209 - Obstetric Anesthesia and Analgesia

Question 1

Relationship between obstetric analgesia and cesarean?

Answer 1

None for any method!

Question 2

Parenteral opioid options for obstetric analgesia and their dosage/onset/duration/half life

Answer 2

Question 3

Which opioid is not used in obstatrics and why?

Answer 3

meperidine, because its active metabolite, normeperidine, has a prolonged half-life in adults and a half-life of up to 72 hours in the neonate; the normeperidine effect cannot be antagonized by naloxone

Question 4

Effects of opioid on fetus/neonate

Answer 4

• loss of variability in the fetal heart rate
• reduction in the FHR baseline
• neonatal respiratory depression
• neurobehavioral changes

Question 5

Which of the 5 obstetric opiates should not be used in patients taking chronic opiates and why?

Answer 5

Butorphenol and nalbuphine becuase they are mixed agonist–antagonists so they can perpetuate withdrawal. Because of this they have less respiratory depression

Question 6

Which opiate has been shown to be the most effective

(though still less than epidural), and what are specific risks and benefits?

Answer 6

Remifentanyl PCA

Risks: respiratory depression

Beinefts: rapid onset/elimination, no active mtabolites

Question 7

Overall rate of epidural use?

Answer 7

60%

Question 8

Factors associated with epidural use?

Answer 8

Higher education, white race, early entry to prenatal care

Question 9

What are the commong

Question 10

What are benefits of intermittent bolus epidural as opposed to continuous infusion?

Answer 10

1) shorter second stage (no difference in total labor duration)
2) slightly less total anesthetic dosing
3) higher maternal satisfaction

Question 11

Contents of spinal?

Answer 11

lidocaine, bupivacaine, and ropivacaine.

Fentanyl, sufentanil, or morphine may be added to the mixture to improve intraoperative comfort, postoperative comfort, or both

Question 12

Continuous spinal anallgesia?

Answer 12

Not really used, risk of postdural puncture headache

Question 13

Combine spinal epidural: when should it be used? What risks are there and what is the mechanism?

Answer 13

For quick relief.

Increase risk of betal bradycardia - independent of materal hypotension, may be due to pain relief –> decreased plasma epinephrine and beta-endorphins –> unopposed oxytocin and norepinephrine –> uterine hypertonus and a reduction in uteroplacental blood flow

Question 14

which is better, single shot spinal vs. pudendal block for;

a) labor and delivery
b) episiotomy repair

Answer 14

a) labor and delivery: spinal
b) episiotomy repair: same

Question 15

Benefit of adding epinepherine to local anesthesia for repairs? who is it contraindicated in?

Answer 15

vasocontriction –> prolonged effect.

Cant use if cardiac disorders due to increase in HR and BP if intravascular

Question 16

Risks of local anesthesia?

Answer 16

1) allergy - to chloroprocaine and tetracaine, to perservative methylparaben, or to sulfites
2) toxicity: mouth tingling, then neurologic symptoms (eg, seizures, coma), then cardiac symptoms (eg, arrhythmias, myocardial depression). Hypoxemia and acidosis, which potentiate local anesthetic systemic toxicity, should be corrected quickly with intravenous lipid emulsion

Question 17

Benefits and AE of inhaled agents for labor pain

Answer 17

Nitrous oxide

Benefits: PCA, full mobility, no monitoring, quick termination, quickly expelled from neonate when they breathe, can be used in addition to other forms of analgesia

AE: nausea, vomiting, dizziness, and drowsiness, less effective than epidural

Question 18

Max dose of local anesthetics with an without epi for:

• bupivicaine
• lidocaine
• ropivicaine
• 2-chlorprocaine

Answer 18

Question 19

List of reasons to get anesthesiology consultation pre-natally

Answer 19

Question 20

What is risk of postdural puncture headache for CSE/spinal?

Answer 20

0.7%

Question 21

Why do you get pruritis after neuraxial blocks and how can you counteract it?

Answer 21

opioid binding to the μ-opioid receptor

Counteract with naloxone or nalbuphine but this may weaken analgesic effect. Can also use benadryl which doesn;t actually help the central-mediated pruritis but can make them sleepy

Question 22

AE of neuraxial anesthesia for mom

Answer 22

hypotension, nausea and vomiting (when opioids are used), temperature elevation or fever (epidural related), shivering, urinary retention, and reactivation of oral herpes

Question 23

What % of patient recieving epidural vs. CSE with have increased uterine tone?

What % of fetuses show FHR abnormalities following CSE?

Does this affect cesarean rate, APGAR scores, or neonatal acidemia?

Answer 23

What % of patient recieving epidural vs. CSE with have increased uterine tone? epidural 17%, CSE 42%

What % of fetuses show FHR abnormalities following CSE? 33% (1/3)

Does this affect cesarean rate, APGAR scores, or neonatal acidemia? (no)

Question 24

What is the rate of epidural hematoma for epidural vs. spinal?

Answer 24

epidural: 1/150’000

Spinal: <1/220’000

Probably increased by thromboprophylaxis

Question 25

what is the general concensus for lower limit of platelets for neuraxial anesthesia?

Alternatively, what is the rate of “serious morbidity” from general anesthesia in patients laboring –> cesarean?

Answer 25

Plt should be >70k, stable, with normal function, no anticoagulation, no other coagulopathy

6.5% serious morbidity for GA

Question 26

What is the cited risk of epiural hematoma for neurazial blockage if plt 70-100K?

Answer 26

0-0.6%

Question 27

Aspirin and neuraxial anesthesia?

Answer 27

no problem!

Question 28

What brain issue do you worry about hindbrain herniation with dural puncture?

Answer 28

Increased ICP

(you can have brain masses that dont have increased ICP so are not of concern)

Question 29

What is the rate of epidural fever, what are RF for it, why does it happen, is there an association with infection/inflammation?

Answer 29

30%

Increased likelihood with longer duration, nulliparous

Uncertain etiology

Only thing seen is increased placental inflammation

Question 30

Does epidural analgesia affect the progress of labor or the rates of operative or cesarean delivery?

Answer 30

Trial of neuraxial vs. systemic opioids: 90 minute shorter first stage if neuraxial

Trial of epidural vs. no epidural: 7.6 minute increase in second stage with no change in fetal/neonatal status

Cesarean: no increase

Operative: more if epidural, but not with data since 2005 (maybe due to less local anesthetics in modern epidurals)

Question 31

Effect of GA, IV opioids, neurxial anesthesia on breastfeeding

Answer 31

GA: 2% of moms blood stream concentration in breastmilk, ok and safe

IV opioids: drwosy baby, decreased suckling

Neuraxial: poor studies, probably no risks

Question 32

Anesthesia options for emergent cesarean?

Answer 32

If epidural: load with local anesthetic, ~10mins

If no epidural: Spinal (9 mins start to go) vs. GA (5 mins including 3min preoxygenation) vs. local lidocaine +/- IV sedation

Question 33

Additional uses for anesthetics after cesarean

Answer 33

1) wound infiltration with local anesthetic
2) ilioinguinal or iliohypogastric nerve block
3) transversus abdominis plane block
4) continuous irrigation of the wound with local anesthetic

Question 34

which opiate to avoid in breastfeeding?

Answer 34

codeine

Question 35

max recommended dose of oxycodone in breastfeeding women

Answer 35

30mg/d

Question 36

timing of low dose UFH (5000u BID) and neuraxial anesthesia?

intermediate dose UFH (7500-10000u BID)?

High dose UFH (>20000u)?

prophylactic LMWH?

Treatment dose LMWH?

Answer 36

Low UFH: place/remove: 4-6h after last dose, next dose after removal: 1h

Intermediate UFH: 12-24hrs

High dose UFH: 24hrs with normal aPTT and anti-Xa

PPx LMWH: 12hrs, next dose >4hrs after removal

Tx LMWH: 24hrs