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Information For Physicians
Physiology of Wound Healing
Inflammatory Phase
- Wound Healing cycle starts
- Lasts from injury to 4-6 days
- Edema, erythema, inflammation, pain
- Vessels form clots to prevent excessive
loss of blood and fluids
- Platelets release growth factors to
trigger healing process
- White cells go to area to "clean
up"
Proleferative Phase
- Lasts 4-24 days
- Granulation tissue fills in wound
- Fibroblasts lay network of collagen
in wound bed which gives strength to tissue
- Wound begins to contract - edges pull
together
- Epithelial cells from wound margins
migrate inward to cover wound
Maturation Phase
- Lasts 21 days to 2 years
- Begins when wound has filled in and
re-surfaced
- Collagen fibers reorganize, remodel,
and mature to give wound tensile strength forming scar
tissue
- Scar tissue is only 80% as strong as
original tissue.
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
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.
Wound Care Protocols - Once
the type and etiology of the wound has been identified, and
the factors compromising wound healing have been addressed,
management and care of the patient's wound is based on its
classification. The protocol utilized depends on this classification. The
type of advanced wound care product or technology used depends
on the judgment of the wound care physician. Providing
the optimal wound environment consists of aggressive debridement
of necrotic tissue, identification and eradication of infection,
obliteration of dead space, absorption excess drainage, providing
protection and thermal insulation, and finally maintaining
a moist wound environment.
Wound Classification - Based on the appearance of the wound
it may be classified. Management is then determined by this
classification.
The following are classification examples:
Need pics for each
Necrotic
Infected
Draining
Granular
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