Module 8 - Pressure Management

Applying principles of pressure management in seating and wheeled mobility

1. Select products that are designed to maximise contact with support surface and minimise localised pressure through:

Immersion: "Depth of penetration (sinking) into a support surface" *

Immersion increases contact surface to distribute weight. The higher the profile of an "immersion type" cushion, the deeper the immersion to maximise pressure redistribution on the support surface. Client's immersion in the cushion is assessed by tactile inspection or a hand check under the ischial tuberosities.
- For example, the ROHO® low profile cushion has a 2.5 inch/60mm cell height, allowing a 1½inch/ 40mm potential for immersion, while ROHO® high profile cushion has a 4inch/100mm cell height which allows a 3½inch/90mm potential for immersion.
- Some commonly used products that have good immersion are ROHO®, Jay® Deep Contour, Jay® 2 and Vicare®.
There are many air- and fluid-filled cushions available from suppliers. While the immersion principle applies, the designs and maintenance requirements vary between products. It is important to understand the manufacturers' recommendations of product applications and maintenance.

Envelopment: "The ability of a support surface to conform, so to fit or mould around irregularities of the body"*

A support surface with good envelopment contours to the shape of the client's bony prominence/body shape, thus reducing localised pressure. It allows the support surface to mould closely to the client's shape and clothing.
Good envelopment properties are displayed in:
- highly contoured foam cushion and back support
- air- and viscous fluid-filled cell/bladder on support surface
- Envelopment-designed products include:
  - foam in place or contoured seating systems such as Otto Bock® Shape System, Invacare® Shape Sensor Silhouette Seating System and Matrix Shaping Technology System
  - ROHO® High Profile Select range, Jay® Deep Contour cushions with positioning accessories, and Invacare® MSS Flo-tec Solution Xtra Modular Systems can be highly customised to the shape of the clients.
Conversely, covering the support surface with a non-stretch material or a high surface tension such as incontinence pads, sheep skins and draw sheets reduces the envelopment property of the support surface. A high stiffness support surface does not have good envelopment property. More on materials properties:
- "Terms and definitions related to support surfaces", National Pressure Ulcers Advisory Panel 2007, accessed 2008.
- "Wheelchair Cushion Differences" Stephen Sprigle, Ph.D., PT.Spinlife.com, accessed 2008.

This web page is managed and authorised by Greater Metropolitan Clinical Taskforce. Last updated: 16 March, 2009