may edition file

size assessment may be unfamiliar.
The mechanisms of action and optimal
patient selection need to be addressed
in further rigorous clinical and scientific
studies.
Indications
Candidates for bronchial thermoplasty
include adults with severe persistent
asthma who require regular
maintenance medications of inhaled
corticosteroids (>1000 µg/day of
beclomethasone or the equivalent) and
a long-acting beta agonist (≥100 µg/
day of salmeterol or the equivalent).
These patients would have received
add-on therapies such as leukotriene
modifiers, omalizumab, or oral
corticosteroids (≤10 mg/day).
These patients should be on stable
maintenance asthma medications
according to accepted guidelines,
should have a pre-bronchodilator
forced expiratory volume in 1 second
(FEV1) of 60% or more of predicted,
and should have a stable asthma
status (FEV1 within 10% of the best
value, no current respiratory tract
infection, and no severe asthma
exacerbation within the preceding 4
weeks).
Patients are usually selected
on the basis of the AIR 2 trial. The
patient should be stable in terms
of asthma status, defined as a post
bronchodilator FEV1 within 15% of
baseline values with no respiratory
tract infection or asthma exacerbations
within the preceding 14 days.
Contraindications
Contraindications for BT include the
following:
• Presence of an implantable
electronic device
• Known hypersensitivity to drugs
used during bronchoscopy
• Severe comorbid conditions that
would increase the risk of adverse
events
Patients are not considered
candidates for BT if they had three or
more hospitalisations for asthma, three
or lower respiratory tract infections and
four or more oral corticosteroids used
for asthma in the previous year.
Although the benefits of BT may
be large, the potential harm may be
large as well, and the long-term side
effects are unknown. Studies are still
needed to assess exacerbation rates
and long-term effects on lung function.
It remains to be determined which
phenotypes will respond best to BT,
what the effects may be on obstructed
patients with an FEV1 higher than
60%, and what the applicability of the
procedure may be in patients receiving
systemic steroid therapy
Procedure considerations
BT is performed via fibreoptic
bronchoscopy in three separate
procedures, separated by
approximately 3 weeks, as
PATIENTS ARE NOT
CONSIDERED CANDIDATES
FOR BT IF THEY HAD THREE
OR MORE HOSPITALISATIONS
FOR ASTHMA
demonstrated by previous studies.]
Dividing the treatments into three
bronchoscopy sessions minimizes
the risk of inducing an asthma
exacerbation or diffuse airway oedema.
It also avoids excessive procedural
length. BT takes longer (30-60
minutes) than a standard fiber-optic
bronchoscopy (5-20 minutes) does,
and the longer duration implies the
use of larger doses of medication for
sedation.
All accessible airways are treated,
with the exception of the right middle
lobe, because of the theoretical
concern about the risk of inducing
right-middle-lobe syndrome.]
Oxygen delivery should be started
via a nasal or oral cannula during
the procedure, with appropriate
monitoring of vital signs. Heart rate,
pulse oximetry, and noninvasive blood
pressure should be continuously
monitored.
Outcomes
Patients may experience respiratoryrelated
adverse events such as cough,
wheezing, and chest tightness during
the treatment period. Most of these
symptoms occur within 1 day of the
procedure and resolve in an average of
7 days with standard therapy.
It is unclear why an intervention
aiming at a reduction of smoothmuscle
mass would not affect
FEV1. Given that the number of
exacerbations is reduced with no
change in FEV1, it may be that altered
response to the inflammatory triggers
plays a role in addition to the reduction
in smooth-muscle mass.
Complications
Recurrent lung atelectasis secondary
to fibrin plugs has been reported
as an early complication of BT.
In the susceptible patient, high
thermal stimulation may lead to
an inflammatory reaction with
microvascular alteration, induced
either by heat or by the release of
inflammatory mediators. Lung abscess
has also been described as a direct
complication; thus, collecting and
publishing safety data continue to
be important. A prospective cohort
study performed as part of the
TASMA trial reported a high incidence
of acute radiologic abnormalities
after BT. Postprocedural CT of
the chest identified four different
radiologic patterns: (1) peribronchial
consolidations with surrounding
ground-glass opacities (94%), (2)
atelectasis (38%), (3) partial bronchial
occlusions (63%), and (4) bronchial
dilatations (19%). These complications
resolved without clinical impact in
virtually all cases.
The author is Head, Department of
Respiratory Medicine, Medical Trust
Hospitals, Cochin
May 2019 / FUTURE MEDICINE / 31