3. Sero-fibrino-purulent pleurisy. Empyema. This is usually very dangerous as well as complicated. It may supervene on the last described form. It may depend on rupture into the pleura of abscess of the lung, bronchial glands, liver, diaphragm or intercostal space and the infection of the chest cavity. It may in the same way follow the laceration of a bronchium by a broken rib, the perforation of the intercostal space by a foreign body, or (in cattle) the penetration of the chest by a sharp pointed body from the reticulum. It may follow at once on pleurisy of a very high grade. Probably in all such cases there is infection of the pleura by pus microbes. When there is a communication with a bronchium, the reticulum or the external air there are usually septic germs in addition, and the contents of the chest become fœtid.
The purulent fluid may accumulate in the lower part of the pleural sac, or it may be confined in abscess form in the false membrane, and extend thence into surrounding tissues. The pus-containing pleura, or cavity infected by the pus germs, assumes the appearance of a granulating surface, or of the lining membrane of an abscess, and continues to produce pus in greater or less amount.
The formation of pus in the pleura is known as empyema. When air enters the pleura through a wound perforating the chest wall, or when gas is formed in the pleura, the condition is pneumothorax. As liquid is usually present as well it is hydro-pneumothorax.
Tubercular and other forms of pleurisy have in certain cases been superadded to the specific local lesions, by which such diseases are individually characterized.
Prognosis. Occurring in an otherwise healthy system and especially if confined to one side of the chest, pleurisy is not frequently fatal, and under appropriate treatment recovery is oftentimes rapid and satisfactory. A certain number of cases merge into chronic hydrothorax, the inflammation apparently subsiding, but reabsorption failing to take place. The hydrothorax may last for months or even a year.
Treatment. If seen during the chill and before inflammation has been definitely established every effort must be directed to secure its abortion, if possible. No time should be lost in placing the patient in a warm comfortable stall or box, covering him with woolen blankets and actively rubbing and loosely flannel bandaging the legs. Warm drinks and warm injections must be given. Half an ounce or an ounce of camomile or boneset in infusion in two or three quarts of hot water, or in the absence of this any of the carminatives, or etherial, alcoholic or ammoniacal stimulants may be given. Pilocarpin in 7 grain dose hypodermically may promptly secure a revulsion of blood to the skin and at once overcome the chill and prove a most effective derivative from the pleura. Placing the legs in buckets of hot water, or the whole animal in a hot air bath will often act equally well. Packing the chest and even the abdomen in a blanket wrung out of very hot water and covering it closely by one or two dry ones, or, better still, by a rubber or other impermeable covering, will long retain both heat and moisture, securing free cutaneous circulation, and soothing in a most effective way the irritation in the chest. This may be maintained as long as requisite to relieve the patient, and then the body may be uncovered, a part at a time, rubbed dry and covered with a dry woolen blanket. By using elastic circingles over the compress they are adapted to the respiratory movements and any restriction in the movement of the ribs is beneficial by limiting the friction, pain and irritation in the pleura.
In the second stage, when inflammation has already set in, the same general measures of derivation toward the skin and hot bath or soothing derivative compress are still demanded though they may be substituted by more stimulating derivatives. The bleeding of the patient into his own vessels is sought in various ways. On the continent of Europe stimulating embrocations (essential oils, ammonia and oil, mustard, etc.) are applied to the limbs. In America and England similar agents are more commonly applied to the walls of the chest and dry cupping in the same region has been resorted to. Metallic cups with small mouths and having a capacity of about a pint each, have the air rarefied by plunging into each a spirit lamp, and, on its withdrawal, suddenly applying the mouth of the cup on the skin of the costal region previously well coated with lard. Another form of cup is made with a tube and stopcock in its otherwise blind end by means of which it is exhausted with a syringe after its mouth has been applied to the skin. In the absence of both a narrow mouthed glass tumbler may be employed, the air is rarefied by inserting into it a burning spill of paper or wood for a few seconds and on its withdrawal the cup is instantly inverted on the skin. If the animal is very hairy or very thin it may be necessary to shave the part, and smear with oil and even to select a very narrow mouthed cup. When applied the cup is cooled with water or otherwise and owing to the partial vacuum the skin is strongly drawn up into it and the blood accumulates in and under the skin. It may be kept on for half an hour at a time and with ten or twelve cups on one side the patient tends to profuse perspiration establishing a strong revulsion toward the skin, and great relief. In dangerous cases three or four applications may be required in twenty-four hours.
Next to this the mustard application is perhaps the safest and most valuable. The best ground mustard (black by preference) is made into a very thin pulp with tepid or cold (never hot nor boiling) water and rubbed in against the hair so as to soak the surface of the skin; it is then closely covered with paper and with a rubber or other impervious covering or, in default of better, with a close blanket and left on for two hours. By this time the skin should be thickened to the extent of at least a quarter of an inch and the derivation and relief will be very manifest.
Cantharides is sometimes used but like most other severe irritants, is liable to induce sympathetic irritation in an already severely inflamed pleura, and thus to obviate all benefit. Cantharides is also liable through extensive absorption to irritate the kidneys. To counteract this Bouley gave ½ drachm doses of camphor with alleged good effect.
Some practitioners make local applications of hot water and of aqua ammonia (confined) but unless very closely watched these are liable to destroy the hair follicles and produce permanent blemish.