International Journal of Contemporary Pediatrics | July-September 2016 | Vol 3 | Issue 3 Page 1026
International Journal of Contemporary Pediatrics
Tirdia PR et al. Int J Contemp Pediatr. 2016 Aug;3(3):1026-1031
http://www.ijpediatrics.com
pISSN 2349-3283 | eISSN 2349-3291
Research Article
Accuracy of lung ultrasonography in diagnosis of community acquired
pneumonia in hospitalized children as compared to chest x-ray
Prahlad R. Tirdia, Shailja Vajpayee*, Jagdish Singh, RK Gupta
INTRODUCTION
Pneumonia is the leading cause of childhood morbidity
and mortality worldwide. The global annual incidence of
pneumonia is 150 to 156 million cases.
1
Each year,
approximately 1.4 million children die from pneumonia
and pneumonia accounts for almost 15% of childhood
mortality.
2
Estimated number of pneumonia deaths for
children under age 5 in India in 2013 was 174,000.
2
Diagnosis of community acquired pneumonia CAP) is
done clinically but with poor diagnostic specificity.
3,4
Chest X-ray (CXR) is considered as the first imaging step
for further evaluation. Even though plain radiographs
have small amounts of radiation dose exposure about
0.01-1.5 mSv, children are more susceptible to non-
deterministic stochastic effects of radiation than adults.
5,6
In addition, the interpretation of CXR findings is
dependent on the quality of the film and the expertise of
the reader.
7,8
ABSTRACT
Background:
The ultrasound signs of lung and pleural diseases described in adults are also found in pediatric
patients. LUS is at least as accurate as chest radiography in diagnosing pneumonia. The objective of the study was to
define the lung ultrasonography (LUS) characteristics at presentation and follow up of hospitalized children with
community acquired pneumonia (CAP) and to define the accuracy of LUS as compared to chest X-ray (CXR) in
diagnosing CAP.
Methods:
It was a hospital based prospective study done at department of paediatrics, SMS hospital, Jaipur. A total
of 139 children between 2 months to 18 years of age admitted in hospital with diagnosis of CAP who fulfilled the
inclusion and exclusion criteria were included in the study after obtaining informed written consent. Clinical driven
CXR was done on day of the admission. LUS was done in all patients. The LUS findings obtained were compared
with those of CXR. The data was analyzed by using standard statistical methods.
Results:
Of 139 patients, LUS characteristically shows sub pleural consolidation (absolute consolidation or with other
findings) in 93.5 % (130/139), confluent B-lines abnormalities 35.9 % (50/139), pleural line abnormalities in 17.2%
(24/139), and pleural effusion in 15.8 % (22/139) patients, while LUS was indicative of pneumonia in 136 (97.84%),
CXR was suggestive of pneumonia in 126 (90.64%) patients (p <0.01). The LUS had sensitivity of 97.84%.
Consolidation was reported in 130 (93.53%) patients by LUS as compared to 107 (76.97%) patients by CXR
(p<0.001). During follow up, LUS in seven patient initially showed increase in size of consolidation consistent with
clinical deterioration then gradual decrease in size of consolidation due change in antibiotics.
Conclusions:
LUS was highly accurate for the diagnosis as well as for follow up of CAP in hospitalized children. It
avoids the use of ionizing radiation. Therefore, the use of ultrasound needs to be encouraged not just as a valid
diagnostic alternative but as a necessary ethical choice.
Keywords: Lung ultrasound, Chest x-ray, Radiation, Imaging tool, Consolidation
Department of Pediatrics, SPMCHI, SMS Medical College and Attached Hospitals, Jaipur, Rajasthan, India
Received: 01 June 2016
Accepted: 02 July 2016
*Correspondence:
Dr. Shailja Vajpayee,
E-mail: dr.shlvajpayee@gmail.com
Copyright: © the author(s), publisher and licensee Medip Academy. This is an open-access article distributed under
the terms of the Creative Commons Attribution Non-Commercial License, which permits unrestricted non-commercial
use, distribution, and reproduction in any medium, provided the original work is properly cited.
DOI: http://dx.doi.org/10.18203/2349-3291.ijcp20162385
Tirdia PR et al. Int J Contemp Pediatr. 2016 Aug;3(3):1026-1031
International Journal of Contemporary Pediatrics | July-September 2016 | Vol 3 | Issue 3 Page 1027
The use of ultrasound for the evaluation of the lung is
relatively recent. Lung ultrasound (LUS) is inexpensive,
portable and non-ionizing imaging tool. It is relative easy
to teach.
9
The various studies had shown that LUS
performs well in adults.
10,11
LUS is being increasingly
studied in children and neonates in various thoracic
conditions.
12,13
In light of increasing awareness of radiation exposure
risks in children, we designed a study to define the LUS
characteristics of CAP in hospitalized children at
presentation and during follow up and to compare these
LUS findings with the CXR findings to determine if LUS
could serve as a useful alternative to CXR. To our best
knowledge, no previous such studies have been published
from India.
METHODS
It was a hospital based prospective observational study
done at department of paediatrics, SMS hospital, Jaipur
from April 2013 to March 2014. This study was approved
by the local ethics committee. Children between 2
months to 18 years of age who hospitalized for clinical
suspicion of CAP were enrolled. Cases fulfilling the
inclusion and exclusion criteria were included in the
study after obtaining informed written consent. Diagnosis
of pneumonia was confirmed by 2 expert pediatricians
clinically on the basis of initial presentation and follow
up clinical course (3). Clinical driven CXR was done on
day of the admission in PA view in erect posture. In all
patients, LUS was done on the day of the admission,
defined as day 1, within 24 hours of obtaining CXR.
Follow up LUS was done between days 3 and 6, 7 and
10, and 11 and 14. LUS was performed by trained
pediatric sonologist blinded to CXR findings but was
known to the clinical findings. LUS was performed using
3-7 MHz linear probe. A predesigned structural proforma
was used to collect information. Data was collected with
reference to clinical examination, routine investigations,
CXR findings and LUS findings. Continuous variables
are expressed as mean ± standard deviation (SD) values.
Categorical variables are expressed as numbers and
percentages. The data was analysed by using Chi square
test and Z- test.
Inclusion criteria
Clinical signs and symptoms suggesting CAP.
Children aged 2 months ≤18 years.
Presence of clinical driven CXR.
Availability of a paediatric sonographer expert in
LUS.
Exclusion criteria
Unwilling parents/guardians.
Patients with congenital or acquired heart disease,
chronic lung diseases and/or metabolic disorders.
Pre-established cases of pyrexia and cough other than
pneumonia.
Seriously ill patients or patients with multi organ
failure.
>24 hours duration between first LUS and CXR.
RESULTS
Table 1: Baseline characteristics of patients.
Patients, No. (%)
139 (100%)
Age, mean ± 95% CI, y
Median, y
3.28 ± 0.62
1.5
Sex,
Female
Male
No. (%)
48 (34.5%)
91 (65.5%)
Weight, mean ± 95% CI, kg
Median, kg
12.76 ± 1.62
9.2
Geographical distribution
Rural
Urban
Slum
No. (%)
72 (51.79%)
57 (41.00%)
10 (7.19%)
Immunization status
Complete immunization
Partial immunization
Unimmunized
No. (%)
61 (43.88%)
67 (48.20%)
11 (7.91%)
Previous history of
hospitalization due to
respiratory distress
Yes
No
No. (%)
22 (15.82%)
117 (84.17%)
Localization of LUS
characteristic
Right
Left
Both
No. (%)
97 (71.3%)
26 (19.1%)
13 (9.6%)
Lung consolidation shown by
LUS
CXR
p value
No. (%)
130 (93.53%)
107 (76.97%)
0.001
Table 2: LUS findings on day 1.
LUS characteristics
No. of patients (%)
N=139
Sub pleural lung consolidation
43 (30.93%)
Confluent B-lines + consolidation
44 (31.65%)
Confluent B-lines + Pleural line
abnormalities
2 (1.43%)
Consolidation + pleural line
abnormalities
22 (15.82%)
Pleural effusion + consolidation
21 (15.10%)
Focal or multiple confluent B-
lines
3 (2.15%)
Confluent B-lines + Pleural
effusion
1 (0.72%)
Normal
3 (2.15%)
Tirdia PR et al. Int J Contemp Pediatr. 2016 Aug;3(3):1026-1031
International Journal of Contemporary Pediatrics | July-September 2016 | Vol 3 | Issue 3 Page 1028
Table 3: Comparison of chest X-ray and LUS
characteristic findings for the diagnostic findings of
pneumonia.
USG
Positive
USG
negative
Total
p
value
Chest
X-ray
positive
125
1
126
(90.64%)
Chest
X-ray
negative
11
2
13
(9.35%)
Total
136
(97.84%)
3
(2.16%)
139
(100%)
< 0.01
A total 139 patients were enrolled. Descriptive
characteristics are given in Table 1. The most common
symptom of pneumonia was cough (95%) and most
common sign was tachypnea (99.23%). Most common
finding on auscultation was crepitation (58.99%). Oxygen
saturation of <90 % was observed in 12 (8.63%) patients.
Leucocytosis was observed as 60.8% in group of 2
months to 5 years, 77.41% in 5 to 10 years and 81.81% in
10 to 18 years of age. The difference was insignificant (p
= 0.1).
CXR showed consolidation (absolute or with other
abnormality) in 76.9% (107) patients, peribronchial
thickening in 10.07% (14) and synpneumonic pleural
effusion in 10.7% (15) patients. CXR was negative for
pneumonia in 13 patients.
On day 1 LUS characteristically showed sub pleural
consolidation (absolute or with other findings) in 93.5 %
(130), confluent B-lines abnormalities 35.9% (50),
pleural line abnormalities in 17.2% (24), and pleural
effusion in 15.8% (22) patients. Overall LUS findings are
tabulated in Table 2.
Of 139 patients who were clinically diagnosed as
pneumonia, CXR was suggestive of pneumonia in 126
(90.64%) patients while LUS was indicative of
pneumonia in 136 (97.84%) patients (Table 3) (p=0.01).
One patient with negative LUS had abnormal CXR but11
patients with negative CXR had LUS findings suggestive
of pneumonia with clinical course consistent with
pneumonia (p <0.01). LUS was negative in 3 patients
with clinical course consistent with pneumonia while
CXR failed to detect abnormality in 13 patients. The
difference was significant.
In this study, consolidation and pleural effusion were two
characteristics findings common in CXR and LUS.
Consolidation was reported in 130 (93.53%) patients by
LUS and in 107 (76.97%) patients by CXR and the
difference was statistically highly significant (p<0.001).
A synpneumonic pleural effusion was reported in 22
(15.83%) patients by LUS as compare to 15 (5.03%) by
CXR.
Table 4: Follow up of lung consolidation and pleural effusion as reported by LUS.
Maximum thickness of
consolidation
[pleural effusion] mm
No. of patients (%)
Day 1
Day 3-6
Day 7-10
Day 11-14
< 15 mm
57 (41.0%) [13]
70 (50.3%) [16]
30 (21.6%) [10]
7 (5.03%) [2]
15 – 29 mm
66 (47.4%) [8]
15 (10.7%) [2]
6 (4.3%) [0]
5 (3.5%) [1]
≥ 30 mm
7 (5.0%) [1]
5 (3.5%) [1]
2 (1.4%) [0]
0 (0.0%) [0]
Total
130 (93.52%)
[22 (15.8%)]
90 (64.75%)
[19 (13.7%)]
38 (27.34%)
[10 (7.2%)]
12 (8.63%)
[3 (2.2%)]
Table 5: Follow-up characteristics of LUS in patients.
LUS characteristics
No. of patients (%)
Day 1
Day 3-6
Day 7-10
Day 11-14
Confluent B-lines
50 (36.0%)
40 (28.8%)
20 (14.4%)
8 (5.8%)
Pleural line abnormalities
24 (17.3%)
18 (13.0%)
12 (8.6%)
6 (4.3%)
Total
74 (53.24%)
58 (41.73%)
32 (23.02%)
14 (10.07%)
Follow up LUS characteristic are summarized in Table 4
and 5. On day 1, LUS showed consolidation in 130
(93.52%) with maximum thickness of <15 mm in 57
(43.84%), between 15-29 mm in 66 (50.76%) while ≥30
mm in 7 (5.38%). During follow up between day 3-6, 7-
10, and 11-14 of illness LUS shows consolidation in 90
(64.75%), 38 (27.34%) and 12 (8.63%) patients
respectively. The size of consolidation steadily declined
on subsequent follow-up LUS consistent with clinical
improvement reflected by increase in number of patients
with consolidation thickness <15 mm on day 3-6 as other
patient who were initially have more severe findings falls
Tirdia PR et al. Int J Contemp Pediatr. 2016 Aug;3(3):1026-1031
International Journal of Contemporary Pediatrics | July-September 2016 | Vol 3 | Issue 3 Page 1029
in this category after treatment. LUS in seven patients
initially showed increase in size of consolidation
consistent with clinical deterioration then gradual
decrease in size of consolidation due to change in
treatment. A total of 22 patients had pleural effusion on
day 1 with maximum thickness of <15 mm in 13 (59.1%),
15-29 mm in 8 (36.4%) and ≥30 mm in 1 (4.5%) with
decrease in size consistently during follow up. Similar
improvement was reported for other LUS findings.
DISCUSSION
Early diagnosis and management of pneumonia are
critical to short- and long-term health outcomes. Clinical
examination is highly sensitive but lacks specificity and
results in over diagnosis contributing to the overuse of
antibiotics.
14
CXR is considered the test of choice for
further evaluation. The main limitations of radiography is
the risk of damage from ionizing radiation with a greater
risk than adults because children have more rapidly
dividing cells and increased life expectancy.
5,6
Other
concerns with radiography are great variability in the
interpretation lack of reproducibility and delay in
availability of the film.
7,8
Also in complicated pneumonia
CXR is less reliable and chest computed tomography
(CT) scan is known to be the gold standard.
15
However,
its use has been discouraged due to high radiation, high
cost and the need for sedation in young children.
Medical radiation exposure is increasing rapidly. The
radiological risk is cumulative in nature. The chest is the
most frequently evaluated region of the body in children.
There is research that suggests hepatoblastoma risk may
increase due to repeated chest X-rays in intensive care
unit patients.
5,6
Unfortunately, paediatricians are often
unaware of these risks. It is often possible to significantly
decrease medical radiation exposure without
compromising patient care.
Weinberg et al first described the use of LUS in
evaluating CAP.
16
Subsequent studies have demonstrated
that LUS is able to diagnose pneumonia in adults with
high accuracy.
10,11
Later on studies had demonstrated
high efficacy of LUS in diagnosing pneumonia in
children.
17,18
Recently LUS has been indicated as a
clinically useful diagnostic tool in pediatric patients with
suspected pneumonia.
19
The LUS features of pneumonia
mainly included sub pleural lung consolidation, pleural
line abnormalities, confluent B-lines and synpneumonic
pleural effusions.
17,18
In our study, the various LUS findings are similar to the
data in the literature. The detection of pneumonia using
LUS was better (97.84%) than with chest radiography
(90.64%). LUS was able to detect consolidation in 130
(93.53%) patients as compared to 107 (76.97%) patients
by CXR of total 139 patients. LUS was normal in 3
patients with clinical course consistent with pneumonia
while CXR failed to detect abnormality in 13 patients.
MC Ho et al also found similar results with chest
radiography able to detect 151 (92.6%), whereas LUS
detected 159 (97.5%) out of 163 patients with
pneumonia.
20
Pereda in meta-analysis found that LUS
had a sensitivity of 96% and specificity of 93% (21).
Other published data also showed that LUS is more
sensitive than CXR in the diagnosis of pneumonia in
children.
22-24
This study also addresses the follow-up LUS
characteristics, showing the dynamic changes of pleuro-
pulmonary abnormalities over time determining the
effectiveness of LUS in the on-going management of
pneumonia over the course of an illness. The size of
consolidation and other abnormalities showed persistent
improvement on subsequent follow-up LUS examination
consistent with clinical improvement. Similar results
were found by Caiulo et al and Stefania et al.
22,23
In this
study, LUS in seven patient initially showed increase in
size of consolidation consistent with clinical deterioration
then gradual decrease in size of consolidation due to
change in treatment.
Thus, our study demonstrates that LUS is safe and
accurate for the diagnosis suspected cases of CAP and it
is more sensitive than CXR and allows a radiation free
follow up of patients.
Some technical advantages such as shorter thoracic
width, thinner chest wall, and small lung mass
theoretically enable LUS examination in children easier
than in adults.
19
Pleural effusion, lung consolidation,
interstitial syndrome, and pneumothorax are accessible to
LUS. LUS is useful in the evaluation of lung
consolidation as it can also differentiate consolidations
due to pulmonary embolism, pneumonia, or atelectasis.
25
LUS also has the potential for diagnosing the nature of
the effusion and differentiating bacterial and viral
pneumonia.
26,27
LUS also had a consistently high
diagnostic accuracy of pneumonia when compared with
chest CT scan as the gold standard.
28
Further research regarding the role of colour Doppler
sonography, spectral curve analysis and contrast-
enhanced ultrasound is necessary, especially with respect
to differential diagnosis of lung consolidations and early
detection of complications. Also while LUS is best
performed by trained sonographers, medical students,
doctors and other health care workers at the bedside are
now being trained in it use, albeit cautiously.
9,18
Recent
advances in technology have made portable or handheld
ultrasonography machines more available. This raises the
potential for diagnostic capabilities in rural and remote
settings where other imaging modalities are not available.
CONCLUSION
Lung ultrasound shows high accuracy in the detection of
pneumonia and possibility of a follow-up without
exposure to ionizing radiation. It does not require
sedation and can be repeated at any time.
Tirdia PR et al. Int J Contemp Pediatr. 2016 Aug;3(3):1026-1031
International Journal of Contemporary Pediatrics | July-September 2016 | Vol 3 | Issue 3 Page 1030
ACKNOWLEDGEMENTS
The authors are thankful to Dr. Anu Bhandari, professor,
department of radiology, SMS medical college for her
assistance.
Funding: No funding sources
Conflict of interest: None declared
Ethical approval: The study was approved by the
Institutional Ethics Committee
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