Obstetric Flashcards

1
Q

MAC requirements for inhaled anesthetics (2)

A
  1. Reduce by 30-40% at peak

2. Returns to normal about 3 days after delivery

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2
Q

Proposed mechanism for reduce MAC requirements?

A

increased circulating endorphins; 10-20fold increase in progesterone late in pregnancy, have CNS depressant effects

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3
Q

3 examples of reduce in MAC requirements?

A
  1. Inspired dose of volatile agent to supplement neuro axial anesthesia for sedation, may cause loss of consciousness
    1. Increase sensitivity to benzodiazepines and barbiturates
    2. No change in Propofol or ketamine doses
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4
Q

Blood volume increase or decrease and how does it continue throughout pregnancy?

A

Increase: starts early, increases rapidly in 2nd trimester and slows in 3rd trimester

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5
Q

Does plasma volume or RBC volume increase and what can that cause?

A

Plasma volume; dilutional anemia (similar for some drugs)

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6
Q

At term what is a normal Hg?

A

11.6g/dL

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7
Q

CO and HR increase or decrease and how does it continue throughout pregnancy?

A

increase: increase at 10 wks, peaks at 30-50% increase at 32 wks

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8
Q

Increase CO and HR leads to what early and then eventually what?

A

early: SV

later: SV and HR

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9
Q

Is myocardial contractility changed during pregnancy?

A

NO

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10
Q

HR peaks at what bpm at term?

A

10-20 bpm

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11
Q

What 3 things decreased with pregnancy?

A

Systemic resistance, SBP, DBP

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12
Q

Dilutional anemia new “normal” values?

A

Hgb 9-11 g/dL (depends on iron supplementation)

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13
Q

What would be suggest if Hgb >13 g/dL?

A

hemoconcentration, need to look for cause (preeclampsia)

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14
Q

Platelet count and function?

A

No change in count to modest decline of ~10%

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15
Q

Pregnancy is what kind of coagulable state?

A

hypercoagulable (increase procoagulant factors, decrease fibrinolytic system and natura inhibitors of coagulation)

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16
Q

Why is pregnancy in hypercoagulable state?

A

minimize intrapartum blood loss

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17
Q

Hypercoagulable state may increase what risk during pregnancy and post parturm?

A

thromboembolism (6fold)

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18
Q

What does the fibrinolytic system get activated?

A

postpartum period

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19
Q

Hemoglobin has what kind of estimated change?

A

decrease 20%

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20
Q

Gastric emptying?

A

normal throughout gestation but slows with onset of painful contractions and parenteral opioids

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21
Q

What can increase gastric emptying?

A

clear liquids

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22
Q

When does gastric emptying return to normal?

A

18-24 hrs

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23
Q

Is gastric emptying impacted by Na channel blocking LA?

A

NO

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24
Q

Gastric secretions?

A

reduced (increased pH); but amount of secretions are unchanged

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25
Q

Lower esophageal sphincter (LES) tone?

A

reduces; increase risk of aspiration and regurgitation

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26
Q

What is LES barrier impacted by? (2)

A
  1. Progesterone adn estrogen relax the smooth muscles of LES
    1. Elevation/rotation of stomach by enlarging uterus
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27
Q

What 2 things can cause changes in liver function?

A

increased estrogen and progesterone

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28
Q

Hepatic BF?

A

BF and liver size remain unchanged despite increase CO

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29
Q

Splanchnic, portal and esophageal venous pressure?

A

increase

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30
Q

Serum albumin concentration?

A

reduce by 60% due to increase plasma volume; reduced total protein

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31
Q

Gamma globulin pregnancy effect?

A

no change to slight decrease

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32
Q

Fibrinogen pregnancy effect?

A

reduction 50%

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33
Q

Bilirubin pregnancy effect?

A

no change

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34
Q

ALP pregnancy effect?

A

increase 2-4 fold

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35
Q

GGTP pregnancy effect?

A

reduced

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36
Q

AST and ALT pregnancy effect?

A

none

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37
Q

TG and cholesterol pregnancy effect?

A

increased 2-3 fold

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38
Q

Hb pregnancy effect?

A

decrease 20%

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39
Q

Platelets pregnancy effect?

A

no change or decrease about 10%

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40
Q

Clotting factors (7, 8, 10, 12) pregnancy effect?

A

increase (30-250%)

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41
Q

Fibrinogen pregnancy effect?

A

increase

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42
Q

Protein S pregnancy effect?

A

decrease 40-50%

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43
Q

BV pregnancy effect?

A

increase 35%

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44
Q

Plasma volume pregnancy effect?

A

increase 55%

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45
Q

CO pregnancy effect?

A

increase 40-50%

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46
Q

SV pregnancy effect?

A

increase 25-30%

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47
Q

Pulse pressure pregnancy effect?

A

increase

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48
Q

HR pregnancy effect?

A

increase 15-20%

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49
Q

Systemic Resistance pregnancy effect?

A

decrease 15-20% (trimester specific)

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50
Q

SBP pregnancy effect?

A

decrease 5%

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51
Q

DBP pregnancy effect?

A

decrease 15%

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52
Q

Renal BF?

A

increase 75%

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53
Q

Renal afferent and efferent arterial resistance and when does it return to normal?

A

reduced; 6 months postpartum

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54
Q

GFR?

A

increase from 100-150 ml/min by 2nd trimester

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55
Q

BUN and sCr?

A

reduces; normal and slightly higher values may signal poor renal function

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56
Q

What causes gestational DM?

A

reduction in renal tubular reabsorption of glucose

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57
Q

Do you get proteinuria?

A

yes

58
Q

Thyroid gland?

A

englarges with increased vascularity

59
Q

T3 and T4?

A

increase by 50%

60
Q

TSH?

A

slight decline early then returns to normal

61
Q

Tissue sensitivity to insulin and why?

A

reduced due to placental hormone

62
Q

Fasting blood glucose?

A

lower

63
Q

Relaxin levels?

A

increase to prepare for delivery

64
Q

An agent that, under certain conditions of exposure, has the potential to cause abnormal fetal growth and development

A

Teratogen

65
Q

Capability of producing congenital abnormalities, major or minor malformations

A

Teratogenicity

66
Q

What can cause different outcomes resulting from drug exposure for teratogen?

A

Stage of pregnancy

67
Q

teratogen could destroy the embryo leading to a terminated pregnancy; likely unknown to the mother. Alternatively, exposure may cause no problems.

A

“All or nothing” effect

Week 1 & 2; blastogenesis

68
Q

Organ systems are developing during this stage; teratogenic exposures may result in organ system abnormalities (heart or neural tube defects)

A

Structural anomalies

18-60 days; organogenesis

69
Q

Exposure to teratogens may result in growth retardation, CNS abnormalities or extreme cases (death)

A

Remainder of the pregnancy

>60 days; growth and maturation

70
Q

Are there any drugs known to be safe for teratogens?

A

NO

71
Q

Where is the exchange for a number of substances (nutrients, gases, antibodies, and some meds)

A

Placenta

72
Q

What 4 drug properties influence placental transfer?

A
  1. Molecular wt (size)
  2. Protein binding (decrease albumin)
  3. Solubility (lipophilic drugs cross easily; opiates)
  4. Ionization (will not cross because ionized is acidic)
73
Q

When is elective surgery delayed?

A

2-6 weeks postpartum

74
Q

If cannot delay elective surgery, when is best time for it?

A

2nd trimester

75
Q

Why is induction and emergency form anesthesia more rapid? (2)

A
  1. Increased minute vent

2. Decreased functional residual capacity

76
Q

What is considered safe to use for non-obstetric surgery? (6)

A
Propofol (2mg/kg)
Ketamine (1-2 mg/kg)
Sux (1.5 mg/kg)
Epidural analgesic 
Opioids 
Acetaminophen
77
Q

What should be AVOIDED >32 wks gestation?

A

NSAIDs

78
Q

Do you need to change your dosage for sux?

A

No because Vd increased but systemic pseudocholinesterase activity decreased

79
Q

5 preterm labor management drugs?

A
CCB
B2 agonist 
NSAID
Antenatal corticosteroids 
Magnesium sulfate
80
Q

Is CCB or B2agonist superior?

A

CCB

81
Q

Mechanism of CCB?

A

Decrease Ca movement into smooth muscle cells through modulation of the duration of opening of the Ca channel

82
Q

Which CCB drug is most common?

A

Nifedipine

83
Q

Which CCB is not recommended?

A

Nicardipine

84
Q

Most common adverse effect of CCB?

A

Hypotension

85
Q

What can CCB lead to?

A

Refractory postpartum hemorrhage in setting uterine atony because oxytocin and prostaglandin agonist works through CCB mechanism to treat atony

86
Q

Mechanism of action for beta 2 agonists?

A

Increased cAMP lead to uterine smooth muscle relaxation by lowering intracellular Ca concentration. cAMP decreases activity of myosin light-chain kinase, which cause muscle contraction

87
Q

When is beta2 agonist most useful?

A

Uterine hypertonus

88
Q

What has a black box warning for concerns of maternal heart problems and death?

A

Beta 1 and 2 agonists

89
Q

B1 affect what and B2 affect what?

A

B1: HR
B2: DBP

90
Q

How long do you delay anesthesia after beta agonist given?

A

1 hr

91
Q

Prostaglandin inhibitors (NSAIDs) are effective at what?

A

Delaying delivery in setting of preterm labor

92
Q

Mechanism of action of prostaglandin inhibitors?

A

Inhibit COX1 and COX2 enzymes

93
Q

Ketorolac max dose?

A

120 mg/day

94
Q

Does nitroglycerin affect the fetus?

A

No

95
Q

IV dose of nitroglycerin?

A

50-100mcg

96
Q

Magnesium sulfate should be used as a caution when using for what?

A

Preeclampsia/eclampsia

97
Q

Uterotonic meds are used for what 5 cases?

A
  1. Uterine atony
  2. Postpartum hemorrhage
  3. Induction of labor
  4. Pregnancy termination
  5. Cervical ripening
98
Q

Oxytocin is natural hormone and called what?

A

Nonapeptide

99
Q

Pitocin is a synthetic hormone and called what?

A

Octapeptide

100
Q

Which uterotonic med is more selective for uterine receptors, minimizing renal anti diuretic hormone effects?

A

Pitocin; synthetic hormone; octapeptide

101
Q

Mechanism of action for oxytocin/pitocin?

A

Oxytocin acts on G protein receptors, activating Ca channels, increasing local prostaglandin production to induce uterine smooth muscle contraction

102
Q

How many oxytocin/pitocin for labor induction?

A

1-2 units/min

103
Q

How many oxytocin/pitocin is needed for uterine atony?

A

10-40 units diluted in a liter of isotonic fluid

104
Q

4 maternal adverse effects to oxytocin/Pitocin?

A
  1. Hypotension
  2. Fluid retention
  3. Tachysystole (>5 contractions in 10min averaged over 30min)
  4. Uterine rupture due to uterine hyperstimulation
105
Q

2 fetal adverse effects from oxytocin/pitocin?

A
  1. Hypoxia

2. Bradycardia due to hypertonic contractions

106
Q

A synthetic ergot alkaloid

A

Methylergonovine/methergine

107
Q

MOA for methergine?

A

Causes dose dependent increase in uterine contraction and tone. Mediated via alpha adrenergic receptors in uterus

108
Q

4 adverse effects for methergine?

A
  1. Peripheral vasoconstriction so increase BP
  2. Increased pulmonary artery pressure
  3. Coronary artery vasospasm
  4. Nausea and vomiting
109
Q

Dosing for methergine?

A

IM .2mg over 2-4 hrs (max .8)

110
Q

Who do you avoid methergine with?

A

HTN/preeclampsia; peripheral vascular disease and ischemic heart disease

111
Q

If pt gets HTN with methergine, how do you treat it?

A

Hydralazine and nitroglycerin

112
Q

Naturally occurring hormones, which enhance uterine contractility and cause vasoconstriction

A

Prostaglandins E2, F2a, E1

113
Q

Together with oxytocin essential for parturition

A

Endogenous hormones

114
Q

Dose dependent increase in uterine tone

A

Exogenous drug

115
Q

MOA of prostaglandins?

A

Increase myometrial Ca concentrations which lead to increased myosin light chain kinase activity and uterine contraction

116
Q

4 reasons prostaglandins are used:

A
  1. Uterine atony
  2. Induction of labor
  3. Cervical ripening
  4. Induce abortion
117
Q

Common dosage for prostaglandin (carboprost, hemabate)?

A

IM of .25 mg can repeat every 15min for total dose of 2mg

118
Q

When should carboprost; hemabate be avoided? (5)

A
  1. Hypersensitivity
  2. Asthma
  3. HTN
  4. Renal impairment
  5. Hepatic impairment
119
Q

Which is prostaglandin E1?

A

Misoprostol

120
Q

Adverse effects of prostaglandin E1? (4)

A
  1. Uterine tachysystole with fetal HR deceleration
  2. Mom shiver
  3. Mom pyrexia
  4. Mom diarrhea
121
Q

Are there any contraindications for oxytocin/pitocin?

A

NONE

122
Q

How should methergine and hemabate be given?

A

IM; NOT IV

123
Q

Develops before 20 wks gestation; SBP >140 or DBP >90

A

Chronic pre exisitng HTN

124
Q

Develops after 20 wks but no proteinuria or end organ damage?

A

Gestational HTN

125
Q

New onset HTN and either proteinuria or end organ dysfunction after 20 wks of gestation

A

Preeclampsia

126
Q

Preeclampsia: SBP, DBP, previous BP, proteinuria

A

SBP: >140 or DBP: >90 on 2 occasions
Previously normal BP
Proteinuria >300 mg/d

127
Q

Preeclampsia with seizures

A

Eclampsia

128
Q

Preeclampsia treatment (4)

A
  1. Delivery
  2. Bedrest
  3. AnitHTN therapy
  4. Magnesium sulfate to prevent convulsions
129
Q

6 antiHTN agents?

A
  1. Hydralazine
  2. Labetalol
  3. Nifedipine
  4. Sodium nitroprusside
  5. Fenoldopam
  6. Nitroglycerin
130
Q

What is hydralazine and how long does it last?

A

Arterial vasodilator as well as uterine and renal vasculature
Up to 6 hrs

131
Q

2 adverse effects of hydralazine?

A
  1. Reflex tachycardia

2. Increase myocardial contractility

132
Q

What is used for prevention of maternal seizures in preeclampsia pts?

A

Magnesium sulfate

133
Q

MOA of magnesium sulfate?

A

Competitively inhibits action of Ca in sarcoplasmic reticulum binding sites, reducing level of intracellular Ca and results in smooth muscle relaxation

134
Q

Magnesium sulfate dosing?

A

Bolus 4 g (2-6) over 20min

Infusion 1-2 g/hr

135
Q

Goal of maintaining Mg concentration?

A

2-3.5 mEg/L

136
Q

What Mg concentration causes cardiac arrest?

A

> 25

137
Q

4 possible MgSO4 adverse effects?

A
  1. Possible tocolytic effect
  2. Maternal flushing, palpitations, chest pain, nausea, blurred vision, sedation
  3. Decrease fetal HR due to placental transfer
  4. Generalized muscle weakness
138
Q

6 anesthetic considerations for MgSO4?

A
  1. Decrease SVR
  2. Both neuoaxial and GA safe but more hypotension
  3. Avoid redose NMB before sux
  4. Maintenance dose NMB reduced
  5. Reduce MAC of volatile agent
  6. May interfere with platelet function
139
Q

Treatment of MgSO4 toxicity?

A

CaCl or CaGluc 10-15 mg/kg over 5-10 min

140
Q

Vd in pregnant pts

A

Increased but systemic pseudocholinesterase activity is decreased

141
Q

Anesthesia routine (4)

A
  1. Epidural or general
  2. 1 MAC of volatile agent until delivery of infant
  3. N2O up to 70% & volatile reduce to .75% (low amnesia for uterus)
  4. NMB muscle relaxant; cisatracurium, vecuronium, roc (if receiving MgSO4 then will have prolong block)