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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_5817_Библиотеки_им_академика_М_И_Перельмана-1.pdf
Blood Flow Analysis During Pregnancy
1
β-blockers
왘 The antiadrenergic substances labetalol and meto-
prolol had no effect on intervillous or umbilical
blood flow. Metoprolol, however, raised the aortic
RI and lowered the heart rate in the fetus. No such
effect could be demonstrated with labetalol (Jouppila et al. 1986, Jouppila and Kirkinen 1986).
왘 These results do not completely match those of
another study that used the PI in the umbilical aa. as
a basis for evaluation. When the initial values were
normal, no changes were seen with hydralazine, but
there was a rise after labetalol in 3 out of 11 cases.
When the PI was initially increased, flow tended to
improve when hydralazine was used, while with
labetalol a significant rise was noted in five out of
seven cases. In three fetuses flow velocity even became negative (Harper and Murnaghan 1986b).
왘 Atenolol, a selective β
uteroplacental vascular bed and in the fetal aorta,
while flow volume remained constant in the aorta
and the umbilical v. (Montan et al. 1987).
-blocker, raised the PI in the
1
Calcium Antagonists
왘 While isradipin lowers the maternal blood pressure,
it has no effect on uteroplacental or fetoplacental
hemodynamics (Lunell et al. 1991).
왘 Nifedipin has no effect on the Doppler sonograms of
the uteroplacental or fetoplacental vessels (Duggan
et al. 1993).
Intrapartum pain relief by epidural analgesia induces
a reduced flow resistance in the uteroplacental aa., and
this can also be demonstrated in the umbilical aa.
(Giles et al. 1987; Marx et al. 1986). The basis for this
effect may be a reduction in catecholamine-induced
resistance in the fetoplacental vascular bed. Fetal blood
flow in the aorta and the umbilical v. undergoes no
quantitativechanges, while the mean flow velocity and
the vascular diameter are unchanged (Lindblad et al.
1984, 1987).
64
Epidural Anesthesia
No changes were observed in the flow curves of the
uteroplacental or the fetoplacental vessels when
bupivacaine with or without epinephrine was used for
epidural anesthesia, as long as the maternal circulation
remained stable (Alahuhta et al. 1991a, 1991b). Modification with sufentanil similarly had no demonstrable
effect on the waveform indices of the uteroplacental
and fetoplacental beds (Alahuhta et al. 1993). It only
limited the amplitude of the oscillations.
Even when significant changes in the maternal
circulatory parameters were noted, there was no
change in either uteroplacental or fetoplacental blood
flow (Patton et al. 1991).
When there were preexisting changes in the
waveform of the uteroplacental vessels due to pree-
clampsia, epidural anesthesia normalized the S/D ratio,
while the umbilical aa. remained hemodynamically
constant (Ramos et al. 1991).
The PI in the uteroplacental aa. rises significantly
during hypotension due to epidural anesthesia. The administration of ephedrine or methoxamine does not
normalize flow parameters in the long term.
5 Documentation
In contrast to examinations such as magnetic resonance imaging (MRI), ultrasound examinations cannot
be documented objectively and reproducibly, since the
scan plane is not recorded.
Probably the best documentation of a dynamic examination is video recording. A disadvantage of such a
procedure would be the costly storage needed to allow
rapid retrieval of previous records. Alternatively, all
findings could be recorded using a video printer. Besides patient data and the date of examination the
printout should include all readings and, if appropriate, comments. Similarly notes on the area examined and, if appropriate, the selected plane should
be incorporated. The instrument provides suggested
symbols for this purpose. The advantage of this documentation system lies in its speed. However, a considerable disadvantage is that the prints are unstable
when exposed to light. Hence the digital storage of ultrasound findings, for example, on optical disks, is becoming increasingly popular. This ensures not only
safe storage of the records over time, but also guards
the findings against subsequent alterations.
Selecting images to be documented is a major problem. While abnormal findings should always be documented, selecting representative normal records for
documentation is often difficult.
The orderly documentation of a Doppler examination is a normal part of the examination. It can be
divided into two parts:
1. A record of the image of the vessel examined, and
2. Documentation and organization of the complete
record.
transducer, and the recorded waveform with the Doppler indices. Such a record may be preserved as a video
print or on a computer. Admittedly, a video print is not
the optimal means of documentation in qualitative
terms, but in daily practice it is the medium most
easily revisited during repeat examinations. Of course,
if quality is important, storage on optical disk or on a
computer is to be preferred.
Complete documentation of a Doppler examination,
however, requires more information, i. e., a written record. This should include patient identifying data and
the indication for the examination. Additionally, it
should include fetal measurements to derive information on growth retardation and so underline the relevance of the examination. Even when Doppler findings
are normal, severe growth retardation is an important
finding that should lead to close supervision. Following
the fetal measurements the record should show
whether malformations have previously been excluded. Such an exclusion should be completed before
the Doppler examination, since malformations are
found specifically in the cohort of growth-retarded infants. The note recording the presence or absence of a
malformation should be followed by the findings of the
Doppler waveform, outlining the vessel examined and
the results in the form of Doppler indices. Next, the results should b e evaluated in the order of their clinical
significance; this will be followed by a diagnostic impression, and finally therapeutic recommendations. Finally, the corresponding Doppler images should be appended to the written report.
Basic Concepts
For instance, while documentation of the image of a
sonographic record made for the exclusion of malformations is very difficult to achieve, recording the
corresponding Doppler sonogram is easy. First the
blood vessel being examined is displayed as a B-mode
image on the monitor of the ultrasound instrument, including the superimposed Doppler beam. Next the
angle between the Doppler beam and the course of the
vessel is recorded by superimposing a line over the
vessel. Next, the Doppler waveform is displayed below
the B-mode image. The displayed vessel is identified by
superimposed text, unless it is easily identified on the
B-mode image. In addition, the Doppler indices must
be recorded. The documentation of a Doppler record
therefore includes the image of the selected vessel,
measurement of the angle between the vessel and the
65
1
Documentation
Sample Documentation Records
1. Patient: S. K., Date of birth: 4/3/1974
Requested: Fetal measurements and flow
Last menstrual period: 11/18/1997
Date of examination: 7/20/1998
Weeks of gestation:
calculated: 34 + 6
corrected: 32 + 5
Gravida 1, para 0
BPD
mm
110
100
FL
90
80
70
60
50
40
30
20
10
10 12 1 4 16 18 20
Implantation site
2286 24262830323436 384042
BPD
FL
TD
24 26 28 30 32 34 36 38 40 4220
22861012141618
+
+
+
BPD
FL
mm
110
100
90
80
70
60
TD
110
mm
100
90
80
70
60
50
40
30
20
10
66
Findings:
Fetal measurements: BPD: 77 mm, HC: 271mm, TD: 58 mm,
Fetus: Presentation: vertex
Placenta: Localization: fundus
Amniotic fluid: Normal
Other organs: Urinary bladder: full; gastric bubble: filled
Flow: Aorta resistance index (RI): 88 %, middle
Organs unremarkable
Evaluation: Measurements correspond to 29th to 30th
Diagnosis: Intrauterine pregnancy with abnormal
Suggested treatment: Close follow-up by tococardiogram. In-
Fig. 5.1 Documentation of fetal measurements in a pregnancy
showing severe fetal growth retardation in the 33rd week of gestation.
thoracic circumference: 192 mm, FL:
54 mm (Fig. 5.1)
cerebral a. RI: 79 %, umbilical a. RI: 71%
week of gestation. Amniotic fluid in normal
range. Flow borderline. Cephalic presentation.
development in the 33rd week with severe
fetal growth retardation and borderline
flow.
patient observation.
X = measurements from first examination
BPD = biparietal diameter
FL = femoral length
TD = thoracic diameter
HC = head circumference
Sample Documentation Records
Sample Documentation Records
2. Patient: S. K., Date of birth: 4/3/1974
Requested: Asymmetrical growth retarda-
tion Fetal measurements and
flow
Last menstrual period: 11/18/1997
Date of examination: 8/7/1998
Weeks of gestation:
calculated: 37 + 3
corrected: 34 + 5
BPD
FL
mm
110
100
90
80
70
60
50
40
30
20
10
Findings:
10 12 1 4 16 18 20
Implantation site
2286 24262830323436 384042
+
+
BPD
+
+
+
FL
TD
24 26 28 30 32 34 36 38 40 4220
22861012141618
+
+
+
+
BPD
FL
mm
110
100
90
80
70
60
TD
110
mm
100
90
80
70
60
50
40
30
20
10
Basic Concepts
Fetal measurements: BPD: 83 mm, HC: 291 mm, TD: 66 mm,
Fetus: Presentation: cephalic
Amniotic fluid: Oligohydramnios
Other organs: Urinary bladder: full; gastric bubble: filled
Flow: Aorta RI: 80 %
Evaluation: Fetal growth retardation, oligohydramnios.
Diagnosis: Gravida 1, fetal growth retardation about
Suggested treatment: Induction of labor Monday 8/10/1998
Fig. 5.2 Repeat examination. Since the examination record
shown in Fig. 5.1 the infant has clearly grown.
thoracic circumference: 208 mm, FL:
Fig.
60 mm (
5. 2)
Placenta on posterior wall, cephalic presentation.
Aortic flow normal.
four weeks
Flow normal
X = measurements from first and second examinations
BPD = biparietal diameter
FL = femoral length
TD = thoracic diameter
HC = head circumference
67
Documentation
Sample Documentation Records
1
3. Patient: A. S., Date of birth: 8/17/196 8
Requested: Flow evaluation
Last menstrual period: 3/2/1998
Date of examination: 9/21/1998
Weeks of gestation:
calculated: 29 + 0
corrected: 29 + 2
BPD
FL
mm
110
100
90
80
70
60
50
40
30
20
10
Findings:
10 12 1 4 16 18 20
Implantation site
2286 24262830323436 384042
BPD
FL
TD
24 26 28 30 32 34 36 38 40 4220
22861012141618
+
+
+
+
+
+
+
+
+
BPD
FL
mm
110
100
90
80
70
60
TD
110
mm
100
90
80
70
60
50
40
30
20
10
68
Fetal measurements: Cardiac activity: positive. BPD: 71 mm, HC:
Fetus: Presentation: cephalic
Placenta: Localization: anterior wall
Amniotic fluid: anhydramnios
Flow: Aorta RI: 89 %, middle cerebral a. RI: 72 %,
Evaluation: Fetal growth retardation about three to
Diagnosis: Flow requires regulation. Growth retarda-
Suggested treatment: Bed rest, tocolytics, close follow-up by to-
Fig 5.3 Documentation of repeated examinations of an infant
with severe growth retardation. The child has not grown since
the first examination.
239 mm, TD: 60 mm, thoracic circumfer-
5.3)
ence: 180mm, FL: 47 mm (
Fig.
umbilical a. RI: 72 %, maternal uterine a. RI
left: 63 %, right: 75 %.
four weeks, aortic flow borderline, large
flow in the middle cerebral a., in the
umbilical a. improved flow compared to
previous finding. Anhydramnios. Placenta
unremarkable. Uterine a. notched, right
uterine a. shows elevated RI.
tion three to four weeks, with no growth
during period of observation.
cocardiogram with inpatient observation.
Repeat flow in one week.
X = measurements from three separate examinations
BPD = biparietal diameter
FL = femoral length
TD = thoracic diameter
HC = head circumference
6 Common Errors in the Doppler Ultrasound Display of
Uterine Blood Flow and Fetal Vessels
Correct Display of Vessels with Normal Instrument Settings
Basic Concepts
Fig. 6.1 Uterine a. Color Doppler display of the uterine a.
crossing over the iliac vessels. Acute angle of incidence, indica-
tion of a notch in the spectrum.
Fig. 6.3 Fetal aorta. Acute angle, legend at the margin of the
display, wall filter and pulse repetition frequency (PRF) at optimal setting. Spectrum unremarkable.
Role of the Angle in the Doppler Examination
Fig. 6.2 Optimal method of examining the umbilical a. The
umbilical a. is shown with forward flow, the umbilical v. with
reverse flow (upper margin of display).
Fig. 6.4 Middle cerebral a. Angle almost 0°, optimal PRF, and
sample time duration optimizes the flow profile. Unremarkable
spectrum.
Fig. 6.5 Uterine a. Displayed is the origin of the vessel on the
other side of the iliac crossing. The Doppler angle is more ob-
tuse than in
there is a visible notch.
Fig
6.1. The resistance index (RI) is elevated and
69
Common Errors in the Doppler Ultrasound Display of Uterine Blood Flow and Fetal Vessels
1
Fig 6.6a Display of the umbilical a. Because the vessel is
poorly focused, the spectrum is not homogenous, the RI is elevated, and the umbilical v., shown in reverse flow, is displayed
only partially.
Fig. 6.7a The fetal aorta has been examined with a poor angle
of almost 90° in the center of the display. The RI is almost 85 %.
Fig. 6.6b The umbilical aa. are displayed three times in this
spectrum: 1. Reverse flow, 2. Forward flow with a high RI, 3. For-
ward flow with a low RI. When a choice must be made between
several such curves, the problems posed by the examination of
umbilical aa. become clear.
Fig.
Fig. 6.7b The same aorta as in
with an acute angle and at the margin of the display. Result:
Normal spectrum, unremarkable RI of ca. 75 %.
6.7a examined a little later
70
Fig. 6.8a Display of a fetal aorta examined with a 90° angle.
The incorrect examination technique results in zero flow in the
aorta.
Fig. 6.8b The same vessel examined a few seconds later with a
Doppler angle of 45°. Result: Normal flow profile; normal RI.
Possible Sources of Error in Doppler Ultrasound Examinations of Maternal and Fetal Vessels
Possible Sources of Error in Doppler Ultrasound Examinations of Maternal and Fetal
Vessels
Displaying the Uterine Artery
a b
Fig. 6.9a Typical flow profile of a uterine a. with an elevated
diastole and a RI of about 50 %.
Fig. 6.9b Same vessels as in Fig. 6.9a. Error: PRF is set too low,
with the result that no Doppler spectrum is displayed.
Basic Concepts
c d
Fig 6.9c The PRF is adapted, the Doppler spectrum appears.
However, systole continues to be incomplete and appears as a
“peak” above the baseline.
Fig. 6.9e A venous uterine vessel appears in reverse flow.
Fig. 6.9d In this case the spectrum of the uterine vessel is displayed optimally; the waveform can be evaluated.
e
a b
Fig. 6.10 a Uterine a. The vessel has been detected in B-mode
by color Doppler and has been captured by the Doppler beam at
an acute angle. The right-hand spectrum cannot be evaluated:
The baseline is too elevated and the waveform has been cut off
by the upper margin of the display. The waveform displayed by
the instrument suggests an elevated systole, but this cannot be
confirmed visually. In this case the waveform is somewhat un-
favorable, not very helpful.
Fig. 6.10 b Uterine a. Error: Baseline too high.
71
Common Errors in the Doppler Ultrasound Display of Uterine Blood Flow and Fetal Vessels
1
Fig. 6.10 c Error in the display of the uterine a. The waveform
displays faulty curves, due to too low amplification. Systole is incomplete.
Fig. 6.10 d The spectrum displaying the flow of the uterine a.
is complete here. The waveform represents the course of dias-
tole correctly.
Fig. 6.11 a Notched uterine a.
Fig. 6.11 b Incomplete display of the systole of a uterine a. PRF
set too low. Notch.
72
Fig. 6.11 c Same vessel as in Fig. 6.11 b . PRF was raised: Systole
is now displayed completely.
Possible Sources of Error in Doppler Ultrasound Examinations of Maternal and Fetal Vessels
Displaying the Umbilical Artery
a b
Fig. 6.12 a Display of the umbilical a. Error: The waveform cannot be interpreted, since neither systole nor diastole was recorded uniformly. The Doppler beam did not encompass the
coil of the umbilical cord in continuity.
Fig. 6.12 b The umbilical cord has been encompassed in continuity, the spectrum is continuous. Error: The wall filter is too
high. Systole is cut off. Possible corrective actions: Lower baseline; reduce wall filter.
Basic Concepts
a b
Fig. 6.13 a , b Display of umbilical a. Each figure shows two
coils of umbilical cord caught by the Doppler beam. As a result
there is a tracing on the baseline with forward flow, and a sec-
the first part of the tracing the spectrum is inverted.
a
Fig. 6.15 a Umbilical a. The spectrum is inverted, systolic
peaks are cut off and appear at the upper margin of the display.
ond curve at the upper margin of the display with reverse flow.
When the waveform is not homogeneous, it is not possible to
derive Doppler parameters.
컄Fig. 6.14 Umbilical a. with characteristic sawtooth pattern. In
b
Fig. 6.15 b The waveforms in
The angle is set too high, resulting in a curve that does not
touch the baseline.
6.15a have been corrected.
Fig.
examination of the vessel. Sample duration too high.
73
컄Fig. 6. 16 Umbilical a. Background noise is too strong in this