COMPLICATIONS AND SEQUELS.—The most important complications of influenza are inflammatory diseases of the lungs. The hyperæmia and intense bronchitis already described as occurring in the severer cases cannot properly be looked upon as complications. They constitute rather essential processes of particular forms of the disease. But capillary bronchitis, catarrhal pneumonia, and less frequently croupous pneumonia, arise as complications in the course of the disease. Satisfactory statistics are wanting, but Biermer estimates that from 5 to 10 per cent. of the whole number of patients suffer from inflammatory lung-complications, and holds that the bloodletting so frequently practised by the older physicians was due to a desire to combat inflammation. The comparative frequency of chest complications in different epidemics varies greatly, but the estimate of Biermer may be accepted as an approximate average.
Owing to the masking of the physical signs in the early stages and the pre-existing pulmonary oedema, it is not always easy to recognize at once the occurrence of capillary bronchitis. This complication is attended with increasing dyspnoea, decided lividity of the face and extremities, and great prostration. Crepitant and subcrepitant râles at the lower portions of the posterior dorsal regions, rapidly spreading to all parts of the chest, without dulness at first and with increased resonance later, instead of the signs of consolidation which are met with in pneumonia, are the signs which attend its appearance.
Catarrhal pneumonia occurs insidiously, with gradual intensification of the bronchitic symptoms about the fourth or fifth day, but it may set in as early as the second day, or much later, during convalescence. It is, as a rule, developed without chill or great increase in the fever.
Old persons and those of feeble constitutions are most liable to the foregoing complications.
Lobar pneumonia is less common. It is a late complication, occurring toward the close of the attack or even when the patient is beginning to get about. It is easily recognized, and differs in no wise from acute lobar pneumonia occurring under other circumstances.
In October, 1880, influenza being prevalent in Philadelphia, both epizoötic and epidemic, but very mild both among horses and men, I attended a medical student who, having had what he regarded as a cold for about a week, had kept at his work without treatment, until, upon the occurrence of a chill followed by grave thoracic symptoms, he was obliged to betake himself to bed. I first saw him the following day in the hospital of the Jefferson College. There were the symptoms of acute lobar pneumonia, with the signs of extensive consolidation of the left lung and pleurisy of the right side. Moreover, there were delirium and jaundice. The urine was non-albuminous. The next evening he died. At the same time many members of the class suffered from influenza, and a careful inquiry into the history of the case of this young gentleman satisfied me that the pneumonia had arisen as a complication in a neglected and moderate severe catarrhal fever. Until the eighth day before his death he was in excellent health. No examination of the body was permitted.
Graves21 thought that a kind of paralysis of the lungs, with great oedema, takes place in some cases, and attributed it to an affection of the vagus. It was his conviction "that the poison which produced influenza acted on the nervous system in general, and on the pulmonary nerves in particular, in such a way as to produce symptoms of bronchial irritation and dyspnoea, to which bronchial congestion and inflammation were often superadded."
21 Annals of Influenza.
It is certain that localized collapse of the lung often occurs. White and Guitéras attributed the consolidations of the lung to congestive collapse due to enlargement of the tracheal and bronchial glands and "disturbance of the great nervous tract about the root of the lung." They were enabled to satisfy themselves of the existence of glandular enlargement—adenopathie bronchique—in nine of their eighteen cases by percussion practised in the method of M. Geneau de Mussy,22 who was the first to call attention to the importance of percussing the spinous processes of the vertebræ over the course of the trachea. Following this line in the healthy subject, a distinct tubular (high-pitched and slightly tympanitic) sound is elicited by percussion down to the point of bifurcation of the trachea on the level of the fourth dorsal vertebra. Opposite the fifth and downward we get the lower-pitched pulmonary resonance. When the tracheal and bronchial glands are enlarged, the tubular sound over the upper dorsal vertebræ is replaced by dulness, which may contrast sharply, above with the tracheal, and below with the vesicular resonance.
22 Chirurgie médicale, Paris, 1874.