Forty per cent of children with bronchomalacia had an early expiratory peak with the concave expiratory limb. Tracheomalacia was present in 13 children (in seven associated with laryngomalacia and in six associated with laryngomalacia and bronchomalacia), and six out of these had flattened expiratory limb (in three only flattened expiratory limb, the pattern two and in three associated with fluttered inspiratory limb, the pattern 4). One child with pharyngomalacia had a normal IPFT pattern (pattern 1). Children with subglottic stenosis had a flat expiratory limb in 3 out of 4. The representative patterns are shown in Figure 3.