Variation in Leg Tissue Dielectric Constant Values of Healthy Young Adult Females With and Without Compression Bandaging

Background The clinical efficacy of a compression application has been often limited to the assessment of the change in limb volume, change in clinical symptoms (i.e., wound size, pain, range of motion, incidence of cellulitis), or vascular hemodynamics of the whole limb. Assessing compression-related biophysical changes of a localized area, such as around a wound, or in an area outside of an extremity cannot be objectively assessed by these measurements. Tissue dielectric constant (TDC) values, which provide a measure of the local tissue water (LTW) content, offer an alternative method to document variation in the LTW content of the skin in a specific location. The goals of the present research were (1) to characterize TDC values, expressed as percentage tissue water, from multiple areas along the medial aspect of the lower leg of healthy volunteers and (2) to explore the potential utilization of the TDC values to assess change in tissue water content in a localized area following compression applications. Methods TDC was measured at 10, 20, 30, and 40 cm proximal to the medial malleolus on the medial aspect of the right leg of 18 young adult healthy women with an age range of 18-23 years and a body mass index of 18.7 to 30.7kg/m^2.. TDC was measured at baseline and after 10 minutes of exercise with compression in place on three separate days during which three different compression applications were assessed: a longitudinal elastic stockinette, a two-layer cohesive compression kit, and a combination of the two. Leg circumferences and compression-related interface pressures were also measured. Results Test-Retest Reliability of circumferential measurements and TDC values evaluated using Intraclass correlation coefficient (ICC _3,1) revealed excellent and moderate-to-good reliability, respectively. Analysis of TDC values along the length of the limb using Friedman's test, revealed a small but statistically significant overall difference among baseline TDC values attributable to a smaller value at 40 cm. The largest difference in cumulative average was 7.7% which occurred between 20 and 40 cm, with all other differences between locations less than 1%. No significant differences between the compression applications were observed. Conclusion  The present findings demonstrate the utility of TDC measurements as a modality to assess compression-related changes in the legs of healthy women as a foundation for their potential use in assessing outcomes of compression treatments for persons with lower extremity edema or lymphedema. The absence of a significant change in TDC values in these healthy non-edematous conditions and the demonstrated reliability of the TDC measurements on three different days provides further support for the utility of such applications of TDC measurements. The extension to patients with lower extremity edema or lymphedema needs to be evaluated.

Textile composition, not number of layers, impacts interphase pressure and static stiffness index: A pragmatic, comparative analysis of the in vivo interphase pressure of 7 different 2-layer cohesive bandage kits in healthy volunteers

"OBJECTIVE: The aim of the study was to comparatively evaluate the in vivo interphase pressure (IP) and statis stiffness index (SSI), upon initial application, of 7, 2-layer cohesive bandage kits when applied on healthy volunteers.

METHOD

Bandages were applied in random order, on non-consecutive days by a single experienced clinician. The IP at the time of application was measured on the right lower limb of 10 healthy volunteers at 2 different points (B1, C). Measurements were made in 2 positions, supine and standing. There were 2 consecutive applications and measurements made for each compression bandage set. Statistical analysis of the outcome data was performed, utilizing a repeated measures analysis of variance (ANOVA) to determine: the effects of the bandage type on IP and SSI for each of the measurement points and according to the subject's position. Post hoc analyses were performed by Tukey and Bonferroni test to identify significant differences. The dispersion of the recorded pressures within the study population (dispersion between subjects) was assessed by the coefficient of variations.

RESULTS

The in vivo IP measured at B1 in the supine position varied from 50.1 mmHg (±5.3) to 73.7 mmHg (±13.4). The in vivo IP measured at C in the supine position varied from 53.2 mmHg (±7.6) to 69.3 mmHg (±10.6). Bonferroni post hoc analyses demonstrated with a 95% confidence interval, there was a significant difference between wraps and placed them into 5 groups for the IP measured at B1, and 3 groups for measurements taken at C. A regression model including the main effects of the wrap and the subject with their interaction were similar for the IP observed at B1 and C in the supine position (r2 = 0.881). The in vivo SSI measured at B1 varied from 11.95 (±5.4) to 6.65 (±4.4). Post hoc analyses similarly demonstrated significant differences placing the wraps into 3 different groups. Statistical analysis of the variability of the IP observed at B1 and C showed there was a significant difference at B1 (P = .001), which was not observed at C (P = .347).

CONCLUSION

Sub-bandage pressure measurements produced by the 7, '2-layer cohesive' compression box sets were not equivocal. IP and SSI varied by textile composition, clinically supporting the trial of alternative '2-layer cohesive' compression box set if the desired outcome (ie, wound healing, edema reduction) is not achieved. Additional study in patients with edema is warranted to allow an evidenced-based approached to the selection of a compression bandage set.

Selecting appropriate compression for lymphedema patients: American Vein and Lymphatic Society position statement

BACKGROUND

Lymphedema is a significant and disabling disorder affecting millions of people worldwide. Compression therapy is an important component of lifelong treatment but the specifics of appropriate compression garment selection and prescribing is not always well understood by practitioners and payers.

METHOD

An expert panel of the American Vein and Lymphatic Society was convened to write a Position Statement with explanations and recommendations for the appropriate compression therapy to be used in the treatment of lymphedema patients.

RESULT

A Position Statement was produced by the expert panel with recommendations for documentation and compression therapy treatment. Their recommendations were reviewed, edited, and approved by the Guidelines Committee of the society.

CONCLUSION

This societal Position Statement provides a useful document for reference for medical care providers for the appropriate compression therapy selection and treatment of patients with lymphedema.

Experimental Simulation Study to Assess Pressure Distribution of Different Compression Applications Applied Over an Innovative Primary Wound Dressing

INTRODUCTION

Compression is integral to the management of edema and the prevention of venous leg ulcers (VLUs).

OBJECTIVE

The aim of this study is to assess the sub-bandage pressure distribution under 3 compression applications as well as to assess the impact of an innovative primary wound dressing, applied under the compression products, on pressure distribution.

MATERIALS AND METHODS

A series of controlled tests were performed using a simulated leg model (SLM). A pressure mapping sensor and system software was used to measure the interface pressure (IP) and pressure distribution created by the application of 3 different compression systems with and without the addition of an elastic longitudinal stockinette (fuzzy wale compression; FWC). These included: (1) 2-layer cohesive wrap; (2) 3-layer compression application; and (3) 4-layer compression application. The IP was pressure between the SLM and the innovative dressing over which the compression applications were applied. Seven different configurations were tested, including the compression applications alone and in combination with the FWC. In addition to the IP measurements, pressure mapping visualizations were captured with the pressure mapping sensor and system software. A custom MATLAB program was written for data analysis, differentiations in discrete high- and low-pressure locations across the compressed area, and graphing of the pressure readings.

RESULTS

The overall average pressure for each testing setup without FWC ranged from 34.65 ± 4.84 mm Hg for the 2L configuration to 63.92 ± 7.08 mm Hg for the 4L configuration. The addition of the FWC resulted in a 19% increase for the 2L, 9% increase for the 3L, and 7% increase for the 4L compression systems. Additionally, it was noted that the inclusion of FWC resulted in a significant change in pressures vertically oriented under the 2-, 3-, and 4-layer compression applications of 34.52 ± 9.06 mm Hg, 99.21 ± 29.81 mm Hg, and 128.96 ± 22.97 mm Hg, respectively. The pressure distribution under the compression alone was observed to be largely uniform except for areas of overlap that produce horizontal bands of elevated pressures. The presence of the primary wound dressing did not have a significant impact on the IP measurements. The addition of FWC to all compression applications demonstrated a vertical distribution of compression along the sensor with alternating areas of little or no compression.

CONCLUSIONS

The unique alternating pressure distribution observed in the in vitro pressure testing with the use of FWC in a clinical setting has been observed to produce better edema management and wound edge migration that mirrors the vertical pressure distribution observed in the study. Additional in vitro and in vivo research to evaluate the biophysical impact of IP created by the use of a combination of primary wound dressings and compression applications with focus on the total pressure and the distribution across the surface of intact tissue and open wound bed is warranted.

A dual compression system: preliminary clinical insights from the US

There is growing evidence on an interconnection between the venous and lymphatic systems in venous leg ulceration, and the possible effects of prolonged oedema and lymphatic impairment in delayed wound healing. Compression therapy is a widely accepted treatment for venous and lymphatic disorders, as it decreases recurrence rates and prolongs the interval between recurrences. Compression bandages improve venous return, increase the volume and rate of venous flow, reduce oedema and stimulate anti-inflammatory processes. The pressure at the interface (IP) of the bandage and the skin is related to the elastic recoil of the product used and its resistance to expansion. The pressure difference between the IP in the supine and standing positions is called the static stiffness index (SSI). Elastic materials provide little resistance to muscle expansion during physical activity, resulting in small pressure differences between resting and activity, with an SSI <10mmHg. Stiff, inelastic materials with a stretch of <100% resist the increase of muscle volume during physical activity, producing higher peak pressures, an SSI of >10mmHg and a greater haemodynamic benefit than elastic systems. UrgoK2 is a novel dual-layer high-compression system consisting of an inelastic (short stretch) and elastic (long stretch) bandage, resulting in sustained tolerable resting pressure and elevated working pressures over extended wear times. It is indicated for the treatment of active venous leg ulcers and the reduction of chronic venous oedema. Each bandage layer has a visual aid to enable application at the correct pressure level. Published European studies have assessed this compression system, exploring its consistency of application, tolerability and efficacy. This article presents the first reports of health professionals' clinical experience of using the compression system in the US, where it has been recently launched. Initial feedback is promising.

Case report to demonstrate the need for selection criteria for optimal adjustable Velcro wrap prescription

Compression, in the form of either a compression bandage or a compression stocking, has been touted as the gold standard for treatment of swelling and venous leg ulcers (VLUs). Adjustable Velcro wraps have been marketed as compression alternative. Although there is a growing body of evidence to support use of these products, there has not been a critical evaluation of the functionality of the devices to best matching product to patient presentation and ability to use the device effectively. Unlike compression garments, which are classified by compression category (class I/II or flat knit/circular), there is not an algorithm to direct health professionals to best match a specific adjustable Velcro wrap to an individual patient presentation. This small case series demonstrates that although each product performed as marketed in vitro, performance in clinical setting varied greatly dependent on patient presentation and functional skill level.

S.T.R.I.D.E. Professional Guide to Compression Garment Selection for the Lower Extremity

The following supplement is a rare example of a paper that combines clinical experience and theoretical knowledge on textiles used in compression therapy. The authors' intention is to propose a decision support system for choosing specific compression devices, which can be adjusted to counteract the individual signs and symptoms in an optimally adopted way. The document concentrates on compression devices which can be self-applied by the patients—compression stockings and adjustable wraps. The acronym ‘S.T.R.I.D.E.’, incorporating both textile characteristics and clinical presentation, stands for: Shape, Texture, Refill, Issues, Dosage and Etiology. The intent of the mnemotechnical value is to highlight that successful compression includes more than dosage alone. In addition to dosage, etiology and patient presentation need to be incorporated, including a patient's physical ability to use compression effectively as part of the daily routine, thereby promoting adherence.

The suggested algorithms provide a valuable guide to stride across the important, but still underestimated field of medical compression therapy and will help to put the prescription of a specific product on a more rational basis. Enjoy reading!

Hugo Partsch Emeritus Professor Medical University of Vienna, Austria

Flow cytometric analysis of glucose transport by rat brain cells

The fluorescent, non-metabolizable glucose analog 6-[N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)amino]-6-deoxyglucose (NBDG) was used to measure rates of hexose transport by dissociated brain cells from developing and adult rats. Flow cytometric analysis of glucose uptake and expression of glucose transporters was performed by mapping on size by granularity, which discriminated between neurons and astrocytes in a suspension of mixed brain cells. These mapped cell populations were identified by immunofluorescent staining with antisera to neuron-specific enolase (NSE) and glial fibrillary acidic protein (GFAP). Specific uptake of the analog by membrane glucose transporters was confirmed by its inhibition by D-glucose and by cytochalasin B. Both neurons and astrocytes expressed the GLUT1 and GLUT3 transporter isoforms. This was confirmed by the additive inhibition of NBDG uptake by antibodies to these transporter isoforms in both cell types. The advantages of flow cytometric analysis of glucose transport include continuous monitoring over extremely short periods of time, increased precision of cell-by-cell flow cytometric measurements versus average uptake rates obtained with radioisotopes, and simultaneous analysis of uptake by different cell populations. Moreover, both uptake rates and the abundance of specific transporters can be determined directly and rapidly on the same cell suspension.

Effects of ethanol on GLUT1 protein and gene expression in rat astrocytes

Effects of ethanol on glucose transporter gene expression were examined in cultured rat astrocytes. Exposure to 50 or 100 mM ethanol for 18 hours significantly inhibited hexose uptake and reduced the number of glucose transporters, as indicated by binding studies with cytochalasin B. Indirect immunofluorescence and immunoperoxidase staining showed marked reduction of the GLUT1 glucose transporter by exposure to 100 mM ethanol for 5 or 18 hours, but no obvious change in response to 50 mM ethanol. Western blot analysis showed GLUT1 protein levels to be decreased by 52 +/- 12% (p < 0.05) after exposure to 100 mM ethanol for 18 hours. In situ hybridization histochemistry indicated an increase in steady-state GLUT1 mRNA in astrocytes exposed to 50 or 100 mM ethanol for 5 or 18 hours. Quantitation of GLUT1 mRNA levels by northern blot analysis showed that GLUT1 mRNA levels were increased by 59 and 112% in cells treated for 5 h with 50 and 100 mM ethanol, respectively. A similar effect was observed after treatment for 18 hours, but ethanol did not alter actin gene expression. Experiments using actinomycin D to block RNA synthesis suggest that this increase in steady-state mRNA level results from increased message stability. These results suggest that ethanol acts on GLUT1 gene expression at the post-transcriptional level.

Ethanol-induced changes in insulin-like growth factors and IGF gene expression in the fetal brain

Brain growth retardation is a major feature of the fetal alcohol syndrome (FAS). Insulin-like growth factors (IGF-I and IGF-II) have been shown to exert significant metabolic and growth-promoting effects. Previously, we showed that circulating levels of IGF-I as well as hepatic gene expression of both IGFs were decreased in newborn offspring of rats fed ethanol during pregnancy. This study investigated the effects of maternal ethanol ingestion on fetal rat brain growth and on levels of IGF-I and IGF-II, as well as their mRNAs, in fetal brain. IGF-binding protein (IGFBP) levels also were determined. Rats were fed 5% w/v ethanol in a liquid diet during gestation (EF group). Weight-matched animals were pair-fed equicaloric control diet (PF group) or were fed ad libitum (AF group). The mean fetal brain weight of EF offspring was 13% and 16% lower (P < 0.01) than that of PF and AF offspring, respectively. Body weight of EF pups was decreased to a greater extent, resulting in higher brain to body weight ratios in EF pups than in either control group (P < 0.05). IGF-I levels in EF pups decreased by 33% and 41% compared with the corresponding PF and AF values (P < 0.01). IGF-I mRNA levels decreased by 27% and 40% compared with PF and AF values, respectively. A positive correlation was observed between brain IGF-I level and brain weight (r = 0.561, P < 0.01). IGF-II levels were not affected despite a 50% decrease in IGF-II expression. In PF animals, the fetal brain IGF-I and IGF-II mRNA levels were reduced by 28% and 21%, apparently in response to undernutrition. IGF-binding proteins levels were low in the EF group but not statistically significant compared with control values. The diminished fetal brain concentration of IGF-I and decreased gene expression of IGFs may play a role in brain growth retardation associated with FAS.

Ethanol and glucose-deprivation neurotoxicity in cortical cell cultures

The toxic effects of ethanol on rat cortical cell cultures were compared with neuronal damage induced by glucose deprivation. Exposure to decreased glucose concentrations produced dose-dependent neuronal injury, as indicated by the release of lactate dehydrogenase (LDH) into the culture medium. Complete glucose deprivation resulted in mean LDH release that was more than 60% greater than that from sister cultures incubated in the presence of 5.5 mmol/L glucose. Exposure to ethanol (25, 50, or 100 mmol/L) similarly resulted in dose-related LDH release. The degree of injury resulting from complete glucose deprivation or 100 mmol/L ethanol approximated that produced by exposure to 100 mmol/L glutamic acid. Ethanol did not significantly alter LDH release from cultures consisting of only astrocytes. Both effects were inhibited by the N-methyl-D-aspartate (NMDA) receptor antagonist, D,L-2-amino-5-phosphonovaleric acid (APV). Glutamate levels were increased in the culture medium to 191% +/- 8% of the control value after glucose deprivation (P < .001) and to 186% +/- 16% after exposure to 100 mmol/L ethanol (P < .01). 3H-glutamate uptake by cultured astrocytes was reduced by glucose deprivation and by ethanol. This range of ethanol concentrations has previously been shown to inhibit hexose uptake by cultured astrocytes. The present results suggest that decreased glucose uptake by astrocytes in the presence of ethanol impairs their uptake of glutamate, which contributes to excitotoxic neuronal injury.

Insulin-like growth factors (IGF-I and IGF-II), IGF-binding proteins, and IGF gene expression in the offspring of ethanol-fed rats

Insulin-like growth factors I and II (IGF-I, IGF-II) and IGF-binding proteins (IGBPs) are important modulators of fetal growth. Fetal growth retardation is a major component of the fetal alcohol syndrome, which is associated with maternal alcoholism. This study examined the relationship of IGF-system components to growth retardation induced by ethanol in fetuses of rats fed equicaloric liquid diets (AF, ad libitum-fed controls; PF, pair-fed controls; EF, ethanol-fed) during gestation. The gene expression of IGF-I and IGF-II in fetal liver and the concentration of IGFs and IGFBPs in serum and liver were determined. The mean weight of EF fetuses was 13% and 16% less (p < 0.01) than that of PF and AF offspring, respectively. The serum concentration of IGF-I was decreased (p < 0.05) by 17% and 22% in EF as compared with PF and AF fetuses. Fetal body weight showed positive correlations with fetal serum IGF-I IGF-II (r = 0.566, p < 0.01, and r = 0.412, p < 0.05, respectively) Fetal liver weight correlated with fetal liver IGF-I and IGF-II, with r values of 0.514 (p < 0.01) and 0.493 (p < 0.01). Hepatic IGF-II mRNA abundance was decreased (p < 0.05) by 27% and 26% in EF as compared with PF and AF offspring. The level of fetal liver IGF-I mRNA expression was low but was also reduced comparably in EF pups. IGFBP content in EF fetal serum was increased (p < 0.05 vs AF), and correlated negatively with fetal body weight (r = -0.505, p < 0.01). The diminished IGF-I and IGF-II gene expression and the reduced tissue and circulating peptide levels, along with a converse change in serum IGFBP abundance, may have a role in the pathogenesis of fetal alcohol syndrome.

Differential removal of insulin-like growth factor binding proteins in rat serum by solvent extraction procedures

Solvent extraction of serum and other biological fluids at an acidic pH is a convenient method to remove the insulin-like growth factor binding proteins (IGFBPs); however, an incomplete removal of IGFBPs can occur and this can potentially interfere with the radioimmunoassay of insulin-like growth factors (IGFs). This study compared the removal of IGFBPs from normal adult rat serum and 5-day old neonatal rat serum by acid-gel filtration, and three solvent extraction methods, i.e., acid-ethanol (AE), acid-cryo-ethanol (ACE) and formic acid-acetone (FAA) treatments by western ligand blotting and slot-blotting analysis. In adult rat serum all three extraction methods removed nearly 75% of total IGFBPs present. For the neonatal serum, AE and FAA were very inefficient in eliminating the IGFBPs, while ACE was somewhat better, as it removed nearly 30% of IGFBPs. Ligand blots of extracted samples showed that IGFBPs of lower size range, 24 to 32 kDa (IGFBP-4, IGFBPs-1 and -2), were resistant to solvent extraction. Acid-gel filtration, in contrast, eliminated > 95% of IGF-binding components in both sera. Determination of IGF-I concentrations in samples after gel filtration and extraction methods revealed lower IGF-I values in neonatal serum in acid extracted samples. These data caution against using solvent extractions for IGFBP removal in fetal/neonatal serum.

Effects of ethanol on DNA, RNA, and protein synthesis in rat astrocyte cultures

Brain growth retardation is a major feature of the fetal alcohol syndrome (FAS). Insulin and insulin-like growth factors (IGF-I and IGF-II) exert significant growth-promoting effects on the central nervous system (CNS). The present study examined the effects of ethanol and its interactions with growth factors on the incorporation of labeled precursors into DNA, RNA, and protein in primary astrocyte cultures prepared from term fetal rats. Cultures were exposed to ethanol for 18hr in serum-free medium before measuring nucleoside or amino acid incorporation into acid-precipitable cell constituents. Under basal conditions, ethanol induced dose-dependent changes in the rates of incorporation of tritiated thymidine, uridine, and valine. The fraction of the total thymidine uptake that was incorporated into DNA was reduced in the presence of 100 and 200 mM ethanol. Effects on uridine and valine incorporation paralleled cell uptake. Insulin (10(-6) M) and IGF-I (10(-9) M) increased (p less than 0.01) incorporation of radiolabeled thymidine, uridine, and valine. Analysis of variance indicated highly significant interactions between ethanol and the effects of growth factors on incorporation of both nucleosides and valine. Interference with the action of neurotrophic factors may be a significant factor in fetal brain growth retardation associated with maternal ethanol ingestion.