LUNG-FUNCTION, CT-SCAN AND X-RAY IN UPPER AIRWAY-OBSTRUCTION DUE TO THYROID GOITER

The purpose of this study was to assess the clinical reliability and t o compare routine lung function tests (maximal flows and resistance) a nd radiological images (computed tomography (CT)-scan and X-ray) in up per airway obstruction. We, therefore, performed these examinations pr ospectively 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 re sistance. CT-scans and X-rays were performed during apnoea at function al 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 correl ated with each other. On CT-scan the tracheal cross-sectional area at the zone of tracheal narrowing could be evaluated in 26 patients and w as 58+/-17% (CT1/2) of the control area 2 cm above the carina (CT2). O n X-ray the sagittal and coronal tracheal diameters at the zone of nar rowing could only be measured ha 16 subjects and were 60+/-17% (X-dia( 1/2)) of the diameter at the control level. CT1/2 and X-dia(1/2) were significantly correlated to each other. No correlation was found betwe en the lung function tests and the radiological indices except airway resistance and CT2. Routine lung function and CT-scan do not provide c omparable information on the degree of airway obstruction due to a goi tre. Furthermore, X-ray of the trachea seems to be unreliable in visua lizing upper airway obstruction.