Comparison of bulb syringe and pulsed lavage irrigation with use of a bioluminescent musculoskeletal wound model.

BACKGROUND: Despite the fact that wound irrigation is a common surgical procedure, there are many variables, including delivery device, irrigant type, and fluid volume, that have yet to be optimized. The purpose of this study was to compare, with use of transgenic bioluminescent bacteria and standard quantitative microbiological methods, the efficacy of pulsed lavage and bulb syringe irrigation in reducing wound bacterial counts. METHODS: A caprine model of a complex, contaminated musculoskeletal wound was developed with use of a bioluminescent strain of Pseudomonas aeruginosa that can be quantified. Luminescent activity was recorded as relative luminescent units with use of a photon-counting camera six hours after the wound was created and inoculated. Twelve goats were randomly assigned to either the pulsed lavage group or the bulb syringe irrigation group. Each wound was irrigated with normal saline solution in 3-L increments for a total of 9 L and was imaged after each 3-L increment. In addition, quantitative culture samples were obtained from different tissues within the wound before and after irrigation. RESULTS: Pulsed lavage decreased the amount of relative luminescent units by 52%, 64%, and 70% at 3, 6, and 9 L, respectively. The bulb syringe irrigation reduced the amount of relative luminescent units by 33%, 44%, and 51% at these same time-points. Significant differences in luminescence were noted between the two groups after both 6 and 9 L of irrigation (p < or = 0.04). The correlation coefficients between relative luminescent units and quantitative cultures for the condition before irrigation and after irrigation were r = 0.96 and 0.83, respectively. CONCLUSIONS: Pulsed lavage was more effective than bulb syringe irrigation in reducing bacterial luminescence after both 6 and 9 L of irrigation. Both device and volume effects can be demonstrated with use of this model. Bioluminescent bacteria provide a method to visualize bacterial distribution and to quantify the bacteria in a wound. CLINICAL RELEVANCE: Pulsed lavage is a more effective and efficient method of irrigation to remove bacteria in a complex musculoskeletal wound. In the model we used, pulsed lavage irrigation with 3 L of saline solution resulted in a reduction of approximately the same amount of bacteria as did irrigation with 9 L with use of a bulb syringe.

The role of epimysium in suturing skeletal muscle lacerations.

BACKGROUND: Direct muscle trauma is a common and disabling clinical problem. Surgical muscle repair is difficult to evaluate because reliable repair techniques have not been established scientifically. The purpose of this study was to assess the biomechanical properties of epimysium, the collagenous tissue sheath that surrounds muscles in the body. STUDY DESIGN: We surgically repaired transected porcine muscle bellies with and without epimysium. For both groups, 25 figure-eight stitches in lacerated quadriceps bellies from a euthanatized pig were loaded under tension on a biomechanical machine (model 8521S, Instron Company). Maximum loads and strains were measured and mechanisms of failure recorded. RESULTS: The mean load for repairs with epimysium (25.1 N) was significantly higher (p = 0.034) than that for repairs without epimysium (21.2 N). The mean strain for repairs with epimysium (10.4%) was significantly higher (p < 0.001) than that for repairs without epimysium (7.3%). The mechanisms of failure were also different. Among epimysium repairs, 15 stitches avulsed muscle transversely, and 10 stitches tore out longitudinally from the muscle. In the nonepimysium group, 1 suture avulsed muscle and 24 sutures tore out. Muscle was the weakest element in each test. CONCLUSIONS: These data showed that epimysium incorporation into suturing improves the capacity of repairs to bear force. These findings fill a knowledge gap and may improve outcomes of muscle suturing. By focusing the experiment on biomechanical properties of muscle stitching, this study showed the key role epimysium plays in muscle suturing.

Evaluation of commercially available fluid-warming devices for use in forward surgical and combat areas.

The fluid-warming capabilities of four individual fluid warmers, i.e., Level 1, FMS 2000, Thermal Angel, and Ranger, were compared to evaluate their potential for medical use in forward military echelons of care. Lactated Ringer's solution (LR) and Hextend at room temperature (20 degrees C) or refrigerated temperature (4-7 degrees C) and packed red blood cells at 4 degrees C to 7 degrees C were used with each warmer at two different flow rates. The FMS 2000 consistently warmed all fluids to approximately 37 degrees C, regardless of the starting temperature or flow rate. The Level 1 and Ranger also efficiently warmed all fluids except cold LR to approximately 37 degrees C. The Thermal Angel generally warmed room temperature fluid, cold Hextend, and packed red blood cells to at least 33 degrees C to 34 degrees C but could not warm cold LR. The clinical standard is to have fluids warmed to 32 degrees C at a minimum and more preferably to 34 degrees C to 35 degrees C. Of the fluid warmers tested, only the Thermal Angel failed to achieve such a temperature in warming cold LR. Data from the present study suggest the Ranger and FMS 2000 to be operationally adaptable to at least echelons 1 and 2, respectively, whereas far-forward use of the Thermal Angel has limitations.

Tobramycin-impregnated calcium sulfate prevents infection in contaminated wounds.

Open fractures often are associated with increased rates of infection and nonunion, multiple surgical procedures, and delayed return to preinjury activity. Antimicrobial bone graft substitutes used as an alternative to antibiotic cement beads and/or delayed autologous bone grafting may provide a useful adjunct in patients with open fractures. A stable, unicortical defect was created and contaminated with 30 microL of 5 x 10 colony-forming units/mL of Staphylococcus aureus in the proximal tibial metaphysis of Spanish goats. The negative control group received no treatment, the carrier group received synthetic bone graft alone, the positive control group received tobramycin antibiotic cement, and the treatment group received tobramycin antimicrobial synthetic bone graft (calcium sulfate). After a 3-week evaluation period, intraosseous microbiologic specimens were obtained. The Staphylococcus aureus contaminant was recovered in 11 of 12 animals (mean = 6.9 x 10 colony-forming units/g marrow) in the negative control group and in all animals (mean = 2.2 x 10 colony-forming units/g marrow) in the carrier group. Bacteria were not found in the antibiotic-treated groups. The tobramycin-impregnated calcium sulfate was effective in preventing infection in a contaminated defect. It could be beneficial in reducing the number of surgeries and recovery time because it is bioabsorbable and osteoconductive.