How influential is the stiffness of the foam dressing on soft tissue loads in negative pressure wound therapy?

Negative pressure wound therapy (NPWT) is an established adjunctive modality for treatment of both acute and chronic wounds. However, little is known about the optimal settings and combination of treatment parameters and importantly, how these translate to target tissue strains and stresses that would result the fastest healing and buildup of good-quality tissues. Here we have used a three-dimensional open wound computational (finite element) model that contains viscoelastic skin, adipose and skeletal muscle tissue components for determining the states of tissue strains and stresses in and around the wound when subjected to NPWT with foam dressings of varying stiffnesses. We found that the skin strain state is considerably more sensitive to the pressure level than to the stiffness of the foam dressing within a 8.25 to 99 kPa range which covers the current industry standard. Accordingly, peri-wound skin strains and stresses which stimulate cell proliferation/migration and angiogenesis and thereby, healing of the wound, can be more effectively controlled by adjusting the pressure level than by varying the stiffness of the foam dressing.