Class 1 Maternal and Fetal Physiology Flashcards
5 neurological changes with pregnancy.
- ↓ MAC
- ↓ epidural space
- ↓ CSF
- ↑ sensitivity to LA
- epidural vein engorge
With pregnancy there is a net increase in ventilation, what 3 things contribute to that?
- ↑ Minute ventilation
- ↑ Tidal volume
- ↑ RR
Increase in ventilation causes ________ to decrease and can lead to _________ _________
- PaCO2
- Respiratory Alkalosis
What compensates for the respiratory alkalosis found in pregnant women?
-Metabolic acidosis by excreting bicarb
The _______ displaces the _______ and decreases _______ by _____%.
- Uterus
- Diaphragm
- FRC
- 20%
What 2 things lead to maternal hypoxia during induction?
- ↓ FRC
- ↑ Maternal O2 consumption
________ is mandatory prior to induction!!!
Preoxygenation
What mechanisms aids in the delivery of O2 to the fetus?
-P50 hemoglobin increase from 27-30
Should you use a smaller or larger ETT and why?
- Smaller
- Mucosal venous engorgement / edema
_________ scores increase throughout labor.
Mallampati
What causes hypervolemia and anemia during pregnancy?
-Increase in plasma volume (45%) that is greater than the increase in RBC (20%)
How O2 delivery optimized during pregnancy?
- Increase in CO
- Right shift of oxyhemo curve
What causes the 40% increase in CO?
Increase in HR and Stroke volume
Peripheral vascular resistance drops by 15% why?
-Progesterone relaxes venous smooth muscle
Response to adrenergic drugs is _______
Blunted
________ _________ can be seen on CXR
Cardiac hypertrophy
________ ________ are often present on auscultation
heart murmurs
________ in plasma osmotic pressure
Decline
What 5 things can be seen when a prego lies flat?
- Hypotension
- Pallor
- Nausea
- Vomiting
- Diaphoresis
How early can supine hypotension be seen?
20 weeks
Pregos are at a hypercoagulable state witch puts them at a greater risk of what?
-PE
BUN and Creatinine are ______ reduced.
Mildly
Renal blood flow and GFR are _______ by ______
Increased
50%
What 2 things decrease gastroesopheagal sphincter tone?
- Stomach displacement by uterus
- Progesterone
What increase acid secretion in pregos?
-Placental gastrin
Pregos are at a greater risk for aspiration why?
- > 25 cc of gastric fluid
- pH less than 2.5
A 20% decrease in pseudocholinesterase does not affect succs length, why?
-Due to a simultaneous increase in volume of distribution.
Why are pregos more susceptible to gallstones?
-Decreased CCK and contractile response
What leads to higher fetal glucose transfer?
- Maternal insulin resistance
- Higher plasma glucose levels
What 5 ways do agents cross the placenta?
- Diffusion
- Bulk flow
- Active transport
- Pinocytosis
- Breaks
What is oxygen transfer dependent on?
-Maternal uterine flow vs. fetal umbilical flow
What has the smallest storage to utilization ratio in the fetus?
–Oxygen (42 ml stored, 21 ml/min consumption)
How long can a fetus survive w/ O2 deprivation?
-10 minutes
What 2 compensatory mechanisms are present during O2 deprivation?
- Redistribution
- Anaerobic metabolism
How are the Oxyhemo curves of the fetus and mother shifted and why?
- Fetus to the left
- Maternal to the right
- Allows for transfer of O2 from mother to fetus
Placental blood has a PaO2 of what?
-40 mmHg
Fetal hemaglobin is _______ than maternal hemaglobin.
Higher
Who’s Hgb has a lower affinity for CO2, mom or fetus?
Fetus
How does CO2 cross into the placenta?
Simple diffusion
Uterine blood flow represents ______ of CO at about _______ ml per minute?
10%
-600-700 mls/min
What is non pregnant uterine blood flow?
50 mls/min
Where does uterine blood flow go?
- 80% placenta
- 20% myometrium
Name the 3 factors that influence uterine blood flow.
- Systemic BP
- Uterine vasoconstriction
- Uterine Contractions
How does propofol effect UBF?
-Mild reduction via maternal hypotension
At what dose will Ketamine effect UBF.
->1.5 mg/kg
Volatile agents effect on UBF?
- Decrease via hypotension
- Less than 1 MAC has minor effects
______ and ______ have little effects on UBF
- Nitrous
- Opioids
High serum LA can result in what?
-Uterine vasoconstriction
Uterine blood flow may _______ with neuriaxial analgesia due to a reduction in maternal __________ levels that ________ vasoconstriction as long as _______ is normal
- Improve
- Catecholamines
- Reduces
- Blood pressure
What does filing the babies lungs with O2 do?
-Decreases pulmonary vascular resistance
Increased pulmonary blood flow increases ______ volume and closes the ________.
- Left ventricle
- Foramen ovale
What closes the ductus?
-Increase O2 tension
What will hypoxia or acidosis do?
Increase R to L shunting through ductus
When does normal labor start?
-40 weeks +/- 2 weeks after LMP
What stage of labor is from onset of true labor until complete dilation?
1st stage
Name the 2 phases of 1st stage?
- Latent = dilation 2-4 cm
- Active = Dilation to 10 cm w/ regular contractions
Describe the 2nd stage of labor
-Complete dilation till infant delivered
What is 3rd stage of labor?
-Time from delivery of infant to placenta delivery
