Dynamic computational simulations for evaluating tissue loads applied by regulated negative pressure-assisted wound therapy (RNPT) system for treating large wounds

Regulated negative pressure-assisted wound therapy (RNPT) is one of the most important wound treatment technologies developed and applied over the last two decades. To-date RNPT has been proven to be clinically effective in treating chronic wounds, however, the effects of different specific pressure delivery protocols on the progress and quality of tissue repair are not adequately understood yet. Here, we suggest a viscoelastic, three-dimensional finite element modeling framework of RNPT, with several realistic features such as a non-symmetrically configured multi-layered tissue structure. The effects of the RNPT system on the wound-bed were simulated by applying time varying pressure boundary conditions. Three commonly-used operation modes were simulated: continuous, non-continuous intermittent and dynamic, and each mode was applied at four different pressure levels. Outcome measures of strain and stress magnitudes and distributions were acquired from the dermis and subcutaneous fat. Taken together, the strain and stress data from the different simulated RNPT modes and intensities demonstrated that tissue loads which are actually applied in and around the wound, and at the different tissue components of the wound, can differ substantially from the pressure levels that are set in the device during therapy sessions. This is critical information for understanding the potential effects of RNPT, for setting the device prior to therapy and for designing the next generation of these systems.