The preceding review should aid in the correlation of the clinical types of the disease with the respiratory lesions. All pulmonary lesions, from the least to the most localized, may be explained either by a subsidence of a less acute initial and diffuse involvement of the parenchyma, or by a less rapid and progressive spread of the necrotizing and inflammatory process from the upper respiratory tract through the bronchioles to the alveoli. This conception does not take into account the significance of the period of malaise, interpreted by the clinician as the period of invasion, but attempts to correlate the respiratory symptoms with the pulmonary lesions and their etiology.
Our own experience, like that of other observers (26, 104, 162), is that all fatal cases of this disease show pulmonary involvement in the form of pneumonia. The lesion varies greatly in intensity and in the amount of pulmonary tissue affected. In the descriptions which follow, the more diffuse and intense processes will be discussed first, and later those in which the inflammation localized and terminated in pseudolobar, lobar, lobular, or peribronchial pneumonia.
(1) ACUTE DIFFUSE FULMINATING TYPE OF PNEUMONIA
The majority of influenzal deaths have been examples of this acute type. Out of ninety-five cases, the total number studied, forty-four belong to this group in which the average duration of illness was nine days. They form the basis of the description which follows.
Gross Picture.
A striking feature of the external examination of the body is the intense rigor which involves all the muscles and is broken only with difficulty (78). This is associated with a rapid settling of the unclotted blood in the dependent parts which gives them an intense blue or bluish-purple color. The erythema of the skin which has been described clinically is not recognizable at the post-mortem table. There is, however, cyanosis of the face which reaches an intensity explained by the fact that this disease so often affects healthy, well nourished, muscular individuals. In a few instances the cyanosis is more extensive and gives a plum color to the entire body. All the mucous membranes share in the intense congestion and discoloration of the face. Slight jaundice is common, but marked variations in intensity occur. The external nares and the lips are almost invariably covered with blood-stained crusts. Even in the decubitus position, a thin, sanguinous fluid tends to escape in large quantities from the nose and mouth. The large veins of the neck are usually prominent, and the chest voluminous.
Distinct splanchnic engorgement is evident as soon as the peritoneal cavity is opened. The liver extends below the costal margin and is dark in color, but otherwise the abdominal cavity presents nothing characteristic of the disease. The diaphragm does not extend as high as usual, and the pleural cavity almost invariably contains an excess of fluid. Usually the quantity is small, but, on the other hand, it may be considerable, and in twenty-one of the forty-four cases the fluid exceeded one hundred cubic centimeters. The turgidity of the mediastinal tissues varies somewhat in degree (27). Generally the pericardial sac is smooth and glistening on both visceral and parietal surfaces; the pericardial fluid is not materially changed. Frequently (seventy per cent) there is dilatation of the right side of the heart (138, 141, 157), but aside from an occasional small endocardial or subepicardial hemorrhage (90, 108, 156), there are no lesions of consequence in the heart attributable to this disease[[5]] (162).
FIG. XIV. AUTOPSY NO. 96. LEFT LUNG. NOTE ITS SIZE AND THE PATCHY CONSOLIDATION.
