The amount of fluid in the pleural cavity has varied from less than 100 to 1,500 c.c. The fluid has occasionally been seropurulent or yellow, thick and purulent, but in most instances the exudate is best described as fibrinopurulent. There is yellow or yellowish gray purulent fluid containing flakes of soft ragged fibrin.
The foregoing study has shown, on the one hand, that empyema is a frequent complication of streptococcus pneumonia and, on the other hand, that empyema following influenza with relatively few exceptions is caused by hemolytic streptococci. Empyema caused by this microorganism exhibits in some instances characters not seen with other varieties of pleural inflammation. The tissue between sternum and pericardium is often edematous and the adjacent fat has a firm brawny consistence. In some instances the exudate contains blood, and hemolysis has occurred so that the fluid has a diffuse red color. The occurrence of multiple pocketed collections of purulent fluid within the pleural cavity is peculiar to streptococcus empyema. These pockets have been found 6 times in association with abscess and 5 times with interstitial suppurative pneumonia. In the presence of an exudate within the pleural cavity, some part of the lung, usually the anterior surface behind the sternum and costal cartilages, is glued by fibrinous adhesions to the parietal pleura. Here occur pockets containing thin purulent fluid and softened fibrin or thicker creamy pus walled off by fibrin about the edges of the pocket. At the site of the lesion the lung, after it is separated from the chest wall, is marked by a shallow depression surrounded by the fibrin which has walled in the pocket. The little cavity thus formed, varying much in size, is usually oval, the long diameter being from 1 to 3 cm. These pleural pockets may occur over the external surface of the lung (Autopsies 452, 455, and 472) or between the internal surface and pericardium (Autopsy 452). Occasionally with partial fibrinous adhesion between the pleural surfaces there are both scattered pockets containing purulent fluid and a larger encapsulated collection of fluid; in Autopsy 455 the pleural surfaces were adherent and there was 100 c.c. of purulent fluid encapsulated in a space over the external surface of the lung, 12 × 8 cm. In Autopsy 452 the lower part of the pleural cavity was encapsulated and contained 650 c.c. of fluid. This tendency of empyema caused by S. hemolyticus to form encapsulated pockets is doubtless of considerable importance in the treatment of the condition.
Stone, Bliss and Phillips[[85]] have described these encapsulated pockets as “subcostosternal pus pockets” and have maintained that they are formed about the sternal lymphatic nodes. We have found them so widely scattered that this relation seems improbable.
Pneumococcus Empyema.—Empyema occurred in association with pneumonia referable to pneumococci 10 times, once with Pneumococcus II; 6 times with Pneumococcus atypical II; once with Pneumococcus III and twice with Pneumococcus IV. The lesion was seropurulent once; fibrinopurulent 8 times and purulent once. Fibrin in several instances was somewhat voluminous. In the following instance voluminous masses of fibrin had an important influence upon the attempted treatment.
Autopsy 473.—A. D. P., white, aged twenty-one, a student from Missouri, had been in military service two weeks. He was admitted to the hospital with influenza twenty-eight days before his death, and four days after admission there were signs of pneumonia. Paracentesis was performed on the right side on the eleventh day after admission; 4 c.c. of cloudy fluid which contained Pneumococcus III were obtained at this time and later in the day 800 c.c. were withdrawn. On the thirteenth day attempted withdrawal of fluid from both pleural cavities failed. On the eighteenth day aspiration of the right pleural cavity yielded only 30 c.c. of fluid. On the nineteenth day 400 c.c. of purulent fluid were withdrawn from the right pleural cavity. On the twenty-fifth day there was cyanosis and delirium. Shortly before death aspiration of the right pleural cavity was attempted, but only 4 c.c. of fluid were obtained.
Anatomic Diagnosis.—Chronic bronchopneumonia with lobular and peribronchiolar consolidation in left lung; fibrinopurulent pleurisy on both sides; purulent bronchitis and bronchiectasis.
On removal of the sternum, encysted purulent pleurisy is found between the inner surface of the right lung and the pericardium; there is here 450 c.c. of very thick creamy, greenish yellow pus entirely separated from the remainder of pleural cavity. The external part of the cavity contains 1,450 c.c. of fluid and voluminous masses of firm fibrin which placed in a measuring cylinder occupy 450 c.c. The left pleural cavity contains 400 c.c. of seropurulent fluid in which there is abundant sediment of fibrinous particles.
The right lung is compressed; the bronchi exude purulent fluid. The left lung is voluminous; in the upper and lower lobes there are small yellowish gray nodules of consolidation, grouped in clusters, and gray patches of lobular consolidation occur. Bronchi are dilated and filled with purulent fluid.
Bacteriologic examination shows the presence of Pneumococcus III obtained in pure culture from the blood of the heart and from the right pleural cavity. S. viridans is grown from the left lung; a plate from the right bronchus contained B. influenzæ, S. viridans and a few colonies of staphylococcus and M. catarrhalis.
The foregoing case is particularly noteworthy because aspiration failed repeatedly to yield more than a few cubic centimeters of fluid, doubtless because the voluminous masses of fibrin present in the cavity prevented escape of fluid. Aspiration was attempted shortly before death, but only 4 c. c. of fluid were obtained; nevertheless, at autopsy the right pleural cavity contained 2,350 c.c. of exudate. Another factor of much importance in relation to treatment is the encapsulation of 450 c.c. of purulent fluid between the inner surface of the right lung and the pericardium. It is possible that free drainage might have emptied the main cavity and perhaps even freed the encapsulated fluid.