Dear Editor:
We read the original article High-flow nasal cannula for the treatment
of life-threatening plastic bronchitis published on your
journal1. This article suggests that the use of home
high‐flow nasal cannula (HFNC) may be a viable therapy for
life‐threatening plastic bronchitis. As the authors say in the article,
treatment options for plastic bronchitis are limited and not always
effective. Authors defend that using HFNC could generate positive
intra‐airway pressure that might counteract the dilatation of pulmonary
lymphatics, and therefore, the bronchial cast formation. We would like
to report a case of a patient requiring chronic mechanical ventilation
with life‐threatening upper airway obstruction due to bronchial casts.
We report the case of a 19-month-old boy admitted to the cardiology ward
with a significant past medical history for levo-transposition of great
arteries with double outlet right ventricle for which the patient had
undergone multiple surgical interventions including a pulmonary artery
banding and a
bidirectional
superior vena cava to pulmonary artery shunt (Glenn procedure) at seven
months old. Failure of the Glenn circulation with reverse blood flow
through the shunt was observed with low cardiac output and development
of venous collateral circulation (Figure 1A) . Other postoperative
complications included an atrioventricular blockage requiring pacemaker,
chronic mechanical ventilation through tracheostomy, and massive
chylothorax in the immediate postoperative period, followed by prolonged
hospital course due to medical complexity from failed Glenn circulation.
Twelve months following the Glenn procedure, he suffered an episode of
respiratory distress, with decreased oxygen saturation and coughing
fits, coinciding with generalized swelling and one kilogram weight gain
in the last days. Two of the fits ended up with spontaneous
expectoration of bronchial casts (figure 1B ).
He was transferred to the Pediatric Intensive Care Unit (PICU) where
nebulized treatment with bronchodilators, tissue-type recombinant
plasminogen activator (rTPA) and oral azithromycin was initiated as
treatment for plastic bronchitis. The diuretic treatment was also
optimized.
The patient experienced an initial improvement but 12 hours later he
developed an episode of severe respiratory distress, with persistent
desaturation to 50-60% SpO2 despite manual ventilation. A chest
radiography showed complete left lung collapse with right lung
infiltrates. An urgent flexible bronchoscopy (FB) was performed,
removing several rubbery white casts by suction and bronchoalveolar
lavage with a mixture of rTPA and saline solution with improvement and
increase of the oxygen saturation.
In the following days, treatment with nebulized rTPA and later with
nebulized heparin was initiated. Pulmonary circulation was optimized
with pulmonary vasodilators including inhaled nitric oxide and inhaled
prostaglandin added to his previous treatment with bosentan and
sildenafil. Follow-up FB were performed, without finding more bronchial
casts.
Three
cardiac
catheterization procedures were performed during the following weeks in
order to optimize hemodynamics: obstruction of the superior venous
circulation was detected, without identifying any thrombosis in the
Glenn circuit; the venous collateral circulation was obliterated; a
stent was placed in the atrioventricular septum; and two stents were
placed at the pulmonary banding in order to reduce the pressure gradient
through the Glenn.
The patient was discharged two months later under continued heart
failure management, bronchodilators, pulmonary vasodilators and
nebulized hypertonic saline. During the following months, the patient
presented occasionally with spontaneous bronchial cast expectoration but
without respiratory distress or new plastic casts finding in repeated
FB. However, he recently required a new admission at the PICU due to a
new episode of respiratory distress requiring additional FB and cardiac
catheterization procedure in order to optimize hemodynamics.
Plastic bronchitis is an uncommon condition consisting of obstruction of
the airway by bronchial thick, rubbery, white casts. It is diagnosed
after its expectoration or direct visualization during a
FB2 Patients present with respiratory symptoms such as
cough, dyspnea and respiratory distress. Although there are some
specific tests such as the dynamic contrast magnetic resonance
lymphangiography for the visualization of lymphatic abnormalities, most
radiologic images are non-specific for this condition being common the
presence of signs of bronchi obstruction.
The etiology is multifactorial with the influence of inflammation and an
excessive permeability of the alveolocapillary membrane, mainly due to
venous and lymphatic stasis that occurs after critical congenital heart
disease surgeries. It is a rare complication in patients after Glenn
shunt, more commonly reported after Fontan’s surgery3with a prevalence of 14-23% and a mortality rate up to
38%4. Viral infections and inflammatory pulmonary
diseases like asthma are also uncommon causes of plastic
bronchitis3. In our case, the patient presented with
fluid overload in the days prior to the acute episode that could have
increased the lymphatic pulmonary stasis in a patient with an underlying
complex congenital cardiopathy, predisposing the casts formation.
Treatment of the acute condition consists of FB bronchoalveolar lavage
and casts suction, with the addition in some cases of the administration
of a fibrinolytic agent via FB. Other treatment options that have been
described to improve the symptoms include the use of nebulized heparin
and rTPA. There is not enough clinical evidence to support any of these
treatments, but reports suggest that heparin has more anti-inflammatory
effects, less vascular bleeding risk2, and
significantly reduced treatment costs5, which were the
reasons that motivated the change from rTPA to heparin in our case.
In recent years, another treatment based on the pathophysiology of the
disease has gained relevance: the selective embolization of the thoracic
duct that would interrupt the extravasation of the lymph and, therefore,
the formation of bronchial casts. Although previous results are
encouraging6, this therapy was not attempted in our
patient as lymphatic canalization was previously unsuccessful to control
a high output chylothorax.
Nevertheless, definitive treatment is based on improving the underlying
condition, which can be challenging in this type of patients. In
patients with congenital heart disease, a good cardiac output must be
achieved, optimizing the hemodynamic condition by using pulmonary
vasodilators, administering drugs to reduce the cardiac preload, or by
performing surgical/interventional procedures as previously discussed.
In conclusion, plastic bronchitis is an uncommon disease but with poor
prognosis as it represents a threat of airway obstruction and asphyxia.
Therefore, it is important to include it in the differential diagnosis
of respiratory distress, particularly in patients with underlying
pathologies predisposing to this condition. Early treatment includes
bronchial lavage through FB but definitive treatment is based on
improving the underlying condition, a challenge in these patients.