Random flap survival with hyperbaric oxygen: daily versus twice-daily treatments.

PURPOSE: Hyperbaric oxygen (HBO2) therapy is used to improve the survival of compromised flaps. Compromised flaps are complications encountered postsurgically, or in traumatic degloving or avulsion injuries. Failed flaps lead to persistence of the defect, requirement of another donor site, and psychosocial sequelae. Although evidence of the benefit of HBO2 therapy is significant, there is no consensus on the optimal treatment regimen. The purpose of this study is to examine whether twice-daily treatments (BID HBO2) provide additional benefit compared to daily treatments (QD HBO2) in a rat compromised random flap model. METHODS: A rat random flap model was used with subjects divided into three groups: 1) control group; 2) QD HBO2; and 3) BID HBO2, where HBO2 was performed with 100% oxygen at 2.5 atmospheres absolute/ATA (253 kPa) for 90 minutes. After 10 days, areas of flap necrosis were measured and biopsies were taken for histologic analysis. Statistical analysis was performed using ANOVA and paired t-tests. A P-value ⟨0.05 was considered significant. RESULT: Both treatment groups had significantly increased mean flap survival compared to controls (P⟨0.05). There was no significant difference in flap survival between the QD and BID groups. Capillary proliferation in the QD group was increased compared with controls. CONCLUSION: Both QD and BID HBO2 protocols can significantly decrease random flap necrosis. However, the results of this study suggest there is no additional benefit gained with BID treatments. Clinical studies are warranted to confirm these findings and assist in formalization of protocols for the use of HBO2in treating compromised random flaps.

Lidocaine-induced ASC apoptosis (tumescent vs. local anesthesia).

BACKGROUND: The purpose for the present study was to determine which anesthetic method, local anesthesia versus tumescent, is superior for liposuction in terms of adipose-derived stem cell (ASC) survival in lipoaspirate; which component, lidocaine versus lidocaine with epinephrine, in anesthetic solutions could affect ASC survival; and which mechanism, necrosis versus apoptosis, is involved in lidocaine-induced ASC death. METHODS: Human lipoaspirates were harvested using standard liposuction technique. Individuals scheduled for liposuction on bilateral body areas gave consent and were included in the study. On one area, liposuction was conducted under local anesthesia with lidocaine/epinephrine. On the contralateral area, liposuction was accomplished with tumescent wetting solution containing lidocaine/epinephrine. Lipoaspirates were processed for the isolation of stromal vascular fraction (SVF). ASC survival was determined by the number of adherent ASCs after 24 h of SVF culture. Lidocaine dose-response (with or without epinephrine) on cultured ASCs was examined. Lidocaine-induced ASC apoptosis and necrosis was determined by Annexin V-FITC/Propidium Iodide (PI) assay and analyzed by flow cytometry. RESULTS: All of the participants were female adults. The average age was 45 ± 4.0 years (±SEM) and the average BMI was 28 ± 1.0 (±SEM). Lipoaspirate samples (n = 14) treated by local anesthesia (n = 7/group) or tumescent anesthesia (n = 7/group) were investigated. Liposuction sites were located in the hip or thigh. The average number of adherent ASCs was 1,057 ± 146 k in the local anesthesia group, which was significantly lower than the 1,571 ± 111 k found in the tumescent group (P = 0.01). ASC survival was significantly lower in the lidocaine group and in a dose-dependent manner as compared to the correspondent PBS controls (P < 0.05 or P < 0.01). ASC survival was significantly lower in both the lidocaine and lidocaine with epinephrine groups when compared to PBS controls. Annexin/PI assay showed that ASC apoptosis (but not necrosis) in the lidocaine group was significantly higher than that in the corresponding PBS control (P = 0.026). CONCLUSIONS: Tumescent anesthesia is the superior method for liposuction with respect to ASC preservation compared to local anesthesia. Lidocaine could cause significant ASC apoptosis.

Evaluation of AlloMax acellular dermal matrix for objective collagen deposition.

Acellular dermal matrix products are popular in various aspects of surgical reconstruction including hernia repairs and breast reconstructions. The goal of this study was to determine quantitative collagen weights of AlloMax (C. R. Bard, Inc. [Davol], Warwick, RI) and of contralateral dermis for composition comparison. A rehydrated sample of AlloMax was subcutaneously implanted on the dorsum of 18 male Wistar rats. Rats were randomly assigned to groups on the basis of in vivo implant time: 1, 3, and 6 weeks. At the end of the implant time, the AlloMax was removed and a section of contralateral dermis was excised as a control. Hydroxyproline, rat Collagen I and Collagen III, and neoangiogenesis were determined in the sections. The results are reported as mean ± standard error of the mean. Analysis of variance was used to evaluate the between-group differences. A p value of 0.05 or less was considered significant. Hydroxyproline was significantly increased in the 6-week AlloMax implant (26.19 ± 1.05 vs. 15.03 ± 3.29). Collagen I and Collagen III were significantly increased following 3 weeks in vivo (612.5% ± 98.0 vs. 312.9% ± 82.7, p < 0.05 Collagen I). Neoangiogenesis was significantly increased at 3 and 6 weeks in vivo (2.3 ± 0.3 and 1.9 ± 0.3). Acellular AlloMax was rapidly incorporated into the rat dorsum. The measurement parameters were greater than or equivalent to contralateral dermis in this study.

The effect of hyperbaric oxygen on nitric oxide synthase activity and expression in ischemia-reperfusion injury.

BACKGROUND: Hyperbaric oxygen (HBO) mitigates ischemia-reperfusion (IR) injury via a nitric oxide mechanism that is nitric oxide synthase (NOS) dependent. The purpose of this study was to investigate this NOS-dependent mechanism by examining isoform-specific, tissue-specific, and time-specific upregulation of NOS mRNA, protein, and enzymatic activity. METHODS: We raised a gracilis flap in Wistar rats that were separated into early and late phases. Treatment groups included nonischemic control, IR, HBO-treated ischemia-reperfusion (IR-HBO), and nonischemic HBO control. We harvested tissue-specific samples from gracilis, rectus femoris, aorta, and pulmonary tissues and processed them by reverse transcription polymerase chain reaction and Western blot to determine upregulation of isoform-specific NOS mRNA and protein. We also harvested tissue for NOS activity to investigate upregulation of enzymatic activity. Data are presented as mean ± standard error of the mean with statistics performed by analysis of variance. P ≤ 0.05 was considered significant. RESULTS: There was no increase in NOS mRNA in the early phase. In the late phase, there was a significant increase in endothelial-derived NOS (eNOS) mRNA in IR-HBO compared with IR in gracilis muscle (79.4 ± 22.3 versus 36.1 ± 4.5; P < 0.05) and pulmonary tissues (91.0 ± 31.2 versus 30.2 ± 3.1; P < 0.01). There was a significant increase in the late-phase eNOS pulmonary protein IR-HBO group compared with IR (235.5 ± 46.8 versus 125.2 ± 14.7; P < 0.05). Early-phase NOS activity was significantly increased in IR-HBO compared with IR in pulmonary tissue only (0.049 ± 0.009 versus 0.023 ± 0.003; P < 0.05). CONCLUSIONS: The NOS-dependent effects of HBO on IR injury may result from a systemic effect involving an early increase in eNOS enzymatic activity followed by a late-phase increase in eNOS protein expression within the pulmonary tissues.

Pneumomediastinum following hyperbaric oxygen therapy for carbon monoxide poisoning: case report.

A 5-year-old boy trapped in a house fire was transported to the emergency department, unconscious with suspected carbon monoxide poisoning. The patient underwent a difficult intubation, but did not initially demonstrate any radiographic abnormalities. The patient remained intubated and underwent hyperbaric oxygen therapy using the carbon monoxide treatment protocol. Immediate post-therapy chest radiograph revealed the development of occult pneumomediastinum. The patient remained stable on positive-pressure ventilation and the pneumomediastinum resolved spontaneously. The patient was extubated on post-injury Day #2 and was discharged post-injury Day #4 with no residual clinical sequelae. The development of pneumomediastinum associated with hyperbaric oxygen therapy for carbon monoxide poisoning appears to be a rare phenomenon. However, clinicians should be aware of the risk factors that predispose patients to developing pneumomediastinum and have a low threshold for obtaining routine pre- and post-procedure screening chest radiographs in intubated and critically ill patients, particularly in children.

The effect of lipoaspirates cryopreservation on adipose-derived stem cells.

BACKGROUND: Autologous fat grafting has gained popularity, particularly with the discovery of adipose-derived stem cells (ADSC). The possibility of freezing lipoaspirates (LA) for later use has intriguing clinical potential. However, the effect of LA cryopreservation on ADSC is unclear. OBJECTIVES: The authors explore the effect of LA cryopreservation on ADSC viability. METHODS: Human LA (n = 8) were harvested using a standard technique. Lipoaspirate samples were either processed immediately as fresh LA (A) or stored at -20°C and then at -80°C for 30 days with (B) or without (C) freezing medium. Stromal vascular fraction (SVF) was separated from adipocytes and either cultured to obtain purified ADSC or processed for the isolation of 3 distinct ADSC subpopulations (CD90(+)/CD45(-), CD105(+)/CD45(-), and CD34(+)/CD31(-)). Apoptosis and necrosis were determined by an annexin V/propidium iodide assay and quantified by flow cytometry. The capability of ADSC for long-term proliferation and differentiation was also examined. RESULTS: There were no significant differences in the apoptosis and necrosis of adipocytes, SVF, or ADSC between groups A and B. However, cell viability in SVF and ADSC was significantly compromised in group C as compared with group B (P < .01) due to higher ADSC apoptosis but not necrosis. The viable ADSC isolated from fresh or frozen LA were cultured for more than 20 passages and demonstrated similar patterns and speed of proliferation with strong capability to differentiate, evidenced by cell doubling time and positive staining with Oil Red O (Sigma-Aldrich, St Louis, Missouri) and alkaline phosphatase. CONCLUSIONS: Lipoaspirates cryopreservation had a significant impact on ADSC apoptosis but not on ADSC necrosis, proliferation, or differentiations. Freezing medium provides significant protection against ADSC apoptosis.

Contributing variables to post mastectomy tissue expander infection.

Tissue expander breast reconstruction is a common post mastectomy breast procedure performed by plastic surgeons. The purpose of this study was to define the incidence of breast reconstruction prosthetic infection, relate patient characteristics with increased rate of infection, and analyze the influence of postoperative complications to expander/implant infection. A retrospective, single-institution chart review of 195 women with post mastectomy tissue expander/implant reconstructions performed from 2006 through 2008 was conducted. Total periprosthetic infection rate was calculated. Patient factors, operative technique, and noninfectious complications were analyzed and related to increased periprosthetic infection rate. A binary logistic regression model was fitted using periprosthetic infection as the dependent variable and 12 patient characteristics as independent variables, followed by a step-wise model for best fit with a limited number of independent variables. The overall periprosthetic infection rate per patient over the 2 year period was 5.1%. The incidence of periprosthetic infection per reconstructed breast was 3.2%. Odds ratio estimates indicated that the presence of cellulitis increased the odds of periprosthetic infection more than 200 times (p = <0.0001), and inpatient procedures increased the odds 16 times (p = 0.02). Other variables (i.e., age > 65, DM, flap necrosis, smoking, dehiscence, AlloDerm, etc) failed to reach statistical significance (p > 0.05). Postoperative breast cellulitis and inpatient status appear to be significant risk factors for increased periprosthetic infection. No significant increase in periprosthetic infection rate was noted with other variables in this model.

The effect of hyperbaric oxygen on compromised grafts and flaps.

The use of grafts and flaps serves as an integral tool in the armamentarium of the reconstructive surgeon. Proper planning and surgical judgment are critical in the ultimate success of these procedures. However, there are situations when grafts and/or flaps can become compromised and require urgent intervention for salvage. These instances can include irradiated or otherwise hypoxic wound beds, excessively large harvested grafts, random flap ischemia, venous or arterial insufficiency and ischemia-reperfusion injury. Alternatively, compromised grafts and flaps can be inadvertently created secondary to trauma. It is in these types of cases that hyperbaric oxygen therapy (HBO2T) can serve as a useful adjunct in the salvage of compromised flaps and grafts. This review outlines the extensive basic science and clinical evidence available in support of the use of HBO2T for compromised grafts and flaps. The literature demonstrates the benefit of adjunctive HBO2T for multiple types of grafts and flaps with various etiologies of compromise. HBO2T can enhance graft and flap survival by several methods including decreasing the hypoxic insult, enhancing fibroblast function and collagen synthesis, stimulating angiogenesis and inhibiting ischemia-reperfusion injury. The expedient initiation of hyperbaric oxygen therapy as soon as flap or graft compromise is identified maximizes tissue viability and ultimately graft/flap salvage.

Objective evaluation of skill acquisition in novice microsurgeons.

INTRODUCTION: Medical training is increasingly focused on patient safety, limiting the ability to practice technical skills in the operative arena. Alternative methods of training residents must be designed and implemented. METHODS: Three expert microsurgeons were solicited to develop two drills to help residents acquire the basic subset of skills in microsurgery. The first drill was performance of five consecutive simple interrupted sutures on a rubber glove. Expert proficiency was considered a drill time of two standard deviations from expert mean. The drill was performed up to 10 times until completion of the task at expert proficiency. The second drill was performance of an anastomosis on silastic tubing. Residents performed the drill sequentially until performing two consecutive drills at expert proficiency. RESULTS: Eight residents with no microsurgical experience volunteered. Six of the eight residents were able to perform the rubber glove drill at expert proficiency within 10 attempts, with an average of 5.3. All of the residents were able to perform two consecutive silastic tubing drills at expert proficiency within nine attempts, with an average of 5.4. CONCLUSION: Residents were able to acquire a basic subset of microsurgical skills within a reasonable time period using these drills.

Therapeutic interventions against reperfusion injury in skeletal muscle.

Ischemia/reperfusion (I/R) injury in the skeletal muscle is inevitable in many vascular and musculoskeletal traumas, diseases, free tissue transfers, and during time-consuming reconstructive and transplantation surgeries. Although skeletal muscle has a higher tolerance to ischemia than other organs, prolonged ischemia can still result in significant complications, including muscle necrosis and apoptosis. One of the major goals in the treatment of ischemia is early restoration of blood flow (reperfusion) to the area at risk. However, reperfusion has led to a new pathophysiologic condition called "reperfusion injury," a phenomenon which actually provokes a distinct degree of tissue injury. The purpose of this review is to examine the current state of understanding of I/R injury as well as to highlight recent developments on I/R interventions including our own experience in this particular field. We expect, as our acquired experience and the increased knowledge of underlying mechanisms of I/R injury, more effective interventions aimed to reduce I/R injury will be developed to interfere with or modulate this particular pathophysiologic processes.

Melatonin attenuates I/R-induced mitochondrial dysfunction in skeletal muscle.

BACKGROUND: Our recent studies have shown that ischemia/reperfusion (I/R) produces significant necrosis and apoptosis in the cells of skeletal muscle. Our previous studies also demonstrated that melatonin provides significant protection against superoxide generation, endothelial dysfunction, and cell death in the skeletal muscle after I/R. Mitochondria are essential for cell survival, because of their roles as ATP producers as well as regulators of cell death. However, the efficacy of melatonin on I/R-induced mitochondrial dysfunction in the skeletal muscle in vivo has not been demonstrated in the literature. MATERIALS AND METHODS: Vascular pedicle isolated rat gracilis muscle model was used. After 4 h of ischemia followed by 24 h of reperfusion, gracilis muscle was harvested, and mitochondrial as well as cytosolic fractions were isolated. Mitochondrial dysfunction was determined by the alteration of mitochondrial membrane potential and the release of the proapoptotic protein, cytochrome c. Three groups were designed; sham I/R, I/R-V (I/R with vehicle), and I/R-Mel (I/R with melatonin). Melatonin or vehicle was given intravenously 10 min prior to reperfusion and 10 min after reperfusion. RESULTS: We found that the capability of uptake of fluorescent JC-1 dye in skeletal muscle cells was substantially improved in I/R-Mel group compared with I/R-V group. Melatonin significantly inhibited the outflow of cytochrome c from mitochondria to cytoplasm, which was demonstrated in the I/R-V group. CONCLUSIONS: Melatonin significantly attenuates I/R-induced mitochondrial dysfunction, such as the depolarization of mitochondrial membrane potential and the release of the proapoptotic protein, cytochrome c, from the mitochondria.

Distraction osteogenesis of the palate: an experimental model.

Although most cleft palates can be closed with conventional mucoperiosteal flap techniques, the occasional wide cleft or difficult fistula has few options for an early 1-stage reconstruction. Distraction osteogenesis (DO) has the potential to close the palate with both hard and soft tissues as well as mitigating the possibility of future oronasal fistula. A right unilateral 5-mm cleft was surgically created in 15 New Zealand white rabbits. In group 1 (N = 5), no further repair was performed (NR); in group 2 (N = 5), mucoperiosteal flaps were used to close the cleft for a soft-tissue-only repair (STR); in group 3 (N = 5), a unilateral osteotomy in the palate on the noncleft side allowed distraction of the palatal shelf across the cleft until closed (DO). Clinical examination, Micro-computed tomography bone density, direct cephalometry, and histology were evaluated at 8 weeks after the completion of distraction. Bone mineral density (BMD; mg/mL) data were obtained from micro-computed tomography scans of both the cleft and noncleft sides for each rabbit, and a ratio was obtained [(BMDc/BMDnc) x100]; NR = 1.38, STR = 44.27, DO = 88.36, P = 0.007. Facial measurements revealed no growth disturbances as a result of DO. Histologic evaluation revealed increased organization of new bone in DO group compared with NR and STR. Clinically, DO group rabbits did not show any increase in feeding disturbances, infection, or wound healing. The success of membranous facial bone distraction has been applied to a new model for palatal repair with the potential to ameliorate the problems associated with soft-tissue-only repair.

Reperfusion-induced neutrophil CD18 polarization: effect of hyperbaric oxygen.

BACKGROUND: Hyperbaric oxygen (HBO) inhibits ischemia reperfusion (IR) -induced neutrophil adhesion to endothelium through an unknown mechanism. This study evaluates the effect of HBO on IR-stimulated neutrophil adhesion and polarization of expressed CD18 adhesion molecules using a novel in vitro adhesion assay and confocal microscopy. MATERIALS AND METHODS: Neutrophils from normal animals were isolated from whole blood and incubated with plasma from rat gracilis muscle flaps on coverslips pretreated with ICAM. Percent adherence to ICAM and CD18 polarization was evaluated in the following five groups: (1) Nonischemic control, n = 15; (2) 4 h ischemia (IR, n = 15); (3) 4 h ischemia with HBO treatment (100% oxygen at 2.5 atmospheres absolute (IR + HBO, n = 15)); (4) 4 h ischemia with 100% oxygen at room temperature and pressure (RTP) (IR + normobaric hyperoxia, n = 5); and (5) 4 h ischemia with 8% oxygen at 2.5 atmospheres absolute (IR + hyperbaric normoxia, n = 5). Direct HBO treatment of neutrophils was also evaluated. RESULTS: Neutrophils exposed to IR plasma showed a significant increase in percent adherent (0.8 +/- 0.1% versus 16.7 +/- 2.2%, P < 0.05) and polarized cells (6.2 +/- 1.7% versus 43.9 +/- 12.2%, P < 0.05) compared to controls. Hyperbaric oxygen significantly reduced the adhesion and polarization to 1.6 +/- 0.3 and 4.1 +/- 2.5%, respectively (P = < 0.05). Normobaric hyperoxia and hyperbaric normoxia did not affect neutrophil adherence or CD18 polarization following IR. Direct HBO treatment of neutrophils did not change the percent of polarized cells in IR. CONCLUSIONS: Hyperbaric oxygen inhibits IR-induced neutrophil adhesion by blocking CD18 surface polarization and requires plasma exposure to HBO. Treatment with oxygen or pressure alone is not effective.

Basal cell carcinoma and rhinophyma.

Rhinophyma, the end stage in the development of acne rosacea, is characterized by sebaceous hyperplasia, fibrosis, follicular plugging, and telangiectasia. Although it is commonly considered a cosmetic problem, it can result in gross distortion of soft tissue and airway obstruction. Basal cell carcinoma (BCC) is a rare finding in patients with rhinophyma. The objective of this study is to review the literature of BCC in rhinophyma and report on a case. A 70-year-old male presented with long-standing rosacea that resulted in a gross nasal deformity. The patient suffered from chronic drainage and recurrent infections that failed conservative treatment with oral and topical antibiotics. The patient decided to proceed with surgical intervention and underwent tangential excision and dermabrasion in the operating room. Since 1955 there have been 11 cases reported in the literature. In our case, the pathology report noted that the specimen had an incidental finding of a completely resected BCC. The patient did well postoperatively and at follow-up remains tumor-free. Despite the uncommon occurrence of BCC in resection specimens for rhinophyma, we recommend that all specimens be reviewed by a pathologist. If BCC is detected, re-excision may be necessary and careful follow-up is mandatory. Larger studies would be needed to determine the correlation between the 2 conditions.

Nocardial septic arthritis of the wrist diagnosed and treated by arthroscopy.

This is the first case of Nocardial septic arthritis of the wrist that has been reported without any cutaneous presentation. It was successfully diagnosed and treated with wrist arthroscopy. Arthroscopy is less traumatic and done through smaller incisions than the traditional open technique.

Acute pavement burns: a unique subset of burn injuries: a five-year review of resource use and cost impact.

This study focuses on the hospital care of a rare subset of burn injuries caused by contact with environmentally heated pavement, to further understand the required use of resources. This article aims to show that pavement burns are typically more severe than their flame/scald counterparts. A retrospective review of patients admitted to the burn center with injuries suffered from contact with hot pavement was performed. Patients were stratified on the presence or absence of altered mental status (AMS) and additional inciting factors. A representative sample of similarly sized flame and scald wounds treated in the same time period was compiled for comparison. Those with pavement burns had a significantly greater requirement for operative intervention, repetitive debridements, overall cost/percent burned, and lengthier hospital stays than those with flame/scald burns. Pavement burn victims with AMS were significantly more likely to require an operation, a greater cost/percent burned, and longer hospital stays than those without AMS. Pavement burns are significantly worse than similarly sized scald/flame burns with regards to length of stay and total hospital costs, and the necessity of initial and repetitive operative intervention. These discrepancies are even greater in patients with AMS as a concomitant inciting factor. It is apparent that these wounds often continue to deepen during a patient's stay, likely because of continued pressure on the wounds while recumbent. As such, this article highly recommends pressure off-loading beds and more aggressive debridement in the treatment of these unique injuries.

Elimination of reperfusion-induced microcirculatory alterations in vivo by adipose-derived stem cell supernatant without adipose-derived stem cells.

BACKGROUND: In the present study, the authors hypothesized that adipose-derived stem cells in cell culture may secrete multiple cytokines in the supernatant, which might have a significant impact in vivo on the reperfusion-induced microcirculatory alterations and endothelial dysfunction. METHODS: Fat tissue was surgically harvested from rat flanks and processed for adipose-derived stem cell isolation; cells (1 × 10(6)) were subcultured for 3, 6, 9, and 12 days without passage. The postcultivated medium was harvested with medium change every 3 days. After centrifugation, the supernatant was collected and stored at -20°C. Supernatant collected on day 9 was analyzed for eight oxidative stress cytokines by an enzyme-linked immunosorbent assay strip. The effect of the supernatant on the reperfusion-induced microcirculatory alterations was examined in the vascular pedicle of isolated rat cremaster muscles subjected to 4 hours of ischemia followed by 2 hours of reperfusion. RESULTS: Enzyme-linked immunosorbent assay results demonstrated that adipose-derived stem cells produced several highly expressed cytokines in the supernatant. The average concentration of interleukin-6, in particular, was 5-fold higher compared with control. The reperfusion-induced vasospasm, arteriole stagnation, and the capillary no-reflow that often appear in the early phase of reperfusion were eliminated by adipose-derived stem cell supernatant. CONCLUSIONS: Adipose-derived stem cells in cell culture display cytokine secretory properties that enable the cells to act through paracrine signaling. The supernatant even without cells could be used as a paracrine agent to interfere with the reperfusion-induced microcirculatory alterations and endothelial dysfunction.

Hyperbaric oxygen and wound healing.

Problem wounds, which fail to respond to traditional medical and surgical therapy, can be challenging to the plastic surgeon. Surgical, outpatient, and inpatient wound care costs can be exorbitant. Indirect costs, such as those related to patient productivity, disability, and premature death, can also be significant. The underlying problem in failure of a wound to heal is usually hypoxia and infection. HBO treatments in selected patients can facilitate healing by increasing tissue oxygen tension, thus providing the wound with a more favorable environment for repair. Therefore, HBO therapy can be an important component to any comprehensive wound care program.

Effect of L-arginine on leukocyte adhesion in ischemia-reperfusion injury.

Nitric oxide has been reported to be beneficial in preserving muscle viability following ischemia-reperfusion injury. The purpose of this study was to evaluate the influence of nitric oxide via L-arginine on leukocyte adhesion following ischemia-reperfusion injury. Intravital videomicroscopy of rat gracilis muscle was used to quantify changes in leukocyte adherence. The gracilis muscle was raised on its vascular pedicle in 48 male Wistar rats. The animals were assigned to one of five groups: (1) nonischemic control; (2) ischemia-reperfusion; (3) ischemia-reperfusion and L-arginine; (4) ischemia-reperfusion and Nomega-nitro-L-arginine methyl ester (L-NAME); and (5) ischemia-reperfusion, L-NAME, and L-arginine. All groups that included ischemia-reperfusion were subjected to 4 hours of global ischemia followed by 2 hours of reperfusion. L-Arginine (10 mg/kg) and L-NAME (10 mg/kg) were infused into the contralateral femoral vein beginning 5 minutes before reperfusion, for a total of 30 minutes. The number of adherent leukocytes was counted at baseline and at 5, 15, 30, 60, and 120 minutes after reperfusion (reported as mean change from baseline, +/- SEM). Groups were compared by repeated-measures analysis of variance (five groups, five times). P < or =0.05 was accepted as significant. L-Arginine significantly reduced leukocyte adherence to venular endothelium during reperfusion when compared with the ischemia-reperfusion group (1.39 +/- 0.92 versus 12.78 +/- 1.43 at 2 hours, p < 0.05). Administration of L-NAME with L-arginine showed no significant difference in adherent leukocytes when compared with the ischemia-reperfusion group (10.28 +/- 2.03 at 2 hours). The nitric oxide substrate L-arginine appears to reduce the deleterious neutrophil-endothelial adhesion associated with ischemia-reperfusion injury. L-NAME (nitric oxide synthesis inhibitor) given concomitantly with L-arginine reversed the beneficial effect of L-arginine alone, indicating that L-arginine may be acting via a nitric oxide synthase pathway. These results suggest an important role for nitric oxide in decreasing the neutrophil-endothelial interaction associated with ischemia-reperfusion injury.

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.