Pressure ulcers are prevalent and costly, particularly for individuals with impaired mobility and sensation. They are primarily caused by high pressure near bony prominences. Multiple other factors include shear force, friction, temperature, and moisture. Recent research at the University of Pittsburgh was conducted on local cooling effects with respect to skin blood flow. A reduction of skin temperature to 25°C provided a significant benefit to local tissue in healthy controls and subjects with spinal cord injuries. This concurs with prior animal studies which demonstrated reductions in breakdown at lower interface temperatures. Pressure ulcers have been historically managed by providing support surfaces, such as wheelchair seat cushions, to redistribute pressure at the body interface.
Few practical interventions exist to control temperature at this interface; most employ passive cooling methods, which are limited by their inability to modulate applied cooling in response to changes in microenvironment. This studys goal was to develop tightly controlled, local cooling elements for integration into a pressure-redistributing support surface.
A holistic view of temperature control methods in an iterative design process was taken. Features, benchmarks, and design specifications were generated using available information from the literature. Idea generation and subsequent evaluation led to the modification of a multi-cell air cushion capable of controlling temperature in specific high risk areas. Proof of concept experiments were conducted with respect to interface cooling to a target temperature, redistribution of pressure, and heat and water vapor transmission.
The design delivered local cooling over hour-long trials on able-bodied test subjects. No significant difference in skin temperature (p>0.16) was found after 15 minutes of cooling from our target temperature (25°C). The modified cushion showed similar (p=0.79) peak pressure index values when compared to the same cushion design without the cooling elements. A thermodynamic rigid cushion loading indenter mimicked the environmental conditions of the body on our prototype for 3-hour duration tests. Significantly lower temperatures were observed after 1 hour of cooling (p<0.003). No effect was noted for relative humidity. These experiments successfully demonstrated plausible, integrated cooling elements in a multi-cell air cushion for the delivery of local cooling for pressure ulcer prevention.
Identifer | oai:union.ndltd.org:PITT/oai:PITTETD:etd-04042011-113718 |
Date | 24 June 2011 |
Creators | Malkiewicz, Andrew J |
Contributors | Michael L. Boninger, M.D., Patricia E. Karg, MSBME, David M. Brienza, PhD |
Publisher | University of Pittsburgh |
Source Sets | University of Pittsburgh |
Language | English |
Detected Language | English |
Type | text |
Format | application/pdf |
Source | http://etd.library.pitt.edu/ETD/available/etd-04042011-113718/ |
Rights | restricted, I hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to University of Pittsburgh or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. |
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