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.