Key principles of seating

Sitting can cause pressure injuries and harm skin integrity, if not managed correctly. This section outlines some of the risks and techniques to consider when maintaining healthy skin care in a person with an SCI.

Offloading

Offloading refers to temporarily shifting or relieving weight from pressure points. While pressure-relieving equipment is useful, it does not remove all pressure or the need to reposition and do regular pressure relief.

Offloading is one of the most important ways to prevent pressure injuries and repositioning should occur every 30 minutes, for at least 60 seconds, to maintain skin integrity.

There are a variety of offloading techniques:

Lean: this can include leaning forward, over the knees, or from side to side.

Lift: a full lift, clearing the seated surface.

Tilt: using the mechanics of the power drive or manual wheelchair, by tilting (not reclining) greater than 45 degrees.

Maximise surface area contact

Pressure equals mass per unit area and, when sitting on a flat firm surface, the ischial tuberosities (the curved bones at the bottom of the pelvis) take most of the seated body weight. It is possible to increase the contact surface area and minimise pressure, by distributing weight to the greater trochanters and onto the back of the thighs. This is best done with immersion.

Minimal contact with the surface means higher pressure over a smaller surface area.

Immersion improves pressure distribution, by distributing weight over a larger surface area.

Common issues affecting pressure distribution in sitting:

Cushion

  • Incorrect setup can mean the air cushion may be over or underinflated: both can cause high pressure over the ischial bones.
  • Inadequate gel or incorrect well width on the cushion can cause the person to ‘bottom out’ through the gel.
  • Incorrect dimensions, such as too short depth or width, can cause problems with the thigh and/or greater trochanter, and causing the person to slide forward in the chair.

Footplate height

  • Neutral knee positioning is ideal.

Seat rake/squeeze

  • Too much seat rake/squeeze can increase ischial pressure.

Maintaining or improving postural alignment

  • Teach the person with SCI to check with a mirror, take a photograph or have someone else check their skin.
  • Perform a postural assessment to determine issues and solutions.
  • Start at the hips, to provide a stable base of support (being mindful of cushion selection, such as air or gel), and then assess above and below the hips.
  • Comfort and functional independence are crucial in improving compliance and increased sitting tolerance.

Key considerations for postural alignment:

  • The back support fits the person, not the chair.
  • Lateral support should provide correct alignment without impacting functions, such as propulsion or transfers.
  • The correct height of the back support without impacting functions, such as propulsion.
  • Correct height and positioning of armrests.

Generic wheelchair and cushion considerations

  • Check the wheelchair and cushion are well maintained.
  • Educate the person on how to check and maintain correct cushion pressures. The cushion should be checked daily, to see that it is correctly placed on the wheelchair and in working order.
  • Wash cushion covers regularly, as this will reduce bacterial growth on the cover.
  • Metal sections on the wheelchair will heat up in hot environments and can cause burns.