Computational investigation of the Laplace law in compression therapy

Comparison of the Effectiveness of Liposuction for Lower Limb versus Upper Limb Lymphedema

OBJECTIVE

Liposuction is the most frequently performed debulking procedure in patients with lymphedema. However, it remains uncertain whether liposuction is equally effective for upper extremity lymphedema (UEL) and lower extremity lymphedema (LEL). In this study, we retrospectively compared the effectiveness of liposuction according to whether it was performed for LEL or UEL, and identified factors associated with outcomes.

MATERIALS AND METHODS

All patients had been treated at least once by lymphovenous anastomosis or vascularized lymphatic transplant before liposuction but without sufficient volume reduction. The patients were divided into an LEL group and a UEL group, and then subdivided further according to whether they completed their planned compression therapy into an LEL compliance group, an LEL non-compliance group, a UEL compliance group, and a UEL non-compliance group. The reduction rates in LEL (REL) and in UEL (REU) were compared between the groups.

RESULTS

In total, 28 patients with unilateral lymphedema were enrolled (LEL compliance group, n = 12; LEL non-compliance group, n = 6; UEL compliance group, n = 10; UEL non-compliance group, n = 0). The non-compliance rate was significantly higher in the LEL group than in the UEL group (p = 0.04). REU was significantly higher than REL (100.1 ± 37.3% vs. 59.3 ± 49.4%; p = 0.03); however, there was no significant difference between REL in the LEL compliance group (86 ± 31%) and REU in the UEL group (101 ± 37%) (p = 0.32).

CONCLUSION

Liposuction seems to be more effective in UEL than in LEL, probably because the compression therapy required for management after liposuction is easier to implement for UEL. The lower pressure and smaller coverage area required for postoperative management after liposuction in the upper limb may explain why liposuction is more effective in UEL than in LEL.

Simulation-based reasoning of residual tissue deformations in a two-chamber test of a lymphedematous leg

A two-chamber inflation-deflation test was recently proposed as a diagnostic method to determine parameters of the intermittent pneumatic compression used as an effective therapeutic modality for lymphedematous limbs. It is crucial that the recorded trends for residual tissue deformations are understood in terms of specific properties of subcutaneous tissue and skin to support diagnostic process. This paper presents a mechanical model of lymphedematous legs in two-chamber tests. The cylindrical geometry composed of layers of skin, modeled as hyperelastic medium, and subcutaneous tissue, modeled as fluid saturated hyperporoelastic medium, is assumed. The results of finite element simulations show the possibility of such combinations of the properties of skin (rigidity) and subcutaneous tissue (rigidity and permeability), which ensures that the model predictions resemble the evolution of tissue residual deformations observed in the two-chamber test. The stiffness and permeability appeared to be the most crucial tissue property determining trend lines of residual deformations. The analysis of the components of displacement of solid matrix and pore fluid pressure explains the mechanisms that are responsible for particular tissue behavior. The moderate role of skin and limitations related to the mechanical and geometrical model assumptions are indicated. Recommendations for treating lymphedema using intermittent compression therapy in relation to the results of the two-chamber test and properties of tissues are discussed.

Effect of Postoperative Compression Therapy on the Success of Liposuction in Patients with Advanced Lower Limb Lymphedema

Objective: There is limited information on postoperative care after liposuction for lymphedema limb. The aim of this retrospective study was to identify the threshold compression pressure and other factors that lead liposuction for lower limb lymphedema to success. Materials and Methods: Patients were divided according to whether they underwent compression therapy with both stockings and bandaging (SB group), stockings alone (S group), or bandaging alone (B group) for 6 months after liposuction. The postoperative compression pressure and rate of improvement were compared according to the postoperative compression method. We also investigated whether it was possible to decrease the compression pressure after 6 months. Liposuction was considered successful if improvement rate was >15. Results: Mean compression pressure was significantly lower in the S group than in the SB group or B group. The liposuction success rate was significantly higher in the SB group than in the B group or S group. There was not a significant difference between the values at 6 months after liposuction and at 6 months after a decrease in compression pressure in the successful group. Conclusion: Our results suggest that stable high-pressure postoperative compression therapy is key to the success of liposuction for lower limb lymphedema and is best achieved by using both stockings and bandages. The postoperative compression pressure required for liposuction to be successful was >40 mmHg on the lower leg and >20 mmHg on the thigh. These pressures could be decreased after 6 months.

The accuracy and precision of interface pressure measuring devices: A systematic review

INTRODUCTION

Interface pressure measuring devices are used to assess the pressures exerted by compression. Their performance, however, has not been considered as a contributing factor to reported inconsistences in the application of compression. A systematic review was undertaken to investigate the performance of commercially available devices used to measure interface pressure.

METHODS

Six databases were searched identifying 17 devices, grouped into five sensor categories.

RESULTS

A range of methodologies assessed the devices' accuracy and precision, including method of pressure application, device calibration and type of surface used. No sensor category outperformed the others, however some individual sensors showed higher accuracy and/or precision compared to others. Two major factors influenced the performance of a number of sensors: the amount of applied pressure and the calibration method used.

CONCLUSION

Inconsistences in the application of compression may reflect, in part, issues related to accuracy and precision of the devices used to assess compression.

Compression Pressure Variability in Upper Limb Multilayer Bandaging Applied by Lymphedema Therapists

Background: Multilayer bandaging (MLB) is often used for lymphedema treatment. Even experienced lymphedema therapists have difficulty applying bandages correctly. The aim of this study was to demonstrate upper limb MLB pressure variability applied by lymphedema therapists. Methods and Results: Twenty-four lymphedema therapists were asked to apply MLB to the healthy volunteer's upper limb. The participants consisted of 20 females and 4 males with a mean age of 43.4 (range: 24-62) years. They included licensed massage therapists, nurses, a judo therapist, an occupational therapist, and a medical doctor. Twenty therapists (83.3%) had clinical experience applying MLB. Compression pressure was measured with PicoPress at 5 cm proximal to the wrist, immediately after the application (phase 1) and after exercise (phase 2). The mean MLB pressure was 67.7 ± 5.0 mmHg in phase 1 and 55.3 ± 4.1 mmHg in phase 2, which were significantly different (p = 1.2 × 10^-10). There was a weak negative correlation between how long the therapist had been practicing MLB and MLB pressure (R = 0.29). Seventeen participants (70.8%) expressed that they had a target pressure in mind when performing MLB. Among the 17 participants, there was no correlation between the target and actual pressures (R = -0.055). Only three participants (17.6%) had an actual MLB pressure within 5 mmHg of their target. Conclusions: The mean MLB pressure was 55.3 ± 4.1 mmHg, which was thought to be too high for the upper limb. Education about applying appropriate MLB pressures to the limbs is necessary.