Cath Lab Digest

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Index: Ostomy Wound Manage. 2008;54(10):26-35.

Abstract

  Severe pressure ulcers and deep tissue injury are associated with higher mortality rates, longer hospital stays, and costly treatment. Time is a critical factor in commonly employed measures (eg, pressure redistribution for wheelchair users and patient turning schedules) to prevent pressure ulcers and deep tissue injury. Surprisingly, information regarding the timeframe for pressure ulcer onset, particularly for deep tissue injury onset, is scant. To create a timeframe for the development of pressure ulcers and deep tissue injury, available evidence from the following study types was obtained and reviewed: 1) studies involving patients who underwent surgeries of known duration and subsequently developed a serious pressure ulcer with subcutaneous tissue damage or deep tissue injury; 2) animal studies in which loads were applied on soft tissues of anesthetized animals and tissue viability monitored in real time or using histology post-euthanasia; and 3) in vitro models in cell cultures and tissue-engineered constructs. Findings from the three models indicate that pressure ulcers in subdermal tissues under bony prominences very likely occur between the first hour and 4 to 6 hours after sustained loading. However, research examining these timeframes in sitting patients is not available. Further fundamental research, employing animal and cell culture models, is required to narrow this range further and to correlate the time factor to the extent of tissue damage.

KEYWORDS: pressure ulcer, deep tissue injury, animal model, tissue engineering, injury threshold

   Although time is a critical factor in measures taken (eg, pressure redistribution for wheelchair users and patient turning schedules) to minimize the incidence of pressure ulcers (PU), information in the literature is far from definitive. According to current prevention guidelines from the European Pressure Ulcer Advisory Panel (EPUAP) (www.epuap.org), “individuals who are able should be taught to redistribute weight every 15 minutes,” but this is qualified by a note that this recommendation is based on expert opinion and few clinical observations. This is just one example of the overall paucity of data on times that are safe/unsafe relevant to positioning. Information is scant regarding the timeline for PU onset and particularly for onset of deep tissue injury (DTI), a condition that places patients at high risk for sepsis, renal failure, and organ system failure.

   To create a timeframe for the onset of PUs, a literature review was conducted of available published data involving time to subdermal tissue damage and particularly DTI because it has been reported that pressure-related damage occurs sooner and faster in muscle tissue than in fat and skin.^1,2 Indeed, the US National Pressure Ulcer Advisory Panel (NPUAP) added a new PU category in 2007 – “suspected DTI” — to adopt these changes.