The impact of adenoid hypertrophy on pulmonary functions measured using impulse oscillometry in preschool-age...

To assess pulmonary impedance [resistance (zR5, zR20, R5-20, Fres, and AX) and reactance (zX5 and zX20)] using impulse oscillometry (IOS) in children with adenoid hypertrophy (AH) and its association with the degree of AH, and to evaluate subsequent changes in pulmonary function 3 months after adenoidectomy.

This prospective cross-sectional study was conducted with 170 preschool-age children [110 with AH and 60 sex- and age-matched healthy controls (HCs)]. Pulmonary function was analyzed using IOS at baseline (1st visit) in all participants and 3 months after adenoidectomy (2nd visit) in patients who underwent the operation.

The IOS parameters of zR5, zR20, R5-20, Fres, and AX were higher, but zX20 was lower, in children with AH compared to the HCs (p < 0.05 for all). The parameters of zR5, Fres, and AX were higher in children with grade IV AH than in those with grade I (p < 0.001). zR5, zR20, R5-20, Fres, and AX decreased, but zX20 increased, after adenoidectomy (2nd visit) compared to baseline (1st visit) (p < 0.05). Post-adenoidectomy (2nd visit) zR5, AX, Fres values were higher in children with AH compared to baseline values in the HCs (1st visit) (p < 0.05). The area under the ROC curve (AUC) value for estimating adenoidectomy was 0.741 for zX20 (CI 0.648-0.834, p < 0.001) with a cut-off value of  ≤ -3.21, sensitivity of 68.8%, and specificity of 70%.

This study shows that IOS is a useful method for demonstrating subclinical bronchial obstruction in preschool-age children with AH with greater pulmonary impedance (resistance and reactance). Pulmonary impedance decreased 3 months after adenoidectomy, but remained higher than in the HCs. The IOS parameter of X20 may be predictive of adenoidectomy. This study evaluated the pulmonary functions of children with adenoid hypertrophy (AH) using impulse oscillometry (IOS) and the association with the scale of AH. Pulmonary functions were analyzed using IOS. The main IOS parameters include resistances (zR5 and zR20), reactance (zX5 and zX20), R5-20 (resistance at 5 Hz minus resistance at 20 Hz), resonant frequency (Fres), and AX. Fres is the point at which reactance is zero and is measured in Hz (1/s). The Reactance Area (AX - "Goldman Triangle") represents the integrated low-frequency respiratory reactance magnitude between 5 Hz and Fres. Faster frequencies of R (~ 20 Hz) reflect larger airways, regarded as resistance around the central airways. Lower frequencies of R (~ 5 Hz) providing information around the entire (small and large) airways. Peripheral (small) airway resistance is defined by R5-20. IOS parameters of zR5, zX20, Fres, and AX differed among AH grades I-IV and compared to the HCs (p < 0.001 for all).