Effect of liposuction on skin perfusion

Clinical reports of full-thickness skin necrosis have raised concern about the thermal and dermal ischemic effects of ultrasound-assisted liposuction. The purpose of this study was to evaluate skin perfusion in patients treated with ultrasound-assisted liposuction or suction-assisted liposuction. Patients (n = 75) were studied prospectively in the perioperative period surrounding their suction-assisted liposuction (31 patients) or ultrasound-assisted liposuction (64 patients). The laser Doppler flowmeter was used to monitor skin perfusion in the treated regions preoperatively, intraoperatively, and postoperatively at a series of time intervals. The effects of the anesthetic, wetting solution, and type of liposuction (suction-assisted liposuction or ultrasound-assisted liposuction) on skin perfusion were measured. Anesthetic induction significantly increased measured skin perfusion. Wetting solution infusion significantly decreased skin perfusion (-57.4 percent +/- 2.0) by 15 minutes postinfusion. Skin perfusion in the ultrasound-assisted liposuction group was significantly greater than that of the suction-assisted liposuction patients at 1 hour, 1 day, and 1 week postoperatively; however, by 2 to 5 weeks, no difference in skin perfusion was noted and skin perfusion had returned to preoperative levels in both groups. Although skin perfusion in the suction-assisted liposuction group was significantly lower than in the ultrasound-assisted liposuction group in the early postoperative period, no differences in skin perfusion between the groups were noted beyond 1 week postoperatively, suggesting that neither technique impairs perfusion.     

Comparative lipoplasty analysis of in vivo-treated adipose tissue

A comparative histologic and chemical analysis was undertaken of adipose tissue treated in vivo with traditional, ultrasound-assisted, and external ultrasound-assisted lipoplasty. A series of six healthy women undergoing elective liposuction according to the superwet technique using a 1:1 infiltration ratio with the estimated quantity of fat to be removed was included in the study. Four separate regions on each patient were treated independently in vivo with traditional liposuction, internal ultrasound-assisted liposuction, or external ultrasound-assisted liposuction for 7 minutes. External massage was used as a control. Four separate specimens of adipose tissue from each patient were assessed for cellular disruption using blinded histologic evaluation. The remainder of tissue was centrifuged to separate the aqueous phase from the cellular components and then spectrophotometrically analyzed for creatinine kinase and glycerol 3-phosphate dehydrogenase activity as markers of cellular disruption. Histologic analysis confirmed 70 to 90 percent cellular disruption with internal ultrasound-assisted liposuction. Suction-assisted and external ultrasound-assisted liposuction showed 5 to 25 percent disruption, whereas massage controls showed only 5 percent. Only internal ultrasound-assisted liposuction showed 5 to 20 percent thermal liquefaction. Absorbance analysis showed creatine kinase activity (sigma units) greatest in ultrasound-exposed tissue. Both external and internal ultrasound-assisted liposuction gave creatine kinase levels 28 to 33 percent greater than suction-assisted liposuction, which varied only 10 percent from controls. Glycerol 3-phosphate dehydrogenase activity was 44 percent greater for internal ultrasound-assisted liposuction than that detected with suction-assisted liposuction. Glycerol 3-phosphate dehydrogenase activity with external ultrasound-assisted liposuction and massage did not vary much from each other, at only 14 percent and 11 percent activity compared with internal ultrasound-assisted liposuction, respectively. Histologic and enzyme analysis of the different types of liposuction and their effect on adipocyte cellular disruption revealed no significant effect of external ultrasound or massage on the adipocytes. Further experimental studies are necessary to evaluate the role and efficacy of alternative techniques for body contouring.     

Is there evidence for excessive free radical production in vivo during ultrasound-assisted liposuction?

The surgical technique of ultrasound-assisted liposuction has become a standard procedure for the treatment of lipodystrophy. However, little is known about the impact of this therapy on fatty tissue on the molecular level. There are concerns about possible adverse effects related to the high-intensity ultrasound energy, because in vitro studies have shown a substantial generation of free radicals. In this study, the authors investigated whether ultrasound waves can create an excessive free radical production in vivo by measuring lipid peroxidation products in the form of malondialdehyde equivalents. For this purpose, the thiobarbituric acid-reactive substances (TBARS) assay was chosen. In this test, malondialdehyde, a major product of lipid peroxidation, reacts with thiobarbituric acid to produce a pink adduct that can be measured spectrophotometrically. The authors determined oxidation products in 28 aspirates of 17 treated patients before ultrasound-assisted liposuction (0 minutes) to establish a baseline concentration and at 2, 5, and 10 minutes after the treatment was begun. Median malondialdehyde concentration of the control group (conventional liposuction, 0 minutes) was 3.40 nmol of malondialdehyde per gram of adipose tissue. Median concentrations after 2, 5, and 10 minutes of ultrasound-assisted liposuction were 7.45 (n = 28), 8.84 (n = 21), and 4.07 (n = 8) nmol malondialdehyde per gram adipose tissue, respectively. The differences were not statistically significant. The data suggest that there is no excessive formation of lipid oxidation products in response to free radicals. The antioxidative capacity of adipose tissue does not seem to be overwhelmed by the standard application regimen of ultrasound-assisted liposuction.     

Ultrasound-assisted lipoplasty treatment for axillary bromidrosis: clinical experience of 375 cases

Bromidrosis is a condition of abnormal offensive body odor caused mostly by apocrine gland secretion from the axilla. Although no morbid sequelae are known, the odor can be disturbing enough to cause social impairment and psychological distress. Medical care is available but is temporary and yields limited clinical benefit. Surgical treatment may provide a more definite remedy through reduction of the apocrine gland. However, there are risks for complication following surgical treatment such as subdermal excision, subcutaneous shaving, en bloc excision, and liposuction. The search for a less invasive but still effective procedure has led the authors to use ultrasound-assisted liposuction, which has reduced the risk of complication and recurrence. The purpose of this article was to evaluate the long-term outcome of ultrasound-assisted liposuction for the treatment of bromidrosis. From August 1998 to September 2002, 375 consecutive patients underwent ultrasound-assisted liposuction for bromidrosis of the axilla. The average age of the patients was 25.7 years (range, 15 to 55 years) and the average follow-up period was 18.8 months (range, 7 to 56 months). Subjective complaints of recurrences were noted in 22 patients (5.9 percent) and secondary ultrasound-assisted liposuction was performed, resulting in no further complaints. Complications other than recurrences were mild skin sloughing (3.2 percent), hematoma (1.3 percent), subcutaneous band (0.3 percent), and hypesthesia of the hand (0.3 percent), all of which healed spontaneously. Through a questionnaire that was answered by 264 patients, a subjective satisfaction rate was measured. Among the completed questionnaires, 91.7 percent reported satisfactory reduction of odor. Ultrasound-assisted liposuction to treat bromidrosis of the axilla provides advantages such as rapid recovery, less restriction of movement, unnoticeable scars, and a low rate of recurrence. The long-term outcome supports the benefits of this procedure. The authors recommend the use of ultrasound-assisted liposuction as first-line treatment for bromidrosis of the axilla.     

Classification and management of gynecomastia: defining the role of ultrasound-assisted liposuction

Gynecomastia, or excessive male breast development, has an incidence of 32 to 65 percent in the male population. This condition has important physical and psychological impacts. Advances in elucidating the pathophysiology of gynecomastia have been made, though understanding remains limited. Recommendations for evaluation and workup have varied and are often arbitrary. A diagnostic algorithm is suggested, with emphasis on a comprehensive history, physical examination, and minimizing unnecessary diagnostic testing. Medical management has had limited success; surgical therapy, primarily through excisional techniques, has been the accepted standard. Although effective, excisional techniques subject patients to large, visible scars. Ultrasound-assisted liposuction has recently emerged as a safe and effective method for the treatment of gynecomastia. It is particularly efficient in the removal of the dense, fibrous male breast tissue while offering advantages in minimal external scarring. A new system of classification and graduated treatment is proposed, based on glandular versus fibrous hypertrophy and degree of breast ptosis (skin excess). The authors' series of 61 patients with gynecomastia from 1987 to 2000 at the University of Texas Southwestern Department of Plastic Surgery demonstrated an overall success rate of 86.9 percent using suction-assisted lipectomy (1987 to 1997) and ultrasound-assisted liposuction (1997 to 2000). The authors have found ultrasound-assisted liposuction to be effective in treating most grades of gynecomastia. Excisional techniques are reserved for severe gynecomastia with significant skin excess after attempted ultrasound-assisted liposuction.     

Blood loss in major liposuction procedures: a comparison study using suction-assisted versus ultrasonically assisted lipoplasty.

The blood loss that accompanies liposuction procedures has always been a concern. Tumescent injection of the targeted area of liposuction with dilute lidocaine and epinephrine solution has minimized intraoperative blood loss. Proponents of a newer ultrasonically assisted lipoplasty technique have claimed many benefits over traditional suction-assisted lipoplasty. However, few quantitative data are available on the intraoperative blood loss and the significance of postoperative anemia using the ultrasonic method. A prospective clinical observational design was used to investigate 38 patients undergoing suction-assisted lipoplasty and 37 patients undergoing ultrasound-assisted lipoplasty in whom the liposuction aspirate was expected to be more than 1000 ml. These patients were investigated with preoperative measurement of hemoglobin, platelet count, prothrombin time, partial thromboplastin time, and postoperative measurement of hemoglobin on the seventh postoperative day. In addition, hemoglobin concentration and whole blood volume were calculated from the infranatant portion of the liposuction aspirate. The mean +/- SD volume of the liposuction aspirate was 2901 +/- 1471 ml for suction-assisted compared with 2741 +/- 1086 ml for ultrasound-assisted lipoplasty. The mean +/- SD of whole blood volume in liposuction aspirate per case was 36 +/- 50.82 ml for suction-assisted lipoplasty and 36 +/- 28.62 ml for ultrasound-assisted lipoplasty. The mean +/- SD of the preoperative hemoglobin concentration was 13.93 +/- 0.99 g/dl for suction-assisted lipoplasty and 14.05 +/- 1.16 g/dl for ultrasound-assisted lipoplasty, whereas the mean +/- SD of the postoperative hemoglobin concentration was 13 +/- 1.42 g/dl for suction-assisted lipoplasty and 13.05 +/- 1.32 g/dl for ultrasound-assisted lipoplasty. The mean decrease in hemoglobin on the seventh postoperative day was 0.93 +/- 0.92 g/dl for suction-assisted lipoplasty and 1 +/- 0.64 g/dl for ultrasound-assisted lipoplasty. The volume of whole blood loss was estimated to be 12.4 ml in each 1000 ml of liposuction aspirate when using suction-assisted lipoplasty versus 13.1 ml when using ultrasound-assisted lipoplasty. All procedures were done under general anesthesia, and patients were discharged home on the same day. No blood transfusion was required. This study shows that blood loss using the ultrasonic technique is slightly higher, though insignificant, than when using suction. However, this study did not demonstrate a difference in the postoperative hemoglobin decrease between the two techniques.     

The effects of ultrasonic energy on peripheral nerves: implications for ultrasound-assisted liposuction

The integration of ultrasound-assisted liposuction with traditional suction-assisted lipoplasty has extended the role of liposuction in body contouring. Although there are ample data regarding the effects of ultrasound on peripheral nerves from studies with the Cavitron ultrasound surgical aspirator, there is little information concerning the effects of modern ultrasound body contouring equipment on neural tissue. This study was designed to evaluate the functional and histologic effects of ultrasound energy on rat peripheral nerves (sciatic nerves) using a commonly-used ultrasound-assisted liposuction generator. After the application of ultrasound to exposed rat sciatic nerves, operative magnification was used to assess any visible injury. The sciatic function index was serially measured to quantify immediate and long-term functional effects on the nerves. Our results showed immediate visible injury using low amplitude settings (level 6), but no functional evidence of injury until much higher settings were used (level 9). All animals in the groups with initial functional impairment had returned to normal or near-normal function at completion of the study (51 days). Histologic examination revealed no evidence of damage in the low amplitude groups. Histologic analysis of the high amplitude groups displayed diffuse infiltration of the nerve, with foamy histiocytes and an increased number of mast cells, consistent with remote neural injury followed by myelin breakdown and repair.     

Adipose tissue-derived mesenchymal stem cell yield and growth characteristics are affected by the tissue-harvesting procedure

BACKGROUND: Adipose tissue contains a stromal vascular fraction that can be easily isolated and provides a rich source of adipose tissue-derived mesenchymal stem cells (ASC). These ASC are a potential source of cells for tissue engineering. We studied whether the yield and growth characteristics of ASC were affected by the type of surgical procedure used for adipose tissue harvesting, i.e. resection, tumescent liposuction and ultrasound-assisted liposuction. METHODS: Frequencies of ASC in the stromal vascular fraction were assessed in limiting dilution assays. The phenotypical marker profile of ASC was determined, using flow cytometry, and growth kinetics were investigated in culture. ASC were cultured under chondrogenic and osteogenic conditions to confirm their differentiation potential. RESULTS: The number of viable cells in the stromal vascular fraction was affected by neither the type of surgical procedure nor the anatomical site of the body from where the adipose tissue was harvested. After all three surgical procedures, cultured ASC did express a CD34+ CD31- CD105+ CD166+ CD45- CD90+ ASC phenotype. However, ultrasound-assisted liposuction resulted in a lower frequency of proliferating ASC, as well as a longer population doubling time of ASC, compared with resection. ASC demonstrated chondrogenic and osteogenic differentiation potential. DISCUSSION: We conclude that yield and growth characteristics of ASC are affected by the type of surgical procedure used for adipose tissue harvesting. Resection and tumescent liposuction seem to be preferable above ultrasound-assisted liposuction for tissue-engineering purposes.     

The zones of adherence: role in minimizing and preventing contour deformities in liposuction

True body sculpting demands a three-dimensional artistic understanding of the anatomic and surgical adipose layers of the central trunk when performing circumferential liposuction. This is essential in preventing complications from both ultrasound-assisted and suction-assisted lipoplasty. The authors describe five zones of adherence that should be avoided to prevent contour deformities in the central trunk area when performing circumferential liposuction. The anatomy of the subcutaneous tissue of these five anatomic zones is reviewed and correlated radiographically with magnetic resonance imaging studies. Aesthetic and technical considerations required to properly liposculpt the central trunk are demonstrated by case analysis of primary and secon-dary liposuction patients. These cases also delineate how to prevent and/or minimize deformities after liposuction.     

Does the liposuction method influence the phenotypic characteristic of human adipose-derived stem cells?

Adipose-derived stem cells (ASCs) possess a high differentiation and proliferation potential. However, the phenotypic characterization of ASCs is still difficult. Until now, there is no extensive analysis of ASCs markers depending on different liposuction methods. Therefore, the aim of the present study was to analyse 242 surface markers and determine the differences in the phenotypic pattern between ASCs obtained during mechanical and ultrasound-assisted liposuction. ASCs were isolated from healthy donors, due to mechanical and ultrasound-assisted liposuction and cultured in standard medium to the second passage. Differentiation potential and markers expression was evaluated to confirm the mesenchymal nature of cells. Then, the BD LyoplateTM Human Cell Surface Marker Screening Panel was used. Results shown that both population of ASCs are characterized by high expression of markers specific for ASCs: cluster of differentiation (CD)9, CD10, CD34, CD44, CD49d, CD54, CD55, CD59, CD71 and low expression of CD11a, CD11c and CD144. Moreover, we have noticed significant differences in antigen expression in 58 markers from the 242 studied. Presented study shows for the first time that different liposuction methods are not a significant factor which can influence the expression of human ASCs surface markers.     

Electrolyte and plasma enzyme analyses during large-volume liposuction

Substantial fluid shifts occur during liposuction as wetting solution is infiltrated subcutaneously and fat is evacuated, causing potential electrolyte imbalances. In the porcine model for large-volume liposuction, plasma aspartate aminotransferase and alanine transaminase levels were elevated following liposuction. These results raised concerns for possible mechanical injury and/or lidocaine-induced hepatocellular toxicity in a clinical setting. The first objective of this human model study was to explore the effect of the liposuction procedure on electrolyte balance. The second objective was to determine whether elevated plasma aminotransferase levels were observed subsequent to large-volume liposuction. Five female volunteers underwent three-stage, ultrasound-assisted liposuction. Blood samples were collected perioperatively. Plasma levels of sodium, potassium, venous carbon dioxide, blood urea nitrogen, chloride, and creatinine were determined. Liver function analyte levels were measured, including albumin, total protein, aspartate aminotransferase, and alanine transaminase, alkaline phosphatase, gamma-glutamyl transpeptidase, and total bilirubin. To further define intracellular enzyme release, creatine kinase levels were measured. Mild hyponatremia was evident postoperatively (134 to 136 mmol/liter) in four patients. Hypokalemia was evident intraoperatively in all subjects (mean +/- SEM; 3.3 +/- 0.16 mmol/liter; range, 3.0 to 3.4 mmol/liter). Hypoalbuminemia and hypoproteinemia were observed throughout the study (baseline: 2.9 +/- 0.2 g/dl; range, 2.6 to 3.5 g/dl), decreasing to 10 to 40 percent 24 hours postoperatively (2.0 +/- 0.2 g/dl; range, 1.7 to 2.1 g/dl). Aspartate aminotransferase, alanine transaminase, and creatine kinase levels were significantly elevated after the procedure (190 +/- 47.1 U/liter, 50 +/- 7.7 U/liter, and 11,219 +/- 2556.7 U/liter, respectively) (p < 0.01). Release of antidiuretic hormone and even mildly hypotonic intravenous fluid infiltration have long been known to cause hyponatremia postoperatively. Intraoperative hypokalemia is associated with hypocarbia and respiratory alkalosis and the elevated epinephrine levels observed in the concurrent study. Factors having the greatest initial impact on diminished serum albumin and protein levels postoperatively are redistribution and hemodilution. Subsequent diminished viscosity may significantly affect postoperative hemodynamics. Elevated aspartate aminotransferase, alanine transaminase, and creatine kinase levels are associated with skeletal muscle injury, adipocyte lysis, and/or hepatic damage. Therefore, tissue injury is associated with large-volume liposuction as observed in several cellularly released enzymes. Future clinical studies are required to determine the degree of injury and specific tissues that are damaged or sensitive to mechanical trauma and/or drugs used in large-volume liposuction.     

External ultrasonic lipoplasty: an effective method of fat removal and skin shrinkage

External ultrasonic lipoplasty is an effective method for the removal of localized fat and the fat due to moderate obesity. The ultrasound is externally applied and transmitted through the skin surface. The acoustic waves are selectively absorbed by previously injected tumescent fluid and fat. It is the combination of this acoustic wave and ultrasound-induced fluid streaming that facilitates fat removal. Multiple, 2.5- to 3.7-mm incisions are made, through which standard thin (2.3 to 3.5 mm) suction lipectomy cannulae are used to aspirate the emulsified fat and oil. A major advantage of this procedure is that superficial subdermal liposuction can be used safely, which enhances the thoroughness of fat removal and the contraction of the overlying skin. A total of 160 consecutive patients successfully underwent this procedure. Recovery was rapid, and patients returned to full activities within 24 to 48 hours. The skin remained soft, with minimal to no bruising throughout the entire postoperative period. The problems seen with internal ultrasonic liposuction, such as end hits and skin burns, were avoided. The large incisions required for internal ultrasound liposuction were not necessary. Previous models of externally applied ultrasound support current observations of the safety of external ultrasound lipoplasty. Only one small seroma was seen. External ultrasound lipoplasty is a safe, effective, and low-cost method of ultrasound-assisted removal of localized fat and the fat due to moderate obesity. Physician and patient satisfaction is high.     

Cervicofacial rejuvenation using ultrasound-assisted lipectomy

This article discusses a technique of cervicofacial rejuvenation that involves ultrasound-assisted lipectomy. This method is indicated for those patients who might be early candidates for a rhytidectomy, and/or those with an adipose volume excess in the lower facial and cervical areas. The application of ultrasonic energy stimulates skin retraction and allows for the superficial fat to be more safely accessed than can be accomplished with conventional liposuction methods. This technique, along with a retrospective analysis of the first 26 cases treated with the technique, will be presented in this article.     

Pharmacokinetics and safety of lidocaine and monoethylglycinexylidide in liposuction: a microdialysis study

High doses of lidocaine are administered to patients undergoing liposuction. Monoethylglycinexylidide, the active metabolite of lidocaine, is 80 to 90 percent as potent as lidocaine, and its relative toxicity is approximately that of lidocaine. Monoethylglycinexylidide has not previously been measured in studies on lidocaine in liposuction. The aims of this study were to characterize systemic exposure to lidocaine and monoethylglycinexylidide and to measure lidocaine and monoethylglycinexylidide levels within the tissues. Five female volunteers between the ages of 29 and 40 years underwent liposuction. Lidocaine (1577 to 2143 mg, corresponding to 19.9 to 27.6 mg/kg) was infiltrated during the procedure. Levels of lidocaine and monoethylglycinexylidide in blood and lipoaspirate were assessed perioperatively. Tissue lidocaine and monoethylglycinexylidide levels were measured postoperatively using a microdialysis technique in vivo. The peak (maximal) concentration of lidocaine plus monoethylglycinexylidide was 2.2 to 2.7 microg/ml. Time to peak lidocaine plus monoethylglycinexylidide was 8 to 28 hours after infiltration began. Absorbed lidocaine was estimated to be 911 to 1596 mg; therefore, 45 to 93 percent (mean, 64 percent) of the infiltrated dose was ultimately absorbed. Lipoaspirate analysis showed that 9.1 to 10.8 percent (mean, 9.7 percent) of the infiltrated dose was removed during the procedure. Tissue lidocaine levels below 5 microg/ml were demonstrated from 4 to 8 hours postoperatively. The peak lidocaine plus monoethylglycinexylidide concentration was within safe limits in this group of subjects. Time to peak lidocaine plus monoethylglycinexylidide signifies a delayed peak and therefore a longer period of potential lidocaine toxicity than was originally thought. Microdialysis results demonstrated that tissue lidocaine levels may be subtherapeutic within 4 to 8 hours of the procedure. Investigation into factors controlling the resorption of lidocaine during liposuction is warranted in an effort to improve the duration of effect. Furthermore, considering the active metabolite monoethylglycinexylidide, longitudinal studies are necessary to determine whether improving the side effect profile of lidocaine by reducing the dose administered during liposuction may be possible without decreasing the perioperative analgesic effect.     

Improvements in cardiovascular risk profile with large-volume liposuction: a pilot study

In this study, the authors investigated the physiologic effects of the altered body composition that results from surgical removal of large amounts of subcutaneous adipose tissue. Fourteen women with body mass indexes of greater than > 27 kg/m2 underwent measurements of fasting plasma insulin, triglycerides, cholesterol, body composition by dual-energy x-ray absorptiometry (DXA), resting energy expenditure, and blood pressure before and after undergoing large-volume ultrasound-assisted liposuction.There were no significant intraoperative complications. Body weight had decreased by 5.1 kg (p < 0.0001) by 6 weeks after liposuction, with an additional 1.3-kg weight loss (p < 0.05) observed between 6 weeks and 4 months after surgery, for a total weight loss of 6.5 kg (p < 0.00006). Body mass index decreased from (mean +/- SEM) 28.8 +/- 2.3 to 26.8 +/- 1.5 kg/m2 (p < 0.0001). This change in body weight was primarily the result of decreases in body fat mass: as assessed by DXA, lean body mass did not change (43.8 +/- 3.1 kg to 43.4 +/- 3.6 kg, p = 0.80), whereas DXA total body fat mass decreased from 35.7 +/- 6.3 to 30.1 +/- 6.5 kg (p < 0.0001). There were significant decreases in fasting plasma insulin levels (14.9 +/- 6.5 mIU/ml before liposuction versus 7.2 +/- 3.2 mIU/ml 4 months after liposuction, p < 0.007), and systolic blood pressure (132.1 +/- 7.2 versus 120.5 +/- 7.8 mmHg, p < 0.0002). Total cholesterol, high-density lipoprotein cholesterol, plasma triglycerides, and resting energy expenditure values were not significantly altered after liposuction.In conclusion, over a 4-month period, large-volume liposuction decreased weight, body fat mass, systolic blood pressure, and fasting insulin levels without detrimental effects on lean body mass, bone mass, resting energy expenditure, or lipid profiles. Should these improvements be maintained over time, liposuction may prove to be a valuable tool for reducing the comorbid conditions associated with obesity.     

Large-volume liposuction: a review of 631 consecutive cases over 12 years.

Since the advent of epinephrine-containing wetting solutions and sophisticated fluid management techniques, increasingly larger and larger volumes of liposuction aspirations have been reported. Unfortunately, with these larger volumes of liposuction being routinely performed, greater rates of complications have also been reported, with the worst of these resulting in deaths. In a response to the increasing concerns over the safety of large-volume liposuction, a critical review of the senior author's own series has been performed to evaluate risks and benefits and to recommend guidelines for safe and effective large-volume liposuction. A retrospective chart review was performed on 631 consecutive patients who underwent liposuction procedures of at least 3000 cc total aspirate. All procedures were performed by the same senior surgeon between January of 1986 and March of 1998. Before September of 1996, traditional liposuction techniques were used. After September of 1996, ultrasound-assisted liposuction was performed. The superwet technique of fluid management was employed for all procedures performed after 1991. The particulars of the surgical and anesthetic techniques used are reviewed in the article. Data collection included preoperative patient demographics, preoperative and postoperative weights and measurements, and preoperative and postoperative photographs. Total aspirate volumes, fluid intakes, and fluid outputs were measured, and all complications were tallied. Average follow-up was 1 year.Results showed the majority of patients to be women, aged 17 to 74 years old. Of the preoperative weights, 98.7 percent were within 50 pounds of ideal chart weight. Total aspirate volumes ranged from 3 to 17 liters, with 94.5 percent of these under 10 liters. Fluid balance measurements showed an average of 120 cc/kg positive fluid balance at the end of the procedure, with none of these patients experiencing any significant fluid balance abnormalities. Cosmetic results were good, with a 2- to 6-inch drop from preoperative measurements, depending on the area treated. Ten percent of patients experienced minor skin contour irregularities, with most of these patients not requiring any additional surgical procedures. One year after surgery, 80 percent of patients maintained stable postoperative weights. No serious complications were experienced in this series. The majority of the complications consisted of minor skin injuries and burns, allergic reactions to garments, and postoperative seromas. The more serious complications included four patients who developed mild pulmonary edema and one patient who developed pneumonia postoperatively. These patients were treated appropriately and went on to have uneventful recoveries. The results show that large-volume liposuction can be a safe and effective procedure when patients are carefully selected and when anesthetic and surgical techniques are properly performed. Meticulous fluid balance calculations are necessary to avoid volume abnormalities, and experience is mandatory when performing the largest aspirations. Cosmetic benefits are excellent, and overall complication rates are low.     

Tumescent and dry liposuction of lower extremities: differences in lymph vessel injury

Lipectomy is a standard procedure in plastic surgery. Until now, however, there was no definite information about the influence of different liposuction techniques (tumescent versus dry liposuction) on the integrity of lymph collectors during this procedure. To study the effect of these liposuction techniques on the incidence of lymph vessel injury, postmortem lymphatic preparations were done in nine human cadavers (18 lower extremities). Conventional liposuction with a blunt 4-mm cannula in the dry technique (n = 29 regions) was compared with the tumescent technique (n = 26). Liposuction was performed in parallel to the superficial lymph vessels (longitudinal suction) or transversally in an 80-degree to 90-degree angle to the extremity (vertical suction). Careful surgical preparation of different regions followed. A specific macroscopic lymph vessel injury score was applied to differentiate three degrees of lymph vessel lesions according to the extravasation of patent blue. In all lower extremities, postmortem lymph flow occurred as indicated by patent blue staining of the lymph vessels. Injection of fluid that is obligatory during tumescent suction did not result in grade 2 injury. On the contrary, tumescent suction overall produced significantly fewer lymph vessel lesions when compared with the dry technique (p < 0.05). Longitudinal liposuction produced significantly less injury when compared with vertical suction (p < 0.05). Tumescent suction and dry suction were equally effective in removing adipose aspirates, as verified by circumference measurements. In addition, tumescent liposuction is unlikely to cause major lesions of epifascial lymph vessels during suction procedures vertical to the extremity axis. Therefore, in this respect, this technique is superior to dry suction.     

Evaluation method of artificial acoustical environment: visualization of sound intensity

Recent development of sound reproduction systems such as 5.1 surround produces artificial sound field inside the enclosure. The acoustic characteristic of the enclosure is an important factor which determines the quality of the sound field reproduction. This paper provides a useful method for evaluating the characteristics of the sound field in the enclosed space. The proposed method is based on the visualization of the measured sound intensity. In this research, the sound intensity is obtained by measuring the impulse responses from the sound source to the receiving points. The direction and the strength of the intensity can be interpreted as having a strong correlation with the reflected sound from the corresponding direction. The proposed method thus projects that information, i.e., the arriving direction and the strength of the intensity, as the circle having appropriate radius onto the surface of the rectangular wire-frame box. This visualization makes it easy to grasp the fundamental characteristics of the reflections in the enclosure.     

Spatial processing within the mustache bat echolocation system: possible mechanisms for optimization

1. The directionality of an echolocation system is determined by the acoustic properties of both the emitter and receiver, i.e., by the radiation pattern of the emitted pulse and the directionally of the external ears. We measured the directionality of the echolocation system of the greater mustache bat (Pteronotus parnellii) at the 30 kHz, 60 kHz and 90 kHz harmonics of its echolocation pulse by summing, at points throughout the frontal sound field, the echo attenuation due to the spread of pulse energy and the attenuation due to the spread of pulse energy and the attenuation due to the directionality of its external ears. The pulse radiation pattern at the 3 harmonics was measured by comparing the output of a microphone moved throughout the frontal sound field against a second reference microphone at the center of the field. External ear directionality at the 3. harmonics was measured by presenting free-field sounds throughout the frontal sound field, and recording the intensity thresholds of cochlear microphonic potentials, and the intensity thresholds of monaural neurons in the inferior colliculus tuned to one of the 3 harmonics. 2. When compared with ear directionality, the echolocation system was found to be more directional for the center of the sound field in several respects. At all harmonics, attenuation of sounds originating in the peripheral part of the field was increased by 10 to 13 dB. Areas of maximum sound intensity contracted toward the center of the field. Also, the isointensity contours of the echolocation system were more radially symmetrical about the center of the field. 3. At 60 kHz, sound intensity along the azimuth within the echolocation system was nearly constant 26 degrees to either side of the center of the field. This suggests that the radiation pattern of the echolocation pulse and the directionality of the external ears complement one another to produce an acoustic environment at the center of the sound field in which stimulus intensity is stabilized to allow more effective analysis of various aspects of the echolocation target. In particular, we suggest that this intensity stabilization may allow the bat to more effectively resolve the interaural intensity differences it uses to localize prey. 4. Predictions of the azimuthal spatial tuning of binaurally sensitive neurons in the inferior colliculus within the echolocation system were compared with their spatial tuning when only ear directionality is considered.(ABSTRACT TRUNCATED AT 400 WORDS)     

Another indication for liposuction: small facial lipomas.

The treatment of facial lipomas at times requires the use of incisions that are less than satisfactory in either size or location. In an effort to minimize scarring, the authors have been removing these lesions with liposuction. The purpose of this study was to review the authors' experience in treating small facial lipomas using liposuction. Over the last 10 years, the authors treated five patients with forehead lipomas by removal with liposuction through hair-bearing scalp incisions. All patients were evaluated after the procedure for bleeding, paresthesias, recurrence, scarring, and overall satisfaction with the procedure. All of these patients had lipomas that measured 4 cm or less at the time of surgery. No patient experienced hematoma, nerve injury, or recurrence. All patients were completely satisfied with their result and scar. The literature describes an advantage to using liposuction for the treatment of medium (4 to 10 cm) and large (>10 cm) lipomas. Because small lipomas (<4 cm) can be extracted through small incisions, the literature reports no advantage to removal with liposuction. However, favorable aesthetic results can be obtained by removing small facial lipomas with liposuction through strategically placed incisions.