Wound Healing Flashcards
(11 cards)
WOUND HEALING -
INFLAMMATION PHASE
1ST 4 DAYS
hemostasis; phagocytosis of bacteria and necrotic debris; stimulation of fibroblast migration and proliferation
A. clot formation: aggregation of platelets and fibrin meshwork to control bleeding
B. acute inflammation ( neutrophils): phagocytosis of bacteria to prevent infection
C. macrophage infiltration: clear extracellular debris and fibrin; secrete
growth factors which stimulate fibroblasts to migrate to site and proliferate
WOUND HEALING -
PROLIFERATION PHASE
development of granulation tissue ( new vessels and proliferating fibroblasts ), collagen production, epithelial regeneration, and initiation of wound
A. DEVELOPMENT OF GRANULATION TISSUE
1. components: new vessels and proliferating fibroblasts
2. term granulation tissue derives from red ,soft, granular
appearance of wound surfaces
3. process of new vessel formation is called angiogenesis:
mechanisms of angiogenesis ( for reference ):
a. preexisting vessels send out capillary buds
b. primitive vascular cells migrate from bone marrow to wound site
B. FUNCTION OF GRANULATION TISSUE
- new vessels: provide nutrition for regenerating tissues ( epithelium etc. ); leaky so plasma proteins ( fibrin and fibronectin ) pass through and serve as initial “scaffold” for scar
- fibroblasts: produce all of the wound collagen by the end of the phase
C. REGENERATION OF EPIDERMIS
D. WOUND CONTRACTION IS STARTED: myofibroblasts cause wound edges to move together to decrease size of the wound
WOUND HEALING -
MATURATION PHASE
remodeling of collagen, development of wound strength, and completion of wound contraction
REMODELING OF COLLAGEN, AND DEVELOPMENT OF WOUND STRENGTH
WOUND CONTRACTION IS COMPLETED
It may take months for the wounded area to obtain maximal strength (MAXIMAL STRENGTH is up to 80% of strength of the original unwounded skin)
Primary Wound Healing
( healing by first intention )
**Clinician brings edges of wound together with some material e.g. sutures; steri-strips; staples
an example: surgical incision
Secondary Wound Healing
healing by second intention )
**Wound heals on its own
wounds that should heal by secondary wound healing:
large surface wound; too small inflammatory ulceration; infected wound
( e.g. abscess ); infarction ( tissue necrosis ); very small laceration
large wound undergoing secondary wound healing there is more wound contraction (edges of wound move towards the center) which can cause scar to be more disfiguring; healing takes a longer time
SYSTEMIC FACTORS IMPAIRING WOUND HEALING
A. nutritional deficiency
example: protein and vitamin C deficiency inhibit collagen synthesis
B. inadequate blood supply ( due to atherosclerosis )
C. steroid hormone therapy:
inhibit inflammatory process and collagen synthesis
D. diabetes mellitus: 3 problems
patients have impaired blood supply to wounds due to atherosclerosis,
decreased sensation in extremities, and impaired immune function
LOCAL FACTORS IMPAIRING WOUND HEALING
A. INFECTION: MOST IMPORTANT CAUSE IN DELAY IN WOUND HEALING
B. foreign bodies
examples: fragments of glass, steel, or bone
C. debris and necrotic tissue: form physical barrier to growth of new tissue
D. wound motion before sufficient healing
COMPLICATIONS OF WOUND HEALING :
INADEQUATE FORMATION OF GRANULATION TISSUE OR ASSEMBLY OF SCAR
A. wound dehiscence ( wound opens )
most commonly occurs after abdominal surgery due to increased abdominal pressure associated with:
vomiting, coughing, or very dilated loops of bowel resulting from postsurgical lack of bowel peristalsis ( physiological bowel obstruction
note: additional factors increasing risk of wound dehiscence: poor suturing technique; immunosuppression; malnutrition; wound infection
B. incisional herniation
bulging sac within healing or healed abdominal incision due to abdominal pressure
COMPLICATIONS OF WOUND HEALING :
EXCESSIVE FORMATION OF COMPONENTS OF REPAIR PROCESS
A. hypertrophic scar
Raised scar caused by excessive collagen within boundaries of original wound
B. keloid
- excessive collagenous protrusion at scar site, beyond boundaries of original wound; sometimes disfiguring
- individual predisposition for development of keloid
- increased incidence in African Americans
- examples of causes: ear piercing, lacerations, surgery
COMPLICATIONS OF WOUND HEALING :
FORMATION OF WOUND CONTRACTURES
A. excessive wound contraction may result in deformities of an area as well as limitation of motion at a joint
B. commonly seen after burns
COMPLICATIONS OF WOUND HEALING :
FORMATION OF ADHESIONS
inflamed serosal surfaces ( e.g. outside intestinal surfaces ) bind together
Example: collagenous adhesions between inflamed loops of bowel can result in bowel obstruction; patient can present with an acute onset of severe abdominal pain, and it is important to determine that the patient had previous history of abdominal surgery
