Hypoxemia Correct Answer: Decreased oxygen in blood
Hypoxia Correct Answer: Not enough oxygen to supply organs
Normal fetal PO2 Correct Answer: 15-25 mmhm
What factors can change the maternal HR? Correct Answer: Intrinsic pacemakers (SA & AV
node)
Cardiac conduction system
Autonomic regulation... Sympathetic, parasympathetic
Humoral factors (catecholamines)
Extrinsic factors (medications)
Local factors (Ca, K)
What are the 3 most common causes of decrease cardiac output in the OB patient? Correct
Answer: Reduced preload (HypoTN) from
-hypovolemia
-compression of inferior vena cava
-anesthesia
In what area of the placenta does exchange of gases, nutrients, waste, hormones, antibodies &
medications occur? Correct Answer: Maternal blood in the intervillous space
and fetal blood in the villous capillaries
These are separated by the blood-blood barrier
Oxygen, CO2, NaCl, lipids, vitamins and some drugs are exchanged by... Correct Answer:
Simple diffusion
Glucose & carbohydrates are exchanged by... Correct Answer: Facilitated diffusion
Amino acids, water-soluble vitamins & large ions are transported by... Correct Answer: Active
transport
What conditions decrease the volume of the blood in the intervillous space? Correct Answer:
Abruption
Infarction
Thrombosis
Infection
...These can also decrease the surface area of the chorionic villous thus decreasing O2 absorption
(less surface area = less absorption)
Diffusion across the blood-blood barrier is inversely proportional to _ Correct Answer:
Distance. Greater distance = less diffusion
Villous hemorrhage, thrombosis, infarction, deems, fibrosis...can increase distance
,What could result from trauma that causes damages chorionic vessels? Correct Answer:
Maternal-fetal hemorrhage!
Ruptured vasa previa Correct Answer: Vasa previa is a placental vessels that crosses the
chorionic membrane and is close to the cervical os. It can be damaged from just a cervical exam
or cervical check!
What 3 shunts/mechanisms direct oxygenated blood to vital organs in the fetus? Correct Answer:
Ductus venous, foramen ovale, ductus arteriosus
When fetus is born, what changes are responsible for the fetus's transition to neonate life?
Correct Answer: Umbilical-placental circulation is eliminated
Clamping of umbilical cord eliminates umbilica.-placental circulation and raises the BP in
neonate's aorta
Flow across ductus arteriosus is reversed
Catecholamines release increases BP & HR
Expansion of neonate's lungs occurs
The fetal circulation is designed to send oxygenated blood primarily to what 3 organs in the
fetus? Correct Answer: brain, heart, adrenal gland
Which ventricle is dominant in the fetal heart? Correct Answer: Right ventricle
Because fetal circulation works in parallel rather than in series like adult circulation
Umbilical vein - type of blood it carries & where? Correct Answer: Carries oxygenated blood
from placenta to fetus
Compression of umbilical vein Correct Answer: Can cause acceleration, sometimes before a
variable or prolonged accelerations
Umbilical artery Correct Answer: Carries deoxygenated blood from fetus to placenta
Compression of umbilical artery Correct Answer: Variable
Oxygen depletion cascade Correct Answer: aerobic metabolism
>hypoxemia
>tissue hypoxia
>anaerobic metabolism
>lactic acid build up
>metabolic acidosis
CO = HR x SV for a fetus Correct Answer: Cardiac output for a fetus is only related to their
heart rate, not their stroke volume. a fetus cannot regulate their stroke volume, only their heart
rate
,Aerobic metabolism Correct Answer: O2 > ATP > by products are CO2 & H2O
Hypoxia can lead to what time of metabolism? Correct Answer: Anaerobic metabolism... by
product = lactic acid
Sustained hypoxia > sustained anaerobic metabolism with by product of lactic acid leads to _
Correct Answer: Metabolic acidosis
Metabolic acidosis Correct Answer: Accumulation of lactic acid in the body (Low pH)
The body then tries to use buffer bases (bicarbonate) to help increase the pH to a more
basic/neutral level
Eventually the buffering capacity is exceeded and the pH is low and cannot be raised to a normal
level
Sustained metabolic acidosis leads to _ Correct Answer: Metabolic acidemia
When the body cannot raise the pH to a normal level with buffering bases, sustained low pH
What will sustained hypoxia & metabolic acidosis lead to? Correct Answer: Loss of peripheral
vascular smooth muscle contraction, which decreases peripheral vascular resistance
>>>>> Leads to Fetal Hypotension
>>>>>>>>>>Hypoxic injuries to fetal heart & brain
Distinguish between metabolic & respiratory academia Correct Answer: Metabolic acidemia is ^
lactic acid
Respiratory academia is ^ CO2
Causes of respiratory acidemia Correct Answer: increased CO2
cord compression/true knot
-can develop rapidly and can correct rapidly
Intermittent Auscultation done with 4 devices Correct Answer: Stethoscope
Fetoscope
Doppler US
TVUS - Transvaginal US
Stethoscope for IA Correct Answer: Dome on maternal abdomen over fetal back
Fetoscope Correct Answer: Worn on listener's head
Bone conduction for HR
A reliable method for confirming presence of irregular HR
Doppler US Correct Answer: Transmits ultra high-frequency sound waves to the moving
interface of the fetal heart valves, this is deflected back to US
Transvaginal US Correct Answer: 2 dimensional video using M-wave imaging
, Procedure for Intermittent Auscultation Correct Answer: 1. Leopold's
2. Gel, devices on fetal back
3. Count maternal radial pulse
4. Palpate ctxs so that you can count the FHR between contractions
5. Count FHR 30-60 seconds after ctxs
6. Auscultate before, during & after ctx
7. If HR discrepancies then auscultate for longer, consider need for EFM
Leopold's maneuver Correct Answer: Before Leopold's: empty bladder, knees flexed, towel
under right hip to prevent supine hypoTN
1. Fundus
2. Fetal back / Fetal parts
3. Over true pelvis inlet
head not engaged > Pallach's maneuver
Pallach's maneuver Correct Answer: If head is not engaged use this maneuver to determine if
head is flexed or extended
-Cephalic prominence on side with small parts = vertex
-Cephalic prominence on side with back = face is presenting
Intermittent Auscultation Category 1 Correct Answer: FHR BL 110-160
Regular Rhythm
Presence or absence of increases in FHR above baseline
-Indicates normal fetal acid-base balance
Intermittent Auscultation Category 2 Correct Answer: Includes everything not classified in
category 1
Interventions: Increase frequency of IA, intrauterine resuscitations, EFM, notify provider
Another name for EFM Correct Answer: Cadiotocography
Internal vs External FHR monitoring Correct Answer: US - high frequency sound waves
detected that reflect mechanical action of fetal heart
FSE - measures heart's electrical activity. Electrode converts fetal electrocardiogram to FHR ia
carditachometer by measuring consecutive R-R intervals.
-Electrode penetrates presenting fetal part about 1.5 mm
When using a doppler US, what does "autocorrelation" do? Correct Answer: compares
successive reflective waveforms at many points
Internal vs External uterine activity monitoring Correct Answer: Toco - external pressure
sensing device/detects uterine wall shape
IUPC - catheter compressed during contraction > pressure on transducer tip > converts pressure
to mmHG
Cartesian graph Correct Answer: The graph the FHR is charted on