Effectiveness of fluid introduction and distribution as a wound-cleansing option: Comparison of continuous irrigation and periodic instillation with negative pressure wound therapy

A widely accepted and effective treatment for various wound types is negative pressure wound therapy (NPWT). The utilization of NPWT in conjunction with instillation has recently gained momentum in the healthcare arena with implementation of either continuous instillation, whereby solution is added to the wound bed simultaneous to the imparting of negative pressure [1-2], or periodic instillation (NPWTi), which consists of a cycle of instillation with a soak time followed by NPWT [3-4]. With the effective cleansing of the wound being a key step in the wound healing continuum, the combination of negative pressure and instillation is anticipated to be more readily incorporated into common practice, with nurses being at the forefront.  To evaluate the effectiveness of fluid introduction and distribution into wound beds using these cleansing methods that incorporate negative pressure, agar-based models and colored instillation solutions were created to visualize exposure via agar staining. Previously, this technique illustrated that periodic instillation achieved more uniform exposure of fluid throughout the wound, even in undermined and tunneled regions in an upward facing wound model [5]. Here, other wound orientations utilizing these two instillation techniques are investigated. In the inverted position, the continuous instillation method demonstrated exposure of the instillation fluid solely to the edges of the wound closest to the peri-wound and an inability to reach the deeper recesses of the wound. In contrast, periodic instillation allowed for complete wound surface coverage. In a 90^oorientation, periodic instillation demonstrated complete instillant wound coverage, whereas exposure was limited to the bottom edge using the continuous irrigation technique. Thus, this study illustrates that gravity impacts fluid distribution in continuous instillation; however, harnessing periodic instillation therapy overcomes the influence of gravity, thereby completely filling the wound and allowing exposure of all wound areas, even undermining and tunneling.