Ultrasound Obstet Gynecol 2010; 35: 578–582
Published online 22 February 2010 in Wiley InterScience (www.interscience.wiley.com). DOI: 10.1002/uog.7592
Lung tissue perfusion in congenital diaphragmatic
hernia and association with the lung-to-head ratio
and intrapulmonary artery pulsed Doppler
O. MORENO-ALVAREZ*, R. CRUZ-MARTINEZ*, E. HERNANDEZ-ANDRADE*, E. DONE†,
O. GÓMEZ*, J. DEPREST† and E. GRATACOS*
*Fetal and Perinatal Medicine Research Group, Department of Maternal-Fetal Medicine Hospital Clinic-IDIBAPS, University of Barcelona
and Centre for Biomedical Research on Rare Diseases (CIBER-ER), Barcelona, Spain and †Department of Obstetrics and Gynecology,
University Hospitals Leuven, Leuven, Belgium
K E Y W O R D S: congenital diaphragmatic hernia; Doppler; fractional moving blood volume; lung perfusion; lung-to-head ratio
ABSTRACT
Objective To evaluate lung tissue perfusion in fetuses
with congenital diaphragmatic hernia (CDH) and to
explore the association of lung tissue perfusion with
the lung area to head circumference ratio (LHR) and
intrapulmonary artery pulsed Doppler.
Methods Fetuses with isolated left CDH were evaluated
and compared with a group of fetuses without CDH,
which were sampled from our general population and
matched by gestational age at inclusion. Lung tissue
perfusion measured using fractional moving blood volume
(FMBV), the observed to expected (O/E) LHR and pulsed
Doppler of the proximal intrapulmonary artery were
evaluated in the lung contralateral to the side of the hernia.
Doppler waveform analysis included the pulsatility index
(PI), the peak early diastolic reversed flow (PEDRF) and
the peak systolic velocity (PSV). All Doppler parameters
were converted into Z-scores for gestational age. The
associations between FMBV and O/E-LHR and between
FMBV and intrapulmonary arterial Doppler parameters
were analyzed using multiple linear regression, adjusted
by gestational age.
Results A total of 190 fetuses (95 with CDH and
95 controls) were evaluated. Fetuses with CDH
showed significantly lower lung FMBV (26.8 (SD 8.4)
vs. 37.9 (SD 8.1)%; P < 0.001) than controls. Lung tissue
perfusion correlated positively with O/E-LHR (r = 0.37;
P < 0.001) and negatively with intrapulmonary artery PI
(r = −0.31; P < 0.001), PEDRF (r = −0.43; P < 0.001)
and PSV (r = −0.18; P = 0.03).
Conclusions Fetuses with CDH have decreased lung
tissue perfusion, which is associated with decreased lung
growth and increased intrapulmonary artery impedance.
Copyright  2010 ISUOG. Published by John Wiley &
Sons, Ltd.
INTRODUCTION
Isolated congenital diaphragmatic hernia (CDH) occurs
with an incidence of one in 5000 live births, and accounts
for about 8% of all major congenital abnormalities.
CDH is associated with a neonatal mortality rate of
47–60%, primarily as a result of lethal pulmonary
hypoplasia1 – 3 . The early compression, produced by the
abdominal organs, of the lung might affect the normal
development of the vascular and bronchial trees, either by
a mechanical effect or by interfering with the biochemical
process of maturation. Histopathological studies have
demonstrated that the lungs of fetuses with CDH
show an abnormal architecture of the alveolar septa
and respiratory acinus, a decreased number of arterial
branches and greater arterial wall thickness as a result
of an increase in the muscularization of intrapulmonary
vessels4 – 7 .
The best predictor with which to evaluate the severity of
CDH is estimation of the lung area to head circumference
ratio (LHR) or the observed to expected lung-to-head ratio
(O/E-LHR) when this value is adjusted by gestational
age8 . However, its predictive capacity at intermediate
O/E-LHR values is not very accurate and should be
complemented with alternative parameters to improve
prognosis in fetuses with CDH.
Correspondence to: Dr E. Gratacos, Maternal-Fetal Medicine Department, Hospital Clinic, University of Barcelona, Sabino de Arana 1,
08028 Barcelona, Spain (e-mail: [email protected])
Accepted: 30 June 2009
Copyright  2010 ISUOG. Published by John Wiley & Sons, Ltd.
ORIGINAL PAPER
Lung perfusion in CDH fetuses
Clinical studies in fetuses with severe pulmonary
hypoplasia have reported increased blood flow impedance
in the intrapulmonary vessels9 – 11 and that impedance
parameters correlate negatively with the degree of
lung growth, as measured using the O/E-LHR11 . The
pulmonary vasculature has also been evaluated as a
potential prenatal predictor of pulmonary hypoplasia
using conventional two-dimensional (2D) and threedimensional (3D) power Doppler imaging. However,
these methods represent semiquantitative estimations
which have been shown to be subject to substantial bias
in experimental conditions12,13 . By contrast, fractional
moving blood volume (FMBV), a methodology that
compensates for common estimation errors, has been
validated in experimental models and human fetuses and
has demonstrated good reproducibility and an excellent
correlation with blood flow gold standards in animal
models14,15 . In a previous study we reported decreased
fetal lung tissue perfusion in a rabbit model of CDH16 .
In this study, we evaluated lung perfusion in human
fetuses using the FMBV methodology. We compared lung
perfusion between fetuses with CDH and controls and
explored its association with the O/E-LHR and pulmonary
artery pulsed Doppler parameters.
METHODS
Subjects
A cohort of singleton fetuses with confirmed left isolated CDH were evaluated and compared with a group
of fetuses without CDH, which were sampled from our
general population and matched by gestational age at
inclusion in the period between October 2006 and May
2009 at the Fetal Medicine Units of the Hospital Clinic,
Barcelona, Spain and at the University Hospitals Leuven,
Leuven, Belgium. Exclusion criteria were (i) other congenital malformations and (ii) chromosomal abnormalities.
The protocol was approved by the hospital ethics committee, and patients provided written informed consent.
Ultrasound examinations and Doppler parameters
All ultrasound examinations were performed by one of
three experienced examiners (O.M.A., R.C.M., E.D.)
using Siemens Sonoline Antares (Siemens Medical Systems, Malvern, PA, USA) or Voluson 730 Expert (GE
Medical Systems, Milwaukee, WI, USA) ultrasound equipment with a 6–2-MHz linear curved-array transducer.
The lung contralateral to the side of the hernia was evaluated in a cross-sectional view of the fetal thorax at level
of the cardiac four-chamber view.
The LHR was estimated by multiplication of the
longest diameter by its widest perpendicular diameter,
as previously described17 . The expected LHR values
were calculated using normal reference ranges, according to gestational age, as −3.4802 + (0.3995 × GA) −
(0.0048 × GA2 )8 . The observed LHR was compared with
the expected LHR in order to calculate the O/E-LHR
Copyright  2010 ISUOG. Published by John Wiley & Sons, Ltd.
579
and was expressed as a percentage. For the analysis,
fetuses with CDH were divided into four groups based on
the O/E-LHR and the severity of pulmonary hypoplasia: Group 1, n = 10 (O/E-LHR < 15%); Group 2,
n = 36 (O/E-LHR 16–25%); Group 3, n = 39 (O/E-LHR
26–35%, survival 65%); and Group 4, n = 10 (O/E-LHR
>35%).
In both cases and controls, the lung Doppler
parameters were estimated in the right lung. Using color
directional pulsed Doppler, the proximal branch of the
intrapulmonary artery was located. Spectral Doppler
was applied and the characteristic pulmonary blood
flow waveform was identified as previously described
by Laudy et al.18,19 and Moreno-Alvarez et al.11 . The
Doppler sample volume (2 mm) was placed close to the
emerging most proximal branch of the intrapulmonary
artery, with an angle of insonation as close to 0 as
possible. A high-pass wall filter of 70 Hz was used to
record slow flow movements and to avoid sound artifacts.
Doppler recordings, including three to five good-quality
similar waveforms, were used for analysis. All studies
were performed in the absence of fetal corporal or
respiratory movements and, if required, with voluntary
maternal suspended breathing. Mechanical and thermal
indices were maintained below 1. The waveform analysis
included: (a) pulsatility index (PI); (b) peak early diastolic
reversed flow (PEDRF) and (c) peak systolic velocity
(PSV). All values were converted into Z-scores according
to previously reported normal ranges11 .
Using power Doppler ultrasound, lung blood perfusion
was evaluated. The power Doppler color box was placed
where the lung vessels were clearly visualized, and kept as
small as possible to include most of the lung but minimize
flash artifacts from the heart. Five consecutive high-quality
images with no artifacts were recorded using the following
fixed ultrasound setting: gray-scale image for obstetrics,
medium persistence, wall filter of 1, gain level of 1 and
pulsed repetition frequency of 977 Hz. All images were
examined offline and the FMBV was estimated using the
MATLAB software 7.5 (The MathWorks, Natick, MA,
USA), as previously described14 . The mean FMBV from
all five images was considered as representative for that
specific case and is expressed as a percentage. The region
of interest was delimited as described previously15 ; the
baseline was defined as an extension of an imaginary line
through the right atrium and crux of the interventricular
and interatrial septa to the left ventricle (Figure 1). All
studies were performed before any fetal intervention,
and only one set of measurements for each patient was
included in the analysis.
Statistical analysis
The Student’s t-test and Pearson’s chi-square test were
used to compare quantitative and qualitative data,
respectively. The associations between lung FMBV and
O/E-LHR and between lung FMBV and pulsed Doppler
parameters were analyzed using linear logistic regression
adjusted by gestational age. Statistical analysis was
Ultrasound Obstet Gynecol 2010; 35: 578–582.
Moreno-Alvarez et al.
580
Table 1 Maternal and neonatal clinical characteristics of the
studied groups
Characteristic
Figure 1 Power Doppler image from the fetal thorax with the
region of interest delimited to estimate lung perfusion.
performed using Statistical Package for the Social Sciences
(SPSS 15.0; SPSS Inc., Chicago, IL, USA) software.
RESULTS
A total of 190 fetuses (95 CDH and 95 controls)
fulfilled the entry criteria. Table 1 shows the maternal and
neonatal clinical characteristics of the studied population.
Fetuses with CDH showed significantly lower mean
lung FMBV values than controls (26.8 (SD 8.4) vs. 37.9
(SD 8.1)%; P < 0.001). Figure 2 depicts the differences
in lung perfusion among the four O/E-LHR groups. The
lung FMBV values increased linearly and significantly
when fetuses with CDH were classified according to the
degree of lung growth. Likewise, lung perfusion correlated
positively with the O/E-LHR (r = 0.37, P < 0.001)
(Figure 3) and negatively with intrapulmonary artery PI
(r = −0.31, P < 0.001), PEDRF (r = −0.43, P < 0.001)
and PSV (r = −0.18, P = 0.03).
DISCUSSION
This study provides evidence that fetuses with CDH show
decreased lung tissue perfusion, as estimated using the
FMBV, and that this parameter is associated with the
degree of lung growth and intrapulmonary blood flow
impedance, as measured using the O/E-LHR and spectral
Doppler, respectively.
Our findings add to the body of evidence, demonstrated
in clinical and experimental models, that CDH fetuses
with severe pulmonary hypoplasia have abnormal
pulmonary Doppler parameters in utero11,20 – 22 . Previous
studies have assessed pulmonary blood flow in fetuses with
CDH using power Doppler to explore its potential value
in the prediction of lethal pulmonary hypoplasia. MahieuCaputo et al.12 qualitatively assessed the pulmonary
vasculature using conventional 2D power Doppler
imaging. Pulmonary Doppler evaluation was classified
according to the segments of pulmonary arteries
Copyright  2010 ISUOG. Published by John Wiley & Sons, Ltd.
GA at ultrasound
examination (weeks)
Maternal age (years)
Primiparous
Non-Caucasian ethnicity
GA at FETO (weeks)
Occlusion time (days)
GA at occlusion removal
(weeks)
Postnatal balloon removal
PPROM
Induction
Cesarean section
GA at delivery (weeks)
Birth weight (g)
Male/female ratio
5-min Apgar score < 7
Extracorporeal membrane
oxygenation
Inhaled nitric oxide
High-frequency ventilation
Neonatal age when CDH
repaired (days)
Length of stay in neonatal
unit (days)
Survival
CDH
(n = 95)
Controls
(n = 95)
P*
27.9 (2.5)
28.4 (2.5)
0.29
29.7 (6.2)
46.5
9.1
28.7 (2.1)
34.4 (14.1)
33.6 (1.7)
29.1 (6.7)
52.0
15.9
NA
NA
NA
0.55
0.63
0.27
7.4
26.3
9.5
35.8
36.1 (3.2)
2552 (652)
55/40
8.4
6.3
NA
NA
8.4
22.2
39.6 (1.4)
3262 (434)
49/46
0
NA
45.3
92.5
3.3 (6.1)
NA
NA
NA
40.2 (25.4)
NA
50.6
NA
0.80
0.21
< 0.01
< 0.01
0.90
< 0.01
Results are expressed as mean (SD) or %. *Student’s t-test for
independent samples or Pearson’s chi-square test. CDH, congenital
diaphragmatic hernia; FETO, fetoscopic tracheal occlusion; GA,
gestational age; NA, not applicable; PPROM, preterm premature
rupture of membranes.
visualized. The authors reported that fetuses in which
fewer than three divisions of pulmonary arteries were
imaged showed higher neonatal mortality. In another
study, Ruano et al.13 used a semiquantitative method to
evaluate pulmonary perfusion by 3D power Doppler and
reported decreased values in fetuses with CDH and a
negative association with pulmonary hypertension. In a
rabbit model of CDH, we have previously reported that
lung tissue perfusion is decreased in fetuses with CDH,
and that this parameter is positively correlated with the
lung area to body weight ratio16 .
Reduced perfusion in CDH possibly reflects a mixed
component of intrinsic changes in the pulmonary vascular
tree with mechanical lung compression. Mechanical
compression is supported by the correlation with O/ELHR and by the fact that in animal models decreased
lung tissue perfusion and increased intrapulmonary PI
are immediately observed after the surgical induction of
CDH16 , before any histological change may have taken
place. However, in addition to the mechanical component,
the data of the present study strongly support that lung
tissue perfusion also reflects intrinsic lung developmental
changes. Although there was a significant correlation with
lung size, estimated by the O/E-LHR, in a proportion
of cases substantial differences between lung size and
Ultrasound Obstet Gynecol 2010; 35: 578–582.
Lung perfusion in CDH fetuses
581
40
Mean lung FMBV (%)
30
20
10
0
1
2
3
O/E-LHR group
4
Figure 2 Mean (SD) fractional moving blood volume (FMBV) in
the four observed to expected lung-to-head ratio (O/E-LHR)
groups. There was a linear increase in FMBV across study groups
(P < 0.01). Group 1, n = 10 (O/E-LHR < 15%); Group 2, n = 36
(O/E-LHR 16–25%); Group 3, n = 39 (O/E-LHR 26–35%,
survival 65%); and Group 4, n = 10 (O/E-LHR > 35%).
50
Lung FMBV (%)
40
30
ACKNOWLEDGMENTS
20
10
0
in cases of CDH which had apparently similar lung
sizes prenatally. Thus, while it is well demonstrated that
CDH fetuses have increased thickness of the muscular
layer of the intrapulmonary artery vessel walls4 – 7 , the
degree of vascular abnormalities might be variable from
case to case. From a clinical perspective, the results of
this study support the notion that lung perfusion could
be combined with O/E-LHR to refine the prediction of
morbidity and mortality in a composite prognostic score.
The evaluation of the predictive value of tissue perfusion
is now underway.
This study has some limitations. First, as for any
imaging method, FMBV provides only an indirect estimate
of blood perfusion. However, the technique has shown an
excellent correlation with gold standards in the estimation
of true tissue blood flow in animal experiments, with good
reproducibility reported in the assessment of fetal lung
perfusion14,15 . Second, we acknowledge that the clinical
application of our findings is limited because there are
currently no clinical methods available with which to
measure tissue lung perfusion accurately. Some tools now
incorporated into commercial devices have substantial
limitations in the estimation of perfusion owing to a lack
of correction for attenuation and depth23 . However, it is
expected that future commercial software tools might
incorporate algorithms such as those used in FMBV
estimates.
In conclusion, these data indicate that lung tissue perfusion, assessed using FMBV, is substantially
reduced in CDH. Lung perfusion is moderately correlated with the O/E-LHR but there are substantial
differences between the two parameters in a proportion of fetuses, which raises the possibility that
power Doppler assessment could complement O/ELHR to estimate the likelihood of survival, with
and without prenatal therapy, of fetuses affected
with CDH.
0
20
40
O/E-LHR (%)
60
80
Figure 3 Correlation between lung tissue perfusion and observed to
expected lung-to-head ratio (O/E-LHR) (r = 0.37, P < 0.001).
FMBV, fractional moving blood volume.
tissue perfusion were observed. We have previously
reported similar findings when the Doppler PI in the
pulmonary artery was correlated with the LHR11 . These
individual differences support the existence of different
histological forms under the common diagnosis of CDH,
which could partially explain the substantial variability
in clinical behavior and mortality that can be observed
Copyright  2010 ISUOG. Published by John Wiley & Sons, Ltd.
This study was supported by the Fondo de Investigación
Sanitaria (FIS) of the Ministerio de Sanidad y Consumo
with the grant PI 06/0585 and by EuroSTEC LSHB-CT2006-037409. R.C. and E.D. are supported by Marie
Curie Host Fellowships for Early Stage Researchers
(FETAL-MED-019707-2). E.H.A. was supported by a
Juan de la Cierva postdoctoral fellowship (Fondo de
Investigaciones Sanitarias, Spain). Oscar Moreno and
Rogelio Cruz wish to thank the Mexican National Council
for Science and Technology (CONACyT), in Mexico City,
for supporting their predoctoral stay at the Hospital Clinic
in Barcelona, Spain.
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