OB exam one

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nikistivers
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284375
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OB exam one
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2014-09-29 23:03:22
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obstetrical anesthesia
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OB considerations for anesthetic choice
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  1. Airway Parameter Changes

    Diaphragm excursion
    Chest wall excursion
    Pulmonary resistance
    FEV1, FEV1/FVC, Flow volume loop, closing capacity
    • Increased
    • Decreased
    • Decreased by 50%
    • No change
  2. Does FRC increase or decrease?
    FRC decreases starting about the 5th month b/c relaxed diaphragm. The FRC is decreased by as much as 70% in the supine position when compared to upright in the pregnant patient.
  3. Describe the shifting of the heart during pregnancy
    The heart shifts anteriorly and to the left.

    Apical impulse moves cephalad to 4th intercostal space and laterally to the MCL

    Grade 1-2 murmur normal

    Cardiac hypertrophy is normal
  4. What is the total blood volume of a patriurient patient?
    90 ml/kg
  5. Cardiac output increases by ____ during the latent phase
    15%
  6. CO increases by ____ during the active phase
    30%
  7. CO increases by _______ during the expulsive stage of labor
    45%
  8. What lab values are seen in maternal anemia?
    • HCT < 33
    • HgB < 11

    A high Hgb (> 14) may indicate a low-volume state
  9. Describe the anticipated normal BP in pregnant women
    BP normally not increased even though CO is, due to decreased SVR and PVR and increased aortic compliance. The decreased SVR is partially due to the low resistance uterine vascular bed
  10. What can the venodilation seen in pregnancy affect in terms of regional pain management?
    increase incidence of accidental epidural vein puncture
  11. How much blood loss can a healthy patruient endure?
    Up to 1500 ml
  12. Name three events that may cause a low volume state
    • Preeclampsia
    • hypertension
    • inappropriate diuretic use
  13. What should we strive to maintain the systolic BP at?
    above 90mmHg
  14. Symptoms of aortocaval compression (6)
    • 1. hypotension
    • 2. pallor
    • 3. sweating
    • 4. nausea
    • 5. vomiting
    • 6. changes in mentation
    • Occurs when in supine position
  15. Treatment of aortocaval compression
    • FIRST: left uterine displacement
    • Then, fluids, oxygen, ephedrine.
  16. What position should you avoid if aortocaval compression in suspected?
    Trendelenburg
  17. Why could neosynephrine be a good choice for use in a pregnant hypotensive episode?
    Neo is a direct alpha agonist, and causes less fetal acidosis
  18. Hypotension following spinal anesthesia for C-section is a result of
    • sympathetic blockade
    • which leads to decreased SVR, VR, and CO
  19. Why does ephedrine have an increased incidence of fetal acidosis?
    It crosses the placenta
  20. When should phenylephrine be avoided?
    Maternal bradycardia because of the reflexive bradycardia it can cause
  21. Side effects of oxytocin
    • Cardiovascular: hypotension, tachycardia, arrhythmias, MI, coronary vasoconstriction
    • N/V
    • Flushing
    • Water retention
    • Hyponatremia
    • Seizures and coma
  22. Describe the etiology of oxytocin
    • Synthesized in hypothalamus, stored in the posterior pituitary
    • Oxytocin receptors on: uterus, ovary, breast, kidney, CNS, endothelial cells, heart.
  23. Onset and half-life of pitocin
    • onset: 1-2 minutes
    • half life: 3-10 minutes
  24. How is thrombocytopenia during pregnancy defined?
    Platelet count < 150,000
  25. At what platelet count should a provider not preform a spinal or epidural anesthetic?
    Less than 75,000
  26. In the thrombocytopenic patient, what is the preferred method of regional anesthesia and why?
    Spinal, because the smaller needle presents less risk of bleeding.
  27. Name 2 absolute contraindications for neuraxial block
    • Clinical signs of bleeding
    • progressively decreasing platelet counts
  28. How does estrogen affect the RAA system?
    Estrogen enhances renin production which increases blood volume in the end of the cycle.
  29. Albumin levels fall from __ in the 1st trimester to ____ at term
    4.5-3.9 g/dL

    3.3 g/dL
  30. Plasma cholinesterase falls by --- % at term
    25%.

    This is significant when considering sux. as the NMB for RSI  (longer duration)
  31. Which clotting factors increase in pregnancy?
    1, 7,8,9,10, 12
  32. Which clotting factors decrease in pregnancy?
    11, 13, PT, PTT, antithrombin 3, PLT count
  33. Which clotting factors remain unchanged during pregnancy?
    Factors 2 & 5
  34. Is the parturient hypercoagulable or hypocoagulable?
    hypercoagulable
  35. Hugh's syndrome is AKA and is what?
    • Antiphospholipid syndrome
    • Prothrombotic disorder resulting in venous and arterial thrombosis

    Causes platelet adhesion

    Lupus anticoagulant and anticardiolipin antibodies present
  36. What is the apparent mechanism of mortality for fetus's in antiphospholipid syndrome?
    Placental infarction
  37. Mendelson's syndrome
    pH < 2.5, GRV > 30ml.

    Increased progesterone reduces tone of GE sphincter, gravid uterus changes angle of GE junction

    This syndrome is a chemical pneumonitis caused by aspiration during anesthesia, especially during pregnancy
  38. At what point is a parturient considered a full stomach?
    12 weeks!
  39. What can be expected with BUN and CRT levels?
    Decrease
  40. Compression of the ureters by the uterus may result in
    urinary stasis= frequent UTIs
  41. What causes insulin resistance seen in pregnancy?
    hormones secreted by the placenta, mainly placental lactogen
  42. How should you adjust the MAC for pregnant patients?
    Decrease by up to 40%
  43. Indications for C-section:
    • failure to progress,
    • non-reassuring fetal status,
    • cephalopelvic disproportion,
    • malpresentation,
    • prematurity,
    • previous uterine surgery
  44. Hyperbaric LAs sink or rise in the spinal column?
    Sink. The addition of dextrose accomplishes this
  45. Which LA is most commonly used for spinal anesthesia in the parturient patient?
    bupivacaine
  46. A ___  MAC will result in vasodilaton that causes increased blood loss during c-section
    0.6 %
  47. Epidural LAs
    • 2-cholorprocaine 3%
    • lidocaine 2%
    • bupivacaine 0.5%
  48. How are nitroglycerin and terbutaline used in L&D?
    relax the uterine muscles to allow for external cephalic version
  49. Name 4 factors that complicate post-op recovery and decrease maternal satisfaction:
    • pain
    • pruritus
    • N/V
    • post-op shivering
  50. What vessel carries oxygenated blood back to the fetus from the placenta?
    Umbilical vein

    Is the only fetal vessel that carries fully oxygenated blood at a sat of 80%. After mixing with fetal shunts, the delivered blood has a sat of 67%
  51. How many arteries and veins are in the umbilical cord?
    2 arteries and 1 vein. Arteries carry oxygen poor blood back to the placenta, and the vein carries oxygen rich blood to the fetus from the placenta.
  52. Ductus venosus
    attachment point for umbilical vein to the fetal inferior vena cava
  53. Foramen ovale
    shunt opening between the right and left atrium
  54. septum primum
    fetal septum between right and left atrium. Is a valve that prevents blood from moving in reverse direction (left to right)
  55. With first breath, the _____ _____ and ________ ______ close.
    foramen ovale and ductus arteriosus
  56. Factors which optimize fetal oxygenation:
    • 1. uniform perfusion of the placenta
    • 2. production of a fetal Hgb with a greater oxygen affinity than maternal Hgb.
    • 3. High fetal cardiac activity
    • 4. increased fetal tissue perfusion
  57. Three microscopic tissue layers found in placental membrane:
    • 1. Fetal trophoblasts
    • (cytotrophoblast, syncytiotrophoblast)
    • 2. Fetal connective tissue
    • 3. endothelium of the fetal capillaries
  58. Placental vasculature normally exists in a _________ state.
    Vasodilated
  59. Uterine blood flow equation
  60. Uterine blood flow is 10% of maternal cardiac output at term, which is approximately:
    700ml/min
  61. Uterine blood flow is proportional to the mean perfusion pressure
    it is not autoregulated
  62. Factors that decrease UBF:


    • systemic hypotension
    • increased uterine venous pressure
    •     vena cava compression
    •     uterine contractions
    •     valsava maneuver with pushing
    •    drug induced uterine hypotonus
    • increased uterine vascular resistance
    •    vasopressin increases uvr
  63. Name the maternal arteries that supply the placenta
    Uterine

    • Ovarian
    • Arcuate
    • Radial

    • Basal
    • Spiral
  64. Two layers of the placenta
    myometrium and endometrium

    basal and spiral arteries supply the endometrium in the basal plate
  65. Where does exchange take place with fetal and maternal blood?
    intervillous space in the basal plate
  66. Fick principle relies on 5 factors:
    • Molecular weight
    • Solubility
    • Concentration gradient
    • Surface area
    • Membrane thickness
  67. What is the most important factor that affects diffusion?
    concentration gradient
  68. What two substances were identified as those who utilize facilitated diffusion for transport?
    lactic acid and glucose
  69. Which crosses the placenta more easily:
    Drugs that bind to albumin or a-alpha glycoprotein?
    Albumin, b/c a-alpha glycoprotein binds drugs more tightly
  70. What is transported via active transport?
    • Amino acids, large ions, vitamins.
    • Uses ATP, is fast
  71. How are mother's antibodies transferred to the fetus?
    Pinocytosis

    IgG
  72. What are the 5 mechanisms of placental exchange?
    • 1. diffusion
    • 2. bulk flow (facilitated diffusion)
    • 3. active transport
    • 4. pinocytosis
    • 5. breaks
  73. what causes a right shift in the oxyhemoglobin curve?
    acidosis, hyperthermia, increased 2,3 DPG
  74. what causes a left shift in the oxyhemoglobin dissociation curve?
    alkalosis, hypothermia, decreased 2,3 DPG, carbon monoxide
  75. IV epidural test dose can decrease uterine blood flow by
    40% during the 3 minutes of duration
  76. Normally, the fetus's oxyhemoglobin curve is shifted to the ___ of mothers'
    left
  77. The Hgb of fetal blood is about
    15 g/100ml blood

    mothers' is about 12
  78. when the curve is ----- shifted, Hgb binds more tightly
    left shifted
  79. Even though the fetus is more acidotic to than the mother, the Hgb curve is shifted to the left because
    increased Hgb affinity for oxygen
  80. How do inhalational agents affect the uterus?
    Potent uterine relaxant properties

    effects seen in dose dependent manner
  81. Is warfarin OK for pregnant patients?
    • No.
    • It crosses the placenta and is associated with fetal demise and congenital defects.

    Heparin and lovenox are OK to give
  82. What do local anesthetics do to uterine blood flow?
    exert a vasoconstrictor property. Normal concentrations used should be OK. Bupivicaine exerts a greater effect than cholorprocaine or lidocaine
  83. Which LA is safe from fetal trapping and why?
    Cholroprocaine. Because it is metabolized so quickly there is no opportunity for the drug to accumulate in significant amounts.
  84. Name some anesthetic drugs that cross the placenta
    • Atropine
    • Scopalamine
    • Beta agonists
    • nitroprusside
    • nitroglycerine
    • benzodiazepines
    • induction agents
    • inhalational agents
    • local anesthetics
    • opioids
    • ephedrine
  85. Name some anesthetic drugs that do not cross the placenta
    • robinol
    • heparin
    • lovenox
    • NMBs (DMBs in normal doses not > 300 mg)
  86. oligohydramnios
    too little amniotic fluid
  87. Fetal hydantoin syndrome
    • craniofacial abnormalities
    • caused by Dilantin use in pregnancy
  88. Ace inhibitors during pregnancy
    fetal renal dysplasia and oligohydramnios
  89. benzodiazepines birth defects
    • cleft lip
    • cleft palate
  90. antidepressants birth defects
    Prozac the only one associated with defects

    • exposure in 3rd trimester= greater incidence of preterm delivery
    • lower birth weight
  91. Coumadin birth defects
    ichthyosiform erytheroderma

    x-linked chrondrodysplasia punctata (CDPX)
  92. which steroid is preferred for maternal illness?
    prednisone
  93. which steroid is preferred to speed fetal lung development?
    betamethasone and dexamethasone
  94. Which antibiotics are safe for partriurients?
    PCN, cephalosporin, erythromycin

    Should try and avoid use, but these are preferred if must be used.

    sulfonamides in 3rd trimester increase the risk of hyperbilirubiemia
  95. effacement
    thinning of the cervix
  96. tocolysis
    production of relaxation by pharmacologic agent
  97. uterine contractions are monitored with
    tocodynamometer and intrauterine pressure catheter
  98. Station
    relation of the baby in relation to the pelvis

    • positive station= below the pelvis
    • negative station= above the pelvis
  99. First stage of labor
    onset of labor until dilation complete
  100. Latent phase
    during stage one

    before active labor, starts a few weeks before birth
  101. Active labor
    during stage one

    pain initially at 1 T11-12, then progresses to T 10-12 and L1
  102. second stage of labor
    from complete cervical dilation until delivery of neonate

    • onset of perineal pain is the signal of fetal descent
    • involves T10-S4 dermatomes
  103. Marcaine labor epidural concentration

    C-section epidural concentration
    0.125% or 0.0625%


    0.25% to 0.5% 


    Spinal 0.75% (7.5 mg in 2 ml)
  104. Three P's of labor and delivery
    powers (contractions)

    Passageway (bony pelvis and soft tissues)

    Passenger (fetus)
  105. nullipara prolonged second stage of labor
    > 2 hours without regional

    > 3 hours with regional
  106. multipara prolonged second stage of labor
    > 1 hour without regional

    > 2 hours with regional
  107. 3rd stage of labor
    from birth of the baby to the delivery of the placenta
  108. 4th stage of labor
    the hour after the delivery of the placenta. Most common time for uterine atony and uncontrolled bleeding.


    Boggy uterus requires fundal massage
  109. Test dose for epidural
    3-5 ml 1.5% lidocaine (45-75mg) with 1:200,000 epi (15-25 mg)
  110. Lidocaine spinal dosage limit
    • 75mg
    • concentration not to exceed 2%
  111. presentation
    the portion of the fetus felt thru the cervix on vaginal examination
  112. The best presentation is
    Left occiput anterior
  113. breech presentation
    Frank - 60% of time

    complete- 10% of time

    incomplete- 30% of time
  114. Risks of breech delivery
    • cervical laceration
    • perineal injury
    • shock from hemorrhage
    • retained placenta
    • infection

    • fetal intracranial bleed
    • asphyxia
  115. turtle sign
    retraction of the head back toward the vagina at delivery
  116. hemabate
    dose: 0.25mg IM q 15-90 minutes to a max of 2 mg

    Side effects: tachycardia, N/V, diarrhea
  117.  methergine
    dose: 0.2 mg IM single dose

    • Side effects: severe maternal htn
    • severe and prolonged uterine contractions
  118. pitocin
    • Dose: 10-40 units to 1 liter bag LR
    • Half life 3-5 minutes

    Side effects: hypotension, tachycardia, arrhythmias, MI, coronary vasoconstriction, N/V, Flushing, water retention, hyponatremia, seizures and coma

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