The purpose of this study was to assess the clinical reliability and to compare routine lung function tests (maximal flows and resistance) and radiological images (computed tomography (CT)-scan and X-ray) in upper airway obstruction. We, therefore, performed these examinations prospectively in 28 female patients (aged 68±13 yrs) with a goitre and without pulmonary disorders. Lung function measurements consisted of maximum expiratory and inspiratory flow-volume curves and of airway resistance. CT-scans and X-rays were performed during apnoea at functional residual capacity FRC). Peak expiratory flow was 3.6±1.3 l·s-1 (i.e. 62±21% predicted); airway resistance was 0.38±0.14 kPa i.e.149±58% pred); and specific conductance was 1.0±0.3 kPa (i.e. 70±24% pred). Almost all lung function tests were significantly correlated with each other. On CT-scan the tracheal cross-sectional area at the zone of tracheal narrowing could be evaluated in 26 patients and was 58±17% (CT( 1/2 )) of the control area 2 cm above the carina (CT2). On X-ray the sagittal and coronal tracheal diameters at the zone of narrowing could only be measured in 16 subjects and were 60±17% (X-dia( 1/2 )) of the diameter at the control level. CT( 1/2 ) and X-dia( 1/2 ) were significantly correlated to each other. No correlation was found between the lung function tests and the radiological indices except airway resistance and CT2. Routine lung function and CT-scan do not provide comparable information on the degree of airway obstruction due to a goitre. Furthermore, X-ray of the trachea seems to be unreliable in visualizing upper airway obstruction.
Melissant, C. F., Smith, S. J., Perlberger, R., Verschakelen, J., Lammers, J. W. J., & Demedts, M. (1994). Lung function, CT-scan and X-ray in upper airway obstruction due to thyroid goitre. European Respiratory Journal, 7(10), 1782–1787. https://doi.org/10.1183/09031936.94.07101782