Labor Analgesia Lecture 2 and 3 Flashcards
1
Q
List the anatomy that the needle passes through when administering spinal anesthesia.
A
- Skin
- Subcutaneous tissue
- Supraspinous ligament
- Interspinous ligament
- Ligamentum flavum
- Epidural space
- Dura mater
2
Q
What three interspinous spaces are typical for epidural placement?
A
L2-3
L3-4
L4-5
3
Q
What are the disadvantages of a continuous epidural?
A
- 10 - 15 min onset of analgesia (slow)
- Higher drug requirement
- ↑ Maternal LAST risk
- ↑ fetal drug exposure
- Risk of sacral “sparing” slow blockade.
4
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.
5
Q
What would intrathecal placement of an epidural present like when injecting your test dose?
A
Lidocaine 1.5% going intrathecal:
Motor blockade w/in 3-5 mins
Leg numbness & warmth
Heavy and high spinal risk.
6
Q
What would intravascular placement of an epidural present like when injecting your test dose?
A
Epinephrine going intravascular:
increase in HR 20 bpm in 1 min
timing test dose between contractions (contractions can increase HR too)
Lidocaine intravascular:
May have circumoral numbness/tinnitus
7
Q
What are the 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).
8
Q
What is a Dural Puncture Epidural?
A
Similar to CSE but no medications are directly injected into the spinal space.
9
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.
10
Q
When is a continuous spinal utilized?
A
After a “Wet Tap”
Accidental placement of epidural Tuohy into the spinal space.
11
Q
What are the disadvantages of a continuous spinal?
A
- Large dural puncture = PDPH
- Risk of other provider mistaking catheter for an epidural catheter instead of a spinal.
12
Q
What types of pain do epidural local anesthetics treat?
A
- Visceral Pain: lower uterine & cervical distention
- Somatic Pain: Fetal birth canal descent
13
Q
Which two LA’s are most commonly used for labor?
A
Bupivacaine & Ropivacaine
14
Q
What is a differential block?
A
- Separation between motor & sensory effects
- Sparing of A-α motor neurons
15
Q
What are the advantages of Bupivacaine?
A
- Differential Block
- Long duration
- No tachyphylaxis
- Safety:
-↓ placental transfer
-↓ concentrations have ↓ toxicity risk
16
Q
What are the disadvantages of neuraxial bupivacaine?
A
- Slow onset time (10 - 15 min)
↳ onset improved with lipophilic opioid - Risk of CV & neuro toxicity
-binds to Na+ channels and slow to unbind
17
Q
How can the latency time of bupivacaine/ropivacaine be improved?
A
Addition of a lipophillic opioid.
18
Q
What epidural dosing of bupivacaine is typical?
A
0.0625 - 0.25%
10 - 20mls (lower concentration/higher vol)
19
Q
What are the advantages of Ropivacaine?
A
- Differential Block (even better than bupivacaine).
- Safety (less toxic than bupivacaine)
20
Q
What are the disadvantages of ropivacaine?
A
- Slow onset (10 - 15 minutes)
- CV & Neuro toxicity
21
Q
What epidural dosing of ropivacaine is typical?
A
- 0.1 - 0.2%
- 10 - 20mls
22
Q
Why is lidocaine not routinely used for labor analgesia?
A
- Poor differential block
- Tachyphylaxis risk
- ↑ placental transfer/ion trapping
23
Q
What is neuraxial lidocaine useful for?
A
- Identification of non-functional catheter
- Need for rapid sacral analgesia
- Instrumented vaginal delivery/perineal repair
- Emergent operative delivery
24
Q
What dose of neuraxial lidocaine is used for emergent operative delivery?
A
2% Lidocaine 10 - 20 mls w/ 2mls of Na⁺Bicarb
Bicarb (2mls) w/ 18mls of 2% Lido
25
What will bicarbonate do when paired with lidocaine in neuraxial anesthesia?
Speed up onset
*Good for emergent operative delivery*.
26
What dose of lidocaine is used for identification of a non-functional catheter?
5 - 10mls of 2% Lidocaine
27
What dose of Lidocaine is used for rapid sacral analgesia?
0.5 - 1% Lidocaine 5-10mls
28
What dose of Lidocaine is used for an instrumented vaginal delivery or for perineal repair?
Lidocaine 1.5 - 2% +/- epinephrine (5-10mls)
29
What are the advantages and disadvantages of Chloroprocaine?
Advantages:
-Rapid onset
- Short duration
- Poor differential blockade
Disadvantages:
-interferes with action of bupivacaine/opioids
30
When is neuraxial chloroprocaine useful? What dose is typical for this scenario?
Emergent instrumented or operative delivery and/or perineal repair
Dose:
-10mls of 2-3% chloroprocaine
31
What are the benefits of neuraxial opioids?
- ↓ LA dosage (20 - 30% reduction)
- ↓ latency (onset)
- improved quality of analgesia
- ↑ duration of analgesia
32
Which opioids will have a faster onset? What is an advantage of this?
Lipophillic (fentanil, sufentanil, etc)
-can be used to treat hot spots/patchy blocks
33
Which neuraxial opioids will have a later onset (but provide postoperative pain relief) ?
Hydrophillic
*Morphine*.
34
What is the dose of neuraxial clonidine?
75 - 100 mcg
35
What are the advantages of neuraxial clonidine?
- Analgesic
- ↓ LA requirement
- ↑ block quality/duration
- No motor blockade
36
What are the disadvantages of neuraxial clonidine?
- Maternal HoTN & bradycardia
- Maternal sedation
37
What is the typical dose of neuraxial dexmedetomidine?
0.25 - 0.5 mcg/mL
38
What are the benefits of precedex in neuraxial anesthesia?
- ↓ latency
- ↑ duration of block
- ↓ LA requirement
39
What adverse effects can occur with higher concentration of neuraxial dexmedetomidine?
Maternal sedation
40
What is typical dose of bupivacaine in a continuous epidural infusion?
0.05 - 0.125% Bupivacaine
**8 - 15 mL/hr**
41
What is typical dose of ropivacaine in a continuous epidural infusion?
- 0.08 - 0.2%
- 8 - 15 mL/hr
42
What is a PCEA?
Patient controlled epidural anesthetic
-may or may not have background infusion
- Less motor blockade
- significantly less dosing by provider
43
What is the main factor in determination of LA dosing for a spinal?
**Patient height & level of anesthesia desired**.
44
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
45
Although more commonly used as an additive, opioids may be used as a solo agent for neuraxial anesthesia. What effect do opioids as solo agent have in spinal? How do they provide this effect?
-Analgesia w/ no numbness, motor blockade, or sympathectomy.
-Blockade of afferent input from A delta and C fibers to spinal cord
-Efferent impulses unaffected
46
What is the dose of hyperbaric bupivacaine?
0.75%
47
What is the dose of isobaric bupivacaine?
0.5%
48
What is the isobaric dose of spinal ropivacaine?
0.5%
*Not commonly used*.
49
What is the dose of spinal dexmedetomidine?
2.5 - 10mcg
50
What is the purpose of spinal dexmedetomidine ?
- Prolongs analgesia
- ↓ latency
51
What is spinal dose of epinephrine?
2.25 - 100mcg
52
What is the purpose of intrathecal epinephrine?
- Prolonged analgesia
- increased motor blockade (with higher dosing)
53
What would a higher dose of spinal epinephrine (100 - 200mcg) do?
↑ motor blockade (this is an undesired effect)
54
What are the SBP changes that require intervention? How is neuraxial hypotension typically treated?
SBP <90-100 mmHg or 20-30% Decrease in baseline SBP
**fetal distress also indication for treatment**
- IV fluids
- Positioning
- Vasopressors (last)
55
What is the most common complaint associated with neuraxial opioids?
Pruritus
56
Why does pruritus occur with neuraxial opioid administration?
Central μ-opioid receptors
57
What dose of diphenhydramine (Benadryl) is used for neuraxial opioid pruritus?
Trick question. Itching is not due to histamine release. Benadryl will not work.
58
What drug is used to treat neuraxial opioid pruritus?
Centrally acting μ-opioid antagonist
- Naloxone 40 - 80mcg IV bolus or 1-2 mcg/kg/hr
- Naltrexone 6mg PO
59
What are the conservative treatment options for a "wet tap"?
- Caffeine
- Laying down (positioning)
60
What are the more invasive treatment options for PDPH?
Epidural blood patch
61
Should CSF be reinjected after wet-tap occurs with a Tuohy needle?
**No**. ↑ risk for infection/pneumocephalus
62
Why is bupivacaine 0.75% not used for epidural blocks?
Risk for CV toxicity if injected
63
What are the mild/moderate signs/symptoms of LAST?
- Tinnitus
- Circumoral numbness
- Restlessness
- Difficulty speaking
64
What is the treatment for LAST?
1.5 mL/kg Lipid emulsion bolus over 2-3 min & benzodiazepines
65
What are the signs/symptoms of a high spinal?
- Agitation
- Dyspnea
- Inability to speak
- Profound hypotension l/t Loss of consciousness
- Apnea
66
How is a high spinal treated?
- Ventilation assistance
- Volume resuscitation
- Vasopressors
67
Pinky/hand numbness is associated with what spinal level?
C8
68
Cardioaccelerator fibers originate from what spinal levels?
T1-T4
69
Diaphragmatic innervation comes from which spinal levels?
C3-C5
70
Thumb numbness is associated with what spinal level?
C8
71
What are the signs/symptoms of a subdural block?
- Unexpectedly high blockade w/ patchiness
- Profound HoTN
- Minimal motor blockade (onset 10-20 mins)
-cranial spread>caudal spread
- Horner's syndrome
- Apnea
- LOC possible
72
What are the risks associated with epidural placement that is too early in labor?
- ↑ risk for instrumented delivery
- Prolonged 2ⁿᵈ stage of labor
- Risk of ineffective epidural and need for replacement
73
What are the risks associated with epidural placement that is too late in labor?
-Patient can't get into good position
-patient can no longer stay still
74
List the 5 types of Neuraxial anesthesia?
1. Epidural (CLE) continuous labor epidural
2. Dural puncture epidural (DPE)
3. Combined Spinal-epidural (CSE)
4. Single shot spinal/intrathecal
5. Continuous spinal/intrathecal
75
What are the advantages of a continuous epidural?
-Continuous analgesia
-no dural puncture (no PDPH)
-Catheter in place can be used if converting to c section
76
What may the use of air for loss of resistance lead to?
Risk of patchy block and pneumocephalus with LOR with air
77
What are the signs of intravascular placement of epidural catheter when administering test dose?
Epinephrine if epidural is intravascular:
-↑HR by 20 bpm within 1 min
**Time test dose so it isn't occurring at same time as contraction (which will ↑ HR as well)**
78
What are the advantages of a CSE (combined spinal epidural)?
79
What are the disadvantages of Dural Puncture Epidural?
Increased risk of PDPH
Increased risk of postpartum neuraxial infection
80
What is the primary indication for single shot intrathecal injection?
Based on the limited duration of action primary indication is c section
-usually not suitable for labor analgesia
81
What are the disadvantages of single shot spinal/intrathecal?
82
What are the advantages of a continuous spinal?
83
In what scenario is lidocaine used for labor pain?
2% lidocaine is often used for "dose up" of an epidural during pushing
84
What are the safety features of continuous epidural infusion pumps?
Designated and dedicated infusion pump
-epidural tubing labeled and color coded
-no injection ports
-less risk of bacterial contamination
85
What are the disadvantages of Epidural PCEA?
86
What are the pros and cons of background infusions via PCEA pump?
87
Prior to introduction of PCEA infusions, periodic bolus dosing was prominent. Why is bolus dosing as primary treatment less effective?
-increased instances of regression of analgesia
-Decreased provider/mother satisfaction
-Increased provider workload
88
Bolus epidural dosing of 8-12 mL (with or without opioids) can lead to what?
-Dense motor blockade
-higher risk of hemodynamic instability
↳ ↓uterine/placental/fetal perfusion
89
How does the initial bolus with a continuous spinal differ from the CSE bolus?
They are the same
-initial bolus for CSE and Continuous spinal are the same
90
What are the continuous spinal infusion doses of bupivacaine and fentanyl? What is continuous spinal infusion dose of ropivacaine and fentanyl?
91
What interventions are utilized when a patient with epidural catheter complains of pain?
Intervention should be based on sensory level and progress of labor
92
What factors weigh in the decision to bolus epidural with pump vs off pump?
-if early in labor bolus with pump
-dense bolus is suitable if close to delivery
**off pump, dense bolus may be the expectation with any subsequent breakthrough pain if given early in labor**
93
What interventions are utilized when a patient who received a single shot spinal complains of pain?
Redo spinal
-not recommended d/t risk of PDPH
Place epidural and dose per initial CLE guidelines
94
What interventions are utilized when a patient with continuous spinal catheter complains of pain?
Assess location of intrathecal catheter
Use spinal/intrathecal dosing guidelines
95
What are the underlying causes of maternal HoTN secondary to neuraxial anesthesia?
-sympathetic blockade
-peripheral vasodilation
-increased venous capacitance
-decreased venous return
96
What is a viable treatment for refractory HoTN that is not responsive to treatment or that requires repeated vasopressor doses?
25-50 mg IM ephedrine
-allows steady dose
97
What are some epidural considerations for patients with HoTN?
-If just given bolus, can delay turning pump back on
-If pump at high rate; may need to turn down rate or turn pump off
98
What are some PDPH prevention techniques?
99
What are some treatment options for PDPH?
100
What is the likely intervention during a c section if the spinal is too low?
Patient will likely have inadequate pain control
-likely requires general anesthesia
101
Why may delayed gastric emptying occur after neuraxial anesthesia?
Opioid use with neuraxial anesthesia
102
Why may shivering be prominent in the laboring mother?
Shivering may be r/t hormones during labor
