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Pressure relieving support surfaces: a randomised evaluation.

OBJECTIVES: To determine differences between alternating pressure overlays and alternating pressure replacement mattresses with respect to the development of new pressure ulcers, healing of existing pressure ulcers, patient acceptability and cost-effectiveness of the different pressure-relieving surfaces. Also to investigate the specific additional impact of pressure ulcers on patients' well-being. DESIGN: A multicentre, randomised, controlled, open, fixed sample, parallel-group trial with equal randomisation was undertaken. The trial used remote, concealed allocation and intention-to-treat (ITT) analysis. The main trial design was supplemented with a qualitative study involving a purposive sample of 20-30 patients who developed pressure ulcers, to assess the impact of the pressure ulcers on their well-being. In addition, a focus group interview was carried out with clinical research nurses, who participated in the PRESSURE (Pressure RElieving Support SUrfaces: a Randomised Evaluation) Trial, to explore the experiences of their role and observations of pressure area care. SETTING: The study took place in 11 hospital-based research centres within six NHS trusts in England. PARTICIPANTS: Acute and elective patients aged 55 years or older and admitted to vascular, orthopaedic, medical or care of the elderly wards in the previous 24 hours were investigated. INTERVENTIONS: Patients were randomised to either an alternating pressure overlay or an alternating pressure mattress replacement, with mattress specifications clearly defined to enable the inclusion of centres using products from different manufacturers, and to exclude hybrid mattress systems (which either combine foam or constant low pressure with alternating pressure in one mattress, or can be used as either an overlay or a replacement mattress). MAIN OUTCOME MEASURES: Development of a new pressure ulcer (grade < or =2, i.e. partial-thickness wound involving epidermis/dermis only) on any skin site. Also healing of existing pressures ulcers, patient acceptability and cost-effectiveness. RESULTS: In total, 6155 patients were assessed for eligibility to the trial and 1972 were randomised: 990 to the alternating pressure overlay (989 after one postrandomisation exclusion) and 982 to the alternating pressure mattress replacement. ITT analysis found no statistically significant difference in the proportions of patients developing a new pressure ulcer of grade 2 or above [10.7% overlay patients, 10.3% mattress replacement patients, a difference of 0.4%, 95% confidence interval (CI) -2.3 to 3.1%, p = 0.75]. When logistic regression analysis was used to adjust for minimisation factors and prespecified baseline covariates, there was no difference between the mattresses with respect to the odds of ulceration (odds ratio 0.94, 95% CI 0.68 to 1.29). There was no evidence of a difference between the mattress groups with respect to time to healing (p = 0.86). The Kaplan-Meier estimate of the median time to healing was 20 days for each intervention. More patients allocated overlays requested mattress changes due to dissatisfaction (23.3%) than mattress replacement patients (18.9%, p = 0.02) and more than one-third of patients reporting difficulties associated with movement in bed and getting into or out of bed. There is a higher probability (64%) that alternating mattress replacements are cost-saving; they were associated with lower overall costs (74.50 pounds sterling per patient on average, mainly due to reduced length of stay) and greater benefits (a delay in time to ulceration of 10.64 days on average). Patients' accounts highlighted that the development of a pressure ulcer could be pivotal in the trajectory from illness to recovery, by preventing full recovery or causing varied impacts on their quality of life. CONCLUSIONS: There is no difference between alternating pressure mattress replacements and overlays in terms of the proportion of patients developing new pressure ulcers; however, alternating pressure mattress replacements are more likely to be cost-saving. The results suggest that when renewing alternating pressure surfaces or ordering equipment within a rental contract, mattress replacements should be specified; however, overlays are acceptable if no replacement mattress is available. Similarly, patient preferences can be supported, without any great increase in risk, if individual patients request an overlay rather than a replacement mattress. Further research could include a randomised controlled trial comparing alternating pressure mattress replacements and high-specification foam mattresses in patients at moderate to high risk; an accurate costing study to understand better how much pressure ulcers cost health and social services in the UK; and trials in higher risk groups of patients. Also future trials should measure time to ulceration as the primary end-point, since this is more informative economically and possibly also from a patient and clinical perspective.

Bedding and Linens↗

Coupling force distribution and finite element model for calculating the consequences of distributed force input.

INTRODUCTION:: The aim of the study is to repeat an important step in the development of biomechanics in relation to pressure distribution measurements. Just one decade ago (a) one channel force measurement and (b) 'one channel models' were developed to a certain level of sophistication so that the force could be used by the model to calculate movement and load of the body. In contrast, work in the field of pressure distribution was focused to (a) multi-channel measurement, but (b) no models were used to calculate the consequences of the forces measured. In the following, a multi-channel Finite Element Model (FEM) is introduced for that purpose. The body studied is a mattress; the results attained are helpful under two aspects. Firstly, the FEM provides information on the stress inside the mattress; this aspect is of interest for nearly all bodies. The second aspect is a special problem of mattresses and the like: as the user covers the surface of the mattress, there is no direct information on the shape of mattress and the human body, and measuring procedures for the shape are quite difficult and coarse. METHODS:: The mattress is modelled as a set of a(*)b(*)c vertical springs where c springs are standing on top of each other. The springs are interconnected in a horizontal direction. On top of the set an extra layer with very strong horizontal coupling is placed, which is the model of the cover fabric. Pressure distribution measurements showed that the fabric is responsible for the so called 'hammock effect' which significantly reduces the quality of the mattress. a(*)b forces are input into the model; each force influences all springs because of the horizontal coupling. The distance of the springs is designed according to the distance of the force sensors, which in turn reflect the importance of the mattress area studied. In the trunk area the springs are spaced 15(*)30 mm, in the remaining mattress area the spacing is 72.5(*)43 mm; two springs are standing on top of each other. Each spring defines a volume element, the corner points of each element are connected to the neighbouring element, transferring stress and strain this way. The constraints are specific for the mattress type. APPLICATION:: Utilizing this model and a software package I-DEAS installed on a work station, stress and displacement to three axes of each volume are calculated, moreover the shape of the mattress surface and thus the shape of the body lying on it are attained. The standard measuring procedure is as follows: 1. A mattress is loaded by boards and balls so that the shape of the surface under pressure is known; from pressure distribution measurements the model calculates the spring data. 2. Various subjects are placed on the mattress and measured; the model calculates the surface shape of their body utilizing the spring data. 3. Data of lying quality (concerning comfort and support) are assessed from the body shape and recommendations concerning improvement of the mattress are derived.

Journal Article↗

Pain and tissue-interface pressures during spine-board immobilization.

STUDY OBJECTIVES: Although spine boards are one of the main EMS means of immobilization and transportation, few studies have addressed the discomfort and potential harmful consequences of using this common EMS tool. We compared the levels of pain and tissue-interface (contact) pressures in volunteers immobilized on spine boards with and without interposed air mattresses. DESIGN: Prospective crossover study. SETTING: Emergency department of Methodist Hospital of Indiana, Indianapolis, Indiana. PARTICIPANTS: Twenty healthy volunteers who had not taken any analgesic drugs in the preceding 24 hours, were not experiencing any pain at the time of the study, and did not have history of chronic back pain. INTERVENTIONS: To simulate prehospital transport conditions, we immobilized volunteers with hard cervical collars and single-buckle chest straps on wooden spine boards with or without commercially available medical air mattresses. The crossover order was randomized. After 80 minutes, immobilization measures were discontinued and the subjects were allowed to get off the boards for a recovery period of 60 minutes. Subjects were then studied for a second 80-minute period with the opposite intervention. At baseline and at 20-minute intervals, the level of pain was rated with a 100-mm visual analog scale. Tissue-interface pressures were measured at the occiput, sacrum, and left heel. RESULTS: Mean pain on the visual analog scale was 9.7 mm at the end of the mattress period and 37.5 mm at the end of the no-mattress period (P = .0001). Although there were no significant differences in pain between the two groups at time 0, volunteers reported significantly more pain during the no-mattress period at 20 (P = .003), 40 (P = .0001), and 60 minutes (P = .0001). All 20 subjects reported that immobilization on the spine board with the mattress was "much better" (five-point scale) than that without the mattress. Interface pressure levels were significantly less in the mattress period than in the no-mattress period measured at occiput (P = .0001), sacrum (P = .0001), and heel (P = .0001). CONCLUSION: In a simulated immobilization experiment, healthy volunteers reported significantly less pain during immobilization on a spine board with an interposed air mattress than during that on a spine board without a mattress. Tissue-interface pressures were significantly higher on spine boards without air mattresses. This and previous studies suggest that immobilization on rigid spine boards is painful and may produce tissue-interface pressure high enough to result in the development of pressure necrosis ("bedsores"). Emergency care providers should consider the use of interposed air mattresses to reduce the pain and potential tissue injury associated with immobilization on rigid spine boards.

Adolescent↗

The effect of a dynamic pressure-redistributing bed support surface upon systemic lymph flow and composition.

INTRODUCTION: It has been postulated that lymphatic insufficiency may have a key role in pressure ulcer development. Our hypothesis is that the particular dynamic action of the Airwave mattress directly improves lymphatic circulation compared to conventional hospital mattresses. METHODS: Seven anesthetized sheep (40-48 kg) prepared with chronic prefemoral lymph fistulas and vascular catheters were first placed on a standard hospital mattress. Following 30 minutes of equilibration, a 2 hr control period was started measuring lymph flow and vascular pressures. The standard mattress was then exchanged for an active Airwave mattress (Pegasus Egerton, Ltd.) and after 30 minutes of equilibration monitored as above. After 2.5 hr, the support surface was then switched back to the standard mattress and monitored as before. Data are mean +/- sem. RESULTS: Initially, on the standard mattress, lymph flow was 1.0 +/- 0.2 ml/30 min and increased significantly more than 3 fold on the Aireave mattress to 3.7 +/- 0.7 ml/30 min. Upon return to the standard mattress, lymph flow decreased to 1.2 +/- 0.2 ml/30 min. Hemodynamic variables and arterial blood gases were constant. Lymphatic protein transport increased significantly from 1.3 +/- 0.3 micrograms/min to 4.3 +/- 1.0 micrograms/min when placed on the test mattress and decreased when returned to the standard mattress to 1.3 +/- 0.2 micrograms/min. Similar rates of lymph flow were seen upon a variant of the Airwave mattress (Cairwave Therapy System). CONCLUSIONS: Results support the hypothesis that the Airwave's action increased the lymph flow compared to a standard hospital mattress. The dynamic cycle may act to aid the pumping action of lymphatics by reducing pressure which would otherwise collapse and compress lymphatics leading to local edema and tissue swelling.

Animals↗

Factors affecting stall use for different freestall bases.

The objective of this study was to compare stall use (stall occupancy and cow position) by barn side for factors affecting stall use. A closed circuit television system recorded stall use four times per day for a 9-mo period starting May 9, 2001. Six factors were analyzed: stall base, distance to water, stall location within stall base section, stall location within barn, inside barn temperature, and length of time cows were exposed to stall bases. Two barn sides with different stocking densities were analyzed: low (66%), with cows milked by robotic milker; and high (100%), with cows milked 2X in parlor. Six stall base types were tested: two mattresses, a waterbed, a rubber mat, concrete, and sand (high side only). The base types were grouped 3 to 7 stalls/section and randomly placed in each row. Cows spent more time in mattress-based stalls, but the highest percentage lying was in sand-based stalls. The following significant stall occupancy percentages were found: sand had the highest percentage of cows lying on the high stocking density side (69%), followed by mattress type 1 (65%) > mattress type 2 (57%) > waterbed (45%) > rubber mat (33%) > concrete (23%). Mattress type 1 had the highest percentage stalls occupied (88%), followed by mattress type 2 (84%) > sand (79%) > soft rubber mat (65%) > waterbed (62%) > concrete (39%). On the low stocking rate side, mattress type 1 had the highest percentage cows lying (45%) and occupied (59.6%), followed by mattress type 2 > waterbed > soft rubber mat > concrete. Cow lying and stalls occupied percentages were highest for stalls 1) not at the end of a section, and 2) on the outside row, and varied by base type for time cows exposed to stalls and inside barn temperature. Lying and occupied percentages were different for different mattress types. The percentage of stalls with cows standing was higher for mat and mattress-based stalls. Results show mattress type 1 and sand to be superior and rubber mats and concrete inferior stall bases.

Animals↗

The Melbourne house dust mite study: eliminating house dust mites in the domestic environment.

BACKGROUND: Hypersensitivity to house dust mite allergens is associated with increased asthma morbidity. Asthma severity appears to be related to the degree of mite allergen exposure. Short-term studies suggest that complete avoidance reduces disease severity. OBJECTIVE: The study was designed to assess the effect of different mattress covers and floor coverings on mite allergen concentrations in the homes of mite-sensitive children with asthma in the city of Melbourne, Australia. METHODS: Mite allergen Der p 1 concentration was measured on mattress covers, mattress surfaces, and carpeted and uncarpeted floors in 107 dwellings; and measurement was performed on three occasions over a 5-month period. After the first sampling, all mattress covers and impermeable encasements were permanently removed. RESULTS: The initial geometric mean concentrations of Der p 1 (micrograms per gram of fine dust) from the surfaces of sheepskin, wool, and cotton mattress coverings were greater than those from the surfaces of impermeable mattress encasements (116, 113, and 19 vs 0.4) (p < 0.001); corresponding concentrations on the underlying mattresses were 142, 38, 20, and 0.6, respectively (p < 0.05 to 0.001). At the end of the study these mattress surface concentrations were 79, 65, 9.7, and 3.1, respectively. In 24 dwellings an uncarpeted room was adjacent to a carpeted room. At each visit the concentration of Der p 1 in uncarpeted rooms was below the reported threshold for sensitization and significantly less than that in the adjacent carpeted room. CONCLUSION: In homes of children with asthma, "asthmogenic" concentrations of Der p 1 were found on nonencased mattresses and carpeted floors, but the use of impermeable mattress encasements and carpet exclusion were associated with concentrations of Der p 1 below the reported threshold for sensitization.

Adolescent↗

House dust mite species and allergen levels in Galicia, Spain: a cross-sectional, multicenter, comparative study.

BACKGROUND AND OBJECTIVES: Mites are important sources of allergens in Galicia, Spain. The objective of this study were to identify the main mite species and to determine allergen levels in mattresses from different locations in Galicia. MATERIAL AND METHODS: Dust samples were collected with a portable vacuum cleaner for 2 minutes from 2 m2 of the surface of the mattress used by mite allergic patients and controls. After collection, samples were immediatel frozen. Mite species were collected, identified, and counted, and the results expressed as mites per gram of dust. Mite allergen levels (Der p 1 and Der f 1) were measured using monoclonal antibodies. All individuals answered a questionnaire about the characteristics of their homes. RESULTS: A total of 332 dust samples were collected (112 from mite allergic patients and 220 from controls). Thirty-two species were identified. The mean age +/-SD of all the participants was 32.4 +/- 20.8 years and of the mattresses 7.6 +/- 5.9 years. The geometric mean of the total mite counts was 910.2 mites per gram (896.2 mites per gram in the mattresses of mite allergic patients and 917.3 in the mattresses of control subjects; P > .05). The main species was Dermatophagoides pteronyssinus, which was present in 97.6% of the samples (geometric mean, 584.7 mites per gram). The geometric mean level of Der p 1 was 13.1 microg/g of dust: 11.9 in the mattresses of mite allergic patients and 13.8 in the mattresses of control subjects. The geometric mean level of Der f1 was 1.1 microg/g: 1.5 in the mattresses of mite allergic patients and 0.8 in the mattresses of control subjects. Environmental risk factors associated with high mite counts included obvious signs of humidity in the bedroom and the age of the mattress. CONCLUSIONS: The mite fauna in Galicia is comprised of many species, several of which are known to be of allergologic importance. The total population is exposed to very high levels of mite allergens.

Adolescent↗

Support surfaces for pressure ulcer prevention.

BACKGROUND: Pressure ulcers (also known as bedsores, pressure sores, decubitus ulcers) are areas of localised damage to the skin and underlying tissue due to pressure, shear or friction. They are common in the elderly and immobile and costly in financial and human terms. Pressure-relieving beds, mattresses and seat cushions are widely used as aids to prevention in both institutional and non-institutional settings. OBJECTIVES: This systematic review seeks to answer the following questions: to what extent do pressure-relieving cushions, beds, mattress overlays and mattress replacements reduce the incidence of pressure ulcers compared with standard support surfaces? how effective are different pressure-relieving surfaces in preventing pressure ulcers, compared to one another? SEARCH STRATEGY: The Specialised Trials Register of the Cochrane Wounds Group (compiled from regular searches of many electronic databases including MEDLINE, CINAHL and EMBASE plus handsearching of specialist journals and conference proceedings) was searched up to January 2004, Issue 3, 2004 of the Cochrane Central Register of Controlled Trials was also searched. The reference sections of included studies were searched for further trials. SELECTION CRITERIA: Randomised controlled trials (RCTs), published or unpublished, which assessed the effectiveness of beds, mattresses, mattress overlays, and seating cushions for the prevention of pressure ulcers, in any patient group, in any setting. RCTs were eligible for inclusion if they reported an objective, clinical outcome measure such as incidence and severity of new of pressure ulcers developed. Studies which only reported proxy outcome measures such as interface pressure were excluded. DATA COLLECTION AND ANALYSIS: Trial data were extracted by one researcher and checked by a second. The results from each study are presented as relative risk for dichotomous variables. Where deemed appropriate, similar studies were pooled in a meta analysis. MAIN RESULTS: 41 RCTs were included in the review. Foam alternatives to the standard hospital foam mattress can reduce the incidence of pressure ulcers in people at risk. The relative merits of alternating and constant low pressure devices, and of the different alternating pressure devices for pressure ulcer prevention are unclear.Pressure-relieving overlays on the operating table have been shown to reduce postoperative pressure ulcer incidence, although one study indicated that an overlay resulted in adverse skin changes. One trial indicated that Australian standard medical sheepskins prevented pressure ulcers. There is insufficient evidence to draw conclusions on the value of seat cushions, limb protectors and various constant low pressure devices as pressure ulcer prevention strategies.A study of Accident & Emergency trolley overlays did not identify a reduction in pressure ulcer incidence. There are tentative indications that foot waffle heel elevators, a particular low air loss hydrotherapy mattress and an operating theatre overlay are harmful. REVIEWERS' CONCLUSIONS: In people at high risk of pressure ulcer development, consideration should be given to the use of higher specification foam mattresses rather than standard hospital foam mattresses. The relative merits of higher-tech constant low pressure and alternating pressure for prevention are unclear. Organisations might consider the use of pressure relief for high risk patients in the operating theatre, as this is associated with a reduction in post-operative incidence of pressure ulcers. Seat cushions and overlays designed for use in Accident & Emergency settings have not been adequately evaluated.

Beds↗

Use of a permanent magnetic field to inhibit the development of canine osteoarthritis.

This study was designed to determine the potential of a permanent magnetic field to inhibit the progression of osteoarthritis (OA) in a canine model. The magnetic field was created by 72 domino-sized ceramic magnets with surface field strength of 1100 G (0.11 T). The magnetic field strength at the surface of the mattress was 450-500 G (45-50 mT) and was equally distributed over the mattress surface. Eighteen animals had closed resection of their right stifle anterior cruciate ligament. Their kennel floors were covered in one of three ways: no floor mattress (OA) (N = 6); a floor mattress with domino-sized ceramic pieces placed between two layers of foam (sham control OA-MAT) (N = 6); or a floor mattress with domino-sized ceramic permanent magnets placed between two layers of foam (OA-MAT-MAG) (N = 6). Animals were kept in their cages except for 4 h of exercise each day. The left stifle of six animals served as the normal control. The stifle joints were examined at 12 weeks for synovial effusion, gross anatomic appearance, microscopic anatomic appearance (Mankin score), and metalloproteinase (MMP)-1 and -3. Macroscopically, the OA-MAT-MAG group appeared to have less synovitis, less synovial effusion, less disruption of the cartilage surface, and less cartilage ulceration than did the OA group or the control mattress group. The mean Mankin score for the OA-MAT-MAG group was less than that for the OA group (4.2 +/- 0.8 vs. 6.7 +/- 0.3; P <.05) and the control mattress group (4.2 +/- 0.8 vs. 5.2 +/- 0.8; P >.05), but greater than that for the normal left group (4.2 +/- 0.8 vs. 1.0 +/- 0.4; P <.05). These scores show a trend of improvement for OA-MAT-MAG group but the difference with the sham control OA-MAT group was not statistically significant. In immunohistochemical studies, the OA-MAT-MAG group cartilage was stained less heavily for MMP-1 and MMP-3 than were the OA group cartilage and the control mattress group cartilage, but did not differ significantly in MMP-1 and MMP-3 from the normal left group cartilage. The OA-MAT-MAG group did not differ from the normal left group in MMP-3 as determined by Western blot analysis. The study suggests that OA of the medial femoral condyle developed in a canine model exposed to a magnetic field may be inhibited beyond the benefit provided by mattress. Further studies are needed to delineate more precisely the effect of the magnetic field in reducing the severity of OA.

Animals↗

Mite antigen in house dust: relationship with different housing characteristics in The Netherlands.

As part of a case-controlled study on the relationship between home dampness and respiratory symptoms of children, the concentration of the major allergen of Dermatophagoides pteronyssinus (Der p I) in floor dust and mattress dust in 516 dwellings in the Netherlands was measured. A checklist, completed by the investigators, was used to obtain information on home and occupant characteristics, which may have an impact on the Der p I concentration in house dust. The geometric mean mite antigen concentrations were 2370 ng Der p I/g floor dust for the living room, 2201 ng Der p I/g floor dust for the bedroom and 5075 ng Der p I/g mattress dust. In 86% of the houses the maximum concentration was higher than 2000 ng Der p I/g dust, that is regarded as representing a risk for genetically predisposed individuals for the development of specific IgE to house dust mite allergen. In 55% of the houses the maximum concentration exceeded 10,000 ng Der p I/g dust, regarded as a risk factor for acute attacks of asthma for mite allergic patients. The Der p I concentrations in dust from carpeted floors were six to 14 times higher than in dust from floors with a smooth floor covering. Higher Der p I concentrations in floor dust were also significantly associated with increasing age of the dwelling and of the floor covering, with an increasing number of occupants, and with the absence of floor insulation. For mattress dust, the age of the mattress, the presence of an outer cavity wall and mechanical ventilation were important factors. Older mattresses had higher levels, and mattress dust from bedrooms with solid brick outer walls had higher levels than that from bedrooms with outer cavity walls. Mattresses in homes with continuous mechanical ventilation had almost twice lower levels than mattresses in homes with natural ventilation. There was a tendency towards higher Der p I concentrations in dust in homes with reported or observed signs of dampness. The Der p I concentrations in dust from carpeted bedroom floors and mattresses were positively associated with the average relative humidity in the bedroom over a period of 3-6 weeks in a subset of the homes where relative humidity was measured. Similar results were obtained using the concentrations of Der p I in ng/m2 instead of ng/g dust. The results obtained in this study are of importance for planning and evaluating allergen avoidance measures advised to mite allergic patients.

Adult↗

Scleral outfolding for macular translocation.

PURPOSE: To report experimental study and clinical observation of scleral outfolding for macular translocation. METHODS: In six human cadaver eyes, circumferential mattress sutures to create sclera infoldings were compared with radial-interrupted mattress sutures to create scleral outfoldings. In a 75-year-old man with macular degeneration and choroidal neovascular membrane, radial-interrupted mattress sutures were used for macular translocation. RESULTS: In the human cadaver eyes, circumferential mattress sutures for scleral infolding created an average decrease in corresponding internal anteroposterior retinal contour of 0.36 mm. Radial-interrupted mattress sutures for scleral outfoldings created an average decrease in the corresponding internal anteroposterior retinal contour of 4. 61 mm. The statistical significance of the difference between infoldings of the sclera versus outfoldings of the sclera had a P value of.0001. CONCLUSIONS: Initial experimental and clinical study suggests that radial-interrupted mattress sutures may generate more shortening of the internal scleral surface and greater macular translocation than circumferential mattress sutures. Additional studies are needed to evaluate the long-term effects of radial-interrupted mattress sutures and macular translocation for treatment of subfoveal choroidal neovascularization secondary to age-related macular degeneration.

Aged↗

Mite and pet allergen levels in homes of children born to allergic and nonallergic parents: the PIAMA study.

The Prevention and Incidence of Asthma and Mite Allergy (PIAMA) study is a birth cohort study that investigates the influence of allergen exposure on the development of allergy and asthma in the first several years of life. The objectives of this study were to investigate the relationship between a family history of allergy and/or asthma and exposure of newborn children to mite and pet allergen and to study the influence of different home and occupant characteristics on mite allergen exposure. Dust was sampled from the child's mattress and the parental mattress at 3 months after birth of the index child and analyzed for mite and pet allergens. Subjects were divided in groups according to history of asthma and allergy in their parents, and allergen exposure was studied in the different groups. Cat allergen exposure was significantly lower on parental mattresses in families with allergic mothers, but dog allergen exposure was not different. Mite allergen exposure was lower on parental mattresses in families with allergic mothers. Use of mite allergen-impermeable mattress covers reduced mite allergen exposure. Some other characteristics such as age of home and mattress were also found to influence mite allergen exposure. Parental mattresses in homes of allergic mothers had lower cat and mite (but not dog) allergen loadings than mattresses in homes of nonallergic parents. Paternal (as opposed to maternal) allergy seemed to have little influence.

Adult↗

The Egerton Convertible II and the Elite 3 bed system.

Low air loss bed systems have proved successful in the management of severe pressure sores but they tend to be expensive. The Convertible II promises to provide many of the features of a low air loss bed at a much reduced cost. It is essentially a mattress replacement that can be used for various beds, including contouring-base beds. It is a component of the Elite 3 bed system which comprises an electrically powered contouring bed (with its own air pump) and three different mattresses: the mattress of the Convertible II is Mattress 3 of this system; Mattress 2 is an alternating-pressure air mattress; and Mattress 1 is a static air mattress with a foam envelope. The advantages and disadvantages of these products are discussed and it is suggested that the allocation of patients to the various supports can be facilitated by using a pressure sore risk-assessment score.

Beds↗

Indoor allergen levels in day nurseries.

BACKGROUND: Because allergic sensitization seems to occur especially during infancy, we decided to evaluate such an exposure in day nurseries. METHODS: Thirty day nurseries in Marseilles, which were selected at random, were visited during 2 weeks in April 1993. Routine cleaning includes daily cleaning of smooth floors, weekly laundering of sheets, and monthly cleaning of soft toys. Mattresses are encased in synthetic covers. Dust samples were collected from four settings: infants' mattresses and pillows, smooth floors, and soft toys. Levels of mite, cockroach, cat, and dog allergens were analyzed with a monoclonal antibody-based ELISA. RESULTS: Mite allergen levels were lower than the proposed threshold level for sensitization (2 micrograms/gm of dust) on 94% of mattresses and soft toys and on 100% of floors and pillows. Cat allergen levels in mattresses ranged from less than 0.1 to 4.5 micrograms/gm dust. On floors, cat allergen levels ranged from less than 0.1 to 2.4 micrograms/gm dust. Only 10% of pillows and soft toys had levels greater than 2 micrograms/gm of dust. Fel d I levels were significantly higher (p < 0.03) in mattresses from nurseries with curtains and were correlated with the percentage of children with a cat at home. In almost all day nurseries, cockroach allergen (Bla g I and Bla g II) levels were very low. Only three samples from mattresses had dog allergen levels greater than 2 micrograms of Can f I allergen per gram of dust. On floors the level was always lower than 2 micrograms/gm. CONCLUSIONS: These data clearly show that indoor allergen levels are much lower in day nurseries than in most houses. Most samples contain allergen levels below threshold levels for sensitization. Thus children of atopic parents are less likely to become sensitized to indoor allergens in day nurseries than in their own homes. In addition, this study emphasizes the efficacy of avoidance measures such as use of synthetic protective mattress covers, frequent washing of sheets and soft toys, and avoidance of carpets and curtains.

Allergens↗

Cost-effectiveness of pressure-relieving devices for the prevention and treatment of pressure ulcers.

OBJECTIVES: The cost-effectiveness of alternating pressure-relieving devices, mattress replacements, and mattress overlays compared with a standard hospital (high-specification foam mattress) for the prevention and treatment of pressure ulcers in hospital patients in the United Kingdom was investigated. METHODS: A decision-analytic model was constructed to evaluate different strategies to prevent or treat pressure ulcers. Three scenarios were evaluated: the prevention of pressure ulcers, the treatment of superficial ulcers, and the treatment of severe ulcers. Epidemiological and effectiveness data were obtained from the clinical literature. Expert opinion using a rating scale technique was used to obtain quality of life data. Costs of the devices were obtained from manufacturers, whereas costs of treatment were obtained from the literature. Uncertainty was explored through probabilistic sensitivity analysis. RESULTS: Using 30,000 pounds sterling/QALY (quality-adjusted life year) as the decision-maker's cut off point (the current UK standard), in scenario 1 (prevention), the cost-effective strategy was the mattress overlay at 1, 4, and 12 weeks. In scenarios 2 and 3, the cost-effective strategy was the mattress replacement at 1, 4, and 12 weeks. Standard care was a dominated intervention in all scenarios for values of the decision-maker's ceiling ratio ranging from 5,000 pounds sterling to 100,000 pounds sterling/QALY. However, the probabilistic sensitivity analysis results reflected the high uncertainty surrounding the choice of devices. CONCLUSIONS: Current information suggests that alternating pressure mattress overlays may be cost-effective for the prevention of pressure ulcers, whereas alternating pressure mattress replacements appears to be cost-effective for the treatment of superficial and severe pressure ulcers.

Beds↗

Biomechanical comparison of traditional and locked suture configurations for arthroscopic repairs of the rotator cuff.

BACKGROUND: The optimal suture configuration for arthroscopic rotator cuff repairs is controversial. "Locked" suture configurations, which use a combination of simple and transverse suture loops, have demonstrated better fixation strength than have traditional simple and horizontal mattress techniques. PURPOSE: To compare traditional arthroscopic suture configurations to locked arthroscopic configurations in ability to resist gap formation under cyclic loading. STUDY DESIGN: Controlled laboratory study. METHODS: Crescent-shaped defects were created at the infraspinatus tendon insertion in 32 bovine shoulders. Four arthroscopic suture configurations were tested (8 specimens in each group): simple (group 1), horizontal mattress (group 2), locked mattress (group 3), and locked inverted mattress (group 4). A metal corkscrew suture anchor doubly loaded with No. 2 Fiberwire suture was used for the repairs. A cyclic loading protocol with application of forces from 10 to 180 N for a maximum of 2,500 cycles was used. The number of cycles required to form gaps of 5 mm and 10 mm was recorded. RESULTS: The locked mattress configuration (group 3) outperformed all other groups in resisting 5-mm gap formation (P < .0001), requiring a mean of 628 cycles in comparison to 65, 193, and 197 cycles for groups 1, 2, and 4, respectively. Both locked configurations (groups 3 and 4) were superior to traditional simple and horizontal mattress configurations in resisting 10-mm gap formation. CONCLUSION: The locked mattress suturing technique (group 3) provided the most secure tendon fixation of all arthroscopic configurations tested. CLINICAL RELEVANCE: The use of locked suture configurations for arthroscopic rotator cuff repairs may enhance tendon fixation and limit gap formation in the early postoperative period.

Animals↗

Influence of support on intra-abdominal pressure, hepatic kinetics of indocyanine green and extravascular lung water during prone positioning in patients with ARDS: a randomized crossover study.

INTRODUCTION: Prone positioning (PP) on an air-cushioned mattress is associated with a limited increase in intra-abdominal pressure (IAP) and an absence of organ dysfunction. The respective influence of posture by itself and the type of mattress on these limited modifications during the PP procedure remains unclear. The aim of this study was to evaluate whether the type of support modifies IAP, extravascular lung water (EVLW) and the plasma disappearance rate of indocyanine green (PDRICG) during PP. METHODS: A prospective, randomized, crossover study of 20 patients with acute respiratory distress syndrome (ARDS) was conducted in a medical intensive care unit in a teaching hospital. Measurements were made at baseline and repeated after 1 and 6 hours of two randomized periods of 6 hours of PP with one of two support types: conventional foam mattress or air-cushioned mattress. RESULTS: After logarithmic transformation of the data, an analysis of variance (ANOVA) showed that IAP and PDRICG were significantly influenced by the type of support during PP with an increase in IAP (P < 0.05 by ANOVA) and a decrease in PDRICG on the foam mattress (P < 0.05 by ANOVA). Conversely, the measurements of EVLW did not show significant modification between the two supports whatever the posture. The ratio of the arterial oxygen tension to the fraction of inspired oxygen significantly increased in PP (P < 0.0001 by ANOVA) without any influence of the support. CONCLUSION: In comparison with a conventional foam mattress, the use of an air-cushioned mattress limited the increase in IAP and prevented the decrease in PDRICG related to PP in patients with ARDS. Conversely, the type of support did not influence EVLW or oxygenation.

Adult↗

Interface pressure measurement during surgery: a comparison of four operating table surfaces.

OBJECTIVE: To compare the pressure-reducing and pressure-redistributing characteristics of four operating room (OR) table mattresses using interface pressure measurements, in two positions adopted for surgical procedures. METHOD: Support surfaces were randomly assigned to 80 patients. These were: an overlay pad filled with fibres (the standard OR mattress), a custom-made viscoelastic polyurethane foam mattress, an inflatable mattress with air-filled cells and a fluid mattress. An XSENSOR full-body pressure-mapping pad was used to record interface pressures of 40 patients in the supine position and 40 patients in the lithotomy position. Measurements were analysed for peak pressure, peak pressure index, total contact surface area and the occurrence of a significant increase in interface pressure during the surgical procedure. RESULTS: The highest interface pressures were measured on the standard mattress, in both the supine and lithotomy position. Overall, the fluid mattress showed the best pressure-reducing and pressure-redistributing capacities. CONCLUSION: As long as no reference values are available for interface pressures under which no pressure-related damage will occur, clinical testing of OR table surfaces is still necessary.

Beds↗