By experience and observation much is learned from the character of the breathing, of the cough, and of the expectoration ; and, as aids to diagnosis, they must not be omitted ; but the student must be very careful not to draw " conclunions from any of these symptom alone. The prolonged wheezing sound, in the act of expiration, by a person laboring under emphysema, is very characteristic in extreme cases; the cough is deficient in expiratory power; it seems a soft, forceless effort, with very little vocal sound, and the voice cannot be elevated without difficulty and fatigue ; other conditions, how ever. give rise to characters very similar, such as pressure on the trachea or large bronchi, and even chronic dilatation of the smaller tubes, when obstructed by thick, purulent secretion.
The cough of hooping-cough is itself diagnostic, but must not be confounded with the crowing inspiration of childhood, nor with the harsh raucous sound of croup or laryngitis ; by parents it is sometimes alleged to exist when the child is merely suffering from the violent paroxysmal cough which sometimes attends extensive tubercular deposit, and is not unfrequently a precursor of hydrocephalus. The loss of voice in affections of the larynx, and the noisy breathing which is audible at a considerable distance, when the disease is accompanied by partial closure of the glottis, are almost unmistakable.
The ringing cough of croup, once heard, can scarcely be forgotten ; but false diagnosis has not unfrequently been made, from some sound which has merely simulated it, being alone taken into consideration. The short hacking of early phthisis, and the stifled and suppressed cough of its more advanced stages--the rattling and straining, often ending in sickness, attending the emptying of a large cavity—are all more or less significant.
The absolute quickness or slowness of respiration, and also its ratio to the rapidity of the pulse, are rather to be regarded as evidence of the severity of the affection than as specially pointing out its nature ; such, for example, are the very hurried breathing of extensive tuberculosis, and the want of corre spondence between its increased frequency and the acceleration of the pulse in severe pneumonia. A distinction is to be made between the evidence of quick breathing derived from observation and the sensation of the patient that it is short. The character of the sputa often helps to correct our diagnosis when there is anything like incongruity in the symptoms or physical signs of disease. The chief conditions which may be observed are these : simple mucus,
of varying degrees of adhesiveness and amount, in pleurisy, catarrh, bron chial irritation, and bronchorrhcea; mucilaginous or rice-water sputa, seen in the early stages of phthisis ; purulent mucus in chronic bronchitis ; unmixed pus coming from a cavity ; adhesive rust-colored mucus, very distinctive of pneumonia; admixture of blood, from slender streaks to copious hemorrhage; and offensive discharges. In many instances these varieties approximate very closely to each other ; thus the muco-purulent expectoration of bronchitis may assume the appearance of unmixed pus. When bronchitis coexists, as it so often does, with phthisis, the sputa present every degree of consistency, and the imperfect admixture of the secretions due to each cause sometimes points out their combination. In the earliest stage of phthisis it is only that of bronchial irritation, and in pleurisy there is usually no expectoration be yond a little salivary-looking fluid glairiness or adhesiveness. and especially a brown tinge, prove that the inflammation is not confined to the pleura. Puriform sputa may have most of the characters of a cavity when the pus comes not from a vomica, but from the cavity of the pleura; in such circum stances, a gush of pus, instantaneously discharged, would indicate that the opening into the pleura was a consequence of empyema, and not of phthisis. With reference to the rusty sputa of pneumonia, while the adhesiveness is generally in proportion to the severity of the inflammation, the student must be careful to ascertain correctly, in cases where the secretion is more abundant, that the color is really produced by slight admixture of blood, and is not caused by the coloring matter of wine or medicine.
The blood expectorated in phthisis differs from that of pneumonia. not only in its brighter color, but in its being less perfectly intermixed with the other secretion; its amount is exceedingly indeterminate. In a large proportion of consumptive patients it may be ascertained that hemorrhage from the smallest to the largest amount has at one time or other existed, and therefore the fact in any individual case is not without value; but it is true that certain phthisical patients escape altogether, that in some cases it is dependent on other causes, and that patients often sedulously endeavor to conceal or ig nore it.