Pulmonary phthisis proves fatal by undermining more or less slowly the powers of life. The appetite and digestion fail. There is progressive loss of weight and of muscular strength. A greater or less degree of pyrexia is persistent, with diurnal exacerbations and night perspirations, forming what is known as hectic fever. Muco-purulent matter is expectorated in abundance, with fatiguing cough. The respirations are accelerated, and there is often suffering from dyspnoea. The pulse becomes more and more frequent and weak. Oedema of the lower limbs is of frequent occurrence. The patient dies by slow asthenia, the mental faculties usually remaining intact and the patient hopeful of recovery to the last.
The history of the disease in many cases embraces tuberculous affections elsewhere than in the lungs, and other complications. The duration is often shortened by some of these. The more important are tuberculosis of the intestines, tuberculous peritonitis, perforation of lung giving rise to pneumo-hydrothorax, pneumorrhagia, pulmonary gangrene, tuberculous meningitis, and chronic laryngitis affecting deglutition. The less important affections are pleurisy with effusion, thrombosis of the femoral or the iliac vein, a circumscribed non-tuberculous acute pneumonia, chronic laryngitis not affecting deglutition, intercostal neuralgia, and perineal fistula. Profuse hæmoptysis is sometimes a grave event, and may prove the immediate cause of death.
It is impossible to divide the course of pulmonary phthisis into sharply-defined stages based on anatomical changes. Often after death the lungs present in different situations all the changes which intervene between a fresh tuberculous product and cavities. The division into a stage of crudity of the product and a stage of softening is of no practical utility. There are no symptoms nor signs which are reliable for determining when softening has taken place. The existence of cavities can generally be determined by means of the cavernous physical signs, and the disease may be considered as advanced phthisis when cavities are discovered. The term incipient phthisis is used to designate an early period of the disease. Having passed the incipient or early period, and before reaching the advanced stage or stage of excavation, cases may be conveniently grouped according to the amount of the tuberculous affection. In different cases and at different periods in the same case the affection is either small, moderate, considerable, or large. Exact chronological divisions are impracticable.
ETIOLOGY.—Pulmonary phthisis, as a rule, is developed irrespective of any antecedent affection of the lungs. The researches of Louis established the fact that the phthisical affection is very rarely preceded by bronchitis, either acute or chronic.3 My clinical studies have led to the same result.4 That a neglected cold may eventuate in phthisis is a traditional popular error, unfortunately held also by some medical writers and practitioners. The error is to be regretted because it often interferes with hygienic management in cases of phthisis. The name chronic catarrhal phthisis proposed by Niemeyer was based upon this etiological error. It is a matter of common clinical observation that persistent bronchial inflammation leading to pulmonary emphysema, and often accompanied by asthma, involves no liability to phthisis. The long-continued inhalation of coal- and stone-dust, of the oxide of iron, and particles of other substances gives rise to bronchitis and interstitial pneumonia (pneumonokoniosis, anthracosis, siderosis, etc.), but is rarely followed by the common form of pulmonary phthisis. It is common for phthisical patients to suppose, as a matter of course, that their disease originated in a cold. In giving the previous history they often say that they took cold at a certain time. The analysis of carefully-recorded cases shows that very rarely does the disease follow directly upon an attack of bronchitis, notwithstanding that the frequency of the latter, from the law of chances, would involve an accidental concurrence in a certain proportion of cases. Acute lobar pneumonia or pneumonic fever has little or no tendency to eventuate in phthisis. This statement is sustained by the researches of Louis and by my clinical studies. In the rare instances in which phthisis follows either acute pneumonia or bronchitis, the latter diseases act only as auxiliary causes of the phthisical affection if the sequence be more than an accidental connection. This statement applies also to pleurisy with effusion. In certain of the few instances of phthisis apparently having been preceded by pleurisy it is probable that the former was the antecedent disease, occurring early in the history of the phthisical affection and retarding or arresting the progress of the latter. It may be added that there is no ground for supposing that phthisis is ever produced solely by traumatic causes acting upon the chest.
3 Recherches sur la Phthisie, 1825.
4 Phthisis, in a Series of Clinical Studies.
It is an old doctrine that bronchial hemorrhage may be causative of phthisis. This doctrine has been recently revived by Niemeyer and some others. It is disproved by the following clinical facts: in two-thirds of the cases in which hæmoptysis antedates phthisis the development of the latter is after the lapse of a considerable period—weeks, months, or years. The instances are few in which phthisis immediately follows the hemorrhage. The occurrence of hæmoptysis during the course of phthisis, as a rule, is not followed by any increase of the phthisical affection. On the contrary, the local symptoms are not infrequently relieved by the hemorrhage. It is, however, to be remarked that hæmoptysis as a forerunner of phthisis is of much significance. In the larger proportion of cases phthisis follows its occurrence sooner or later. It is to be added, in view of the recent discovery by Koch, that bronchial hemorrhage may proceed from the same local cause which afterward leads to the development of phthisis—namely, the presence of a special micro-organism.
The etiology of pulmonary phthisis not involving any antecedent affections of the lungs nor any appreciable local causes, it would seem to follow that the disease involves either a predisposing or a causative agency elsewhere within the organism; and as, with our present knowledge, the source of this intrinsic agency cannot be localized, it is customary to say that the disease has a constitutional origin. This use of the term constitutional here, as in other instances, expresses an important fact—namely, that the disease is not purely local; that is, attributable solely to extrinsic or any appreciable causes acting on the affected part. At the same time, the term is a confession of the imperfection of our knowledge, inasmuch as it does not specify the nature of the causative or predisposing agency, nor its origin, beyond the statement that it is not local. That the constitutional agency has a special character is a logical inference from the fact that the disease may be said to have such a character. The term vulnerability does not fully express the special character of the constitutional agency. The condition of the constitution which stands in a causative relation to the disease is something more than an undue susceptibility to morbific influences of any kind—a susceptibility giving rise to diseases the nature and seat of which are accidental. The condition is one which has relation both to the character and the situation of the pulmonary affection. Such a condition is expressed by the term cachexia.
It remains to inquire whence arises this phthisical or tuberculous cachexia.
A congenital predisposition or diathesis exists in a certain proportion of cases. This is to be inferred from the number of instances in which several or many members of a household, brothers and sisters, become affected with phthisis. There may or may not be evidence that this predisposition is inherited. An inherited predisposition is to be inferred from the number of the cases in which parents or grandparents were phthisical. While statistical facts show undoubtedly heredity as involving a causative agency, making due allowance for the law of chances, it is important for the physician to bear in mind that a tuberculous parentage involves only a certain measure of liability to phthisis in the offspring. The progenitors of many healthy men and women have been phthisical. There are instances of large families of children in which many have died with phthisis, leaving, however, some who escape this disease and are in all respects healthy.5 The question arises whether in cases of phthisis where there is lack of evidence of a congenital predisposition the diathesis may not be innate. The affirmative answer seems probable in view of the inability oftentimes to find any rational explanation on the supposition that the diathesis has been acquired. Positive data bearing on this question are of course not available.