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SNRAObPedGer > EXAM 3: Fetal Circulation > Flashcards

EXAM 3: Fetal Circulation Flashcards

1
Q

Parallel circuit

A

Both right and left ventricles provide systemic blood flow

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2
Q

Admixture blood

A

oxygenated with deoxygenated blood

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3
Q

PVR is because

A

High ; clamped down fluid filled

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4
Q

SVR is________

A

low

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5
Q

Placenta makes

A

SVR stay low

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6
Q

Right to left shunt

A

Right heart bypass lungs

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7
Q

Blood comes from the __________to the placenta

A

UMBILICAL VEIN Ductus venosus

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8
Q

The ductus venosus joined with

A

Inferior vena cava , and blood coming from LE

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9
Q

The ductus arteriosus

A

2nd place of shunting Right to left , bypass lung

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10
Q

Fetal circulation Right vs LEFT

A

RV output 2x that of left

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11
Q

Ratio of PVR to SVR

A

2:1 Right to left ratio

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12
Q

When placenta is removed

A

SPINAL ARTERY starts bleeding Uterus start Contracting stop mechanically from bleeding

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13
Q

Anesthesia Gases do what to the uterus

A

Relaxes uterus; may increase bleeding of spinal arteries after placenta has been cut off run MAC less percentage

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14
Q

INTERVILLUS SPACE Does mother and fetus blood mix? Thin membrane allows

A

where blood exchange happens Blood of fetus and mother’s blood DONT MIX passage of nutrients

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15
Q

RH factor relevant

A

Rh factor relevant in 2nd pregnancy

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16
Q

****Uteroplacental Perfusion: Originates from

A

the uterine and ovarian arteries

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17
Q

Blood flow to intervillous space

A

Maternal blood enters the basal plate of the placenta into the intervillous space • Nutrient exchange occurs with fetal blood coursing through the villi

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18
Q

2 circulations separate

A

• Normally, the two circulations are separate with no mixing

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19
Q

Uterine blood flow increases___ Prepreg. Level Pregnant _______ml at term

A

dramatically 50-100 ml/min PREGNANT 700-900ml min at term

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20
Q

Cardiac output to uterus increase from ______to ________

A

5% to approx 12% at term within the uterus , approxi 90% of blood flow is to the iNTERVILLOUS SPACE>

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21
Q

• Hemodynamic changes are result of_______ • Generalized systemic reduction in sensitivity to_______

A

-altered vascular responsiveness to endogenous vasoactive substances -vasoconstrictors during pregnancy

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22
Q

Uterine vascular responsiveness to vasoconstrictors What happens in PRE-ECLAMPSIA

A

• ↓ (meaning BP shouldn’t be higher than normal) Mother who developed preeclampsia lack the systemic reduction in sensitivity to catecholamines. LACK of refractoriness to resistance –> HTN

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23
Q

Uterine vessels are more sensitive to____________

A

alpha agonists than systemic vessels in general • More uterine vasoconstriction (increase vascular tone of mother, baby does worse, HR decelerates)

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24
Q

Changes in vascular reactivity during pregnancy may be due to:

A

• Altered receptor number and function (LESS) • Altered metabolism and clearance of drugs (increase BV) • Altered release of endogenous vasodilators or constrictors • Altered sensitivity to endogenous vasodilators (PGE2 and NO) or constrictors

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25
Q

Decrease sensitivity

A

to alpha agonist , EPINEPRHINE Phenylephrine and ANGIOTENSIN II more pronounce to uterus

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26
Q

Avoid hypotension in pregnant, you want to decrease BP but not too much to

A

cutting off the circulation of uterine blood flow

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27
Q

Enhanced release of vasodilators by vascular endothelium

A

Prostacyclin (PGI2) • Nitric Oxide (NO)

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28
Q

IMPORTANT there is alteration in which receptor?

A

Altered receptor mediated G-protein Most drugs work through GPCR

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29
Q

Determinants of Uterine Blood Flow

A

• U.B.F. is related to perfusion pressure and vascular resistance

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30
Q

UBF= Formula

A

uterine artery - uterine venous pressure/ uterine vascular resistance

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31
Q

U.B.F. will _____whenever perfusion pressure _______or uterine vascular resistance_________

A

↓ ↓ ↑

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32
Q

UBF and perfusion pressure

A

Direct relationship

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33
Q

UBF and uterine vascular resistane

A

Inverse

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34
Q

No supine

A

LEFT LATERAL TILT INSTEAD HEMODYNAMICALLY STABLE THERE IS DECREASED VENOUS RETURN, Decrease CO, decrease hypotension

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35
Q

FIRST SIGN OF HYPOTENSION

A

VOMITING

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36
Q

↓ Perfusion Pressure

A

▪ ↓ Uterine Arterial Pressure ▪ Supine position ▪ Hemorrhage/hypovolemia ▪ Drug-induced hypotension ▪ Hypotension during sympathetic blockade

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37
Q

Uterine Blood flow decreases when Vascular resistance increases

A

▪ ↓ Uterine Arterial Pressure ▪ Supine position ▪ Hemorrhage/hypovolemia ▪ Drug-induced hypotension ▪ Hypotension during sympathetic blockade

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38
Q

▪ ↑ Uterine Venous Pressure (VUDS) MOST COMMON Is

A

▪ Vena caval compression ▪ Uterine contractions MOST COMMON is ▪ Drug-induced uterine hypertonous (oxytocin, cocaine) ▪ Skeletal muscle hypertonous

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39
Q

THOSE things increase Vascular resistance

A

VASOPRESSIN ANGIOTENSIN II

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40
Q

Endogenous Vasoconstrictors (2) Prevent constriction (2)

A

Catecholamines Vasopressin Nitrous oxide , PGE2

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41
Q

Exogenous vasoconstrictors

A

Epinephrine ▪ Vasopressors (phenylepherine > ephedrine) ▪ Local Anesthetics (high concentrations)

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42
Q

The determinants of acute changes in uterine blood flow are

A

• systemic blood pressure • uterine venous pressure • uterine vascular resistance

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43
Q

Worst position

A

SUPINE

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44
Q

BEST POSITION

A

Left Lateral TILT

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45
Q

Position

A

Prone or ALL four positions

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46
Q

• Uterine blood flow if often reduced clinically

A

• Position • Drug induced hypotension • Uterine contractions and pushing efforts • Endogenous and exogenous vasoconstrictors

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47
Q

• Passive Transport-driven by DOES IT require energy ? what is mediated by ?

A

• Concentration gradients & electrochemical differences • Molecular weight • Lipid solubility • Degree of ionization • Membrane surface area/thickness. *** No use of cellular energy. Occurs thru lipid membrane or via protein channels

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48
Q

Facilitated Transport- Does it require ENERGY

A

• Intermembrane protein carriers move lipid-insoluble molecules down a concentration gradient (ie; glucose); no , just protein carrier

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49
Q

Active Transport DOES it require energy? Example

A

-movement of a substance against a gradient and across a cell membrane linked to cellular metabolic activity (energy) and a protein carrier; (ex: Na+/K+ ATPase pump)

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50
Q

• Pinocytosis Does it require energy ?

A

PLACENTA engorges -large protein macromolecules surrounded by membrane vesicles and moved through the cytoplasm to opposite membrane wall; requires cell energy

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51
Q

Fetal PO2 max is _____Why?

A

50-60 mmHg; because 1/5 the efficiency of the adult lung

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52
Q

CO2 is in the form of

A

Bicarbonate

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53
Q

Large partial pressure difference between Driven by O2 partial pressure difference between

A

Maternal and fetal blood

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54
Q

• Placenta transfers O2 for fetal growth/development Limited to ____not ______

A

• ~8 ml O2/min/kg fetal weight • Transfer is limited to flow not diffusion

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55
Q

Fetal Hgb has More affinity or less affinity ?

A

decreased levels of 2,3-DPG increasing O2 affinity

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56
Q

• Fetal PO2 max is 50-60 mmHg due to

A

Placenta being a venous equilibrator • Placenta’s high O2 consumption rate • Mixture of oxygenated umbilical blood and deoxygenated inferior vena caval blood from fetal lower extremitie

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57
Q

• Fetal PO2 max is 50-60 mmHg due to The mixture of _______ and __________ from _________ Which shunt mix Oxygenated UMBILICAL BLOOD AND Deoxygenated IVC blood from fetal lower ?

A

Placenta being a venous equilibrator (what’s in venous is also same in arterial) • Placenta’s high O2 consumption rate • Mixture of oxygenated umbilical blood and deoxygenated inferior vena caval blood from fetal lower extremities DUCTUS VENOUS

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58
Q

CO2 is present in many forms in the blood CO2 is present in THE PLACENTA predominantly in the _______form

A

• Dissolved CO2 ~8% • H2CO3carbonic acid • CO3- Carbonate ion • HCO3 (bicarb) ~62% are the predominant forms involved in placental transfer

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59
Q

• Large partial pressure difference

A

between fetal-maternal blood driving transfer

60
Q

• CO2 has a

A

high diffusion capacity; 20X greater than that of O2

61
Q

• Inaccessibility of the placenta and maternal/fetal

A

safety concerns limit direct human studies

62
Q

Data is a one time measurement; influenced by

A

metabolism and changes at delivery

63
Q

• Pharmacokinetic factors

A

(lipid solubitlity, protein/tissue binding, pKa, fetal bld pH, and blood flow) also affect drug transfer

64
Q

Data reported as

A

FETAL to MATERNAL RATIO

65
Q

• Inhalation agents commonly used as maintenance during

A

c-section under GA

66
Q

Halogenated agents have

A

high lipid solubility and low molecular weight facilitating placental transfer; F/M ratios of 0.6-0.9; may see low Apgar scores such as isoflurane

67
Q

• Nitrous also rapidly crosses within

A

3 minutes; may see neonatal depression and diffusion hypoxia can occur; supplemental O2 a must

68
Q

• Lipophyllic nature enhances placental transfer • Thiopental, methohexital, ketamine, propofol, etomidate, diazepam and midazolam have been studied, they are all ______; enhances •will Ketamine affect baby HIGH FM ratio for_____________+ _________

A

All show rapid transfer to fetus with high F/M ratios (> 0.5) and may lower the 1 and 5 minute Apgar scores Lipophillic; Yes , FM is 1.6 crosses placenta Diazepam + midazolam

69
Q

• A mainstay of pain relief in obstetrics

A

OPIOIDS

70
Q

• Epidural/intrathecal administration limits s

A

Systemic levels and fetal transfer; less neonatal depression

71
Q

OPIOIDS SHOULD GO

A

EPIDURAL (Same as IV dose for fentanyl) SPINAL or subarachnoid

72
Q

IV administration of opiods

A

rapid transfer and neonatal cause ventilation depression

73
Q

Demerol used for

A

Shivering Associated with neonatal depression RAPid administration will be 1 in about 2-3 hours

74
Q

LOCAL anesthetics (GOOD) what enhances transfer as far as molecular weight, degree of ionization and lipid solubility What SLOWS protein binding?

A

• Commonly used in labor for analgesia • Route of administration effects maternal blood levels and placental transfer • Low molecular weight, low degree of ionization and high lipid solubility enhance transfer • Protein binding slows transfer; bupivacaine is highly protein bound; lidocaine is less protein bound

75
Q

EPIDURAL REMOVED Epidural and IV dose of fentanyl

A

MOM needs medications Same

76
Q

Requires more volume (Epidural vs spinal) EPIDURAL limits

A

EPIDURAL systemic levels and fetal transfer , less neonatal depression

77
Q

Differentiate : LIDOCAINE vs BUPIVACAINE

A

BUPIVACAINE and lidocaine Bupivacaine is HIGHLY PROTEIN bound and Lidocaine is LOW PROTEIN BOUND Faster onset and offset : Lidocaine BUPIVACAINE –> Last LONGER but slower onset. F/M ratio is low

78
Q

Duramorph to spinal can cause________ monitor for-______

A

APNEA monitor for 24 hours

79
Q

LIke lidocaine

A

MEPIVACAINE

80
Q

• Animal studies have shown neonate

A

Less sensitive to CNS/cardiotoxic effects; felt due to larger volume of distribution

81
Q

• Little direct effect on fetal heart rate; FHR changes Exception : ______Causes less _______

A

most often due to indirect factors such as maternal hypotension or uterine hyperstimulation; exception may be paracervical block (LESS MATERNAL STIMULATION)

82
Q

• Minor transient effects on neurobehavioral tests; other

A

factors more important than choice of LA

83
Q

• Little direct effect on fetal heart rate; FHR changes

A

most often due to indirect factors such as maternal hypotension or uterine hyperstimulation; exception may be para-cervical block

84
Q

Glycopyrrolate does not cross

A

DO NOT CROSS BARRIER Do not affect neonate

85
Q

Fully ionized quaternary ammonium salts

A

• do not readily cross the placenta • rarely effect neonatal muscle tone

86
Q

• Succinylcholine undetectable after single dose

A

• repeated high doses (>300 mg) may cause neonatal muscular block or if neonatal pseudocholinesterase deficiency present

87
Q

• Non-depolarizers F/M is •

A

LOW F/M concentrations may increase over time • little concern during c-section

88
Q

You can do this agent with low F/M

A

Rocuronium in a patient

89
Q

During C-section, surgeon stated abdomen is tight, already given succ or rocc what to do next?

A

Give more gases Hypotension , relaxing too much you’re in trouble too

90
Q

Glycopyrrolate is

A

poorly transferrd low F/M ratio

91
Q

Quarternary ammonium

A

Anticholinesterases NEOSTIGMINE Ionized physiologic pH(limited placental transfer but detectable levels found in umbilical blood) May cause bradycardia.

92
Q

FetaL lungs are

A

STAGNANT (not usef for oxygenation) FLUID FILLED High PAP 70/45 normal 15-20

93
Q

Shunt

A

Foramen ovale (RA to LA) Ductus arteriosus (Pulmonary artery to Aorta) Ductus venosus (in liver, mix with LE and IVC) Placenta

94
Q

Lowest site of SVR

A

Does not completly oxygenate blood Greatest saturation is 70-80% Connected with

95
Q

Fetal renal function

A

Low RBF and Low GFR stagnant organ low SVR High Renal vascular resistane Low Permeability of Glomerular Capillaries Small Size and Number of Glomeruli (things not diffuse easily)

96
Q

Adaptive Alterations•e • Nml 15 g/dL

A

• ↑ 2,3-diphosphoglycerate (2,3-DPG) ↑ Hemoglobin-binding • Less affinity for carbon dioxide

97
Q

Normal hemoglobin inside of womb is

A

15g/dL

98
Q

PaO2

A

30-35

99
Q

Hgb shift to the

A

LEFT relative to adult curve

100
Q

HgF

A

higher affinity of oxygen

101
Q

2,3 DPG produces in

A

Higher concentration in placenta

102
Q

Transitional circulaton

A

first breath–> Fluid filled to air filled , vaginal deliver squeeze fluids and lymphatics drain that fluid

103
Q

What negative pressure must be generated

A

40-60 cm H2O

104
Q

Surface tension

A

surfactant help

105
Q

Within 5-10 min what happen

A

Normal TV Lung expansion

106
Q

When is FRC normalized

A

within 1 hour and stabilized ABG

107
Q

PO2 of 60 = 90 SPO2, For a PO2 of 50

A

about 80

108
Q

With a PO2 of 70

A

about 100 SPO2

109
Q

Know

A

SHUNT, direction of blood flow,

110
Q

Changes at right Ventricle

A

Dcrease afterload Decrease pulmonary vascular resistance DUCTAL CLOSURE Volume decrease ELiminated vein return Output diminished 25%

111
Q

Changes at left Ventricle

A

Increase afterload Placenta ELIMINATE SHOrtly after lungs expand DUCTAL CLOSURE Increase volume output nearly greater than 50% Transient LEFT TO RIGHT SHUNT

112
Q

PLACENTA is a shunt

A

NEED TO DISPLACE OR REMOVE FOR CPR

113
Q

Left ventricle increases performance

A

Catecholamines increase

114
Q

PVR goes from

A

Constriction to dilation RV wall thickness decrease

115
Q

Foramen Olvee

A

Closes due to INCREASE in LVEDP and left atrial pressure

116
Q

Once closes it’s

A

FOSSA OVALIS

117
Q

% percentage with patent FO

A

25-50% of adults

118
Q

Anesthesia considerations

A

Leads to right to left shunt under general anesthesia Significant cause of Persistant arterial despite 100% O2

119
Q

if not enough pressure on the left you can get a

A

RIGHT TO LEFT SHUNT< causing arterial desaturation

120
Q

Considerations for R to LEFT shunt, remove AIR

A

Right atrium, Right ventricle , lungs,

121
Q

Ductus arteriosus becomes

A

Ligamentum arteriosum

122
Q

Increase PO2 encourages

A

Closure

123
Q

Given to patient with no closure

A

PGE1 blocker INDOMETHACIN

124
Q

PDA

A

Failure to thrive Left to right shunt –> Increase PBF –> Volume overload

125
Q

PDA shunt

A

oxygen right blood from aorta to pulmonary artery–> volume overload

126
Q

PDA treatment

A

Depends on size (small one not treated) Lasix Digoxin (Increase Ca2) PDA closure device.

127
Q

Ductus Venous turn into

A

Ligamentum Venosum

128
Q

Ligementum Venousus CLOSES within Functionally Closes

A

Shunts blood from liver to IVC 50% or less Closes within 7 days when infant is born

129
Q

CHANGES at birth Renal GFR ______ mature

A

similar to lung Arterial Pressure Increase Renal vascular resistance Increase GFR 3-4 days 70 % mature 1 month

130
Q

Vicious cycle of persistent fetal circulation

A

Hypoxia/hypercabnia/acidosis/cold –> pulmonary vasoconstriction –> Increase PVR –> R to left shunt (open FO)

131
Q

Persistent Pulmonary Hypertension

A

Elevated PVR to point blood is shunted fetal cardiac channels Systemic arterial hypoxemia

132
Q

Treatment PPH

A

Treatment • Depends on Severity • Surfactant • Ventilation Techniques • Nitric Oxide • ECMO

133
Q

Nitrous Oxide

A

Pulmonary vasculature resistance

134
Q

Uterine blood flow is ________proportional to fetal umbilical venous partial pressure of O2

A

DIRECTLY

135
Q

Venous partial pressure may affected by drugs

A

May increase or decrease resistance in placenta

136
Q

RA to LA shunting is through _______and bring oxygen to

A

Foramen Ovale; Cerebral circulation

137
Q

Spiral arteries will bleed after placenta is removed, body will try to

A

Constrict

138
Q

Mother’s blood into

A

INTERVILLOUS SPACE

139
Q

Baby’s blood into

A

VILLI

140
Q

Connection between Aorta and pulmonary artery

A

Ductus Arteriosus ( DA)

141
Q

Nitrous oxide can make spinal arteries bleeding

A

worse, more vasodilation

142
Q

Does vaginal arteries supply placenta

A

No

143
Q

Placental septum is an

A

invagination of tissue

144
Q

Uterine Blood flow Parallel

A

Placenta BLOOD FLOW

145
Q

High Local _______ concentration lead to diminishes activity of key intracellular enzymes that mediate vasonconstriction

A

ESTROGEN:

146
Q

Identify the FETAL SHUNTS and structure

A

A-Ductus Arteriosus

B- SVC

C- Pulmonary artery

D- Foramen Ovale

E- IVC

F- Ductus Venosus

G- IVC

H- Portal vein

I- UMBILICAL vein

J- UMBILICAL arteries

K - Descending Aorta

L- Pulmonary atery

M- Pulmonary Veins

SNRAObPedGer (25 decks)

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