Assessing evidence supporting redistribution of pressure for pressure ulcer prevention: a review

Prevalence of Sensor Saturation in Wheelchair Seat Interface Pressure Mapping

Pressure mapping is a frequently used tool with great power to provide information about the forces between a patient and a wheelchair seat. One widely recognized limitation to this paradigm is the possibility of data loss due to sensor saturation. In this study, we seek to quantify and describe the saturation observed in the measurement of interface pressures of wheelchair users. We recorded approximately two minutes of interface pressure data from 22 elderly wheelchair users (11M/11F, 80 ± 10 years) and found that 4.7% of data frames had 1 saturated sensor, and 9.0% had more than one saturated sensor, for a total of 13.7% of all frames of data. Data from three of the 22 subjects (13.6%) were substantially affected by the persistent presence of saturated sensors. We conclude that for this population of elderly wheelchair users, sensor saturation may be a concern and should be factored properly into study design a priori.

The repositioning of hospitalized patients with reduced mobility: a prospective study

AIM

To determine the frequency of patient repositioning across three consecutive nursing shifts (day, evening and night) and to identify predictors of repositioning frequency.

BACKGROUND

Patient repositioning is a frequently implemented pressure injury prevention strategy. Yet, little is known about how often it should be implemented, or the frequency of movement among hospitalized patients with reduced mobility.

DESIGN

An observational prospective study.

METHODS

Chart audits were used to gather clinical and demographic data. Semi-structured observations were conducted every 30 minutes for a continuous 24-hour period. Observational data included the patient's body position, the frequency of repositioning, assistance require to reposition and the use of support surfaces.

RESULTS

Patients were repositioned frequently during the day and evening and least at night time. Elevation of the head of the bed (1-45°) was the most frequently adopted position. The independent predictors of repositioning frequency were age and gender, with older patients and males repositioned less frequently.

Effect of tilt and recline on ischial and coccygeal interface pressures in people with spinal cord injury

OBJECTIVE

Clinicians commonly recommend that power wheelchair users with spinal cord injury perform wheelchair tilt and recline maneuvers to redistribute seating loads away from the ischial tuberosities. However, ischial pressure reduction may be accompanied by coccygeal pressure increases. Although the coccyx is among the most common sites of pressure ulcers, few studies have reported coccygeal interface pressure. The purpose of this study was to investigate both ischial and coccygeal interface pressures in response to changes in wheelchair tilt and recline angles.

DESIGN

Thirteen power wheelchair users were recruited into this study. Six combinations of wheelchair tilt (15, 25, and 35 degrees) and recline (10 and 30 degrees, corresponding to traditional recline conventions of 100 and 120 degrees, respectively) angles were tested in random order. Each combination was tested with 5 mins of upright sitting, 5 mins of tilt and recline, as well as 5 mins of maximal pressure relief recovery. Peak pressure indices were calculated at the ischial and coccygeal sites.

RESULTS

Ischial pressures monotonically decreased in response to increasing combinations of tilt and recline. Increments of 15 degrees of tilt did not produce significant differences under either recline angle, whereas increments of 25 degrees of tilt produced significant differences under both recline angles. Coccygeal pressures increased in response to the four smallest (of six) combinations of tilt and recline, whereas they decreased in response to the largest two combinations.

CONCLUSIONS

Ischial pressures seemed to be redistributed to the coccyx in response to the four smallest angle combinations and redistributed to the back support in response to the two largest angle combinations. Future work should confirm this pressure redistribution to the back support and determine the back support locations of redistribution.

Identifying the right surface for the right patient at the right time: generation and content validation of an algorithm for support surface selection

Support surfaces are an integral component of pressure ulcer prevention and treatment, but there is insufficient evidence to guide clinical decision making in this area. In an effort to provide clinical guidance for selecting support surfaces based on individual patient needs, the Wound, Ostomy and Continence Nurses Society (WOCN®) set out to develop an evidence- and consensus-based algorithm. A Task Force of clinical experts was identified who: 1) reviewed the literature and identified evidence for support surface use in the prevention and treatment of pressure ulcers; 2) developed supporting statements for essential components for the algorithm, 3) developed a draft algorithm for support surface selection; and 4) determined its face validity. A consensus panel of 20 key opinion leaders was then convened that: 1.) reviewed the draft algorithm and supporting statements, 2.) reached consensus on statements lacking robust supporting evidence, 3.) modified the draft algorithm and evaluated its content validity. The Content Validity Index (CVI) for the algorithm was strong (0.95 out of 1.0) with an overall mean score of 3.72 (out of 1 to 4), suggesting that the steps were appropriate to the purpose of the algorithm. To our knowledge, this is the first evidence and consensus based algorithm for support surface selection that has undergone content validation.

Pressure Ulcer Risk Assessment and Prevention for the Family Physician

Pressure ulcers are common and result in serious medical complications, prolonged hospital stay and frequent readmissions. With a rapidly ageing population and increasing chronic disease burden in Singapore, the prevalence of pressure ulcers will increase further. Family physicians will encounter more pressure ulcers in their practices in the primary, intermediate and long term care settings. We conducted a comprehensive literature review on established evidence on pressure ulcer risk assessment and prevention, and also reviewed current hospital protocols in Singapore. We found that many studies on pressure ulcer risk assessment and prevention lacked methodological quality to provide robust evidence and conclusions. Consequently, many of the recommendations in major international guidelines and protocols of major hospitals in Singapore are based on a combination of best available evidence, best practices and consensus opinion. We provided a summary of key recommendations for family physicians, based on the Strength of Recommendation Taxonomy (SORT) framework. We also hope to stimulate interest in regular updates of local guidelines and major hospital protocols in Singapore to reflect the latest evidence based strategies on risk assessment and prevention of pressure ulcers.

Effects of wheelchair cushions and pressure relief maneuvers on ischial interface pressure and blood flow in people with spinal cord injury

OBJECTIVE

To investigate the effectiveness and interactions of 2 methods of pressure ulcer prevention, wheelchair cushions and pressure relief maneuvers, on interface pressure (IP) and blood flow of the buttocks.

DESIGN

Within-subject repeated measures.

SETTING

Rehabilitation center.

PARTICIPANTS

Wheelchair users with a spinal cord injury or disorder (N=17).

INTERVENTIONS

Participants performed 3 forward leans and 2 sideward leans with different degrees of lean while seated on each of 3 different wheelchair cushions.

MAIN OUTCOME MEASURES

IP measured with a custom sensor and blood flow measured with laser Doppler flowmetry were collected at the ischial tuberosity.

RESULTS

Pressure relief maneuvers had a significant main effect on the ischial IP (P<.001); all maneuvers except for the small frontward lean resulted in a significant reduction in IP compared with upright sitting. Blood flow significantly varied across postures (P<.001) with flow during upright sitting and small forward leans being significantly lower than during the full and intermediate leans in both the forward and sideward directions.

CONCLUSIONS

The results of the study highlight the importance of positioning wheelchair users in a manner that facilitates in-seat movement. Regardless of the cushion being used, the pressure relief maneuvers resulted in very large reductions in IPs and significant increases in buttock blood flow. Only the small frontward lean was shown to be ineffective in reducing pressure or increasing blood flow. Because these pressure relief maneuvers involved postural changes that can occur during functional activities, these pressure relief maneuvers can become a part of volitional pressure relief and functional weight shifts. Therefore, clinical instruction should cover both as a means to impart sitting behaviors that may lead to better tissue health.

Effect of interpolation on parameters extracted from seating interface pressure arrays

Interpolation is a common data processing step in the study of interface pressure data collected at the wheelchair seating interface. However, there has been no focused study on the effect of interpolation on features extracted from these pressure maps, nor on whether these parameters are sensitive to the manner in which the interpolation is implemented. Here, two different interpolation paradigms, bilinear versus bicubic spline, are tested for their influence on parameters extracted from pressure array data and compared against a conventional low-pass filtering operation. Additionally, analysis of the effect of tandem filtering and interpolation, as well as the interpolation degree (interpolating to 2, 4, and 8 times sampling density), was undertaken. The following recommendations are made regarding approaches that minimized distortion of features extracted from the pressure maps: (1) filter prior to interpolate (strong effect); (2) use of cubic interpolation versus linear (slight effect); and (3) nominal difference between interpolation orders of 2, 4, and 8 times (negligible effect). We invite other investigators to perform similar benchmark analyses on their own data in the interest of establishing a community consensus of best practices in pressure array data processing.

Seat pressure changes after eight weeks of functional electrical stimulation cycling: a pilot study

BACKGROUND

Pressure ulcers (PUs) are a common secondary condition associated with spinal cord injury (SCI). PUs can potentially interfere with activities of daily living, occupational duties, and rehabilitation programs, and in severe cases they may threaten life. Functional electrical stimulation (FES) cycling has been proposed as an activity that may decrease the risk of PUs through the promotion of increased blood flow and thickening of the gluteus maximus. The purpose of this pilot study was to measure the effects of home-based FES cycling on the average and maximal seat pressure of wheelchair-reliant individuals with SCI.

METHOD

Eight male veterans with C5-T6 SCI participated in FES cycling 3 times per week. Cycling parameters were individualized depending on the comfort of the participants and the amount of current needed to perform the cycling activity. Pressure mapping was completed immediately before and after the 8 weeks of FES cycling with the measurement performed by a force sensitive application (FSA) 4 pressure mapping system.

RESULTS

The mean average seat pressure decreased by 3.69 ± 4.46 mm Hg (35.57 ± 11.99 to 31.88 ± 13.02), while the mean maximum seat pressure decreased by 14.56 ±18.45 mm Hg (112 ± 34.73 to 98.36 ± 25.89). Although neither measurement was statistically significant, there was a strong trend toward a reduction in average and maximal seat pressure (P = .052 and P = .061, respectively).

CONCLUSION

The positive trend of decreased seat pressure in our study creates incentive for further investigation of the effects of electrical stimulation activities on seat pressure and the prevention of PUs.

Spinal cord injury and pressure ulcer prevention: using functional activity in pressure relief

Background. People with spinal cord injury (SCI) are at increased risk of pressure ulcers due to prolonged periods of sitting. Concordance with pressure relieving movements is poor amongst this population, and one potential alternative to improve this would be to integrate pressure relieving movements into everyday functional activities. Objectives. To investigate both the current pressure relieving behaviours of SCI individuals during computer use and the application of an ergonomically adapted computer-based activity to reduce interface pressure. Design. Observational and repeated measures design. Setting. Regional Spinal Cord Injury Unit. Participants. Fourteen subjects diagnosed with SCI (12 male, 2 female). Intervention.Comparing normal sitting to seated movements and induced forward reaching positions. Main Outcome Measures. Interface pressure measurements: dispersion index (DI), peak pressure index (PPI), and total contact area (CA). The angle of trunk tilt was also measured. Results. The majority of movements yielded less than 25% reduction in interface pressure compared to normal sitting. Reaching forward by 150% of arm length during an adapted computer activity significantly reduced DI (P < 0.05), angle of trunk tilt (p<0.05), and PPI for both ischial tuberosity regions (P < 0.001) compared to normal sitting. Conclusion. Reaching forward significantly redistributed pressure at the seating interface, as evidenced by the change in interface pressures compared to upright sitting.

Comparison of muscle and skin perfusion over the ischial tuberosities in response to wheelchair tilt-in-space and recline angles in people with spinal cord injury

OBJECTIVE

To compare the efficacy of wheelchair tilt-in-space and recline on enhancing muscle and skin perfusion over the ischial tuberosities in people with spinal cord injury (SCI).

DESIGN

Repeated-measures and before-after trial design.

SETTING

University research laboratory.

PARTICIPANTS

Power wheelchair users with SCI (N=20).

INTERVENTIONS

Six combinations of wheelchair tilt-in-space and recline angles were presented to participants in a random order. The testing protocol consisted of a baseline 5 minutes sitting with no tilt/recline and 5 minutes positioned in a tilted and reclined position at each of 6 conditions, including: (1) 15° tilt-in-space and 100° recline, (2) 25° tilt-in-space and 100° recline, (3) 35° tilt-in-space and 100° recline, (4) 15° tilt-in-space and 120° recline, (5) 25° tilt-in-space and 120° recline, and (6) 35° tilt-in-space and 120° recline.

MAIN OUTCOME MEASURES

Muscle and skin perfusion were assessed by near-infrared spectroscopy and laser Doppler flowmetry, respectively.

RESULTS

Muscle perfusion was significantly increased at 25° and 35° tilt-in-space when combined with 120° recline, and skin perfusion was significantly increased at 3 tilt-in-space angles (15°, 25°, 35°) when combined with 120° recline and at 35° tilt-in-space when combined with 100° recline (P<.05). Even in the positions of increased muscle perfusion and skin perfusion (25° and 35° of tilt-in-space combined with 120° of recline), the amount of muscle perfusion change was significantly lower than the amount of skin perfusion change (P<.05).

CONCLUSIONS

Our results indicate that a larger angle of tilt-in-space and recline is needed to improve muscle perfusion compared with skin perfusion. A position of 25° tilt-in-space combined with 120° recline is effective in enhancing muscle and skin perfusion of weight-bearing soft tissues at the ischial tuberosities.

A Literature Review of Pressure Ulcer Prevention: Weight Shift Activity, Cost of Pressure Care and Role of the Occupational Therapist

Introduction:

Pressure ulcers are a major concern for those who spend a prolonged period of time sitting. Weight shifts are one prevention strategy used to reduce the risk of tissue damage. Currently, the prevalence of pressure ulcers is high, suggesting that concordance with preventative methods is poor. Occupational therapy focuses on the use of functional activity to promote health and wellbeing. The aim of this literature review was to evaluate the role of functional activity in reducing seated interface pressure.

Method:

A comprehensive search of nine electronic databases (AMED, CINAHL, Ovid MEDLINE, SportDiscus, EMBASE, British Nursing Index, Cochrane Library, Google Scholar and OTDBASE) was conducted between January 2000 and October 2011.

Findings:

From the 24 articles included in the review, there is limited evidence evaluating the role of functional activity and weight shifts in reducing seated interface pressure. Limited evidence suggests poor concordance with weight shifts, with wheelchair users repositioning on average once every 1–2 hours. The cost of pressure ulcer care is considerable, with an average annual cost of £1.7 billion in the United Kingdom. Occupational therapists have a key preventative role.

Conclusion:

Further research is needed to explore the role of functional activity and to determine the effectiveness of weight shift activity in reducing seated interface pressure.

Reviewing the literature on the effectiveness of pressure relieving movements

Sitting for prolonged periods of time increases seating interface pressures, which is known to increase the risk of developing pressure ulcers. Those at risk of developing pressure ulcers are advised to perform pressure relieving movements such as "pushups" or "forward leans" in order to reduce the duration and magnitude of pressure acting on the vulnerable ischial tuberosity region. The aim of this review was to synthesize and critique the existing literature investigating the effectiveness of pressure relieving movements on seating interface pressures. The twenty-seven articles included in this paper highlight the need for further research investigating the effect of recommended pressure relieving movements on the pressures around the ischial tuberosities. Furthermore, this review found that the majority of individuals at risk of developing pressure ulcers do not adhere with the pressure relieving frequency or magnitude of movements currently recommended, indicating a need for pressure ulcer prevention to be explored further.

The effect of a trunk release maneuver on Peak Pressure Index, trunk displacement and perceived discomfort in older adults seated in a High Fowler's position: a randomized controlled trial

Background

Pressure ulcers pose significant negative individual consequences and financial burden on the healthcare system. Prolonged sitting in High Fowler’s position (HF) is common clinical practice for older adults who spend extended periods of time in bed. While HF aids in digestion and respiration, being placed in a HF may increase perceived discomfort and risk of pressure ulcers due to increased pressure magnitude at the sacral and gluteal regions. It is likely that shearing forces could also contribute to risk of pressure ulcers in HF. The purpose of this study was to evaluate the effect of a low-tech and time-efficient Trunk Release Manuever (TRM) on sacral and gluteal pressure, trunk displacement and perceived discomfort in ambulatory older adults.

Method

A randomized controlled trial was used. We recruited community-living adults who were 60 years of age and older using posters, newspaper advertisements and word-of-mouth. Participants were randomly allocated to either the intervention or control group. The intervention group (n = 59) received the TRM, while the control group (n = 58) maintained the standard HF position.

Results

The TRM group had significantly lower mean (SD) PPI values post-intervention compared to the control group, 59.6 (30.7) mmHg and 79.9 (36.5) mmHg respectively (p = 0.002). There was also a significant difference in trunk displacement between the TRM and control groups, +3.2 mm and −5.8 mm respectively (p = 0.005). There were no significant differences in perceived discomfort between the groups.

Conclusion

The TRM was effective for reducing pressure in the sacral and gluteal regions and for releasing the trunk at the point of contact between the skin and the support surface, but did not have an effect on perceived discomfort. The TRM is a simple method of repositioning which may have important clinical application for the prevention of pressure ulcers that may occur as a result of HF.

Clinical assessment, design and performance testing of mobile shower commodes for adults with spinal cord injury: an exploratory review

PURPOSE

The purpose of this article is to explore evidence concerning clinical assessment, design and performance testing of mobile shower commodes used by adults with spinal cord injury (SCI).

METHOD

Searches of electronic databases, conference proceedings and key journals were undertaken with no restriction on language or study design. Keywords included spinal cord injury, lesion, sanichair, sanitary chair, shower chair, bowel chair and commode.

RESULTS

A total of 20 publications were included in this review. Common approaches to clinical assessments were questionnaires and observational analysis to assess bowel care routines, function and skin integrity. Design features addressed access for bowel care, postural support, transfers, stability, use in wet environments and skin integrity. Objective performance measures addressed requirements for static stability, backward-sloping seat angles, arm supports and seat materials.

CONCLUSIONS

Evidence reviewed was of low methodological quality and lacking in validated instruments to guide clinical practice. Further high-quality research is needed to identify bathing, showering and personal hygiene tasks affecting mobile shower commodes use and to develop validated clinical assessment tools. Performance testing to published standards is also needed.