Figure1: Five Patterns of IPFT curve. Pattern1- Normal TBFVL
graphic curve; Pattern 2- Normal inspiratory limb and FLATTENED
expiratory limb of TBFVL curve; Pattern 3- Normal expiratory limb and
FLUTTERED inspiratory limb of TBFVL curve; Pattern 4- Inspiratory limb
FLUTTERED and expiratory limb FLATTENED; Pattern 5- Early expiratory
peak with the concave expiratory limb.
IPFT parameters evaluated were: tidal volume, inspiratory time (Ti),
expiratory time (Te), Ti/Te, respiratory rate, peak tidal inspiratory
flow (PTIF), peak tidal expiratory flow (PTEF), the ratio of PTEF/PTIF,
time to PTIF, time to PTEF, time to peak tidal expiratory flow/total
time to expiration (t_PTEF /t_ E), and the ratio of mid-tidal
expiratory flow to mid-tidal inspiratory flow (MTEF/MTIF). For controls
for this study, we extracted data for a similar number of age (±1
month), gender and birth weight-matched healthy controls from the birth
cohort study database from another project of our department. (6)
Enrolled children were followed six months after enrolment. Clinical
details were recorded, and a repeat IPFT was conducted. Bronchoscopy was
not repeated at six months follow-up. For follow-up controls, IPFT of
the same children matched earlier were taken after six months. The
primary outcome measure was a graphic pattern of TBFVL in children with
laryngomalacia. Secondary outcome measures were bronchoscopy diagnosis
of various airway anomalies, graphic pattern in children with airway
anomalies other than laryngomalacia, measurement of TBFVL parameters and
measurement of change in TBFVL graphic patterns and parameters at six
months follow up.
The pattern of IPFT loops and type of airway anomalies were analyzed by
simple frequency as a percentage. TBFVL parameters were compared among
historical controls and various bronchoscopy airway anomalies. If data
were symmetrically distributed, we applied a t-test. When there was
asymmetrical distribution, we used the Mann-Whitney test. ANOVA was used
to compare differences between two or more means. Changes in TBFVL
graphic patterns and parameters were analyzed after six months by paired
t-test. The data was recorded in an excel sheet, and statistical
analyses were done using STATA software version 12. Ethical clearance
was taken from the institutional ethical committee.