Technology and product reviews


cycle preferable. While cycle frequency and duration is important, the most significant benefit is attributed to cycle amplitude, with complete or near complete off-loading delivering superior tissue perfusion compared with partial off- loading[14][17]


. References


16.Makhsous M, Priebe M, Bankard J et al. Measuring Tissue Perfusion


During Pressure Relief Maneuvers: Insights Into Preventing Pressure Ulcers. J Spinal Cord Med, 2007; 30(5): 497–507.


17. Goossens RH, Rithalia SVS.


Physiological response of the heel tissue on pressure relief between three alternating pressure air


mattresses. J Tissue Viability, 2008; 17(1): 10–14.


18. Gunther R, Clark M. The effect of a dynamic pressure redistributing bed support surface upon system lymph flow and composition. J


Tissue Viability, 2000; 10(3 suppl.): 10–15.


19. Rithalia SVS, Heath GH,


Gonsalkorale M. Assessment of alternating-pressure air


mattresses using a time- based pressure threshold technique


and continuous measurements of transcutaneous gases. J Tissue Viability, 2000; 10: 13–20.


20. Tissue Viability Society. Laboratory measurement of the interface


pressure applied by active therapy support surfaces: A consensus


document, J Tiss Viab. 2010; 19(1): 2–6.


21. Iglesias C, Nixon J, Cranny G et al. Pressure relieving support surfaces (PRESSURE) trial: cost-effectiveness analysis. BMJ, 2006; 332(7555): 1413–15


22. Fleurence R. Cost-effectiveness of pressure-relieving devices for the prevention and treatment of


pressure ulcers. Int J Technol Assess Health Care, 2005; 21: 334–41


23. Clark M. Models of pressure ulcer care: costs and outcomes. Br J Healthcare Management, 2001; 7(10): 412–16


24. X EPUAP-NPUAP treatment


guideline. 2009. Available at: www. epuap.org (Accessed on 21 August)


25. Stockton L, Rithalia SVS. Is


dynamic seating a modality worth considering in the prevention of pressure ulcers? J Tissue Viability, 2008; 17(1): 15–21


STANDARDISED PERFORMANCE MEASUREMENT One or more of the performance characteristics for each device, be it a mattress replacement, mattress overlay or chair cushion, will almost certainly be different. Even subtle changes, particularly those that control the duration and amplitude of the loading/off-loading cycle, have been shown to elicit very different physiological responses in systems, such as lymph flow[18] and perfusion[19]


. A study comparing pressure


and tissue perfusion at the heel [Fig 3], while subjects lay on three virtually identical mattress replacements[17]


, clearly demonstrated a


significant relationship between performance (amplitude and off-loading) and outcome. It is clear that, despite similar physical


construction (appearance), performance differences may have important implications for clinical prescription. These have yet to be fully investigated but are likely to depend on the underlying condition of the patient and the individual therapy goals. For example, if a patient has very slow reperfusion then a longer cycle might be preferable; if the patient had pain or muscle spasm then a low amplitude cycle might be better Unfortunately, at present, clinicians cannot


objectively and fully assess how a support surface might perform, how ‘active’ the therapy actually is, how it might compare with their existing surfaces and how best to select the right surface for a specific clinical application in the future. Once the surfaces are properly described


the results of clinical studies are much more meaningful. Clinicians can select a device with the same or similar performance characteristics and have perhaps more chance of getting similar results than they do at present. For example, if a surface with particularly


good results in heel ulcer treatment is accurately described the clinician has a much greater chance of finding a similar product. Today they only have appearance, price and marketing brochures to guide them in many cases. Data arising from, non-standardised test


conditions can be unreliable and, therefore, misleading. Clinicians need access to information collected under controlled test conditions in order to tailor prescriptions, design and report clinical


6 Wounds International Vol 3 | Issue 3 | ©Wounds International 2012


trials and make informed purchase decisions. In 2008, a European and Japanese working party affiliated to the NPUAP Support Surface Standardization Initiative[3]


, began the process of


developing a controlled methodology for active surfaces. Phase 1, clinician consensus, has been published[20]


is under development. The concept phase is now complete and about to move into inter-lab validation.


CLINICAL PRESCRIPTION Active surfaces in general, and mattress replacements in particular, have proven cost- effective for the prevention[21]


and a standardised human analogue


and treatment[22,23]


of pressure injury, although a continued lack of well-designed comparative studies complicates the selection of a specific device from the wide range available[2]


. There are few restrictions on


the use of active surfaces, aside from unstable fractures, particularly of the spine. However, a small number of patients, such as those with intractable pain or severe muscle spasm, may find that the air cell movement exacerbates their condition. Active surfaces, by the very nature of their


design, periodically off-load the tissue, meaning that they are considered the modality of choice for patients who cannot be regularly repositioned[1]


. Examples might be end-of-life


care, intensive care, long-term care where reduced sleep interruption is preferred, or simply patient choice. Active cushions might be particularly useful for patients with existing wounds, such as patients with spinal injuries[24]


, as some studies


have shown ischial dermal perfusion to be similar to, or better than, that achieved by short duration ‘push-ups’[16]


and ‘forward-lean’ techniques[25] That said, active surfaces, whether for bed


or chair, are not designed to replace patient repositioning, but simply to complement a well- designed, holistic plan of care designed to reduce the risk of harm from prolonged pressure.


ACKNOWLEDGEMENTS The authors would like to thank ArjoHuntleigh for supplying the graphics used in this piece.


DECLARATION OF INTEREST ArjoHuntleigh has provided an unrestricted grant to support work of the Active Surface Standards Group, including author compensation for meeting attendance and laboratory studies.


AUTHOR DETAILS Lyn Phillips, BSc, RN, Dip N, Dip Research, Independent Clinical Consultant


.


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