Maternal Physiology pt1 (Exam2) Flashcards
A term gestation is how many weeks?
- 37-40 weeks
- 3 trimesters
below 37 weeks is considered preterm
Parturient refers to what?
one who is pregnant/in labor
Gravida refers to what?
Number of pregnancies (not babies)
Para refers to what?
number of births >20 weeks
(including still born deliveries at >20weeks)
What is G0P0?
Nulligravida/Nulliparous
- No pregnancies
- No births
What would G1P0 refer to?
Primigravida/nulliparous
- pregnant but not given birth yet
could also have had miscarriage <20 weeks
What would G3P2 refer to?
Multigravida/ Multiparous
- 3 pregnancies (2 births/1 miscarriage)
- 2 births
What is the minimum expected weight gain during pregnancy? What are the components that account for this weight gain?
12 kg (~26 lbs) minimum weight gain:
- Uterus = 1 kg
- Amniotic Fluid = 1kg
- Fetal/Placental Weight = 4kg
- New Fat/Protein stores = 4kg
- Blood volume increase = 2kg
Describe the impact BMI has on total weight gain and rate of weight gain during pregnancy?
How much does total blood volume increase during pregnancy? What are some common symptoms exhibited secondary to this change?
30 - 35% increase
Increased blood volume is responsible for bloating and fluid retention (swelling)
When does the increase in total blood volume of the typical pregnant woman occur?
8 - 32 weeks (Majority of increase by 24 weeks)
Blood volume increases with pregnancy are a result of an increases in which specific blood volumes? What is a hematologic consequence of this change?
Plasma volume and RBC volume increase
plasma volume increases more than RBC volume.
Dilutional anemia (usually not significant)
Why does blood volume increase during pregnancy?
To counteract delivery blood loss
What is the typical expected blood loss with a vaginal delivery and for a C-section?
- Vaginal: ~500 mL
- C-section: ~800 mL
Approximately when does maternal blood volume return to normal post-delivery?
typically back to prepregnancy levels within 6 weeks postpartum
Compare the blood volume of a pregnant patient and a non-pregnant patient in mL/kg.
Non-pregnant female = ~65mL/kg
Pregnant = ~85-90 mL/kg
CO will typically increase by ___% by term.
~40%
In regards to hemodynamics, by 6 weeks there will be an increase in maternal _____ ____ and by 8 - 10 weeks there will be an increase in _____ _____.
6 weeks: ↑ Heart Rate
8-10 weeks: ↑ Stroke Volume
What is the mechanism for increased Stroke Volume in the pregnant patient?
↑ Plasma Renin ⇒ ↑aldosterone ⇒ ↑Na⁺ reabsorption ⇒ ↑water retention ⇒ ↑ Plasma volume ⇒ ↑ Preload ⇒ ↑ SV & ↑CO
How much does uterine blood flow increase during pregancy?
10-20x increase in UBF
- Baseline = ~50 mL/min
- Term = ~700 mL/min
What is the cause of the pregnancy symptoms of warm skin, flushing, and itching?
3-4x increase in skin blood flow
What changes in SVR occur in pregnancy? Why?
- 20% lower than pre-pregnant values due to massive maternal vasodilation
What hormones are responsible for maternal vasodilation?
“PREP”
- Progesterone
- Relaxin
- Estrogen
- Prostacyclin
Pregnancy is a ____ flow, _____ resistance state.
High flow : low resistance
- maternal vasodilation
-
low resistance placental circulation
-uterine vascular bed has low resistance secondary to massive vasodilation (increasing placental flow) - decreased renal vasculature resistance
Do the following increase or decrease during pregnancy?
- Blood volume
- Cardiac Output
- SVR
- ↑ Blood volume (↑ preload)
- ↑ Cardiac Output (↑HR/↑SV)
- ↓ SVR (↓ afterload)
What changes are seen in a maternal heart due to pregnancy? Why does this change occur?
Eccentric Hypertrophy (as much as 50% increase in LV mass)
Occurs to accommodate for increased blood volume and preload.
How does the heart shift due to pregnancy?
Why does this occur?
- Heart shifts anterior and leftward due to diaphragmatic elevation.
Shifting of the heart with pregnancy may lead to what changes on a CXR?
may cause the heart to appear enlarged on a CXR (anterior and leftward shift)
Where does the point of maximal impulse for auscultation shift in a pregnant patient?
- Shifts up and to the left
- 4th ICS mid-clavicular line (normally 5th ICS mid-clavicular line)
What EKG changes are seen in a pregnant patient?
- Left QRS Axis shift in 3rd trimester
- Lead III T-wave inversion
- PR interval shortened (d/t ↑ SNS activity in 3rd trimester/accelerated AV node conduction velocity)
- ST segment depression
- QT interval increased (often still WNL)
With a leftward axis deviation, what QRS charges would you expect to see in leads:
* I
* II
* III
* aVL
* aVF
- I: Positive
- II: Negative
- III: Negative
- aVL: Positive
- aVF: Negative
What are the most common EKG abnormalities in pregnant patients?? How may these EKG changes present to the patient?
Tachydysrhythmias
-(Sinus tach, PAC, PVC)
Pt may experience “palpitations, heart pounding/racing” etc.
What are typically the causes of tachydysrhythmias commonly seen in pregnant patients?
- change in cardiac ion channel conduction
- increased cardiac size
- changes in autonomic tone
- hormones
What cardio valvular changes are typical of pregnancy? Why?
- Tricuspid & Pulmonic regurgitation (>90% of pts)
- Mitral regurgitation (~25-30% of pts)
- typically from extra fluid characteristic in parturients
These typically reverse postpartum.
What heart sound is often heard in the 3rd trimester?
What causes this?
S3/third heart sound: Ventricular Gallop
Due to large volume of blood rushing into highly compliant left ventricle.
What heart sound disappears at term? What is the cause of this sound?
4th heart sound (low pitched sound)
-caused by late diastolic filling of ventricle d/t atrial contraction
What murmur can occur due to cardiac enlargement?
Where is this best heard?
- Grade II SEM (systolic ejection murmur)
- Heard right side of heart, near sternal border
What are the hemodynamic consequences of lying in the supine position during pregnancy? What is the mechanism behind this change and when does this begin to occur?
Aortocaval compression
Gravid Uterus compresses inferior vena cava and aorta.
Occurs as early as 13-16 weeks.
What factor exacerbates aortocaval compression?
Anesthesia due to vasodilation
What are the s/s of aortocaval compression?
- Fetal Distress
- Tachycardia (initially) → bradycardia (if compression persists)
- N/V
- Pallor
- Loss of consciousness
What is the treatment for aortocaval compression?
LUD (Left Uterine Displacement)
- displaces uterus off of vena cava and aorta
- Done by tilting the patient to the left
