Methods
We performed a prospective cohort study from July 2018 to April 2020 in
children from 0-2 years with physician suspected airway anomalies. We
suspected airway anomalies in the presence of either persistent (more
than two weeks) inspiratory or biphasic (both inspiratory and
expiratory) stridor or children with persistent (more than two weeks)
barking or brassy cough or children with unexplained wheezing that is
not responding to inhaled steroids for 4-8 weeks with proper compliance
and technique or choking while feeding without significant developmental
delay. We excluded children with hypoxia (SpO2 <92%),
hemodynamic instability, naso-facial deformities, tracheostomy and
pulmonary bleed. We recorded detailed history, physical examination and
baseline data of all enrolled children. Then these children underwent
IPFT and bronchoscopy. The two investigations were done within a week of
each other. The person doing the IPFT was not aware of bronchoscopy
findings if bronchoscopy was done earlier.
The IPFTs (TBFVL) were done during sleep or light sedation by
trichlophos single dose of 50 mg/kg. TBFVL was performed in the
pulmonary function test lab with EXHALYZER-D equipment (ECO MEDICS,
Duernten, Switzerland) having Spiroware-1 software. Bronchoscopy was
performed as per unit protocol under conscious sedation. Three observers
(SKK, KRJ, AP) independently reported abnormalities and severity after
seeing the saved bronchoscopy video. IPFT were also reported by three
observers blindly, and in case of discrepancy, the final diagnosis was
made by discussion.
Patterns and parameters of IPFT were compared with findings of
bronchoscopy. We categorized the IPFT curve into the following five
patterns, as shown and explained in Figure 1, modified from the study by
Filippone et al. (5).