The pleural and bronchial arteries anastomose partly with each other and partly with branches of the pulmonary artery.
With reference to the branches of the pulmonary artery going to the bronchi, it may be said that they, without giving special branches to the external layer of the bronchi, press on to the basal membrane and form a compact capillary network in common with the proportionately few branches of the bronchial artery.
Amidst differences of opinion, as between Küttner, Lalesque, and Cohnheim and Litten, there is a concurrence as to the chances of supplementary function by anastomoses between channels that are ordinarily separate. Küttner admits a modified form of terminal arrangement in the pulmonary artery, but at the same time claims an amount of potential connection that is liable to come into actual operation and suspend, if not destroy, the terminal type.
The correlation of both functional and nutrient vessels is so intimate that we believe there is no conclusive argument against the actual transfer of office from one to the other in certain strained conditions of disease; Virchow's experiment proves it.
The wonderful delicacy and distensibility of the enormous network of pulmonary vessels (relation of uncovered space in the alveoli to that covered by the vessels being 50 out of 200, Kuss); their capacity of response to great variations of supply and tension; the prompt supplementary function proven by Litten21 to belong to the tracheo-oesophageal, pericardial, phrenic, and pleuro-mediastinal arteries, and their equilibrium under the sensitive changes of the aortic system; the slower submission of the lesser circulation to the peripheral impressions, which markedly affect the aortic system; the facts verified by Lichtheim22 that on closure of any portion of the pulmonary artery the same quantity of blood will pass through the portion remaining open as before; that this is brought about through increase of pressure in the sections still open, and through the simultaneous increased rapidity of circulation and distension of the vessel walls; and that this mechanism is able to compensate for obstruction of three-fourths of the pulmonary artery,—are important factors in the anatomical and physiological relations of hæmoptysis.
21 "Ueber den Hämorrhagischen Infarct," Zeitschrift für klinische Medicin.
22 Die Störungen des Lungenkreislaufs, by L. Lichtheim, Berlin, 1876, p. 65.
ETIOLOGY.—The natural history of hæmoptysis is practically that of phthisis: exceptions to this will be noted hereafter. As heredity is largely a determining influence in the latter, it may be assumed that it qualifies its principal symptoms. More or less uniformity prevails in the transmission of normal or abnormal conditions, and we seem to find an illustration of the latter in the correspondence between the percentages of hereditary phthisis and those of hæmoptysis in such cases. Reginald Thompson23 says that "out of 1064 cases of well-marked inherited phthisis, 426 suffered from hæmoptysis." In his calculation he omitted all those in which the disease began with hæmoptysis. Had these then been included, they would have raised the percentage over that shown by the figures, which is slightly above 40. The rate would not then be much below that given as an average of cases of hereditary phthisis. This percentage of cases of hæmoptysis in hereditary phthisis is a sufficiently uniform transmission to prove the influence of heredity. Its influence is shown not only in the number of transmissions, but in the transmission of types; so that, as we have a family type of phthisis, we may have a family type of hæmoptysis, such as the cases where all the phthisical members of a family are subject to hæmoptysis of uniform characteristics, instances where the same uniformity in type is transmitted, and instances where the phthisical heredity appears to have its survival in moderate and transient attacks of hemorrhage.
23 The Causes and Results of Pulmonary Hemorrhage, p. 110.
Atavism is also seen in some family histories. We have in view such an instance, where the marked hæmoptysical tendencies of one generation skipped the next to reappear in the third.