The effect of blows on the chest in producing hæmoptysis and phthisis has been the subject of medico-legal examinations in suits for damages. In all of such cases within our knowledge there has been the element of fright or great emotional excitement, and hence a complexity of causation. An hereditary tendency to phthisis was also present—a fact which diminished the force of the plea that the blow was alone responsible for the injuries to the health of the parties concerned.
Diseases or injuries of the brain may be mentioned as causes of pulmonary hemorrhage, which may occasionally be shown by hæmoptysis. Experimental pathology has recently thrown much light on these cases. (See [PULMONARY APOPLEXY], infra.)
It may be worth while, in view of recent researches, to refer to a form of hæmoptysis closely associated with a newly-discovered parasite, named Distoma Ringeri,45 after Ringer of Tamsui, Formosa, who discovered the parasite, but did not at once recognize its etiological relation to the endemic hæmoptysis. In a post-mortem of a man dead from rupture of an aortic aneurism he found the parasite lying on the lung-tissue, probably escaped from a bronchus. There were some small deposits of tubercle, no cavities, and slight congestion of the lungs. Manson found that these parasites were associated with a frequently-recurring hæmoptysis. Baely of Tokio46 discovered the parasite, probably before any others. It is quite common in North Formosa and through Japan. Manson says:47 "Endemic hæmoptysis can be readily diagnosed. There is a history of irregular, intermitting hæmoptysis, associated with a slight cough, and in the intervals of more active bleeding the expectoration once or several times a day of small pellets of viscid, brownish mucus. Examination of a small portion of the sputum with the microscope at once settles the diagnosis, sometimes as many as twenty parasites being found in a single field." Further examination is necessary to determine the manner in which this parasite produces the hæmoptysis.
45 The Filaria sanguinis hominis and certain New Forms of Parasitic Disease in India, China, and Warm Countries, p. 134, by Patrick Manson, Amoy, China.
46 London Lancet, Oct. 2, 1880.
47 Ibid., p. 143.
The association of bacilli tuberculosis with hæmoptysis is proven by a number of examinations. These will be referred to in their diagnostic relations at another page. It is not intended here to imply an etiological relation, because as yet our knowledge does not point to the blood-vessels as being the special or usual habitat of bacilli or the place of their most destructive efforts.
Hydatids of the lung are a cause of hæmoptysis which may come from congestion accompanying their growth, or from their rupture and consequent opening of blood-vessels.
Before proceeding farther we shall refer more fully than before to the conditions prepared by heredity, age and sex, etc. for the action of the exciting causes. The agencies were stated to be the peculiar vulnerability of the vascular and epithelial structures of the lungs. When the morbid imminence is reinforced by an infective element, as in phthisis, certain results follow which make easy the action of the incidental causes. Because of the enormous vascularity and great delicacy of structure of the lungs, and their liability to external influences, slight external irritants in such constitutions produce more than what follows in other cases. Instead of a transient hyperæmia or mild catarrhal inflammation, we may have that fluxionary hyperæmia of which an early outcome is hæmoptysis. Experimental pathology explains such occurrences by demonstrating that while a normal vessel, as in the mesentery, will require a pressure of seventy millimeters of mercury to produce extravasation of its contents, an inflamed one will not stand more than twenty-five millimeters. If catarrhal pneumonia proceed in its phthisical form, it adds its elements of danger.
After its early stage of congestion we have the initiative processes extending from the epithelial structures of the bronchi and alveoli to the alveolar wall, which becomes thickened. By means of the double pressure of abundant epithelial and fibrinous products retained within the alveolar cells, and of the increased growth in the alveolar walls, obliterative endarteritis and obstruction of blood-supply follow, the final result of which may be destructive changes opening the way for softening and ulceration, and consequent hemorrhage.