Model study of the pressure build-up during subcutaneous injection.

Thomsen, Maria; Hernandez-Garcia, Anier; Mathiesen, Joachim; Poulsen, Mette; Sørensen, Dan N; Tarnow, Lise; Feidenhans'l, Robert · PLoS One · 2014

basic_science · Level V

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Abstract

In this study we estimate the subcutaneous tissue counter pressure during drug infusion from a series of injections of insulin in type 2 diabetic patients using a non-invasive method. We construct a model for the pressure evolution in subcutaneous tissue based on mass continuity and the flow laws of a porous medium. For equivalent injection forces we measure the change in the infusion rate between injections in air at atmospheric pressure and in tissue. From a best fit with our model, we then determine the flow permeability as well as the bulk modulus of the tissue, estimated to be of the order 10-11-10-10 m2 and 105 Pa, respectively. The permeability is in good agreement with reported values for adipose porcine tissue. We suggest our model as a general way to estimate the pressure build-up in tissue during subcutaneous injection.

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