Key words
Plastic Bronchitis, Preterm Infant, Wheezing
More than 1 in 10 of the world’s infants was born prematurely. As the
second leading cause of death in children younger than 5 years of age,
prematurity remains a global health problem.
Prematurity followed with amnion
infection, growth restriction, oxygen toxicity, and volutrauma and
barotrama from mechanical ventilation may interrupt normal pulmonary
alveolarization and vascularization development and thus create a
clinical scenario of lung injury with pathophysiological effects that
can extend beyond infancy into adulthood1. Instead of
the eosinophil-mediated inflammation and atopy typical of asthma, the
survivors of preterm birth of recurrent broncho-obstructive symptoms
result from abnormal growth and development of the architecture of the
lung2. We describe a case of lung atelectasis due to
plastic bronchitis in a 26-month-old toddler who was born at
29+6 weeks gestational age.
A 26-month-old boy was admitted to our hospital in September, 2018, with
complaint of coughing for two days, fever and wheezing for one day.
Birth History
The patient was born at same hospital at 29+6 weeks gestation to a
31-year-old primigravid mother by cesarean section. His mother had got
preterm premature rupture of membranes (pPROM) for 22 days, and the
placental pathology after birth suggested mild stage I chorioamnionitis
(CAM). His birth weight was 1230g (50th percentile), the 1-minute and
5-minute Apgar scores were 8 and 9, respectively. He had spontaneous
breathing after birth and transferred from the operating room to the
neonatal intensive care unit (NICU) in a transfer shuttle supporting
with nasal continuous positive airway pressure (nCPAP). He was diagnosed
as transient tachypnea syndrome and received nCPAP for 24 days with
fraction of inspired oxygen (FiO2)<0.35.
During the first 72 hours after birth, the nCPAP level was kept within 6
cmH2O, then it was titrated to 4 to 5
cmH2O to achieve the lowest FiO2 level.
The boy was treated with cefoperazone sodium and sulbactam sodium for 10
days due to the suspected amnion infection. He was on nasogastric
feeding with own mother’s milk and premature infant formula,
supplemented partial parenteral nutrition in the first 25 days during
hospitalization. He was discharged on 36 weeks postmenstrual age (PMA)
with body weight 2260g (10th percentile).
Follow-up
The boy was followed in the healthcare center in our department. He had
moderate speed of catch-up growth (Figure 1). He had eczema since 5
months after birth, and upper respiratory tract infection 3 times during
infancy. He had suffered from repeated wheezing since 18-month-old and
diagnosed as bronchial asthma in other hospital. Since then, he had
received intermittent inhalation therapy with budesonide and
terbutaline. Four weeks before admission, he had an episode of wheezing
and thoracic radiograph showed bronchitis changes without other abnormal
findings.
After admission, full clinical examination including general, cardiac,
chest and abdominal was performed. On examination, the patient appeared
lethargy and slightly uncomfortable. The temperature was 38.6℃, the
heart rate was 155 beats per minute, the respiratory rate was 50 breaths
per minute, and the transcutaneous oxygen saturation
(SpO2) was 92% while breathing ambient air. Signs of
respiratory distress were observed and presence of inspiratory
retractions. Chest auscultation was done by the same physician during
the hospital stay. Abnormal auscultatory findings included diminished
breath sounds, bronchial breath sounds and fine crepitations in the left
lung, wheezing and crackles in the right lung. The remainder of the
examination was normal.
Results of laboratory tests are shown in Table 1. The white blood cells
count was normal with slightly increased neutrophils proportion. Liver
function and kidney function were normal. Arterial blood gas analysis
showed hypoxemia. Antibody quantification of mycoplasma pneumoniae was
negative.
After the patient was admitted, intravenous injection azithromycin
(10mg/kg) and methylprednisolone were administered. Supplemental oxygen
was given. The oxygen saturation ranged from 92 to 95 percent while the
patient was breathing 100 percent oxygen. Tachypnea persisted, with
minimal retractions and paroxysmal acute cough. A chest radiograph
revealed air trapping with hyperinflation in the right lung and
opacification of the left upper lobe representing atelectasis (Figure
2). He received inhaled budesonide 1mg, ipratropium bromide 250μg, and
terbutaline 2.5mg four times a day.
On the second day, a computed tomographic (CT) scan of the chest
confirmed superior lobe of left lung atelectasis, and the bronchial
openings of the upper and lower lobes disappeared (Figure 3). We
continued his atomization inhalation treatment
and started nebulized Nacetylcysteine (2.5mL 20% solution) twice a day.
The bronchoscopy was planned on the next morning.
The same night, after a severe cough, the patient expelled large casts,
sticky whitish secretions, shaping as the tracheobronchial tree (Figure
4). Inspiratory retractions were disappeared and the respiratory rate
slowed down to 30 breaths per minute. Coarse breath sounds were heard in
both lungs with fine crepitations and wheezing.
On the third day, chest-X ray reexamined normal permeability in both
lungs. Then the bronchoscopy was canceled. On the fifth day, the chest
auscultation was clear and the patient was discharged. He was
followed-up in the pediatric pulmonary
clinic.
This case shown the airway casts produced by a toddler with preterm
birth history and asthma. On physical exam, wheezing, decreased breath
sounds and respiratory distress were observed in this patient. After
treatment with inhaled budesonide, ipratropium bromide, terbutaline and
nebulized N-acetylcysteine, the patient spontaneously expectorated casts
without bronchoscopy.
Plastic bronchitis is an uncommon condition, characterized by the
formation of tracheobronchial airway casts, which are partially or fully
block the bronchial lumen. It is mainly associated with underlying
congenital heart disease or lung
diseases3. As to lung diseases, it has been associated
with asthma, allergic bronchopulmonary aspergillosis, mycoplasma
pneumoniae, influenza B virus infection and pulmonary tuberculosis, etc.
Clinically, patient with plastic bronchitis presents with dyspnea,
wheezing, or pleuritic chest pain, and may have fever. Chest x-ray and
CT findings are often non-specific including opacity or infiltrate.
The mechanism of casts’ formation remains unclear for the inflammatory
casts in lung disease. In patients with asthma, previous
studies hypothesis that the cause of casts is likely related to chronic
inflammation and its attendant neutrophilic and eosinophilic airway
infiltration, with decreased mucociliary clearance, the airways become
occluded with eosinophils and neutrophils in a mucinous background.
There have been several case reports of plastic bronchitis caused by
mycoplasma pneumoniae. In this case, four weeks before this acute
episode, the chest X-ray was normal, indicating the acute infection was
the precipitating factor. The disease onset was in the autumn with low
to moderate grade of fever. The blood routine examination was normal,
and the application of macrolide anti-infection was effective. Thus, we
consider the high possibility of mycoplasma pneumoniae infection in this
case, in spite of the antibody was negative which may result from the
earlier sample time on the third day of disease onset.
During the 24 to 38 weeks of gestation age,which is the saccular phase
of lung development, the relationships between the air spaces,
capillaries, and mesenchyme takes on more significance. The
alveolocapillary membrane is sufficient to participate in gas exchange
until approximately 24 weeks of gestation age. For the very low birth
weight infants (with birth weight less than 1500g) as this case or the
other, are at higher risk because they have very few vessels and alveoli
developed at birth. The pulmonary inflammatory response may have been
initiated in utero, in the setting of CAM. CAM is acute inflammation of
the membranes and chorion of the placenta, commonly due to ascending
polymicrobial bacterial infection, which leads to preterm premature
rupture of membranes (pPROM). The earlier and more serious the exposure
to chorioamnionitis is, the more immature and disrupted the lung
structure would be4. The initiation of inflammation
appears to cause impairment of the growth of alveoli and of the
microvasculature. The boy’s mother had got pPROM and chorioamnionitis,
which may disrupt the offspring’s lung alveolarization and
vascularization during infancy and childhood.
Pulmonary consequences of preterm birth tend to persist throughout the
life course. Recurrent wheeze in infants and toddlers is associated with
small airway calibre, low lung function and airway
inflammation5. In this case, the potential impaired
pulmonary function and the acute attack triggering by infection may play
important roles in the plastic bronchitis.
On the treatment3,flexible or rigid bronchoscopy is
most often used for cast removal. Other medication options include
aerosolized fibrinolytics, such as urokinase, and inhaled mucolytics,
such as acetylcysteine and dornase
alfa. Mucolytics appear to be more useful in inflammatory casts, as the
mucus contains. In those with lung diseases involving bronchial
hyper-reactivity, treatment is based on the use of inhaled and systemic
corticosteroids. In this case,the spontaneous expulsion of casts could
prove effectively more flexible plugs, and the inhaled N-acetylcysteine
also played a role6.
In conclusion, we present an exceptional case of a toddler born
prematurely provoked plastic bronchitis. In the recurrent attacks of
wheezing toddlers, the acute respiratory tract infection disturbs the
airway barrier and may induce bronchial plastics, especially in those
born prematurely.