Labor Anesthesia & Analgesia Pt3 Flashcards
(26 cards)
Name the anatomy pertinent to an epidural/spinal.
- Skin
- Subcutaneous tissue
- Supraspinous ligament
- Interspinous ligament
- Ligamentum flavum
- Epidural space
- Dura mater
What three interspinous spaces are typical for epidural placement?
L2-3
L3-4 (more common)
L4-5 (more common)
What are the disadvantages of a continuous labor epidural?
- 10 - 15 min onset of analgesia (slow)
- Higher drug volume requirement
- ↑ Maternal LAST risk
- ↑ fetal drug exposure
- Risk of sacral “sparing” slow blockade.
What is the standard “test dose” used for epidurals?
3mL Lidocaine 1.5% w/ 1:200k epi
What increased risks are associated with LOR using air?
- risk of patchy block
- risk for pneumocephalus
How would intrathecal placement of an epidural present when injecting your test dose?
- Motor blockade
- Leg numbness & warmth (Lidocaine 1.5% going intrathecal). Heavy and high spinal risk.
Can a test dose be administered during a contraction?
No because then the change in HR can’t be solely attributed to the test dose.
What effects would you expect to see with a test dose of lido/epi administered intravascularly?
- increased HR 20bpm within 1 min
- circumoral numbness or tinnitus
In 3cc of 1.5% lidocaine + 1:200k epi, how many mg of lidocaine and epi is there?
45mg lido
15mcg epi
3cc x 15mg/mL = 45mg
3cc x 5mcg/mL = 15mcg
What are the disadvantages of a CSE (combined spinal epidural) ?
- ↑ risk of fetal bradycardia
- ↑ risk of PDPH
- ↑ risk of neuraxial infection
- Uncertainty of proper epidural catheter placement (until spinal wears off).
Why can fetal bradycardia sometimes occur with CSE ?
- Due to sympathetic blockade & maternal HoTN.
What is a Dural Puncture Epidural?
Similar to CSE but no medications are injected into the spinal space.
What are the advantages of a Dural Puncture Epidural?
- Faster onset than regular epidural
- Transdural migration of medications injected into epidural space
- More rapid analgesia
- ↓ risk of maternal HoTN and fetal bradycardia compared to CSE.
What are the main disadvantages to single shot spinal anesthesia?
- limited duration of analgesia
- increase risk maternal HoTN and fetal bradycardia
- increased risk PDPH
- risk postpartum neuraxial infection
When is a continuous spinal utilized?
After a “Wet Tap”.
Accidental placement of epidural Tuohy into the spinal space.
What are the disadvantages of a continous spinal?
- Large dural puncture = PDPH
- Risk of other providers mistaking catheter for an epidural catheter instead of a spinal. (SAB doses are way smaller)
What types of pain do epidural local anesthetics treat?
- Visceral Pain: lower uterine & cervical distention
- Somatic Pain: Fetal birth canal descent
Which two LA’s are most commonly used for labor?
Bupivacaine & Ropivacaine
What is a differential block?
- Separation of motor & sensory effects
- Sparing of A-α motor neurons
greater differential block = more sensory block with less motor blockade (ideal)
What are the advantages of Bupivacaine?
- Differential Block
- Long duration
- No tachyphylaxis
- Safety (↓ placental transfer)
What are the disadvantages of neuraxial bupivacaine?
- Slow onset time (10 - 15 min)
- Risk of CV & neuro toxicity
How can the latency time of bupivacaine/ropivacaine be improved?
Addition of a lipophillic opioid.
What epidural dosing of bupivacaine is typical (for labor)?
0.0625 - 0.25%
10 - 20mls
What are the advantages of Ropivacaine?
- Differential Block (even better than bupivacaine).
- Safety (less toxic than bupivacaine)
