Skin Failure: Concept Review and Proposed Model

Abstract

Skin failure is increasingly recognized as a clinical syndrome. Like all other organs, skin can fail; however, experts continue to grapple with definitions, causative factors, and identifying manifestations.1,2 There are currently a number of overlapping clinical entities that have not been well defined by rigorous research criteria nor recognized by all providers and regulatory bodies across the healthcare continuum.1 Establishing skin failure as an entity by defining contributing factors similar to other organ systems will enable providers to recognize and address it effectively in practice and assist regulators by recognizing and incorporating these pathophysiologic factors into quality measurement criteria.2 There is a pressing need to define skin failure as a clinical syndrome and understand its pathophysiology because of its implications for both clinical care and healthcare policy. For over 3 decades, clinicians have sought clarity on skin failure, offering various hypotheses and nomenclatures regarding its genesis and existence. The purpose of this article is to establish a scientific basis for skin failure by identifying pathophysiologic factors that lead to consequences at the cellular level resulting in disruption of the cutaneous barrier and underlying tissues. The model in the Figure details the synergy of these factors including acute and chronic conditions and how they act to alter dermal physiology leading to barrier disruption and skin failure. The model does not include wounds related to acute trauma such as lacerations or skin tears, wounds related to malignancy, or factors that impact healing discussed elsewhere.3 Rather, the goal of this article is to propose a conceptual framework for future discussions and research as well as a path to a clear, unifying classification system that takes into consideration terminologies and diagnoses that fall within the skin failure spectrum.Figure: RISK FACTORS AND PATHOPHYSIOLOGIC CHANGES RESULTING IN DERMAL BARRIER DISRUPTION AND SKIN FAILUREIt should be noted that current definitions of skin failure assume visible changes and/or disruption of the dermal barrier. However, the physiologic processes that lead to skin failure take place before visible disruption appears and may involve tissues below the skin, including connective tissue and muscle, which are subject to the same stressors. SKIN FAILURE: CONCEPTS AND CONTROVERSIES A definition for skin failure was initially proposed by Irvine4 in 1991: “Skin failure could be defined as a loss of normal temperature control with inability to maintain the core temperature, failure to prevent percutaneous loss of fluid, electrolytes and protein with resulting imbalance and failure of the mechanical barrier to penetration by foreign materials.”4 He proposed that skin failure is equivalent to the failure of other organs and included etiologies such as thermal burns and dermatologic conditions such as erythroderma, toxic epidermal necrolysis, and Stevens-Johnson syndrome, but did not mention pressure injuries (PIs) as a manifestation of skin failure.4 The next contribution to the definition of skin failure was offered by Langemo and Brown5 in 2006: “…an event in which the skin and underlying tissue die due to hypoperfusion that occurs concurrent with severe dysfunction or failure of other organ systems.”5 They postulated the existence of acute skin failure occurring with critical illness, chronic skin failure concurrent with chronic disease states, and end-stage skin failure occurring at the end of life, with hypoperfusion as the primary cause.5 Langemo and Brown’s definition was expanded by Levine,2 who stated, “Skin failure is the state in which tissue tolerance is so compromised that cells can no longer survive in zones of physiological impairment that includes hypoxia, local mechanical stresses, impaired delivery of nutrients, and buildup of toxic metabolic byproducts.”2 He further acknowledged that skin failure could be acute or chronic, and chronic skin failure is characterized by disruptions in skin integrity that fail to heal or regenerate in a normal sequential manner to regain structure and function. Delmore et al6,7 furthered the acute skin care definition through their research. Like Langemo and Brown, Delmore and Cox stated that acute skin failure is a complex phenomenon distinct from a PI.5–7 They postulated that the main etiology is attributable to failure of the skin and/or supporting structures from diseases and conditions during critical illness.7 The dermatology literature offers a different set of criteria whereby acute skin failure is a life-threatening situation with single-organ genesis requiring immediate treatment.8–10 These diagnoses share a series of events that result in involvement of the entire body with consequences that include hemodynamic changes, impaired thermoregulatory control, and metabolic complications.8–10 Several authors have proposed a variety of terminologies and clinical syndromes that fall within the spectrum of skin failure. These include the Kennedy terminal ulcer, Trombley Brennan terminal tissue injury, Skin Failure at Life’s End, and unavoidable PI.1,11–13 In a review of terminal ulcer terminology, Levine14 pointed out these terms’ intrinsic weaknesses that include conflating separate concepts of diagnosis and prognosis, the wide spectrum of definitions of the end-of-life period, and the lack of accuracy in predicting death.14 Adding to the confusion, the term acute skin failure, which commonly occurs in critical care situations, is often used interchangeably with the more general term skin failure.15–17 The distinction between skin failure and PI remains controversial.6,15–20 In 2010, experts at a consensus conference hosted by the National Pressure Ulcer Advisory Panel defined unavoidable PI as occurring even though providers have evaluated the individual’s clinical condition and risk factors and implemented interventions that are consistent with individual needs, goals, and recognized standards of practice.21 Adding further complexity, the CMS adopted the concept of unavoidable PI and terminal ulcers in their regulations governing skilled nursing facilities, although there are no similar guidelines in acute care environments.22 This disparity is perplexing because human disease follows the same pathologic and physiologic principles across the healthcare continuum. In addition, PIs are a commonly designated quality indicator.23 A determination of quality deficit brings adverse consequences including dissatisfied patients, regulatory citations, and risk management issues, all of which may not be warranted if the quality indicator is faulty or inadequately defined or, in this case, inconsistently applied. When determining the presence of skin failure, the clinician’s focus should be on the primary etiology of a wound, whether it occurred from pressure forces or a combination of pathophysiologic factors leading to skin failure. Proper prevention strategies should always be applied based on a patient’s risk factors, and wounds occurring from inadequate prevention should not be labeled as skin failure or acute skin failure. When all possible strategies have been applied and a wound still evolves, the next step is to determine the primary etiology. Dermal Anatomy and Physiology Relevant to Skin Failure Before identifying and discussing the risk factors and physiologic consequences of skin failure, a brief review of dermal anatomy and physiology is necessary to provide context. The skin is the largest and arguably the most complex organ, and to this point, its multiple functions are summarized in Table 1 (not all of which pertain to the proposed model of skin failure). Table 1 - ORGAN FUNCTIONS OF SKIN Function Description Physical barrier This is localized primarily in the anucleated stratum corneum and nucleated epidermis, which contains tight cellular junctions and lipid-rich extracellular layers, keratin filaments, and macrofibrils Chemical barrier Maintains moisture and acid mantle of the promoting commensal bacteria and inhibiting pathogens Immunologic barrier Immunologic defenses composed of the cellular and humoral elements including Langerhans cells, B and T lymphocytes, complement system, antimicrobial peptides, and dendritic cells Microbiome barrier Skin is colonized by a variety of microorganisms that are either symbiotic (each organism benefits) or commensal (one organism benefits). These organisms have roles in the cutaneous immune system and inhibiting pathogens Thermoregulation The skin regulates body temperature with its blood supply. Dilated vessels allow for heat loss, whereas constricted vessels retain heat Osmoregulation The process of maintaining salt and water balance through sweat glands Endocrine function Vitamin D3 is produced in the skin, and sebaceous glands are important in testosterone metabolism. The skin is also rich in glucocorticoid, thyroid, and estrogen receptors BP maintenance Peripheral vascular resistance in the skin’s extensive arterioles and capillary beds has a dynamic role in cardiovascular dynamics by maintaining BP Sensory function Skin facilitates the perception of many sensations. Sensory receptors are divided into mechanoreceptors, thermoreceptors, nociceptors (pain sensation), and pruriceptors (itch sensation) Socialization and reproduction Social engagement starts at birth with skin-to-skin contact when the baby is made to feel part of a family. Skin tone as genetically manifested by melanocytes can determine ethnic or racial experience in life. As an external organ, skin sends signals of physical attractiveness that are often critical in human reproduction Adapted from Levine.31 The discussion on skin failure concentrates primarily on physical, chemical, immunologic, and microbiome barrier functions, all of which intertwine to protect the organism.24–26 The physical barrier is composed of various anatomic levels of skin that include the system of tight junctions between cells in the stratum corneum and the complex vascular structures that supply oxygen and nutrients and remove waste. The immune barrier is composed of resident cells that sense microbial danger signals, initiate immune response, and trigger inflammation. The chemical barrier is composed of sebum, which contains triglycerides and cholesterols, as well as an acidic surface pH, all of which maintain natural moisturization. The microbiome barrier is a microbial community including commensal bacteria and fungi that control potential pathogens. Underlying illnesses and concomitant physiologic aberrancies weaken barrier function and can result in skin failure. Despite its and complexity, and in with other organ there are currently no to skin failure. In failure can be by presence of and failure can be with blood and failure can be with and The of should not prevent clinicians from skin failure if clinical criteria are defined and There is an need to recognize the existence of skin failure, define clinical and in Anatomy and that the diagnosis of skin failure is not possible when are to of the organ in dermatologic conditions such as Stevens-Johnson syndrome or toxic epidermal A of this is the that skin failure and PIs are separate These not when into consideration in skin anatomy and physiology and how these alter the to in the of and/or There are anatomic in epidermal of and of presence of muscle, structure of dermal of presence of of and other vascular and These are genetically in that during and in a level of anatomic and physiologic is in of skin commonly in are also by and the to local of skin In addition, and other such as can alter and anatomy and physiology of skin, as well as disease processes that and The and are in their and structure with the of the more to skin failure in the presence of multiple and chronic The and in and tissue these the is more compromised the and and allow tissue and skin has capillary but This imbalance can tissue and when are that tissue and the and will be The the same and is to The is a with skin and tissue that its blood from The body has been as a by for of skin and underlying with When a disease process such as a the of skin by that will be more to failure When such as disease are the of these to hypoperfusion is further of tissue in the of multiple physiologic will the process of local skin failure. Skin There are pathophysiologic factors that to the that skin failure and acute skin failure are the result of multiple acute and These include hypoxia, vascular and Skin failure may include levels of tissue to and/or below the skin that share similar on nutrients, and skin failure can be as a local or is blood to an has multiple including of the and In or states, the to tissues and organs such as failure, and blood loss will the to maintain Failure of the cardiovascular system to tissue to dysfunction in cellular and impairment in both oxygen and failure can result in hypoperfusion when function is is a state of of the blood that to impaired tissue can tissue oxygen levels and is with is when oxygen to failure of When oxygen delivery is a physiologic occurs at the cellular level that includes cellular and by the to including of oxygen forces cells to from to resulting in a deficit of and cellular by leading to metabolic As blood in the blood In severe such as blood is from the to and to the organs, which in to skin including anatomic such as the impaired tissue the skin’s tolerance for pressure by to at and diseases to and are important risk when in a spectrum of vascular disease that includes and and resulting in local and tissue The of and has been to many conditions including and acute The can be acute or chronic and as a to trigger and initiate is it can tissue by the vascular and function of the dermal barrier and underlying In this and and delivery and the risk for skin failure. is by in tissue by conditions including and physical and chemical a of changes to that includes vascular into the and blood can as a result of an acute response, or as a distinct clinical process with and chronic illnesses including a of and are with levels of that to vascular as a result of dysfunction occurs with an of resulting in of into the of a of cells that a dynamic barrier between the blood and include the extracellular and that from into the of vascular is on of intrinsic and factors and and vascular is by BP and regulators such as factors and such as burns and the barrier. Several disease vascular include immune and as well as in The presence of these conditions the for vascular with a for skin failure because of impaired oxygen and and inability to remove waste. in an of either within cells or in the the for delivery of oxygen and other nutrients and There are of and is primarily a of whereas is by and impaired to the of PIs and tissue and its have multiple including pressure from vascular and as well as illnesses including failure, and that include and is a of from loss of pressure and has many contributing factors, including syndrome, failure, chronic or and level can in the of and is a the tissue delivery and and to skin In an of underlying pathophysiologic factors can lead to skin failure For with acute conditions can experience hypoxia, and in vascular which as Skin failure is a complex phenomenon of multiple conditions and cellular and A number of acute and chronic conditions physiologic that or disruption of the cutaneous barrier and underlying tissues. This how these lead to skin failure. The authors that there are complex conditions that may not fall into a physiologic classification leading to skin failure, including changes with and the organ dysfunction syndrome is the dysfunction of or more organs as a result of a by a severe or which can result from an process such as or conditions such as A of is of blood and state with inadequate oxygen delivery to the imbalance in the for oxygen and to body tissues and organs in cellular impaired cellular and risk for skin failure. of these are by syndrome and severe both of which and capillary As discussed by Langemo and skin as an organ is subject to failure. as the largest organ of the acute skin failure should be in the spectrum of Skin injuries with have been by acute skin failure in failure of organs and to be with the of acute skin In a Delmore et and failure of acute skin failure. the skin’s barrier function and and a role in both and from inadequate of and as well as or balance from and other This a as from and with of and condition that in and/or will the risk for and the to with and other a state whereby the skin to physiologic skin failure by all levels of the cutaneous barrier vascular immune and so the skin’s to to and to skin failure. The immune system is an of the dermal barrier for both prevention and There are multiple of the dermal immune system including and and humoral and maintenance of the When tissue or by the immune system in to prevent further and initiate the process of include antimicrobial and that in skin by The of human skin is it for pathogens and promoting a commensal and of cellular and humoral and tissue function and as by which are a of the skin’s immune system, are in Table Table - OF DERMAL OF SKIN cells cells and cells T Adapted from and of its complexity, immune system can multiple and in with other physiologic can lead to skin failure. can include diseases such as factors such as and changes with is a disease commonly with immune resulting from of and dysfunction leading to resistance to which further skin and multiple integrity of the cutaneous to skin failure. There are acute and chronic conditions that may not fall into a physiologic classification leading to skin failure, including changes with and the but that have a in the of For a discussion in is between changes with and changes with is an term that the to disease that occurs with because of physiologic This concept has been into the concept of which is with are both intrinsic and and both and physiologic that the of skin The result is and risk for which can the process of skin Table 3 - FUNCTIONS AND BARRIER Dermal Thermoregulation Sensory perception Vitamin Adapted from Levine.31 and are conditions with that share of and is characterized by and to to physiologic resulting in and risk for adverse is postulated that a that in and failure to and is with a and loss of and and many a of of include blood to muscle, and in such as of their impact on function and both and should be risk factors for skin failure. The barrier function of skin cellular structures and anatomic between A number of forces or disruption of the cutaneous barrier and underlying tissues. This of how and the function of skin leading to skin failure. This discussion regarding impairment does not include acute trauma such as and skin and are in systems that have the to and to their and external The barrier function of skin is on this This includes the to maintain the and and normal The for the mechanical to extracellular forces that can and The can with external forces tissue leading to and loss of a of that to as by pressure and is an important of PI the impact of external and the authors include PI as a that integrity and to skin failure. to the skin’s barrier function that include from to various of moisture or the failure to maintain However, moisture is not to skin but the chemical of the moisture and presence of microorganisms to impaired skin The by the chemical of the causative and of the acid mantle with changes in with the to bacteria and maintain normal in the of skin failure, and similar to external forces of and other moisture can failure of the skin’s barrier function. Several to skin failure through a variety of including of skin in blood and impaired immune function. also as are that have the immediate of the immune or can lead to of the In to immune and both of which can of are often in the of to blood from the skin and to vessels by vascular resistance and pressure in of their to the of PIs in critical The risk may be by of more and mechanical contribution to acute skin failure is but this and further is cells at different in the resulting in impaired but adverse events skin are well of from cellular to cutaneous As a result of these on various cells and in with the of and other can risk for skin and are a of that the of and diseases and assist in the of of but they share of various of the immune have adverse on wound healing and the risk for the immune system is a of the cutaneous immune could the risk for skin failure in with other For both and it is the of both the condition and the that the skin to The Skin disruption in who are was recognized in the when the The process is with in skin and a variety of terminologies have been offered to terminal In healthcare of this is because there is no consensus as to the end-of-life offers interventions to or the these in who are recognized by both clinicians and as on skin changes with the process is however, commonly recognized physiologic changes include and oxygen In an to define skin failure within this the proposed model a of physiologic principles to this clinical syndrome, which is recognized across the healthcare continuum. The model disruption of skin integrity related to the process as a of the spectrum of skin failure. and The dermatologic literature offers postulated to skin These include Stevens-Johnson syndrome, toxic epidermal necrolysis, and that are by hemodynamic changes, impaired thermoregulatory control, and metabolic of their organ genesis as proposed by the dermatologic they as a separate in the proposed conditions such as can the intrinsic structure of skin and underlying it to failure when to and external stressors. The of can for or on and these involve the epidermal and dermal layers, or other structures can be an to skin tissue contains and that of the of normal In addition, many PIs have in the and of wound resulting in intrinsic as this tissue is a potential for skin failure. Skin is the largest organ of the body and arguably the most as there is no function of skin, there is no of skin failure. a clinical the term skin failure not to skin but also to the levels of tissue and of the pathophysiology of skin failure has important implications for clinical quality and healthcare policy. In to skin failure, pathophysiologic that can be a this clinical This article a model that on physiologic principles to other organ systems that to across the healthcare continuum. is that future research will physiologic that are if not more important to in this such as When a wound, the the to determine the risk factors that and determine the most etiology. should include a that includes risk factors and underlying The term acute skin failure could be when causative factors are with acute critical should be that these should not be applied to wounds attributable to inadequate or prevention Proper prevention should always be applied based on a patient’s risk When all possible strategies have been including interventions and care and a wound still evolves, the next step is to determine the primary etiology. The proposed model for skin failure brings a variety of elements that include risk factors, pathophysiologic and overlapping entities that include terminal the on etiology and classification discussed and in the regulatory a path to further skin failure and acute skin failure and to further and supply a for and consistent The authors regarding of an of for skin failure or related on the skin failure spectrum such as terminal further is and consensus is A of skin failure could for and

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