Maternal Physiology Flashcards
What is the mean weight gain during pregnancy?
17% avg 12 kg
The fetus represents what portion of mean weight gain?
1/3
How does weight gain differ in each trimester?
1st Trimester: 1-2kg (mostly water)2nd & 3rd Trimester: 5-6kg each
What happens to oxygen consumption (VO2) during pregnancy?
Increases approx. 30%
-Predominantly metabolic needs of fetus, uterus, and placenta
Why are pregnant women at an increased risk for epistaxis?
Capillary engorgement of the oropharynx, nasal mucosa, and larynx
What happens to the large airways in pregnant women and what effect does it have on airway conductance?
Dilation of large airways increases airway conductance
What anatomical changes are seen in regards to respiration?
Elevated position of diaphragm
Thoracic cage increases 5 - 7 cm
Vertical measurement of chest decreases 4 cm
What happens to blood volume during pregnancy?
Increases from 60-65 mL/kg to 90 mL/kg
When is blood volume highest during pregnancy?
During the third trimester
What happens to cardiac output during pregnancy?
Increases 40%
When is cardiac output highest for pregnant women?
Immediately postpartum
What effect does term gestation have on stroke volume and heart rate?
Stroke Volume: +30%
Heart Rate: +15-30%
What effect does term gestation have on SVR and PVR?
SVR: -20%PVR: -30%
How do the fetal and parturient oxyhemoglobin dissociation curves compared to a normal curve.
Fetal = L shift (greater binding affinity) P50 = 19 Parturient = R shift P50 = 30
What happens to uterine bloodflow at term gestation?
Increases from 50 mL/min to 600-700 mL/min(80% of increase to placenta)
How is uterine bloodflow regulated?
PRESSURE DEPENDENTNOT Auto-regulated
What happens to renal plasma flow during gestation?
Increases-Highest at 26 weeks (+85%)
What happens to skin bloodflow term gestation?
Increases 3-4x nonpregnant flow
What happens to systolic and diastolic blood pressures at term gestation?
Systolic: - 6-8%
Diastolic: - 20-25% early (normal at term)
What is caval compression and when does it begin?
Complete or partial obstruction of the interior vena cava
- decreasing venous return(25-40% CO decrease)
- Begins at 13 to 16 weeks
How is caval compression alleviated?
Left uterine displacement
What happens to tidal volume and FRC at term gestation?
Tidal Volume: +40%FRC: -20%
What effect does time gestation have on respiratory rate and ventilation?
RR: +0-15%
Minute and Alveolar Ventilation: +40%
What effects do the respiratory changes of the parturient have on the anesthetic plan?
Increased VO2 and decreased FRC lead to faster desaturation