Tanaka et al. BMC Pediatrics(2019) 19:162
https://doi.org/10.1186/s12887-019-1531-6

RESEARCH ARTICLE

Open Access

Effect of aspiration on the lungs in children:
a comparison using chest computed
tomography findings
Nobukazu Tanaka1* , Kanji Nohara2, Akihito Ueda3, Tamami Katayama4, Miyuki Ushio4, Nami Fujii1 andTakayoshi Sakai2

Abstract
Background: Detecting and addressing aspiration early in children with dysphagia, such as those with cerebral
palsy, is important for preventing aspiration pneumonia. The current gold standards for assessing aspiration are
swallowing function tests, such as fiberoptic endoscopic evaluation of swallowing (FEES) and videofluorographic
swallowing study; however, the relationship between aspiration of secretion vs aspiration of foodstuff andpulmonary injury is unclear. To clarify this relationship, we examined the correlations between pneumonia findings
from chest computed tomography (CT) and the presence or absence of aspiration detected by FEES.
Methods: Eighty-five children (11 years 2 months ±7 years 2 months) underwent FEES and chest CT. Based on the
FEES findings, the participants were divided into groups: with and without food aspiration, and with and without
saliva aspiration. Correlations between chest CT findings of pneumonia and the presence or absence of each typeof aspiration were then examined.
Results: No significant correlations were observed between food aspiration and chest CT findings of pneumonia,
whereas saliva aspiration and chest CT findings of pneumonia were significantly correlated. In addition, saliva
aspiration was significantly associated with bronchial wall thickening (p < 0.01) and atelectasis (p < 0.05).
Conclusions: Our findings in children suggest that: (1) the presence or absence of food aspiration detected by
FEES evaluation has little correlation with pneumonia, and (2) the presence or absence of saliva aspiration may be
an indicator of aspiration pneumonia risk.
Keywords: Aspiration, Child, Computed tomography, Dysphagia, Pneumonia

BackgroundChildren with diseases, such as cerebral palsy or diseases
involving multiple disabilities, have swallowing impairment[1]. The prevalence of dysphagia is extremely high—from
85 to 89% [2, 3] to as high as 99% [4]—in children with severe cerebral palsy. Therefore, addressing dysphagia is an
essential part of caring for children with disabilities.
Aspiration and aspiration pneumonia are the most important problems associated with dysphagia in children.
Data from articles and clinical reports vary regarding thefrequency of aspiration and aspiration-related pneumonia* Correspondence: n-tanaka@dent.osaka-u.ac.jp
1
Division of Oral and Facial Disorders, Osaka University Dental Hospital, 1-8,
Yamadaoka, Suita, Osaka 565-0871, Japan
Full list of author information is available at the end of the article

with aspiration reported in 21–79% of children with certain diseases or disabilities [5]. Moreover, most (60–100%)
cases of aspiration involve silent aspiration [5]. In one
study, the investigators found aspiration-related pneumonia in nearly half of the children with various illnesses
who were hospitalized for pneumonia [6]. This finding
and other data suggest a strong association between aspiration and pneumonia in children with disabilities [7–9].
Videofluoroscopy and videoendoscopy are the gold
standard methods for detecting aspiration—in particular,silent aspiration—and are more precise than other clinical methods for assessing children [10]. In clinical practice, assessments by a videofluoroscopic swallowing
study (VFSS) or by fiberoptic endoscopic evaluation ofswallowing (FEES) are often used to determine how to© The Author(s). 2019 Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0
International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, andreproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to
the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver(http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.

Tanaka et al. BMC Pediatrics(2019) 19:162

address food aspiration. To prevent pneumonia, the recommended methods to address food aspiration include
adjusting an individual’s posture when eating or changing to a diet with food textures (e.g., mush, minced,
thickened with water) that are safer than those of foods
that are aspirated, limiting oral intake, and stopping oral
feeding [1, 11]. Thus, the aspiration of food is associatedwith pneumonia onset. However, studies of adults havenot found a relationship between pneumonia and food aspiration detected by VFSS or FEES [12–14]. Furthermore,insufficient evidence exists demonstrating that limiting
oral intake prevents pneumonia [15]. Therefore, deciding
whether to limit oral intake based on the presence or absence of aspiration could result in overmanagement.
To examine the relationship between pneumonia inchildren and aspiration detected by a swallowing function
test, we investigated the correlation between pneumonia
findings in chest computed tomography (CT) and thepresence or absence of aspiration, as detected by FEES
that was conducted within 1 week of the CT examination.

Methods
Participants

The participants were 126 disabled children with severe
motor disturbances and developmental retardation who
received outpatient care for dysphagia at the Osaka Developmental Rehabilitation Center (Osaka, Japan) from2012 to 2014 and who underwent FEES to evaluate swallowing function. Eighty-five children underwent FEES
evaluations, after having undergone chest CT, as part ofthe standard medical practice, in the preceding week.
They were included if their CT results could be analyzed. The exclusion criteria were as follows: (1) chest
CT was administered more than 1 week before the FEES
(36 participants) and (2) poor image quality due to body
movements or other factors that made analysis difficult(5 participants).
The participants included 51 boys and 34 girls whosemean age was 11 years 2 months±7 years 2 months (agerange, 11 months–26 years). Based on the criteria of theInternational Classification of Diseases, 10th revision,
the children’s underlying diseases were categorized as
cerebral palsy and other paralytic syndromes (74.1%),
episodic and paroxysmal disorders (22.3%), chromosomal abnormalities not elsewhere classified (9.4%), congenital malformations of the nervous system (9.4%),
diseases of the myoneural junction and muscles (5.9%),other disorders originating in the perinatal period(5.9%), and other diseases such as cerebrovascular accident and metabolic disorder (total, 11.8%). Many participants had concomitant diseases, the most common
being cerebral palsy and epilepsy.
All participants received nutrition orally: by total oral
intake in 43 (50.6%) children and by the combined use

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of tube feeding in 42 (49.4%) children. Pneumonia history was confirmed from medical records and other clinical notes.
Procedure
Swallowing function test

The FEES was used as the swallowing function test [16, 17].
It involves a team approach, which entails the participationand cooperation of multiple disciplines. In particular, dentists, pediatricians, speech therapists, nurses, dental hygienists, and caregivers took part in the testing. The test was
explained to the caregivers beforehand. For the test, thecaregivers brought the food and eating utensils that the participants used regularly or daily. In addition, posture, feeding assistance, and other circumstances under which theparticipants regularly ate were reproduced as closely as possible for the test. The participants were fed the test food bya caregiver or speech therapist. The test food was colored
beforehand with green food dye to make it easy to visualize
during the assessment. On conducting the test, the absenceof fever, low oxygen saturation, fatigue, or other acute
symptoms were confirmed in all patients.
After inserting the endoscope, it was manipulated to alow position so that the vestibule of the larynx was in
the center of the field of view. After observing the larynx
to check for saliva aspiration, the test food was ingested
to continue the test. At least two mouthfuls of each texture of the test food were ingested. Aspiration wasassessed using the penetration-aspiration scale (PAS),
which is the standard assessment criterion for FEES forfood [18]. Participants who cried when the fibroscope
was inserted or who could not be evaluated because of
hypertonia were excluded (3 participants). Videos of thetests were viewed by a dentist, pediatrician, and speechtherapist. Based on the results, the participants wereplaced into the aspiration group (PAS score of 5–8) or
the nonaspiration group (PAS score of 1–4). The children were then categorized into the food aspirationgroup or the saliva aspiration group.
History of pneumonia

History of pneumonia was confirmed, based on the presence or absence of pneumonia in the patient’s medical
records in the year before the FEES. Patients with thisinformation in their records were considered as having ahistory of pneumonia.
Chest CT

Chest CT images were obtained using the Asteion
TSX-021B CT scanner (Toshiba Medical Systems, Tokyo,
Japan). The imaging parameters were 120 kVp, 1.375:1 pitch,
and an automatically adjusted current of 100–150 mA. Axial
images were acquired at 2-mm slice thickness.

Tanaka et al. BMC Pediatrics(2019) 19:162

The CT images were assessed by a respiratory organ
specialist (A.U.) and pediatrician (T.K.). They had morethan 20 years of clinical experience and were blind to
the FEES results. When their assessments did not match,they both re-evaluated the images and discussed them
until a consensus was reached. When assessment of animage was difficult because of artifacts in the images
resulting from a patient’s inability.
to control body movement during imaging, the participants were excluded (n = 5). Based on the method described by Butler et al. [14], the images were assessed forparenchymal bands, bronchiolectasis, bronchial wall
thickening, bronchiectasis, atelectasis, tree-in-bud pattern, intraluminal airway debris, fibrosis, and air trapping. Participants with any of these CT findings wereconsidered as having pneumonia.
Data analysis

The aspiration and nonaspiration groups were compared forhistory of pneumonia and chest CT findings of pneumonia.

Page 3 of 7

tree-in-bud pattern (eight [9.4%] participants), intraluminal airway debris (four [4.7%] participants), and otherfindings (four [4.7%] participants).
In the food aspiration/nonfood aspiration groups, 5/1(10.4%/2.7%) participants had parenchymal bands; 13/14(27.1%/37.8%) participants, bronchiolectasis; 27/19(56.3%/51.4%) participants, bronchial wall thickening; 1/1(2.1%/2.7%) participant, bronchiectasis; 11/6 (22.9%/
16.2%) participants, atelectasis; 4/4 (8.3%/10.8%) participants, tree-in-bud pattern; 4/0 (8.0%/0%) participants,
intraluminal airway debris; and 2/2 (4.0%/5.9%) participants, other findings.
In the saliva aspiration/non-saliva aspiration groups,
2/4 (7.7%/6.8%) participants had parenchymal bands; 11/
16 (42.3%/27.1%) participants, bronchiolectasis; 20/26(76.9%/44.1%) participants, bronchial wall thickening; 0/2(0/3.4%) participants, bronchiectasis; 9/8 (34.6%/13.6%)
participants, atelectasis; 1/7 (3.9%/11.9%) participants,
tree-in-bud pattern; 3/1 (11.5%/1.7%) participants, intraluminal airway debris; and 3/1 (11.5%/1.7%) participants,
other findings (Table 1).

Statistical analysis

Correlations between aspiration and history of pneumonia and between aspiration and CT findings of pneumonia were examined using the chi-square test or Fisher’s
exact test. The influence of aspiration on CT findings ofpneumonia was examined using logistic regression analysis in which aspiration was the independent variable
and the various CT findings of pneumonia were thedependent variables. Forced entry of age and sex as themoderator variables was used for multivariate analysis. All
tests were two-tailed. The significance level was p < 0.05.
Missing values were not supplemented in the analysis.
Outlier and extreme values were not excluded. Data wereanalyzed using SPSS version 22.0 for Windows (IBMJapan, Tokyo, Japan).

Results
Aspiration and history of pneumonia

Among 85 participants, the FEES findings revealed foodaspiration in 48 (56.5%) participants, saliva aspiration in
26 (30.6%) participants, and both food and saliva aspiration in 20 (23.5%) participants. Among 54 participants
with aspiration, 40 (74.1%) participants had silent aspiration. History of pneumonia within 1 year was observedin 33 (38.8%) participants.
Chest CT findings

The CT image analysis revealed signs of pneumonia in
54 (63.5%) of 85 participants. The CT image findings
were parenchymal bands (six [7.1%] participants),
bronchiolectasis (27 [31.8%] participants), bronchial wall
thickening (46 [54.1%] participants), bronchiectasis (two[2.4%] participants), atelectasis (17 [20.0%] participants),

Correlation between aspiration and history of pneumonia
and between aspiration and chest CT findings ofpneumonia

A history of pneumonia, based on medical records fromthe previous year, was not correlated with the presence orabsence of food or saliva aspiration (Table 2; p = 0.545 andp = 0.964, respectively). Food aspiration and chest CT
findings of pneumonia were not correlated (p = 0.120).
However, a significant correlation was observed with saliva
aspiration (Table 3, p < 0.01). Logistic regression analysis
revealed that saliva aspiration had a significant effect on
bronchial wall thickening (odds ratio [confidence interval]:
4.231 [1.485–12.055]) and atelectasis (odds ratio [confidence interval]: 3.375 [1.124–10.131]). Multivariate logistic regression analysis with age and sex included as themoderator variables revealed similar effects. By contrast,
food aspiration did not have a significant effect on any
finding (Table 4).

Discussion
Assessment with FEES

We used FEES to assess aspiration in this study. The
gold standard methods for evaluating swallowing functions are FEES and VFSS. Their detection rates of aspiration do not have a significant error [19, 20], and they
are useful in children and adults [21–23]. In our findings, 56% of the tested participants had aspiration, which
did not substantially differ from the results in previous
research [1]. Furthermore, 74% of the participants withaspiration exhibited silent aspiration. This finding is
consistent with that of another report [5] demonstrating

Tanaka et al. BMC Pediatrics(2019) 19:162

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Table 1 Chest CT findings as indicators of aspiration status
Food Aspiration

Saliva Aspiration

Aspirator(n = 48)

Nonaspirator(n = 37)

Aspirator(n = 26)

Nonaspirator(n = 59)

Chest CT findings
Parenchymal band5(10.42)1(2.70)2(7.69)4(6.78)Bronchiolectasis

13(27.08)

14(37.84)

11(42.31)

16(27.12)

Bronchial wall thickening

27(56.25)

19(51.35)

20(76.92)

26(44.07)

Bronchiectasis1(2.08)1(2.70)0(0)2(3.39)Atelectasis

11(22.92)

6(16.22)9(34.62)8(13.56)

Tree-in-bud pattern4(8.33)4(10.81)1(3.85)7(11.86)

Intraluminal airway debris4(8.33)0(0)3(11.54)1(1.69)Other findings2(4.17)2(5.41)3(11.54)1(1.69)The data are presented as the number (percentage) of participants.
CT, computed tomography.

that silent aspiration was common among patients withaspiration. This finding in the present study indicatedthat using an FEES study is valid for assessing aspiration.
A contrast agent is unnecessary in FEES; therefore,food that is eaten normally can be used as the test food.
Another major advantage of FEES is that aspiration canbe confirmed, despite the absence of contrasted saliva,
secretions, or other matter. Our results showed that,compared with food aspiration, saliva aspiration detectedby FEES was correlated with inflammatory findings in
the lungs. This finding indicated that FEES, which is able
to assess saliva aspiration, is a useful swallowing function test.
CT assessments

In the present study, CT was used to evaluate inflammatory findings in the lungs; CT involves more radiation
exposure and takes longer to conduct than does chest
radiography and requires that body movements becontrolled for a certain amount of time. Despite these issues, CT can detect dorsal and asymptomatic inflammatory findings. On account of its superior ability indetecting early stage lung changes and inflammatory
findings, we considered it as the optimal method tocarefully examine the relationship between aspirationand chest findings. Furthermore, for the current study,

chest CT was conducted in a medical center that specializes in the care of disabled children. This center has
specialized staff who are accustomed to interacting withdisabled children and technicians who routinely image
such patients. Therefore, except for the few patients who
were excluded, we obtained images with sufficient precision for the assessments.
Pneumonia history and food aspiration detected by FEES

A history of pneumonia in the previous year was notcorrelated with the presence or absence of food or saliva
aspiration. Weir et al. [24] examined the relationship between pneumonia history and the presence or absenceof food aspiration (detected by VFSS) in children. The
authors found a low correlation between food aspiration
detected by VFSS and history of pneumonia, based on
the World Health Organization definition, in the year
before VFSS [24]. We used FEES but not VFSS to evaluate aspiration, but our results were similar to those of
Weir et al. [24]. However, pneumonia was determinedbased on clinical symptoms such as fever or confirmed
in medical records; therefore, a variation in the diagnoses could have affected the accuracy of the assessments.
Furthermore, because the time difference between theaspiration assessment and the onset of pneumonia was
as much as 1 year, the assessments could have been

Table 2 Comparison of the history of pneumonia between aspirators and non-aspirators
Food aspiration

p-value

Aspirator(n = 48)

Non-aspirator(n = 37)Yes

20 (41.67)

13 (35.14)

No

28 (58.33)

24 (64.86)

p-value

Saliva aspiration
Aspirator(n = 26)

Non-aspirator(n = 59)

10 (38.46)

23 (38.99)

16 (61.54)

36 (61.01)

Pneumonia
0.545aThe data are presented as the number (percentage) of participants.
a
The p-value, based on the Pearson’s chi-squared testb
The p-value, based on the Fisher’s exact test

0.
655b

0.964a> 0.999b

(2019) 19:162

Tanaka et al. BMC Pediatrics

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Table 3 Comparison of chest CT findings between aspirators and non-aspirators
Food aspiration

p-value

Aspirator(n = 48)

Non-aspirator(n = 37)Yes

34 (70.83)

20 (54.05)

No

14 (29.17)

17 (45.95)

Saliva aspiration

p-value

Aspirator(n = 26)

Non-aspirator(n = 59)

23 (88.46)

31(52.54)

3 (11.54)

28 (47.46)

Pneumonia
0.111 a0.120 b0.002a> 0.001b

The data are presented as the number (percentage) of participants.
a
The p-value, based on the Pearson’s chi-squared testb
The p-value, based on the Fisher’s exact test
CT, computed tomography; RC, regression coefficient; OR, odds ratio; 95% CI, 95 confidence interval; n.c., not calculated.

affected by other factors that may have appeared between the onset of pneumonia and the assessment (e.g., afood-related intervention or onset of a different disease).
Therefore, to examine the relationship between aspiration
detected during testing and pneumonia, we used chest CT
findings, which are associated with little diagnostic variation, and FEES performed within 1 week after CT.

does not necessarily represent a risk of pneumonia in
disabled children. In addition, regarding food aspiration,
our findings suggested that it is necessary to consider
not only the presence or absence of aspiration, which isthe conventional evaluation standard, but also theamount and frequency of aspiration.
Saliva aspiration and chest CT findings of pneumonia

Food aspiration and chest CT findings of pneumonia

In the present study, we examined the relationship between the presence or absence of aspiration detected by
FEES, and the presence or absence of pulmonary inflammation in the chest CT image obtained within 1 week
before FEES (inclusive of the day of the test). Comparedwith findings in previous studies [6, 7, 9, 12–14, 24] thatexamined aspiration (detected by testing) and history ofpneumonia, the present study had little time difference
between the swallowing function test and the chest
evaluation, which indicated the swallowing function at
the time of the test was compared with the state of thelungs. Thus, food aspiration detected by testing was notcorrelated with inflammatory findings on chest CT. The
study by Butler et al. [14] involved an older population
and CT timing, and revealed no correlation between
food aspiration detected by FEES and inflammatory findings in chest CT conducted within 1 year of the test. Ourfindings were derived from children; however, they support the findings of Butler et al. [14]. Thus, our findings
suggested that food aspiration detected during testing

We observed a significant correlation between saliva aspiration and chest CT findings of pneumonia. Furthermore, in a multivariate logistic regression analysis using
age and sex as the moderator variables, saliva aspiration
detected during testing was significantly correlated withthe chest CT findings of bronchial wall thickening andatelectasis. Thus, CT may detect inflammatory changesof the lungs at an early stage. We observed atelectasis
and bronchial wall thickening, which presumably occur
because of repeated aspiration and inflammation of thebronchi caused by aspiration [25, 26]. In the present
study, we used the advantages of FEES to examine, without contrast, the aspiration of food or other secretions
such as saliva in the pharynx. Furthermore, to minimize
stimulation of the oral cavity induced by test food ingestion or by inserting the endoscope, saliva aspiration was
immediately assessed after inserting the endoscope andbefore the ingestion of the test food. Therefore, saliva aspiration detected by the test may reflect a chronic decrease in swallowing function or may reflect regularly
occurring aspiration. In fact, 77% of participants who

Table 4 Relationship between saliva aspiration and chest CT findings
Univariate logistic regression analysis
Parenchymal band

Multivariate logistic regression analysis (adjusted for age and sex)RCOR

95% CI

p-valueRCOR

95% CI

p-value

0.136

1.146

0.196–6.685

0.880

0.206

1.229

0.202–7.465

0.823

Bronchiolectasis

0.678

1.971

0.749–5.182

0.169

0.687

1.987

0.737–5.361

0.175

Bronchial wall thickening

1.442

4.231

1.485–12.055

0.007

1.645

5.182

1.663–16.151

0.005

Bronchiectasisn.c.

Atelectasis

1.216

3.375

1.124–10.131

0.030

1.210

3.353

1.088–10.334

0.035

Tree-in-bud pattern−1.2140.297

0.035–2.548

0.268−1.2360.291

0.034–2.501

0.261

Intraluminal airway debris

2.024

7.565

0.748–76.507

0.087

1.961.

7.107

0.673–75.020

0.103

n.c.

CT, computed tomography; RC, regression coefficient; OR, odds ratio; 95% CI, 95 confidence interval; n.c., not calculated.

Tanaka et al. BMC Pediatrics(2019) 19:162

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exhibited saliva aspiration also had food aspiration. Link
et al. [27] reported that larger secretion pools were associated with an increased incidence of aspiration pneumonia in children. In another study [28], the researchers
demonstrated that the extent of the pooling of secretionsin the laryngopharynx was predictive of aspiration.
These findings indicated that the presence or absence ofsaliva aspiration detected immediately after endoscope
insertion could be used to predict pneumonia risk.
In the present study, the PAS was used as the assessment criterion for swallowing function, along with FEES
and VFSS. However, this scale evaluates the presence orabsence of aspiration from a few mouthfuls of test foodingested at the test venue; thus, it does not reflect theamount of aspiration normally present, the content ofaspirated matter (i.e., apparent or silent), or the possibility of expectorating the aspirated matter. The PAS is an
excellent indicator of swallowing function; however, it
may be insufficient when considering pneumonia as an
outcome. It may also be necessary to evaluate saliva aspiration, as well as the test food. The findings of thepresent study indicated that the management of swallowing dysfunction that is based only on the presence offood aspiration may result in excessive restriction or
stopping of oral feeding, which may not allow an individual to maintain or develop swallowing function or
may result in overmanagement that harms an individual’s food-related quality of life. Further investigations
focusing on how to interpret swallowing function tests
are needed.

In order to avoid missing saliva aspiration as much as
possible, measures were taken, such as securing an appropriate field of view at the time of evaluation and confirmation of findings by multiple evaluators. However,the possibility of missing saliva aspiration is a limitationof this study.
We examined whether the presence or absence of aspiration during testing was associated with chest CT
findings of inflammation and history of pneumonia in
disabled children. Pneumonia history was not correlatedwith the presence or absence of food aspiration or withpulmonary CT findings. By contrast, the presence of saliva aspiration was significantly correlated with the pulmonary CT findings of bronchial wall thickening andatelectasis. When evaluating the swallowing function of
disabled children, it may be difficult to assess risk ofpneumonia by only examining food aspiration, whereas
the presence or absence of saliva aspiration could indicate such a risk. Furthermore, our results suggest theneed for new benchmarks to evaluate pneumonia risk,such as the assessment of the type or amount of aspirated matter.

Limitations

Abbreviations
CT: computed tomography; FEES: fiberoptic endoscopic evaluation ofswallowing; PAS: penetration-aspiration scale; VFSS: videofluoroscopic
swallowing study

The participants of this study were children with developmental disabilities who were unable to understand or
follow instructions during CT. Therefore, it was impossible for them to control their body movements or maintain maximum inspiration during imaging. The imaging
conditions were less than ideal; therefore, unrevealed
findings may exist. To address this possibility, we excluded
five participants whose images contained artifacts becauseof body movement or were otherwise difficult to interpret.
By only evaluating participants whose images the assessors
could interpret, we avoided lowering the precision of theimage evaluations as much as possible.
In this study, it could not be determined whether thepneumonia was caused by aspiration or community
acquired-infection. It was difficult to accurately diagnose
whether the pneumonia was due to aspiration. However,1) all subjects had swallowing impairment; and 2) all CT
findings examined in this study were inflammatory findings due to aspiration. Based on these findings, the probability of pneumonia having been caused by aspiration isquite high in the subjects of this study.

Conclusions
The results of the present study show that among children, risk assessment of pneumonia based only on thepresence or absence of food aspiration detected by swallowing function tests may miss significant saliva and secretion aspiration. Moreover, the status of saliva aspiration
may be an indicator of aspiration pneumonia risk and may
be useful in the management of dysphagia.

Acknowledgements
We would like to thank the staff of the Osaka Developmental Rehabilitation
Center (Osaka, Japan), as well as its patients and their families. We express
our sincere gratitude for their assistance. We would like to thank Editage(http://www.editage.jp/) for English language editing.
Funding
This study was funded by a scientific research grant from the Japan Society
for the Promotion of Science (Tokyo, Japan; grant number: 17 K12007).
Availability of data and materials
The datasets used and analyzed during the current study are available fromthe corresponding author on reasonable request.
Authors’ contributions
NT, KN, and TS designed the study; AU and TK contributed to the analysis
and interpretation of the data, especially chest CT findings; and NT, MU, andNF contributed to the analysis of the swallowing evaluation data. All otherauthors have contributed to the data collection and interpretation, andcritically reviewed the manuscript. All authors read and approved the final
manuscript, and agree to be accountable for all aspects of the work and inensuring that questions related to the accuracy or integrity of any part of
the work are appropriately investigated and resolved.

Tanaka et al. BMC Pediatrics(2019) 19:162

Ethics approval and consent to participate
All procedures performed in studies involving human participants were inaccordance with the ethical standards of the institutional and/or national
research committee and with the 1964 Helsinki declaration and its later
amendments or comparable ethical standards. This study was approved by
the Osaka Developmental Rehabilitation Center ethics committee (Osaka,
Japan; approval no.: H26–11).
Written informed consent was obtained from the parents or guardians of allparticipants included in the study.
Consent for publication
Not applicable.
Competing interests
The authors declare that they have no competing interests.

Publisher’s NoteSpringer Nature remains neutral with regard to jurisdictional claims inpublished maps and institutional affiliations.
Author details
1
Division of Oral and Facial Disorders, Osaka University Dental Hospital, 1-8,
Yamadaoka, Suita, Osaka 565-0871, Japan. 2Division of Functional Oral
Neuroscience, Graduate School of Dentistry, Osaka University, Osaka, Japan.
3
Medical Corporation Toujinkai, Fujitate Hospital, Osaka, Japan. 4Osaka
Development Rehabilitation Center, Osaka, Japan.
Received: 24 November 2018 Accepted: 8 May 2019

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