Obstetric Flashcards
1
Q
MAC requirements for inhaled anesthetics (2)
A
- Reduce by 30-40% at peak
2. Returns to normal about 3 days after delivery
2
Q
Proposed mechanism for reduce MAC requirements?
A
increased circulating endorphins; 10-20fold increase in progesterone late in pregnancy, have CNS depressant effects
3
Q
3 examples of reduce in MAC requirements?
A
- Inspired dose of volatile agent to supplement neuro axial anesthesia for sedation, may cause loss of consciousness
- Increase sensitivity to benzodiazepines and barbiturates
- No change in Propofol or ketamine doses
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
5
Q
Does plasma volume or RBC volume increase and what can that cause?
A
Plasma volume; dilutional anemia (similar for some drugs)
6
Q
At term what is a normal Hg?
A
11.6g/dL
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
8
Q
Increase CO and HR leads to what early and then eventually what?
A
early: SV
later: SV and HR
9
Q
Is myocardial contractility changed during pregnancy?
A
NO
10
Q
HR peaks at what bpm at term?
A
10-20 bpm
11
Q
What 3 things decreased with pregnancy?
A
Systemic resistance, SBP, DBP
12
Q
Dilutional anemia new “normal” values?
A
Hgb 9-11 g/dL (depends on iron supplementation)
13
Q
What would be suggest if Hgb >13 g/dL?
A
hemoconcentration, need to look for cause (preeclampsia)
14
Q
Platelet count and function?
A
No change in count to modest decline of ~10%
15
Q
Pregnancy is what kind of coagulable state?
A
hypercoagulable (increase procoagulant factors, decrease fibrinolytic system and natura inhibitors of coagulation)
16
Q
Why is pregnancy in hypercoagulable state?
A
minimize intrapartum blood loss
17
Q
Hypercoagulable state may increase what risk during pregnancy and post parturm?
A
thromboembolism (6fold)
18
Q
What does the fibrinolytic system get activated?
A
postpartum period
19
Q
Hemoglobin has what kind of estimated change?
A
decrease 20%
20
Q
Gastric emptying?
A
normal throughout gestation but slows with onset of painful contractions and parenteral opioids
21
Q
What can increase gastric emptying?
A
clear liquids
22
Q
When does gastric emptying return to normal?
A
18-24 hrs
23
Q
Is gastric emptying impacted by Na channel blocking LA?
A
NO
24
Q
Gastric secretions?
A
reduced (increased pH); but amount of secretions are unchanged
25
Lower esophageal sphincter (LES) tone?
reduces; increase risk of aspiration and regurgitation
26
What is LES barrier impacted by? (2)
1. Progesterone adn estrogen relax the smooth muscles of LES
2. Elevation/rotation of stomach by enlarging uterus
27
What 2 things can cause changes in liver function?
increased estrogen and progesterone
28
Hepatic BF?
BF and liver size remain unchanged despite increase CO
29
Splanchnic, portal and esophageal venous pressure?
increase
30
Serum albumin concentration?
reduce by 60% due to increase plasma volume; reduced total protein
31
Gamma globulin pregnancy effect?
no change to slight decrease
32
Fibrinogen pregnancy effect?
reduction 50%
33
Bilirubin pregnancy effect?
no change
34
ALP pregnancy effect?
increase 2-4 fold
35
GGTP pregnancy effect?
reduced
36
AST and ALT pregnancy effect?
none
37
TG and cholesterol pregnancy effect?
increased 2-3 fold
38
Hb pregnancy effect?
decrease 20%
39
Platelets pregnancy effect?
no change or decrease about 10%
40
Clotting factors (7, 8, 10, 12) pregnancy effect?
increase (30-250%)
41
Fibrinogen pregnancy effect?
increase
42
Protein S pregnancy effect?
decrease 40-50%
43
BV pregnancy effect?
increase 35%
44
Plasma volume pregnancy effect?
increase 55%
45
CO pregnancy effect?
increase 40-50%
46
SV pregnancy effect?
increase 25-30%
47
Pulse pressure pregnancy effect?
increase
48
HR pregnancy effect?
increase 15-20%
49
Systemic Resistance pregnancy effect?
decrease 15-20% (trimester specific)
50
SBP pregnancy effect?
decrease 5%
51
DBP pregnancy effect?
decrease 15%
52
Renal BF?
increase 75%
53
Renal afferent and efferent arterial resistance and when does it return to normal?
reduced; 6 months postpartum
54
GFR?
increase from 100-150 ml/min by 2nd trimester
55
BUN and sCr?
reduces; normal and slightly higher values may signal poor renal function
56
What causes gestational DM?
reduction in renal tubular reabsorption of glucose
57
Do you get proteinuria?
yes
58
Thyroid gland?
englarges with increased vascularity
59
T3 and T4?
increase by 50%
60
TSH?
slight decline early then returns to normal
61
Tissue sensitivity to insulin and why?
reduced due to placental hormone
62
Fasting blood glucose?
lower
63
Relaxin levels?
increase to prepare for delivery
64
An agent that, under certain conditions of exposure, has the potential to cause abnormal fetal growth and development
Teratogen
65
Capability of producing congenital abnormalities, major or minor malformations
Teratogenicity
66
What can cause different outcomes resulting from drug exposure for teratogen?
Stage of pregnancy
67
teratogen could destroy the embryo leading to a terminated pregnancy; likely unknown to the mother. Alternatively, exposure may cause no problems.
“All or nothing” effect
| Week 1 & 2; blastogenesis
68
Organ systems are developing during this stage; teratogenic exposures may result in organ system abnormalities (heart or neural tube defects)
Structural anomalies
| 18-60 days; organogenesis
69
Exposure to teratogens may result in growth retardation, CNS abnormalities or extreme cases (death)
Remainder of the pregnancy
| >60 days; growth and maturation
70
Are there any drugs known to be safe for teratogens?
NO
71
Where is the exchange for a number of substances (nutrients, gases, antibodies, and some meds)
Placenta
72
What 4 drug properties influence placental transfer?
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
When is elective surgery delayed?
2-6 weeks postpartum
74
If cannot delay elective surgery, when is best time for it?
2nd trimester
75
Why is induction and emergency form anesthesia more rapid? (2)
1. Increased minute vent
| 2. Decreased functional residual capacity
76
What is considered safe to use for non-obstetric surgery? (6)
```
Propofol (2mg/kg)
Ketamine (1-2 mg/kg)
Sux (1.5 mg/kg)
Epidural analgesic
Opioids
Acetaminophen
```
77
What should be AVOIDED >32 wks gestation?
NSAIDs
78
Do you need to change your dosage for sux?
No because Vd increased but systemic pseudocholinesterase activity decreased
79
5 preterm labor management drugs?
```
CCB
B2 agonist
NSAID
Antenatal corticosteroids
Magnesium sulfate
```
80
Is CCB or B2agonist superior?
CCB
81
Mechanism of CCB?
Decrease Ca movement into smooth muscle cells through modulation of the duration of opening of the Ca channel
82
Which CCB drug is most common?
Nifedipine
83
Which CCB is not recommended?
Nicardipine
84
Most common adverse effect of CCB?
Hypotension
85
What can CCB lead to?
Refractory postpartum hemorrhage in setting uterine atony because oxytocin and prostaglandin agonist works through CCB mechanism to treat atony
86
Mechanism of action for beta 2 agonists?
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
When is beta2 agonist most useful?
Uterine hypertonus
88
What has a black box warning for concerns of maternal heart problems and death?
Beta 1 and 2 agonists
89
B1 affect what and B2 affect what?
B1: HR
B2: DBP
90
How long do you delay anesthesia after beta agonist given?
1 hr
91
Prostaglandin inhibitors (NSAIDs) are effective at what?
Delaying delivery in setting of preterm labor
92
Mechanism of action of prostaglandin inhibitors?
Inhibit COX1 and COX2 enzymes
93
Ketorolac max dose?
120 mg/day
94
Does nitroglycerin affect the fetus?
No
95
IV dose of nitroglycerin?
50-100mcg
96
Magnesium sulfate should be used as a caution when using for what?
Preeclampsia/eclampsia
97
Uterotonic meds are used for what 5 cases?
1. Uterine atony
2. Postpartum hemorrhage
3. Induction of labor
4. Pregnancy termination
5. Cervical ripening
98
Oxytocin is natural hormone and called what?
Nonapeptide
99
Pitocin is a synthetic hormone and called what?
Octapeptide
100
Which uterotonic med is more selective for uterine receptors, minimizing renal anti diuretic hormone effects?
Pitocin; synthetic hormone; octapeptide
101
Mechanism of action for oxytocin/pitocin?
Oxytocin acts on G protein receptors, activating Ca channels, increasing local prostaglandin production to induce uterine smooth muscle contraction
102
How many oxytocin/pitocin for labor induction?
1-2 units/min
103
How many oxytocin/pitocin is needed for uterine atony?
10-40 units diluted in a liter of isotonic fluid
104
4 maternal adverse effects to oxytocin/Pitocin?
1. Hypotension
2. Fluid retention
3. Tachysystole (>5 contractions in 10min averaged over 30min)
4. Uterine rupture due to uterine hyperstimulation
105
2 fetal adverse effects from oxytocin/pitocin?
1. Hypoxia
| 2. Bradycardia due to hypertonic contractions
106
A synthetic ergot alkaloid
Methylergonovine/methergine
107
MOA for methergine?
Causes dose dependent increase in uterine contraction and tone. Mediated via alpha adrenergic receptors in uterus
108
4 adverse effects for methergine?
1. Peripheral vasoconstriction so increase BP
2. Increased pulmonary artery pressure
3. Coronary artery vasospasm
4. Nausea and vomiting
109
Dosing for methergine?
IM .2mg over 2-4 hrs (max .8)
110
Who do you avoid methergine with?
HTN/preeclampsia; peripheral vascular disease and ischemic heart disease
111
If pt gets HTN with methergine, how do you treat it?
Hydralazine and nitroglycerin
112
Naturally occurring hormones, which enhance uterine contractility and cause vasoconstriction
Prostaglandins E2, F2a, E1
113
Together with oxytocin essential for parturition
Endogenous hormones
114
Dose dependent increase in uterine tone
Exogenous drug
115
MOA of prostaglandins?
Increase myometrial Ca concentrations which lead to increased myosin light chain kinase activity and uterine contraction
116
4 reasons prostaglandins are used:
1. Uterine atony
2. Induction of labor
3. Cervical ripening
4. Induce abortion
117
Common dosage for prostaglandin (carboprost, hemabate)?
IM of .25 mg can repeat every 15min for total dose of 2mg
118
When should carboprost; hemabate be avoided? (5)
1. Hypersensitivity
2. Asthma
3. HTN
4. Renal impairment
5. Hepatic impairment
119
Which is prostaglandin E1?
Misoprostol
120
Adverse effects of prostaglandin E1? (4)
1. Uterine tachysystole with fetal HR deceleration
2. Mom shiver
3. Mom pyrexia
4. Mom diarrhea
121
Are there any contraindications for oxytocin/pitocin?
NONE
122
How should methergine and hemabate be given?
IM; NOT IV
123
Develops before 20 wks gestation; SBP >140 or DBP >90
Chronic pre exisitng HTN
124
Develops after 20 wks but no proteinuria or end organ damage?
Gestational HTN
125
New onset HTN and either proteinuria or end organ dysfunction after 20 wks of gestation
Preeclampsia
126
Preeclampsia: SBP, DBP, previous BP, proteinuria
SBP: >140 or DBP: >90 on 2 occasions
Previously normal BP
Proteinuria >300 mg/d
127
Preeclampsia with seizures
Eclampsia
128
Preeclampsia treatment (4)
1. Delivery
2. Bedrest
3. AnitHTN therapy
4. Magnesium sulfate to prevent convulsions
129
6 antiHTN agents?
1. Hydralazine
2. Labetalol
3. Nifedipine
4. Sodium nitroprusside
5. Fenoldopam
6. Nitroglycerin
130
What is hydralazine and how long does it last?
Arterial vasodilator as well as uterine and renal vasculature
Up to 6 hrs
131
2 adverse effects of hydralazine?
1. Reflex tachycardia
| 2. Increase myocardial contractility
132
What is used for prevention of maternal seizures in preeclampsia pts?
Magnesium sulfate
133
MOA of magnesium sulfate?
Competitively inhibits action of Ca in sarcoplasmic reticulum binding sites, reducing level of intracellular Ca and results in smooth muscle relaxation
134
Magnesium sulfate dosing?
Bolus 4 g (2-6) over 20min
| Infusion 1-2 g/hr
135
Goal of maintaining Mg concentration?
2-3.5 mEg/L
136
What Mg concentration causes cardiac arrest?
>25
137
4 possible MgSO4 adverse effects?
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
6 anesthetic considerations for MgSO4?
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
Treatment of MgSO4 toxicity?
CaCl or CaGluc 10-15 mg/kg over 5-10 min
140
Vd in pregnant pts
Increased but systemic pseudocholinesterase activity is decreased
141
Anesthesia routine (4)
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)
