Ex1 OB 1 Flashcards

1
Q

CVS system changes in pregnancy

A

increased HR, SV

therefore increased CO

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2
Q

Respiratory system changes in pregnancy

A
  • displacement of diaphragm superiorly
  • decreased FRC
  • increased risk of apnea/dyspnea
  • hyperventilation
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3
Q

GI changes during pregnancy

A
  • N/V

- heart burn + acidity

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4
Q

Major cardiovascular changes during pregnancy

A
  • increased intravascular volume
  • increased cardiac output
  • decreased vascular resistance
  • supine HOTN
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5
Q

Changes to the heart during pregnancy

A

heart enlarges, displaces upward + to Left

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6
Q

Why does CO change during pregnancy?

A

Increase in both HR, SV

Decrease in SVR

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7
Q

Decreased SVR is due to

A

initiating factor: estrogens, progesterone, prostacyclin

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8
Q

CO is greatest when?

A

Right after delivery

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9
Q

When does moms CO return to baseline?

A

~ 2 weeks after delivery

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10
Q

What compensates for the blood loss during delivery?

A

contractions of engorged uterus provide 300-500mL autotransfusion into maternal circulation –> increased CO

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11
Q

Common cause of moms HOTN

A

While laying flat on back: weight of placenta + amniotic sac can compress IVC

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12
Q

Increased risk of ____ in mom d/t decreased vascular resistance/venodilation?

A

epidural vein puncture

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13
Q

While placing epidural, what should be ensured?

A
Remaining midline 
(avoid epidural veins)
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14
Q

90% of pregnant women have a ____

A

late systolic or ejection murmur

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15
Q

Common murmurs in pregnant women are attributable to

A

increased stroke volume

decrease in blood viscosity

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16
Q

At term, what may be seen on the CXR?

A

Larger cardiac silhouette d/t diaphragm shifting heart up + Left

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17
Q

What changes may be seen in 3rd trimester on EKG?

A

Increased incidence of dysrhythmias (PAC, PVC, SVT) d/t Left Axis shift on ECG

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18
Q

Second trimester

A

20-28 weeks gestation

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19
Q

important but preventable cause of fetal distress

A

aortocaval compression

-after 20-28w gestation

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20
Q

aortocaval compression

A

gravid uterus obstructs aorta + inferior vena cava (while supine) –> no blood supply to placenta (uteroplacental circulation) –> no blood supply to baby –> asphyxia

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21
Q

What will be seen on the fetal heart monitor if aortocaval syndrome occurs?

A

Late decelerations

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22
Q

How to avoid aortocaval syndrome?

A

Tilt parturient to left side

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23
Q

3rd trimester

A

29-40 weeks

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24
Q

Cause of LE edema, venous stasis

A

Chronic partial caval obstruction in 3rd trimester

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25
Q

Beginning location of aortic compression

A

L3-L4

upper body BP may remain normal

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26
Q

Changes in blood volume during pregnancy are due to

A

increased mineralocorticoid activity –> sodium retention + increased body water content

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27
Q

Blood volume changes during pregnancy

A

increased:
plasma volume ( +50%
total blood volume (+45%)
red cell volume (+25%)

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28
Q

Which increases more during pregnancy: plasma volume or red cell volume?

A

Plasma volume

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29
Q

Changes in blood volume lead to ____ during pregnancy

A

relative dilutional anemia

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30
Q

TBV at term

A

85-100 mL/kg

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31
Q

Healthy parturients can tolerate up to _____ mL blood loss without a transfusion

A

1500mL

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32
Q

High Hgb levels may indicate

A

Normal Hgb > 11
High Hgb = > 14
*may indicate low volume state caused by preeclamsia, HTN, or inappropriate diuresis

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33
Q

Approximate intravascular volume change

A

1000-1500 mL

*helps compensate for EBL

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34
Q

EBL vaginal

A

300-500 mL

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35
Q

EBL section

A

800-1000mL

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36
Q

Coagulation changes during pregnancy

A
  • coagulation factors + fibrinogen increase

- platelets remain same or decrease 10% during 3rd trimester

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37
Q

Factors that increase during pregnancy

A

I, VII, VIII, IX, X, and XII

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38
Q

Factors that decrease during pregnancy

A

XI and XIII

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39
Q

Coagulation lab changes in pregnancy

A

PT -20%
PTT -20%
No change: platelets or bleeding time

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40
Q

Coagulation lab changes in pregnancy: thromboeleastography

A

hypercoagulable

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41
Q

Coagulation lab changes in pregnancy: antithrombin III

A

decreased

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42
Q

Coagulation lab changes in pregnancy: fibrin degradation products

A

increased

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43
Q

Coagulation lab changes in pregnancy: plasminogen

A

increased

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44
Q

What may worsen airway edema in pregnancy?

A
  • preeclampisa
  • trendelenberg position
  • Tx w/ tocolytics
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45
Q

Average size ETT in pregnancy

A

6-6.5

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46
Q

changes in airway during pregnancy

A
  • capillary engorgement of mucosal lining
  • mucous membranes = friable
  • swelling of false vocal cords (narrowed glottis)
  • weight gain/breasts = hinder laryngoscopy
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47
Q

key for successful airway placement

A
  • proper axis alignment (via positioning)
  • short laryngoscopy handles
  • know where glidescope is at all times (video laryngoscope)
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48
Q

What does diaphragmatic elevation cause?

A
  • less negative intrathoracic pressure

- decreased FRC, ERC, RV (20%)

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49
Q

significant PFT changes

A

compensatory increase in thoracic anterior-posterior diameter

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50
Q

What change in moms body causes the majority of respiratory changes?

A

Hormones (increased progesterone)
+
Enlarged Uterus

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51
Q

What physical changes in moms body causes respiratory changes?

A

Enlarged uterus –> ribcage becomes wider, back broader (+ diaphragm pushed up)

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52
Q

Why is mom at a higher risk of rapid oxygen desaturation during periods of apnea?

A

Combo:

decreased FRC + increased O2 consumption

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53
Q

What is mandatory prior to GA in pregnant patients?

A

Preoxygenation

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54
Q

Risk of pain/anxiety during labor in relation to respiratory system

A

increased RR –> hypocapna, faintness, perioral numbness

–> fetal hypoxia/distress

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55
Q

What occurs to 2,3-DPG during pregnancy?

Why does this change?

A
  • 2,3-dpg concentration increases

- lowers affinity of maternal Hgb for O2

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56
Q

Reason for change of 2,3-dpg

A

Lowers moms affinity of Hgb for O2 –> facilitates dissociation of oxygen from Hgb thru intervillous space in placenta, enhances delivery of O2 to growing fetus

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57
Q

Dissociation curve is affected during pregnancy how?

A

increased 2,3-DPG shifts O2 Hgb dissoc. curve to the Right (P50 increases from 27-30 mmHg)

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58
Q

Most significant Respiratory changes

A

Decreased FRC
No change in VC
Increased TV
Decreased ERV

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59
Q

When does mom’s minimal alveolar concentration return to normal?

A

3 days post-partum

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60
Q

Effect of pregnancy on MAC

A

decreases by up to 40%

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61
Q

Cause of changed MAC during pregnancy

A

Progesterone + B-endorphin

62
Q

Pregnant patients reaction to local anesthetics + cause

A

enhanced sensitivity d/t increased spread of LA in epidural/subarachnoid spaces (occurs d/t epidural venous engorgement)

63
Q

Parturient is highly dependent on _____ for blood pressure control

A

SNS

64
Q

D/t increased SNS role in parturient, what occurs after regional anesthesia?

A

significant decrease in BP

65
Q

When does SNS return to normal?

A

36-48 hours postpartum

66
Q

cause of constipation during pregnancy

A

progesterone –> slowed GI motility –> enhanced water absorption

67
Q

All moms after ______ (time) are at risk for what?

A

12 weeks +
increased risk for aspiration
RSI

68
Q

If GA is administered to parturient, what should also be given?

A
  • nonparticulate antacid (Bicitra)
  • H2 blocker
  • Reglan (consider)
69
Q

What occurs to GFR during pregnancy?

A
  • Increased by 50% in 1st trimester

- declines to normal in 3rd trimester

70
Q

Hepatic effects during pregnancy

A

Serum cholinesterase activity decreases by ~ 30%

NOT clinically relevant for sux/mivacurium

71
Q

When does pseudocholinesterase activity return to normal?

A

6 weeks postpartum

72
Q

Effect of pregnancy on urine labs

A
Mild glucosuria (1-10g/dL) or proteinuria (<300mg/dL)
d/t decreased renal tubular threshold for glucose/amino acids
73
Q

What joins the mother and fetus?

A

Placenta

74
Q

Uterine blood flow receives how much CO?

A

10% CO at term (600-700mL/min)

nongravid = 50mL/min

75
Q

T/F: the uterus is capable of autoregulation

A

False

76
Q

Uterine perfusion is dependent on

A
  • adequate driving pressure (uterine arterial pressure)
  • low uterine venous pressure
  • low uterine vascular resistance
77
Q

Increased uterine venous pressure _____ uterine blood flow

A

lowers

78
Q

Increased uterine venous pressure is d/t

A
Caused by:
Vena caval compression
Uterine contractions
Drug-induced hypertonus (oxytocin, LA)
Skeletal muscle hypertonus (seizures, valsalva)
79
Q

Increased uterine venous resistance ______ uterine blood flow

A

lowers

80
Q

Causes of increased uterine venous resistance

A
  1. endogenous vasoconstrictors

2. exogenous vasoconstrictors

81
Q

Endogenous vasoconstrictors that may cause increased UVR

A
  • catecholamines (stress)

- vasopressin (in response to hypovolemia)

82
Q

Exogenous vasoconstrictors that may cause increased UVR

A
  • epinephrine
  • vasopressors (phenyl, ephedrine)
  • local anesthetics in high concentrations
83
Q

Transfer of oxygen from mom to baby is dependent on

A

ratio of maternal UBF to fetal blood flow

84
Q

oxygenated blood from placenta has PaO2 of

A

40mmHg (80% saturated)

85
Q

fetal Hgb O2 dissociation curve is shifted ____

A

to the Left

HgbF > affinity for O2 than HgbM

86
Q

Fetal Hgb vs. Mom Hgb

A

Fetal ~ 15 g/dL

Mom ~ 12 g/dL

87
Q

transport of anesthetics from mom to baby occurs via

A

passive diffusion

88
Q

The rate of transfer of anesthetics from mom to baby occurs based on

A

Fick Principle

89
Q

Factors that promote rapid diffusion (anesthetics from mom to baby)

A
  • most anesthetics
  • NOT muscle relaxants
  • low molecular weight (<500 daltons)
  • high lipid solubility
  • low degree of ionization
  • low protein binding
90
Q

Ion trapping

A

fetal acidosis/low pH –> Rx = greater tendency to exist in ionized form, unable to diffuse back across placenta into maternal plasma –> Rx trapped in fetus (larger amounts)

91
Q

Rx used to stimulate/strengthen uterine contractions

A

oxytocics

92
Q

Rx used to delay/stop premature labor

A

tocolytics

93
Q

Oxytocics indications

A
  • induce/augment labor
  • control PP bleeding/uterine atony
  • induce therapeutic abortion
94
Q

Oxytocics

A
  • Oxytocin (pitocin)
  • Ergot alkaloids: Ergonovine (ergotrate), Methylerogonovine
  • Prostaglandin 15-methyl F2a
95
Q

Oxytocin MOA

A

Acts on uterine smooth muscle to stimulate the frequency and force of contractions; potent vasodilator

96
Q

Oxytocin S/E

A

CV effects: vasodilation, HOTN, tachycardia, arrhythmias

-high doses: may have antidiuretic effect + produce water intoxification, cerebral edema, convulsions

97
Q

Oxytocin dosage

A
  • diluted (20-40 u/L)
  • IV infusion
  • NEVER BOLUSED/PUSHED
98
Q

Risk of Oxytocin

A

Added preservative (chlorbutanol) = vasodilatory + negative inotropic effects

99
Q

Mom complains of N/V after oxytocin given, what can you assume?

A

BP will drop soon, even if it doesn’t show it yet. Slow down drip.

100
Q

Ergot Alkaloids - MOA

A

small doses: increase force + frequency of uterine contractions
high doses: contractions more intense, prolonged, resting tone increased, tetanic contractions occur

101
Q

Ergot Alkaloids - Rx

A

Most commonly used: methergine (methylerogonivine)

102
Q

Methergine A/E

A

CV: vasoconstriction, HTN augmented in presence of pressors

103
Q

Ergot Alkaloids: restrictions

A

Administration is restricted to 3rd stage of labor to control postpartum bleeding

104
Q

Methergine Administration

A
  • ONLY IM, 0.2mg

* prefer to give in thigh if spinal/epidural given

105
Q

Methergine - avoid in

A

PVD, HTN, CAD

106
Q

Methergine - why not IV?

A

associated with severe HTN, convulsions, stroke, retinal detachment, pulm edema

107
Q

Prostaglandin 15-methyl F2a

A

Hemabate

“carboprost tromethamine”

108
Q

Hemabate

A

3rd line Tx for uterine atony

goal: achieve uterine contraction

109
Q

Hemabate SE

A

transient HTN, severe bronchospasm, increased PVR

110
Q

Hemabate avoid in

A

asthmatics

111
Q

Hemabate administration

A

0.25mg IM
or intramyometrially (OB)
*must be refrigerated, $$$$

112
Q

Tocolytics are used for

A

delay or stop premature labor

  • used for fetuses gestational age 20-28 weeks
  • cervical dilation < 4cm + effacement < 80% associated with greater likelihood of terminating premature labor
113
Q

Tocolytics C/I

A
  • chorioamnionitis
  • fetal distress
  • intrauterine fetal demise
  • severe or chronic pregnancy-induced HTN
  • severe hemorrhage
114
Q

Terbutaline

A

Selective B2-adrenergic agonist

-used to inhibit preterm labor by producing myometrial inhibition by directly relaxing uterine smooth muscle

115
Q

Terbutaline SE

A
maternal bronchodilation
vasodilation
tachycardia
hyperglycemia
hypokalemia
hyperinsulinemia
metabolic acidosis
116
Q

What is magnesium sulfate used for in OB?

A

Preeclampsia + tocolytic agent

117
Q

MOA Mag Sulfate

A
  • reduces presynaptic release of Ach, which decreases hyperactivity at neuromuscular junction, thus weakening contractions
  • physiologic calcium antagonist, prevents increase of free intracellular calcium
118
Q

Mag Sulfate Administration

A
  1. Loading dose (4gm over 20 min)
    Followed by
  2. Infusion (2-4g/hr)
119
Q

Mag Sulfate SE

A

sedation, flushed face, hypotension, heart block, skeletal muscle weakness, respiratory depression, cardiac arrest
*flushed, weak, tired, soft, mushy

120
Q

Mag Sulfate Safety Precautions

A

Soft, boggy uterus –> high risk for PPH.

*have blood available, may need methergine, make sure T&C

121
Q

Other agents used to delay preterm labor

A

Indomethacin

Nifedipine

122
Q

Indomethacin MOA

A

NSAID that inhibits prostaglandins

123
Q

Nifedipine MOA

A

CCB

124
Q

most common drug given systemically to mother

A

opioids

125
Q

Opioids AE

A
  • cross placental circulation freely (RR depression in newborn), limited to early stages of labor OR regional not available
  • maternal SE: RR depression, N/V, altered MS
126
Q

If regional not available, best option?

A

Remifentanil bolus PCA

127
Q

Duramorph

A

preservative free morphine used in spinal/epidural

128
Q

Which opioid is not used and why?

A
  • Morphine not used

- excessive RR depression in neonate

129
Q

Duramorph administration

A

10mg/10mL (1mg/mL)
or
5mg/10mL (0.5mg/mL)

130
Q

Duramorph administration for spinal vs epidural

A

Spinal: use TB syringe (small amount)
Epidural: use normal syringe (bigger volume)

131
Q

Fentanyl use in OB

A

-adequate labor analgesia with minimal neonatal depression

132
Q

Maternal effects from Fentanyl

A

Maternal respiratory depression outlasts analgesia

-do NOT give near delivery

133
Q

Neonatal effects from Fentanyl

A
  • transient decrease in FHR variability noted

- doses of 1mcg/kg no adverse effects

134
Q

Fentanyl administration

A
25-50 mcg IV
peak 3-5 min
DOA 30-60min
Best: epidural/spinal 
Not-ideal: IV/PCA
135
Q

Reason for using Butorphanol or Nalbuphine

A

produce less N/V than other opioids

136
Q

Butorphanol MOA

A

“Stadol”

kappa-agonist + mu-antagonist, minimal affinity for delta receptors

137
Q

Butorphanol administration

A

1-2mg IV/IM

DOA up to 4h

138
Q

Nalbuphone MOA

A

“Nubain”

partial kappa-agonist + mu-antagonist, minimal delta activity

139
Q

Nalbuphone administration

A

10mg IV/IM

DOA up to 6h

140
Q

Nalbuphone Equipotent dose

A

10mg morphine = 10mg Nalbuphone

141
Q

Remifentanil compared to epidural

A

Remifentanil less effective than standard epidural

142
Q

PCA remifentanil dosage

A

0.25 mcg/kg q2 minutes

143
Q

Remifentanil characteristics

A
  • ultra-short acting with context sensitive 1/2t = 3.2 minutes
  • crosses placenta readily, rapidly redistributed + metabolized by fetus
144
Q

When is ketamine used?

A

Adjunctive, used for “hot spot”, subanesthetic doses = result in analgesia w/o LOC or loss in reflexes

145
Q

Disadvantages of Ketamine

A

HTN, emergence delirium

146
Q

Advantages of Ketamine

A

Maintains maternal CVS + uterine blood flow

147
Q

Ketamine dose

A

0.25-0.5 mg/kg IV
or
10 mg q2-5min IV

148
Q

High doses of ketamine may cause

A

High doses ( > 2mg/kg)
psychomimetic effects
increased uterine tone (+ low Apgar score)

149
Q

Typical duration of C/S

A

45 minutes

150
Q

Most frequently used inhalational technique

A

outside of US: 50:50 N2O + O2