When a part has been exposed to much cold, it may inflame, from two causes: First, the communication of action; secondly, the application of subsequent stimulants, more especially heat. Both of these tend to excite an action in the part, which is greater than its power would naturally perform, and, therefore, it becomes diseased, or inflammation is produced, and the little energy which did remain is soon destroyed. The operation of the first cause is prevented by lessening the action of the surrounding parts, by the application of moderate cold, whilst we avoid motion, and whatever may tend to act directly on the part, and co-operate with this cause. The operation of the second cause is prevented by keeping away every agent which will tend to excite action, or at least those which tend to do so suddenly. In the generality of cases, it is perhaps most proper at first to do nothing; because, whatever we apply, tends to excite a greater action than can be sustained; we ought, therefore, to delay any remedy until the part has begun to recover itself, and the action and corresponding power has begun naturally to increase; we may then interfere, by applying such remedies as increase the action, which are perhaps now more useful, by preserving the ground which is gained, than by increasing still farther the action. Of this kind is heat, which must, upon this principle, be applied with great caution, and must, in its degree, be nicely adjusted to the existing state of action. When a part, then, is benumbed with cold, we ought at first to apply a degree of heat, very little above that which the parts were formerly exposed to, which, in one sense, may be said to be doing nothing; for this step is intended merely to prevent farther injury. When this is continued for a short time, we may suppose that the part has begun to act a little more in a natural way, which is attended, as was formerly explained[69], with a correspondent increase of injury. We then increase the heat, but very slowly, and taking a long time to bring the part near its natural temperature, being regulated by the progress which the part itself is making; for the application of heat may be considered in two points of view, in this case; first, as the removal of the injuring cause; and, secondly, as a stimulus to action. If, then, the part do not recover itself, in proportion to the removal of the hurtful cause, but remain stationary, it is evident that a farther removal is at present useless, and the stimulus which is consequently given is highly dangerous. By these means, then, we proceed slowly toward recovery, and keep up the ground which we have gained.
If, however, the action of the part have been sunk very low, then recovery is impossible, there being little or no energy, and so little action, that it cannot increase itself toward the natural state. In this case, our endeavours must fail, and will even kill the part sooner than if we had let it alone; for the least increase of action destroys the life of the part, which may, in this case, be compared to a dying taper, which gives one brighter flash before it becomes for ever extinguished.
If, on the other hand, the action have not originally been sunk so low as to make the process toward death continue progressively, but the remedies have been applied too quickly, or, from any cause, have failed to produce this effect, then the action becomes inflammatory. The pain becomes of a burning kind, there is a feeling of pulsation, and the part becomes redder, or livid, whereas, before, it was bluish; from the stagnation of the blood, there was no feeling of pulsation, or arterial motion, and the sensation was that of a painful cold and weight. The inflammatio debilis is now induced, and the danger is great, but still there is a possibility of recovery, which is exactly in proportion to the degree of previous diminution of action, and to the rapidity with which the subsequent inflammatory action was induced, and the degree to which it is raised; or, in other words, the danger is proportioned to the disparity betwixt the action and the power.
The remedies for this disease are such as tend to induce an action similar to the natural one, by which we remove the diseased one; for we know of none which excite the natural action directly, otherwise they would be of universal utility, and would, in the present instance, be preferred to every other. The remedies which we employ with this intention, are bark, opium, &c. internally, and vinous, or spiritous applications externally. These, however, would be pernicious, were there no inflammation present, because they would, by exciting action, tend to induce this; but, when, the inflammatory action is once induced, then, as they excite one more nearly resembling the natural one, they are useful; for, on the one hand, they destroy the morbid one, and, on the other, increase the power of recovery; but, for this purpose, internal medicines, and good diet, must be given, as a source whence the energy is to be renewed, by the renewal of the natural action. Heat is of the most pernicious tendency in this complaint; because it simply increases the exciting action, and, therefore, makes the inflammatory action still more violent. The applications, therefore, ought to be cold, as long as the morbid action continues; but, when it is abating, and recovery is going forward, they may be made a little warmer, as they will thus accelerate the healing process which is taking place; but this requires much prudence.
Spirit of wine is one of the best applications in this disease, and is one very generally employed. Camphor is frequently added to it, and appears to increase its efficacy. Pledgets dipped in camphorated spirit of wine, and applied to the part, will, if frequently renewed, in many cases, remove the inflammation, and prevent gangrene; but, in every instance, it at least relieves the pain, which uniformly returns, if, when the inflammation is violent, we omit the application, or use a weaker spirit, such as the proof spirit.
Essential oils, particularly that of turpentine, which is easiest procured, are also useful, but are inferior to the alcohol.
Laudanum, in slight cases, is useful as a topical application; but, if the inflammation be more severe, it must be mixed with rectified spirit. A very useful application may be prepared by adding two ounces of laudanum to a pound of the spt. vin. camph. of the pharmacopœia.
Internally, the bark must be exhibited in full doses, with such a quantity of wine as the feebleness of the pulse points out; but we must be prudent in this respect, because, if we give too much, we may increase the local disease. As long as it does not increase the pain, or quicken the pulse, it is to be considered as useful.