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NUNA 693 Obs/Regional > OB: Uterine Blood Flow and Placental Transfer > Flashcards

OB: Uterine Blood Flow and Placental Transfer Flashcards

1
Q

blood supply comes mainly from the _____ _____ with lesser variable contribution from the _____ _____

A

uterine arteries
ovarian arteries

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2
Q

blood pathway of starting at internal iliac to intervillous space

A

Internal Iliac > Uterine Artery > Arcuate Arteries > Radial Arteries > Spiral Arteries > Intervillous space

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3
Q

Abdominal Aorta > _____ Artery > _____ plexus

A

Ovarian
Uteroovarian

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4
Q

Uterine blood flow _________ to meet the needs of the growing uterus and fetus

A

increases

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5
Q

uterine arteries are maximally _____

A

dilated

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6
Q

Placental blood flow is supplied via the maternal _____, _____, and _____ arteries

A

arcuate, radial, & spiral

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7
Q

Pressure ____ ____ towards intervillous space

A

down shifting

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8
Q

UBF: Increases to ______ mL/minute at term

A

800

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9
Q

UBF: ____ mL/min to the myometrium

A

150

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10
Q

UBF: Remainder to ___ ____

A

intervillous space

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11
Q

UBF: _______% of Cardiac output

A

10-20%

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12
Q

UBF: ____ mL/min to the decidua

A

100

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13
Q

What decrease UBF?
C_____

A

Contractions

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14
Q

What decrease UBF?
Maternal _____

A

hypotension

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15
Q

What decrease UBF?
Maternal ______

A

HTN

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16
Q

What decrease UBF?
Exogenous _______

A

vasoconstrictors

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17
Q

What decrease UBF?
____ _____ toxicity

A

local anesthetic

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18
Q

What decrease UBF?
______ uterine tone with sympathetic block

A

increased

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19
Q

Causes of decreased uterine arterial pressure
_____ position (aortocaval compression)
H______/h______
Drug induced hypotension
Hypotension during _____ ____

A

Supine
Hemorrhage/Hypovolemia
sympathetic blockage

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20
Q

Causes of increased uterine venous pressure
_______ compression
Uterine _____
Drug induced uterine ______
Skeletal muscle hypertonus (seizures, Valsalva maneuver)

A

Venalcaval
contraction
tachysystole

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21
Q

Endogenous vasoconstrictors that lead to increased uterine vascular resistance (2)

A

Catecholamines (stress)
Vasopressin (in response to hypovolemia)

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22
Q

Exogenous vasoconstrictors that lead to increased uterine vascular resistance (3)

A

Epinephrine
Vasopressors (phenylephrine > ephedrine)
LAs (in high concentrations)

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23
Q

Uterine Blood Flow =

A

(uterine perfusion pressure) / (uterine vascular resistance)

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24
Q

Neuraxial Anesthesia: increased uterine blood flow as a result of:
_____ relief
decreased ______ activity
decreased maternal ______

A

pain
sympathetic
hyperventilation

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25
Q

Neuraxial Anesthesia: decreased uterine blood flow as a result of:
Hypo_____
unintentional ____ _____ of LA and/or ephedrine
absorbed ____ (little effect)

A

hypotension
IV injection
LA

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26
Q

Commonly used induction agents have ____ ____ _____ effect on uteroplacental blood flow

A

little to no

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27
Q

uteroplacental blood flow may be affected indirectly by (2)

A

BP changes
Sympathetic response (laryngoscopy/intubation)

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28
Q

Inhalational Agents have ___ _____ _____ effect on uterine blood flow

A

little to no

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29
Q

Deeper planes of anesthesia are associated with _____ in C.O., maternal blood pressure, and uterine artery blood flow

A

reductions

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30
Q

A dose dependent reduction in uterine tone by inhalational agents would be expected to ______________ blood flow

A

increase

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31
Q

based on blood flow, how would that impact what inhalational agent to use

A

Based on blood flow there is little to no reason to choose one inhalational agent over another

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32
Q

Umbilical arteries (2) carry O2 _____ saturated blood from the fetus TO the placenta

A

POOR

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33
Q

Blood enters fetal circulation via ____ ____

A

ductus venosus

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34
Q

____ _____ carries O2 rich blood to the fetus

A

Umbilical vein

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35
Q

Inadequate fetal oxygenation occurs if maternal SBP drops below ____ mmHg in awake healthy patients during LEA (labor epidural analgesia)

A

100 mmHg

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36
Q

Oxygenated blood: pathway from Internal Iliac to Fetal RA

A

Oxygenated blood: Internal Iliac > Uterine Artery > Arcuate Arteries > Radial Arteries > Spiral Arteries > Intervillous space > Umbilical vein > Fetal Ductous Venosus > Fetal IVC > Fetal RA >

37
Q

Deoxygenated blood from fetus back to intervillous space

A

Fetal Umbilical Arteries (2) > Intervillous space

38
Q
A
  1. arteries
  2. vein
  3. fetal capillaries
  4. intervillous space
  5. maternal spiral artery
39
Q

Placental transfer of drugs is dependent on (4)

A
  1. concentration gradient (larger gradient, more crosses)
  2. Molecular weight (smaller than 500 Da cross easily, greater than 1000 Da cross poorly)
  3. Lipid solubility (high lipid solubility cross easily)
  4. Ionization (highly ionized = water soluble = decreased diffusion)
40
Q

Dilution of drugs in maternal blood, then ____ blood, then ____ blood before being circulated in the fetus.

A

intervillous
placental

41
Q

Drug further diluted in fetal blood, goes through a sort of first pass thought the ____ ( ___ ___ ).

A

liver (ductus venosus)

42
Q

Fetal Drug Dilution Factors

Dilution in _____ blood

A

intervillous

43
Q

Fetal Drug Dilution Factors

Some absorbed by _____

A

placenta

44
Q

Fetal Drug Dilution Factors

Diluted in ____ blood

A

placental

45
Q

Fetal Drug Dilution Factors

Distribution in fetal _____ volume

A

intervascular

46
Q

Fetal Drug Dilution Factors

Redistribution to fetal ____

A

tissues

47
Q

Fetal Drug Dilution Factors

20% of fetal cardiac output returns ____ to placenta without ______

A

directly
circulating

48
Q

Fetal Drug Dilution Factors

Not all umbilical venous blood bypasses the ____ via ____ _____

A

liver via ductus venosus

49
Q

The fetus and neonate do metabolize drugs, just at a ___ ____ rate than adults.

A

much slower

50
Q

Fetal circulation takes drugs through the ____ first (mostly)

A

liver

51
Q

Any excreted drugs would later be swallowed as ____ ____

A

amniotic fluid

52
Q

Elimination of drugs by the fetus is mostly dependent on ____ ____

A

placental transfer

53
Q

Maternal Pharmacokinetic Basics

Absorption and Uptake
Decreased ____ & Increased ___ leads to increased pulmonary uptake of inhalational agents

A

FRC
MV

54
Q

Maternal Pharmacokinetic Basics

Distribution:
Increased ___ increases distribution to all tissues
Total body water increases on average by ____ leading to Increased volume of distribution for _____ drugs

A

CO
8L
hydrophilic

55
Q

Maternal Pharmacokinetic Basics

Metabolism:
Although CO is increased, ____ blood flow is not markedly increased
Some _____ _____ have increased activity, others have decreased activity

A

hepatic
CYP450 enzymes

56
Q

Maternal Pharmacokinetic Basics

Elimination
___ and ___ increase so drugs that are excreted by the kidneys unchanged (___) are eliminated faster.

A

Renal blood flow and GFR, cephalosporins

57
Q

PK principles: (6)

A
  • lipid solubility
  • protein binding
  • tissue binding
  • pKa
  • pH
  • blood flow
58
Q

Substances are transferred across the placenta by one of several mechanisms. (5)

A
  • simple diffusion
  • simple diffusion via channels
  • facilitated diffusion
  • active transport
  • endcytosis
59
Q

Drugs that Readily Cross the Placenta

Anticholinergic Agents (2)

A

atropine and scopolamine

60
Q

Drugs that Readily Cross the Placenta

Antihypertensive Agents (3)

A
  • BBs
  • SNP
  • NTG
61
Q

Drugs that Readily Cross the Placenta

Benzos and Opioids

A

Benzos - specifically diazepam and midazolam
opioids was general

62
Q

Drugs that Readily Cross the Placenta

_____ anesthetics

A

Local

63
Q

Drugs that Readily Cross the Placenta

vasopressor

A

ephedrine

64
Q

Drugs that Readily Cross the Placenta

induction agents (4)

A

propofol
ketamine
etomidate
thiopental

65
Q

Drugs that Readily Cross the Placenta

Inhalational agents (5)

A

Halothane
Isoflurane
Sevoflurane
Desflurane
N2O

66
Q

Drugs that Do NOT Readily Cross the Placenta

anticholinergic agent (1)

A

Glyco

67
Q

Drugs that Do NOT Readily Cross the Placenta

anticoagulants (1)

A

heparin

68
Q

Drugs that Do NOT Readily Cross the Placenta

Muscle Relaxants

A

Depolarizing: Succinylcholine
Nondepolarizing Agents

69
Q

Drugs that Do NOT Readily Cross the Placenta

Vasopressor (1)

A

Phenylephrine

70
Q

What are the 6 pharmacokinetics principles?
[Pharmacokinetic Principles]

A

Lipid solubility
Protein Binding
Tissue Binding
pKa
pH
Blood Flow

71
Q

Increased Transfer Decreased Transfer
Size: molecular weight-
[Pharmacokinetic Principles]

A

Increased < 1000
Decreased >1000

72
Q

Increased Transfer Decreased Transfer
Charge of molecules-
[Pharmacokinetic Principles]

A

Increased: uncharged, Decreased: Charged

73
Q

Increased Transfer Decreased Transfer
Lipid solubility-
[Pharmacokinetic Principles]

A

Increased Lipophilic
Decreased Hydrophilic

74
Q

Increased Transfer Decreased Transfer
pH vs drug pKa
[Pharmacokinetic Principles]

A

Increased-Higher porportion of unionized drug in
maternal plasma
Decreased-Higher proportion of ionized drug in material plasma

75
Q

Increased Transfer Decreased Transfer
Placenta efflux transporter proteins (e.g, P-glycoprotein)
[Pharmacokinetic Principles]

A

Increased: Absent
Decreased: Present

76
Q

Increased Transfer Decreased Transfer
Binding protein type
[Pharmacokinetic Principles]

A

Increased: Albumin (lower binding affinity)
Decreased: Alpha1 acid glycoprotein (AAG) higher binding affinity

77
Q

Increased Transfer Decreased Transfer
Free (unbound) drug fraction
[Pharmacokinetic Principles]

A

Increased: High
Decreased: Low

78
Q

Substances are transferred across the placenta by one of several mechanisms. (5)

[Transport Mechanisms]

A

Simple diffusion, Simple diffusion via channels, Facilitated diffusion, active transport and endocytosis. (see image slide 24)

79
Q

Anticholinergic Agents
At___
Sc___
[Drugs that Readily Cross the Placenta]

A

Atropine
Scopolamine

80
Q

Antihypertensive Agents
BB___
N___ide
N___ine
Drugs that Readily Cross the Placenta

A

Beta Blockers
Nitroprusside
Nitroglycerine

81
Q

Benzodiazepines
Di___
Mi___
Drugs that Readily Cross the Placenta

A

Diazepam
Midazolam

82
Q

Op___
L…A___
Drugs that Readily Cross the Placenta

A

Opioids
Local Anesthetics

83
Q

Vasopressor
Ep___(?)
Drugs that Readily Cross the Placenta

A

Ephedrine
(not sure why this is listed as a vasopressor)

84
Q

Induction Agents
Pro___
Ke___
Et___
Th___
Drugs that Readily Cross the Placenta

A

Propofol
Ketamine
Etomidate
Thiopental

85
Q

Inhalation Agents
Ha___
Is___
Se___
De___**
N…Ox___
Drugs that Readily Cross the Placenta

A

Halothane, Isoflurane, Sevoflurane, Desflurane**, Nitrous Oxide

86
Q

Anticholinergic Agent:
Drugs that Do Not Readily Cross the Placenta

A

Glycopyrrolate

87
Q

Anticoagulants
Drugs that Do Not Readily Cross the Placenta

A

Heparin

88
Q

Muscle Relaxants
Drugs that Do Not Readily Cross the Placenta

A

Depolarizing: Succinylcholine
Nondepolarizing Agents

89
Q

Vasopressor
Drugs that Do Not Readily Cross the Placenta

A

Phenylephrine

NUNA 693 Obs/Regional (13 decks)

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