Labor & Analgesia Pt. 2 (Exam III) Flashcards
1
Q
Name the anatomy pertinent to an epidural/spinal.
A
- Skin
- Subcutaneous tissue
- Supraspinous ligament
- Interspinous ligament
- Ligamentum flavum
- Epidural space
- Dura mater
2
Q
What layer is the Tuohy needle anchored in when doing an epidural?
A
- interspinous ligament
3
Q
What three interspinous spaces are typical for epidural placement?
A
L2-3
L3-4
L4-5
4
Q
What are the 5 disadvantages of a continuous epidural?
A
- 10 - 15 min onset of analgesia (slow)
- Higher drug requirement volume block
- ↑ Maternal LAST risk
- ↑ fetal drug exposure
- Risk of sacral “sparing”, hot spots, or slow blockade.
5
Q
What are 2 risks when using air for LOR?
A
- risk of patchy block
- risk for pneumocephalus
6
Q
What is the standard “test dose” used for epidurals?
A
Lidocaine 1.5% w/ 1:200k epi (3mls)
Change in HR indicates intravascular epinephrine.
7
Q
What would intrathecal placement of an epidural present like when injecting your test dose?
A
Leg numbness & warmth (Lidocaine 1.5% going intrathecal).
Heavy and high spinal risk.
8
Q
Can a test dose be administered during a contraction?
A
No because then the change in HR can’t be solely attributed to the test dose.
9
Q
How much Lidocaine & epi does each test dose (3mL) contain?
A
- 45mg Lido (1.5%)
- 15mcg Epi (1:200,000)
10
Q
What is a CSE?
A
Combined Spinal Epidural
* single shot intrathecal followed by placement of epidural catheter
11
Q
What are 5 advantages of the CSE?
A
- rapid onset analgesia (2-5min)
- low doses of LA & opioid
- continuous analgesia (epidural)
- epidural in place for C-section
- decreased incidence of failed epidural
12
Q
What are the 4 disadvantages of a CSE (combined spinal epidural) ?
A
- ↑ risk of fetal bradycardia
- ↑ risk of PDPH
- ↑ risk of neuraxial infection
- Uncertainty of proper epidural catheter placement (until spinal wears off).
13
Q
Why can fetal bradycardia sometimes occur with CSE ?
A
- Due to sympathetic blockade & maternal HoTN.
14
Q
What is a Dural Puncture Epidural?
A
Similar to CSE but no medications are injected into the spinal space.
15
Q
What are the advantages of a Dural Puncture Epidural?
A
- 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.
16
Q
What are the 2 disadvantages to a DPE?
A
- PDPH risk
- PP neuraxial infection risk
17
Q
What are 3 advantages to a SS spinal for labor?
A
- rapid onset analgesia
- immediate sacral analgesia
- low LA & opioid doses
18
Q
What are 4 disadvantages to a SS spinal for labor?
A
- limited duration of analgesia
- increased risk of maternal HoTN/fetal bradycardia
- increased risk of PDPH
- Increased risk of PP neuraxial infection
19
Q
When is a continuous spinal utilized?
A
After a “Wet Tap”.
Accidental placement of epidural Tuohy into the spinal space.
need lower doses than epidural
20
Q
What are the disadvantages of a continous spinal?
A
- Large dural puncture = PDPH
- Risk of other provider mistaking catheter for an epidural catheter instead of a spinal.
21
Q
What types of pain do epidural local anesthetics treat?
A
- Visceral Pain: lower uterine & cervical dilation
- Somatic Pain: Fetal descent into birth canal
22
Q
Which two LA’s are most commonly used for labor?
A
Bupivacaine & Ropivacaine
23
Q
What is a differential block?
A
- Separation of motor & sensory effects
- Sparing of A-α motor neurons
24
Q
What are the 4 advantages of Bupivacaine?
A
- Differential Block
- Long duration
- No tachyphylaxis
- Safety (↓ placental transfer)
25
What are the disadvantages of neuraxial bupivacaine?
- Slow onset time (10 - 15 min)
- Risk of CV & neuro toxicity
26
How can the latency time of bupivacaine/ropivacaine be improved?
Addition of a lipophillic opioid.
27
What epidural dosing of bupivacaine is typical?
0.0625 - 0.25%
10 - 20mls
28
With epidural dosing, lower concentration =
larger volume
29
What are the advantages of Ropivacaine?
- Differential Block (even better than bupivacaine).
- Safety (less toxic than bupivacaine)
30
What are the disadvantages of ropivacaine?
- Slow onset (10 - 15 minutes)
- CV & Neuro toxicity
31
What epidural dosing of ropivacaine is typical?
- 0.1 - 0.2%
- 10 - 20mls
32
Why is lidocaine not routinely used for labor analgesia?
- Poor differential block
- Tachyphylaxis risk
- ↑ placental transfer / ion trapping
33
What is neuraxial lidocaine useful for?
- Identification of non-functional catheter (2% x 5-10mL)
- Need for rapid sacral analgesia (0.5-1% x 5-10mL)
- Instrumented vaginal delivery/perineal repair (1.5-2% +/- epi)
- Emergent operative delivery (2% lido 18mL + 2mL bicarbonate)
34
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*
35
What will bicarbonate do when paired with lidocaine in neuraxial anesthesia?
Speed up onset
*Good for emergent operative delivery*.
36
What dose of lidocaine is used for identification of a non-functional catheter?
5 - 10mls of 2% Lidocaine
37
What dose of Lidocaine is used for rapid sacral analgesia?
0.5 - 1% Lidocaine 5-10mls
38
What dose of Lidocaine is used for an instrumented vaginal delivery or for perineal repair?
Lidocaine 1.5 - 2% +/- epinephrine (5-10mls)
39
What are the advantages and disadvantages of Chloroprocaine?
Advantages:
-Rapid onset
Disadvantages:
- Short duration
- Poor differential blockade
40
What are the disadvantages of chloroprocaine?
- Short duration of action
- Interferes with bupivacaine/opioids
41
When is neuraxial chloroprocaine useful?
Emergent instrumented or operative delivery and/or perineal repair
42
What dose of chloroprocaine is used for emergent instrumented delivery?
10mls of 2-3% chloroprocaine
43
What are the benefits of neuraxial opioids?
- ↓ LA dosage (20 - 30% reduction)
- ↓ latency
- ↑ analgesia quality
- ↑ duration of analgesia
44
Which opioids will have a faster onset?
Lipophillic (fentanil, sufentanil, etc)
45
Which neuraxial opioids will have a later onset (but provide postoperative pain relief) ?
Hydrophillic
*Morphine*.
46
What is the dose of neuraxial clonidine?
75 - 100 mcg
47
What are the 4 advantages of neuraxial clonidine?
- Analgesic
- ↓ LA requirement
- ↑ block quality/duration
- No motor blockade
48
What are the disadvantages of neuraxial clonidine?
- Maternal HoTN & bradycardia
- Maternal sedation
49
What is the typical dose of neuraxial dexmedetomidine?
0.25 - 0.5 mcg/mL
50
What is precedex used for in neuraxial anesthesia?
- ↓ latency
- ↑ duration of block
- ↓ LA requirement
51
What adverse effects can occur with higher concentration of neuraxial dexmedetomidine?
Maternal sedation & anxiolysis
52
What is the MOA of neuraxial Precedex?
- Suppressed C-fiber transmission
- Hyperpolarization of postsynaptic dorsal horn neurons.
53
What is typical dose of bupivacaine in a continuous epidural infusion?
0.05 - 0.125% Bupivacaine
**8 - 15 mL/hr**
54
What is typical dose of ropivacaine in a continuous epidural infusion?
- 0.08 - 0.2%
- 8 - 15 mL/hr
55
What is a PCEA?
Patient controlled epidural anesthetic
- Less motor blockade
- Less dosing by provider
56
What level of blockade is required for a C-section?
T6-T4
57
What level of blockade is required for labor?
T10
58
What is the main factor in determination of LA dosing for a spinal?
**Patient height & level of anesthesia desired**.
59
What variables affect the spread and duration of regional anesthesia?
1. Baricity
2. total dose
3. type of LA solution
4. injection site
5. patient positioning
60
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
61
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*.
62
What is the MOA of spinal opioids?
* block afferent input from A-delta & C fibers to spinal cord
63
What is the dose of hyperbaric bupivacaine?
0.75%
## Footnote
**heavier than CSF = sinks**
64
What is the dose of isobaric bupivacaine?
0.5%
## Footnote
**lighter than CSF = floats**
65
What is the isobaric dose of spinal ropivacaine?
0.5%
*Not commonly used*.
66
What is the dose of spinal dexmedetomidine?
2.5 - 10mcg
67
What is the purpose of spinal dexmedetomidine ?
- Prolongs analgesia
- ↓ latency
68
What is spinal dose of epinephrine?
2.25 - 100mcg
69
What is the purpose of intrathecal epinephrine?
- Prolonged analgesia
- increased motor blockade (with higher dosing)
70
What would a higher dose of spinal epinephrine (100 - 200mcg) do?
↑ motor blockade
71
What 6 things should we regularly assess in neuraxial?
1. Analgesia quality
2. Labor progress
3. Sensory level
4. Intensity of motor blockade
5. maternal v/s
6. FHR tracings
72
If close to delivery, what should we give to help with pain?
* dense block (push dose)
* 0.25% Bupivacaine
73
If early on in labor, what should we give to help with pain?
* bolus off of the pump
74
What are 3 medications & doses we can give to assess if an epidural is still working?
1. Fentanyl 50-100mcg (helps w/ hotspots)
2. Lidocaine 1-2% x 5-10mL (should make a dense block)
3. Bupivacaine 0.25% x 5-10mL (if later on in labor)
75
What is usually the 1st thing felt by the mom when she has HoTN?
Nausea
76
What are 4 physiolgoic causes of hypotension post-neuraxial?
1. sympathetic blockade
2. peripheral vasodilation
3. increased venous capacitance
4. decreased venous return
77
What is the *definition* of hypotension after neuraxial?
* SBP < 90-100 mmHg or 20-30% decrease in baseline SBP
78
How is neuraxial hypotension typically treated?
- IV fluids (caution in pre-eclampsia)
- Positioning (sit them up)
- Vasopressors (last)
79
What is the most common complaint associated with neuraxial opioids?
Pruritus
80
Why does pruritus occur with neuraxial opioid administration?
Central μ-opioid receptors
81
What dose of diphenhydramine (Benadryl) is used for neuraxial opioid pruritus?
Trick question. Itching is not due to histamine release. Benadryl will not work.
82
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
83
What are the conservative treatment options for a "wet tap"?
- Caffeine
- Laying down (positioning)
84
What are the more invasive treatment options for PDPH?
Epidural blood patch
85
Should CSF be reinjected after wet-tap occurs with a Tuohy needle?
**No**. ↑ risk for infection/pneumocephalus
86
Why is bupivacaine 0.75% not used for epidural blocks?
Risk for CV toxicity if injected
87
What are the mild/moderate signs/symptoms of LAST?
- Tinnitus
- Circumoral numbness
- Restlessness
- Difficulty speaking
88
What is the treatment for LAST?
1.5 mL/kg Lipid emulsion bolus & benzodiazepines
89
What are the 5 signs/symptoms of a high spinal?
- Agitation
- Dyspnea
- Inability to speak
- Profound hypotension
- Apnea
90
How is a high spinal treated?
- Ventilation assistance
- Volume resuscitation
- Vasopressors
## Footnote
**reverse trendelenburg to help spinal level regress**
91
Pinky/hand numbness is associated with what spinal level?
C8
92
Cardioaccelerator fibers originate from what spinal levels?
T1-T4
93
Diaphragmatic innervation comes from which spinal levels?
C3-C5
94
Thumb numbness is associated with what spinal level?
C6
95
What are the 6 signs/symptoms of a subdural block?
- Unexpectedly high blockade w/ patchiness
- Profound HoTN
- Minimal motor blockade
- Horner's syndrome
- Apnea
- LOC changes
