8 Doppler Flashcards
What is Doppler assessing?
fetal and maternal circulation
Doppler uses ___ and ___ assessment for flow patterns and measurements and referenced to gestational age
Qualitative - Not measured loss D flow, reversal, notching
and Quantitative
Methods
- CW (non stress test)
- PW (velocities that produce F shifts < 1/2 PRF)
- Color - to locate, direction, MCA on C of W
- Power - when direction not needed, pick up very small vessels
Most fetal blood investigated is less than
1m/sec
so we are successful with PW
Doppler can cause____. Color doppler adds little extra energy where PW adds alot (Dr. Zwiebel)
Bioeffects
Diastolic velocities ____ as term approaches due to ____placental resistance (larger placenta vessels)
Increases; decreased
Semiquantitative Analysis is used because it is
angle independent*
bc it is difficult to control angle of incidence
What is PI (pulsatility index)
PI= S-D/mean velocity
What is RI (resistive index)
RI= S-D/S
What is the fav Ratio outcome we use now and why?
PI because it will continue to show change (have value) even when diastolic flow is zero
Unlike RI when D flow 0 RI =1
As impedance increases the pulsatility of flow velocity ______?
increases
How many waveforms should be measured and averaged to avoid error?
- (need this)
3 Factors that will affect outcome blood flow in diastole for measurement
Tachycardia and Bradycardia
Fetal breathing.
AVOID DOPPLER DURING FETAL BREATHING. (too many different PSV)
During embryonic period normal to have ___ resistance flow with ____ end diastolic flow
HIGH; ABSENT
Towards end of 1st Trimester end diastolic flow____
appears
small vessel
As pregnancy progresses the end diastolic velocity ____.
Increases
due to vessel enlargement
THE easiest vessel to. asses is the?
Umbilical artery (2 arteries in the cord, 1 is the vein=maternal)
Umbilical arteries are____
pulsatile
bc fetal heart pumping blood back into the placenta
Next most common vessel is the ?
MCA prox to transducer
Third most common
Ductus Venousus
Other vessels assessed
Umbilical vein
Fetal aorta - rare
Fetal IVC - rare
What does the PI, RU and S/D ratio do with increasing gestational age?
decreases because the diastolic flow is increasing
Ratios are higher if measured at the ___ ___ of the cord
fetal end
It is recommended to measure ____ cord
mid
With twins measure the fetal artery just outside the ____ ___ so you don’t mix them up
fetal abdomen
Abnormal findings is decreased or absent diastolic flow causing increased RI & PI In the _______ artery
umbilical
_____ of ______flow in the umbilical artery is severe can cause death (too much pressure on fetal heart)
Reversed; diastolic
RI >___ is abnormal from ___weeks onward
- 72 ; 26 weeks
* must use gestational age when reference a value
Indications for doing doppler
Small for gestational age IUGR need umbilical artery doppler Mom have HTN IDDM (mom type 1, prior too) TTTS (monochoionic, 1 donor, 1 receipt) poor growth in both twins due to placental insuff.
Umbilical ARTERY Doppler Normally = Forward flow through ___ phases of the cardiac cycle
ALL
Umbilical ARTERY Absent ______flow is ABNORMAL and means the blood is stoping when the babies heart is relaxing. As well as _____ flow, opposite direction, severe destress.
Diastolic; reversed
With the fetal aorta you are sampling the ?
descending aorta, just about diaphragm
Appearance of the aorta is similar to the ____ artery but changes are noticed in aorta 1st. Decreased, absent or reversed diastolic flow same indications.
umbilical
What artery is used to assess brain sparing with IUGR fetuses?
MCA