1. Wound Healing- Part I
Frequently, presenters must deliver material of a technical nature to an audience unfamiliar with the topic or vocabulary. The material may be complex or heavy with detail. To present technical material effectively, use the following guidelines from Dale Carnegie Training®.
Consider the amount of time available and prepare to organize your material. Narrow your topic. Divide your presentation into clear segments. Follow a logical progression. Maintain your focus throughout. Close the presentation with a summary, repetition of the key steps, or a logical conclusion.
Keep your audience in mind at all times. For example, be sure data is clear and information is relevant. Keep the level of detail and vocabulary appropriate for the audience. Use visuals to support key points or steps. Keep alert to the needs of your listeners, and you will have a more receptive audience.
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2. Why Study Wound Healing?
50 million surgical procedures performed each year in the US alone;
Recovery from these procedures conservatively requires 250 million patient days in lost productivity and billions of dollars in lost or supplemental earnings;
Despite the technical advances, complications resulting from surgery has not declined over the past 50 years;
The wound healing response affects implant performance:
Blocks flow in catheters, cannulas and infusion pumps;
Forms impedance barriers around electrodes, drug delivery systems
Degrades polymeric materials; and,
Thrombus formation blocks dialysis membranes and vascular grafts,etc.
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3. Wound Healing The process of repair
A cascade of events that involves the interaction of various cellular and molecular components that act in synchrony to effect wound closure by forming new tissue.
The process can be understood as progressing through multiple stages, but realistically takes place as a continuum.
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4. Normal Tissue Multi-cellular Three-dimensional structures
Extracellular Matrix
Multi-functional
Takes cues from the environment
Interface with surroundings
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5. Tissue Injury Results in a variety of cellular responses including:
Necrosis (death by extrinsic means)
Apoptosis (death by suicide)
Atrophy (decrease in cell size and/ or function)
Hypertrophy (increase in cell size)
Hyperplasia (increase in cell numbers)
Metaplasia (change in cell type)
Change in phenotype (change in the type and/or amount of protein characteristic of a particular cell type)
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6. Different Tissues have Different Capacities to Heal
Regenerative capacity varies:
High capacity
epithelial, lymphoid, hematopoietic, mesenchymal tissues (cell types include fibroblasts, smooth muscle cells, osteoblasts, chrondrocytes, and endonthelial cells)
Highly vascularized
Low capacity
Nerve, muscle (skeletal and cardiac), cartilage
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7. The Biology of Wound Healing -Vascularized Tissue
Most of what we know has come from studies in skin of adult mammalian species;
In general, wound healing proceeds slower and with more scarring as a function of increasing age
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8. From a Bioengineering Perspective
A series of time-dependent reactions that integrate into an expected outcome of resolution or scar formation;
Each event follows a predictable temporal pattern;
Perturbations to any event predictably lengthen the amount of time required for normal healing;
These may include the size of the wound, the amount of contamination or infection, the degree of vascularization of the tissue, presence of a foreign body, and the general health & age of the patient;
The process can be conceptualized in terms of a set of processes whose mathematical trajectory can be measured and modeled over time.
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9. Sequence of Events Following Device Implantation:
Injury
acute inflammation
chronic inflammation
granulation tissue
foreign body reaction
fibrous encapsulation
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10. Sequence of local events following implantation
Injury
Injection, implantation
Acute inflammation
Polymorphonuclear leukocytes
Chronic inflammation
Monocytes and lymphocytes
Granulation tissue
Fibroblasts and new blood capillaries
Foreign body reaction
Macrophages and FBGCs at the material-tissue interface
Fibrosis
Fibrous capsule
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