In every patient suffering from chronic diffuse nephritis there are a number of symptoms which seem to depend directly upon other conditions, and not upon the kidney lesions; for if these conditions are removed the symptoms disappear, although the kidney lesions continue. To this category of symptoms seem to belong the headache, delirium, stupor, coma, and convulsions, the nervous dyspnoea, the vomiting in part, the dropsy in part, the diminution of urine in part. All these symptoms are due to disturbances of the circulation, and the disturbances of the circulation are produced by a number of causes which may act separately or together. Changes in the valves and walls of the heart, in the force and regularity of the heart's contraction, in the walls and size of the arteries and capillaries, and in the volume and composition of the blood, each, separately or associated, may interfere with the proper circulation of the blood, and this interference usually takes the form of too much blood in the veins and too little blood in the arteries.
Anatomical changes in the valves of the heart, in its walls, and in the walls of the arteries and capillaries cannot be influenced by any means at our command. The force and regularity of the contractions of the heart can, however, be very decidedly modified by drugs. Opium in moderate doses makes the heart's action slower and stronger; iodide of potassium makes the heart's action more regular; convallaria makes the heart's action slower and stronger; digitalis increases the force of the heart's action, but at the same time contracts the arterioles; aconite and veratrum viride make the heart's action slower and more feeble.
The size of the arteries and capillaries can also be altered by drugs. Nitrite of amyl and nitro-glycerin relax and dilate the whole arterial and capillary system; chloral hydrate dilates the arterioles (Fothergill).
The volume of the blood can be diminished by bloodletting and by eliminating the plasma of the blood indirectly by sweating, purging, or diuresis.
The symptoms which can be ascribed directly to the presence of the kidney disease are—(1) The changes in the composition of the blood. We have still very little exact knowledge of what these changes are, but we may say generally that there is an increase in the relative quantity of the watery constituents of the blood and of the excrementitious products which should be eliminated by the kidneys. (2) The changes in the quantity of urine probably depend partly on the changes in the circulation, partly on the composition of the blood, and partly upon the structural changes in the kidneys. The albumen and casts seem to be directly due to the kidney lesion. (3) The changes in the nutrition of the patient, the disturbances of digestion, and some of the headaches, all seem to belong directly to the kidney disease.
Now let us try to apply these principles to the practical treatment of the different symptoms.
The Urine.—As regards the presence of albumen and casts, it is doubtful whether we are able to do anything, although it is customary to give the tr. ferri chloridi and the bichloride of mercury in order to diminish the excretion of albumen. As regards the quantity of urine, we must distinguish whether the patient is in the ordinary course of the disease, whether he is having an uræmic attack, or whether he is having an acute exacerbation of the nephritis with congestion of the kidney and blood in the urine. Under the circumstances last mentioned the indications are to apply wet or dry cups over the lumbar region, to use hot fomentations to the back or hot-air baths, to open the bowels freely, to put the patient on a milk diet, and, if the heart's action is too strong, to give aconite in small doses.
If during the ordinary course of the disease the urine is constantly diminished, diuretics are often of good service, although the cases differ as to the particular drugs which answer best. The preparations of digitalis, the diuretic pill of digitalis, squills, and bichloride of mercury, the iodide and acetate of potash, and jaborandi in small doses, are the most reliable agents of this class. Sometimes the frequent use of milk or of water in small quantities (half an ounce or an ounce every half hour) will answer the purpose. There can never be any use in continuing the employment of diuretics in these cases if after a fair trial they do not increase the flow of urine.
During the progress of uræmic attacks diuretics do not act, and the same is often the case with cathartics and diaphoretics. The urine is only to be increased by the same means which are indicated for the relief of the whole uræmic condition, and of these we will speak later.
The dropsy in many cases will vary in amount, and even disappear at times without any treatment. It is regularly most marked with the large white kidneys and with those kidneys which are neither large white nor atrophied, especially when there is complicating heart disease and the patient is anæmic. Generally speaking, it is best to keep dropsical patients in bed most of the day. We attempt to get rid of the oedema by the skin, the bowels, and the kidneys, to regulate the heart's action, and to improve the condition of the blood. Hot-air baths or hot-water baths repeated every day, the milder hydragogue cathartics, and the different diuretics may all be used with advantage. If the dropsy is excessive, it may be necessary to tap the peritoneal or pleural cavities or to puncture the skin of the legs and scrotum. Sometimes bandaging the legs so as to exert moderate pressure seems to assist in getting rid of dropsy. To regulate the heart's action we find that digitalis, convallaria, and the iodide of potash are often of service. To improve the condition of the blood the systematic use of iron and oxygen is indicated. The most hopeless cases are those in which there is complicating heart disease and those in which the dropsy steadily increases, although the patient is passing from 60 to 100 ounces of urine daily.