16 The different abnormal modifications of sounds produced by the whispered voice were first named and described by the author. Vide Manual of Auscultation and Percussion.
The normal points of disparity at the summit of the chest render the diagnosis of incipient phthisis by means of alterations in the resonance on percussion, the respiratory sounds, the vocal resonance, and the whispered voice a problem in some cases of not a little difficulty. In these cases an examination of the sputa for the presence of the tuberculous parasite may furnish proof of the existence of the disease. This proof may in some instances be obtained when the physical signs, together with the symptoms, do not render the diagnosis positive, and it may be sought for in order to corroborate the evidence derived from other sources. The author can testify from considerable experience to the value of an examination of sputa for bacilli in cases in which the diagnosis is not rendered positive by other signs and by symptoms. It must, however, be borne in mind that the absence of bacilli in the sputa is not sufficient to exclude phthisis, especially if but a single examination be made. In doubtful cases, if an examination of the sputa be negative, the examination should be repeated. The weight of evidence against the existence of phthisis is, of course, greater in proportion to the number of examinations with negative results.17
17 The following method of staining the bacilli tuberculosis in the sputum is essentially that recommended by Ehrlich in the Deutsche medicinische Wochenschrift, Mai 6, 1882:
It is important that the sputum to be examined should be derived from the lungs, and should not be solely that from the upper air-passages. A small opaque particle from the sputum is to be pressed between two cover-glasses, so that when these are drawn apart a thin film will remain upon each. Each cover-glass, as soon as the film is dry, is to be passed, with the preparation upward, rather rapidly three times through the flame of a Bunsen's burner or of an alcohol lamp. The preparation is now ready for staining.
A small quantity of water in a test-tube or flask is now shaken with an excess of aniline oil (which need be only in small amount), and after a few moments is filtered through moistened filter-paper. To the clear filtrate thus obtained is to be added, drop by drop, a saturated alcoholic solution of fuchsin (gentian-violet, methyl-violet, and several other aniline colors may be substituted) until the fluid begins to be opalescent, showing that it is saturated with the coloring agent. In this manner an alkaline-aniline staining solution is prepared.
Into this staining solution the cover-glasses, having the dried films of sputum prepared as above described, are dropped, preferably so that they will float with the preparation downward. Here they remain from a half hour to twenty-four hours. If taken out in a short time, the fluid, at least for a time during the staining process, should be heated moderately over a water-bath, and in any case the process of staining is accelerated and rendered more certain by heating.
After removal from the staining fluid the cover-glass is washed for a few moments in water, and is then dipped into a mixture of one part of pure nitric acid (it should contain no nitrous acid) to about three or four parts of water. Here it remains only a few moments, when it will be found that the preparation has lost its color, although a part will be restored by the subsequent washing in water, which should be done at once. If the preparation has not been sufficiently decolorized, it may be placed again in nitric acid, but it is not necessary or desirable that it should remain there many minutes. The object of the nitric acid is to extract the color from all but the tubercle bacilli.
The preparation may now be at once examined either in glycerin or (after drying or after treatment with alcohol and oil of cloves) in balsam. Ehrlich recommends, previous to this, a staining of the background with some color other than that of the bacilli; thus, with methyline blue if the organisms are stained red with fuchsin. This staining of the background, however, is not necessary. While the ideal method of studying the stained bacilli is by means of Leis's oil-immersion lenses and Abbé's illuminating apparatus, they can usually be seen readily enough with the high powers in ordinary use, such as the one-fifth or one-sixth inch objectives of our American microscope. After staining with fuchsin the bacilli appear as short rods of a red color, frequently curved or bent.
The adventitious sounds which have been mentioned—namely, the subcrepitant râle and the pleural friction murmur—sometimes afford valuable aid in the diagnosis. Taken in connection with the direct signs obtained by auscultation and percussion, these accessory signs when present make the diagnosis positive: they are by no means uniformly present, and therefore their absence is not proof against the existence of a phthisical affection. To these accessory signs another sign may be added—namely, an abnormal transmission of the heart-sounds within one of the infra-clavicular regions. In the middle of this region there is nearly an equal transmission of these sounds normally. Comparing the two sides as regards the two sounds respectively, the first sound is a little louder on the left, and the second sound a little louder on the right side. Now, with a little solidification the sounds may be better transmitted, so that they are abnormally loud on the affected side.
A decision that there is no physical proof of phthisis must rest on the absence of all the foregoing signs after repeated examinations of the chest.