209 - Obstetric Anesthesia and Analgesia Flashcards
Relationship between obstetric analgesia and cesarean?
None for any method!
Parenteral opioid options for obstetric analgesia and their dosage/onset/duration/half life
Which opioid is not used in obstatrics and why?
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
Effects of opioid on fetus/neonate
- loss of variability in the fetal heart rate
- reduction in the FHR baseline
- neonatal respiratory depression
- neurobehavioral changes
Which of the 5 obstetric opiates should not be used in patients taking chronic opiates and why?
Butorphenol and nalbuphine becuase they are mixed agonist–antagonists so they can perpetuate withdrawal. Because of this they have less respiratory depression
Which opiate has been shown to be the most effective
(though still less than epidural), and what are specific risks and benefits?
Remifentanyl PCA
Risks: respiratory depression
Beinefts: rapid onset/elimination, no active mtabolites
Overall rate of epidural use?
60%
Factors associated with epidural use?
Higher education, white race, early entry to prenatal care
What are the commong
What are benefits of intermittent bolus epidural as opposed to continuous infusion?
1) shorter second stage (no difference in total labor duration)
2) slightly less total anesthetic dosing
3) higher maternal satisfaction
Contents of spinal?
lidocaine, bupivacaine, and ropivacaine.
Fentanyl, sufentanil, or morphine may be added to the mixture to improve intraoperative comfort, postoperative comfort, or both
Continuous spinal anallgesia?
Not really used, risk of postdural puncture headache
Combine spinal epidural: when should it be used? What risks are there and what is the mechanism?
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
which is better, single shot spinal vs. pudendal block for;
a) labor and delivery
b) episiotomy repair
a) labor and delivery: spinal
b) episiotomy repair: same
Benefit of adding epinepherine to local anesthesia for repairs? who is it contraindicated in?
vasocontriction –> prolonged effect.
Cant use if cardiac disorders due to increase in HR and BP if intravascular
Risks of local anesthesia?
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
Benefits and AE of inhaled agents for labor pain
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
Max dose of local anesthetics with an without epi for:
- bupivicaine
- lidocaine
- ropivicaine
- 2-chlorprocaine
List of reasons to get anesthesiology consultation pre-natally
What is risk of postdural puncture headache for CSE/spinal?
0.7%
Why do you get pruritis after neuraxial blocks and how can you counteract it?
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
AE of neuraxial anesthesia for mom
hypotension, nausea and vomiting (when opioids are used), temperature elevation or fever (epidural related), shivering, urinary retention, and reactivation of oral herpes
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?
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)
What is the rate of epidural hematoma for epidural vs. spinal?
epidural: 1/150’000
Spinal: <1/220’000
Probably increased by thromboprophylaxis
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?
Plt should be >70k, stable, with normal function, no anticoagulation, no other coagulopathy
6.5% serious morbidity for GA
What is the cited risk of epiural hematoma for neurazial blockage if plt 70-100K?
0-0.6%
Aspirin and neuraxial anesthesia?
no problem!
What brain issue do you worry about hindbrain herniation with dural puncture?
Increased ICP
(you can have brain masses that dont have increased ICP so are not of concern)
What is the rate of epidural fever, what are RF for it, why does it happen, is there an association with infection/inflammation?
30%
Increased likelihood with longer duration, nulliparous
Uncertain etiology
Only thing seen is increased placental inflammation
Does epidural analgesia affect the progress of labor or the rates of operative or cesarean delivery?
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)
Effect of GA, IV opioids, neurxial anesthesia on breastfeeding
GA: 2% of moms blood stream concentration in breastmilk, ok and safe
IV opioids: drwosy baby, decreased suckling
Neuraxial: poor studies, probably no risks
Anesthesia options for emergent cesarean?
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
Additional uses for anesthetics after cesarean
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
which opiate to avoid in breastfeeding?
codeine
max recommended dose of oxycodone in breastfeeding women
30mg/d
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?
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
