Factors affecting the pressure-distributing properties of foam mattress overlays

A universal concern of those in nursing care is the occurrence of decubitus ulcers. To minimize this problem foam overlays are routinely used on hospital beds throughout the country. This study was undertaken to develop laboratory testing procedures which will reliably predict the support characteristics of mattress overlays in clinical service. Initially, test methods based on constant load and constant deformation boundary conditions were developed. These methods were applied to measure the pressure-distributing properties of 10 polyurethane foams fabricated in a wide range of pliancies and densities. Based on these laboratory data, a single index was developed to express the effectiveness of each overlay in distributing interface pressures. This index was found to be influenced by the stiffness (ILD), density, and thickness of each device. These data were then compared with measurements of interface pressure obtained from volunteer subjects who were supported on mattress overlays fabricated from each of the original foams. Correlation of these data with the laboratory results demonstrated that the effectiveness index was an accurate predictor of mattress overlay performance under end-use conditions.     

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.     

The role of alternating air and Silicore overlays in preventing decubitus ulcers

Patients with chronic neurological diseases who were at high risk of decubitus ulcers were randomly assigned to alternating air on silicore mattress overlays for a period of 3 months. Of 148 subjects who completed the trial, more than 50% in each group developed one or more ulcers. No statistically significant differences between groups were found in the incidence, severity, healing duration or the location of the ulcers; with the exception of a significant difference (p less than 0.001) in the categorical location of the trochanters.     

Effects of position and mattress overlay on sacral and heel pressures in a clinical population.

A comparison of pressure reducing properties of alternating air, static air, and water mattress overlays was conducted with 57 patients in a surgical intensive care unit. Sacral and heel pressures in both recumbent and semi-Fowler's positions were tested for each surface using a repeated measures design. Mean pressures for the alternating air mattress were significantly higher than pressures with other surfaces, regardless of position or site. There were significant main effects for position and site, with higher pressures in the semi-Fowler's position and at the sacral site. A significant interaction between surface, site, and position was found. Pressure sores developed in eight patients, but the incidence was not significantly different across groups. A pressure measuring device constructed from available clinical materials proved to be both sensitive and reliable. The findings suggest alternating air overlays should be avoided, and that positioning and periodic position change to reduce sacral pressures for patients requiring prolonged upper body elevation is important.     

Supine interface pressure in children

The effectiveness of using 2-inch and 4-inch convoluted foam overlays to protect children from developing pressure sores was investigated in 13 healthy children ranging in age from ten weeks to 13.5 years. Interface pressures were measured under the occipital, sacral, and scapular areas of children as they lay on a standard mattress, then on 2-inch and 4-inch foam overlays. The differences in pressures between the occiput and scapula, occiput and sacrum, and scapula and sacrum were significant (p less than .001), with the highest pressures recorded under the occipital area. Occipital pressures decreased from 45.7mmHg on the standard mattress to 22.3mmHg on the 4-inch overlay in ages 0 to 2, 54.3mmHg to 30.5mmHg in ages 2 to 10, and 78.0mmHg to 42.4mmHg in ages 10 to 14. Sacral pressures were highest in older and larger children, increasing from 17mm Hg in ages 0 to 2 to 34mmHg in ages 10 to 14, and when body surface area was greater than 1m2. These results indicate that the site of greatest pressure changes with increasing age from the occipital area to the sacral area. Therefore, different pressure relief considerations are necessary in treating pediatric patients than in managing pressure under adults.     

Costs and acceptability of two special overlays for the prevention of pressure sores

In a randomized clinical trial, 187 adult patients with chronic neurologic conditions who were at a high risk of developing pressure sores were assigned for 3 months to either an alternating air (AA) mattress overlay or a silicore (S) mattress overlay. Costs associated with each overlay were calculated and compared by adding depreciation and yearly expenses related to maintenance, operation, and repair for 148 patients who completed the trial. Acceptability was measured by questionnaires and interviews involving 45 of the patients' primary nurses and a sample of 40 patients (20 from each overlay group). The annual cost of the AA overlay was 54% more than that of the S overlay. Although most nurses (more than 74%) believed that both overlays helped prevent pressure sores and deter their progression, many (more than 56%) would not recommend either type to other facilities or to patients at home due to specific negative features. Implications for manufacturers, investigators, clinicians, and administrators are identified.     

A review of pressure reduction device studies.

When considering patient morbidity, mortality and costs, pressure sore formation is a major health care concern. An adjunct to the nursing care plan for prevention and treatment is the selection of a pressure reduction/relief device. This review of four pressure reduction device studies is intended to increase the vascular nurse's knowledge base concerning pressure reduction device efficacy. Each study is reviewed and graphed to identify like patterns within each study. Foam is judged to be least effective. Air cell and air mattress overlays are found to be intermediate devices and the low air loss beds appear to be the most effective. Few of the tested devices reduced pressure below 32mmHg at the heel site, leaving the heel at risk for breakdown.     

Respiratory effects of spinal immobillzatlon

Objective. To evaluate the effect of whole-body spinal immobilization on respiration. Methods. This was a randomized, crossover laboratory study with 39 human volunteer subjects (20 males; 19 females) ranging in age from 7 to 85 years. Respiratory function was measured three times: at baseline (seated or lying), immobilized with a Philadelphia collar on a hard wooden backboard, and on a Scandinavian vacuum mattress with a vacuum collar. The comfort levels of each of the two methods were assessed on a forced Likert scale. Results. Both immobilization methods restricted respiration, 15% on the average. The effects were similar under the two immobilization conditions, although the FEV, was lower on the vacuum mattress. Respiratory restriction was more pronounced at the extremes of age. The vacuum mattress was significantly more comfortable. Conclusion. This study confirmed the previously reported respiratory restriction caused by spinal immobilization. Vacuum mattresses are more comfortable than wooden backboards.     

The user--friendliness of protective support surfaces in prevention of pressure sores

Special mattress overlays and seat cushions for the prevention of pressure sores constitute a large portion of the rehabilitation products market. Consumers frequently face economic concerns in choosing among these products. This article summarizes the favorable and unfavorable features of major support surface types: foam, air-filled, flotation, and alternating air. A careful consideration of characteristics, such as fire safety, patient comfort, and ease of transfer and handling, may facilitate selection and result in more satisfied users and caregivers.     

A review of the Medical Agency Services Confor-Med range

Medical Agency Services Ltd (MAS) has, since 1994, been involved in the design and development of mattresses and overlays manufactured from visco-elastic polymer foam, which is currently utilized in the manufacture of domestic, automative and specialist bedding and seating products. The foam is fire retardant and satisfies the BS 5852 (Part 2) ignition source 5. The foam is a heat and weight sensitive, visco-elastic polymer, giving a high performance, pressure redistributing surface that 'moulds' to the patient giving simultaneous muscular/skeletal support and allowing the patient to feel comfortable. The Confor-Med mattress offers a sensible alternative for patients with high Waterlow scores who have no pressure sores, but require early intervention to prevent pressure sores developing. A case study is included in this review of the products.     

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.     

Evaluating two dynamic mattresses in a nursing home setting

A formal, ethically approved, prospective product evaluation was undertaken in a nursing home setting. The aim of the study was to generate patient-focused clinical outcome data in a 'real world' setting to support use of the dynamic Sidhil Plus (mattress replacement) and Solo (mattress overlay) for patients who were at an elevated risk of pressure ulcers. The primary outcome was for patients to remain free from additional pressure damage while the products were in use. Secondary outcomes of interest included patient and carer views of the product. The results reported here indicate that for this client group these 'low tech' products perform well. Of the 22 residents taking part, two developed pressure damage during the trial, however the position of the pressure damage indicated that the cause was most likely not the mattress.     

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.     

The mattress sutures: vertical,horizontal, and corner stitch

The interrupted vertical and horizontal mattress suture techniques are two of the most commonly used skin closure methods. These mattress sutures promote wound edge eversion and less prominent scarring. Vertical and horizontal mattress sutures allow for skin edges to be closed under tension when wound edges have to be brought together over a distance. The corner stitch, a variation of the horizontal mattress suture, is commonly used for closure of angled skin flaps or wounds. Although mattress sutures can produce surface scarring or "railroad marks," early removal of these sutures can limit this damage.     

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.     

动态与静态空气床垫预防神经内科卧床患者压疮效果的比较

目的比较静态空气床垫与动态空气床垫对预防神经内科卧床患者压疮发生的效果。方法便利选取2012年5-8月南京军区南京总医院的神经内科患者90例,根据随机数字表法分为静态空气床垫组和动态空气床垫组各45例,两组均每2h翻身1次,预期观察14d,比较两组患者的压疮发生率、压疮严重度、Braden压疮危险评估结果及成本效益。结果两组患者观察期内压疮发生率均为0;Braden压疮危险评估结果分别为(14.45±2.07)分和(14.25±2.49)分,差异无统计学意义(P0.05);静态空气床垫价格比动态空气床垫价格低350元,且无医疗耗电;静态空气床垫和动态空气床垫的平均护理时间分别为(8.87±3.03)、(9.00±3.10)d,平均每人翻身次数分别为(108±37.16)、(106±36.33)次,差异均无统计学意义(P0.05)。结论静态空气床垫与动态空气床垫比较,其预防压疮的效果相当,但成本投入少于动态空气床垫。     

POTENTIAL FOR BED SORES DUE TO HIGH PRESSURES : INFLUENCE OF BODY SITES,BODY POSITION,AND MATTRESS DESIGN

SUMMARY Pressures were measured on 10 subjects, supine and sitting, under six anatomical sites prone to bed sores on three different mattresses. Studied were the Clinifloat and Therarest specialist replacement mattresses, and a standard hospital mattress. Mean supine pressures were less than 5 kPa under four sites. Average supine buttock pressure was 2.93 kPa. Occiput and heel pressures were much higher than under other sites, being on average 2.6 and 4.5 times greater respectively than the mean buttock pressure. On sitting up, buttock pressure increased by a factor of 1.7 on average, to a level higher than the accepted capillary closing pressure. Measurements were consistent with mattress design, specific features of which can significantly affect pressure under certain sites.     

Clinical evaluation of an electronic pressure-relieving mattress

A 12-month clinical evaluation of the Talley Quattro Deep Cell 2000 mattress manufactured by Talley Medical was undertaken on both a trauma and surgical ward at the Royal Devon and Exeter Hospital. An identified registered nurse coordinated the evaluation with support from tissue viability clinical nurse specialists. Data on patients, including diagnosis, Waterlow score, pressure area condition and general comments by nurses and patients, were collected. The evaluation involved 35 patients who were at high- to very-high risk of pressure sore formation. The results showed that 16 out of 40 sores healed during the evaluation period and 16 sores remained unchanged. Only one patient developed broken skin while nursed on the mattress. Seventeen patients maintained tissue integrity. Although the study was limited the results suggest that the Talley Quattro Deep Cell 2000 mattress is useful in preventing and managing pressure sores in high- to very high-risk patients.     

The effect of various combinations of turning and pressure reducing devices on the incidence of pressure ulcers

BACKGROUND: Turning is considered to be an effective way of preventing pressure ulcers, however almost no research has been undertaken on this method. AIM: The aim of the study was to investigate the effect of four different preventative regimes involving either frequent turning (2, 3 hourly) or the use of a pressure-reducing mattress in combination with less frequent turning (4, 6 hourly). SUBJECTS: 838 geriatric nursing home patients participated in the study. METHODS: During 28 days, four different turning schemes were used: turning every 2 h on a standard institutional (SI) mattress (n = 65), turning every 3 h on a SI mattress (n = 65), turning every 4 h on a viscoelastic foam (VE) mattress (n = 67), and turning every 6h on a VE mattress (n = 65). The remaining patients (n = 576) received standard preventive care. MAIN RESULTS: The incidence of non-blanchable erythema (34.8-38.1%) was not different between the groups. The incidence of grade II and higher pressure ulcers in the 4h interval group was 3.0%, compared with incidence figures in the other groups varying between 14.3% and 24.1%. CONCLUSIONS: Turning every 4 h on a VE mattress resulted in a significant reduction in the number of pressure ulcer lesions and makes turning a feasible preventive method in terms of effort and cost.     

两种床垫对非特异性腰痛影响的双盲研究

目的：比较独立袋装弹簧床垫与硬弹簧床垫对非特异性腰痛的影响。方法：非特异性腰痛患者12例,分别选用独立袋装弹簧床垫（A组）与硬弹簧床垫（B组）作为常规睡眠床进行随机双盲对照研究。2组分别于实验前及实验后1及3周时进行改良Oswestry腰痛问卷、腰部活动度、腰痛VAS及仰卧位腰部压力检测。结果：不同时间点2组改良Oswestry腰痛问卷、腰部活动度及腰痛VAS检测与实验前比较均差异无统计学意义;2组间比较亦无统计学意义。但仰卧位腰部压力检测,A组明显高于B组（P〈0.01）。结论：短期使用独立袋装弹簧床垫与硬弹簧床垫后对非特异性腰痛患者的疼痛症状、功能及腰部活动度的改善无明显作用,但独立袋装弹簧床垫对承托腰部有较好作用,可维持腰部正常生理曲线。