The fluid dynamics of simultaneous irrigation with negative pressure wound therapy

Abstract

Saline irrigation has been shown to be both experimentally and clinically efficacious in decreasing bacterial contamination as well as decreasing infection rates. The dynamics of irrigation delivery fall into two primary categories: simultaneous and intermittent irrigation. An important component to irrigation therapy is distribution of irrigation solution to hard-to-reach areas of a wound bed, including undermining and fissure-like structures. Here we test the effectiveness of simultaneous irrigation to fill the irregular structures of a wound bed. In order to visualise the dynamic movement of irrigation solution, three-dimensional wound models were constructed using clear synthetic ballistic gel. Wounds with the aforementioned characteristics were carved into the ballistic gel with varying area, depth and volume. All three wounds were dressed as per manufacturer's instructions. Data demonstrate that simultaneous irrigation is effective in reaching all parts of a wound bed in wound models that have both undermining and tunnelling, and irrigation effectively saturates bridged wounds. Finally, this study shows that there is constant turnover of irrigation solution in the wound that is driven more by administration volume and less by flow rate. These data show that simultaneous irrigation is an effective technique for delivering irrigation solution to both simple and complex wounds.

Keywords: NPWT; Simultaneous irrigation; Wound irrigation; Wound model.

Figure 1

Wound model. (A) Wound model carved out of clear ballistic gel filled with blue solution to aid in visualisation. (B) Wound model dressed with white and black polyurethane foam.

Figure 2

Dynamics of irrigation solution delivered simultaneously with negative pressure wound therapy (NPWT). Still shots were taken at noted time points from video of simultaneous irrigation. (A) At 0 second NPWT has been applied. (B) Irrigation solution begins to enter the wound model (10 seconds). (C) Irrigation solution moves across the wound (15 seconds). (D) Irrigation solution exits the wound model through the tube connected to the NPWT device (25 seconds). (E) Visualisation of the base of the wound model demonstrates complete saturation of the dressing (25 seconds).

Figure 3

Irrigation solution reaches complex wound structures when delivered simultaneously with negative pressure wound therapy (NPWT). (A) Wound models with tunnel and undermined structures are efficiently exposed to simultaneous irrigation. (B) Visualisation of model from below. (C) Two independent wound models bridged with polyurethane foam. (D) Irrigation solution reaches both wound structures when applied simultaneously with NPWT. (E) Visualisation of wound model from below.

Figure 4

Irrigation delivered simultaneously with negative pressure wound therapy (NPWT) capably displaces solution contained in a wound. (A) NPWT is applied to wound model, and clear irrigation solution is delivered to fill the wound. (B and C) Clear irrigation solution is switched to blue irrigation solution, which begins to infiltrate the wound model displacing the clear solution. (D) Blue irrigation solution exits the tube towards the collection canister after the entire volume from the wound model has been displaced. (E) View from the bottom of the model demonstrating complete displacement of the clear solution by the blue solution.