Malcolm Green

Fall in vital capacity with posture.

In a study of 147 subjects (50 normals, 50 with obstructive, and 47 with restrictive lung function), the mean reduction in forced vital capacity from standing to supine (delta FVC) was 7.5% (SD +/- 5.7), 11.2% (+/- 13.4), and 8.2% (+/- 7.7) respectively, with no significant difference between groups. The respective 95% upper confidence limits were 19%, 38% and 24%. We conclude that delta FVC greater than 25% associated with normal or restrictive lung function or greater than 35% associated with airways obstruction should be an indication for further study of diaphragm function.

Transbronchial aspiration of subcarinal lymph nodes

Transbronchial needle aspiration of subcarinal lymph nodes has been undertaken in 60 consecutive patients with pulmonary malignancies undergoing routine fibreoptic bronchoscopy. Four aspirates from the subcarinal nodes contained malignant cells; three squamous cell carcinoma and one adenocarcinoma. Four of 40 (10%) of patients with non-small-cell carcinoma of the lung had a positive aspirate. We have not confirmed the high positive rate previously reported, but nevertheless transbronchial needle aspiration provided useful staging information in some patients. The technique is rapid, safe and simple, and can easily be applied in a routine bronchoscopy service for all patients with suspected cancer, or selected patients under active consideration for surgery.

Response of the lung airway to exercise testing in asthma and rhinitis

The reactivity of the large and small airways of the lung in a group of ten atopic subjects with rhinitis was compared with that in ten non-atopic control subjects and in 17 with atopic asthma. Atopic state was assessed by skin prick testing with 22 common allergens and by measurement of total serum immunoglobulin E (IgE) antibody. The atopic state of the rhinitis and asthma patients was similar. Exercise provocation tests were performed on each subject and changes in airway function were measured by peak expiratory flow rate, forced expiratory volume in one second, vital capacity, maximal expiratory flow volume curves and closing volume. There were no statistically significant differences between the changes in lung function after exercise in the rhinitis patients compared with the controls. There were, however, statistically significant changes in all the measurements of respiratory function in those with asthma compared with the other two groups. The falls in forced expiratory flow rates in the asthmatic subjects were greater at lower lung volumes than near the total lung capacity, perhaps indicating that narrowing of small, as well as large, airways was occurring. No correlation was found between the magnitude of the airway response to exercise and either the total serum IgE antibody or the mean weal diameter of positive skin tests in each subject. Atopic subjects with rhinitis but not asthma showed no evidence of bronchial hyper-reactivity on exercise testing. It is therefore suggested that single exercise provocation test can discriminate subjects with atopic asthma from those with other atopic disorders.

AN EVALUATION OF THE TUBERCULOSIS AGGLUTINATION TEST

The tuberculosis agglutination titre as described by Nicholls (1975) was measured without prior knowledge of the diagnosis in 27 patients with open pulmonary tuberculosis, 100 patients with other diseases and 14 control patients with no apparent disease. Reproducibility of the test, as judged by repeat estimations on split samples, was poor. When attempting to distinguish between the disease categories the test gave 29% false negatives in patients with tuberculosis and 52% false positives in patients with other disease. Therefore the tuberculosis agglutination titre cannot be recommended for use in distinguishing tuberculosis from other conditions.