A study of use of mini-bladders in active compression as a treatment for venous disease and lymphoedema

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Nandasiri, HMAGK, 2019. A study of use of mini-bladders in active compression as a treatment for venous disease and lymphoedema. PhD, Nottingham Trent University.

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Abstract

Venous disease of human lower limbs can cause a range of disorders that have a significant impact on the quality of life of patients. The sheer prevalence of varicose veins and its associated costs of treating late complications, such as chronic ulcers, contribute to a higher burden on health care resources as well as affecting the quality of life of people in the western world. The established gold standard of treatment is the application of graduated compression, applied mostly by medical compression bandages (MCB) and graduated compression stockings (GCS). Both systems are passive treatment methods as the pressure is generated by the component of the tangential force created due to the fabric tension resulted by the fabric stretch, which fails to provide uniform pressure around the leg circumference.

This thesis presents the fundamental research of design, development, and evaluation of an active compression system consisting of an array of silicone based inflatable mini-bladders, which can provide a better solution for the treatment of venous disease and also lymphoedema. The mini-bladders were designed with two elastomeric layers; however, the mini-bladder inflation was limited only to one layer when the mini-bladder was filled with air. The minibladders could apply a radial force on to the treated surface when inflated, and the pressure in mini-bladders could be determined by measuring the back pressure, thus providing the ability to inflate mini-bladders to a predefined pressure. An array of mini-bladder can be used to apply pressure over a large area with a pre-determined resolution in order to create a graduated pressure profile. The 3-D deformation profile of mini-bladders was analysed using Finite Element Modelling and the simulations showed a good agreement with the experimental results within the pressure region which of interest for the compression therapy. The pressure transmission characteristics of the mini-bladders were investigated, initially on hard surfaces and then extended to a biofidelic leg surrogate. The hexagonal shaped mini-bladders provided the best pressure transmission properties. As a higher packing density can be achieved with hexagonal shaped mini-bladders in a honeycomb structure, a prototype active compression device was designed with hexagonal shape mini-bladders. Moreover, the interface pressure generated by the mini-bladders demonstrated a good linear relationship with the mini-bladder inflation pressure, which could be used as a calibration curve for the mini-bladders to inflate the mini-bladders to apply a predefined pressure. The second phase of the experiments, were conducted with a biofidelic lower leg surrogate covered with artificial skin and fat layers of different Young's modulus values. To the best of the author's knowledge this type of validation was the first of its kind in compression therapy research. The research has proved that mini-bladders can be used to apply a uniform circumferential pressure irrespective of the position of the lower leg surrogate; which proves the validity of the research hypothesis. The pressure propagation through the fat layers were around 35%-45% of the mini-bladder inflation pressure. Moreover, the propagation of the pressure through the fat layers varied with the modulus of the fat layers; the fat layer having lowest modulus recorded the highest pressure transmission percentage.

A prototype of an active compression system was designed with mini-bladder arrays integrated within a silicone layer, in which the mini-bladders were directly in-contact with the skin. The laboratory experiments demonstrated that the developed active compression system was capable of delivering the required graduated pressure profiles.

Item Type:	Thesis
Creators:	Nandasiri, H.M.A.G.K.
Date:	July 2019
Rights:	This work is the intellectual property of the author. You may copy up to 5% of this work for private study, or personal, non-commercial research. Any re-use of the information contained within this document should be fully referenced, quoting the author, title, university, degree level and pagination. Queries or requests for any other use, or if a more substantial copy is required, should be directed to the owner(s) of the Intellectual Property Rights.
Divisions:	Schools > School of Art and Design
Record created by:	Linda Sullivan
Date Added:	23 Oct 2019 13:28
Last Modified:	23 Oct 2019 13:28
URI:	https://irep.ntu.ac.uk/id/eprint/38028