An Investigation of Pressure Ulcer Risk,Comfort, and Pain in Medical Imaging

Introduction

Pressure ulcers present significant trauma to patients and are expensive to manage. In medical imaging (MI), no study has been conducted to rigorously investigate interface pressure (IP) risk on MI table surfaces. IP is defined as the pressure between human body and a supporting surface. The aims of this research were to investigate whether IP risks exist on MI table surfaces and to assess pain and comfort when lying on MI table surfaces.

Preventing pressure ulcers: an evaluation of four operating-table mattresses.

Pressure is a major factor in the development of pressure ulcers. This research focused on assessing the pressure-reducing effects of operating-table mattresses. Five mattresses were tested: a standard operating-table mattress, a foam mattress, a gel mattress, a visco-elastic polyether mattress, and a visco-elastic polyurethane mattress. Four intraoperative postures were evaluated: supine, lateral, fossa, and the Miles-Pauchet position. Interface pressure measurements were performed on 36 healthy volunteers. The foam mattress and the gel mattress seem to have little or no pressure-reducing effect; the polyurethane mattress and the polyether mattress reduce interface pressure significantly better (p < .001); but none of the mattresses reduce pressure sufficiently to prevent the occurrence of pressure ulcers.     

MEASUREMENTS OF INTERFACE PRESSURE BETWEEN BODY SITES AND THE SURFACES OF FOUR SPECIALISED AIR MATTRESSES

SUMMARY Four specialised air mattresses had interface pressure measured under six body sites prone to pressure sores in 10 subjects, supine and sitting. The mattresses were the Clinirest (SSI) and FirstStep (KCI) continuous airflow mattress overlays, and Airwave (Pegasus) and Nimbus (Huntleigh) alternating pressure air mattresses. On the mattress overlays, average supine interface pressures were 2.33 kPa (scapula), 4.15 kPa (elbow), 1.94 kPa (sacrum) and 2.79 kPa (buttock), although they were higher at the occiput (7.97 kPa) and heel (11.7 kPa). The alternating pressure air mattresses had an average minimum interface pressure close to zero for three sites, rising to 4.28 kPa under the heel. Average maximum interface pressures were 8.61 kPa (occiput), 5.21 kPa (scapula), 4.90 (elbow), 4.85 kPa (sacrum), 4.61 kPa (buttock) and 13.2 kPa (heel). No accepted scientific method exists for comparing the two types of mattress. Our data suggest a clinical benefit at the occiput and heel (supine) in using an alternating pressure air mattress and a benefit in using a continuous airflow mattress overlay at other sites.     

Effects of different heel angles in sleep mode on heel interface pressure in the elderly

BackgroundThe heels are one of the most common sites of pressure ulcers, and the incidence rate in the elderly aged 70 years or older is high. Although there is literature on heel interface pressure, the heel interface pressure of the elderly in different postures has not yet been explored, which will be investigated in this study, as well as the effects of different foot positions. Their skin conditions will also be examined.MethodsTwenty-five females and twenty-six males, 70 years old or older, are evaluated while lying down, with only their naked foot in its natural position on a mattress, as well as placed on a standard or pressure-relieving mattress in different positions. The moisture, sebum content, and elasticity of the skin of the heel are tested.FindingsThe heel of most of the participants is positioned at a 60°–69° or 90°–99° angle to the support surface. The heel interface pressure is the greatest when the foot is upright. The age, weight, and body mass index have no significant impacts. The moisture and sebum content are extremely low while elasticity is normal.InterpretationThe relaxed position of the foot is in neutral external rotation and upright positions. A greater amount of pressure is experienced when the foot is upright. The pressure-relieving mattress is more effective for reducing heel pressure but may not apply to all cases. Finally, the skin of the heel is dry and lacks sebum, which implies greater risk of developing heel sores.     

The impact of compliant surfaces on in-hospital chest compressions: Effects of common mattresses and a backboard

PurposeTo evaluate, in a hospital setting, the influence of different, common mattresses, with and without a backboard, on chest movement during CPR.Design and settingSixty CPR sessions (140 s each, 30:2, C:R ratio 1:1) were performed using a manikin on standard hospital mattresses, with or without a backboard in combination with variable weights. Sternum-to-spine compression distance was controlled (range 30–60 mm) allowing evaluation of the underlying compliant surface on total hand travel.ResultsMovement of the caregiver's hands was significantly larger (up to 111 mm at 50 mm compression depth, p < 0.0001) when sternum-to-spine compressions were performed without a backboard than with one. The extent of this variable extra travel effect depended on the type of mattress as well as the force of compression. Foam mattresses and air chamber systems act as springs and follow hand movement, while ‘slow foam’ mattresses incorporate time delays, making depth and force sensing harder. A backboard decreases the extra hand movement due to mattress effects by more than 50%, strongly reducing caregiver work.ConclusionsTotal vertical hand movement is significantly, and clinically relevantly, much larger than sternum-to-spine compression depth when CPR is performed on a mattress. Additional movement depends on the type of mattress and can be strongly reduced, but not eliminated, when a backboard is applied. The additional motion and increased work load adds extra complexity to in-hospital CPR. We propose that this should be taken into account during training by in-hospital caregivers.     

Mattress Coil Spring Fatigue and Weight-Bearing Support: Comparison of Weight-Bearing and Non–Weight-Bearing Springs

ObjectiveThe purpose of this study was to compare the firmness of used mattress coil springs from the areas bearing greatest body weight versus areas subjected to little compression.MethodsWeight-bearing springs (WBS) extracted from the center of the mattresses (N = 32), and non–weight-bearing springs (NWBS) extracted from the head/foot were of the same mattresses. To determine spring weakness, a 1296-g ingot was placed on the coil, and the compression distance was measured (cm). In addition, a gauge was used to measure the amount of pressure required to compress the coil springs a distance of 2 cm. Comparison between WBS and NWBS data were statistically treated using independent t tests and a 1-way analysis of variance.ResultsThere were no significant group differences in weight or height in unloaded coils. However, there were significant (P < .05) differences in coil spring compression distance under load (WBS = 2.78 ± 0.34 cm; NWBS = 1.52 ± 0.39 cm) and force gauge compression (WBS = 1090.51 ± 88.42 g; NWBS = 1213.12 ± 71.38 g) between groups.ConclusionThis study found that WBSs were weaker when compressed than the NWBS from used mattresses, and such characteristics may not be visually apparent in a mattress when not in use. Thus, coil springs in bedding systems may eventually fail to provide the initial structural support after use. Such sagging may compromise sleep posture with accompanying poor sleep quality and quantity.     

Forensic analysis of crib mattress properties on pediatric CPR quality—Can we balance pressure reduction with CPR effectiveness?

Introduction

Single mode, pressure reduction (PR) crib mattresses are increasingly employed in hospitals to prevent skin injury and infection. However, single mode PR mattresses risk large mattress deflection during CPR chest compressions, potentially leading to inadequate chest compressions.

Hypothesis

New, dual mode PR crib mattress technology provides less mattress deflection during chest compressions (CCs) with similar PR characteristics for prevention of skin injury.

Methods

Epochs of 50 high-quality CCs (target sternum–spine compression depth ≥38 mm) guided by real-time force/deflection sensor (FDS) feedback were delivered to CPR manikin with realistic CC characteristics on two PR crib mattresses for four conditions: (1) single mode + backboard; (2) dual mode + backboard; (3) single mode − no backboard; and (4) dual mode − no backboard. Mattress displacement was measured using surface reference accelerometers. Mattress displacement ≥5 mm was prospectively defined as minimal clinically important difference. PR qualities of both mattresses were assessed by tissue interface pressure mapping.

Results

During simulated high quality CC, single mode had significantly more mattress displacement compared to dual mode (mean difference 16.5 ± 1.4 mm, p < 0.0001) with backboard. This difference was greater when no backboard was used (mean difference 31.7 ± 1.5 mm, p < 0.0001). Both single mode and dual mode met PR industry guidelines (mean surface pressure <50 mmHg).

Conclusions

Chest compressions delivered on dual mode pressure reduction crib mattresses resulted in substantially smaller mattress deflection compared to single mode pressure reduction mattresses. Skin pressure reduction qualities of dual mode pressure reduction crib mattress were maintained. We recommend that backboards continue to be used in order to mitigate mattress deflection during CPR on soft mattresses.     

Effects of absorbent incontinence pads on pressure management mattresses

AIM: The aim of this paper is to report a study to determine the effects of absorbent pads on the pressure-relieving properties of 'standard' and pressure management mattresses. BACKGROUND: Pressure ulcers and incontinence often co-exist. There is a strong association between poor mobility and continence problems and patients using pressure management products are therefore also likely to be using absorbent pads. METHODS: An instrumented articulated anthropometric phantom with simulated soft body 'tissues' in the gluteal and sacral areas was used as the 'subject'. The phantom was raised and lowered on to three mattresses (standard foam, visco-elastic foam and surface-cut foam) in three states: naked, wearing a dry pad (Tena Super, SCA Hygiene AB) and wearing a wet pad. The pressure mapping device Xsensor was used to record the distribution of pressure over the sacral and ischial areas of the phantom. Peak pressure was used as the primary outcome variable and 10 repeats were made on each mattress under each condition. RESULTS: There were substantial and significant differences for all three mattresses in recorded peak pressures between the naked buttocks and the buttocks wearing a dry pad. There were no significant differences between measurements made using the dry vs. wet pad. Peak pressures frequently occurred over areas of pad folds. Additional testing showed that pads that were 'smoothed' by hand had significantly lower peak pressures than 'unsmoothed' pads. CONCLUSIONS: Absorbent pads have a substantial adverse effect on the pressure redistribution properties of mattresses. Pad folds appear to contribute to this effect, which can be ameliorated slightly by smoothing. Absorbent pad manufacturers should consider engineering pads that minimize disruption to pressure management. Further examination of continence and pressure management products is necessary to establish optimum combinations for nursing care.     

Microstructural characteristics of human skin subjected to static versus cyclic pressures.

Pressure ulcers are generally associated with external pressures exceeding internal capillary pressures over bony prominences when the body cannot initiate motor movement to change positions. This investigation evaluated microstructural changes occurring in human skin, in vitro, exposed to static versus cyclic pressures, simulating those recorded for heels of human subjects on various pressure-relief mattresses. Morphological data are reported for tissues exposed to pressure in a bench-scale loading system. Dynamic (cyclic-relief) pressure induced parallel alignments of connective tissue collagen bundles, which themselves became differentially oriented to various degrees perpendicular to the surface of the tissue. Static pressure, with no relief, invariably produced alignment of the collagen bundles of the connective tissue parallel to both one another and to the compressed tissue surface. The precursor to pressure ulcer formation may be microstructural alignment in response to the pressure conditions on tissue.     

Intraoperative pressure sore prevention: An analysis of bedding materials

The relationship between operating room (OR) table surfaces and skin integrity was examined. Preoperatively, patients (N = 505) were rated for pressure sore potential (Hemphill); postoperatively, skin condition was assessed. Skin changes were more likely with a standard mattress only or with surgery longer than 2.5 hr. The overlay was more effective than the foam and gel or standard foam mattresses for preventing pressure sore formation. Factors predictive of pressure sore development included surgery of 2.5+ hr, 40+ years, vascular disease, and a preoperative Hemphill value of 4+. Patient characteristics, surgical experience variables, and OR table surfaces are determinants in pressure sore development.     

Comparison of a long spinal board and vacuum mattress for spinal immobilisation

Methods: Nine volunteers wearing standardised clothing and rigid neck collars were secured on to a backboard and vacuum mattress using a standard strapping arrangement. An operating department table was used to tilt the volunteers from 45 degrees head up to 45 degrees head down, and additionally 45 degrees laterally. Movements of the head, sternum, and pubic symphysis (pelvis) from a fixed position were then recorded. The comfort level during the procedure was assessed using a 10 point numerical rating scale (NRS) where 1=no pain and 10=worst pain imaginable.

Results: The mean body movements in the head up position (23.3 v 6.66 mm), head down (40.89 v 8.33mm), and lateral tilt (18.33 v 4.26mm) were significantly greater on the backboard than on the vacuum mattress (p<0.01 for all planes of movement). Using the NRS the vacuum mattress (mean score=1.88) was significantly more comfortable than the backboard (mean score=5.22) (p<0.01).

Conclusions: In the measured planes the vacuum mattress provides significantly superior stability and comfort than a backboard.

     

Interface pressure comparison of healthy premature infants with various neonatal bed surfaces

PURPOSE: The aim of this study was to determine interface pressure between the occiput of healthy premature infants and 5 different bed surfaces used in special care nurseries. SUBJECTS: Thirteen healthy premature infants comprised the convenience sample enrolled 1 to 3 weeks prior to discharge. DESIGN: A quasi-experimental design was used with the dependent variable being the interface pressures obtained under the occiput and the independent variables as the bed surfaces. METHODS: Order of bed surfaces was randomized and standardization of the infant positioning and measuring procedure maintained. Measurements were made between the infant's occiput and the bed surface and interface pressures recorded in millimeters of mercury. The 5 bed surfaces were standard crib mattress with or without foam, gel donut, gel mattress, and water pillow. MEASURES: Interface pressure measurements were obtained using the Mini-Texas Interface Pressure Evaluator (Mini-TIPE, Tee-Kay Applied Technology, Inc, Stafford, Texas). RESULTS: A 1-way blocked analysis of variance was conducted to evaluate the relationship between the mattress surfaces and the interface pressure measurements. A significant difference in the mean of the interface pressures among the 5 mattress bed surfaces was determined, F(4,46) = 33.267, P < .001, with the lowest being the foam overlay. The standard crib mattress had the highest interface pressure that exceeded 100 mm Hg. Post hoc comparisons showed a significant difference between the standard crib mattress with and without foam and the other surfaces. CONCLUSIONS: Interface pressure is an important consideration when choosing a support surface for premature infants susceptible to tissue compromise and head molding. Variations in interface pressures between neonatal bed surfaces are apparent. Comparison studies of interface pressures using these and other neonatal bed surfaces will be valuable in determining appropriate products for both premature and neonatal populations with lengthy intensive care stays.     

A 4-cm thermoactive viscoelastic foam pad on the operating room table to prevent pressure ulcer during cardiac surgery

Aims and objectives. In this experimental study, a 4‐cm thermoactive viscoelastic foam overlay and a heating source on the operating room table was compared with the standard operating room table with a heating source for the effect on the postoperative pressure ulcer incidence in cardiac surgery patients. Background. Pressure ulcer incidence in the cardiac surgery population is reported to be up to 29·5%. The prolonged compressive forces from lying on the operating room table are one source of pressure ulcer development in this population. Pressure‐reducing devices on the operating room (OR)‐table should reduce the patients’ interface pressure and thus the hazard of skin breakdown. Methods. A randomized controlled trial was performed to test the effect of a 4‐cm thermoactive viscoelastic foam overlay with a water‐filled warming mattress on the OR‐table (test OR‐table) compared with the standard OR‐table (a water‐filled warming mattress, no pressure‐reducing device) on the postoperative pressure ulcer incidence in cardiac surgery patients. Instruments. The pressure ulcer classification system of the European Pressure Ulcer Advisory Panel (EPUAP) was used for pressure ulcer grading. Results. The results show that patients lying on the 4‐cm thermoactive viscoelastic foam overlay suffer slightly more pressure ulcer (17·6%) than patients on the standard OR‐table without the foam overlay (11·1%). Because of the clinical relevance of the results, the randomized controlled trial was terminated after 175 patients at the interim analysis although the power calculation stated 350 patients. Conclusions. The combination of a 4‐cm viscoelastic foam overlay and a warming source cannot be recommended for pressure ulcer prevention on the operating room table. Relevance to clinical practice. Foam overlays are used to prevent pressure ulcers in patients. It is necessary to use such devices according to patient safety and use of resources.     

Overview of research to investigate pressure-relieving surfaces

Pressure-relieving equipment plays a key role in the prevention and treatment of pressure ulcers. Every year an increasing amount of equipment is launched on to the market. The efficacy of this equipment is traditionally qualified with interface pressure and case studies, but rarely with randomized controlled trials. With the advent of The New NHS: Modern, Dependable (Department of Health (DoH), 1997) and Pressure Ulcer Risk Assessment and Prevention (National Institute for Clinical Excellence (NICE), 2001), a clinical governance system has started to be put into place and hopefully more evidence will be produced by the manufacturers and the NHS. With some 200 different types of mattresses on the market, emphasis needs to be placed on good quality randomized clinical trials to establish effectiveness of what can be costly equipment. This article gives an overview of how, historically, pressure-relieving mattresses were marketed on case studies and interface measurement. Recently, randomized controlled clinical trials are being used to demonstrate the efficacy of the mattress and reduction in the incidence of pressure ulcers. Seating is also an important aspect in continuing 24-hours pressure area prevention and treatment. Patient posture in a chair needs to be fully understood by the practitioner and key strategies are made in this article. Little research into seating has been undertaken and is urgently required.     

What is the best support surface in prevention and treatment,as of 2012, for a patient at risk and/or suffering from pressure ulcer sore? Developing French guidelines for clinical practice

IntroductionThe use of support surfaces in the prevention and treatment of pressure ulcers prevention is an important part of care for a patient at risk and/or suffering from sore(s).ObjectivesDefine which support surfaces to use in prevention and treatment of at-risk and/or pressure sore patients.MethodologyA systematic review of the literature querying the several Pascal Biomed, PubMed and Cochrane Library databases from 2000 through 2010.Results (Grade A)In prevention, a structured foam mattress is more efficient than a standard hospital mattress. An alternating pressure mattress is more effective than a visco-elastic mattress limiting the occurrence heel pressure ulcers, but those that do occur are more serious. A low-air-loss bed is more efficient than a mixed pulsating air mattress in prevention of heel pressure ulcers. Some types of sheepskin can reduce sacral pressure ulcer incidence in orthopedic patients. Use of an overlay on an operating table limits the occurrence of peroperative and postoperative pressure ulcers. An air-fluidized bed improves pressure ulcer healing.DiscussionThe data in the literature are not always relevant and do not suffice to dictate a clinician's choices. We are compelled to recognize the methodological limitations of many studies, the lack of corporate interest in conducting such studies and the relatively small number of available trials. However, the effectiveness of some support surfaces reaches a sufficient level of evidence, especially when they are associated with postural, hydration and nutritional measures.ConclusionSupport surfaces are recommended in prevention and treatment of patients at risk and/or already suffering from pressure ulcer, and their use should constitute part of an overall preventive or curative strategy.     

Clinical Use of Interface Pressure to Predict Pressure Ulcer Development: A Systematic Review

ABSTRACT

Pressure ulcers are a large problem in subjects who use a wheelchair for their mobility. These ulcers originate beneath the bony prominences of the pelvis and progress outward as a consequence of prolonged pressure. Interface pressure is used clinically to predict and prevent pressure ulcers. However, the relation between interface pressure and the development of pressure ulcers is not clear. A systematic review was performed to address the research question of whether interface pressure can be used to predict the development of pressure ulcers or to determine the prognosis of an ulcer once developed. Seven studies were identified that measured interface pressure and used the development or healing of pressure ulcers as an outcome measure. There appears to be a weak qualitative relation between interface pressure and the development of pressure ulcers. However, no conclusive clinical threshold for the interface pressure can be given. This, combined with the influence of individual characteristics, the low internal validity of interface pressure measurement for the prediction of pressure ulcers, and an incongruent relation between pressure magnitude and duration, results in the fact that no quantification of the predictive or prognostic value of interface pressure can be given.     

Effectiveness of mattress overlays in reducing interface pressures during recumbency

This study evaluates the pressure-reduction characteristics of seven mattress overlays. Thirty subjects were evaluated on each support surface to determine the interface pressures that are generated under the most common pressure sore sites. The results of this study indicate that there is great variability in the effectiveness of traditional mattress overlays. The most effective overlays are the Roho and Akros DFD mattresses; whereas 2-inch thick convoluted foam provides no significant protection for the trochanter when the subjects were lying on their sides (lateral position).     

Preventing pressure ulcers—Are pressure-redistributing support surfaces effective? A Cochrane systematic review and meta-analysis

ObjectivesTo undertake a systematic review of the effectiveness of pressure redistributing support surfaces in the prevention of pressure ulcers.DesignSystematic review and meta-analysis.Data sourcesCochrane Wound Group Specialised Register, The Cochrane Central Register of Controlled Trials, Ovid MEDLINE, Ovid EMBASE and EBSCO CINAHL. The reference sections of included trials were searched for further trials.Review methodsRandomised controlled trials and quasi-randomised trials, published or unpublished, which assessed the effects of support surfaces in preventing pressure ulcers (of any grade), in any patient group, in any setting compared to any other support surface, were sought. Two reviewers extracted and summarised details of eligible trials using a standardised form and assessed the methodological quality of each trial using the Cochrane risk of bias tool.ResultsFifty-three eligible trials were identified with a total of 16,285 study participants. Overall the risk of bias in the included trials was high. Pooled analysis showed that: (i) foam alternatives to the standard hospital foam mattress reduce the incidence of pressure ulcers in people at risk (RR 0.40, 95% CI 0.21–0.74) and Australian standard medical sheepskins prevent pressure ulcers compared to standard care (RR 0.48, 95% CI 0.31–0.74). Pressure-redistributing overlays on the operating table compared to standard care reduce postoperative pressure ulcer incidence (RR 0.53, 95% CI 0.33–0.85).ConclusionsWhile there is good evidence that higher specification foam mattresses, sheepskins, and that some overlays in the operative setting are effective in preventing pressure ulcers, there is insufficient evidence to draw conclusions on the value of seat cushions, limb protectors and various constant low pressure devices. The relative merits of higher-tech constant low pressure and alternating pressure for prevention are unclear. More robust trials are required to address these research gaps.     

Quantification of pressure relief using interface pressure and tissue perfusion in alternating pressure air mattresses

OBJECTIVE: To examine whether the interface pressure (IP) relief provided by alternating pressure air mattresses (APAMs) is matched with maintenance of tissue perfusion over the points of contact by measuring transcutaneous oxygen and carbon dioxide (tcPO2, tcPCO2). DESIGN: Comparative analysis of 2 APAMs with a 2-parameter continuous time-based method for quantifying pressure relief (PR) and transcutaneous gas measurement for assessing tissue perfusion. SETTING: Rehabilitation research facility in a university hospital. PARTICIPANTS: Eleven able-bodied adult postgraduate student volunteers. MAIN OUTCOME MEASURES: Two full-replacement APAM systems were used. For each mattress the mean maximum and minimum interface pressures; mean peak air pressures in the mattresses; interface pressure durations below 30, 20, and 10 mmHg over a 60-minute period; mean maximum tcPCO2 and minimum tcPO2; and mean area under the tcPO2 and tcPCO2 curves were measured for each subject. RESULTS: IP on the sacrum was held below thresholds of 30, 20, and 10 mmHg longer on a 2-cell, low pressure system than on a 3-cell, high pressure system (p < .001). Integrated over time, tcPO2 levels also indicated that the 2-cell system retained oxygen levels closer to the unloaded baseline than did the 3-cell system (p < .01). tcPCO2 levels did not rise significantly (p > 0.1) compared with the baseline measurement in both mattresses. CONCLUSIONS: PR was sensitive to the design of the APAM, especially its inflation pressure, cycle time, and inflation sequence. If future trials demonstrate that PR values and transcutaneous blood gas measurements correlate significantly with the clinical incidence of pressure sore formation, then this technique may prove useful in assessing the effectiveness of alternating pressure support surfaces.     

Use of Pressurease and Airform mattresses in pressure ulcer care

Large cell dynamic air mattresses are effective in the prevention of pressure ulcers but they still have inherent problems, e.g. the ability of the mattresses to move patients along the mattress through the inflation and deflation of the cells. Also, there have been reports that the inflation and deflation of cells can cause motion sickness. This article reviews two mattresses from Sareo Healthcare Ltd: a static system, Pressurease; and a unique dynamic system, Airform. These two systems offer a cost-effective and clinically effective method of pressure ulcer prevention and therapy.