Moist Gangrene. When a part which has had its vitality seriously interfered with becomes gangrenous, pain, which may have been present, suddenly ceases, the part becomes insensitive, and the skin is cold, pale, and mottled purple, green, and red, and finally dark colored; blebs containing brownish serum form upon the surface; the wound, if one is present, assumes a grayish color, and an offensive discharge escapes from it; the dead tissue rapidly undergoes putrefactive changes. Coincidentally with these changes in the dead tissues, the living tissue in contact with it becomes red and swollen, and the separation of the dead tissue from the living is affected by an ulcerative inflammation, granulations from the living tissue lifting off the slough.
The patient, at the same time, if the gangrenous process involves any considerable extent of surface, exhibits the unconstitutional signs of inflammation (fever, rapid pulse, etc.) and, in some cases, if the septic infection is intense, may die from septicemia.
In both dry and moist gangrene, when the gangrenous process is arrested, the dead tissue is separated from the living by a process of inflammation; the living tissue, at its point of contact with the dead tissue, and for some distance from it, becomes red and swollen, and exhibits all the signs of acute inflammation. The line of contact between the dead and the living tissue is known as the line of demarcation, and the line of granulations which separates the dead tissue from the living, is known as the line of separation.
The separation of the dead tissue is affected by granulations, which spring up from the living tissue as a result of inflammation, and there is also a certain amount of pus secreted from the granulations. In moist gangrene, the lines of demarcation and separation are fairly well developed. In dry gangrene, on the other hand, these lines are usually imperfectly developed.
Early Diagnosis. From the foregoing it will be observed that gangrene is most common in those past middle life, and that its actual onset is only a stage in an insidious process. This may be either due to senility or to some constitutional disease. A slight abrasion alone is sufficient to set up a train of symptoms out of all proportion to the cause. In such a case, the operation of a small verruca or papilloma may be followed by a violent inflammatory reaction, with rapid extension into the entire foot or leg, resulting in gangrene.
Such cases have occurred, but could have been prevented if a proper survey of the field had been taken and would have saved the chiropodist much responsibility.
Before operating on subjects past middle life, it should be a routine practice to note the color and temperature of the foot, both in the dependent and horizontal positions. The anterior tibial pulse should also be felt for and its absence or intensity noted. A question to the patient as to diabetes or thickened arteries may also elicit valuable information. A very weak or absent anterior tibial pulse (the knack of feeling the pulse here must be acquired), or peculiar nodules about the nail grooves, are evidences of an encumbered arterial supply.
Extreme redness or blueness in a foot in the hanging position, and pallor when elevated, also indicate a similar condition, or one in which the valves in the veins are impaired.
It is in such conditions that the greatest care should be taken to avoid deep incisions except in the presence of positive indications.