Lung function, CT-scan and X-ray in upper airway obstruction due to thyroid goitre

Abstract

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.