Vacuum-assisted closure in the treatment of sternal wound infection after cardiac surgery

Aim: Vacuum-assisted closure (VAC) was primarily designed for the treatment of pressure ulcers or chronic, debilitating wounds. Recently, VAC has become an encouraging treatment modality for sternal wound infection after cardiac surgery, providing superior results to conventional treatment strategies. Methods: From November 2004 to September 2006, 34 patients, undergoing VAC therapy for sternal wound infection following cardiac surgery, were prospectively evaluated. Ten patients (29 %) were treated for superficial sternal wound infection and 24 (71 %) for deep sternal wound infection. The median age was 69.9 years (range 48 to 82) and the median BMI was 33.4 kg/m(2) (range 28 to 41). Twenty patients (59 %) were women and 19 patients (59 %) were diabetics. Owing to sternal wound infection complications, 16 patients (47 %) were readmitted to the department. VAC was used following the previous failure of the conventional treatment strategy in 7 patients (21 %). Results: Thirty-three patients (97 %) were treated successfully. One patient (3 %) died of multiple organ failure. The overall length of hospitalization was 34.6 days (range 9 to 62). The median number of dressing changes was 4.6 (range 3 to 10). The median VAC treatment time until surgical closure was 9.2 days (range 6 to 21 days). VAC therapy was solely used as a bridge to definite wound closure. Three patients (9 %) with chronic fistula were re-admitted 1 to 6 months after VAC therapy. Conclusions: VAC therapy is a safe and reliable option in the treatment of sternal wound infection in cardiac surgery. VAC therapy should be considered an effective adjunct to conventional treatment modalities for the treatment of extensive and life-threatening wound infections following cardiac surgery, particularly in the presence of risk factors.     

Vacuum-assisted closure for the treatment of degloving injuries

Degloving injuries of the hand and foot pose difficult reconstructive and rehabilitation challenges. After an excellent experience with split-thickness skin grafting with the vacuum-assisted closure device, we began studies with full-thickness skin grafts and traumatized skin. The device has been used with successful reapplication of full-thickness degloved skin in two patients. The first patient suffered degloving of the foot; the second patient, degloving of the hand.     

Suture materials and other factors associated with tissue reactivity, infection, and wound dehiscence among plastic surgery outpatients

The most common complications in plastic surgery are tissue reactivity, infections, and wound dehiscence. In the literature, there are only a few studies with sample sizes large enough and methods of statistical analysis appropriate for evaluating the role of suture materials in inducing such complications. In the 1000 plastic surgery outpatients in this study, the association of different suture materials, individual patient characteristics, surgeon skill, and wound site and length with postoperative wound complications (i.e., tissue reactivity, infection rate, and wound dehiscence) were investigated. No substantial differences were found between the different suture materials and suturing techniques. A moderate increase in the risk of tissue reactivity for silk and polyglactin 910 and a protective effect of thinner internal sutures were observed. In multivariate analysis, such differences were not statistically significant. Male sex [odds ratio (OR), 1.7; 95 percent confidence interval (CI), 1.06 to 2.72] and older age (OR, 2.34; 95 percent CI, 1.36 to 4.05) were found to be the most important risk factors for tissue reactivity and infection rate (male sex: OR, 5.1; 95 percent CI, 1.7 to 15.9; older age: OR, 5.6; 95 percent CI, 1.9 to 16), whereas younger age was associated with an increased risk of dehiscence (OR, 3.06; 95 percent CI, 1.41 to 6.65). Wounds on the lower limbs showed a lower risk of tissue reactivity and wounds on the back a higher risk of dehiscence. Wound length was associated with the risk of tissue reactivity in one-layer sutures (OR, 2.92; 95 percent CI, 1.51 to 5.65). An increased risk of both tissue reactivity (OR, 1.53; 95 percent CI, 1.03 to 2.27) and dehiscence (OR, 2.44; 95 percent CI, 1.1 to 5.43) was observed for operations performed by less-experienced surgeons. Rather than factors related to suture materials and different surgical techniques, and with the exception of surgeon experience, general characteristics of the patients (i.e., sex and age) and of the wounds (i.e., length and site) seemed to be primarily responsible for local wound complications.     

A morphoelastic model for dermal wound closure

We develop a model of wound healing in the framework of finite elasticity, focussing our attention on the processes of growth and contraction in the dermal layer of the skin. The dermal tissue is treated as a hyperelastic cylinder that surrounds the wound and is subject to symmetric deformations. By considering the initial recoil that is observed upon the application of a circular wound, we estimate the degree of residual tension in the skin and build an evolution law for mechanosensitive growth of the dermal tissue. Contraction of the wound is governed by a phenomenological law in which radial pressure is prescribed at the wound edge. The model reproduces three main phases of the healing process. Initially, the wound recoils due to residual stress in the surrounding tissue; the wound then heals as a result of contraction and growth; and finally, healing slows as contraction and growth decrease. Over a longer time period, the surrounding tissue remodels, returning to the residually stressed state. We identify the steady state growth profile associated with this remodelled state. The model is then used to predict the outcome of rewounding experiments designed to quantify the amount of stress in the tissue, and also to simulate the application of pressure treatments.     

Intraoral wound closure with tissue-engineered mucosa: new perspectives for urethra reconstruction with buccal mucosa grafts

In urethra reconstruction, the creation of a new urethra from a free oral mucosa graft is an established surgical technique. The oral mucosa is removed at the same time that the urethra reconstruction procedure is performed. Depending on the size of graft required, the intraoral wound is closed primarily or left to heal secondarily. The latter method limits this technique by leading to scars or strictures, which have a negative impact on the condition of the intraoral soft tissue. Therefore, in this study, a pilot study involving 12 patients, tissue-engineered mucosa was tested for covering intraoral defects to avoid the drawbacks mentioned above. For mucosa tissue-graft engineering, a biopsy sample 2 to 4 mm in diameter was removed from the hard palate approximately 4 weeks before the urethra reconstruction procedure was to be performed. In addition, 30 ml of autogenous serum was extracted from a venous whole-blood sample. The primary cultures were incubated in Dulbecco modified Eagle's medium and nutrient factor F 12 (Gibco Co., Eggenstein, Germany), containing the usual additives and autogenous serum. After a period of 3 weeks, subcultivation was performed to engineer mucosa transplants consisting of several layers of keratinocytes on a support foil. After thorough intraoperative blood coagulation had occurred, the cultured mucosa graft on the carrier foil was applied on the wound surface and fixed by single sutures. Additionally, the cultured mucosa graft was covered for 8 to 10 days by an intraoral dressing, which was also fixed onto the wound surface by single suture loops. It is possible to perform primary intraoral wound closure with tissue-engineered mucosa to cover defect sizes as large as 11.0 x 4.0 cm. This new method provides a better prospect for both urethra reconstruction and the reconstruction of intraoral tissue defects. The number and size of intraoral scars and strictures are diminished. This is of special interest for the reconstruction of the functional unit oral cavity, including soft tissue and cosmetic conditions (e.g., in case of prosthetic rehabilitation). In comparison to primary wound closure with local tissue, the technique presented in this study reduces the severity of postoperative pain and allows faster rehabilitation in patients because of a better wound-healing process. Furthermore, better mobility of intraoral soft tissue structures is achieved.     

Risks associated with "components separation" for closure of complex abdominal wall defects

The reconstruction of complex abdominal wall defects can often pose a significant challenge to surgeons and their patients. Complex ventral hernias may result from large tumor resections, trauma from gunshot wounds, or infections following routine abdominal surgery. "Components separation" of the abdominal musculature uses advancement of local autologous tissue, when available, to close large ventral wall defects. The authors report on a retrospective chart review of 30 patients who underwent components separation for the closure of complex abdominal defects. The study group was 50 percent female, with a mean age of 45 years, body mass index of 33.2 kg/m2, and abdominal defect size of 240 cm2. On average, 20 percent of patients had preoperative wound infections, 30 percent had intraoperative bowel enterotomies, and 33 percent required prosthetic mesh for closure. Total surgery time averaged 4.8 hours, with a mean postoperative stay of 12.5 days and follow-up of 9.5 months. The recurrence rate was 10 percent; postoperative complications included midline ischemia, infection, and dehiscence occurring at rates of 20, 40, and 43 percent, respectively. This study provides a comprehensive review of the risks and complications associated with the treatment of complex ventral hernias and those associated with abdominal "components separation."     

A new classification for the standardization of nomenclature in free flap wound closure

A profusion of terms are currently used to describe free flap wound closure. It is important to broadly standardize nomenclature when embarking on a comparison of functional outcomes between institutions. Therefore, a series of 68 "emergency" (within 24 hours) free flaps performed by a single surgeon were reviewed with respect to a total experience of 188 free tissue transfers to formulate a consistent nomenclature applicable to free flap wound closure in general. The nomenclature presented divides free flap closure into three categories: "primary free flap closure" (12 to 24 hours), "delayed primary free flap closure" (2 to 7 days), and "secondary free flap closure" (after 7 days). This system is analogous to the standard terms "primary," "delayed primary," and "secondary wound closure." It is consistent with known biologic and microbiologic principles of wound closure in general and should provide a simple basis for classifying free flap wound closure. Illustrative examples are presented to highlight the classification scheme.     

Shear stress enhances human endothelial cell wound closure in vitro

Repair of the endothelium occurs in the presence of continued blood flow, yet the mechanisms by which shear forces affect endothelial wound closure remain elusive. Therefore, we tested the hypothesis that shear stress enhances endothelial cell wound closure. Human umbilical vein endothelial cells (HUVEC) or human coronary artery endothelial cells (HCAEC) were cultured on type I collagen-coated coverslips. Cell monolayers were sheared for 18 h in a parallel-plate flow chamber at 12 dyn/cm(2) to attain cellular alignment and then wounded by scraping with a metal spatula. Subsequently, the monolayers were exposed to a laminar shear stress of 3, 12, or 20 dyn/cm(2) under shear-wound-shear (S-W-sH) or shear-wound-static (S-W-sT) conditions for 6 h. Wound closure was measured as a percentage of original wound width. Cell area, centroid-to-centroid distance, and cell velocity were also measured. HUVEC wounds in the S-W-sH group exposed to 3, 12, or 20 dyn/cm(2) closed to 21, 39, or 50%, respectively, compared with only 59% in the S-W-sT cells. Similarly, HCAEC wounds closed to 29, 49, or 33% (S-W-sH) compared with 58% in the S-W-sT cells. Cell spreading and migration, but not proliferation, were the major mechanisms accounting for the increases in wound closure rate. These results suggest that physiological levels of shear stress enhance endothelial repair.