As described above, both the magnitude and duration of tissue loading are important in the prevention of pressure ulcers. When a pressure ulcer is present, managing the duration and magnitude of loading requires a greater level of attention and is accomplished by using bed support surfaces and wheelchair cushions. These devices are designed to redistribute pressures away from the primary load-bearing parts of the body that are the areas at highest risk for skin breakdown. Clinically, managing the duration of loading is accomplished with postural changes that redistribute loads away from tissues for periods of time (eg, with turning schedules for persons in bed and with weight-shifting activities for persons sitting in wheelchairs). In addition, some cushions and support surfaces can actively change their load redistribution properties to reduce the duration of loading.
Research has not defined a specific threshold for an acceptable magnitude of pressure on tissues. This is not surprising considering the variation in physiology and tissue biomechanics of people at risk for pressure ulcers. Without a clear mandate of acceptable loading on the tissues, clinicians are challenged to manage loads through interventions that must take into account ever-changing technology and the idiosyncrasies of any particular patient. Decisions about appropriate interventions can be facilitated by a working knowledge of support surfaces and positioning technologies, as well as the benefits and deficiencies of the different designs.
CASE STUDY INTRODUCTION
Mrs. S is an 82-year-old frail white female with a history of diabetes mellitus (last hemoglobin A1c-8.0), hypertension, congestive heart failure with an ejection fraction of 35–40%, chronic kidney disease with a baseline creatinine of 2.1, atrial fibrillation on Coumadin therapy, and osteoporosis. Mrs. S lives alone in her own home and is able to do most of her activities of daily living without assistance. She is sometimes incontinent of urine, but is continent of bowels. She ambulates with a rolling walker. She was in her usual state of health until she sustained a fall in her home after slipping on a rug. She was able to call 911 and when paramedics arrived, she complained of right hip pain. She was taken to the ER for evaluation. Hip films revealed a right intertrochanteric fracture. The patient was evaluated by the orthopedic surgeon, but will require risk stratification prior to surgery due to her multiple co-morbidities.
What factors place this patient at risk for pressure ulcer development?
She is being admitted to the hospital. What strategies can be implemented to minimize her risk of skin breakdown?
Mrs. S was admitted to the surgical floor and put in Buck’s traction until she could be cleared for surgery. She is placed on oxycodone/acetaminophen pain medication by the attending physician to help control her pain. She also has a zolpidem prescription for sleep. On day #2 of hospitalization, the patient is noted by her family to be confused. Because of the traction, she is now incontinent of bowel and bladder. The patient is noted to have redness on the right heel that is not blanching.
What was the patient’s Braden score on admission? What risk level did that make her?
What is the patient’s Braden score at this point in the clinical history?
What additional factors have put this patient at higher risk for pressure ulcer formation?
Mrs. S undergoes surgical intervention to repair the hip fracture. She receives a total hip arthroplasty and postoperatively is at full weight-bearing status. At postoperative day #5, she is found by the nursing staff to have a blood-filled blister on the right heel. In addition, she is found to have a superficial area of skin breakdown on the sacrum. The wound is partial thickness and there is no evidence of necrotic tissue. She is scheduled to start physical therapy, but there is concern about the heel breakdown. As a result of Mrs. S’s immobility and the pain medication she is receiving, she has been having issues with constipation. This has caused her to have decreased appetite.
How would the patient’s heel pressure ulcer be staged?
How would the patient’s sacral pressure ulcer be staged?
What elements of the wound examination would be used to thoroughly document this wound?
Mrs. S’s heel now has soft necrotic tissue with surrounding erythema, light serous drainage with associated odor, and pain. She is limited in her ability to do physical therapy by the pain in her foot. The patient’s sacral pressure ulcer now has a thin layer of yellow slough, but no evidence of periwound erythema. There are no signs or symptoms of infection. The attending physician wants to transfer the patient to a skilled nursing facility for ongoing physical therapy and wound care, but they need recommendations on how to treat the pressure ulcer on the heel and the sacrum.
What debridement techniques are optimal for the patient’s heel given her clinical picture? For her sacrum?
What are the possible complications that can occur due to the deterioration of the heel?
Support Surfaces: Beds, Mattresses, and Overlays
Horizontal support surfaces (such as bed systems, mattresses, and overlays) play a large role in managing tissue loads, especially in the many environments where people are in bed for extended periods, are potentially immobile, and have co-morbidities and/or injuries that weaken the body. Being comfortable with the terminology used to characterize and describe horizontal support surfaces is important for any clinician when reading research about this technology and when communicating with other professionals about appropriate interventions. The National Pressure Ulcer Advisory Panel (NPUAP) has developed a list of common terms and definitions for such purposes.11 TABLE 6-3 lists several categories and features of support surfaces and their respective definitions, and FIGURES 6-6 to 6-9 illustrate some of the designs.
Categories and Features of Support Surfaces
||Download (.pdf) Table 6-3
Categories and Features of Support Surfaces
|CATEGORIES OF SUPPORT SURFACES |
|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 |
|Active support surface ||A powered support surface with the capability to change its load distribution properties, with or without applied load |
|Non-powered ||Any support surface not requiring or using external sources of energy for operation |
|Powered ||Any support surface requiring or using external sources of energy for operation |
|Integrated bed system ||A bed frame and support surface that are combined into a single unit whereby the surface is unable to function separately |
|Mattress ||A support surface designed to be placed directly on the existing bed frame |
|Overlay ||An additional support surface designed to be placed directly on top of an existing surface |
|FEATURES OF SUPPORT SURFACES |
|Air fluidized ||A feature of a support surface that provides pressure redistribution via a fluid-like medium created by forcing air through 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 |
|Lateral rotation ||A feature of a support surface that provides rotation about 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 |
Cross-section of support surface A cross-section of a pressure-redistribution surface illustrates the combination of materials, construction, and air flow provided by an external pump. (Hill-Rom® P500 Therapy Surface Mattress Replacement System, Hill-Rom Services, Inc. Reprinted with permission. All rights reserved.)
Active support surface Air is circulated inside cells within the support surface to both immerse and envelope the patient and provide pressure redistribution. This type of powered mattress can be used on an existing bed frame. (Envision® E700 Wound Surface, Hill-Rom Services, Inc. Reprinted with permission. All rights reserved.)
Alternating-pressure, low-air-loss support surface Alternating pressure in achieved by a pump blowing air through chambers to get rhythmic inflation and deflation and thereby redistribute the pressure. The air blowing through the cover reduces the skin/surface interface temperature and reduces the risk of maceration from moisture. Plastic bed liners should be avoided on these beds as the plastic obstructs the flow of the air and holds both heat and moisture against the patient’s skin. (Synergy® Air Elite Mattress Replacement System, Hill-Rom Services, Inc. Reprinted with permission. All rights reserved.)
Air-fluidized bed The air-fluidized bed, an integrated bed system, contains millions of silicone-covered beads that are continuously being blown by an air pump, thereby providing floatation to the patient. These beds are used for patients with multiple pressure ulcers, complex Stage III or Stage IV ulcers, or postsurgical repair with a flap. (Clinitron® II Air Fluidized Therapy Unit, Hill-Rom Services, Inc. Reprinted with permission. All rights reserved.)
Selection of the most appropriate support surface for the patient might be constrained by the hospital or care environment, but generally multiple options will exist. Informed decisions, of course, begin with an evaluation of the patient or client, but also must include basic knowledge of products.
Pressure ulcer risk evaluation is a natural place to start and is combined with assessment of function, including the patient’s ability to reposition in bed and the ability to transfer into and out of bed. Differences in features and design form the basis of an informed clinical decision that is best made by the multidisciplinary team involved in the patient’s care. Some support surface characteristics are technical in nature, such as the quality of component parts, warranty, expected lifespan, and maintenance requirements. For example, a support surface that requires periodic adjustment and maintenance may be appropriate in a facility with the capacity to handle those tasks, whereas it might not be a good choice in certain homecare environments, unless the patient and/or caregivers are comfortable in making those adjustments.
Support surfaces are designed to protect the skin and underlying tissues by allowing the patient to immerse or sink into the surface. Immersion redistributes pressures and envelops the body in an attempt to equalize external forces as much as possible. A support surface must be soft enough to allow immersion without bottoming out. Compliant support surfaces can deflect only so far before they cannot deflect further. This defines a “bottomed-out” state and results in high pressures on tissues. Because achieving an appropriate amount of immersion is so important, the optimal stiffness of the surface must take into account the patient morphology. A surface that is too firm will not allow the person to immerse, whereas one that is too soft might not afford a stable surface for functional mobility (eg, turning and moving in bed). Foam and gel materials generally have a fixed functional stiffness; thus, a surface with appropriate stiffness and thickness needs to be selected in order to provide requisite support. Surfaces using air typically offer adjustability, thereby allowing functional stiffness to be appropriately adapted for each patient. In both cases, reevaluation after selection must be done to insure that the support surface is properly configured to protect tissues and support the body.
Evaluating the Effectiveness of Support Surfaces
A large amount of research has focused on the effectiveness of support surfaces. Some use direct measures of clinical outcomes such as pressure ulcer incidence or time for pressure ulcers to heal. Others use indirect measures, including variables such as interface pressure, blood flow, and temperature. Both approaches have merit but report quite different information about support surface performance. An effective review of the literature requires an assessment of methodologies and devices with respect to how they apply to a particular situation. The patient population (eg, orthopedic, neurological), care environments (eg, ICU, homecare, long-term care), and types of support surfaces may impact how results influence care decisions. Notably, treatment studies—in which subjects already have ulcers—are fundamentally different from prevention studies. For the purpose of this chapter, a select number of comparisons are highlighted as a means to illustrate how studies are configured to investigate effectiveness. Several recent articles and documents have provided an overview of support surface research and can be referred to for more detailed information.12-15
Most studies compare different classes of products as defined in TABLE 6-3 rather than compare similarly designed products. For example, many more studies compare a standard hospital mattress to a specialty mattress instead of comparing two different types of low-air-loss beds. Moreover, studies tend to focus on a specific model from one manufacturer. It would be impossible to study all makes and models that exist in a single support surface category. Any study involving technology has the potential to become outdated simply because technology changes. This does not mean that historical studies have no value; instead it acknowledges the challenge of focusing solely on published literature to make clinical decisions and highlights the need to keep abreast of this ever-changing body of knowledge.
The most common research comparison is against a “standard” hospital bed or mattress. Even though there are differences in what constitutes a standard hospital mattress, the results are clear: standard mattresses are not very effective to prevent or to treat pressure ulcers. Non-powered, constant-low-pressure support surfaces (foam, air, gel, and combinations of these materials) are more effective in preventing pressure ulcers than a standard mattress.12-14 In fact, standards of practice recognize this by mandating the use of alternative surfaces in the plans of care for persons who are at risk for or already have pressure ulcers.
Studies comparing advanced active technologies including low-air-loss, alternating-pressure, and fluidized surfaces tend to find them to be equivocal in effectiveness.16-18 This offers evidence that these types of advanced support surfaces have roles to play in both prevention and treatment of pressure ulcers. Equivocal results should also motivate clinicians to read the literature in order to better understand the results and how the lack of significant results can also be clinically useful. For example, consider a comparison of two support surfaces in preventing pressure ulcers in a critically ill population.8 Sixty-two persons were enrolled and 9 of them developed pressure ulcers. The low incidence of pressure ulcers in this high-risk patient group resulted in an inability to detect differences in the two surfaces. Clearly, too few pressure ulcers are not a bad outcome, so the lack of a difference is still an important finding.
Protecting the Heels and Lower Extremities
For patients in bed, heels are particularly prone to pressure ulcers. This is not surprising if one reflects on the anatomy of the posterior aspect of the heel, the portion in contact with the support surface, and the amount of both direct pressure and friction that occurs at the heel. (FIGURE 6-2) The calcaneous forms a small, narrow prominence that must bear the weight of the foot and part of the leg when the patient is supine. Even though the foot is a small mass, the small surface area results in damaging pressure. In fact, the heel is often cited as the second most common site for ulcers, accounting for 25–30% of pressure ulcers.19,20
Many commercial devices and approaches are available to reduce or eliminate pressure on the heels. Mattresses and overlays are often designed to support the heels using softer materials or different designs than those used to support the rest of the body. Two additional types of devices are available: (1) user-worn boots or heel protectors, and (2) positioners to elevate the heels.
The user-worn approach consists of a boot or pad that encases the foot and heel and attaches directly to the person. (FIGURES 6-10 to 6-12) These can be made from air bladders, foam, gel, or sheepskin materials. These devices remain in place during changes in positioning and as the legs move in bed; therefore, the fit and securement must be assessed. Most user-worn devices help prevent the ankle from plantar flexing (aka, foot drop) and some are designed to keep the ankle and foot aligned even in the presence of tone or spasm via the use of a rigid shell. If, however, the patient already has a plantar flexion contraction, the rigid support is contraindicated because peak pressures will occur at the plantar metatarsal heads and the Achilles tendons, causing the pressure ulcers in these areas. (FIGURE 6-13) Ambulation while wearing heel boots and pads is typically contraindicated (unless there is an ambulation sole attached); thus, these devices are not recommended when encouraging patients to transfer out of bed independently. Many studies have documented interface pressure and other outcomes about various products. Reviews of these studies are often useful;21-24 however, clinicians should read the primary source when using the results of a specific study to determine clinical decisions.
User-worn heel protector The Rooke boot is made of pliable sheepskin-like material that can be worn in bed and for limited ambulation. It is available with a rigid frame to maintain ankle range of motion and without a frame to accommodate plantar flexion contractures.
Rigid ankle-foot orthotic with heel relieved of any contact, both in supine and standing positions
Foam boots with suspended heels
Plantar flexed ankle A plantar flexed ankle that cannot be passively stretched to neutral placed in a rigid AFO will have peak pressures at the metatarsal heads and the Achilles tendon, thus putting these tissues at risk for pressure ulcer formation. Some AFOs have adjustable ankle joints to adapt to plantar flexion contractures.
The other category of heel protection is achieved by elevating (or floating) the heels completely off the surface by placing a positioning pad or pillow under the calf. Although some may extend to the knee, caution is advised with orthopedic patients when support under the knee may lead to knee flexion contractures (eg, after a total knee replacement). Several products can be purchased to provide heel elevation function (FIGURE 6-14) and are made from inflatable bladders or foam. Regular head pillows can be used to elevate the heels; however, they have been shown to be less effective because they compress and get out of position more easily.14 (FIGURE 6-15) Heel elevation devices do not necessarily accommodate changes in position and therefore must be assessed whenever a person returns to a supine posture or moves the legs. In addition, care must be taken not to elevate the foot in a manner that induces hyperextension at the knee, which will become uncomfortable. Any lower extremity positioning approach should be done after assessing ranges of motion at the hip, knees, and ankle to insure that external positioners maintain appropriate joint positions.
Heel and foot elevating pad Pads under the calves are effective in off-loading or floating the heels; however, they may be displaced as the patient repositions. Care must be taken to avoid prolonged pressure on the posterior calf if the patient is insensate or atrophied (eg, a patient with spinal cord injury).
Pillows used to off-load the heels When commercial devices are not available or not adaptable to a patient, pillows can be used creatively to accomplish pressure redistribution. This patient has bilateral foot drop and also tended to slide down in bed, putting the plantar metatarsal heads at risk. A pillow under the calves floats the heels and a folded pillow between the feet and the end of the bed off-loads the plantar surfaces. While improvisations may not be ideal, they can be effective when combined with frequent repositioning.
Positioning people in varying degrees of side-lying requires padding and positioners to insure bony prominences are adequately protected. (FIGURE 6-16) The malleoli and knees can be subjected to high pressures when in side-lying. These issues are discussed in the section on recumbent postures.
Thirty-degree side-lying posture Thirty-degree side-lying posture uses a foam wedge for positioning and pillows under the arms and legs and between the knees to protect bony prominences of all extremities and the sacrum. Folded pillows may be used behind the back and sacrum if foam wedge is not available. (Used with permission of Stephen Sprigle PT, PhD.)
Wheelchairs and Wheelchair Cushions
People who use wheelchairs are as varied as people who ambulate. They exhibit a wide range of medical diagnoses, but share the functional limitation of being non-ambulatory or unable to ambulate functionally or safely. Because many wheelchair users sit throughout the day, many are at risk of developing pressure ulcers. Wheelchair users are assessed with respect to two common pressure-ulcer risk factors, immobility and sensation. Persons who are unable to recognize pain or discomfort while sitting are naturally at high risk for developing ulcers. Similarly, persons unable to move in their seat or to shift weight and correct posture are also at heightened risk. In both cases, these wheelchair users will be unable to recognize when damaging loads are placed on their skin and subcutaneous tissues.
Sitting-acquired pressure ulcers typically present at the load-bearing parts of the pelvis, specifically the ischial tuberosities and sacrum/coccyx. (FIGURE 6-17) However, pressure ulcers can arise in other anatomical locations if the magnitude and duration of loading exceeds levels that the tissue can withstand. Other sites can be at risk in response to poor positioning within the wheelchair, including the scapular region, head, lateral trunk, knees, and feet. Therefore, proper positioning and body support are important in the prevention and management of pressure ulcers.
Vulnerable areas when patient is sitting in wheelchair The most vulnerable areas for skin breakdown when a patient is sitting in a wheelchair include the ischial tuberosities, sacrum, coccyx, scapula, head (when using high-back chairs), lateral trunk, knees, and feet. (Used with permission from Powers JG, Odo L, Phillips TJ. Chapter 100. Decubitus (Pressure) Ulcers. In: Goldsmith LA, Katz SI, Gilchrest BA, Paller AS, Leffell DJ, Wolff K. eds. Fitzpatrick’s Dermatology in General Medicine. 8th ed. New York, NY: McGraw-Hill; 2012. http://www.accessmedicine.com/content.aspx?aID=56053262. Accessed May 19, 2013.)
Wheelchair Positioning and Fitting
Wheelchairs are not a one-size-fits-all piece of equipment. Because wheelchairs are functional devices, wheelchair users are assessed from both functional and medical perspectives. Proper fit of the wheelchair to the individual is of utmost importance.
Several common problems arise when a wheelchair is poorly fitted to the wheelchair user. These include:
▪ Sliding out of chair
▪ Poor sitting tolerance
▪ Lateral trunk instability
▪ Poor thigh/foot stability
▪ Inability to reach the ground to propel
▪ Inability to hand propel effectively
These problems result in an increased risk of skin breakdown because postural problems due to inadequate body support result in high pressures at areas of bony prominences. For example, a poorly fitted wheelchair seat can encourage a person to slide forward on the seat. This results in the pelvis rotating posteriorly and exposes the sacrum and coccyx to unnecessary loading. Lateral trunk instability can result in a person leaning against the backrest upright, which results in a pelvic obliquity that elevates pressure on one ischial tuberosity and can cause high localized pressure on the lateral trunk.
Six wheelchair measurements are considered when configuring a wheelchair to a person: seat height, seat width, seat depth, backrest height, footrest height, and armrest height. (FIGURE 6-18) Seat height, seat width, seat depth, and backrest height are dimensions that are usually selected when ordering a wheelchair. Conversely, footrest height can be adjusted on nearly all wheelchairs, and most chairs permit armrest height adjustment. These features can, therefore, be matched to the individual during the fitting process.
Wheelchair dimensions to consider when fitting a chair for the individual (Used with permission from WoundZoom, Inc.)
A poorly-fitting wheelchair has a detrimental impact on posture, thereby resulting in decreased function and increased loading on the buttocks. A slouched kyphotic posture is the most common poor posture resulting from an inadequate wheelchair and seating system. This posture is characterized by a posterior pelvic tilt and kyphotic spine. A slouched posture elevates pressure at the sacrum and coccyx and the resulting increased forward sliding tendency exposes the tissues to friction and shear strain. TABLE 6-4 lists some common postural impacts of a poorly fitted wheelchair.
Common Postural Changes in a Poorly Fitting Wheelchair
Wheelchair cushions are required for all wheelchair users because wheelchair seat upholstery is simply not designed or intended to offer adequate support. The selection of wheelchair cushions for persons identified to be at risk of pressure ulcers is obviously more involved and requires more attention than selection of a cushion for a person with intact sensation and adequate mobility who uses a wheelchair for only short durations of time. Many wheelchair users sit in their wheelchairs throughout the day, sometimes for 12 hours or more.21,23
Hundreds of cushions are commercially available, so many options exist for both full-time and part-time wheelchair users. A basic understanding of materials, design, and performance can assist the clinician in selecting appropriate cushions for wheelchair users. The two most important things to remember are: (1) no one cushion is best for all people, and (2) cushion selection must reflect the needs, function, and activities of the wheelchair user. The second point highlights the fact that cushions serve other roles besides managing loads on tissues. Cushions impact many aspects of functioning during everyday activities, including posture, comfort, transfers, heat and moisture of the cushion interface, and a host of other factors. In addition, the environment of use, amount of use, and activity level of the user influence cushion selection. A person who sits in a wheelchair for 16 hours a day and travels outdoors over a variety of surfaces has different needs than a person who sits in a wheelchair for 2 hours per day because he or she transfers into other chairs and surfaces. Clinicians use their skills to evaluate their clients and patients in order to select an appropriate cushion. Therefore, combining the functional impact of cushions with requirements to promote skin health is the appropriate approach.
Most wheelchair cushions can be described as reactive and non-powered. Although a few powered, active cushions do exist, they are not commonly used except in complex situations (eg, a person with a history of multiple pressure ulcers). Cushions can be flat or contoured, and are designed to deform and deflect to accommodate the buttocks.
Wheelchair cushions are made from a variety of materials and reflect many designs. Four materials dominate cushion design: foam, air, viscous fluid, and elastomers. Foam cushions are the most common; however, most advanced cushion designs use a combination of materials with the intent of maximizing cushion performance by managing the good and poor features of each material. TABLE 6-5 lists these common materials, some of the beneficial features, and their limitations. FIGURE 6-19 illustrates the myriad cushions fabricated with different materials. Functionally, cushions can be categorized by their skin protection and positioning capabilities. In the United States, these categories are often used by insurance companies and other third-party payers. Although many cushions are designed to provide both functionalities, the following sections discuss the rationale behind these general categories.
Table 6-5Common Materials Used in Cushion Construction ||Download (.pdf) Table 6-5 Common Materials Used in Cushion Construction
|Material ||Benefits and Reasons for Use ||Drawbacks |
|Foam ||Inexpensive; comes in many stiffnesses, can be carved, cut, and molded easily; lightweight; good resilience and damping properties. ||Heat insulator, so entraps body heat; needs to be protected from light and moisture; can have short lifespan. |
|Air ||Lightweight; offers adjustability; good impact, damping, and resilience. ||Impermeable bladder impacts cushion mass, can hinder effectiveness and heat management; inflation needs to be checked regularly; can be punctured. |
|Viscous fluid ||Displaces in response to load to envelop the buttocks; some fluids provide heat transmissibility. ||Can be heavy; poor resilience and impact damping; creep over time can reduce performance; its impermeable bladder can hinder effectiveness and heat management; nonadjustable. |
|Elastomer ||Used as a top layer to envelop the buttocks and dissipate heat. ||Can be heavy and expensive; incompressible, so must be used with other materials to fully envelop; poor impact damping; can creep over time. |
Wheelchair cushions Designs of wheelchair cushions highlighting various materials of construction. (Used with permission, Stephen Sprigle, PT, PhD.)
Cushions designed for skin protection target loading on the skin, as well as adequately managing temperature and moisture at the buttock-cushion interface. In addition, they offer a stable base of support. In the seated posture, loading on the buttocks represents the greatest risk for tissue damage. Cushions attempt to redistribute pressures away from bony prominences such as the ischial tuberosities and sacrum/coccyx. Two general techniques are followed: (1) envelopment and (2) redirection or off-loading.
Envelopment is defined as the capability of a support surface in deforming around and encompassing the contour of the human body.25 To properly envelop, cushions must deflect and deform to immerse the buttocks in the material. Due to the design of the pelvis, about 4 cm of immersion is needed to adequately encompass the buttocks. This is based on the inferior position of the ischial tuberosities during sitting. (FIGURE 6-20) As a result, cushions need adequate thickness to permit that amount of immersion. Foam cushions that are only 5 cm (2˝) thick will probably not suffice as skin protection cushions.
Anatomic relationship between the inferior aspects of the ischial tuberosity and greater trochanter (Used with permission, Stephen Sprigle, PT, PhD.)
Some cushions are designed to purposely redirect forces away from bony prominences using cutouts or contours in the cushion surface. (FIGURE 6-21) As a result, cushions with cutouts and contours require the person to sit on the cushion in a specific location, so proper training and instruction should be a part of any cushion fitting session.
Cushions with cutout or reliefs to redirect loading Cushions with cutouts are frequently custom-made to fit the patient’s anatomical dimensions. Because shifting weight in the cushions will change the pressure points, appropriate training and use are required for optimal efficacy.
Postural support is an important factor in cushion selection, just as it is in wheelchair fitting. Cushions are important in facilitating seated functional activities. Positioning can be grossly categorized as alignment, accommodation, or correction; a clinician performs an evaluation to determine which kind of positioning is needed. To properly align the body in an erect and symmetric posture, cushions may include certain features such as contouring for the buttocks, lateral pelvic supports, and lateral and/or medial thigh supports. (FIGURE 6-22) Appropriate cushions do not promote a slouched posture and keep the buttocks from sliding forward in the seat. Clients who sit with a fixed asymmetry (such as a pelvic obliquity) require a cushion that can accommodate a deformity. These cushions often include some adjustable feature, such as adding or removing components or altering the air inflation level. Conversely, if an asymmetry is correctable, a cushion can be used to position a client into a symmetric posture by the same means and thereby correct the faulty posture. Evaluation (including ROM, tone, and functional assessment) is needed to determine which type of positioning is needed.
Flat (A) and contoured (B) cushions with positioning features. (Used with permission from Stephen Sprigle, PT, PhD, © Georgia Tech Research Corporation, Atlanta, GA.)
Positioning features of cushions typically result in a cushion surface that is site specific, meaning that the user must sit on the cushion correctly. For example, sitting too forward on a cushion may result in the person sitting upon the medial thigh support or pommel. Cushions with deep contours or pronounced positioning features are designed to provide a very stable sitting surface. However, these characteristics may also impede function. For example, a contoured cushion with a pommel may be needed to position the lower extremities, but it can also impede transfers if the person cannot overcome this positioning feature. This again underscores the importance of a proper assessment because all cushions will have benefits and deficiencies that must be reconciled for each individual user.
In summary, many wheelchair cushions are commercially available. Having myriad choices can empower clinicians and clients, but choice can also be confusing. By reflecting upon the seating goals for the patient or client and the various cushion materials and designs available, an informed decision can be made.