Maternal Physiology Flashcards

1
Q

What is the mean weight gain during pregnancy?

A

17% avg 12 kg

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2
Q

The fetus represents what portion of mean weight gain?

A

1/3

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3
Q

How does weight gain differ in each trimester?

A

1st Trimester: 1-2kg (mostly water)2nd & 3rd Trimester: 5-6kg each

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4
Q

What happens to oxygen consumption (VO2) during pregnancy?

A

Increases approx. 30%

-Predominantly metabolic needs of fetus, uterus, and placenta

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5
Q

Why are pregnant women at an increased risk for epistaxis?

A

Capillary engorgement of the oropharynx, nasal mucosa, and larynx

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6
Q

What happens to the large airways in pregnant women and what effect does it have on airway conductance?

A

Dilation of large airways increases airway conductance

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7
Q

What anatomical changes are seen in regards to respiration?

A

Elevated position of diaphragm
Thoracic cage increases 5 - 7 cm
Vertical measurement of chest decreases 4 cm

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8
Q

What happens to blood volume during pregnancy?

A

Increases from 60-65 mL/kg to 90 mL/kg

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9
Q

When is blood volume highest during pregnancy?

A

During the third trimester

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10
Q

What happens to cardiac output during pregnancy?

A

Increases 40%

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11
Q

When is cardiac output highest for pregnant women?

A

Immediately postpartum

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12
Q

What effect does term gestation have on stroke volume and heart rate?

A

Stroke Volume: +30%

Heart Rate: +15-30%

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13
Q

What effect does term gestation have on SVR and PVR?

A

SVR: -20%PVR: -30%

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14
Q

How do the fetal and parturient oxyhemoglobin dissociation curves compared to a normal curve.

A
Fetal = L shift (greater binding affinity) P50 = 19
Parturient = R shift P50 = 30
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15
Q

What happens to uterine bloodflow at term gestation?

A

Increases from 50 mL/min to 600-700 mL/min(80% of increase to placenta)

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16
Q

How is uterine bloodflow regulated?

A

PRESSURE DEPENDENTNOT Auto-regulated

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17
Q

What happens to renal plasma flow during gestation?

A

Increases-Highest at 26 weeks (+85%)

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18
Q

What happens to skin bloodflow term gestation?

A

Increases 3-4x nonpregnant flow

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19
Q

What happens to systolic and diastolic blood pressures at term gestation?

A

Systolic: - 6-8%
Diastolic: - 20-25% early (normal at term)

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20
Q

What is caval compression and when does it begin?

A

Complete or partial obstruction of the interior vena cava

  • decreasing venous return(25-40% CO decrease)
  • Begins at 13 to 16 weeks
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21
Q

How is caval compression alleviated?

A

Left uterine displacement

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22
Q

What happens to tidal volume and FRC at term gestation?

A

Tidal Volume: +40%FRC: -20%

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23
Q

What effect does time gestation have on respiratory rate and ventilation?

A

RR: +0-15%

Minute and Alveolar Ventilation: +40%

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24
Q

What effects do the respiratory changes of the parturient have on the anesthetic plan?

A

Increased VO2 and decreased FRC lead to faster desaturation

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25
Q

What effect does pregnancy have on MAC requirements?

A

Decreases progressively up to 40%

26
Q

What effect does pregnancy have on the CNS?

A

Progesterone mediated CNS depression

27
Q

What affects this pregnancy have on the liver?

A

Hepatic function and blood flow remain largely unchanged

28
Q

What effect does pregnancy have on colloid osmotic pressure?

A

Decreases by 5 mmHg at term

29
Q

Describe the effects of pregnancy on coagulation

A

Accelerated, compensated coagulation–Enhanced platelet turnover, clotting, fibrinolysis
PT & PTT: -20%
Bleeding time: -10%

30
Q

What sort of endocrine changes can be seen in the pregnant patient?

A
  • Thyroid hypertrophy
  • Parathyroid and Ca2+ changes (important for fetus)
  • Insulin resistance (degree varies)
31
Q

What sorts of GI changes are seen in the parturient? Why are these important?

A
Delayed gastric emptying
Increased gastric volume
Decreased gastric pH
Decreased GI mobility** 
Increased aspiration risk **
32
Q

Pregnancy predisposes women what to GI disturbances?

A

GERDEsophagitisGallstone formation

33
Q

At term, pregnant women require more or less local anesthetics?

A

Local anesthetic requirement reduced up to 30%

34
Q

What is the average fetal oxygen consumption at term?

A

21 mL/min

35
Q

Transfer of oxygen to the placenta is dependent upon what two factors?

A

Ratio of maternal uterine bloodflow to fetal umbilical bloodflow

36
Q

20% of women at term develop supine hypotension syndrome. How is it characterized?

A

Hypotension associated with pallor, sweating, or N/V

37
Q

Describe the 3 stages of labor

A

Stage 1: Onset of true labor and ends with complete cervical dilation
Stage 2: Full cervical dilation -> fetal descent -> delivery of fetus
Stage 3: Delivery of placenta

38
Q

The first stage of labor is divided into the latent and active phase. How are these phases characterized?

A

Latent Phase: Water breaks, progressive cervical effacement and minor dilation (2-4cm)
Active Phase: Increased frequency of contractions and cervical dilation (up to 10 cm)

39
Q

What effect does labor have on minute ventilation and oxygen consumption?

A

MV increases up to 300%

VO2 increases 60% above third trimester values

40
Q

At what point during labor and delivery is there the greatest strain on the heart?

A

Immediately after delivery-increases cardiac output as much as 80% above prelabor values

41
Q

How do contractions place an additional burden on the heart?

A

-300-500mL blood displaced from uterus -> central circulation with each contraction

42
Q

What effects do inhalational agents and N2O have on uterine activity and labor?

A

Volatile anesthetics depress uterine activity equally at equipotent doses and cause dose-dependent uterine relaxation.
-Effects minor at low doses
-High doses can result in uterine acne and increased blood loss at delivery
N2O has minimal if any effects

43
Q

What effects do opioids have on the progression of labor? Do they have any effects on the fetus?

A

Minimally decreased the progression of labor
Opiates readily cross the placenta, but effects on neonates at delivery very considerably. (Can cause respiratory depression)

44
Q

Why is Oxytocin (Pitocin) used?

A

Used to induce or augment uterine contractions or to maintain uterine tone postpartumNB: Administer slowly to prevent transient systemic hypotension and reflex tachycardia

45
Q

Why is Methergine used?

A

Methergine causes intense and prolonged uterine contractions.
Given only after delivery to treat uterine atony.
-Usually administered IM because it can cause severe hypertension

46
Q

Why is Hemabate used?

A

Stimulates uterine contractions.
Used to treat refractory postpartum hemorrhage.
Given IM with side effects of N/V & diarrhea

47
Q

Why is magnesium used?

A

Stops premature labor
Prevent eclamptic seizures
Therapeutic serum level = 6-8 mg/dL (Hypotension, heart block, sedation)

48
Q

What is PIH and how is it defined?

A

Pregnancy induced hypertension (preeclampsia)
-Systolic >140 mmHg & Diastolic >90 mmHg (OR as a consistent increase pressure 20% above the patient’s baseline)-Proteinuria (>300mg/day)-Edema

49
Q

What is eclampsia?

A

Preeclampsia with seizures (basically) “Occurrence of generalized tonic-clonic seizures in a pregnant patient with proteinuric hypertension”

50
Q

What is HELLP syndrome?

A

Hemolysis Elevated Liver enzymesLow Platelets

51
Q

What is thought to be the cause of preeclampsia and what is the definitive treatment for it?

A

Cause: abnormal placentation outs out vasoactive substances Only Definitive Cure: Deliver fetus and placenta

52
Q

What differential diagnosis must be ruled out in the case of eclampsia?

A

Amniotic Fluid embolism

53
Q

True or False: Complications of PIH are limited only to the cardiovascular system

A

FALSE

Complications of PIH include cardiovascular, pulmonary, neurological, hepatic, renal, and hematological

54
Q

Acute fatty liver of pregnancy is seen during which trimester?What are the symptoms and mortality rate?

A

Rare3rd Trimester High Mortality rateSymptoms: Jaundice, N/V, epigastric pain, increased liver enzymes, decreased serum glucose

55
Q

What is an amniotic fluid embolism?

A

Sometimes called “anaphylactoid syndrome of pregnancy” Presents when mother’s circulation is exposed to amniotic fluid.

56
Q

How does amniotic fluid embolism present and what is the mortality rate?

A

Patients typically present with sudden tachypnea, cyanosis, shock, and generalized bleeding –> respiratory distress & CV collapse
-acute PE, DIC, & uterine atony = majot pathophysiological manifestations responsible
86% Mortality (>50% in 1st hour)-usually diagnosed post-mortem

57
Q

What is DIC?

A

Disseminated intravascular coagulation-Characterized by widespread systemic activation of coagulation, resulting in intravascular formation of fibrin and ultimately thrombotic formation occlusion of small and midsized vessels

58
Q

Why are pregnant women at increased risk for thromboembolic disease?What else can increase this risk?

A

-increase in most clotting factors
-Gravid uterus causes venous stasis
Other risks:
-smoking, obesity, old age, genetics

59
Q

Pregnant patients with pre-existing renal disease are at an increased risk for what pregnancy induced disease state?

A

Preeclampsia

60
Q

What are some of the major concerns for inducing general anesthesia in a pregnant patient?

A

SECURING AIRWAY

  • desat faster
  • increased aspiration risk
  • VC harder to visualize due to altered anatomy
61
Q

Extrauterine life is not possible until what point of Gestation?

A

After 24-25 weeks (formation of pulmonary capillaries)