The industry-wide acceptance of risk assessment scales for pressure ulcers has gotten us accustomed to evaluating risk factors for skin breakdown. The most popular is the Braden Scale which incorporates subscales of sensory perception, moisture, activity, mobility, nutrition, and friction and shear. There are however, other factors which add to pressure ulcer risk which need to be taken into consideration. According to research recently published in the Journal of the American Medical Directors Association, hypotension may be an important risk factor for pressure ulcer occurrence.
It is generally accepted that reduced tissue perfusion plays a major role in development of pressure ulceration. Mechanical loading that is significant enough to cause capillary occlusion can lead to ischemia and cell death if pressure is applied long enough. It stands to reason that reduced blood pressure can raise the risk for cell death over boney prominences, and this was the hypothesis of a group of researchers in Hong Kong.
They studied patients over 65 who stayed in a geriatric convalescent ward during a three month period in 2011. Patients were defined as having a hypotensive episode if there was one or more systolic blood pressure readings less than or equal to 90 mm Hg (normal range for systolic pressure is between 90 and 120 mm Hg). Patients who died were excluded. Other data was collected including functional status, presence of tube feeding and congestive heart failure, and an array of laboratory tests. New pressure ulcers of any stage or site were recorded.
Using a retrospective cohort design, 229 patients were included during the 3 month study period. 17 of these patients developed new pressure ulcers and some developed multiple wounds, with a total of 24 new pressure ulcers. Most new wounds (66.7%) were stage II, and the most common location was over the sacral area (70.8%). Of the 17 patients who developed new pressure ulcers, 10 had hypotensive episodes prior to development of the wound. The authors conclude that hypotension is an important risk factor for pressure ulcer development.
This conclusion makes sense from a physiologic point of view. The skin is the largest organ of the body, and relies on blood circulation for delivery of oxygen and nutrients, as well as removal of toxic waste products. Hypoperfusion over pressure points when exacerbated by hypotension can theoretically accelerate tissue damage. Hypoperfusion is a known cause of tissue damage in other organs such as the brain, kidney, heart, and liver. Skin perfusion pressure (SPP) has already been demonstrated as a predictor of wound healing in chronic lower extremity wounds, and it stands to reason that it can also be a predictor of skin deterioration.
There is still a lot to be learned about who gets pressure ulcers and why. The Braden scale has given us a start in the direction of risk factor detection, but there are other physiological factors that can increase risk for developing pressure ulcers. For example many authorities agree that the dying process can lead to unavoidable skin changes at life’s end (SCALE). The occurrence of pressure ulcers even in the face of risk factor interventions such as pressure redistribution surfaces and turning and positioning plans tells us that we have far to go in both understanding risk factors and developing new intervention technologies.
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The complete reference to this article is: Hypotension Is a Risk Factor for New Pressure Ulcer Occurrence in Older Patients After Admission to an Acute Hospital. Ship-piu Man, Tung-way Au-Yeung. Journal of the American Medical Directors Association (JAMDA) V 14, #8, pages 627.e1627.e5, August 2013.
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