Evaluation of the trachea and intrathoracic airways by the acoustic reflection method in children with cystic fibrosis

Tracheomalacia has been observed in older patients with cystic fibrosis (CF). The acoustic reflection method (ARM) allows a noninvasive calculation of the longitudinal cross-sectional area of the trachea (MTAv) and the airway resistance (Raw).ARM measurements were performed in 20 CF children and 20 controls during spontaneous breathing (SB), forced inspiration (FI), and forced expiration (FE).The mean MTAv value was comparable in the CF patients and the control subjects during SB, FI, and FE. The Raw was also comparable during SB and FI. However, the Raw during FE was higher in the CF patients than in the control subjects (7.9 ± 2.3 vs 5.0 ± 1.5 cmH2O l−1 s−1, respectively, p < 0.001). In the patients with CF, only the Raw during FE correlated with the predicted forced expiratory volume in 1 s (R2 = 0.37, p = 0.04).The tracheal cross-sectional area measured by the ARM is normal in children with CF but the increase in Raw during FE suggests an increase in intrathoracic airway distensibility.

► Tracheomalacia has been observed in patients with cystic fibrosis (CF).
► We used the acoustic reflection method to evaluate the trachea in children with CF.
► The cross-sectional area of the trachea in children with CF was similar to controls.
► But children with CF had an increase in airway resistance during expiration.
► Children with CF may have an increased intrathoracic airway distensibility.