Cath Lab Digest

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Because the skin covers such a large area and receives only capillary blood flow, many factors affect the skin’s and its supporting structures’ ability to remain intact, including factors that affect tissue perfusion such as hemoglobin levels, interstitial and lymphatic flow, oxygen supply and demand, and the presence of endotoxins.¹¹

  Langemo and Brown¹² conducted a systematic review of terms associated with acute, chronic, and end-stage skin failure. They defined acute skin failure as “an event in which skin and underlying tissue die due to hypoperfusion concurrent with a critical illness.” They noted that when patients become critically ill, they develop risk factors for PUs as well as skin failure, such as poor tissue perfusion, decreased nitrogen balance, and immobility. Critically ill patients with multi-organ failure/dysfunction and sepsis are especially at risk for hypoperfusion due to microvascular dysfunction, increased oxygen demand, and vasoconstriction. This phenomenon has been noted by Reger et al¹³ in an analysis of support surface interface pressure, Lamblin et al¹⁴ in a study of 10 sedated ICU patients, and Campbell et al¹⁵ in a review article on the metabolic response to trauma and sepsis.

  Compromised skin integrity may be closely associated with mortality. A nonexperimental, retrospective analysis16 of PU data involving 74 patients showed that patients who develop full-thickness PUs had a 180-day mortality rate of 68.9%, and the deaths were unrelated to the PUs — ie, the development of a full-thickness PU was a precursor, not a cause, of death.

  Many patients in the ICU are mechanically ventilated and require sedation. A recent prospective observational study¹⁴ of 10 patients demonstrated that medications used to sedate ICU patients also cause changes in microcirculation and postulated this also may alter tissue perfusion. Critically ill patients also frequently develop symptoms of poor nutrition such as loss of lean tissue and reduced body mass; a review of the literature¹⁵ on nutritional support of patients experiencing multiple organ failure found that patients with multi-organ failure/dysfunction, sepsis, or systemic inflammatory response syndrome are especially at risk for malnutrition due to alterations in metabolism and absorption.¹⁵

  In 2008, a panel of experts¹⁷ developed a consensus statement on the concept of skin changes at life’s end (SCALE). The panel included a number of wound care experts and developed several position statements to enhance understanding and management of the physiologic changes affecting the skin and soft tissue as a result of the dying process. These changes can result in a specific type of skin ulcer known as a Kennedy Terminal Ulcer (KTU). The panel noted that not all conditions typically described as PUs are preventable. Similarly, as Yastrub¹⁶ describes in her viewpoint paper defining terminal ulcers, many clinicians mistake a KTU for a PU. However, KTUs are hypothesized to be caused by a shunting of blood away from the skin to other organs during the process of dying.¹⁸ The author further noted times during which skin damage is unavoidable. It is evident that some forms of skin failure are not well understood, and further research into the various causes of skin failure is needed. Table 1 presents definitions developed and adopted for the current study based on a compilation and analysis of sources in the literature.

Other Common ICU Complications

  Sepsis can induce MODS and can be an independent complication of a patient’s stay in the ICU.