Evan N. Vidar

ANALYSIS OF RISK FACTORS ASSOCIATED WITH MICROVASCULAR FREE FLAP FAILURE USING A MULTI-INSTITUTIONAL DATABASE

There are numerous factors that may contribute to microvascular free flap failure. Although technical issues are dominant factors, patient and clinical characteristics are also contributory. The aim of this study was to investigate non‐technical variables associated with microsurgical free flap failure using a multi‐institutional dataset.

Risk factors associated with venous thromboembolism in 49,028 mastectomy patients

Venous thromboembolism (VTE) is a potentially preventable disease that carries significant morbidity and mortality. Although malignancy is associated with increased risk for VTE, it varies according to cancer type. Despite the fact that breast cancer is the most common form of cancer in women, the incidence and risk factors associated with VTE in patients undergoing mastectomy have not been well characterized. To address this we utilized the ACS-NSQIP database to identify and characterize independent risk factors for VTE in 49,028 mastectomy patients. We identified 116 cases of VTE in the 49,028 cases analyzed (0.23%). Obesity (BMI > 30, OR = 1.91, p < 0.001), inpatient status (OR = 3.75, p < 0.001), venous catheterization (OR = 2.67, p = 0.012), prolonged operative time >3 h (OR = 4.36, p < 0.001), and immediate reconstruction (OR = 3.23, p < 0.001) were found to be independent risk factors for VTE. While the incidence of VTE is rare in mastectomy patients, the heightened awareness and increased VTE prophylaxis should be considered in high risk groups.

Effect of immediate reconstruction on postmastectomy surgical site infection.

Introduction:Surgical site infections (SSI) are a source of significant postoperative morbidity and cost. Although immediate breast reconstruction after mastectomy has become routine, the data regarding the incidence of SSI in immediate breast reconstruction is highly variable and series dependent. Methods:Using the National Surgical Quality Improvement Program database, all female patients undergoing mastectomy, with or without immediate reconstruction, from 2005 to 2009 were identified. Only “clean” procedures were included. The primary outcome was incidence of SSI within 30 days of operation. Stepwise logistic regression analysis was used to identify risk factors associated with SSI. Results:A total of 48,393 mastectomies were performed during the study period, of which 9315 (19.2%) had immediate breast reconstruction. The incidence of SSI was 3.5% (330/9315) (95% CI [confidence interval]: 3.2%–4%) in patients undergoing mastectomy with reconstruction and 2.5% (966/39,078) (95% CI: 2.3%–2.6%) in patients undergoing mastectomy without reconstruction (P < 0.001). Independent risk factors for SSI include increased preoperative body mass index (BMI), heavy alcohol use, ASA (American Society of Anesthesiologists) score greater than 2, flap failure, and operative time of 6 hours or longer. Conclusions:Immediate breast reconstruction is associated with a statistically significant increase in risk of SSI in patients undergoing mastectomy (3.5% vs 2.5%). However, this difference was not considered to be clinically significant. In this large series, increased BMI, alcohol use, ASA class greater than 2, flap failure, and prolonged operative time were associated with increased risk of SSI.

Incidence of surgical-site infection is not affected by method of immediate breast reconstruction.

Background: To date, few large-scale studies have reported the incidence of surgical-site infection in women undergoing mastectomy with respect to the various methods of immediate breast reconstruction. This study assessed whether the reconstruction method was associated with the risk of surgical-site infection in these patients. Methods: Using the National Surgical Quality Improvement Program database, 9230 female patients undergoing mastectomy with immediate reconstruction from 2005 to 2009 were identified. Reconstruction was classified as autologous, prosthetic, or hybrid. The primary outcome was the incidence of surgical-site infection within 30 days of operation. Univariate and multivariate analyses were performed to derive the unadjusted and adjusted risk of surgical-site infection according to reconstruction method. Results: The overall rate of surgical-site infection was 3.53 percent (95 percent CI, 3.15 to 3.94 percent), with individual rates of 3.33 percent (95 percent CI, 2.93 to 3.76 percent) for prosthetic reconstruction, 4.88 percent (95 percent CI, 3.48 to 6.11 percent) for autologous reconstruction, and 2.19 percent (95 percent CI, 0.88 to 4.45 percent) for hybrid reconstruction. The adjusted odds ratio of surgical-site infection was 1.14 (95 percent CI, 0.83 to 1.58; p = 0.42) for autologous versus prosthetic methods and 0.59 (95 percent CI, 0.27 to 1.27; p = 0.18) for hybrid versus prosthetic methods. Conclusions: Although the risk of surgical-site infection in patients undergoing immediate reconstruction is highest with autologous and lowest with hybrid methods of reconstruction, the difference in infection risk was not statistically significant after adjustment for confounding factors. Thus, all methods of reconstruction are viable options with regard to risk for surgical-site infection. CLINICAL QUESTION/LEVEL OF EVIDENCE: Risk, III.

Is Presurgical Nasoalveolar Molding Therapy More Effective in Unilateral or Bilateral Cleft Lip-Cleft Palate Patients?

Background: The purpose of this study was to compare the efficacy of presurgical nasoalveolar molding in treating unilateral versus bilateral cleft lip–cleft palate patients. Methods: A blinded, retrospective study was conducted with 16 unilateral and 13 bilateral cleft lip–cleft palate patients. Pretreatment and posttreatment facial and intraoral impressions were used to compare soft- and hard-tissue changes. Results: Nasoalveolar molding therapy improves nasal angle in unilateral (p = 0.010) and bilateral cleft lip–cleft palate (p = 0.001) patients, and improves nostril width in unilateral (p = 0.005) and bilateral cleft lip–cleft palate (p = 0.028) patients. Treatment significantly improves nostril breadth only in unilateral cleft lip–cleft palate patients (p = 0.005). Compared with bilateral cleft lip–cleft palate patients, unilaterally affected patients were more asymmetric before and after nasoalveolar molding therapy. Nasoalveolar molding more effectively increases columellar height (p = 0.002) and columellar width (p = 0.002) in the bilateral cleft lip–cleft palate group. Although starting bialar widths did not significantly differ between the two groups, nasoalveolar molding significantly decreased bialar width only in unilateral cleft lip–cleft palate patients (p = 0.032). When the intersegment alveolar cleft distances of the bilateral cleft lip–cleft palate patients were summed, an improvement similar to that in unilateral cleft lip–cleft palate patients was observed. Furthermore, nasoalveolar molding appeared to prevent alveolar width widening as patients continued to grow. Conclusions: There are differences in efficacy between unilateral and bilateral cleft lip–cleft palate patients undergoing nasoalveolar molding. Understanding these differences may help physicians and dentists better shape expectations.

Lentiviral transduction of face and limb flaps: Implications for immunomodulation of vascularized composite allografts

Background: Ex vivo introduction of an immunomodulatory transgene into a face or hand allograft may improve the risk-to-benefit ratio of vascularized composite allografts. Abrogation of the immunogenicity of the skin component of a face or hand allograft may decrease alloreactivity and permit the induction of immunologic tolerance. Proof-of-principle demonstrations of transduction of composite tissue have been established using adenoviral vectors, producing transient gene expression. The authors hypothesized that transduction, integration, and long-term expression of transgenes in a vascularized composite allograft could be achieved using lentiviral vectors. Methods: Ex vivo transduction of heterogeneous primary rat cell lines representative of a composite tissue flaps cellular architecture was performed using a luc–enhanced green fluorescent protein (eGFP) human immunodeficiency virus-1–based lentiviral vector. Ex vivo injections of rat superficial inferior epigastric artery flaps with the viral vector were performed intraarterially, intramuscularly, and intradermally. Results: Quantifiable reporter expression by flow cytometry (fluorescence-activated cell sorting) analysis and in vitro bioluminescence was observed. The luc-eGFP vector exhibited broad tropism and allowed transgene expression in relevant cell lines and throughout the flaps. Ex vivo intradermal transfection resulted in genomic integration and long-term constitutive gene expression (>150 days). Similarly, efficient intradermal transfection of face and hand flaps in a rat model corroborated this approach. Ex vivo intravascular perfusion of the vector proved inferior to intradermal injection. Conclusions: Intradermal delivery of the transgenes proved superior to intravascular perfusion. Optimization of this gene-delivery approach may allow long-term, constitutive expression of immunomodulatory proteins in face and hand allografts. Future goals include replacement of the luciferase and eGFP reporter genes with key immunomodulatory proteins.