16.0: Thursday, March 17, 2005

Influence of Lavage Volume on Wound Bacterial Reduction

Mark S. Barlow, MD, John P. Heggers, Lisa J. Gould, and Linda G. Phillips.

Irrigation has long been a cornerstone of effective wound care. To date, the importance of lavage volume has not been quantified. Standardized, infected wounds were created on the dorsa of Sprague-Dawley rats by inoculating them with an well-characterized strain of Staphylococcus aureus. The following day, quantitative cultures were taken before and after lavaging the wounds with normal saline. All lavage was performed manually using a syringe and an 18 gauge catheter. Six study groups were randomly assigned with different lavage volumes. These volumes were based on wound surface area and included 1, 3, 10, 20, 40 and 80 milliliters per square centimeter. Data were analyzed by comparing the difference between the logarithm of colony-forming units (log CFUs) before and after lavage, i.e. the log decrement; the null hypothesis was tested using Student's t-test. A sigmoidal relationship between lavage volume and log decrement in colony counts was found. At lower lavage volumes, no decrement was appreciated. A plateau in the curve was found with a log decrement of 1.2 for lavage volume to surface area ratios of 40:1 and greater (p = 0.004 at 80:1). These data demonstrate that lavage alone can reduce bacterial counts in contaminated wounds by over 15-fold.