by Mary Ellen Buning, PhD, OTR/L, ATP, SMS, and Robert M. Meehan, PT, ATP, SMS
As therapists, we have the unique and gratifying opportunity to help patients recover or develop essential daily living skills that enable them to function independently in their homes and communities. Our work allows us to connect and collaborate with patients on an individual level as we learn about their diagnosis, lifestyle, and other personal factors that will influence their treatment plan. In addition to the collaborative patient relationship, therapists rely on a variety of methods and assistive technologies, such as interface pressure mapping (IPM), that help inform and empower the collaborative journey with each patient.
Historically used in research settings, the clinical use of IPM is increasing, and IPM is quickly becoming a valuable tool at rehabilitation facilities and seating clinics nationwide. When used as part of a thorough clinical assessment, IPM can help practitioners, particularly seating and mobility specialists (ATP/SMS), to maximize pressure management, postural symmetry, breathing, comfort, and the overall independence and mobility of the individuals we treat. The Frazier Rehab Institute in Louisville, Ky, part of KentuckyOne Health, sees approximately 2,000 patients annually in its wheelchair seating and mobility clinic for a variety of services. Clinic staff members have been using IPM technology for more than 8 years and value it as an especially useful tool for the prediction and prevention of secondary complications, seat cushion selection for wheelchair users, and an effective and interactive teaching tool.
Preventing Secondary Complications
Preventing secondary disability—primarily, pressure ulcers—is undoubtedly a top priority for ATP/SMS practitioners. In
the US, nearly 50% of the 1.4 million people who rely on wheelchairs for mobility develop serious tissue breakdown at pressure points because of the effects of prolonged sitting without proper pressure relief.
By capturing both momentary and motion data, IPM visually quantifies the patient’s pressure load and helps practitioners to determine the best approach to managing it—load distribution or pressure offloading. As the name suggests, pressure offloading transfers pressure to areas of the pelvis that are more pressure tolerant, such as the posterior ilium or femurs.
Load distribution—the more commonly used approach—works to create maximum buttock surface contact to distribute the patient’s peak pressures from the ischial tuberosities, coccyx, or trochanters as broadly as possible. Both approaches aim to reduce the force created by these bony prominences that vertically load skin, muscle, and soft tissue to levels that are more supportive of blood flow through the capillary blood vessels. Blood flow is essential for O2, nutrition, and the removal of cellular waste products.
Another key issue for effective pressure management is the use of seating cushions and back support products to maintain or restore the lumbar arch. Supporting this arch when sitting enables a neutral pelvis. A neutral pelvis occurs when the anterior superior iliac spine (ASIS) is horizontally aligned with the posterior superior iliac spine (PSIS). Lower abdominal and the pelvic core are required to enable sitting with this alignment and, of course, many patients lack this strength due to paralysis, muscle weakness, deconditioning, or time spent sitting in sling seating. When the lumbar arch is lost, the result is thoracic kyphosis, loss of normal cervical curves, and a chin that juts anteriorly. Improved support of the posterior ilium and the lumbar arch are effective remedies as they prevent loading of the coccyx and the shear created by continuously sliding forward on the seat cushion.
• Flat foam: general purpose, good stability,
envelopment, needs frequent replacement
• Gel or viscous fluid: excellent immersion, insulating
• Air-flotation: excellent immersion, maximal load distribution
• Orthotic: rigid foam, great for offloading/transferring pressure away from bony prominences
• Hybrid cushions: combination air or gel with foam
Efficient Interactive Teaching
Wheelchairs give patients mobility. However, it is important for patients to master essential skills such as transferring into and out of the wheelchair, propulsion, optimal sitting posture, and maneuvering bumps and curves. Knowing that pressure ulcers occur in up to 80% of individuals with SCI, it is critical for SMS practitioners to teach wheelchair skills in a way that patients understand.
Therapists learned that the old adage, “seeing is believing,” often applies in seating and mobility clinics. IPM is an incredible and efficient teaching tool for practitioners, particularly when working with patients affected by new injuries and complete spinal cord injuries. The color-coded maps enable patients to visualize pressure, which is often a vague concept to them. Just one pressure mapping session can help patients understand the effects of poor posture, weight shifting, and other pressure-relief techniques.
For example, showing a patient how performing a few simple weight shifting maneuvers such as tilt-in-space, a forward lean, or a vertical push-up redistributes the pressure load and allows for increased blood flow, helps that “Aha!” moment to occur. Using IPM to visualize a patient’s pressure distribution before and after relief techniques are applied helps to actively engage them, and often helps reluctant patients or caregivers to understand the importance of reducing peak pressure and how these maneuvers can help.
Cushion/Seating Surface Selection
There are a variety of cushioning materials that all affect stability, pressure distribution, and interface temperature, among other factors, differently for individuals (See Figure 1). Wheelchair seat cushion selection is where IPM arguably provides the greatest value to SMS practitioners. In addition to providing optimal skin protection, a good cushion must enable optimal pelvic position, be clinically safe, functional, comfortable, and easy to use.
As with most things in the clinical setting, each patient has specific individual needs. There is no “one-size-fits-all” for seat cushion selection, and several key factors merit close consideration when selecting wheelchair cushions:
- Fixed versus flexible deformities;
- Presence of sensation or pain;
- Ability to perform weight shifts;
- Heat and moisture factors;
- Availability of power tilt-in-space;
- Current or past history of skin breakdown;
- Activity level; and
- Caregiver skill.
IPM augments seating evaluations, allowing clinicians to compare different seating surfaces and enabling them to make a more informed decision.
While IPM provides great value in various clinical applications, it is important for clinicians to note that it is just one of the many tools in their arsenal, and to be aware of its limitations. Pressure maps provide one-dimensional data that does not account for other key factors that can impact the patient’s skin integrity, such as shear, heat and moisture, use of power seating functions, activity level and functional mobility, and lifestyle. Furthermore, pressure maps are always relative to the individual patient or cushion assessed, and cannot be generalized for other patients or cushions.
Evolution of Pressure Mapping
Wheelchair seating and mobility is a dynamic space that has evolved in response to research, user frustration with the loss of functional mobility during pressure ulcer treatment, changes in healthcare policy that penalize healthcare settings for onset of skin breakdown, and the economics of prevention as compared to the cost of pressure ulcer treatment.
Initially developed to measure force in dental occlusions and the feet, IPM technology has come a long way. Thanks to technological advances in IPM hardware and software, there are several IPM systems available to clinicians. Among the IPM products manufacturers currently offer are smart seat, bed, and foot smart fabric pressure mapping systems that use elastic sensor with USB electronics built in, and can connect with WiFi and Web browser interfaces. Likewise, low-profile pressure sensing mats can capture static and dynamic pressure measurement data, and other mat-based systems can be used to fit a wheelchair seat and back to provide an accurate view of pressure distribution. For ambulatory patients the market offers an in-shoe system that can analyze interaction between the foot and shoe to provide data about foot function.
Therapists are seeing some exciting and valuable new technologies emerge as the industry continues to innovate. Continuous bedside IPM systems, for example, can now be used seamlessly on any support surface and provide caregivers with a useful monitor to assess the effectiveness of repositioning patients off of pressure areas—a crucial component of providing better care toward minimizing the formation of pressure ulcers.
Room for Improvement
While these advances are exciting, there is still room for more progress in regard to technologies and protocol. One big technology advancement therapists would like to see is technology that allows clinicians to remotely track patients’ IPM readings, particularly in power wheelchairs. Far too many patients do not realize how vulnerable they are and are not committed to weight shifting. A tool that would enable therapists to remotely track a patient’s weight shifts would be invaluable.
Lastly, there is growing demand internationally for a standardized clinical guideline for IPM data interpretation. While there is a standard protocol for administering an IPM, there are none for how to interpret the data, which is just as critical of a concern, if not more so. Lack of a standardized IPM interpretation protocol limits the ability to compare clinical research findings across studies using IPM, thereby denying the seating and mobility community rich learnings that could help refine and maximize how IPM is utilized in practice. RM
Mary Ellen Buning, PhD, OTR/L, ATP, SMS, is an occupational therapist with 30 years of specialization in assistive technology. She was recruited to the University of Louisville in 2008 to develop an assistive technology service delivery program to serve patients and develop staff training at Frazier Rehab Institute and Neuroscience Institute. This program, the Assistive Technology Resource Center (ATRC), is also the clinical training site for the Rehabilitation Engineering and Assistive Technology program in development in the Bioengineering Department at the UofL’s Speed School of Engineering. Frazier has an active treatment program in Wheelchair Seating and Mobility; Alternative and Augmentative Communication; Adaptive Computer Access, and environmental control and modifications.
Robert M. Meehan, PT, ATP, SMS, is a licensed physical therapist and certified seating and mobility specialist in the state of Kentucky, and has been a licensed PT since 2000 and a certified assistive technology practitioner since 2005. He works full-time in the Frazier Rehab Assistive Technology Resource Center and evaluates clients for their seating and mobility needs. Meehan is a member of the Board of Directors for the Center for Accessible Living in Louisville, Ky. For more information, contact RehabEditor@allied360.com.