A Confined Compression Technique for Hydraulic Conductivity Measurement in Soft Tissues

Multiphasic tissue models have been used extensively to predict the behavior of cartilaginous tissues [1]. Their application to other soft tissues, however, has often been overlooked. Unlike the more commonly used continuum model of the viscoelastic solid [2], multiphasic models allow us to infer the behaviors and properties of tissue subcomponents by observing the behavior of the tissue whole. As a great deal of tissue function and structure is related to the control and transport of fluids and fluid-borne agents, there is clearly a need for this insight in all tissues. For example, there has been a great deal of interest recently in the possibility of modifying the flow properties of solid tumors and other tissues to allow the targeted delivery of large molecular weight drugs, such as chemotherapeutic or genetic agents [3–4]. It is well known that the high interstitial fluid pressures, confused vasculature, and lack of a lymphatic system prevent the effective distribution of directly injected or systemically administered drugs into tumors [3]. Increasing the effective permeability of these tumors can ameliorate these issues and allow for more effective treatment. A handful of studies have found that the biphasic model, along with some basic experimental tools, can reasonably represent the flow properties of tumors [4–5]. In this paper, we describe a technique using a simple confined compression experiment with the biphasic model to measure the hydraulic conductivity of samples of cardiac tissue.