Pressure mapping: A new path to pressure-ulcer prevention

By: Darlene Hanson, MS, RN, Pat Thompson, MS, RN, Diane Langemo, PhD, RN, FAAN,  Susan Hunter, MS, RN, and Julie Anderson, PhD, RN, CCRC

Faced with the nursing diagnosis of Impaired skin integrity, we’ve all written care plans that state our goal as “redistributing or reducing pressure.” But how do we do that? Which measures do we take? And how do we know that our interventions have relieved pressure? Do we rely solely on a skin assessment? A patient’s self-assessment of comfort? What if the patient can’t feel pressure relief because of neurologic impairment?

The answers to these questions may be that nurses should use pressure mapping, a tool used by occupational and physical therapists to determine seat-interface pressures and by other healthcare professionals to perform foot assessments.

What is pressure mapping?

A pressure map is a computerized clinical tool for assessing pressure distribution. To use it, you place a thin, sensor mat on a wheelchair seat or a mattress surface. When your patient sits or lies on the mat, a computer screen displays a map of pressures, using colors, numbers, and a graphic image of the patient. (See A look at pressure maps by clicking the PDF icon above.) Typically, the hotter colors (the reds) indicate areas of higher pressures, and the cooler colors (the blues) indicate areas of lower pressures. The display usually has several options, including a three-dimensional display of peak pressure areas and a statistical analysis.

Pressure mapping does have some drawbacks, including inconsistencies in the ways manufacturers report and display the pressures, differences in measurable peak pressures among manufacturers, and sensor accuracy and drift. Still, these visual displays provide key data that can augment nursing assessment of the areas of potential tissue damage. Plus, patients can benefit from the visual feedback. When they see the pressures on the screen, they can identify areas of concern and modify their position accordingly. There is also an economic benefit because Medicare and many insurance companies do not reimburse for the extra costs of treating preventable conditions, including pressure ulcers.

Pressure-mapping successes

Research has shown that pressure mapping is a reliable means of assessment, but more research is needed to determine its ability to predict pressure-ulcer development. Here are short summaries of recent research.

•    In 2005, occupational therapists used pressure mapping to assess the wheelchair cushions of 40 patients and found that 19 of them should have been using a different seating surface.
•    A 2006 study used pressure mapping to assess seated postural control in children and found the tool useful in evaluating seating stability.
•    Using pressure-mapping technology, researchers found that elevating a wheelchair-bound patient’s feet and reclining his wheelchair by 30 degrees reduced interface pressure and the risk of
pressure-ulcer development.
•    While researchers have used pressure mapping to test wheelchair surfaces, wheelchair positioning, and client angles in wheelchairs in the past several years, few studies have looked at pressure mapping in bedbound individuals. In one study where researchers used pressure mapping on a bed surface, the authors recommended that pressure mapping be used in combination with other measures such as transcutaneous oxygen measurements. Both measures can provide useful biofeedback to help determine the efficacy of pressure-relief strategies.
•    In 2012, Kim, Wang, Ho, & Bogie, who used pressure mapping in combination with transcutaneous oxygen readings, surmised that healthy individuals adapt to pressure load because they have adaptive blood flow that compensates for the increased pressure, unlike some individuals, who are at higher risk for developing pressure ulcers because they lack adaptive blood flow. To date, it has not been determined who adapts to pressure and who doesn’t, so it’s still a good idea to reduce pressure load for patients.
•    Researchers in a 2009 study used pressure mapping to determine how often individuals shift their posture, and found that nondisabled subjects change their posture about 7.8 times an hour to relieve subcutaneous tissue pressures. These researchers recommended that wheelchair-bound individuals shift their posture at least every 8 minutes to maintain tissue viability.
•    A 2010 study that used pressure mapping to determine differences between spine boards found that when comparing rigid and soft spine boards and vacuum mattresses, lower tissue interface pressures were associated with less discomfort.
•    Researchers have used pressure-mapping technology to find that a minimum tilt angle of 30 degrees is required to alleviate pressure at the ischial tuberosities and sacrum for wheelchair-seated individuals with motor complete spinal cord injury.
•    A 2006 study by Turpin and other researchers recommended that, based on pressure-mapping analysis, turning was not needed for patients on a continuous lateral turning bed. Since that time, controversy has arisen, suggesting that caution is required when recommending that turning isn’t needed for patients on specialty beds. In 2007, Pompeo advocated that patients on turning beds should continue to be turned, arguing that “no pressure” is always better than “low pressure,” and that caregivers should always visually check patients with every turn, looking for incontinence and evidence of skin breakdown.

Assessment and repositioning

Current guidelines on assessment and repositioning come from several sources.
A report called “Best Practice Recommenda­tions for the Prevention and Treatment of Pressure Ulcers: Update 2006” says that pressure should be assessed on all surfaces a patient comes in contact with and notes that computerized pressure mapping is one way to assess those surfaces.

Other guidelines on pressure reduction come from the National Collaborating Centre for Nursing and Supportive Care in the United Kingdom. These guidelines recommend assessing a patient’s support surfaces and positioning needs on a regular basis. One key point in several guidelines is that patients need repositioning, regardless of the bed or seating surface. No bed or seating surface replaces repositioning.

Repositioning frequency should be determined by the individual’s tissue tolerance, level of activity and mobility, and general medical condition, as well as the overall treatment objectives, support surface in use, and assessments of the individual’s skin condition.

Using pressure mapping

For now, universal, evidence-based guidelines for pressure mapping don’t exist. More research on and experience with pressure mapping is needed. But you should be aware of typical manufacturer’s recommendations, which the pressure-mapping clinician will follow. (See Guide­lines for pressure-mapping sessions by clicking the PDF icon above.)

Be prepared for a session that may take 30 minutes or more. A 2005 study found that interface pressures in wheelchair users continued to fluctuate for up to 8 minutes after the patients were seated. So obtaining good pressure readings may take some time.

Before the procedure, tell the patient how long the pressure-mapping session will take. Explain that he will be able to view the results on a computer screen. During the procedure, you may be asked to help the pressure-mapping clinician with the necessary positioning. Be sure to explain the test and the results to your patient. After the session, follow up by answering any patient questions and carefully documenting the session.

Information from a pressure-mapping session may lead to immediate changes in the patient’s activity level as well as his bed or wheelchair surface. For example, if the results of the session indicate that a new cushion must be ordered, the patient may be confined to bed while waiting for it.

Benefits of mapping

Pressure mapping can provide you with valuable, visual information that augments your assessment of the patient’s skin and the potential for skin breakdown, sparing your patient from the complications of pressure ulcers.

If you don’t have access to pressure mapping equipment where you work, see More measures to check for pressure.

Selected references

Crawford SA, Stinson MD, Walsh DM, Porter-Armstrong AP. Impact of sitting time on seat-interface pressure and on pressure mapping with multiple sclerosis patients. Arch Phys Med Rehabil. 2005;86:1221-1225.

Crawford SA, Strain B, Gregg B, Walsh DM, Porter-Armstrong AP. An investigation of the impact of the Force Sensing Array pressure mapping system on the clinical judgment of occupational therapists. Clin Rehabil. 2005;19(2):224-231.

European Pressure Ulcer Advisory Panel and National Pressure Ulcer Advisory Panel. Prevention and treatment of pressure ulcers: quick reference guide. Washington DC: National Pressure Ulcer Advisory Panel; 2009.

Glesbrecht EM, Ethans KD, Staley D. Measuring the effect of incremental angles of wheelchair tilt on interface pressure among individuals with spinal cord injury. Spinal Cord. 2011;49(7):827-831.

Hemmes B, Poeze M, Brink PR. Reduced tissue-interface pressure and increased comfort on a newly developed soft-layered long spineboard. J Trauma. 2010;68(3):593-598.

Keast DH, Parslow N, Houghton PE, Norton L, Fraser C. Best practice recommendations for the prevention and treatment of pressure ulcers: update 2006. Wound Care Canada. 2006;4(1):31-43.

Kim J, Wang X, Ho C, Bogie K. Physiological measurements of tissue health: implications for clinical practice. Int Wound J. January 30, 2012. doi:10.1111/j.1742-481X.2011.00935.x.

LaCoste M, Therrien M, Cote J, Shrier I, Labelle H, Prince F. Assessment of seated postural control in children: comparison of a force platform versus a pressure mapping system. Arch Phys Med Rehabil. 2006;87:1623-1629.

National Collaborating Centre for Nursing and Supportive Care. Pressure ulcer prevention. Pressure ulcer risk assessment and prevention, including the use of pressure-relieving devices (beds, mattresses and overlays) for the prevention of pressure ulcers in primary and secondary care. London: National Institute for Clinical Excellence; 2003.

National Pressure Ulcer Advisory Panel Support Surface Standards Initiative. Terms and definitions related to support surfaces. 2007. www.npuap.org/NPUAP_S3I_TD.pdf. Accessed March 14, 2012.

Pompeo M. Pressure mapping. J Wound Ostomy Continence Nurs. 2007;34(1):33.

Reenalda J, Van Geffen P, Nederhand M, Jannink M, Ijzerman M, Rietman H. Analysis of healthy sitting behavior: interface pressure distribution and subcutaneous tissue oxygenation. J Rehabil Res Develop. 2009;46:577-586.

Stinson, MD, Porter-Armstrong A, Eakin PA. Pressure mapping systems: reliability of pressure map interpretation. Clin Rehabil. 2003;17(5):504-511.

Stinson MD, Porter-Armstrong A, Eakin P. Seat interface pressure: a pilot study of the relationship to gender, body mass index, and seating position. Arch Phys Med Rehabil. 2003;84(3):405-409.

Turpin PG, Pemberton V. Prevention of pressure ulcers in patients being managed on CLRT: is supplemental repositioning needed? J Wound Ostomy Continence Nurs. 2006;33(4):381-388.

Urasaki M, Nakagami G, Sanada H, Kitagawa A, Sugama J. Interface pressure distribution of elderly Japanese people in the sitting position. Disabil Rehabil Assist Technol. 2011;6(1):38-46.

Vista Medical. www.pressuremapping.com. Accessed March 14, 2012.

Wound, Ostomy and Continence Nurses Society. Guidelines for Prevention and Management of Pressure Ulcers. Glenview, IL: Wound, Ostomy and Continence Nurses Society; 2003.

Darlene Hanson is a Clinical Associate Professor, Pat Thompson is a Clinical Assistant Professor, Diane Langemo is Chester Fritz Distinguished Professor Emeritus and Adjunct Professor, Susan Hunter is an Associate Professor, and Julie Anderson is an Associate Professor. All teach at University of North Dakota, College of Nursing in Grand Forks.