Factors that Impair Wound Healing
Foreign material. Foreign material is everything the host. organism’s immune system views as non self, including bacteria, dirt, suture material, and so on. Foretgn materials cause three basic’ problems. First, bacteria
can proliferate and cause an infection in which’ bacterial proteins that destroy host tissue are released. Second, non bacterial foreign material acts as a haven for bacteria by sheltering them from host defenses’ and thus promoting infection. Third, foreign material is often antigenic and can stimulate a chronic inflammatory reaction that decreases fibroplasia.
Necrotic tissue. Necrotic tissue in a wound causes two problems. The first is that its presence serves as a barrier to the ingrowth of reparative cells. The inflammatory stage is then prolonged while white blood cells to .rernove the necrotic debris through the processes ‘of enzymatic lvsis
and phagocytosis. The second problem is that, similar to foreignmaterial, necrotic tissue.serves as a protected niche for bacteria. Necrotic tissue frequently includes blood that collects in a wound (hematoma), where it can serve as an excellent nutrient source for bacteria.
Ischemia.’ Decreased blood supply to a wound interferes with wound repair in several ways. It can lead to further tissue necrosis and also lessen the delivery to a wound of antibodies, white blood cells, and antibiotics,
which there increases the chances of wound infection. Wound ischemia decreases the delivery of oxygen and the nutrients necessary for proper healing. Ischemia can be caused by several things, including .tight or incorrectly located sut.ures, improperly designed flaps, excessiveexternal pressure’ on a wound, internal pressure on a wound (seen, for example, with hematomas), systemic hypotension, peripheral vascular disease, and anemia.
Tension. Tension on a wound is the final factor that can impede wound healing. Tension in this case is anything tending to hold wound edges apart. If sutures are used to overcome excessive wound tension, the tissue
encompassed by the sutures will be strangulated, producing
ischemia. If sutures are removed too early in the healing process, the wound under tension will probably reopen and then heal with excessive scar formation and wound contraction. If sutures are lE~ftin too long in an
attempt to overcome wound tension, the wound will still tend to spread open during the remodeling stage of healing, and the tract into the epithelium through which the sutures ran will epithelialize and leave a permanent disfiguring mark.