Wedal's63 results confirm this view of the harmlessness of punctures during the febrile stage; and, more than this, they show that they hasten the cure. He operated on 17 patients from the second to the fifth day, and three times from the eighth to the tenth day. In cases of acute disease, where the patients were exempt from pulmonary or bronchial complications, the cure was not protracted beyond the twelfth day. Some were cured by the sixth day. His patients were, for the most part, vigorous men, young soldiers—very favorable subjects. Ordinarily, however, as shown by J. L. Mason's64 report of 132 cases where the operation was not performed, the duration of the attacks was weeks, and in some cases months. He considers the operation more apt to be successful if performed early in the disease, and that the existence of fever is no contraindication. The author has always pursued a more conservative course, and abstained from operating in the febrile stage unless, as in three instances, the effusion was so rapid in its formation that there was danger of serious consequences from the amount of the fluid. In these three instances the result was successful and without unpleasant sequelæ. Moutard-Martin65 states that aspiration made during the febrile stage is in no way prejudicial to the patient. Dieulafoy66 advises us to wait until the fever falls.
63 Étude clin. des épanchments pleurit., 1877.
64 Boston City Hospital Reports, 3d Series, 1882.
65 Loc. cit.
66 De la Thoracéntèse dans la Pleur. Aigue, 1878.
To remove the effusion during the inflammatory stage does not appear to be rational treatment unless the quantity is so excessive as to endanger the life of the patient. The fluid remains limpid unless exposed to air or contact with foreign substance. When, after a time, there is some coagulation, it is only of a thin layer which covers and protects the roughened surface of the pleura. A certain amount of effusion is useful; it separates and bathes in a bland fluid the tender and inflamed surfaces, and keeps at rest the affected portion of the lung. The lung in health exercises a constant traction upon the pleural sac, the vessels of which have therefore to sustain a negative or aspiratory pressure: this being so, it is physiological that if these vessels become temporarily weakened and congested by the inflammatory process, increased exudation proceeds from them. The effect of this exudation is to neutralize lung-traction, and therefore to lessen the afflux of blood to the weakened vessels. "Fluid effusion being thus both natural and salutary, in acute pleurisy we must be watchful, but not meddlesome" (Powell). We must not hurry, but we must try if nature will not by spontaneous absorption cause it to subside. We can ordinarily do this up to the end of two or even three weeks before resorting to artificial means.
The defervescence in pleurisy, we have seen, has no fixed period, as in pneumonia. In favorable acute cases the absorption begins as soon as the temperature begins to fall. Moreover, the liquid may be absorbed, notwithstanding the continuance of fever, and the effusion may continue notwithstanding the defervescence. In the subacute form the febrile period passes by unnoticed, although the effusion is often in large quantity.
When not urgent, how long should we wait for absorption of fluid? This is a question much discussed, and not yet settled. What becomes of the effusion in the acute pleurisies?
In the first days of its formation the liquid portions of the effusion are reabsorbed by the normal vessels of the serous membranes at the points left intact and the recent vessels of the neo-membranes, but the organization of these last demands, to be complete, from two to three weeks; it is not until the end of that time that they will be most favorable to reabsorption. Dybkowsky points to the anatomical fact that the lymph-vessels are found only in those parts of the costal pleura which cover the intercostal muscles, while the portions which are reflected over the ribs are destitute of such vessels.
On the other hand, the eccentric pressure made by a considerable effusion on the pleuræ may retard their vascularization and lengthen out the work of absorption. Moreover, during the time necessary for that organization a certain quantity of coagulable fibrin is deposited on the surface of the serous membranes. The pseudo-membranous bridles are not slow in forming, and cause the adhesions which press the lung against the costal wall, the vertebral gutter, and the superior parts of the thoracic cage, toward which the effusion tends to force them.