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.     

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.     

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).     

AN INVESTIGATION OF INTERFACE PRESSURES IN LOW AIR LOSS BEDS

Prospective randomised trials indicate that the low air loss bed is a successful method of treatment for pressure sores. To study the properties of these beds interface pressures were measured in two different low air loss beds. Ten healthy volunteers had eight readings at six different body sites taken supine and sitting. Occipital and heel pressures for both products exceeded 4.7 kPa, the accepted capillary closing pressure, while pressures at other sites were below this. These findings suggest that pressure relief alone is not the sole reason for the clinical acceptance of low air loss beds in the treatment of pressure sores.     

Efficacy and cost-effectiveness of the Thermo contour mattress

Use of air mattresses in reduction of pressure sore incidence is an important part of quality patient care. However, there will never be enough air mattresses to match the demand as increased education and an increase in the general provision of air mattresses can lead to an unrealistic expectation of obtaining air mattresses when required for patients. This raises the demand for air mattresses and increases costs within hospital trusts. This study examined a way to redress the balance through use of an alternative, cost-effective type of mattress (thermoelastic polymer) in the prevention of pressure sores. Prime consideration was given to the comfort of the patient. The claims of the manufacturers, Barrington Healthcare, that 'patients with Waterlow scores of 23 can be nursed safely on this product' were explored as part of the study. A total of 407 patients took part over a 6-month period. Twenty-four Thermo contour mattresses were loaned to one ward for the study and patients were allocated to the mattress through admission to the experimental ward. Patients were then split into two groups on two wards. Group B were allocated to a Thermo contour mattress and group A were nursed on air mattresses and foam mattresses generally used throughout the trust. Results showed that more patients were comfortable on the Thermo contour mattresses than on all other mattresses. Patients with Waterlow scores under 25 did not develop pressure sores on the Thermo contour mattress. However, the sample of patients with a Waterlow score of between 20 and 25 was small and therefore further research is required.     

Paraplegic Body-Support Pressure on Convoluted Foam,Waterbed, and Standard Mattresses

Comparisons were made between body-support pressures obtained when 15 male paraplegics laid on waterbed, foam, and standard mattresses. The variables examined were mattress, bone prominence, and time. The major findings were that the waterbed, in comparisons with the other mattresses, yielded significantly lower occipital, scapular, and sacral pressures at 5, 20, and 35 minutes.     

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.     

A Phantom-Based Method to Assess X-Ray Table Mattress Interface Pressures

BackgroundPressure redistribution performance of x-ray table mattresses can influence the development of pressure ulcers in at-risk populations. Interface pressure analysis, with human participants, is a common method to assess mattresses. This approach has limitations that relate to the lack of standardisation between and within humans.AimThis study aimed to develop and validate an anthropomorphic phantom-based method to assess x-ray table mattress interface pressures as an index of mattress performance.MethodsA three dimensional phantom simulating an adult’s head, pelvis, and heels was printed from x-ray computed tomography image data and attached to a metal frame 175 cm in length. Dry sand was added to the phantom head, pelvis, and heels to represent a range of human weights. Pressure distribution was assessed using XSensor. Phantom validation was achieved by comparing phantom mattress interface pressure characteristics, for five human equivalent weights, against 27 sets of human mattress interface pressure data.ResultsUsing the correlation coefficient R, phantom and human pressure data showed good correlation for the five phantom weights (R values: head = 0.993, pelvis = 0.997, and heels = 0.996).ConclusionA novel method to test x-ray mattresses for interface pressure was developed and validated. The method could have utility in the testing of x-ray mattresses that are in routine use and for new mattress development. Phantom interface pressure data could be provided by manufacturers to help inform procurement decisions when matching mattress characteristics to medical imaging demands and the underlying patient populations.     

Reducing pressure ulcer incidence in a long-term setting

Selection of appropriate pressure prevention equipment relies on risk assessment and clinical assessment of the resident/patient. Decisions are then made in combination with manufacturer's recommendations, such as interface pressure testing. However, risk assessments can over-predict and laboratory investigations do not necessarily provide an accurate picture of how individual patients will react to pressures from support services. There are few studies on visco-elastic mattresses and their benefits in reducing pressure ulcer incidence. Therefore, a small study was undertaken to review the efficacy of a pressure-reducing visco-elastic foam mattress. For the benefit of the study, a 20-bedded nursing home was provided with 20 visco-elastic mattresses (Pressurease) and 20 pressure-reducing cushions (Mediform Visco). The study aimed to demonstrate a reduction in pressure ulcer prevalence. The study involved 21 residents over a 6-month period. There was a 58.3% prevalence (of Stirling grade 1-2 pressure damage) at trial initiation. The results showed an 85.7% decrease of pressure ulcers within 4 weeks, and an overall decrease of 82.5% over the 6-month period. Comfort levels, scored by residents on a visual analogue scale, demonstrated the Pressurease mattress to be superior to the nursing home standard mattress.     

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.     

Introducing the pressure support surfaces from Kaymed

The range of support surfaces available is quite varied. It is important that both the purchaser and the users are satisfied with the quality, comfort and the pressure-reducing properties of the mattress. The mattress needs to be versatile, in that it can be used both in a patient's home or in a hospital or nursing home and also on profiling beds. The Kaymed range of mattresses offers increased comfort with low interface pressures for patients up to and including high risk. This product focus examines the Kaymed mattress and looks at the design and results of tests performed on the visco-elastic foam used in the manufacturing of the mattresses.     

Effectiveness of turning with unequal time intervals on the incidence of pressure ulcer lesions

AIM: This paper reports a study investigating whether repositioning patients lying on a pressure-reducing mattress alternately for 2 hours in a lateral position and 4 hours in a supine position reduces the incidence of pressure ulcers in comparison with repositioning every 4 hours. BACKGROUND: Repositioning is commonly recognized as an effective preventive measure. Almost no research has been carried out so far on the necessary turning frequencies to prevent pressure ulcer lesions. The pressure is higher in a lateral than in a supine position. METHOD: A two-arm randomized controlled trial was conducted in 16 Belgian elder care nursing homes. Patients with non-blanchable erythema were randomly assigned to either an experimental or a control group. In the experimental group (n = 122), patients were repositioned alternately 2 hours in a lateral position and 4 hours in a supine position. In the control group (n = 113), patients were repositioned every 4 hours. The sitting protocol was identical in both groups. Pressure areas were observed daily and classified according to the four grades of the European Pressure Ulcer Advisory Panel. RESULTS: In the experimental group, 16.4% patients developed a pressure ulcer lesion (grade 2-4), while 21.2% did so in the control group. The incidence was not statistically significantly different between the two groups (P = 0.40). The severity (P = 0.65) and location (P = 0.19) of pressure ulcer lesions, and the time to developing them (P = 0.29) were also similar in both groups. No patient developed a pressure ulcer at the hips. A considerable number of patients changed from a lateral to a supine position between the turning intervals. CONCLUSION: More frequent repositioning on a pressure-reducing mattress does not necessarily lead to fewer pressure ulcer lesions and consequently cannot be considered as a more effective preventive measure.     

Special mattresses: effectiveness in preventing decubitus ulcers in chronic neurologic patients

Thirty-two chronic neurologic patients between 19 and 60 years of age were randomly assigned, for a period of three months, to either an alternating air mattress or a silicore mattress to test the preventive qualities of special mattresses in the occurrence of decubitus ulcers. The two groups were comparable on the variables of age, weight, diagnoses, history of disease process, history of being wheelchair bound, history of previous pressures, and mean scores on Norton's scale of risk, which is based on the subject's physical condition, mental alertness, ambulation, mobility and incontinence. No significant differences were observed in the preventive qualities of the two types of special mattresses in terms of the incidence, location, severity, or healing duration of the subjects' decubitus ulcers. Improved studies of common special mattresses are suggested.     

服用抗精神病药物患者血压、心率的测量与观察

为了降低服用抗精神病药物患者体位性低血压的发生率，对62例精神分裂症患者在增药期间，取不同体位进行了血压和心率的测量。结果：平卧位的收缩压、舒张压、心率与直立位比较（经配对t检验）差异有非常显著性（P＜0．01）。直立位与平卧位相比，心率平均快41次／min，舒张压平均高1．1kPa，而收缩压平均低1．32kPa。其中有5例患者平卧位收缩压正常，而直立位时收缩压＜12kPa。作者提出：①给服用抗精神病药物患者测量血压、心率时，应分别取平卧和直立位进行测量，才能了解患者血压和心率的变化。②增药期间应采取直立位测量，对预防体位性低血压有重要意义。     

Laboratory performance of alternating pressure air mattresses component and sequelae

The performance of three different alternating pressure air mattresses with different geometries of air cell were compared (Nimbus 3, Heritage, Tamora Plus), using simple performance indices based on pressure mapping. The aim of this study was to examine the effect on performance of elevating the backrest and thigh section of the bed into sitting position. Ten healthy volunteers of various sizes were pressure-mapped over the full pressure cycle on three alternating pressure air mattresseses with differing cell geometries. This was then repeated with the beds profiled to a sitting position. Performance of the alternating pressure air mattresses in terms of their ability to redistribute pressure dynamically was assessed in the different positions. The different alternating pressure air mattresses performed similarly with the bed in the lying flat position, but smaller cells appeared to be more effective in the sitting position. A conclusion was made that cell geometry may have an effect on the ability of the mattress to achieve alternating behaviour in the sitting position.     

Influence of clinical findings, positional manoeuvres, and systolic ankle arterial pressure on transcutaneous oxygen tension in peripheral arterial occlusive disease

The mutual effects of systolic ankle arterial pressures, positional manoeuvres, and calf artery occlusions on transcutaneous oxygen partial pressures (tcpO2) were studied in 388 legs of 258 patients with peripheral arterial occlusive disease (PAOD). The tcpO2-vs-perfusion pressure relationship could be satisfactorily fitted by a non-linear regression model deduced from the tcpO2 theory. Flow-insensitive ranges of tcpO2-vs-flow hyperbolas were reduced by both leg lowering and moving the electrode towards proximal measuring sites. Lower tcpO2 values were found in case of occluded compared to patent calf arteries at ankle arterial pressure indices below 0.4. The tcpO2 positional variability increased with worsening hemodynamic compensation and was most pronounced in critical limb ischaemia (ischaemic rest pain, non-healing ulcerations). According to a retrospective analysis, a critical ischaemia could be assumed if supine and sitting tcpO2-values exceed neither 10 nor 45 mmHg, respectively.     

Preventing pressure ulcers: choosing a mattress

The standard hospital mattress is not suitable for patients at risk of developing pressure ulcers. The type of mattress or overlay system they require will depend on their pressure ulcer risk, medical history and local practice. This article provides a guide to pressure-relieving mattresses.     

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.     

Esprit HR mattress cover in pressure ulcer prevention

Modern mattresses provide soft dense foam, which permits the redistribution of pressure on the patient over a wider area - away from bony prominences where pressure ulcers usually occur. The material used in producing multistretch covers for the new mattresses had a tendency to delaminate as a result of a combination of heat, moisture and inappropriate cleansing techniques causing the water barriers to fall. In partnership with York Health NHS Trust and the material manufacturer, STM Healthcare produced a mattress cover (Esprit HR) which was able to withstand higher pressure from heat and moisture and greatly extended the life expectancy of the Esprit HR mattress.     

The QUATTRO ACUTE mattress and pressure ulcer prevention

There are a plethora of mattresses on the market and nurses are not always sure which mattress to select for each individual patient. This article outlines the issues in preventing and understanding pressure ulcers and the performance of the QUATTRO ACUTE trade mark mattress, manufactured by Talley Medical.