The fluid dynamics of simultaneous irrigation with negative pressure wound therapy.

Saline irrigation has been shown to be both experimentally and clinically efficacious in decreasing bacterial contamination as well as decreasing infection rates. The dynamics of irrigation delivery fall into two primary categories: simultaneous and intermittent irrigation. An important component to irrigation therapy is distribution of irrigation solution to hard-to-reach areas of a wound bed, including undermining and fissure-like structures. Here we test the effectiveness of simultaneous irrigation to fill the irregular structures of a wound bed. In order to visualise the dynamic movement of irrigation solution, three-dimensional wound models were constructed using clear synthetic ballistic gel. Wounds with the aforementioned characteristics were carved into the ballistic gel with varying area, depth and volume. All three wounds were dressed as per manufacturer's instructions. Data demonstrate that simultaneous irrigation is effective in reaching all parts of a wound bed in wound models that have both undermining and tunnelling, and irrigation effectively saturates bridged wounds. Finally, this study shows that there is constant turnover of irrigation solution in the wound that is driven more by administration volume and less by flow rate. These data show that simultaneous irrigation is an effective technique for delivering irrigation solution to both simple and complex wounds.

Delay in unipedicled TRAM flap reconstruction of the breast: a review of 76 consecutive cases.

Since its introduction in 1982, the transverse rectus abdominis musculocutaneous (TRAM) flap has become the standard therapy in autogenous breast reconstruction. A lower rate of partial flap (fat) necrosis is associated with microvascular free-flap transfer compared with the conventional (unipedicled) TRAM flap because of its potentially improved blood supply. A TRAM flap delay before flap transfer has been advocated, especially in a high-risk patient population (obesity, history of cigarette smoking, radiation therapy, or abdominal scar). The authors reviewed a series of 76 consecutive delayed unipedicled TRAM flap breast reconstructions during a 5-year period. Data were analyzed with respect to type of procedure and time of delay, overall outcome, general surgical complications, flap-related (specific) complications (partial or complete flap loss), and patient satisfaction. Seventy-six unilateral breast reconstructions using the unipedicled TRAM flap were performed between 1995 and 2000 in 76 patients (mean age, 47.4 years). Fifty-four flaps were performed as immediate reconstructions, and 22 as secondary procedures. Seventy-two flaps were based on the contralateral pedicle, and four flaps were based on an ipsilateral pedicle. In all cases, a flap delay consisted of ligature of both deep inferior epigastric arteries and veins, accessed from an inferior flap incision down to the fascia, with a mean of 13.9 days before the flap transfer. No acute flap take-back procedure had to be performed. There was no complete flap loss, and breast reconstruction was achieved in all cases. In five cases (6.6 percent), a partial (fat) flap necrosis occurred. Interestingly, the majority of these cases (four of five) were secondary breast reconstructions. In addition, of the five patients who had partial flap necrosis, four had a history of smoking, two received radiation therapy, three received chemotherapy, and three patients were obese (body mass index greater than or equal to 30) or overweight (body mass index greater than or equal to 25). In three cases, an early surgical complication (two wound infections at the flap interface and one at the donor site) occurred. One patient developed a deep vein thrombosis. Five patients developed secondary ventral hernias necessitating repair (6.6 percent). Forty-one patients underwent secondary nipple-areola reconstruction. In 19 patients of this group, a secondary procedure (e.g., scar revision, limited liposuction, and/or excision of contour deformities) was simultaneously performed. A survey of patient satisfaction was performed using a modified SF-36 questionnaire. Fifty-one patients participated (67 percent). The overall satisfaction was very high and 51 patients reported that they would recommend the procedure to others (100 percent). Multiple factors such as patient selection, surgical expertise, and preoperative and postoperative management contribute to the success of any type of autogenous breast reconstruction. However, rare partial and absent complete flap necrosis in the authors' series may be attributable to the flap delay. A low morbidity rate and short hospital stay may become increasingly relevant, with limited structural and financial resources in the future. Therefore, the delayed unipedicled TRAM flap should be regarded as a valuable option in attempted breast reconstruction using autogenous tissue in both a high-risk and the general patient population.

Immunohistochemical identification of vascular endothelial growth factor in pig latissimus dorsi musculocutaneous flaps following ischemia-reperfusion injury.

Vascular Endothelial Growth Factor (VEGF), a potent angiogenic, mitogenic and vascular permeability enhancing protein, appears to improve survival of ischemic flaps independent of its route of administration. The purpose of this study was to examine VEGF protein expression in biopsies of surgical flaps with immunohistochemical techniques. In 6 male Yorkshire-type pigs, 10 cm x 15 cm Latissimus dorsi musculocutaneous flaps were elevated bilaterally. Flap zones I, II, and III were established according to their distance from the vascular pedicle. After isolation of the thoracodorsal artery and vein, one flap was randomly assigned to ischemia by temporary occlusion of the vascular pedicle. Ischemia (4 hours) was followed by 2 hours of reperfusion (ischemia group, n = 6). The contralateral (nonischemic) flap served as a control (control group, n =6). Skin and muscle biopsies of flaps were taken at the end of the protocol for immunohistochemical staining using a VEGF antihuman monoclonal antibody. Epidermis of flap skin did not demonstrate VEGF-positive staining, but the dermis and subcutaneous tissue did. Muscle components of biopsies demonstrated staining of interfascicular septa and staining of myocytes. A semi-quantitative scoring system with a scale of 0 to 3 was used for grading of immunohistochemical staining. In skin, areas adjacent to the flap showed an overall mean VEGF staining score of 0.7. All zones of ischemic flaps showed increased mean immunohistochemical staining for VEGF (scores = 1.2, 1.6, and 1.4 in zones I, II, and III, respectively). In muscle, however, only zone I showed increased VEGF immunohistochemical staining from 0.7 in adjacent areas to 1.7 in ischemic flaps. The results indicate only moderate endogenous up-regulation of VEGF in flaps, supporting the utilization of exogenous VEGF as an adjunct in microsurgical therapy.