
T10 Dose: 6-10 mg
T4 Dose: 12-16 mg
Onset: 3-5 min
Duration: 90-120 min
Duration w/ Epi: + 20-50%
What is alkalinization?
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
What are the ways of speeding the onset of LA?
- pKa
- concentration (3%)
- alkalinization
Initial Epidural Dosing
1-2 mL/segment of
* L3/L4 – T4 = 10 segments (10-20mL)
* 0.75% = 7.5 mg/mL (15mg = 2mL)
Top-up Epidural Dosing
50-75% of the initial dose
Timing of top-up epidural dose:
- before the block decreases > 2 dermatomes
- ex: T4 block - sensory check lowered to T6 = give another dose
How many mL should we use for thoracic epidural and why?
1 mL/segment – it is a smaller area and has greater spread
What characteristic of the drug determines how dense or strong the epidural block is?
Example?
- drug concentration determines block density
- ex: walking epidural w/ low concentration of drug
Epidural Drug
2-Chloroprocaine 3%
Onset:
Duration:
Epidural surgical analgesia:
Onset: 5-15 min
Duration: 30-90 min
Epidural Surgical Analgesia: 3%
Epidural Drug
Ropivacaine 0.1-0.75%
Onset:
Duration:
Epidural Surgical Analgesia:
Onset: 15-20 min
Duration: 140-220 min
Epidural Surgical Analgesia: 0.75%
Epidural Drug
Bupivicaine 0.0625-0.5%
Onset:
Duration:
Epidural Surgical Analgesia:
Onset: 15-20 min
Duration: 160-220 min
Epidural Surgical Analgesia: 0.5%
Epidural Drug
Lidocaine 2%
Onset:
Duration:
Epidural Surgical Analgesia:
Onset: 10-20 min
Duration: 60-120 min
Epidural Surgical Analgesia: 2%
Epidural Drug
Levobupivicaine 0.0625-0.5%
Onset:
Duration:
Epidural Surgical Analgesia:
Onset: 15-20 min
Duration: 150-225 min
Epidural Surgical Analgesia: 0.5%
What is the purpose of neuraxial adjuncts?
- provide post op analgesia
- extend the duration of the block
- improves density of the block
What are the 3 main classes of drugs that are neuraxial adjuncts?
- Opioids
- Alpha-2 Agonists
- Vasopressors
Opioids
Sufentanil
Intrathecal Dose:
Epidural Dose:
Epidural gtt Dose:
- lipophilic
1. Intrathecal: 5-10mcg
2. Epidural Dose: 25-50mcg
3. Epidural infusion: 10-20mcg/hr
Opioids
Fentanyl
Intrathecal Dose:
Epidural Dose:
Epidural gtt Dose:
- Lipophilic
1. Intrathecal: 10-20mcg
2. Epidural Dose: 50-100mcg
3. Epidural infusion: 25-100mcg/hr
Opioids
Hydromorphone
Intrathecal yes or no?
Epidural Dose:
Epidural gtt Dose:
- Hydrophilic
1. NO INTRATHECAL
2. Epidural Dose: 0.5-1mg
3. Epidural infusion: 0.1-0.2 mg/hr
Opioids
Meperidine
Intrathecal Dose:
Epidural Dose:
Epidural gtt Dose:
- hydrophilic
1. intrathecal dose: 10 mg
2. Epidural dose: 25-50 mg
3. Epidural infusion: 10-60 mg/hr
Opioids
Morphine
Intrathecal Dose:
Epidural Dose:
Epidural gtt dose:
- hydrophilic
1. Intrathecal dose: 0.25-0.30 mg
2. Epidural Dose: 2-5 mg
3. Epidural infusion: 0.1-1 mg/hr
Treatment of Opioid induced Pruritis
- Benadryl 25-50 mg
- Naloxone 0.1 mg IV
- Buprenex/Buprenorphine (mixed agonist/antagonist)
Opioid induced pruritis prophylaxis
- morphine <300mcg
- Ondansetron 4mg
- Nubain (Nalbuphine) 2.5-5 mg IV
Opioid SE
What dose of morphine is associated w/ less n/v?
50-100 mcg
Opioid SE
Tx of Opioid induced n/v
- Ondansetron (5HT-3 antagonist)
- Narcan 0.1mg
- Phenergan 12.5-25 mg
Opioid SE
What causes urinary retention?
- relaxation of detrusor muscle (30-40%)
What A-2 agonists can be used as neuraxial adjuncts?
MOA?
- Clonidine 15-45 mcg
- Dexmedetomidine 3 mcg
- MOA: intensifies and prolong sensory/motor blockade by ~1hr
Neuraxial Adjuncts
What vasoconstrictors can be given as an adjunct?
MOA?
- Epi Wash (0.2-0.3 mg)
- Phenyelphrine 2-5 mg
- works better w/ Tetracaine
- MOA: prolongs action of LA (reduced blood flow)
