Changes in lung inflation in asthma in patients with osmotic airway hyperresponsiveness

Abstract

The scientific literature does not provide enough information on whether bronchial hyperresponsiveness to hypoosmotic stimulus in patients with asthma can lead to more pronounced disturbances of regional lung ventilation.Aim. to characterize lung inflation in asthma patients with osmotic airway hyperresponsiveness.Methods. The lung inflation was studied by body plethysmography, as well as by three-dimensional volumetry, planimetry, and multispiral CT densitometry in 24 patients (group 1) with persistent mild asthma and osmotic airway hyperresponsiveness, identified by the bronchoprovocation test with inhalation of distilled water (IDW) (the average ДРБУ1 was —21.1 ± 3.2%). The comparison group (group 2) consisted of 49 patients with no response to IDW (the average ДББУ1 was —3.7 ± 0.5%; p = 0.00001).Results. Group 1 had lower lung function (FEVj was 83.6 ± 4.5%; FEF50 was 58.1 ± 5.8%) at baseline in comparison with the group 2 (96.7 ± 2.2%, p = 0.0042 and 75.5 ± 2.2%, p = 0.016, respectively) and higher indices of lung inflation at body plethysmography (RV was 153.2 ± 12.5 and 127.5 ± 4.0%, respectively; p = 0,027; RV/TLC was 128.8 ± 5.5 and 109.9 ± 2.8%, respectively; p = 0.015). According to three-dimensional volumetry, the indicators of expiratory lung inflation (526.0 ± 117.8 vox) and average residual inflation of both lungs (13.1 ± 2.6 vox) in group 1 were significantly higher than in group 2 (301.5 ± 55.8 vox, р < 0.05 and 9.1 ± 1.6 vox,р < 0,05, respectively). The patients with osmotic airway hyperresponsiveness also showed higher values of the expiratory area in the middle zone (235.3 ± 29.4 and 149.2 ± 14.9 pix, respectively; p = 0.00 47) and the lower zone (292.3 ± 37.9 and 178.6 ± 18.6 pix, respectively; p = 0.0034) of the lungs.Conclusion. Asthma patients with osmotic airway hyperresponsiveness have lung hyperinflation with impaired lung ventilation predominantly in the middle and lower zones.