Exam 3: Labor & Analgesia Pt. 2 Flashcards
Absolute contraindications for epidural placement
- Refusal
- Uncooperative patient
- Uncontrolled hemorrhage w/ ↓volume
- Epidural site infection
- Bleeding issues/disorder
- Anticoagulated (usually there’s a policy for how long you have to wait based on the drug)
Rotten Urologists Hush Iconic Blushing Alcoholics
Relative contraindications for epidural placement
- elevated ICP
- LA allergy
- language barrier w/o interpreter
- severe fetal depression
- severe maternal cardiac disease
- active coagulopathy
- untreated systemic infection
- pre-existing neurologic deficit
- skeletal abnormalities
- hardware in spine
What are the risks associated with epidural placement that is too early in labor?
- ↑ risk for instrumented delivery (vacuum or forceps)
- Prolonged 2ⁿᵈ stage of labor
- Risk of ineffective epidural and need for replacement
Risks of placing the epidural too late
- pt cant get into a good position
- pt cant stay still anymore
- provider preference
Bailey considers “too late” when the head is crowning
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?
- 10 - 15 min onset of analgesia (slow)
- Higher drug requirement (volume block)
- ↑ Maternal LAST risk
- ↑ fetal drug exposure
- Risk of sacral “sparing”, slow blockade, hot spots, patchy block etc.
What is the standard “test dose” used for epidurals?
Lidocaine 1.5% w/ 1:200k epi (3mLs)
What tells you the catheter is intrathecal or intravascular when giving the test dose?
- Lidocaine tells you the catheter is intrathecal. Pt will feel leg numbness & warmth (Lidocaine 1.5% going intrathecal). Heavy and high spinal risk.
- Epi tells you the catheter is placed intravascular you will see HR increase 20 bpm within 1 min
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) ?
- ↑ risk of fetal bradycardia b/c of the more profound sympathectomy)
- ↑ risk of PDPH
- ↑ risk of neuraxial infection
- Uncertainty of proper epidural catheter placement (until spinal wears off).
What is a Dural Puncture Epidural?
Similar to CSE but no medications are injected into the spinal space.
The dura now has a very small hole
What are the advantages of a Dural Puncture Epidural?
- Faster onset than regular epidural b/c some med can get intrathecal
- Transdural migration of medications injected into epidural space
- More rapid anaglesia
- ↓ risk of maternal HoTN and fetal bradycardia compared to CSE.
Single shot spinal for labor duration?
Trick question, single shot spinals are very rarely used for labor because the labor may outlast the spinal - mostly used for c-sections
When is a continuous spinal utilized?
After a “Wet Tap”.
Accidental placement of epidural Tuohy into the spinal space.
Change your doses to spinal doses! huge risk for other providers accidentally overdosing
What are the disadvantages of a continous spinal?
- 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?
- Visceral Pain: lower uterine & cervical distention
- Somatic Pain: Fetal birth canal descent
Which two LA’s are most commonly used for labor?
Bupivacaine & Ropivacaine
Bupivacaine has a differential block, what is a differential block?
- Separation of motor & sensory effects
- Sparing of A-α motor neurons
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)
- latency is improved with lipophilic opioid
- Risk of CV & neuro toxicity
What epidural dosing of bupivacaine is typical?
0.0625 - 0.25%
10 - 20mls
lower concentration, larger volume
What are the advantages of Ropivacaine?
- Differential Block (even better than bupivacaine).
- Safety (less toxic than bupivacaine)
What are the disadvantages of ropivacaine?
- Slow onset (10 - 15 minutes)
- latency is improved with lipophilic opioid
- CV & Neuro toxicity
What epidural dosing of ropivacaine is typical?
- 0.1 - 0.2%
- 10 - 20mls
Why is lidocaine not routinely used for labor analgesia?
- Poor differential block (significant motor blockade)
- Tachyphylaxis risk
- ↑ placental transfer / ion trapping
What is neuraxial lidocaine useful for?
- 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.
What dose of lidocaine is used for identification of a non-functional catheter?
5 - 10mls of 2% Lidocaine
What dose of Lidocaine is used for rapid sacral analgesia?
0.5 - 1% Lidocaine 5-10mls
What dose of Lidocaine is used for an instrumented vaginal delivery or for perineal repair?
Lidocaine 1.5 - 2% +/- epinephrine (5-10mls)
What are the advantages and disadvantages of Chloroprocaine?
Advantages:
- Rapid onset
Disadvantages:
- Very short duration
- Poor differential blockade
- interferes with action bupivicaine and opioids
When is neuraxial chloroprocaine useful?
Emergent instrumented or operative delivery and/or perineal repair
What dose of chloroprocaine is used for emergent instrumented delivery?
10mls of 2-3% chloroprocaine
What are the benefits of neuraxial opioids?
- ↓ LA dosage (20 - 30% reduction)
- ↓ latency (lipophilic will have faster onset - fentanyl/sufentanil)
- ↑ analgesia
- ↑ duration of analgesia
Which neuraxial opioids will have a later onset (but provide postoperative pain relief) ?
Hydrophillic
Morphine.
What is the dose of neuraxial clonidine?
75 - 100 mcg
What are the advantages of neuraxial clonidine?
- Analgesic
- ↓ LA requirement
- ↑ block quality/duration
- No motor blockade
What are the disadvantages of neuraxial clonidine?
- Maternal HoTN & bradycardia
- Maternal sedation
What is the typical dose and concentration of neuraxial dexmedetomidine?
0.25 - 0.5 mcg/mL
What is precedex used for in neuraxial anesthesia?
- ↓ latency
- ↑ duration of block
- ↓ LA requirement
What adverse effects can occur with higher concentration of neuraxial dexmedetomidine?
Maternal sedation
What is the MOA of neuraxial Precedex?
- Suppressed C-fiber transmission
- Hyperpolarization of postsynaptic dorsal horn neurons.
What is typical dose of bupivacaine in a continuous epidural infusion?
0.05 - 0.125% Bupivacaine
8 - 15 mL/hr
What is typical dose of ropivacaine in a continuous epidural infusion?
- 0.08 - 0.2%
- 8 - 15 mL/hr
What is a PCEA? and what are the advantages?
Patient controlled epidural anesthetic (+/- background infusion)
- Less motor blockade
- Less dosing by provider
What is the main factor in determination of LA dosing for a spinal?
Patient height & level of anesthesia desired.
How many mg of bupivacaine is being administered to a patient receiving 1.7mls of 0.75% bupivacaine?
1.7 x 7.5 = 12.75mg Bupivacaine
.75% is hyperbaric, 0.5% is isobaric
Can opioids be used as a solo agent for neuraxial anesthesia?
Yes
Analgesia w/ no numbness, motor blockade, or sympathectomy.
More commonly used as an additive however.
blocks afferent input from A-delta and C fibers to the spinal cord
What is the concentration of hyperbaric bupivacaine?
0.75%
What is the concentration of isobaric bupivacaine?
0.5%
What is the isobaric concentration of spinal ropivacaine?
0.5%
Not commonly used.
What is the dose of spinal dexmedetomidine?
2.5 - 10mcg
What is the purpose of spinal dexmedetomidine ?
- Prolongs analgesia
- ↓ latency
What is spinal dose of epinephrine?
2.25 - 100mcg
What is the purpose of intrathecal epinephrine?
- Prolonged analgesia
- increased motor blockade with higher dosing (100-200mcg)
Why does hypotention happen with neuraxial anesthesia?
We are causing a massive sympathetic blockade
- preipheral vasodialation
- increased venous capacitance
- decreased venous return
Note from Bailey: the very first thing they will likely feel before becoming hypotensive is nausesa
How is neuraxial hypotension typically treated?
- IV fluids
- Positioning
- Vasopressors (last)
What vasopressor can really help if you keep having to redose and redose pressors?
25-50mg of ephedrine IM can really help steady out their HoTN
What is the most common complaint associated with neuraxial opioids?
Pruritus
Why does pruritus occur with neuraxial opioid administration?
Central μ-opioid receptors
What dose of diphenhydramine (Benadryl) is used for neuraxial opioid pruritus?
Trick question. Itching is not due to histamine release. Benadryl will not work.
What drug is used to treat neuraxial opioid pruritus?
Centrally acting μ-opioid antagonist
- Naloxone 40 - 80mcg IV
- Naltrexone 6mg PO
Partial Agonist-Antagonist
- Nalbuphine 2-5mg IV
- Butorphanol 1-2mg IV
What are the conservative treatment options for a “wet tap”?
- Caffeine
- Laying down (positioning)
- dark room
What are the more invasive treatment options for PDPH?
Epidural blood patch
Should CSF be reinjected after wet-tap occurs with a Tuohy needle?
No. ↑ risk for infection/pneumocephalus
Why is bupivacaine 0.75% not used for epidural blocks?
Risk for CV toxicity if injected
What are the mild/moderate signs/symptoms of LAST?
- Tinnitus
- Circumoral numbness
- Restlessness
- Difficulty speaking
What is the treatment for LAST?
1.5 mL/kg of the 20% Lipid emulsion bolus & benzodiazepines
What are the signs/symptoms of a high spinal?
- Agitation
- Dyspnea
- Inability to speak
- Profound hypotension leading to LOC
- Apnea
How is a high spinal treated?
- Ventilation assistance
- Volume resuscitation
- Vasopressors
Pinky/hand numbness is associated with what spinal level?
C8
Cardioaccelerator fibers originate from what spinal levels?
T1-T4
Diaphragmatic ennervation comes from which spinal levels?
C3-C5
Thumb numbness is associated with what spinal level?
C6
What are the signs/symptoms of a subdural block?
- Unexpectedly high blockade w/ patchiness
- Profound HoTN
- Minimal motor blockade
- May involve cranial nerves because of the cranial>caudal spread
- Horner’s syndrome
- Apnea
- LOC changes
