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9 Cards in this Set
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Patients with advanced arterial insufficiency have impaired tissue oxygenation as part of the disease process
Bc the amt of O2 reqd to promote wound healing is significantly greater than than needed to maintain tissue quality, once tissue damage has occurred, arterial ulcers are likely to progress |
The primary cause for arterial insufficiency is arteriosclerosis--thickening and hardening of arterial walls
Atherosclerosis is the most common form of arteriosclerosis--it is a systemic process in which the arterial lumen is progressively encroached upon causing arterial stenosis |
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Vessel stenosis progresses gradually in most cases, slowly decreasing the amount of O2 and nutrients delivered to tissues perfused by the affected vessels
This decreased blood supply may no longer be able to meet tissue demands One of the first signs of AI is Intermittend Claudication--which is activity dependant discomfort d/t local ischemia |
Risk factors contributing to AI:
1. Hyperlipidemia (High Cholesterol) 2. Smoking 3. Diabetes 4. Hypertension 5. Trauma 6. Advanced age |
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Patients with advanced arterial insufficiency have impaired tissue oxygenation as part of the disease process
Bc the amt of O2 reqd to promote wound healing is significantly greater than than needed to maintain tissue quality, once tissue damage has occurred, arterial ulcers are likely to progress |
The primary cause for arterial insufficiency is arteriosclerosis--thickening and hardening of arterial walls
Atherosclerosis is the most common form of arteriosclerosis--it is a systemic process in which the arterial lumen is progressively encroached upon causing arterial stenosis |
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Vessel stenosis progresses gradually in most cases, slowly decreasing the amount of O2 and nutrients delivered to tissues perfused by the affected vessels
This decreased blood supply may no longer be able to meet tissue demands One of the first signs of AI is Intermittend Claudication--which is activity dependant discomfort d/t local ischemia |
Risk factors contributing to AI:
1. Hyperlipidemia (High Cholesterol) 2. Smoking 3. Diabetes 4. Hypertension 5. Trauma 6. Advanced age |
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Although arterial ulcers can develop spontaneously d/t decreased tissue perfusion--trauma is a common precipitating factor
The increased metabolic demand of tissues resulting from minor trauma may be enough to disrupt the delicate balance between tissue repair and tissue breakdown |
Calf muscle pump assists with blood flow in the venous system by compressing the deep veins--which increases the pressure within the deep veins--forcing blood proximally up the leg
When the calf muscles relax, venous pressure is decreased & the valves prevent retrograde blood flow |
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Fibrin Cuff Theory of Venous Insufficiency:
Vessel hypertension and distension cause an increase in vascular permeability As a result fluid and proteins are allowed to move from within these vessels into the interstitial tissues causing peripheral edema Once within the interstituim fibrinogen is converted to fibrin--fibrin adheres to the capillary walls forming a "Cuff" The cuff poses a barrier to the exchange of O2 and nutrients causing local hypoxia and malnutrition |
White Blood Cell Trapping Theory of Venous Insufficiency:
Venous hypertension and distension cause congestion--decreased blood flow through the veins and capillaries causes margination of WBCs WBCs adhere to teh vessel walls, further impeding circulation--once adhered or "trapped" WBCs become activated beginning the inflammatory process WBCs then move into the interstitium releasing enzymes, free radicals, & other inflammatory substances which further contribute to endothelial cell damage Thus, ulceration results from local hypoxia, WBC trapping, and the increased demands placed on affected tissues by the ensuing inflammatory response |
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It is thought now that both the Fibrin Cuff Theory and WBC Trapping Theory play a role
What is known is that the main cause of skin and tissue breakdown is hypoxia secondary to venous hypertension |
Risk factors for Venous Insufficiency Ulcer:
1. Vein Dysfunction 2. Calf muscle pump failure 3. Trauma 4. Diabetes 5. Age 6. Previous Venous Insufficiency Ulcer |
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Trauma to an area of venous insufficiency, even if its very minor, may be just enough of an overload on an already taxed system to cause ulceration
The presence of edema occurring after trauma increases the diffusion distance for O2 and nutrients Once a break in skin integrity occurs, the likelihood of delayed wound healing is increased because oxygen is critical to each phase of the wound |
Pressure ulcers are localized areas of tissue necrosis that develop when soft tissue is compressed bt a firm surface and an underlying bony prominence
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When the applied pressure is greater than the intracapillary blood pressure, blood flow to soft tissue is obstructed and local tissue ischemia occurs
The applied pressure also obstructs local lymphatic channels--restricted blood and lymph flow leads to higher concentrations of metabolic wastes and acidosis, increasing the rate of cell death Capillary permeability increases as does local inflammation and edema exacerbating the local circulation and increasing the amt of tissue necrosis |
Capillary Closing pressure is thought of as a critical level of pressure, below which no ulceration will occur (13-32 mm Hg)
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