Experimental Investigation of Pressure Applied on the Lower Leg by Elastic Compression Bandage

Comparing the Energy-Stretch Properties of Two Compression Bandage Systems in a Laboratory-Based Test under Controlled Conditions

OBJECTIVE

To compare the characteristics of two commercially available compression systems, a dual-compression bandage system (DCS) and a traditional two-layer bandage (TLB), using a laboratory bench test.

METHODS

The compression systems were evaluated in a computer-controlled tensile test to generate force-deflection curves for each sample. The compressive work and the theoretical pressure applied to the limb by the respective compression bandages were calculated at the maximum stretch and a stretch instructed by the manufacturers. The manufacturer of the DCS provides reference points on how much the bandage should be stretched to provide the desired pressure, and the TLB stretch was calculated from the product’s datasheet.

RESULTS

The combined results of layers 1 and 2 for the DCS showed greater load and work than the TLB at both the maximum and recommended stretch. The recommended stretch for DCS and TLB was less than 50% of the deflection up to the breaking point.

CONCLUSIONS

The high work provided by the two layers of the DCS suggests a wider range of performance than the TLB when applied to the lower limb, especially after the limb volume is initially reduced by compression. Moreover, using the tensile test and the guide of the reference points on layers 1 and 2 from DCS, the calculated pressure achieved the expected values stated by the manufacturer. Human studies should be conducted to determine whether the reference points provided by DCS are beneficial for obtaining repeatable values.

Inability of Laplace's law to estimate sub-bandage pressures after applying a compressive bandage: a clinical study

OBJECTIVE

The aim of the current study was to compare pressures exerted on the lower limb by a high compression bandage as recorded by sub-bandage sensors and those estimated by Laplace's law. The correlation between pressures obtained in each anatomical zone and the corresponding limb perimeters were explored.

METHOD

For the measurement of sub-bandage pressures, four anatomical zones in the lower right limb were determined. Pressures were recorded by nine pneumatic sensors and a PicoPress transducer. A two-layer compression bandage system (UrgoK2, Urgo Group, France) was used for the dressing. Pressures were registered in supine position. Sensor pressures were compared with those estimated by a modified Laplace's equation.

RESULTS

A total of 47 female volunteers were recruited (mean age: 21.9±2.3 years) to the study. In the four anatomical segments studied, pressures obtained by the sensors were lower than would be expected by applying Laplace's law (p<0.05). The biggest difference between the two methods was found at the supramalleolar level (42.1% lower by sensors compared with Laplace's equation). The correlation coefficient between pressure recorded by the sensors and that calculated at the perimeters was very weak, ranging from 0.5233 to 0.9634.

CONCLUSION

Laplace's law, used to predict the sub-bandage pressure after applying a compressive bandage in the lower limb, was not useful, providing significantly higher pressures than those obtained by pneumatic sensors. Laplace's law underestimates the variable musculoskeletal components at the different segments of lower limb that act as compression damping forces.

In-silico pre-clinical trials are made possible by a new simple and comprehensive lumbar belt mechanical model based on the Law of Laplace including support deformation and adhesion effects

Lower back pain is a major public health problem. Despite claims that lumbar belts change spinal posture due to applied pressure on the trunk, no mechanical model has yet been published to prove this treatment. This paper describes a first model for belt design, based on the one hand on the mechanical properties of the fabrics and the belt geometry, and on the other hand on the trunk geometrical and mechanical description. The model provides the estimation of the pressure applied to the trunk, and a unique indicator of the belt mechanical efficiency is proposed: pressure is integrated into a bending moment characterizing the belt delordosing action on the spine. A first in-silico clinical study of belt efficiency for 15 patients with 2 different belts was conducted. Results are very dependent on the body shape: in the case of high BMI patients, the belt effect is significantly decreased, and can be even inverted, increasing the lordosis. The belt stiffness proportionally increases the pressure applied to the trunk, but the influence of the design itself on the bending moment is clearly outlined. Moreover, the belt/trunk interaction, modeled as sticking contact and the specific way patients lock their belts, dramatically modifies the belt action. Finally, even if further developments and tests are still necessary, the model presented in this paper seems suitable for in-silico pre-clinical trials on real body shapes at a design stage.

Biotechnologies toward Mitigating, Curing, and Ultimately Preventing Edema through Compression Therapy

For a century-old problem, edema and its treatment have gone remarkably unnoticed by the biomedical community. Given the prevalence of lymphedema and its debilitating repercussions, there is an acute need for both efficacy-based measures and clinical standards to guide compression garment design and therapeutic application. This review outlines the current state of the art in compression treatment and suggests an integrated biomedical engineering approach going forward. Characterizing the pressure gradient profiles of commercial compression sleeves is necessary to better understand the role of compression treatment in the mitigation of swelling. Integration of pressure sensor technologies with advanced materials design and manufacture provides a critical path not only to elucidate the mechanisms of but also to improve on current compression-based therapies and associated therapeutic devices.

Customizing elastic pressure bandages for reuse to a predetermined, sub-bandage pressure: A randomized controlled trial

Objective

A randomized clinical trial was performed to compare the effectiveness of unmarked bandages and customized bandages with visual markers in reproducing the desired sub-bandage pressure during self-bandaging by patients.

Method

Ninety patients were randomly allocated to two groups (“customized bandages” and “unmarked bandages”) and asked to perform self-bandaging three times. The achievement of a pressure between 35 and 45 mmHg in at least two of the three attempts was defined as adequate quality.

Results

Adequate quality was achieved by 33.0% when applying the unmarked bandages, and 60.0% when applying the customized bandages ( p = 0.02). Use of the customized bandage and previous experience of bandaging were independent predictors for the achievement of the predetermined sub-bandage pressure ( p = 0.005 and p = 0.021, respectively).

Conclusion

Customized bandages may achieve predetermined sub-bandage pressures more closely than standard, unmarked, compression bandages.

Clinical trials registration

ClinicalTrials.gov (NCT02729688). Effectiveness of a Pressure Indicator Guided and a Conventional Bandaging in Treatment of Venous Leg Ulcer. https://clinicaltrials.gov/ct2/show/NCT02729688

Use of customised pressure-guided elastic bandages to improve efficacy of compression bandaging for venous ulcers

Compression bandaging is a major treatment of chronic venous ulcers. Its efficacy depends on the applied pressure, which is dependent on the skill of the individual applying the bandage. To improve the quality of bandaging by reducing the variability in compression bandage interface pressures, we changed elastic bandages into a customised version by marking them with circular ink stamps, applied when the stretch achieves an interface pressure between 35 and 45 mmHg. Repeated applications by 20 residents of the customised bandage and non-marked bandage to one smaller and one larger leg were evaluated by measuring the sub-bandage pressure. The results demonstrated that the target pressure range is more often attained with the customised bandage compared with the non-marked bandage. The customised bandage improved the efficacy of compression bandaging for venous ulcers, with optimal sub-bandage pressure.

Compression therapy for venous disease

For centuries, compression therapy has been utilized to treat venous disease. To date it remains the mainstay of therapy, particularly in more severe forms such as venous ulceration. In addition to mechanisms of benefit, we discuss the evidence behind compression therapy, particularly hosiery, in various forms of venous disease of the lower extremities. We review compression data for stand-alone therapy, post-intervention, as DVT prevention, post-thrombotic syndrome and venous ulcer disease. We also review the data comparing compression modalities as well as the use of compression in mixed arteriovenous disease.

Haemodynamic Performance of Low Strength Below Knee Graduated Elastic Compression Stockings in Health, Venous Disease, and Lymphoedema

OBJECTIVE

To test the in vivo haemodynamic performance of graduated elastic compression (GEC) stockings using air-plethysmography (APG) in healthy volunteers (controls) and patients with varicose veins (VVs), post-thrombotic syndrome (PTS), or lymphoedema. Responsiveness data were used to determine which group benefited the most from GEC.

METHODS

There were 12 patients per group compared using no compression, knee-length Class 1 (18-21 mmHg) compression, and Class 2 (23-32 mmHg) compression. Stocking/leg interface pressures (mmHg) were measured supine in two places using an air-sensor transducer. Stocking performance parameters, investigated before and after GEC, included the standard APG tests (working venous volume [wVV], venous filling index [VFI], venous drainage index [VDI], ejection fraction [EF]) and the occlusion plethysmography tests (incremental pressure causing the maximal increase in calf volume [IPMIV], outflow fraction [OF]). Results were expressed as median and interquartile range.

RESULTS

Significant graduated compression was achieved in all four groups with higher interface pressures at the ankle. Only the VVs patients had a significant reduction in their wVV (without: 133 [109-146] vs. class1: 93 [74-113] mL) and the VFI (without: 4.6 [3-7.1] vs. class1: 3.1 [1.9-5] mL/s), both at p <.05. The IPMIV improved significantly in all groups except in the PTS group (p <.05). The OF improved only in the controls (without: 43 [38-51] vs. class1: 50 [48-53] %) and the VVs patients (without: 47 [39-58] vs. class1: 56 [50-64] %), both at p <.05. There were no significant differences in the VDI or the EF with GEC. Compression dose-response relationships were not observed.

CONCLUSION

Patients with varicose veins improved the most, whereas those with PTS improved the least. Performance seemed to depend more on disease pathophysiology than compression strength. However, the lack of responsiveness to compression strength may be related to the low external pressures used. Stocking performance tests may have value in selecting those patients who benefit most from compression.