Wound Care Information Network











Support Surface

The following information was furnished by Gaymar Industries, Inc. For more information on this topic, you may contact them at 800-828-7341.

Pressure ulcers may be a complication of immobility. The major cause of pressure ulcers is generally accepted to be an external pressure that occludes blood vessels.  Two mechanical forces that contribute to pressure ulcers are a combination of direct downward pressure and shear pressure.   Direct downward pressure, or tissue interface pressure (TIP), can occlude blood capillaries and cause ischemia to the area supplied by the affected vessels (figure 1).  

Prolonged ischemia leads to cell and tissue death.  Shear pressure is a horizontal force that occurs when the skin and underlying subcutaneous tissues are pulled taunt and over-stretched, causing tissue deformity, obstructing blood flow, and tissue necrosis (figure 2). 

Many investigators have measured the relative contribution of shear and pressure in causing the occlusion of blood flow.  It has been suggested that in the presence of shear, the amount of direct pressure required to occlude blood flow is reduced by a factor of 4.  

 Pressure and shear will be higher in areas where soft tissue lies over bony prominences (figure 3).  Since pressure and shear are major causes of pressure ulcers, it is paramount that these forces over bony prominences be reduced. *

Everyone is subject to the mechanical forces of pressure and shear.  In healthy individuals, the effects of pressure and shear are balanced by protective mechanisms that impact the body response to those forces.  The ability to move and be active may be impaired in certain populations, due to underlying medical conditions.  With any degree of immobility, the protective mechanisms are less effective in balancing out the detrimental effects of pressure and shear.     

Various strategies exist to manage the effects of pressure and shear in individuals who have impaired mobility.  A plan of care is developed to compensate for the inherent disability.  Initially, patient education includes the importance of frequent turning and repositioning.  If a person is not able to move him or herself, the caregiver is charged with the task of moving the patient/resident.  Turning and repositioning is the single most effective way to compensate for impaired mobility.  Unfortunately, turning and repositioning a patient every two hours may not be enough to prevent the development of a pressure ulcer.  It may not be in the best interests of the patient to be moved on a recommended schedule.  Another strategy is to use a special support surface to assist in the management of pressure and shear force.

The search for the perfect support surface will prove fruitless because support surfaces are but one facet of a total approach to pressure ulcer prevention.  To be complete, the plan of care will integrate support surfaces as an integral part of the approach to total care management of pressure ulcers. *

Evaluation of support surfaces for clinical use has been a source of frustration in the recent past. The healthcare community is challenged to establish standards; criteria for evaluation that are evidence based.  Randomized, prospective, controlled clinical trials have been the gold standard, but they are an unrealistic approach due to cost.  Tissue interface pressure measurement is another approach to evaluation.  Incorporating shear force into the equation is yet another approach.  Today, support surfaces may be evaluated in terms of their performance.  The features and benefits that support surfaces provide effect the way they can meet patient needs.  Clinical application of support surfaces begins with a methodological approach to selection of the appropriate support surface. *

An important part of the prevention and treatment of pressure ulcers is placing people on an appropriate support surface.  Choosing the appropriate support surface is not an easy task as there is no standard criteria to evaluate support surfaces. Therefore, it is important to assess the performance of each type of support surface accurately, identify individual patient needs and then select the most appropriate option based on a well-informed, educated approach.

Over the past three decades hundreds of support surfaces have been developed.  Support surfaces used for the prevention and treatment of pressure ulcers may be classified according to their physical form and function. *  The three physical forms are:

  1.  mattress overlay

  2.  mattress replacement

  3. full-framed specialty bed. 

Each form may take on special functions and offer features and benefits for the prevention and treatment of pressure ulcers in targeted groups of individuals.  These functions may include:

  • static

  • alternating/pulsating

  • low air loss

  •  immersion (air fluidized, water, gel)

  •  turning/rotating/oscillating

1.  Mattress overlay is a general term to describe a support surface that is placed on top of a mattress.  Overlays may be constructed of foam, air, or gel.  Depending upon the primary component, the overlay may then function as static, alternating, low air loss or immersion.  Assessment of patient needs is matched to the performance of the support surface.  Patient assessment indicates the function and features that a support surface must perform to meet the identified needs of the patient.     

Static air overlay 

Alternating air overlay

2.  Mattress replacement for pressure ulcer management is a general term to describe a support surface that totally replaces the standard mattress.  Mattress replacements may be constructed of foam, air, gel, or water.  The mattress replacement may be designed to provide a function such as static air, alternating air, low air loss or immersion.  Once again, patient assessment is matched to the performance of the support surface. Another way to categorize a mattress replacement is: 




3.  Full-framed specialty bed is a general term to describe a pressure management support surface that is a totally integrated bed system, consisting of mattress and bed frame.  The full-framed specialty bed replaces the entire conventional bed.  The pressure management support surface is usually constructed of air, gel or water, or a combination of ingredients.  Depending upon the composition, the function may be alternating, low air loss, high air loss, lateral rotation or immersion.

 Water immersion beds



Clinical application of support surfaces begins with a methodological approach to the selection of the appropriate surface.   Many types of support surfaces have been devised to prevent and treat pressure ulcers.  These surfaces have evolved to take on various forms and functions, with different features and benefits.  Rather than a case by case choice, the process is simplified by determining a standardized method for decision making.

Decisions concerning support surfaces are made within the framework of the patient care plan.  This process takes into consideration two factors;

  • patient assessment

  •  support surface assessment 

Criteria for patient assessment may include determining the risk for development of pressure ulcers.  Several tools are available which have been validated through clinical research.  These include:

  • Braden Scale

  • Norton Scale

Another method of assessment involves consideration of available patient turning/sleep surfaces. 

Whatever the patient assessment is based upon, the goal is to match the patient need with the features provided by the support surface.  The next question is what form and function does the surface provide and can it meet the needs of the patient.  


One example of a methodology is Select The Optimal Patient Support Surface (S.T.O.P.S.). *

Click this picture to see a much larger image.

In today’s healthcare arena, other criteria may also influence the decision making process.  These criteria may include cost, ease of use, and support and service provided by the manufacturer. 

Populations within certain clinical areas may present with specialized needs related to support surfaces. 

  • One clinical area that presents with specialized needs is the peri-operative arena. Due to constraints imposed by patient positioning on surfaces that may not address pressure and shear there is the potential for tissue damage.  Surgical procedures of greater than 2 hours and procedures that involve the cardiovascular systems may cause an otherwise low risk patient to be at high risk.  Any patients undergoing procedures of longer than 2 hours may be considered to be at risk for pressure ulcers.

  • Emergency department procedures and protocol may cause individuals to spend long periods of time reclining on surfaces that do not reduce or relieve pressure and shear. 

  • Patients in intensive care units often have critical or life threatening conditions and co-morbidities that increase their risk for pressure ulcer development.  Many of these patients are either immobilized to some degree or are not able to be moved due to instability of vital signs. 

  • Residents in transitional care units and skilled nursing units may have special needs due to immobility or existing chronic wounds. 

  • Hospice patients may also have special needs for support surfaces.  Maintaining the highest level of comfort may be the primary objective with the terminally ill.  The performance of a support surface related to pain management becomes the focus. 

Regardless of the care setting, each clinical area and each individual within those clinical areas must be assessed and their needs must be matched to the appropriate support surface.  The methodology is a universal one and can be applied in any care setting.  Pressure ulcer prevention and treatment must include support surfaces and any plan of care that omits support surfaces is incomplete.

 *  Call Gaymar Industries, Inc. for references


Other companies with support surface products include:

  • Chestnut Ridge

  • DeRoyal

  • EHOB,Inc

  • Gaymar

  • Hill-Rom

  • Huntleigh

  • KCI

  • Keen Mobility

  • Mason Medical Products

  • Medline

  • Span-America

  • Tempur-Pedic

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