Results
A total of 54 PDO stents were placed in 26 patients during the study
period and 14 (53.8%) required more than one stent for management
(median, 2 stents). The cohort was constituted by 14 boys and 12 girls
with a median age of 4 months [IQR 3-7] when the first stent was
placed. The youngest patient in our series was 2 months of age and the
lowest weight was 3 kg, while the oldest was 6 years of age and 20 kg.
All patients showed severe symptoms of airway obstruction due to one of
the following diseases: tracheomalacia (TM, 9 patients), bronchomalacia
(BM,5), tracheobronchomalacia (TBM, 10) and postsurgical tracheal
stenosis (TS, 2 cases). As shown, congenital airway malacia was the most
frequent disease causing central airway obstruction (92.3%): 13
(54.1%) corresponded to primary malacia and 11 showed airway collapse
secondary to extrinsic vascular compression. Respiratory clinical status
when airway stenting was as follows: 14 patients had a tracheostomy for
ventilatory support, 3 were intubated and ventilated, non-invasive
ventilation was required in 5, oxygen therapy in 3 and one patient
showed recurrent respiratory infections requiring hospitalization.
Endoscopical placement of PDO stents was uneventful in every patient. In
some cases minor readjustements with a semirigid 1mm alligator forceps
were performed in order to accurately match the lesion. Balloon dilation
of the stent was deemed necessary in 22 stents (40.7%) in order to
immediately achieve the nominal diameter and expected radial force.
Median stent diameter and length were 7 mm (IQR 5-9) and 22.5 mm (IQR 15
– 35) respectively. Regarding anatomic location, 29 stents (53.7%)
were placed in the trachea and 25 in the main bronchi (7 right and 18
left) (figure 1). All patients showed severe comorbidities being
cardiovascular anomalies most frequent (65.3%). Ten patients (38.4%)
exhibited more than one associated anomaly including genetic syndromes
(Table I).
Clinical respiratory status achieved after stent placement was the main
outcome measure in our study. According to the previously mentioned
cathegorization, 8 (30.7%) patients showed complete resolution of their
symptoms and 13 (50%) partial clinical improvement. Airway stenting did
not have an impact on the clinical condition of 4 patients (15.3%) and
in one (3.8%) it became even worse due to stent-related complications.
Additionally, we evaluated the potential contribution of the collected
variables to the four different clinical outcomes observed. Analysing
those patients with complete resolution of their respiratory symptoms
after stenting and comparing them to the other 3 groups with a different
clinical outcome (partial improvement, unchanged, worsen), we observed
that age had significantly positive impact (6 months vs 3 m; p=0.024)
(Table II). Moreover, putting together patients with complete or partial
improvement and comparing them to those with no change or clinical
deterioration, we observed that a smaller PDO stent was associated with
a better outcome (median length, 20 vs 26 mm; p=0.044) (Table III).
Granulation tissue formation was the most frequent stent related
complication observed in our study. Because PDO stents represent a
foreign body in the airway, some minor degree of granulation tissue
formation is usually expected (fig. 2). Nevertheless, granulation tissue
requiring a bronchoscopic procedure in order to remove it with forceps,
ballooning or laser, was a relevant issue observed in 34.6% (9/26) of
our cases (5 tracheal and 4 bronchial) (fig. 3). Mean size of tracheal
stents causing granulation was 23 x 7.6 mm, while bronchial stents were
18.7 x 5.2 mm. These patients were more prone to accumulate secretions
needing aspiration and lavage when bronchoscopy was performed.
Additionally, stent migration was observed in one case (oldest patient)
due to a mismatch between the stent size and the lesion, and severe
tracheal stenosis in another requiring surgical resection and Montgomery
T-tube insertion. No bleeding, infection or airway erosion were detected
in the cohort. No patients showed difficulties in coughing or expelling
stent fragments during biodegradation. One stent was too long and we
decided to cut it to match the bronchial malacic lesion. This proved to
be a wrong decision so it was removed and a new one ordered. In another
case of BM the stent was too short to give effective support so it was
removed and replaced by a longer one. Stent surveillance relied mainly
on clinical assessment. Due to our institutional wide availability for
bronchoscopic exploration, FB was immediately performed by our team if
deemed necessary.
Five patients (19.2%) died during follow-up due to severe associated
anomalies: two with polymalformative syndromes and 3 with complex
congenital cardiopathy with pulmonary hipertension or sepsis (2
patients). Currently, no ventilatory support is required in 14 patients
(53.8%), 5 (19.2%) carry a tracheostomy without assistance and 2 more
patients have a tracheostomy with intermitent ventilatory support.
Median follow-up was complete with a median value of 58 months [IQR
12-77].