The Bradshaw lecture on the results of bronchial obstruction : delivered before the Royal College of Physicians of London on November 1st, 1910 / by G. Newton Pitt.

  • Pitt, G. Newton (George Newton), 1853-1929.
Date:
1910
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Credit: The Bradshaw lecture on the results of bronchial obstruction : delivered before the Royal College of Physicians of London on November 1st, 1910 / by G. Newton Pitt. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    Aneurysm of the Aorta. During the period taken, out of 11,000 post-mortem exami- nations there have been 140 aneurysms of the thoracic aorta. Thirty compressed the left bronchus, and 16 of these eroded into it; 5' compressed the right bronchus and none troded it. To contrast the results of compression produced by the various causes it may be noted that in this series, in 16 cases—that is, one-balf—there was bronchiectasis beyond the obstruction, but in only 8 was it associated with a marked fibroid thickening of the connective tissue and increased pigmentation of the lung with a thickened pleura. In several (6) there was also an acute terminal pneumonia, and in 4 an acute septic pneumonia ; in 3 there was an acute gangrene, aDd sometimes there was an acute pleurisy, but only once was there a pleuritic effusion. When there was no definite dilatation ol the tubes the lungs generally showed bronchi full of muco-purulent secretion, often with collapse and a more or less airless lung. The dilatation of the tubes takes place only in the part of the lung beyond the obstruction, and is irregularly dis- tributed, being generally least marked in the anterior part. The amount varies greatly ; in some cases the distension of the tubes is but slight, when the lung may be also collapsed or pneumonic. Marked increase in the fibrous tissue, as it occurs less frequently, appears to be to some extent a secondary change, and to be partly set up by the absorp- tion of the irritating contents. In advanced cases the fibrous trabeculae stand out, the lung is very tough, and may be riddled with intercommunicating cavities. In only one in twelve was an acute gangrenous condition noted, although in many the contents were very foul. The bronchiectasis requires at least two or three months in which to develop, but occasionally it took a year or more, and it is very remarkable how very latent the consti- tutional symptoms may be so long as the changes are limited to the fibroid lung beyond the obstruction. When much foul secretion is expectorated, the healthy part of the lung is apt to become infected, and if an acute septic pneumonia develop, the disturbance to health is intense. The ascending arch is not in very close relationship with the right bronchus, and only occasionally will an aneurysm of this part (usually a saccular one) compress the bronchus, and then on its anterior surface ; not infrequently it will also involve the trachea; in none of the cases did it rup- ture into the bronchus. Occasionally the azygos vein, which is in close relation to the right bronchus, may also be compressed, and this may be the explanation of the only case with pleuritic effusion. In none of the right- sided cases did the breath sounds entirely disappear, nor did a local bronchiectasis develop. A sac connected with the latter part of the transverse arch may compress more or less completely the left bronchus on its outer and anterior surface, and often the trachea as well, and very rarely the left pulmonary artery which lies above the bronchus (Fig 1). This arterial stenosis probably accelerates retrograde changes in the luDg and the development of the fibroid thickening, but it did not in any case lead to gangrene. In no case did an infarct form, and in only one did an aneurysm rupture into the pulmonary artery. When the aneurysm comes off lower down it will compress the bronchus from behind and on its outer side (Fig. 2). Sometimes, however, before the bronchus is completely occluded, the lung will become over-distended, there wiil he a hyper resonant note, and the distended lung may displace the heart and push down the diaphragm. That this condition may result has been almost entirely over- looked by authors, and no reference is made to it in the textbooks. Yet over-distension, we know, not infrequently results if the respiration is vigorous, when there is laryngeal obstruction in diphtheria, in tracheal obstruc- tion from an enlarged thyroid, thymus, or aneurysm, in asthma with spasm and therefore, with stenosis >>f the smaller bronchi, and in acute bronchitis and bronchiolitis. It is also what we might expect. With inspiration the chest expands and the surface of the lung closely attached to it by capillary action follows and the air is sucked past the obstruction as the lung attempts to open. With ex- piration there is a contraction of the lung, due to its elasticity, which is feeble, but sufficient for ordinary A 2 purposes. This drives the air from the smaller to the larger bronchi, because the pressure in the former is the greater. When forcible expiration is applied, the bronchi as well as the lung tissue are compressed with an equal pressure; if there is no obstruction ihe air passes on, and the pressure therefore falls in the larger bronchi. When an obstruction exists, however, this mechanism fails, the air has greater difficulty in escaping than it had in entering, and the lung becomes over-distended. The pressure may be so much raised that the diaphragm may be displaced two inches and the heart pushed out of position. This condition gradually develops and persists for a certain time, but by degrees the bronchi fill with secretion, thus increasing the difficulties of the ingress of air, and as the contained air is not replaced, and is subjected to high pressure, it becomes absorbed by the pulmonary blood, while the lung becomes solid, airless, and dull on per- cussion. Lichtheim has shown experimentally that when the bronchus is completely occluded this airless condition develops almost at once. In six of the cases the symptoms were so suggestive of pneumothorax that this diagnosis was more than once suggested. This possibility of over-distension as a result of bronchial obstruction has been so far overlooked by all authors that the only definite recognition of the condition I have noted, is by the late Dr. Pearson Irvine, who, in the Patho- logical Transactions for 1878, recorded a case of aneurysm pressing on a bronchus in which the lung was larger than normal, although fibroid and bronchiectasic; he came to the conclusion that the result of the pressure had been first to over distend the lung, that then the secretion had accumulated in the bronchi, and the air had been absorbed, while fibrosis and bionchiectasis from the greatly increased tension had compressed the blood vessels and impaired the nutrition of the tissues. C. Jacobsohn has aLo more than once noted that the position of the dullness set up by a growth at the root of the lung may vary with respiration owing to the over-distension of the affected lung, which is best shown by the x rays. Case X.—Saccular Thoracic Aneurysm Compressing the Left Bronchus and Producing an Over-distended Lung. By some it was thought that the case was one of pneumo- thorax. The patient was a man, aged 29 years, admitted in November, 1905. He had been in the army and had had syphilis. Cough had been present for a year, and had been worse for the last three months, with dyspnoea and pain in the left chest. He had no great distress while in bed; the left chest moved badly; there was no tactile vocal fremitus, and no voice nor breath sounds on the left side. On percussion the note was hyper-resonant. There was no cardiac dullness on the left, and on the right there was dullness, which varied with respiration, extending from the fourth rib out to beyond the right nipple and down to the liver. There was marked epigastric pulsation, the heart sounds were faint, and no bruit was audible. There was compensatory breathing over the right chest. There was considerable uncertainty with regard to the diagnosis, but it was thought that most probably the condition was due to an aneurysm pressing on the left bronchus. The patient was ex- amined with the x rays. The whole of the left side cf the chest was remarkably transparent compared with the right; no foreign body was visible; tbe heart was displaced nearly 2in. to the right of the sternum with deep inspiration, and back again behind the sternum with expiration. The diaphragm was depressed on the left side, but no trace of any aneurysm could be seen (Fig. 3). The temperature was normal and the pulse 72. There were no stridor, no evidence of any syphilitic ulceration of the trachea and bronchi, and no expectoration. It was elicited that three months previously a crust of bread had gone “ the wrong way,” but had this passed into the bronchus there would have been evidence before now of septic pneumonia. The extreme trans- lucency and distension of the left chest, with tbe absence of any change in the aorta, threw a doubt on the diagnosis of aneurysm, and it was thought that a possible explanation of such marked translucency might be a pneumothorax, although no bruit- d’airain could be elicited, and there was no evidence on the screen of a lung compressed by air. The left axilla was ex- plored with a Southey’s tube, but no air escaped. The result of this exploration was to produce an acute attack of pleurisy, and he felt very ill for some time. His temperature two days after- wards was 99° F., and on the next day 101.6°, with a pulse of 112 and intense pain. The temperature did not reach the normal again for nine days. In December the patient was tested with tuberculin with a negative result. Later his opsonic index to tubercle was 0.38. As the condition still remained obscure, the chest was again explored in December, with a negative result, except that there was again a sharp attack of pleurisy with pyrexia which lasted or ten days, when the condition again quieted down At