An acute wound can be defined as an unplanned disruption in the
integrity of the skin, including the epidermis and dermis. The goals
of wound management are to restore tissue continuity and function,
minimize infection, repair with minimal cosmetic deformity, and
be able to distinguish wounds that require special care. The principles
of wound management should be emphasized over the repair technique.
Appropriate wound management prior to approximating the wound will allow
it to heal with minimal complications. This includes wound cleansing,
debridement of the wound edges, wound approximation, and prevention
of secondary injury.
The response of tissue to an injury is described in three phases.
The first phase is coagulation and inflammation. The second phase
is the proliferative phase. The final phase is the reepithelialization
or remodeling phase.
Phase I consists of coagulation and inflammation. It occurs in
the first 5 days. This phase is also known as the vascular phase.
A fibrin clot forms a transitional matrix that allows for the migration of
cells into the wound site over a period of 72 hours. Inflammatory
cells (i.e., neutrophils, monocytes, and macrophages) kill microbes,
prevent microbial colonization, break down soluble wound debris,
and secrete cytokines. The cytokines signal synthetic cells, such
as fibroblasts, to initiate phase II.
Phase II is the proliferative phase. It occurs during days 5
to 14 after the injury. Fibroblasts proliferate and synthesize a
new connective tissue matrix that replaces the transitional fibrin
matrix. Granulation tissue consisting of fibroblasts, immature connective
tissue, epidermal cells that have migrated, and abundant capillaries
forms within the wound. Fibroblasts release collagen, a protein substance
that is the chief constituent of connective tissue. At 5 days, the tensile strength of the
wound itself is 5 percent that of normal skin. Collagen formation
peaks at day 7.
Phase III is known as the remodeling, reepithelialization, or
maturation phase. It occurs from day 14 and lasts until there is
complete healing of the wound. The new granulation tissue is being
converted into a scar. The scar consists of a rich matrix with decreasing
cell density, decreasing vascular density, and increasing thickness
of collagen fiber bundles packed in parallel arrays.1The wound will have 15 to 20 percent of
its full strength at 3 weeks and 60 percent of its full strength
at 4 months. Tensile strength continues to increase up to 1
year after wounding. The skin will eventually regain 70 to 90 percent
of its original tensile strength.
Factors Affecting Normal Repair
The most common causes of improper wound healing are tension
on the wound edges, necrosis and/or ischemia of the tissues
from local conditions (crushes and contusions decrease blood flow and
lymphatic drainage, which alters local defense mechanisms), or shock.
Hypovolemia is the major deterrent to wound healing in patients
with hemorrhage and shock, hemorrhage from inadequate hemostasis,