Hydatid disease of the lungs / by J. Davies Thomas.

  • Thomas, J. Davies (John Davies), 1844-1893.
Date:
1884
Catalogue details

Licence: Public Domain Mark

Credit: Hydatid disease of the lungs / by J. Davies Thomas. Source: Wellcome Collection.

Provider: This material has been provided by The University of Leeds Library. The original may be consulted at The University of Leeds Library.

    29/106 (page 21)
    That more or less loss of blood should accompany tho rupture of the cyst is only natural. If we consider the local conditions present the cause will be clear. When the wandering embryo settles itself in the lung a process of eneapsuling occurs, which results in the formation of a fibrous sac. With the advancing growth of the parasite, the capsule expands, the lung tissue is first compressed and ultimately destroyed, to an extent proportionate with the size of the hydatid. Meanwhile the bronchial tubes and blood- vessels likewise suffer from the pressure. Many of the smaller air-tubes are compressed, closed, and disappear, but usually some of the larger ones remain patent, and terminate by open mouths on the walls of the cavity. Whilst the integrity of the Echinococcus cyst is maintained, these openings are closed by the tense and closely applied wall of the parasite. As regards the blood-vessels, these too, when of small size, undergo degeneration and atrophy in consequence of the pressure, but some of the larger ones, although they become thickened and degenerated, yet remain patent, in consequence of the relatively great pressure of blood in their interior. Whilst the cyst is unruptured they are evenly supported by its elastic pressure, and thus their brittle walls are enabled to sustain the pressure of blood in their interior. The amount of pressure exerted by the fluid contents of the normal hydatid cyst is always considerable and sometimes very great. Its amount has not been estimated in a sufficiently large number of cases to permit an exact statement upon the point, but it is probable that the intrinsic intracystic pressure of a medium-sized hydatid is usually from 10 to 12 inches of water. But the pressure exerted by the cyst is actually much greater in many cases, for when it attains a large size it becomes subjected to the extrinsic pressure of neighbouring muscular agencies. For example, in the case of a large lung hydatid, we have to regard not only the intrinsic elastic tension of the cyst wall, but also the influence of the extrinsic pressure of the diaphragm ; of the opposite lung, heart, &c., acting through the mediastinum. The result is that the actual pressure of fluid inside the hydatid cyst may rise, as in one case measured by me, to 25 inches during inspiration, and 30 inches during expiration, and in this case, the coughing and violent expiratory efforts which occurred in the course of a few seconds caused an amount of tension in the cyst, sufficient to force the greater part of the fluid contents of the manometer to a distance of several feet beyond the instmment. The potential fluid pressure of a pulmonary hydatid has a very important bearing in many directions, some of which I shall allude to later on.