Choosing the Right Surface for the Right Reason

Photo of a Comfort Zone MattressSupport surfaces are an integral intervention for both the prevention and treatment of pressure ulcers; however, the terms and definitions associated with support surfaces have been extremely inconsistent for many years. Many groups have attempted compiling a comprehensive set of definitions to help clinicians determine the appropriate support surface based on patient need.

The Centers for Medicare and Medicaid Services (CMS) has divided support surfaces into three groups. Support surfaces are generally designed to either replace a standard hospital or home mattress or as an overlay placed on top of a standard hospital or home mattress.

Group 1: Products in this category include mattresses, pressure pads and mattress overlays (foam, air, water, or gel).

Group 2: Products in this category include powered air flotation beds, powered pressure-reducing air mattresses, and non-powered advanced pressure-reducing mattresses.

Group 3: Support surfaces are complete bed systems, known as air-fluidized beds, which use the circulation of filtered air through silicone beads.

The National Pressure Ulcer Advisory Panel (NPUAP) also has attempted to compile a set of definitions. In 2001 the NPUAP research subcommittee established the Support Surface Standards Initiative or S3I. This group was formed to help fill the need for performance and reporting standards for support surfaces. With the recent affiliation with ANSI/RESNA, S3I becomes the official standards body for the United States. As a result of this expanded role, NPUAP has made S3I a continuing subcommittee under the Research Committee with the charge to implement appropriate standards.

Historically we have had many terms and not a lot of clarity, for example, static and dynamic, which refer to conditions or states of activity and ultimately have come to mean powered and non-powered. Also we've had the terms pressure reduction and pressure relief.

Pressure defines the amount of force over an area and relief indicates weightlessness. Because a person cannot be weightless, they cannot be free of pressure. Therefore, pressure reduction is the preferred terminology.

During the review of terminology used across the continuum, it became clear that many other terms were either misused or confusing. A subgroup of S3I was formed to compile a set of terms that provides a common understanding of basic physical concepts, design considerations and product characteristics.

Terms associated with support surfaces

The following is a snapshot of the terms associated with support surfaces that will assist clinicians in making informed decisions when choosing support surfaces for their patients.

  • Active Support Surface - A powered support surface with the capability to change its load distribution properties, with or without applied load.
    • The surfaces constantly evaluate the patient's weight and position and adjust automatically to maximize weight redistribution.
  • Air Fluidized Therapy - A feature of a support surface that provides pressure redistribution via fluid-like medium created by forcing air through silicone beads as characterized by immersion and envelopment.
  • Alternating Pressure - A feature of a support surface that provides pressure redistribution via cyclic changes in loading and unloading as characterized by frequency, duration, amplitude, and rate of change parameters.
  • Closed Cell Foam - A non-permeable structure with a barrier between cells that prevents gases or liquids form passing through the foam.
  • Elastic Foam - A type of porous polymer material that conforms in proportion to the applied weight. Air enters and exits the foam cells more rapidly, due to greater density (non-memory).
  • Fatigue - The reduced capacity for a surface or its components to perform as specified. This change may be the result of intended or unintended use and/or prolonged exposure to chemical, thermal, or physical forces.
    • Support surfaces should be inspected daily with hand checks to help evaluate for bottoming out. Surfaces also should be checked regularly for compromise of cover integrity to prevent internal contamination.
  • Friction (Frictional Force) - the resistance to motion in a parallel direction relative to the common boundary of two surfaces.
    • The greater the perpendicular force or pressure at the same time as the parallel force, the greater the risk for skin damage.
  • Gel - A semisolid system consisting of a network of solid aggregates, colloidal dispersions or polymers which may exhibit elastic properties (can range from hard gel to soft gel).
  • Integrated Bed System - A bed frame and support surface that are combined into a single unit whereby the surface is unable to function independently.
  • Lateral Rotation - A feature of a support surface that provides rotation along a longitudinal axis as characterized by degree of patient turn, duration, and frequency.
  • Low Air Loss - A feature of a support surface that provides a flow of air to assist in managing the heat and humidity (microclimate) of the skin.
    • Most low air loss surfaces are designed to also detect patient weight and position change in order to maximize weight redistribution while maintaining an optimum microclimate.
  • Mattress - A support surface designed to be placed directly on the existing bed frame.
    • Mechanical Load - External force applied to the skin as a result of contact with another surface. Examples:
      • Pressure - Perpendicular to the skin surface.
      • Friction - Mechanical surface damage caused by skin rubbing against another surface.
      • Shear - Mechanical force parallel to another area.
    • Magnitude and time are indirectly proportional 
  • Non-Powered - Any support surface not requiring or using external sources of energy for operation.
  • Open Cell Foam - A permeable structure in which there is no barrier between cells, and gases or liquids can pass through the foam.
  • Overlay - An additional support surface designed to be placed on top of an existing surface.
  • Powered - Any support surface requiring or using external sources of energy for operation.
  • Pressure - The force per unit area exerted perpendicular to the surface.
    • Measured in pounds per square inch (psi).
    • Affected by immersion and envelopment, weight distribution and tissue composition.
  • Pressure Redistribution - The ability of a support surface to distribute load over the contact areas of the human body. (This term replaces prior terms pressure reduction and pressure relief.)
    • The amount of skin to surface contact, along with immersion and envelopment, determines the degree of redistribution.
  • Self-Adjusting or Reactive Support Surface - A powered or non-powered support surface with the capability to change its load distribution properties only in response to applied load.
  • Viscoelastic Foam - A type of porous polymer material that conforms in proportion to the applied weight. The air exits and enters the foam cells slowly, which allows the material to respond slower than a standard elastic foam (memory foam).

Choosing a support surface

Decisions about which support surface to use should be based on cost considerations and an overall assessment of the individual, including:

  • Identified level of risk
  • Skin assessment
  • Comfort
  • General health/comorbid conditions
  • Mobility

As with any clinical decision, many other components must be taken into consideration when making support surface recommendations and some may not be appropriate for use in all circumstances. Decisions must take into account:

  • Available resources
  • Local services, policies and protocols
  • The patient's circumstances and wishes
  • Available personnel and devices
  • Experience and knowledge of the end user

Source: Healthy Skin, June 2013