#209 Obstetric Analgesia and Anesthesia

Question 1

Where do women feel first stage of labor pain?

Answer 1

Diffuse. Lower abdominal pain is nearly universal, significant % will experience lower back pain. May be referred to iliac crests, buttocks, or thighs.

Question 2

As fetus descends in the first stage or second stage of labor, distention of the vagina, pelvic floor, and perineum elicit stimuli through what nerve(s)?

Answer 2

Pudendal nerve and the anterior primary divisions of sacral nerves S2 through S4

Question 3

Which opioid used for labor analgesia has the shortest duration of action?

Answer 3

Remifentanil, 3-4 minutes

Question 4

Which opioid used for labor analgesia has the most rapid onset of action?

Answer 4

Remifentanil, 20-90 seconds

next is nalbuphine 2-3min or fentanyl 2-4 min

Question 5

Which opioid used for labor analgesia has the longest duration?

Answer 5

Butorphanol 4-6hrs

Question 6

In general, how is the pain relief with parenteral opioids for labor analgesia?

Answer 6

Some pain relief, but poor, and associated with significant adverse events, mostly nausea, vomiting, drowsiness

Question 7

True or false, opioids do not cross the placenta

Answer 7

False

Question 8

How does opioid use affect fetus/neonate?

Answer 8

Loss of variability in FHR, reduction in FHR baseline, neonatal respiratory depression, or neurobehavioral changes

Question 9

True or false, opioid drug elimination takes the same time in newborns as adults?

Answer 9

False, longer in newborns, particularly in administered near the time of delivery

Question 10

Why is meperidine generally not recommended for peripartum analgesia?

Answer 10

Active metabolite (normeperidine) has a prolonged half life in adults and half life up to 72hrs in neonate; the effect cannot be antagonized by naloxone

Question 11

What opioids during labor are associated with less respiratory depression (compared to other opioids)?

Answer 11

Mixed agonist-antagonists such as nalbuphine and butorphanol. Remifentanil due to easy titration.

Question 12

What is a common risk of remifentanil PCA for labor analgesia?

Answer 12

Maternal apneic episodes (occur in 26% of women with PCA). Respiratory arrest has occurred.

Question 13

What % of women in the US having a singleton birth in the US select epidural or spinal analgesia?

Answer 13

More then 60%

Question 14

What level of education is associated with higher epidural use during labor? Race? Early or late presentation to prenatal care?

Answer 14

Higher education levels, white race, early presentation for prenatal care

Question 15

Does neuraxial analgesia increase the cesarean delivery rate?

Answer 15

No

Question 16

What medication(s) is placed through an epidural catheter?

Answer 16

Mix of local anesthetic and opioid medication; plus or minus epinephrine; plus or minus bicarb

Question 17

What effect does a local anesthetic have in epidural space?

Answer 17

Motor blockade, labor pain relief

Question 18

What are the commonly used local anesthetics for epidural anesthesia?

Answer 18

Bupivacaine and ropivacaine

Question 19

What opioids are common used for epidural anesthesia?

Answer 19

fentanyl and sufentanil

Question 20

What does addition of epinephrine to epidural block do?

Answer 20

prolong duration, increase reliability and intensity of block.

Question 21

What does the addition of sodium bicarb to epidural block do?

Answer 21

Speed up onset of epidural blockade, intensify the effect, or both, especially in sacral dermatomes

Question 22

What are methods of maintaining epidural anesthesia?

Answer 22

Intermittent boluses, continuous infusion or continuous infusion with patient-administered boluses

Question 23

How does intermittent bolus technique for epidural compare to continuous infusion?

Answer 23

No difference in total duration of labor. Significantly shorter second stage, less total anesthetic drug, higher maternal satisfaction

Question 24

Is epidural or opioids better for controlling labor pains?

Answer 24

Epidural

Question 25

What medication(s) is put into spinal block?

Answer 25

Mix of local anesthetic and opioid

Question 26

What anesthetics are used for spinal block?

Answer 26

Lidocaine, bupivacaines, ropivacaine

Question 27

What opioid(s) is used for spinal block?

Answer 27

Fentanyl, sufentanil, or morphine

Question 28

What is the concern about continuous spinal analgesia for labor?

Answer 28

Concerns about postdural puncture headache. | Caution with labeling, use, dosage, and sterility on intrathecal catheter

Question 29

What is a downside of combined spinal-epidural anesthesia?

Answer 29

Epidural catheter placement cannot truly be verified until the spinal component has "worn-off"

Question 30

How does intrathecal opioids lead to fetal bradycardia?

Answer 30

Independent of maternal hypotension. Hypothesized that fast pain relief, lowers maternal plasma epinephrine and beta-endophines, leaving oxytocin and norepinephrine unopposed, which leads to uterine hypertonus and reduction in ureteroplacental blood flow

Question 31

What is the landmark for pudendal block?

Answer 31

Ischial spine

Question 32

When is a pudendal block useful?

Answer 32

Second stage of labor or after delivery to facilitate repair of perineal lacerations

Question 33

What is maximum recommended bupivacaine dosing w/ and w/o epi?

Answer 33

3mg/kg for both

Question 34

What is the maximum recommended lidocaine w/ and w/o epi?

Answer 34

7mg/kg w/. | 5mg/kg w/o.

Question 35

What is recommended maximum dose of ropivacaine w/ and w/o epi?

Answer 35

2mg/kg for both

Question 36

What is the recommended maximum dose of 2-chloroprocaine w/ and w/o epi?

Answer 36

14mg/kg w/. | 11 mg/kg w/o.

Question 37

What are possible symptoms of local anesthetic toxicity (eg from injecting into blood stream)?

Answer 37

Neurologic symptoms (eg, seizures, coma) or cardiac symptoms (eg, arrhythmias, myocardial depression)

Question 38

Do CNS or cardiac manifestations of local anesthetic toxicity typically manifest first?

Answer 38

CNS symptoms

Question 39

What is the interaction between hypoxemia and acidosis with local anesthetic systemic toxicity? What should you do?

Answer 39

Hypoxemia and acidosis potentiate local anesthetic systemic toxicity. Treat with IV lipid emulsion

Question 40

What logistics need to be in place to give nitrous oxide during labor?

Answer 40

Need supply with apparatus that must use a demand valve. Must have scavenging equipment.

Question 41

How does analgesia from nitrous oxide compare to epidural?

Answer 41

Not as good as epidural in regards to pain scores

Question 42

What are maternal adverse effects of nitrous oxide use?

Answer 42

Nausea, vomiting, dizziness, and drowsiness

Question 43

When nitrous oxide is used for labor analgesia, is it cleared quickly or slowly from the neonate?

Answer 43

Eliminated rapidly by the neonate after he or she begins to breathe

Question 44

Can nitrous oxide be used safely with other forms of analgesia for labor pain?

Answer 44

Yes

Question 45

What is the role of general anesthesia in labor and delivery?

Answer 45

Typically limited to emergency cesarean deliveries or scenarios in which neuraxial anesthesia cannot be performed or has already failed

Question 46

Do anesthestic needs change before and after delivery of the newborn during general anesthesia?

Answer 46

Yes

Question 47

What anesthetics used for general anesthesia can cause decreased uterine tone?

Answer 47

Inhaled volatile agents, eg sevoflurane or isoflurane. Typically these will need to be maintained with low concentrations.

Question 48

What is the rate of failed intubations among pregnant patients compared to nonpregnant surgical patients?

Answer 48

Pregnant: 1 in 224 to 1 in 390 Nonpregnant: 1 in 2230

Question 49

What is the failure rate of neuraxial anesthesia for cesarean delivery?

Answer 49

1.7%

Question 50

The Serious Complication Repository Project was created to estimate the frequency of severe adverse outcomes associated with obstetric anesthesia. How many out of 300,000 recorded cases had events?

Answer 50

157. 2 cardiac arrests, 2 myocardial infarctions, 4 epidural abscess or meningitis (<1:60,000), 1 epidural hematoma (1:250,000), 10 failued intubations, 58 high neuraxial blocks. 7 neurologic injuries. 16 respiratory arrests.

Question 51

Are epidural or spinal blocks at higher risk for high neuraxial blocks?

Answer 51

Nearly equally distributed

Question 52

What puts a patient at risk for a high neuraxial block?

Answer 52

Unrecognized spinal catheter. Attributed to 24% of cases high neuraxial blocks

Question 53

What is the rate of postdural puncture headache after spinal or combined spinal-epidural anesthesia?

Answer 53

0.7%

Question 54

What is the standard therapeutic intervention for a postdural puncture headache?

Answer 54

Epidural blood patch

Question 55

Are epidural or intrathecal opioids more likely to lead to pruritis?

Answer 55

Intrathecal

Question 56

What are minor maternal adverse effects associated with neuraxial blocks?

Answer 56

Maternal hypotension, pruritis, nausea/vomiting. Temperature elevation or fever (epidural related), shivering, urinary retention, and reactivation of oral herpes, respiratory distress.

Question 57

What are treatment options for opioid-induced pruritis (centrally induced)?

Answer 57

Small doses of naloxone or nalbuphine (but these can reverse some of the analgesic effect). Antihistamines, but these have little to no effect on centrally-induced pruritis, but may increase drowsiness, leading to improvement in symptoms

Question 58

What % of women will develop hypotension from low-dose neuraxial labor analgesia?

Answer 58

About 10%

Question 59

What can be done to help prevent maternal hypotension with neuraxial anesthesia?

Answer 59

Preloading or coloading with crystalloid or by administering small doses of vasopressors (ephedrine or phenylephrine)

Question 60

Is the risk of spinal or epidural hematoma higher with spinal or epidural?

Answer 60

Epidural

Question 61

What is the risk of spinal-epidural hematoma in patient with platelets between 70k-100k?

Answer 61

0-0.6%

Question 62

Can epidural/spinal anesthesia be used in patients with platelets <70k?

Answer 62

It may be acceptable in some circumstances. There is insufficient data to assess risk in patients with platelets <70k

Question 63

What is the risk of serious morbidity from general anesthesia during a cesarean delivery?

Answer 63

6.5%

Question 64

Is use of low-dose aspirin a contraindication for neuraxial techniques?

Answer 64

No

Question 65

Is the presence of a space-occupying brain lesion a contraindication to epidural anesthesia?

Answer 65

Not necessarily. If it does not result in increased ICP (no mass effect, hydrocephalus), risk of herniation is minimal and epidural anesthesia can be considered

Question 66

What % of women will experience an increase in maternal temperature (>99.5oF) with neuraxial analgesia?

Answer 66

30%

Question 67

What makes a woman more likely to have an increased temperature with epidural anesthesia?

Answer 67

Nulliparity. Prolonged use of epidural.

Question 68

Does giving prophylactic antibiotics prior to epidural placement reduce the risk of developing fever?

Answer 68

No

Question 69

How does intrathecal opioids vs systemic opioids affect the length of the first stage of labor?

Answer 69

90 minutes shorter in women with intrathecal opioids

Question 70

How does epidural, compared to no epidural, affect length of second stage of labor?

Answer 70

Epidural prolongs the second stage of labor by a mean difference of 7.66 minutes without negative effects to fetus and neonate

Question 71

Does initiation of epidural anesthesia at any stage of labor increase the risk of cesarean delivery?

Answer 71

No

Question 72

Does HELLP syndrome affect platelet number or quality?

Answer 72

Both. Consumption of platelets coupled with impaired platelet function

Question 73

Can women breast feed after general anesthesia?

Answer 73

Yes, as soon as they are awake, stable, and alert

Question 74

How does maternal opioid use affect infants?

Answer 74

Can cause neonatal depression or drowsiness and can interfere with suckling

Question 75

What is the dermatone level goal for a cesarean section?

Answer 75

T4

Question 76

What anesthesia options are available if a woman needs an emergent cesarean section?

Answer 76

If epidural in place can titrate this in ~10mins. Place spinal (~8 min). General anesthesia (~2 min) Local anesthetic

Question 77

If patient is feeling pain during cesarean section, what can you do as a surgeon to improve tolerability?

Answer 77

Gentle tissue handling. | Do not exteriorize the uterus (requires higher sensory level than in situ repair)

Question 78

What are the pros and cons of preservative-free morphine used in spinal or epidural anesthesia for cesarean section?

Answer 78

Provides 12-24hrs of post op analgesia. | Risks of pruritus, nausea, respiratory depression

Question 79

Does wound infiltration with local anesthetic at the time of cesarean delivery decrease post op opioid consumption?

Answer 79

Yes, during first 12-24hrs

Question 80

How does transversus abdominis plane blocks affect post op opioid use after cesarean section?

Answer 80

Decrease post op morphine requirements by more than 70%. However, do not improve pain relief when intrathecal morphine is given.

Question 81

What particular opioid is not recommended for breastfeeding mothers?

Answer 81

Codeine

Question 82

Oxycodone greater than how many miligrams per day is not recommended for breastfeeding women?

Answer 82

30mg/day

Question 83

How long after SQH 5000u BID injection can neuraxial catheter be placed or removed?

Answer 83

More than 4-6 hours since last dose

Question 84

How long after intermediate-dose unfractionated heparin (7.5-10k u) can neuraxial catheter be placed or removed?

Answer 84

More than 12 hours

Question 85

How long after high-dose unfractionated heparin (>20k u/day) can neuraxial catheter be placed or removed?

Answer 85

More than 24 hours with aptt in normal range or anti-factor Xa level undetectable

Question 86

After how many days of heparin use, should a platelet count be checked prior to placement or removal of neuraxial catheter to check for possible heparin-induced thrombocytopenia?

Answer 86

If taking for more than 4 days

Question 87

How soon after neuraxial catheter removal can you resume unfractionated heparin?

Answer 87

Resumed more than 1 hour after catheter removal

Question 88

How long after prophylactic LMW heparin administration should you wait for neuraxial needle or catheter placement or removal?

Answer 88

Delay by at least 12 hours after last dose

Question 89

How long after therapeutic LMW heparin administration should you wait for neuraxial needle or catheter placement or removal?

Answer 89

24 hour delay

Question 90

How long after neuraxial catheter removal can you resume thrombopropylaxis with LMW heparin?

Answer 90

Resume more than 4 hours after catheter removal

Question 91

Does neuraxial analgesia increase the cesarean delivery rate?

Answer 91

No