Eschar is a pathological product that develops during the wound healing process. There are different forms of eschars that can be characterized by a variety of features. Based on the texture, eschars can be divided into the following categories: eschar (Figure 3A), tough (Figure 5A), soft (Figure 1A), and putrid (Figure 6B). When pressed, the eschar may exhibit floating (Figure 7A), undulation (Figure 1A), flexibility (Figure 4A), or solidness (Figure 2A). The color of eschar is determined by the components that it is comprised of, such as yellow for serous eschars, green-yellow for purulent eschars, dark red for eschars with blood, and white for ischemic eschars. Eschar color also can be affected by the inclusion of chemicals. The eschar boundaries may be clear, cloudy, or opaque with regular, less regular, or irregular edges. The eschar surface may be smooth, rough, flat, bumpy, or concave. Furthermore, eschars may form different shapes such as mammilla-like, cauliflower-like, or hemispheric. The contents under the eschar may include blood, seriflux, purulence, sebum, or cutin. Eschars may be singular; multiple arranged in a line, band, or circle; or irregular multiple areas. During eschar palpation, the size, shape, thickness, firmness, and fluctuation of the eschar are examined in addition to local skin temperature, local adhesion, pressing pain, and paresthesia. Here, the authors discuss the therapeutic approaches employed to treat eschars at their center.
Gradual eschar excision therapy for toe ulcers
Because the corium layer of toe skin is thin and rich with underneath structures, infection can easily spread from the toes to the central part of the foot (Figure 3A). If the degree of under-eschar infection cannot be determined, a fenestration or excision of the turn-up edge of the eschar may help; if combined with drainage and symptomatic treatment, the infection can often be confined. If the under-eschar infection only has small amounts of purulent exudates, an expanded debridement is unnecessary; however, these cases can evolve into dry gangrene and coexist on the toe for a prolonged period. Fenestration may be the best choice for patients with poor systemic conditions or patients who refuse amputation. Furthermore, fenestration prepares the patient for further interventional procedures or amputation.
Immediate eschar excision for central foot ulcers
The subcutaneous tissues of the central foot, such as muscle, tendon, and fascia, are loosely arranged and the blood supply is rich because of the arcus arteria dorsalis pedis. This anatomy enables the spread of infection through the tissue space. The primary purpose of treatment is to maintain drainage and thereby prevent the spread of infection, avoiding amputation.
As shown in Figure 4A, ulcers can be affected by moist gangrene. To confine the infection and stop necrosis expansion in such cases, the authors excised the entire eschar with drainage, which should limit local inflammatory damage and the systemic inflammatory impacts, such as excessive inflammatory consumption and septic reaction. Wound drainage prevents inflammatory damage to tissues around the ulcer and prevents further inflammatory invasion. When moist gangrene is present, amputation should be considered to eliminate risks to the patient’s life.
In case 2, the inflammation resolved gradually, and granulation tissue proliferated at the base of the ulcer, which created favorable conditions for further treatment. Conversely, in case 1 (Figure 3A), the turn-up edge of the eschar was excised, and the eschar was firmly adhered to subcutaneous tissue without inflammation and exudation. If the entire eschar had been excised immediately, the ulcer would have had a higher chance of infection, potentially leading to aggravation of the ischemia and expansion of inflammation, thus possible urgent amputation.
Precise eschar excision for ankle ulcers
The ankle is a junction between the foot and the tibia and fibula as well as an aggregate region of tendons. Ankle skin is thin, and the corium layer makes direct contact with bones without any subcutaneous tissues. Therefore, an ulcer infection can spread easily, destroy the joint capsule and bones, and may even cause osteomyelitis, all strong risk factors for amputation.
In case 3 (Figure 5A), the authors first excised the edge of the eschar and found the inflammatory damage was relatively superficial. After precise eschar excision with drainage, the infection resolved and the wound healed. The ulcer in case 1 (Figure 3A) also was superficial but was complicated by severe ischemia and poor local circulation. To treat this patient, the eschar was excised gradually, the wound was kept dry, and the ulcer was allowed to coexist on the toe for a prolonged period. If the entire eschar had been excised immediately, the wound would have been expanded. In addition, the local ischemia would have worsened, potentially leading to further damage.
Conservative treatment for heel ulcers
The skin of the heel is thin, but the subcutaneous space is filled with a thick layer of fatty tissue. If infection from the ulcer invades the fatty tissue, rapid necrosis of the entire layer occurs, which destroys the calcaneus and can even cause osteomyelitis (primary amputation risk factors).
The ulcer in case 4 (Figure 6A) was severely ischemic with poor local circulation, which limited the infection. The ulcer was treated with basic symptomatic treatment to improve local blood circulation rather than excising the eschar immediately. When the local circulation improved, the authors began to excise the eschar gradually.
Therapeutic approaches for crus ulcers
The treatments utilized for pretibial and posterior tibial ulcers are different. Because the blood supply of the posterior tibial region is rich, and the subcutaneous tissue is thick, posterior tibial ulcers can heal easily following excision with drainage (Figure 6A). On the other hand, the subcutaneous tissue of the pretibial region is thin, indicating the eschar should be excised with care to prevent bone damage.
In case 5, the eschar was excised gradually and the wound was kept dry, allowing the ulcer to coexist on the crus for a prolonged period of time.
Debridement
Before debridement, the treatment goals must be determined based on the degree of local ischemia and infection as well as ulcer location. When amputation cannot be avoided, an enlarged debridement is needed to drain necrotic tissue and prevent a systemic reaction in preparation for amputation. If amputation is not considered to be an option, debridement should be limited to providing wound drainage. In the event that the infection invades the surrounding tissue or shows signs of spreading, debridement should be limited to the wound area because the necrotic tissue may provide a barrier that can confine the injury.