Fri., 10/19/07 Basic Science, Paper #44, 4:54 pm OTA-2007
Comparison of Negative-Pressure Dressing and Standard Dressing in a Contaminated Open Fracture Model
MAJ Steven J. Lalliss, MD (n); CPT Joanna G. Branstetter, MD (n); Joseph C. Wenke, PhD (n);
US Army Institute of Surgical Research, Fort Sam Houston, Texas, USA
Purpose: The purpose of this study is to determine if wounds that receive negative-pressure wound therapy (NPWT) will have fewer bacteria than wounds that receive wet-to-dry dressing in a contaminated open fracture wound model.
Methods: Complex orthopaedic wounds were created on the proximal left leg of 16 anesthetized goats. A 35-cm2 patch of skin and a portion of the anterior compartment muscles were removed; the remaining muscle was freeze-injured. A unicortical 10-mm-diameter defect was created in the proximal tibial metaphysis. The wounds were inoculated with a strain of Pseudomonas aeruginosa (lux), genetically modified to emit photons, thereby allowing quantification of bacterial concentration with a photon-counting camera system. The wounds were débrided and irrigated with 9 L of saline 6 hours after inoculation, and the animals were assigned to one of two groups. The first group received wet-to-dry dressing changes twice a day; the second group received a NPWT (VAC) with dressing changes every 48 hours. Both groups received repeat débridements every 48 hours for 6 days. Imaging was performed both immediately prior to and after débridements, and luminescent activity was recorded as relative luminescent units. Samples of muscle within the wound and from the contralateral limb were taken to calculate the edema index (ratio of muscle wet-to-dry weight of experimental vs contralateral).
Results: There were significantly fewer bacteria (P <0.02) at all imaging sessions after the initial débridement and irrigation. At the 144-hour time point, the wounds in the NPWT and wet-to-dry groups contained 74 ± 64% and 464 ± 289% of the baseline amount, respectively (P = 0.0041). Edema was significantly higher in the muscle of the goats in the wet-to-dry group compared to the NWPT group with an edema index of 1.81 ± 0.18 and 1.47 ± 0.16, respectively (P = 0.0035).
Conclusions and Significance: NPWT has demonstrated an increase in healing capacity of both acute and chronic wounds. The reduction of bacterial contamination in the wound that was demonstrated in this study supports the use of this device in the treatment of contaminated open fractures. We hypothesize that this reduction in bacteria is a result of decreased edema, which allows more blood flow and helps create an environment conducive to healing and infection clearance.
If noted, the author indicates something of value received. The codes are identified as a-research or institutional support; b-miscellaneous funding; c-royalties; d-stock options; e-consultant or employee; n-no conflicts disclosed, and *disclosure not available at time of printing.
• The FDA has not cleared this drug and/or medical device for the use described in this presentation (i.e., the drug or medical device is being discussed for an “off label” use). ◆FDA information not available at time of printing.