Materials Seating systems employ a variety of materials, including latex foam, viscoelastic foam, solid gel, viscous fluid, air, water, plastics, and combinations of these materials. Materials react differently in terms of density, envelopment, temperature retention, recovery, and other characteristics. Typically, linear, contoured, and molded systems can use most of these materials and sometimes two or more in combination. Determining the most appropriate material is an important part of the evaluation. The materials used directly impact pressure distribution, stability, and comfort. The upholstery is another important part of a seating system. A thick vinyl cover can impede the properties of the material underneath. A porous cover can allow urine to soak into foam, leading to odor, bacterial growth, and destruction of foams.
Other covers may increase friction, which increases risk to skin but improves stability. Stretchy covers increase envelopment (immersion) but offer less stability and can lead to the client sliding forward. Many cover materials are available to maximize the effectiveness of the seating system. Incontinence covers, typically placed under the primary cover, are also available. Previous sections have addressed strategies to provide adequate postural support. For clients with significant loss of muscle strength, molded seating is often required to provide the intimate contact needed to prevent postural collapse. In children, muscle weakness in combination with a growing body quickly leads to orthopedic asymmetries, such as spinal curvatures. Molded seating can minimize this risk and is appropriate, despite anticipated growth and other changes.
CLINICAL CONSIDERATIONS
Pressure is experienced by all wheelchair users and must be addressed by specific strategies to prevent pressure injury development. Other clinical considerations – such as vision and posture and various medical procedures, including tone management strategies – directly affect postural control. For this reason, this course will further explore seating requirements in Pressure injuries Pressure injuries, also referred to as pressure ulcers or sores, are caused by decreased blood flow to tissue due to compression (ischemic pathway) or to tissue deformation (tissue deformation pathway; Brienza, 2018). Common areas for pressure injuries include the buttocks, sacrum, elbows, hips, heels, ankles, shoulders, back, and back of the head (Brienza, 2018). A major consideration in seating recommendations is preventing pressure injuries. Staging According to the National Pressure Injury Advisory Panel (2016), a pressure injury is defined as follows: localized damage to the skin and underlying soft tissue usually over a bony prominence or related to a medical or other device. The injury can present as intact skin or an open ulcer and may be painful. The injury occurs as a result of intense and/or prolonged pressure or pressure in combination with shear. The tolerance of soft tissue for pressure and shear may also be affected by microclimate, nutrition, perfusion, co- morbidities and condition of the soft tissue. Pressure injuries are staged or categorized, often by a wound care specialist. The stage of the wound determines treatment. Normal skin is made up of the epidermis and dermis, below which lies adipose tissue, muscle, and bone. In a Stage 1 pressure injury, the skin is intact, but an area of erythema (redness) is present, which is non-blanchable (Figure 13). This type of pressure injury is typically over a bony prominence. In a Stage 2 pressure injury, there is a partial-thickness loss of skin with exposed dermis. This loss results in a shallow open injury with a red-pink wound bed. In a Stage 3 pressure injury, a full-thickness skin loss occurs with adipose (fat) visible, and slough may be present, along with undermining and tunneling. In a Stage 4 pressure injury, there is full-thickness skin and tissue loss with exposed fascia, muscle, tendon, or bone. Slough or eschar (dead tissue that falls off healthy skin) may be present. Finally, some pressure injuries are unstageable, with full-thickness skin or tissue loss and depth unknown because it is obscured by slough and/or eschar. Sometimes the term “deep tissue injury” is also used. This term describes a discolored localized area of intact skin or a blood-filled blister covering underlying soft tissue damage resulting from pressure and/or shear (National Pressure Injury Advisory Panel, 2016).
relation to these considerations. Special considerations involving clients with degenerative conditions involve their possible loss of postural control and changing seating needs. Finally, clinical considerations include postural care, which is a 24-hour approach to managing a client’s posture, particularly addressing positioning during sleep.
Figure 13: Pressure Ulcer Stages
Note. From “Prevention and Treatment of Pressure Ulcers: Quick Reference Guide,” by the National Pressure Ulcer Advisory Panel, 2014, retrieved from http://www.npuap.org/wp-content/ uploads/2014/08/Updated-10-16-14-Quick-Reference-Guide-DIGITAL- NPUAP-EPUAP-PPPIA-16Oct2014.pdf . Used with the permission of the National Pressure Ulcer Advisory Panel, 2014. Contributing factors Pressure injuries are generally the result of pressure or compression to body tissue. Therapists sometimes use measurements such as the Braden Scale to help determine risk factors (Ang, Chang, & Tay, 2014). Many other factors contribute to the development of a pressure ulcer, including the following: ● Heat. ● Moisture. ● Poor pressure distribution. ● Lack of sensation.
● Incontinence. ● Poor hygiene. ● Poor nutrition. ● History of prior pressure injuries. ● Immobility. ● Friction. ● Shear. ● Inactivity. ● Decreased mental status. (Sving, Idvall, Högberg, & Gunningberg, 2014)
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Book Code: PTNC1023
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