Wheelchair Seating and Pressure Mapping

Abstract

Pressure ulcers remain a common problem, incurring great cost to both clients and the health-care system. The predominant risk factor for pressure ulcers is interface pressure, that is, the pressure exerted between the body and the seating surface. Interface pressure can be measured by pressure mapping systems, and can assist with pressure ulcer risk assessment by identifying areas of high pressure and postural abnormalities, which both increase the risk of pressure damage. Pressure mapping systems are clinically useful for assisting with cushion selection. In the clinic, the pressure-measuring mat is placed between the client and a variety of seating surfaces in turn. The seating surfaces showing high interface pressure or poor pressure distribution are eliminated. Selection is then further refined on consideration of factors such as comfort, ease of transfers, and maintenance. Pressure mapping is also a valuable tool to guide therapists in the adjustment of complex seating systems. The color-coded pressure maps provide useful biofeedback to clients, caregivers, and health professionals on the importance of weight shifts and optimal postural alignment.

Pressure sores probably have existed since the dawn of our infirm species. They have been noted in unearthed Egyptian mummies, and scientific writings have addressed them since the early 1800s. (Revis 2005)

A Case Study

Keywords

Cushions, interface pressure, pressure ulcers, ulcer sores, wheelchair

Introduction

The theme of this case study is the assessment and intervention for an individual with multiple sclerosis in relation to seated posture and pressure ulcer prevention .

The student’s tasks include the following:

• Identifying the main risk factors for pressure ulcers

• Determining from the literature the interventions available to redistribute pressure in sitting, e.g., Sprigle and Sonenblum (2011)

• Considering what practical advice and information should be included when educating clients and carers in pressure ulcer prevention

As a starting point, the student should use should use the following literature for background information:

• 1. Sprigle S, Sonenblum S (2011) Assessing evidence supporting redistribution for pressure ulcer prevention. J Rehabil Res Dev 48(3):203–214

• 2. Hollington J, Hillman SJ (2013) Can static interface pressure mapping be used to rank pressure-redistributing cushions for active wheelchair users? J Rehabil Res Dev 50(1):53–60

• 3. Moore Z, van Etten M (2011) Repositioning and pressure ulcer prevention in the seated individual. Wounds 7(3):34–40

Overview of the Content

Major goal(s) of the intervention include:

• Maximize pressure distribution at the seating surface.

• Educate the client and carer on the importance of maintaining good sitting posture.

• Reinforce the need to self-manage pressure by regular offloading of the bony prominences.

Learning Objectives

By the end of studying this chapter, the learner will:

• 1. Identify the key intrinsic and extrinsic risk factors for pressure ulcer development.

• 2. Realize the importance of completing a detailed seating and pressure care assessment.

• 3. Explain how posture contributes to the risk of developing pressure ulcers.

• 4. Understand the clinical application of pressure mapping systems.

The Background History of the Case Study

Personal information:

Bill (Pseudonym) is a 64-year-old retired school caretaker. He lives with his wife in a single-storey house. He has a level-access shower and requires the use of a hoist for all transfers. Bill is dependent on his wife and formal carers and requires the assistance of two people for all activities of daily living . He has a body mass index of 18.3 (height 178 cm, weight 58 kg).

Medical information:

Bill was diagnosed with relapsing remitting multiple sclerosis (MS) 20 years ago. He displays mainly physical limitations. He is currently immobile and has been wheelchair dependent for the past 10 years. He has spasticity in both his lower and upper limbs and has low tone around his trunk. His score on the Braden Scale (Bergstrom et al. 1987) is 14, indicating that he is at moderate risk of pressure ulcer development.

Occupational therapy interventions:

A tilt in space wheelchair with a viscoelastic foam cushion was issued by his occupational therapist. Twelve months later, at a pressure mapping review clinic, the occupational therapist therapy staff noted the following in relation to a pressure map recorded on his current seating and cushion: (1) poor distribution of pressure under the right femur, (2) sitting in posterior pelvic tilt as shown by contact at the sacrum, and (3) high interface pressure over all three bony prominences in contact with the cushion (both ischial tuberosities and sacrum). Using the pressure mapping protocol described in Chap. 16 above, the occupational therapist checked the adjustable parts of Bill’s wheelchair and found that the right footplate was set 1 cm too high. Lowering of the footplate allowed Bill’s right femur to immerse into the cushion and significantly improved the pressure distribution at the seating surface. A further two alternative cushions were then selected based on Bill’s risk level, posture, stability, and comfort, and pressure maps were recorded on both. However, the originally prescribed viscoelastic cushion still remained the optimal choice when the adjustment was made to his footplate position. The occupational therapist ensured that Bill’s posture was more upright to avoid contact between the sacrum and the cushion, and both Bill and his wife were educated on the importance of maintaining this posture and not adjusting the configuration of the wheelchair. The importance of using the tilt in space feature of the wheelchair to regularly offload pressure from the ischial tuberosities was re-emphasized. A review appointment was planned for 6 months later or earlier if requested.

The Student’s Report

These questions are generated from the literature and our clinical experiences:

• 1. What areas of the body are at risk of pressure ulcers in sitting?

• 2. Which sitting postures increase the risk of developing pressure ulcers?

• 3. How do pressure-reducing cushions work?

• 4. What are the benefits of using a pressure mapping system?

• 5. How important is comfort when selecting a pressure-reducing cushion?

• 6. Why is using tilt in space important for Bill?