The changes in calibre which occur in the trachea and large bronchi during respiration and coughing have been observed by bronchoscopy and measured by bronchography (Dekker and Groen, 1957;Holden and Ardran, 1957;Ross, Gramiak, and Rahn, 1955; Stutz, 1950a, b). The small airways of less than 3 mm. diameter appear to be responsible for about 90% of the resistance of the bronchial tree during normal respiration (Rohrer, 1915). The present study was undertaken to observe particularly the changes in the smaller airways, including the smaller bronchi and bronchioli, at varying lung volumes and during coughing. METHODSThe subjects investigated were patients who had had bronchograms for routine diagnostic purposes and in whom the region of lung investigated in this study was considered by bronchography to be within normal limits. Bronchograms were carried out by the injection of Dionosil Oily (Glaxo) through the cricothyroid membrane under local anaesthesia and without premedication. The bronchial diameters were measured from magnified films taken with a tube-tocouch distance of 43 cm. and a tube-to-film distance of 86 cm. The focal diameter of the anode was 0-3 mm. Exposures were made at 120 kVp, 20 mA. for 0-02 to 0-04 second, using fast films and screens.By this method bronchi which lie 10 cm. above the couch, i.e., about the centre of the lung in a normal person, are magnified 2-6 times on the film. Bronchi near the front of the chest, say 16 cm. from the couch, are magnified 3-2 times, and the posterior bronchi., say 4 cm. from the couch, are magnified 2.2 times. This magnification method has the advantage that the bronchi of less than 1 mm. diameter can be measured directly from the film. The method suffers from the disadvantage that movements of the bronchi during inspiration or expiration in an antero-posterior direction will give a change in magnification. The greatest change in antero-posterior position would be expected to occur in the bronchi close to the anterior chest wall and the least change in the posterior bronchi which move only a little relative to the 1 Present address: Torbay Hospital, Torquay, S. Devon. couch. During a maximal inspiration the sternum moves about 3 cm. anteriorly in an adult male with a vital capacity of 5 litres. This would increase the magnification of the most anterior bronchi from 3-2 to 3-6 times, a maximum increase of 12%. Most of the bronchi measured in these studies were lateral bronchi and the vital capacity of the patients was usually less than 3 1. so that the magnification error on full inspiration is probably much less than 5%. All measurements were corrected to give a mean magnification of 3.The procedure used in the investigations was as follows. After the routine films of the bronchogram had been taken the patient was encouraged to suppress coughing, and an oesophageal balloon attached to the end of a polyethylene tube was passed until the balloon lay in the lower third of the oesophagus. The patient lay supine on the couch and the oesophageal tube was attached to ...
S U M M A R Y Sixty-one cases of strangulation of the whole or a part of the scrotal contents have been reviewed. T h e patients underwent operation over a 15-year period at a children's hospital.Fifteen of the patients were in the first year of life.T h e aetiological basis of torsion of the spermatic cord and of the testicular vestigial appendages has been discussed.T h e importance of urgent scrotal exploration when the condition is suspected, of testicular conservation when possible, and of fixation of the opposite testis has been emphasized.Acknowledgements.-I a m indebted to Miss I. Forshall, M r . P. P. Rickham, and Mr. J. H. Johnston for kindly allowing me to review the cases treated by them. I a m particularly grateful to Mr. Johnston for his helpful criticism of the study.T h e drawings which illustrate this article were made by Mr.
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