Showing papers by "William G. Austen published in 2012"
TL;DR: In this controlled model of fat grafting with either a 5- or 3-mm aspiration cannulas, the use of a larger aspiration cannula led to improved graft retention and quality, which has important implications for clinical applications of fat transplantation.
Abstract: PURPOSE Autologous fat transfer ("fat grafting") is widely used in cosmetic and reconstructive surgery, but long-term outcomes remain inconsistent. Each step in the transfer process can cause mechanical damage to the graft tissue. In particular, liposuction breaks aspirated adipose tissue into distinct globules and subjects it to shear forces, both of which can impact subsequent fat graft viability. The optimal size of the liposuction cannula for use in fat grafting is not known. METHODS AND TECHNIQUES: Controlled lipoaspirate samples were collected from adult female patients undergoing elective liposuction of the abdomen and flanks with uniform aspiration pressure (-25 in Hg) and either a 3- or 5-mm standard blunt-tip liposuction cannula. Individual grafts of 1.00±(0.01) gram were prepared and injected into the bilateral flanks of nude mice with a 14-gauge catheter. After six weeks, these grafts were explanted and analyzed by weight and histology. RESULTS At six weeks, fat lobules in the 5-mm group retained 25% more weight than those in the 3-mm group [mean (SD), 0.70 (0.07) vs 0.56 (0.09) g, n=24/group, P<0.01). Histologic analysis revealed more intact, nucleated adipocytes in the 5-mm group than in the 3-mm group [4.42 (0.92) vs 3.10 (0.56) on a 1-5 rating scale]. The 5-mm group exhibited both less infiltrate [1.58 (0.17) vs 3.13 (0.70)] and less fibrosis [1.67 (0.45) vs 3.13 (0.89)] than the 3-mm group. CONCLUSIONS In this controlled model of fat grafting with either a 5- or 3-mm aspiration cannula, the use of a larger aspiration cannula led to improved graft retention and quality. This finding has important implications for clinical applications of fat grafting.
77 citations
TL;DR: Assessment of thrombin generation in patients undergoing abdominoplasty without deep venous thrombosis (DVT) chemoprophylaxis suggests abdominal contouring procedures induce a significant increase in the activity of the coagulation cascade that can be prevented by DVT prophylaxis.
Abstract: One of the most serious complications in plastic surgery is a thromboembolic event. However, little physiologic evidence exists to support the observed hypercoagulable state seen in contouring procedures. Twenty-one consecutive patients were enrolled prospectively to assess thrombin generation, which measures activity of the coagulation cascade, at baseline, intraoperative, and 24 hours after surgery. Compared with preoperative values, total thrombin generation increased by a mean of 997 nM intraoperatively (1.3-fold, P<0.004) and 1406 nM postoperatively (1.4-fold, P<0.001) in 9 patients undergoing abdominoplasty without deep venous thrombosis (DVT) chemoprophylaxis. The mean thrombin generation did not significantly change during or after surgery in 12 patients who received heparin for DVT prophylaxis (P=0.3). Thrombin generation was significantly less in patients receiving chemoprophylaxis compared with those who received no prophylaxis (P<0.01). This suggests abdominal contouring procedures induce a significant increase in the activity of the coagulation cascade that can be prevented by DVT chemoprophylaxis.
17 citations
TL;DR: This novel method utilizing automated cell counters can more accurately identify the viable adipocyte population without the limitations of traditional cell counting and the use of carboxymethyl cellulose and formalin in the preparation process can decrease variability and stabilize cell counts over time.
Abstract: BACKGROUND Fat grafting bench research is difficult because many traditional endpoints cannot be used reliably with adipocytes. Manual cell counting with trypan blue is a common method of measuring cell viability. There are, however, multiple known limitations, including human error, inability to analyze cell size, overestimation of adipocyte viability, and labor intensity. In this study, the authors demonstrate the effectiveness of an improved method of accurate adipocyte analysis using an automated cell counter. METHODS Human lipoaspirate was obtained, centrifuged, and digested. Samples were analyzed using a hemocytometer and an automated cell counter with two viability dyes. Results were then optimized by novel methods of preparation using carboxymethyl cellulose and formalin. RESULTS Manual trypan blue cell counts ranged from 2,750,000 to 19,200,000 live cells/ml. Automated cell counts significantly reduced variability (3,230,000 to 4,290,000 cells/ml). Counting cells between 40 and 150 μm, which is more specific to adipocytes, yielded 1,040,000 to 1,420,000 viable cells/ml. Using a second viability dye, CellTiter Blue, cell counts ranged between 993,000 and 1,340,000 live cells/ml. Adding carboxymethyl cellulose substantially decreased sampling variability by 80 percent, and the use of formalin prevented the decrease in cell counts over 4 hours from 432,000 to 7,000 cells/ml. CONCLUSIONS This novel method utilizing automated cell counters can more accurately identify the viable adipocyte population without the limitations of traditional cell counting. In addition, the use of carboxymethyl cellulose and formalin in the preparation process can decrease variability and stabilize cell counts over time. This is an efficient, specific, and reliable method of adipocyte analysis.
9 citations
TL;DR: Results: 1952 immediate implant-based reconstructions were performed in 1241 patients and patients who failed to clear infection medically had a higher average wbc and higher absolute wbc >10,000 and there was no difference in ADM usage.
Abstract: results: 1952 immediate implant-based reconstructions were performed in 1241 patients. 99 (5.1%) reconstructions were admitted for infection. These patients had a higher incidence of smoking (p<0.01), chemotherapy (p<0.01) and radiation (p<0.001). There was no difference in age, BMI, or acellular dermal matrix (ADM) usage. With intravenous antibiotics, 25 (25.3%) reconstructions cleared infection while 74 (74.7%) underwent attempted operative salvage (18) or explant (56). Patients who failed to clear infection medically had a higher average wbc (p<0.002) and higher absolute wbc >10,000 (p<0.03). There was no difference in ADM usage.
5 citations
TL;DR: Changing patterns of reconstruction over the last decade to accommodate increased case volume and decreased morbidity associated with reconstruction were accommodated through increased single-staged and prosthesis-based procedures.
Abstract: Increased bilateral mastectomy for breast cancer treatment has generated an increased demand for bilateral breast reconstruction. This study examines changing patterns of reconstruction over the last decade to accommodate increased case volume and decreased morbidity associated with reconstruction. A single institution series of 3171 consecutive breast reconstruction cases of more than 10 years was divided into 2 periods, that is, 1999 to 2004 and 2005 to 2010. Bilateral breast reconstruction case volume increased 260% from 1999 to 2004 (n = 237) to 2005 to 2010 (n = 634). Mean patient age at diagnosis decreased by 7 years (P < 0.001). In 2005 to 2010, autologous reconstruction decreased from 60% to 26%, implant-based reconstruction increased from 40% to 74%. There was a noted increase in single-stage implant reconstruction and selective application of perforator flaps for bilateral autologous reconstruction (P < 0.001). Two-staged tissue expander reconstruction accounted for the greatest share of total cost (45%) in the later period. A younger patient demographic and increased case volume were accommodated through increased single-staged and prosthesis-based procedures.
4 citations
TL;DR: Lipoaspirate was obtained and positive pressure was applied up to 6 atmospheres for up to 3 minutes and then injected into nude mice and the fat grafts were analyzed for weight and histology.
Abstract: Methods: Negative Pressure: Liposuction was performed in the laboratory on panniculectomy specimens. Suction pressure was either -15 inches Hg (-0.5 atmosphere) or -25 inches Hg (-0.83 atmosphere). Lipoaspirate was centrifuged at 1200G and injected into the flanks of nude mice. Positive Pressure: Lipoaspirate was obtained and positive pressure was applied up to 6 atmospheres for up to 3 minutes and then injected into nude mice. Shear Stress: Lipoaspirate was centrifuged at 1200G for 3 minutes and then injected at two different speeds: fast flow rate (3-5 cc/sec) versus slow flow rate (0.5-1 cc/sec). After 4 weeks, the fat grafts were analyzed for weight and histology.