All patients admitted to the Richard M. Fairbanks Burn Center at Eskenazi Health, Indianapolis, IN, were pre-screened for study participation. Patients with a partial-thickness to deep partial-thickness burn of 4%-25% total body surface area (TBSA) requiring surgical debridement and skin grafting were asked to consider participating in the study. Inclusion criteria were that patients be 18-85 years of age and have a 4%-25% TBSA acute partial-thickness to deep partial-thickness injury requiring skin grafting that could be divided into 2 separate 320 cm2 treatment areas. Patients were excluded from participation if a microbiologically proven pre-existing local or systemic bacterial infection was present; antibiotics were administered for more than 48 hours prior to grafting; the patient was taking medications known to have an effect on wound healing or skin pigmentation; presence of a pre-existing condition that may interfere with wound healing (eg, malignancy, diabetes, or autoimmune disease); or a known hypersensitivity to trypsin or compound sodium lactate (CSL) solution existed. Patients who met all inclusion and exclusion criteria were enrolled into the study. Patients were informed about the potential risks and benefits of the procedure and signed consent was obtained from each of them.
All patients underwent general anesthesia for a synchronous wound debridement and skin grafting procedure. Two treatment sites were designated as site A and site B and were then randomized to either treatment with spray keratinocytes procured with the ACH device or MSTSG. All wounds were tangentially excised to healthy dermis with brisk punctate bleeding. Hemostasis was obtained using thrombin spray, epinephrine-soaked laparotomy pads, and electrocautery.
The ACH donor site was a noninjured area, and a dermatome depth setting of 0.006 mm-0.008 mm was used. A 2 cm x 2 cm sample was trimmed from the harvested split-thickness graft. Following the required initial set-up of the ACH unit, the biopsy was placed into the trypsin solution to allow for separation of the dermis and epidermis (Figure 2). The sample was removed after 15 minutes for a test separation of the dermis and epidermis. If the sample did not readily separate it was placed back into the trypsin for an additional 5-10 minutes. Once the dermis and epidermis began to easily separate, the sample was rinsed in the CSL solution and separation was completed providing access to the dermal-epidermal junction. A total of 5 ml of CSL solution was used to intermittently irrigate the device’s work surface while the dermal-epidermal junction of the sample was teased with a scalpel to form a plume of cells that was then aspirated into a 5 ml syringe to form a single suspension. Following a filtering process, the suspension was aspirated into a new 5 ml syringe, the spray nozzle was attached to the syringe, and the suspension was delivered to the field for application (Figure 3).
The remainder of the skin was harvested from a separate noninjured area with a dermatome setting of 0.010-0.012 and meshed 2:1 to cover the control site. The MSTSG was secured with staples. The graft was primarily dressed with a nonadherent dressing (Telfa Clear Wound Dressing, Covidien, Mansfield, MA), and then covered with a secondary dressing of mesh gauze (Xeroform Petrolatum Gauze, Covidien, Mansfield, MA), and an outer gauze dressing that was secured with a gauze roll dressing (Kerlix or Curity, Covidien, Mansfield, MA).
Prior to applying the keratinocyte suspension, the primary dressing was secured along the entire length of the dependent edge of the wound with a skin adhesive (Dermabond, Ethicon, Somerville, NJ) and staples. The cell suspension was then evenly sprayed starting at the dependent edge of the wound progressing steadily to the superior wound edge. As the suspension was sprayed, the primary dressing was lifted and the suspension was applied directly to the wound bed. Upon completion of coverage of the wound with the spray suspension, the primary dressing was secured on all edges with the skin adhesive and staples. The secondary dressing was applied over the primary dressing followed by a large gauze dressing secured by the previously noted gauze roll dressing. (Figures 4A-4E).
The outer dressings for the ACH and MSTSG sites were changed only for excessive drainage accumulation during the first postoperative week. On postoperative day 7, dressings were removed from both the ACH and MSTSG sites. The primary dressings were slowly lifted away from the wound. If the primary dressing had adhered to the wound bed, mineral oil was used to saturate the dressing to free it from the underlying bed. At this time, the percentage of reepithelialization and pigment and color match of the area were evaluated. All unhealed areas were redressed daily with a nonstick dressing and a topical antimicrobial ointment until fully healed. Following complete reepithelialization to the sites, topical antimicrobial therapy was discontinued and lotion was placed on the sites for skin hydration and compressive dressings for scar management. Patient follow-up evaluations were scheduled at postoperative weeks 1, 2, 3, 6, 12, and 52.
Follow-up visits on postoperative weeks 1, 2, 3, and 6 included assessment of the ACH and MSTSG sites for reepithelialization, pigmentation and color match, pain, and aesthetic appearance. Percentage of reepithelialization was evaluated by using a portable wound measurement device (Visitrak, Smith and Nephew, St. Petersburg, FL). All nonhealed areas were traced on the wound measurement grid and then the nonhealed area was calculated into square centimeters using the measurement device. All sites were compared for color and pigment match to immediately adjacent uninjured skin. Patients were asked to provide their objective assessments of pain as related to the ACH and MSTSG site.
At visits on postoperative weeks 12 and 52, all of the above evaluations were performed as well as objective assessments by the patient of the appearance of both treatment sites. A scar assessment of the ACH and MSTSG sites was performed using the Modified Vancouver Scar Scale (MVSS). Photographs were obtained of each treatment area at each visit.