Labor & Analgesia Pt. 2 (Exam III) Flashcards
(67 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
L4-5
What are the disadvantages of a continuous epidural? 5
- 10 - 15 min onset of analgesia (slow)
- Higher drug requirement
- ↑ Maternal LAST risk
- ↑ fetal drug exposure
- Risk of sacral “sparing” slow blockade.
What is the standard “test dose” used for epidurals?
Lidocaine 1.5% w/ 1:200k epi (3mls)
Change in HR indicates intravascular epinephrine.
What would intrathecal placement of an epidural present like when injecting your test dose?
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 are the disadvantages of a CSE (combined spinal epidural) ? 4
- ↑ 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? 4
- Faster onset than regular epidural
- Transdural migration of medications injected into epidural space
- More rapid anaglesia
- ↓ risk of maternal HoTN and fetal bradycardia compared to CSE.
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? 2
- Large dural puncture = PDPH
- Risk of other provider mistaking catheter for an epidural catheter instead of a spinal.
What types of pain do epidural local anesthetics treat?
examples of each.
- 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? What neurons are spared?
- Separation of motor & sensory effects
- Sparing of A-α motor neurons
What are the advantages of Bupivacaine? 4 (Hint: Compared to Lidocaine/Chlorprocaine)
- Differential Block
- Long duration
- No tachyphylaxis
- Safety (↓ placental transfer)
What are the disadvantages of neuraxial bupivacaine? 2
- 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 are the advantages of Ropivacaine? (To bupivacaine) 2
- Differential Block (even better than bupivacaine).
- Safety (less toxic than bupivacaine)
What are the disadvantages of ropivacaine? 2
- Slow onset (10 - 15 minutes)
- CV & Neuro toxicity
Why is lidocaine not routinely used for labor analgesia? 3
- Poor differential block
- Tachyphylaxis risk
- ↑ placental transfer / ion trapping
What is neuraxial lidocaine useful for? 2(3)
- Identification of non-functional catheter
- Need for rapid sacral analgesia
- Instrumented vaginal delivery/perineal repair
- Emergent operative delivery
What dose of neuraxial lidocaine is used for emergent operative delivery?
2% Lidocaine 10 - 20 mls w/ 2mls of Na⁺Bicarb
Bicarb (2mls) w/ 18mls of 2% Lido
What will bicarbonate do when paired with lidocaine in neuraxial anesthesia?
Speed up onset
Good for emergent operative delivery.
