Effect of seated posture on interface pressure in children who are able-bodied and who have myelomeningocele

PURPOSE: The objective of this study was to investigate the relationship between sitting position and interface pressure distribution in seated children. METHOD: Fifteen able-bodied children and 15 children with myelomeningocele complete paraplegia, aged 7 to 18 years were included in the study. The body-seat interface pressure was measured with the QA pressure measurement system. Four sitting positions typically used to reduce body-seat interface pressure position (recline, tilt, combined and lean forward) were compared to a neutral position. RESULTS: Test/re-test Pearson correlation coefficients were greater than 0.94 for maximum pressure and greater than 0.88 for mean pressure at all test positions (p < 0.0001) and, for the risk area (defined as the percentage of sensors which recorded pressures greater than 40 mm Hg.) varied from 0.62 to 0.85 (p < 0.0005). Maximum pressures for the myelomeningocele group were significantly higher than those recorded for able-bodied subjects in the neutral, combined and lean forward positions (p < 0.001). For the able-bodied subjects, maximum pressures at the combined (p < 0.001), tilt (p < 0.05) and lean forward (p < 0.0001) positions were significantly lower than those measured at the neutral position. For the myelomeningocele subjects, maximum pressure at all tested positions was significantly lower than at the neutral position (p < 0.05). CONCLUSIONS: The results point to the importance of measuring body-seat interface pressure for each wheelchair user and of using the information to customize wheelchair utilization.     

Effect of seated posture on interface pressure in children who are able-bodied and who have myelomeningocele

Purpose : The objective of this study was to investigate the relationship between sitting position and interface pressure distribution in seated children. Method : Fifteen able-bodied children and 15 children with myelomeningocele complete paraplegia, aged 7 to 18 years were included in the study. The body-seat interface pressure was measured with the QA pressure measurement system. Four sitting positions typically used to reduce body-seat interface pressure position (recline, tilt, combined and lean forward) were compared to a neutral position. Results : Test/re-test Pearson correlation coefficients were greater than 0.94 for maximum pressure and greater than 0.88 for mean pressure at all test positions ( p < 0.0001) and, for the risk area (defined as the percentage of sensors which recorded pressures greater than 40 mm Hg.) varied from 0.62 to 0.85 ( p < 0.0005). Maximum pressures for the myelomeningocele group were significantly higher than those recorded for ablebodied subjects in the neutral, combined and lean forward positions ( p < 0.001). For the able-bodied subjects, maximum pressures at the combined ( p < 0.001), tilt ( p < 0.05) and lean forward ( p < 0.0001) positions were significantly lower than those measured at the neutral position. For the myelomeningocele subjects, maximum pressure at all tested positions was significantly lower than at the neutral position ( p < 0.05). Conclusions : The results point to the importance of measuring body-seat interface pressure for each wheelchair user and of using the information to customize wheelchair utilization.     

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.     

Reliability of bench tests of interface pressure

Determination of an appropriate wheelchair cushion to optimize loading on buttock tissue is crucial to pressure ulcer prevention. Standardized test methods aim to simplify selection by helping clinicians and users identify a class or category of cushions that will meet the important medical need of adequate pressure distribution. The objective of this project was to determine the test-retest reliability of interface pressure measurements taken using bench tests as opposed to human subject tests. Ten wheelchair cushions were tested following the methods for interface pressure measurement as defined in a draft International Organization for Standardization document. Dispersion index, contact area, percent force in the ischial regions, peak pressure index, and seating pressure index-standard deviation are reliable measures. Average pressure is reliable but not very volatile between cushions. The data also indicate that peak pressure, seating pressure index-skew (SPI-sk), and the other five percent force regions are not reliable. Certain bench interface pressure variables were found to have adequate intralaboratory repeatability. Interlaboratory reliability must also be tested. If a bench interface pressure test is used to indicate cushion performance, its validity should also be studied. Research is underway to relate interface pressure variables to clinical measurements of wheelchair users. Once validity is shown, standardized test results can then be used by clinicians to simplify and improve the wheelchair cushion selection process.     

Continuous monitoring of interface pressure distribution in intensive care patients for pressure ulcer prevention

Title.  Continuous monitoring of interface pressure distribution in intensive care patients for pressure ulcer prevention.
Aim.  This paper is a report of a study conducted to examine whether continuous interface pressure monitoring of postoperative patients in an intensive care unit is feasible in clinical practice.
Background.  The interface pressure between skin and surfaces is generally evaluated for pressure ulcer prevention. However, the intensity and duration of interface pressure necessary for pressure ulcer development remains unclear because the conventional interface pressure sensors are unsuitable for continuous monitoring in clinical settings.
Methods.  A total of 30 postoperative patients in an intensive care unit participated in this study in 2006–2007. A sensor was built into a thermoelastic polymer mattress. The whole-body interface pressure was recorded for up to 48 hours. Pressure ulcer development was observed during the morning bed-bath. For analysis, the intensity and duration of the maximal interface pressure was evaluated.
Findings.  The mean age of the study group was 62·0 ± 15·4 years. Two participants developed stage I pressure ulcer and blanchable redness at the sacrum. The longest duration of pressures greater than 100 mmHg were 487·0, 273·5 and 275·7 minutes in the pressure ulcer, blanchable redness and no redness groups respectively.
Conclusion.  Continuous monitoring of the intensity and duration of whole-body interface pressure using the KINOTEX sensor is feasible in intensive care patients.     

The relationship between pressure ulcer incidence and buttock-seat cushion interface pressure in at-risk elderly wheelchair users

OBJECTIVE: To investigate the relation between pressure ulcer incidence and buttock-wheelchair seat cushion interface pressure measurements. DESIGN: Secondary analysis of data from a randomized clinical trial. SETTING: Skilled nursing facility. PATIENTS: Thirty-two elderly patients (age, > or = 65 yr), with Braden score < or = 18 and Braden mobility and activity subscale score < or = 5, who used wheelchairs > or = 6 hr/d, were free of existing sitting-induced pressure ulcers, and weighed < or = 250 lb. INTERVENTIONS: Generic foam seat cushion or pressure-reducing seat cushion. MAIN OUTCOME MEASURES: The incidence of sitting-induced pressure ulcers over a 1- to 12-month period was compared with pressure measured between patients' buttocks and wheelchair seat cushions. A flexible pad with a 15 x 15 pressure sensor array was used to measure interface pressure. RESULTS: Interface pressure measured on wheelchair seat cushions was higher (p < or = .01 for both peak pressure and average of highest 4 pressures) for patients who developed sitting-acquired pressure ulcers compared with those patients who did not. CONCLUSIONS: Results indicated that higher interface pressure measurements are associated with a higher incidence of sitting-acquired pressure ulcers for high-risk elderly people who use wheelchairs.     

Assessment of Visual Acuity in the Supine Position

Objective: To determine whether a modified Snellen eye chart could be used to accurately assess visual acuity (VA) in the supine position.
Method: This was a prospective study involving ED staff volunteers comparing VA on a standard Snellen eye chart with VA on a size-reduced ceiling-mounted modified Snellen eye chart.
Results: Fifty-six volunteers participated. VA ranged from 20/10 to 20/200 on both of the cham, but 87% of the volunteers had VA of 20/50 or better. The VA results for the 2 charts were highly correlated; right eye r = 0.931 and left eye r = 0.953. Weighted ks showed substantial agreement for both eyes; k = 0.63 and 0.79 for the right and left eyes, respectively. In only 4 of 112 paired measurements did the VA recorded with the ceiling chart differ by >1 line from that recorded on the Snellen chart.
Conclusion: There is an excellent correlation between VAs determined in the erect and the supine positions using the standard Snellen eye chart and the modified ceiling-mounted version. Substantial agreement exists between readings using the 2 charts. Although, additional testing is warranted in an ophthalmologically diverse patient population, use of this chart for the assessment of VA in the supine ED patient may allow for earlier VA evaluation.     

Evaluation of transducer performance for buttock-cushion interface pressure measurements

To assess the performance of transducers used clinically to measure pressure at the skin-cushion interface of seated patients, transducers were placed between slabs of gel and/or foam materials compressed between platens. The recorded pressures consistently exceeded the nominal pressures calculated using the surface area of the slabs. This overestimation, observed in both miniature diaphragm transducers and air cell transducers, appeared to result from preferential loading of the transducer due to insufficient structural compliance in the environs. On the other hand, air cell transducers placed at a skin-foam interface beneath the thighs of human subjects gave readings which agreed closely with subcutaneous tissue pressure measurements obtained from a wick catheter inserted at the same location. These results suggest that, although pressure measurements are prone to error due to load sharing, results obtained clinically from subjects on soft cushions are reasonably accurate because of the high compliance of human soft tissue and the foam. Under low loads these distribute the pressure equitably and avoid concentrations of load on the transducer.     

High blood pressure in children and adolescents

High blood pressure in children and adolescents is a growing health problem that is often overlooked by physicians. Normal blood pressure values for children and adolescents are based on age, sex, and height, and are available in standardized tables. Prehypertension is defined as a blood pressure in at least the 90th percentile, but less than the 95th percentile, for age, sex, and height, or a measurement of 120/80 mm Hg or greater. Hypertension is defined as blood pressure in the 95th percentile or greater. A secondary etiology of hypertension is much more likely in children than in adults, with renal parenchymal disease and renovascular disease being the most common. Overweight and obesity are strongly correlated with primary hypertension in children. A history and physical examination are needed for all children with newly diagnosed hypertension to help rule out underlying medical disorders. Children with hypertension should also be screened for other risk factors for cardiovascular disease, including diabetes mellitus and hyperlipidemia, and should be evaluated for target organ damage with a retinal examination and echocardiography. Hypertension in children is treated with lifestyle changes, including weight loss for those who are overweight or obese; a healthy, low-sodium diet; regular physical activity; and avoidance of tobacco and alcohol. Children with symptomatic hypertension, secondary hypertension, target organ damage, diabetes, or persistent hypertension despite nonpharmacologic measures should be treated with antihypertensive medications. Thiazide diuretics, angiotensin-converting enzyme inhibitors, angiotensin II receptor blockers, beta blockers, and calcium channel blockers are safe, effective, and well tolerated in children.     

Nebulizer therapy for children: the device-patient interface

A therapeutic aerosol benefits the patient only if the medication deposits in the airway. Advances in nebulizer design have made them more efficient and "user friendly," but the greatest problem with administering aerosolized medication continues to be educating patients and caregivers to use aerosol devices properly and consistently. Misuse and nonuse are the greatest impediments to effective aerosol delivery. The respiratory pattern and degree of patient cooperation also profoundly affect aerosol deposition, and those effects are greatly magnified in small children. There are many misconceptions about nebulizer use and nebulizer equipment, even in teaching hospitals, and these can have serious consequences when patients do not receive the medication they need. This review discusses how airway physiology, nebulizer technology, and patient education relate to appropriate nebulizer use. Education is critically important, but unfortunately it is often a misunderstood or neglected part of aerosol administration.     

去枕仰卧位用于颈椎病变核磁共振检查的效果观察

目的去枕仰卧位用于颈椎病变核磁共振检查的效果观察。方法选取我院2012年3月²014年1月收治的81例颈椎病患者的临床资料,随机将患者分为去枕仰卧位组、平卧位组与前屈位组各27例,比较三组患者的成像效果与体位满意度。去枕仰卧位组患者的椎体不稳、椎管狭窄、颈椎间盘突出检出率最高,明显高于其他两组,对比差异显著,具有统计学意义(P<0.05)。结果去枕仰卧位患者成像满意、较满意与不满意比例分别为74.1%、22.8%、3.7%,总满意度为96.3%,明显优于其他两组,对比存在较大差异,具有统计学意义(P<0.05)。三组患者在体位满意度上对比差异显著,具有统计学意义(P>0.05)。结论患者取平卧位,可获取更好的成像效果,因此,在颈椎病变核磁共振检查中,取平卧位最佳。     

Electrical muscle stimulation for pressure variation at the seating interface

A new method is proposed for pressure sore prevention using electrical muscle stimulation (EMS). Potential mechanisms through which EMS may act for this purpose are discussed, including both short-term/dynamic and chronic effects. Measurements of maximum pressure variation in three able-bodied subjects using low levels of stimulation were performed. Pressure distribution changes were also measured. Fatigue effects on pressure redistribution were studied for four able-bodied subjects as well as for one C4, complete spinal cord injured individual. The results indicate that EMS produces sizeable pressure reduction under the ischial tuberosity, with redistribution occurring over other parts of the seating surface in able-bodied subjects. Fatigue effects were not observed in the four able-bodied subjects even after prolonged stimulation. Fatigue was observed with the spinal cord injured subject, but only after extensive stimulation. These studies demonstrate the feasibility of using EMS at relatively low intensity to vary seating interface pressure. The results warrant continued investigation of EMS to assist in pressure sore prevention.     

The effect of a double-regression hospital bed on interface pressure

This study examines, for the first time, the differences of interface pressure in different positions on a standard hospital bed and a double-regression hospital bed. For both beds, the interface pressure was recorded in four supine positions and three lateral positions in 49 healthy volunteers (30 men and 19 women). The results demonstrate, independently of the bed type, that when a supine and lateral position is indicated, the 0° and 30° positions, respectively, are preferable. We also show that patients requiring prolonged upper body elevation may benefit from the use of a double-regression hospital bed that reduces the maximum pressure and the pressure surface greater than 32 mm Hg at the sacrum and heel sites.