Diagnostic significance of volume capnography in examination of patients with bronchial asthma
Aim: to study the diagnostic significance of volume capnography in examination of patients with severe and moderate bronchial asthma (BA). Materials and Methods. 171 patents were examined, of them 43 patients with severe BA and 45 patients with moderate BA. The control group included 83 relatively healthy volunteers. In all the participants, along with clinical examination, parameters of spirometry and volume capnography were determined using ultrasound computer spirograph SpiroScout (Ganshorn, Germany) equipped with a volume capnography function. Results. Volume capnography revealed the following changes in patients with BA in comparison with the control group: increase in the slope of phase III (indicates non-uniformity of ventilation and perfusion in the lung periphery due to pathology of the small airways) and increase in emphysema index (indicates hyperinflation of lung). The above indices had statistically significant differences in severe and moderate asthma. Based on the results of examination of healthy individuals, the normal values for the slope of phase III (<0.31 g/molL) and emphysema index (<43) were calculated. Diagnostic sensitivity and specificity of volume capnography were studied with subsequent construction of ROC-curves and calculation of AUC for the slope angle of phase III and for emphysema index. It was found that most informative in BA are parameters of specificity of the diagnostic test (slope of phase III - 90.32%, emphysema index - 96.77%). The subsequent construction of ROC-curves showed that the AUC value for slope of phase III and emphysema index was higher in severe BA compared to the moderate BA (0.74 and 0.86, respectively). Conclusion. The obtained data demonstrate the significance of volume capnography in the functional diagnosis of respiratory disorders in BA.