Phases of Wound Healing
Wound Healing occurs in three phases: inflammatory, proliferative and maturation.
The key cells in the healing process are the macrophages and the fibroblasts. Macrophages engulf and destroy bacteria and clean the wound site of debris. Fibroblasts synthesize collagen, the principle component of connective tissue.
Acute wounds in the non-compromised host progress through the 3 phases of healing without delays. However, chronic wounds stagnant between the inflammatory and proliferative phases. Chronic wounds may be present from weeks to years and require a comprehensive approach to therapy in order to accomplish healing. Chronic wounds are oftentimes compromised due to vascular insufficieny. This causes tissue ischemia and hypoxia, which lead to loss of vascular membrane integrity, which results in edema. Tissue edema can then cause further vascular insufficiency and the start of a vicious downward spiral for the patient. During the early phases of wound healing (inflammatory & proliferative) the metabolic and oxygen demands of the wound can increase by a factor of 20 or more. Macrophages, fibroblasts and all 3 wound-healing phases are oxygen dependent and tissue oxygen tensions above 30mmHg are needed for collagen synthesis. Hyperbaric Oxygen can assist in increasing tissue oxygenation when patients are compromised due to end-stage vascular disease.
Principles of wound healing include supporting the fluid and nutritional intake of the patient in addition to gaining control of systemic factors affecting wound healing. The wound care team must address vascular compromise and maximize blood flow; reduce the mechanical problems of pressure, shear, and friction, and control moisture and infection. A healed wound will eliminate pain, improve the quality of life, and is cost effective.