PRODUCTS FOR PRACTICE Skin IQ TM Microclimate Manager made easy Volume 2 Issue 2 May 2011 www.woundsinternational.com Introduction This article describes the importance of microclimate control in pressure ulcer prevention and treatment. It focuses on the structure and mode of action of a new cover system the Skin IQ TM Microclimate Manager (KCI). For many years, the use of support surfaces in pressure ulcer prevention has concentrated on reducing the mechanical load on the skin. However, when selecting products, there is now a need for clinicians to also consider how well a support surface manages conditions at the interface between the skin and the support surface (the microclimate). Authors: Clark M, Black J. Full author details are on page 6. What is a microclimate? In relation to pressure ulcer development, microclimate was initially a term used to describe three aspects of the interface between the skin and a support surface skin temperature, humidity and air movement 1. In early pressure ulcer publications, the maintenance of a favourable microclimate was seen to be a key modifier of the ability of skin and underlying soft tissue to withstand prolonged stress (eg pressure and shear). However, the concept has been largely overlooked since the 1970s 2. Box 1 What is microclimate? (adapted from 2,4 ) Skin surface or tissue temperature Microclimate = or { Humidity and/or skin surface moisture Skin surface temperature can be measured at the skin/support surface interface with the patient still in contact with the surface or after moving out of contact with the surface Relative humidity (often abbreviated to humidity) relates the amount of water vapour in the air at a specific air temperature to the maximum amount of water vapour that body of air would hold at that temperature. Relative humidity can be measured using a hygrometer 5,6. Methods that examine the ability of skin to conduct electricity can measure the water content of the stratum corneum 7. In clinical practice, assessment of skin moisture may be more subjective, eg by using the moisture subscale of the Braden scale 8 Why is microclimate important? Successful pressure ulcer prevention depends upon a complex balance between two sets of parameters the external loads applied to the skin and soft tissues, and the intrinsic ability of the skin and soft tissues to withstand prolonged or excessive loading. If loading increases, and/or the intrinsic resilience of the skin and soft tissues deteriorates, the balance is tipped and pressure damage is more likely to occur (Figure 1). This concept is also illustrated in Figure 2. This is a modification of the Reswick-Rogers curve that describes the relationship between pressure and time 4. The area above the blue line indicates pressure and the duration of application that is likely to induce pressure damage. When the resilience of skin and soft tissue is compromised, however, the curve shifts to the left and down (the red line), demonstrating that in these cases lower pressure of a shorter duration can also cause damage. In recent years, microclimate has again been attracting attention, but is now associated with two parameters temperature (of the skin or the soft tissues) and humidity or skin surface moisture at the interface between the skin and the support surface 3,4. Air movement has been omitted from the more recent definition as the movement of air can itself affect skin temperature and local humidity or moisture. Further clarification of the elements of microclimate is needed to aid clinicians in judging the condition of patients who are using support surfaces 2. Objective measurement of skin temperature and humidity presents practical problems and may require equipment not readily available in clinical settings. Box 1 outlines recently proposed definitions of microclimate, with suggestions for measurement of the parameters involved. Figure 1 Pressure damage and the balance between intrinsic and extrinsic factors No pressure damage the skin and tissues are able to withstand the external loads Pressure damage when loads increase and/or the ability of the skin to withstand them decreases, the balance changes (from left to right below) so that damage is more likely to occur Damage No Damage Damage No Damage Damage No Damage Extrinsic: loading on tissues (pressure/shear/ friction) Intrinsic: resilience of the skin and soft tissues (tissue tolerance) 1
PRODUCTS FOR PRACTICE Skin IQ TM Microclimate Manager made easy As explained below, changes in the microclimate at the skin/support surface interface can affect the body s ability to withstand the effects of external factors, such as pressure. As a result, changes to microclimate may alter tissue tolerance and make pressure ulcers more or less likely to develop, depending on the temperature and humidity changes that have occurred. Focus on temperature Raised skin temperature may be related to pressure ulceration as higher temperatures increases metabolic demand, which raises the tissue s susceptibility to the ischaemic effects of pressure and shear (Figure 3). As body temperature rises, tissue demand for oxygen and energy also increases. It has been estimated that a 1 o C increase in body temperature increases metabolic demand by approximately 10% 9. Where skin, subcutaneous tissue and muscle perfusion are already compromised, any increased metabolic activity may give rise to ischaemia and subsequent tissue damage faster and at lower levels of pressure/shear than if the body temperature was normal 10. While the rise in metabolic activity results from increased body temperature, it has been suggested that elevations in skin temperature may also lead to skin and soft tissue damage, perhaps through weakening of the epidermis 2. In addition, raised body/skin temperature often induces sweating, which as explained below, may further increase risk of pressure damage. Focus on humidity Excessive moisture Excessive moisture on the skin s surface is believed to elevate the risk of pressure ulcer development by weakening the skin. Moisture weakens the linkages between the collagen fibres in the dermis and also softens the stratum corneum 11. As a result, excessive skin moisture and high relative humidity may mean that the skin can become boggy or even macerated. This will reduce the skin s smoothness, thereby raising the friction coefficient and increasing the likelihood of damage from shear and friction 2 (Figure 3). Causes of excessive moisture In hospital it is common for clinicians to turn patients and find that the skin and bed linen are damp. This sweat is produced in an attempt to cool the back, buttocks and legs due to the heat that accumulates where the body is in contact with the support surface. Excessive skin moisture can arise from a wide variety of causes. Patients at particular risk include those who are incontinent, febrile, have major injuries to the central nervous system, are in sympathetic nervous system overload, or who are extremely obese and have skin folds that are difficult to keep dry. Febrile patients perspire to cool the body. If these patients can be regularly repositioned, or move themselves, while in bed, excessive moisture may not become a problem. However, if the patient is immobile, the skin in contact with the bed may become very wet. Patients with central nervous system injuries may experience over activity of the sympathetic nervous system. The sympathetic nervous system is responsible for the fight or flight response and the reflexes involved induce excessive sweating. Patients in critical care units may also experience sympathetic nervous system overstimulation, as do dyspnoeic patients who sweat profusely in response to the stress of finding it difficult to breathe. Extremely obese (bariatric) patients often sweat profusely as the body attempts to control temperature. When these patients fill the width of a bed, turning or moving becomes very difficult and moisture may build up. Figure 2 Adaptation of the Reswick-Rogers curve to show the effect of reduced tissue tolerance (adapted from 4 ) Pressure Key Pressure ulcers develop Time Above the line, the magnitude and duration of pressure is likely to cause pressure damage. Below the line, pressure damage is unlikely to occur Pressure-time curve shifts to left and down when skin and tissue tolerance is reduced, lowering the pressures and durations required to induce pressure damage Excessive dryness Excessive dryness of the skin also causes challenges for tissue integrity. Dry skin has reduced lipid levels, water content, tensile strength, flexibility, and junctional integrity between the dermis and the epidermis 2. Dry skin is therefore weakened and more vulnerable to damage by pressure, shear and friction (Figure 3). Microclimate management in pressure ulcer prevention would, therefore, appear to necessitate avoidance of raised skin temperature (or even a slight reduction in skin temperature) and maintenance of levels of moisture or humidity that avoid excess wetness or drying of the skin. Microclimate management The initial approach to the management of extremes of microclimate should involve addressing the cause of excess temperature or altered skin moisture, eg by treating pyrexia or managing incontinence effectively 2. Fans may help 2
to cool the skin and will evaporate excess moisture. Patients who are dyspnoeic may find the air movement produced by a fan provides a sense of improved breathing 12. Additional approaches to managing the accumulation of excessive heat and moisture on the skin include encouraging the patient to move in the bed or through turning regimens. Movement will allow moisture to evaporate from areas previously in contact with the support surface. Control of skin moisture may be assisted by regular changing of gowns and bed linen. Bariatric patients in particular may benefit from frequent washing and changing of clothes. Incontinent patients require particularly careful management of the skin, which needs to be protected from future exposure to urine and faeces with products that repel these fluids. Where skin is dry, the use of emollients may be helpful 4. Recently, the application of large absorbent dressings to the sacrum in patients at high risk of pressure ulcers has been found to reduce pressure ulcer occurrence 13. This may be because of the absorption of skin moisture. However, it should be noted that the dressings also reduced pressure and that the study included an aggressive patient-turning schedule. Support surfaces and microclimate management Many of the mattress covers and support systems in use today are designed to reduce cross-contamination between serial users and are fluid resistant and easy to wipe down. Such surfaces may contribute to the accumulation of heat and moisture at the patient/support surface interface. Low air loss (LAL) overlays/mattresses and air-fluidised support surfaces both act in ways that may draw moisture and heat away from patients. LAL systems blow air into a series of inflatable cylindrical cushions that support the patient. The cushions allow air to escape through small pores and to flow along the inside of a vapour permeable cover. This draws moisture and heat through the cover into the air in the surface and away from the skin. Air can penetrate the cover in the reverse direction, out of the mattress and over the skin. Air-fluidised support surfaces pump air out through small holes in the support surface cover that also let fluids (eg sweat and urine) pass through. The temperature of the air can also be controlled. However, one issue with both LAL and air-fluidised support surfaces is that, by default, patients may block the holes of the covers as they lie on them. Figure 3 Microclimate and the risk of pressure damage Humidity/skin moisture Sweating pyrexia/critical illness/ obesity/sympathetic nervous system stimulation/dyspnoea Incontinence High environmental humidity Dry skin Weakened skin Coefficient of friction of skin Risk of pressure damage Metabolic demand Pyrexia Sympathetic nervous system stimlulation (critical illness/cns injuries/dyspnoea) Ischaemia Vulnerability of skin and soft tissues to the effects of pressure, shear and friction A new cover system, the Skin IQ TM Microclimate Manager, is designed to overcome this issue and assist with the management of microclimate to prevent pressure ulcers when used in conjunction with a pressure redistribution surface. Little information is currently available to clearly guide choice of a surface for the management of microclimate 2. The choice of a support surface will be guided by clinical judgement and numerous other factors (Box 2). What is the Skin IQ TM Microclimate Manager? The Skin IQ TM Microclimate Manager (Skin IQ TM MCM) is a mattress cover system designed to aid in the management of the microclimate of the skin when fitted over a pressure redistribution surface (Figure 4). The Skin IQ TM MCM has three layers (Figure 5): n a woven nylon fabric top layer that is vapour permeable but fluid-resistant and coated with an antimicrobial treatment. The cover helps to reduce shear and friction, and acts as a bacterial and viral barrier 3
PRODUCTS FOR PRACTICE Box 2 Factors influencing choice of surface for management of microclimate 2 n Requirement for pressure redistribution n Patient size n Patient mobility n Body temperature n Incontinence n Ease of use n Availability n Cost and reimbursement Figure 5 Structure of the Skin IQ TM MCM Top layer: fluid-resistant vapour permeable layer Middle layer: foam layer n a middle layer of open cells allows air to pass through the Skin IQ TM MCM, without the layers collapsing n a non-woven fluid-resistant vapour permeable bottom layer that is intended to prevent movement of the Skin IQ TM MCM over the top surface of the underlying pressure redistribution mattress. A small negative airflow device attached to the foot end of the Skin IQ TM MCM pulls air through the foam layer. How does the Skin IQ TM MCM work? The objective of the Skin IQ TM MCM is to help reduce or maintain skin temperature while preventing excess moisture or humidity building up on the skin s surface. The Skin IQ TM MCM is similar in some respects to a LAL therapy mattress/ Figure 4 The Skin IQ TM MCM system in situ overlay. However, it does not blow warm air into the surface, but in contrast uses a fan that pulls moisture and heat away from the patient (negative airflow technology) (Figure 6). The pump pulls room temperature air and moisture vapour through the outer layer and into the foam spacer layer towards the foot of the bed. Air entry sites are located at the head of the bed, but air and water vapour can also enter the cover system via the vapour permeable cover. The negative airflow provided also means that moisture and air are pulled away from areas where the skin is directly in contact with the support surface, meaning that the system may be better able than LAL and air-fluidised systems to manage skin moisture levels. Figure 6 Mode of action of the Skin IQ TM MCM Moisture Air Water vapour Bottom layer: fluid-resistant vapour permeable layer The moisture vapour transfer rate (MVTR) of the Skin IQ TM MCM top layer is reported to be 130g/m 2 /hr 14, which is higher than the rate measured for LAL surfaces (average MVTR 97.7g/m 2 /hr) 15. The MVTR measures the breathability of a material in terms of how well moisture vapour will pass through the cover material. A cover with a low MVTR allows moisture to quickly build up on the skin s surface. Pressure redistribution is provided by the underlying mattress with the additional benefits of negative airflow technology provided by the Skin IQ TM MCM skin surface cooling, prevention of excessive moisture, and reduced friction. What are the special features of the Skin IQ TM MCM? The Skin IQ TM MCM allows clinicians to Mattress Negative airflow device Airflow entry (head of bed) Airflow exit (foot of bed) 4
Figure 7 The system connects to the power supply and can be plugged in or disconnected In an earlier study, Lachenbruch has argued that a 5 o C reduction in skin/ support surface interface temperature would confer tissue-protective effects similar in magnitude to the interface pressure reductions afforded by the most expensive support surfaces 17. This hypothesis remains untested. manage skin temperature and moisture/ humidity while using existing pressure redistributing mattresses. The Skin IQ TM MCM can be stored in a nursing unit, allowing immediate application to a bed when indicated. The Skin IQ TM MCM can be applied without needing to move the patient from the bed. Its low height (6.35mm) only slightly increases the total height of the support surface, and so does not significantly affect ease of patient transfer from bed to standing, or the probability of falls from the bed. The single patient, 30-day use of each Skin IQ TM MCM is designed to prevent crosscontamination between successive patients. Bench studies have shown that negative airflow technology reduced Staphylococcus aureus growth by 2.24 logs over a 24-hour period when compared to a hospital bed sheet. They have also shown that negative airflow technology significantly reduced odour at the patient/surface interface when compared to the same surface without airflow 14. The product acts as a bacterial and viral barrier (like human skin), plus the three components top layer, interface layer and bottom layer are all coated with a bactericidal treatment. The reduction of temperature and moisture on the skin also reduces the potential for bacterial growth. What is the evidence supporting use of the Skin IQ TM MCM? Following the recent introduction of the Skin IQ TM MCM, work is now underway to gather a body of clinical evidence of its effect in reducing pressure ulcer incidence. There is a small body of indirect evidence supporting control of local microclimate in pressure ulcer prevention. This was reviewed in the international consensus document on pressure, shear, friction and microclimate 2. In an animal study, pressure of 100mmHg was applied for five hours with indentors heated to 25, 35, 40 or 45 o C 16. Cutaneous and deep tissue damage was observed at 40 o C and 45 o C, with moderate muscle damage seen at 35 o C. No cutaneous or muscle damage was observed where a load was applied at 25 o C, suggesting that local cooling may have a protective effect. Clark reported that the humidity above the sacral skin of elderly hospital patients who subsequently developed Category II pressure ulcers was higher than the humidity above the sacrum of patients who did not 5. While there may be few direct studies that implicate either changes in temperature or humidity as predisposing factors in pressure ulcer development, clinical judgment has long associated microclimate changes with increasing vulnerability to pressure ulcers in the presence of pressure and shear 4. When should the Skin IQ TM MCM be used? The Skin IQ TM MCM is intended for use in all care settings in the care of individuals who are perceived to be at risk of pressure ulcer development, who have been allocated a pressure redistributing mattress, and whose pressure ulcer vulnerability includes either prolonged exposure to moisture or high skin temperatures, eg patients who are incontinent or febrile 18. It is also intended for overall pressure ulcer prevention and patient comfort. How should the Skin IQ TM MCM be used? The Skin IQ TM MCM is intended for single patient use only. It should not be used for longer than 30 days and should be disposed of following the manufacturer s instructions after patient use 18. 5
The complete Skin IQ TM MCM package incorporates the cover system, a power supply and a power cord to connect to an electrical supply (Figure 7). The cover system and power unit can also be obtained separately. While the cover system and negative airflow device are only to be used in the care of a single patient for 30 days, the power supply and cord can be reused and should be cleaned in accordance with local guidelines on the cleaning of electrical units between patients. Contraindications and precautions The Skin IQ TM MCM should not be used in the care of people with an unstable spinal cord injury and those undergoing cervical traction. The Skin IQ TM MCM is designed to fit pressure redistribution surfaces that are 2.03 2.13m (80 84 inches) long and 88.9 91.44cm (35 36 inches) wide. It may be used in the care of people weighing up to 227kg (500lb) 18. However, clinicians should check that the pressure redistributing mattress and bed frame can support these weights before use. The Skin IQ TM MCM may have different surface characteristics (ie reduced friction between the patient and the pressure redistributing mattress). When should use of the Skin IQ TM MCM be discontinued? Use of the Skin IQ TM MCM should stop and the coverlet be replaced at the end of the 30-day warranty period. Skin IQ is also recommended for its comfort, meaning that patients can benefit even if microclimate is no longer the issue. Useful links Definitions of the different support surfaces used in the prevention and treatment of pressure ulcers can be found at: http://www. npuap.org/npuap_s3i_td.pdf References 1. Roaf R. The causation and prevention of bed sores. J Tissue Viability 2006; 16(2): 6 8. 2. International review. Pressure ulcer prevention: pressure, shear, friction and microclimate in context. A consensus document. London: Wounds International, 2010. Available at: www.woundsinternational.com 3. National Pressure Ulcer Advisory Panel (NPUAP). Support Surface Standards Initiative. NPUAP, 2007. Available at: http://www.npuap.org/npuap_s3i_ TD.pdf 4. NPUAP and European Pressure Ulcer Advisory Panel (EPUAP). Prevention and Treatment of Pressure Ulcers: clinical practice guideline. 2009; NPUAP; Washington DC, USA. 5. Clark M. The aetiology of superficial sacral pressure sores. In: Leaper D, Cherry G, Dealey C, Lawrence J, Turner T (eds). Proceedings of the 6th European Conference on Advances in Wound Management. 1996; McMillan Press, Amsterdam: 167-70. 6. Schäfer P, Bewick-Sonntag C, Capri MG, Berardesca E. Physiological changes in skin barrier function in relation to occlusion level, exposure time and climatic conditions. Skin Pharmacol Appl Skin Physiol 2002; 15: 7 19. 7. Egawa M, Oguri M, Kuwahara T, Takahashi M. Effect of exposure of human skin to a dry envirnoment. Skin Res Technol 2002; 8(4): 212 18. 8. Bergstrom N, Braden B, Laguzza A, Holman V. The Braden scale for predicting pressure sore risk. Nurs Res 1987; 36(4): 205 10. 9. Fisher SV, Szymke TE, Apte SY, Kosiak M. Wheelchair cushion effect on skin temperature. Arch Phys Med Rehabil 1978; 59(2): 68 72. 10. Brienza DM, Geyer MJ. Using support surfaces to manage tissue integrity. Adv Skin Wound Care 2005; 18: 151 57. 11. Mayoritz HN, Sims N. Biophysical effects of water and synthetic urine on skin. Adv Skin Wound Care 2001; 14(6): 302 8. 12. Galbraith S, Fagan P, Perkins P, Lynch A, Booth S. Does the use of a handheld fan improve chronic dyspnea? A randomized, controlled, crossover trial. J Pain Symptom Manage 2010; 39(5): 831 38. 13. Brindle CT. Outliers to the Braden Scale: Identifying high risk ICU patients and the results of prophylactic dressing use. World Council of Enterostomal Therapists J 2009; 30(1): 11 18. 14. Data on file please contact KCI for further details. 15. Reger SI, Adams TC, Maklebust JA, Sahgai V. Validation test for climate control on air-loss supports. Arch Phys Med Rehabil 2001; 82(5): 597 603. 16. Kokate JY, Leland KJ, Held AM, et al. Temperaturemodulated pressure ulcers: a porcine model. Arch Phys Med Rehabil 1995; 76(7): 666 73. 17. Lachenbruch C. Skin cooling surfaces: estimating the importance of limiting skin temperature. Ostomy Wound Manage 2005; 51(2): 70 79. 18. KCI Skin IQTM Microclimate Manager. Instructions for use. 2010; Data on file please contact KCI for further details. Supported by an educational grant from KCI. The views expressed in this Made Easy section do not necessarily reflect those of KCI. Author details Clark M 1, Black J 2. 1. Independent Consultant, Cardiff, UK. 2. Associate Professor, University of Nebraska Medical Center, College of Nursing, Omaha, Nebraska, USA USA disclaimer Skin IQ tm Microclimate Manager units have specific indications, contraindications, safety information and instructions for use. Please consult product labelling and instructions before use. For instructions, compatibility, and safety information specific to the bed mattress/ frame, please consult product labelling provided by the manufacturer. CAUTION: Federal law restricts the device to sale by or on the order of a physician. Summary Further research is needed to fully define the optimal skin support surface microclimate, but existing evidence indicates that preventing accumulation of excess moisture and increases in skin temperature have a role to play in preventing pressure damage. The Skin IQ TM MCM is a new type of cover system that enables management of microclimate even where the skin is touching the support surface by drawing away moisture and heat. The system is easy to apply to beds, does not affect the pressure redistributing characteristics of the underlying surface, and does not significantly add to support surface height. To cite this publication Clark M, Black J Skin IQTM Microclimate Made Easy. Wounds International 2011; 2(2). Available from http://www.woundsinternational.com DSL#11-0152.US (4/11) Wounds International 2011 6