Comparison of irrigation solutions and devices in a contaminated musculoskeletal wound survival model

There is much to learn about the effectiveness of different methods currently used for the irrigation of open wounds. The purpose of this study was to compare various approaches in a survival animal model.

We used an established goat model involving the creation of a reproducible complex musculoskeletal wound followed by inoculation with Pseudomonas aeruginosa (lux) bacteria. This genetically altered luminescent bacterium provides the ability for quantitative analysis with a photon-counting camera system. For Study 1, wound irrigation was performed six hours after the injury and inoculation; the goats were assigned to four treatment groups: normal saline solution, bacitracin solution, castile soap, and benzalkonium chloride. All wounds received sharp débridement and irrigation with use of a pulsatile lavage device (19 psi). Images and photon counts were obtained prior to irrigation, after irrigation, and forty-eight hours after injury and inoculation. For Study 2, we used the same animal model and compared bulb syringe and pulsatile lavage irrigation with saline solution.

In Study 1, the irrigation treatment lowered the bacterial counts in all treatment groups. The greatest reduction was seen with castile soap, which lowered the photon count to 13% of the pretreatment level. This was followed by benzalkonium chloride, bacitracin, and saline solution at 18%, 22%, and 29%, respectively. At forty-eight hours, imaging showed a rebound in bacterial counts in every group. The highest rebound was measured in the castile soap group, which rebounded to 120% of the pretreatment level. The benzalkonium chloride group experienced a rebound to 94% of the pretreatment level. These were followed by bacitracin solution (89%) and normal saline solution (68%). In Study 2, both treatment methods were effective in removing 75% of the bacteria initially. At forty-eight hours, the bacterial levels in the pulsed lavage group rebounded to 94% of the original levels (compared with 48% in the bulb syringe group). The difference in the mean photon count ratios at forty-eight hours was significant (p = 0.048).

Approaches used to remove bacteria from wounds, such as irrigants other than saline solution or high-pressure devices, may not have the best clinical outcome.