Indications for the sedative effects of cold are offered in vascular or nervous excitement, in abnormal elevation of temperature, and sometimes when it may be desirable to lessen sensitiveness to pain.

In using means to fulfil these indications, it is necessary to bear in mind the tendency to reaction under the influence of cold. This must be overcome when the object aimed at is purely depression. Hence, one general rule is to continue the application of cold steadily until the object for which it is applied is accomplished, or until there is greater danger of evil than expectation of good from perseverance with the remedy. its intermittent application, during the continuance of the nervous or vascular excitement which it is employed to subdue, might endanger an increase of the affection, through the excitement of the intervening reaction. At least, one effect would counteract the other; and, if evil might be avoided, no great advantage could be looked for. This rule is peculiarly applicable to the use of cold as an antiphlogistic agent.

Another important practical rule is always to take into consideration the strength of the patient, and to proportion the degree of cold accordingly; a much less reduction of temperature being in general necessary or admissible in a/patient of impaired health, and feeble powers of reaction, than in the robust.

The various modes of applying cold have already been sufficiently treated of, unless where some peculiar method may be called for in a special affection. With this exception, therefore, it will be sufficient to refer the reader to the remarks upon cold as an astringent (i. 108), as a tonic (i. 194), and as a nervous stimulant (i. 587).

3. Therapeutic Application

Cold is employed internally or externally, or in both methods conjointly, in acute inflammations, high vascular irritations or active congestions, fevers, diseases of nervous excitement, and as an anaesthetic agent.