| Author: | Piao, Jinli |
| Title: | Reduction of lower limb oedema by gradient compression stockings with physical movements : mechanism, modelling, and evaluation |
| Advisors: | Tao, Xiaoming (SFT) |
| Degree: | Ph.D. |
| Year: | 2025 |
| Subject: | Edema Leg -- Diseases Exercise Hong Kong Polytechnic University -- Dissertations |
| Department: | School of Fashion and Textiles |
| Pages: | xxxi, 187 pages : color illustrations |
| Language: | English |
| Abstract: | Lower limb oedema is common, especially among imbalanced diet and nutrition, prolonged walking, standing, and sedentariness, pregnancy, obese individuals, venous insufficiency, and lymphatic obstruction can also be associated with the oedema generation. Without proper treatment, it can develop into chronic venous disease. Treatment options include medication, leg elevation, compression therapy, manual lymphatic massage, electrical stimulation, and surgery, depending on the symptoms. Because of the side effects of medication, risks of surgery, and inconvenience of other treatments, compression therapy has become a promising long-term solution. Skeletal muscle movement also helps improve blood circulation and reduce oedema. Recent studies have shown that applying compression to the lower limbs can effectively reduce oedema. However, there are still some limitations in current research. Many numerical models only consider limb deformation under pressure and ignore the fluid exchange among blood vessels, tissues, and lymph. They also often overlook the physiological factors of blood and interstitial fluid. Moreover, there are not enough practical trials combining compression methods with physical movements in the treatment of lower limb oedema. To address these challenges, this thesis focuses on the reduction of lower limb oedema through the integration of gradient compression stockings with physical movements. At first, a new simplified capillary-blood-tissue model is proposed based on the computational fluid dynamics (CFD) method to analyse fluid exchange between blood and interstitial fluid and determine critical pressures. Then, various physiological parameters, including capillary and tissue porosity, blood viscosity, and inlet velocity, are studied to investigate their effects on compression treatment for oedema reduction. Lastly, three-phase trial tests are designed and conducted to validate the numerical results and statistically evaluate the efficacy of the compression methods. Furthermore, considering that skeletal muscle movement can enhance blood circulation and contribute to oedema mitigation, specifically dedicated designed lower limb movements (LLMs) are incorporated into these trial tests to accelerate the oedema reduction process. In the numerical study chapter, we developed a two-dimensional numerical model of the capillary-blood-tissue system using the porous media model. This simplified model improves upon previous models by more effectively simulating fluid exchange between blood and interstitial fluid, thus offering a more accurate representation of oedema generation and reduction. In the simulation, a filtration indicator (equal to 90% reabsorption and 10% lymphatic flow) is utilized to evaluate the reduction of oedema. It suggests that oedema reduction is expected if reabsorption exceeds 90%. Conversely, if reabsorption is less than 90%, oedema may persist. Correspondingly, when reabsorption is at 90%, the pressure differential between the blood vessel and the applied pressure is referred to as the "critical pressure". And then, these critical pressures were determined under varying physiological parameters, including capillary and tissue porosity, blood viscosity, and inlet velocity. Our results demonstrated that oedema reduction is directly proportional to the applied constant compression pressure. Additionally, capillary and tissue porosity, along with inlet velocity, significantly influence oedema reduction under constant compression pressure, whereas blood viscosity has a minor effect. Furthermore, constant and harmonic pressures produce similar effects on the percentage of venous outflow at the same pressure amplitude, and harmonic frequency shows no significant sensitivity to the percentage of venous outflow. To validate the numerical results, the three-phase trial tests were conducted to evaluate the efficacy of lower limb oedema reduction. The design of these trial tests integrated gradient compression stockings with LLMs in each phase, aiming to facilitate subsequent trial tests by identifying the most effective approaches: Phase 1: This trial involved young healthy subjects and examined the effectiveness of Class I level gradient medical compression stockings (MCS), non-stretchable WRAP, and bare leg, with and without LLMs. The evaluation was based on volume and circumference measurements. Phase 2: In this phase, elderly subjects with mild oedema were tested to evaluate the efficacy of oedema reduction using Class I level gradient WRAP and MCS, with and without LLMs. The evaluation focused on circumference measurements. Phase 3: The final phase involved a larger group of elderly subjects with mild oedema to evaluate the efficacy and compliance of low-pressure gradient MCS with and without LLMs. This phase also assessed the acceptance of the designed LLMs among the elderly subjects. The study statistically analysed the impact of various wearing conditions, the effect of incorporating LLMs, differences between legs, gender, BMI, and the relationship between dynamic compression pressure during LLMs and the reduction rate in lower limb circumference. The trial tests results demonstrated that regards to young healthy subjects, WRAP (Mean: -66.3 cm3 SD: 51.0 cm3) was bigger than MCS (Mean: -58.5 cm3 SD: 42.0 cm3) and bare leg (Mean: -63.5 cm3 SD: 50.5 cm3) in lower limb volume reduction within the group conducting LLMs, while MCS (Mean: -51.2 cm3 SD: 46.8 cm3) had more volume reduction than WRAP (Mean: -41.9 cm3 SD: 35.6cm3) and bare leg (Mean: -42.4 cm3 SD: 57.6 cm3) in the group without LLMs, as evaluated through water displacement volumetry. There were no significant statistical differences observed among wearing conditions within each group. However, significant circumference reductions were observed in young healthy subjects who conducted LLMs, and applying compression was more effective than bare leg for oedema reduction. MCS with LLMs (Mean: -1.3% SD: 0.8%) had more circumference reduction than WRAP with LLMs (Mean: -0.9% SD: 0.7%) at point C, the WRAP with LLMs (Mean: -1.1% SD: 0.7%) was more effective than bare leg with LLMs (Mean: -0.6% SD: 0.6%) at point D. Furthermore, males showed an extremely significant circumference reduction compared to females when applying MCS at point C, either with or without conducting LLMs (p <0.001). Regarding elderly subjects with mild oedema, MCS was better than WRAP in oedema reduction when applying compression alone, and the integration of MCS and LLMs consistently achieved oedema reduction compared to utilizing MCS alone. In addition, MCS with 2 sets of LLMs significantly had circumference reduction at various lower limb points. Subjects with a BMI ≤ 24.9 performed a more significant circumference reduction rate at certain points than those with a BMI >24.9, regardless of whether LLMs were conducted (p <0.05). The dynamic mean pressure declined and fluctuated during LLMs. The young healthy group showed dynamic mean pressures of 13.3 mmHg in WRAP and 10.5 mmHg in MCS at point C. The elderly group revealed dynamic mean pressures of 5.1 mmHg (=679.9 Pa) in WRAP and 6.5 mmHg (=866.6 Pa) in MCS at point C. These dynamic mean pressures containing compression stockings and muscles' contraction were higher than the critical pressure threshold of 550 Pa with normal physiological parameters in the numerical simulation. Furthermore, more than half of young subjects preferred WRAP due to its convenience in wearing. However, integrating the LLMs with low-pressure MCS performed a more stable quality of life (QoL) score than without LLMs and it was better received in terms of exercise intensity preference among the elderly population. In summary, this thesis comprehensively studied integrating low-pressure compression stockings with physical movements on oedema reduction through numerical simulation and practical trials and provides valuable insights into its potential application in promoting active health. |
| Rights: | All rights reserved |
| Access: | open access |
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