Comparison of tissue damage, cleansing and cross-contamination potential during wound cleansing via two methods: lavage and negative pressure wound therapy with instillation

Abstract

The use of lavage was compared to negative pressure wound therapy (NPWT) with instillation (NPWTi) to assess extent of soft tissue damage, debris removal and environmental cross-contamination susceptibility in three distinct models. Scanning electron microscopy in an ex vivo model showed increased visible tissue trauma from lavage treatment at low and high pressures versus NPWTi, with the degree of trauma relative to the pressure of the irrigant. These results were corroborated in granulating full-thickness excisional swine wounds coated with dextran solution to simulate wound debris. Both low-pressure lavage and NPWTi demonstrated effective cleansing in this model, reducing debris by >90%. However, using three-dimensional photography to evaluate tissue damage by measuring immediate tissue swelling (changes in wound volume and depth) showed significantly greater (P < 0.05) swelling in low-pressure lavage-treated wounds compared with NPWTi-treated wounds. Lastly, bench top wound models were inoculated with fluorescent bacterial particles to assess environmental cross-contamination potential and collected at measured distances after treatment with low-pressure lavage and NPWTi. No evidence of cross-contamination was found with NPWTi, whereas one-half of the particles became 'aerosolised' during low-pressure lavage (P < 0.05). Collectively, these studies demonstrate the effective wound cleansing capabilities of NPWTi without the tissue damage and environmental contamination associated with lavage.

Keywords: Environmental cross-contamination; Lavage; NPWTi; Tissue trauma; Wound cleansing.

Figure 1

Process of ex vivo wound model generation. (A) 4.5 cm × 4.5 cm stainless steel block placed underneath the pork loin. (B) Stainless steel template with a 5 cm × 5 cm opening placed over the pork loin and the block underneath it so that this portion rises through the opening. (C) Wound created utilising the wound template.

Figure 2

Experimental setup for environmental cross‐contamination assessment illustrating the placement of concentric microplates to surround the wound at specified distances from the wound edge on a sacral pressure ulcer model. (Note: For purposes of clarity, the figure depicts only one corner of the actual experimental setup.)

Figure 3

Ex vivo wound model punch biopsy samples illustrating blanching after cleansing treatments. Note the visible increase in degree in maceration or blanching as the pressure of the cleansing treatment increases. (A) Negative pressure wound therapy with instillation (NPWTi). (B) Low‐pressure lavage. (C) High‐pressure lavage.

Figure 4

Scanning electron microscope images of ex vivo model wound surfaces after cleansing treatments. Areas of trauma and disruption are indicated by arrows. (A) No treatment at 500× magnification. (B) Negative pressure wound therapy with instillation (NPWTi) at 402× magnification. (C) Low‐pressure lavage at 332× magnification. (D) High‐pressure lavage at 395× magnification.

Figure 5

Observed blanching of the porcine wound bed. (A) Before negative pressure wound therapy with instillation (NPWTi) treatment. (B) Post NPWTi treatment. (C) Before low‐pressure lavage treatment. (D) Post low‐pressure lavage treatment with blanched areas circled.

Figure 6

Fluorescence signal of porcine wound bed images before and after cleansing treatments. (A) Before negative pressure wound therapy with instillation (NPWTi) treatment with the wound circled for clarification. (B) Post NPWTi. (C) Before low‐pressure lavage. (D) Post low‐pressure lavage.

Figure 7

Percentage of debris cleansed on porcine wound bed after cleansing treatments in comparison to before cleansing treatment for negative pressure wound therapy with instillation (NPWTi; P < 0.0001) and low‐pressure lavage (P < 0.0001); n = 12; data shown as mean ± SEM.

Figure 8

Determination of wound swelling via wound volume and wound depth ratio. Ratio = 1 indicates no swelling; ratio > 1 indicates increased swelling; ratio <1 indicates reduced swelling; * significantly different from negative pressure wound therapy with instillation (NPWTi) for wound volume (P = 0.0086) and wound depth (P = 0.0006); n = 12; data shown as mean ± SEM.

Figure 9

Bacterial particles detected after cleansing treatments. * Significantly different from LPL w/Pressurised Can, LPL w/Spray Bottle #1 and LPL w/Spray Bottle #2, within the bacterial strain group (P < 0.05); LPL, low‐pressure lavage; ROCF, reticulated open cell foam; N/A, not applicable n = 3; data shown as means ± SEM.