Monopolar stray energy in robotic surgery.

INTRODUCTION: Stray energy transfer from monopolar radiofrequency energy during laparoscopy can be potentially catastrophic. Robotic surgery is increasing in popularity; however, the risk of stray energy transfer during robotic surgery is unknown. The purpose of this study was to (1) quantify stray energy transfer using robotic instrumentation, (2) determine strategies to minimize the transfer of energy, and (3) compare robotic stray energy transfer to laparoscopy. METHODS: In a laparoscopic trainer, a monopolar instrument (L-hook) was activated with DaVinci Si (Intuitive, Sunnyvale, CA) robotic instruments. A camera and assistant grasper were inserted to mimic a minimally invasive cholecystectomy. During activation of the L-hook, the non-electric tips of the camera and grasper were placed adjacent to simulated tissue (saline-soaked sponge). The primary outcome was change in temperature from baseline (°C) measured nearest the tip of the non-electric instrument. RESULTS: Simulated tissue nearest the robotic grasper increased an average of 18.3 ± 5.8 °C; p < 0.001 from baseline. Tissue nearest the robotic camera tip increased (9.0 ± 2.1 °C; p < 0.001). Decreasing the power from 30 to 15 W (18.3 ± 5.8 vs. 2.6 ± 2.7 °C, p < 0.001) or using low-voltage cut mode (18.3 ± 5.8 vs. 3.1 ± 2.1 °C, p < 0.001) reduced stray energy transfer to the robotic grasper. Desiccating tissue, in contrast to open air activation, also significantly reduced stray energy transfer for the grasper (18.3 ± 5.8 vs. 0.15 ± 0.21 °C, p < 0.001) and camera (9.0 ± 2.1 vs. 0.24 ± 0.34 °C, p < 0.001). CONCLUSIONS: Stray energy transfer occurs during robotic surgery. The assistant grasper carries the highest risk for thermal injury. Similar to laparoscopy, stray energy transfer can be reduced by lowering the power setting, utilizing a low-voltage cut mode instead of coagulation mode and avoiding open air activation. These practical findings can aid surgeons performing robotic surgery to reduce injuries from stray energy.

Blood vessel occlusion in peri-burn tissue is secondary to erythrocyte aggregation and mitigated by a fibronectin-derived peptide that limits burn injury progression.

Although vascular occlusion has long been noted in peri-burn tissue, the literature is inconsistent regarding the nature of the occlusion, with articles in the 1940s claiming that erythrocytes were the culprit and in the 1980s-1990s that microthrombi were responsible. To better define the nature of vessel occlusion, we studied two porcine burn models, a hot comb horizontal injury model and a vertical injury progression model. In both cases, tissue from the first two days after burn were stained with hemotoxylin and eosin, or probed for platelets or for fibrinogen/fibrin. Erythrocytes, identified as nonstained, clumped, anuclear, 5 µm cells, occluded most blood vessels (BVs) in both burn models. In contrast, platelet or fibrinogen/fibrin antibodies stained BV occlusions minimally at early time points, and only up to 16% of deep dermal BVs at 48 hours in the hot comb model and up to 7% at 24 hours in the vertical injury progression model. Treatment of animals with a fibronectin-derived peptide (P12), which limits burn injury progression and can dilate peripheral microvasculature, reduced erythrocyte occlusion by at least 50%, speeded healing and reduced scarring. Early erythrocyte aggregation, rather than thrombosis, explains the ineffectiveness of anticoagulants to prevent burn injury progression.

Laparoscopic sleeve gastrectomy: long-term weight loss outcomes.

BACKGROUND: Laparoscopic sleeve gastrectomy (LSG) has become an increasingly popular stand-alone weight loss surgery, but there is a paucity of long-term efficacy data. OBJECTIVE: To determine long-term outcomes for patients undergoing LSG. SETTING: Tertiary care university hospital in the United States. METHODS: This study presents a case series of the first 16 patients undergoing LSG at our institution. Inclusion criteria were accepted indications for bariatric surgery, and exclusion criteria were any prior bariatric surgery, gastrectomy, substance abuse, uncontrolled psychiatric illness, end-stage organ disease, or advanced-stage cancer. Patients were followed for 7 years. Outcomes included percent excess weight loss (%EWL), percent weight loss (%WL), resolution of co-morbidities, and major and minor complications. RESULTS: Patients enrolled in this study had a mean body mass index (BMI) of 43.5 kg/m(2) and a mean age of 49, and 14 of 16 patients were women. Fourteen of 16 patients had 7-year follow-ups with a mean %WL of 29.6%±8.95 and a mean %EWL of 59.6%±89.9%. At 7 years, 11 of 14 patients achieved>50% EWL. One-year follow-up data revealed a mean EWL of 72%±20%, which was significantly greater than the %EWL at 7 years (P = .005). Complications included 1 partial obstruction at the gastric incisura angularis and 1 subacute leak; both were managed endoscopically. There were no reoperations and no deaths. Five of 14 patients experienced new-onset gastroesophageal reflux disease. CONCLUSIONS: At 7 years postoperative, the LSG remained a durable and successful operation.

Endothelial necrosis at 1 hour postburn predicts progression of tissue injury.

Burn injury progression has not been well characterized at the cellular level. To define burn injury progression in terms of cell death, histopathologic spatiotemporal relationships of cellular necrosis and apoptosis were investigated in a validated porcine model of vertical burn injury progression. Cell necrosis was identified by high mobility group box 1 protein and apoptosis by Caspase 3a staining of tissue samples taken 1 hour, 24 hours, and 7 days postburn. Level of endothelial cell necrosis at 1 hour was predictive of level of apoptosis at 24 hours (Pearson's r = 0.87) and of level of tissue necrosis at 7 days (Pearson's r = 0.87). Furthermore, endothelial cell necrosis was deeper than interstitial cell necrosis at 1 hour (p < 0.001). Endothelial cell necrosis at 1 hour divided the zone of injury progression (Jackson's zone of stasis) into an upper subzone with necrotic endothelial cells and initially viable adnexal and interstitial cells at 1 hour that progressed to necrosis by 24 hours and a lower zone with initially viable endothelial cells at 1 hour but necrosis and apoptosis of all cell types by 24 hours. Importantly, this spatiotemporal series of events and rapid progression resembles myocardial infarction and stroke and implicates mechanisms of these injuries, ischemia, ischemia reperfusion, and programmed cell death in burn progression.

Histopathologic staining of low temperature cutaneous burns: comparing biomarkers of epithelial and vascular injury reveals utility of HMGB1 and hematoxylin phloxine saffron.

Histopathology remains the gold standard for evaluation of burn depth, progression, and healing, but burn literature offers little guidance on the best stains for analysis of these complex and evolving injuries. A battery of histochemical and immunohistochemical stains was compared on adjacent sections to determine the best stains for histopathologic study and imaging of burns. Using a validated porcine model of vertical burn progression, full-thickness cutaneous biopsies were stained using hematoxylin and eosin, Hematoxylin phloxine saffron (HPS), Masson Trichrome, Elastin Von Gieson, Movatt's Pentachrome, vimentin, CD31, KI-67, caspase 3a, and high mobility group box 1. Depth of collagen degeneration, cellular necrosis, apoptosis, and vascular occlusion; and reparative processes of cellular hyperplasia, reepithelialization, and new collagen deposition were measured by ocular microscopy. High mobility group box 1 was superior for necrosis between 1 and 24 hours postburn. Vimentin underestimated necrosis until 48 hours postburn. For overall assessment, hematoxylin and eosin and HPS were comparable, except for analysis of thermally injured collagen, vessel occlusion, erythrocyte extravasation, and polariscopic study of collagen deposition, where HPS was superior. HPS stain offers specific advantages in histopathologic burn analysis. Inexpensive and rapid to produce, HPS allows users to analyze eosinophilic components more precisely than standard hematoxylin and eosin.

Lack of agreement between gross visual and histological assessment of burn reepithelialization in a porcine burn model.

One of the most important and earliest measures of burn healing is wound reepithelialization. Reepithelialization is a vital determinant of wound infection and scarring. Reepithelialization is generally based on gross visual assessment; however, histological assessment remains the criterion standard. We hypothesized that there would be poor agreement (r < .4) between gross visual and histological assessments of burn reepithelialization in a porcine model. The study design was prospective observational using three anesthetized female pigs (20-25 kg). Forty-eight 2.5- × 2.5-cm burns were created on the flanks of pig's using an aluminum bar (150 g) preheated to 80°C for 20 seconds. Burns were treated with an occlusive or antimicrobial dressing and photographed at day 10 for determination of gross percentage reepithelialization in a 1-cm diameter circle in the center of the burn by two experienced clinicians masked to each other's measurements. A 10-mm full-thickness punch biopsy was taken from the center of the burns and evaluated by a board-certified dermatopathologist masked to clinical assessments. One clinician and the dermatopathologist repeated the assessments 1 month apart. The outcome was percentage wound reepithelialization at 10 days. The criterion standard was the histological assessment. Intraobserver and interobserver agreements were calculated with Pearson's correlation coefficients. A coefficient less than .4 was considered poor. Sixteen burns were created on each of three animals. Six wounds were excluded because of the presence of a thick eschar covering the burn, making the gross determination of reepithelialization impossible. Intraobserver agreement for histological reepithelialization was 0.96 (P < .001). Intraobserver agreement for gross visual assessment of reepithelialization was 0.75 (P < .001). Interobserver agreement for gross visual assessment of reepithelialization was 0.60 (P < .001). The agreement between gross visual and histological assessment of burn reepithelialization was -0.25. Although there was a good interobserver agreement for gross visual assessments, there was a poor agreement between gross visual and histological assessments of burn reepithelialization. Care should be used when determining burn reepithelialization based on gross visual assessments alone.

Validation of a vertical progression porcine burn model.

A major potential goal of burn therapy is to limit progression of partial- to full-thickness burns. To better test therapies, the authors developed and validated a vertical progression porcine burn model in which partial-thickness burns treated with an occlusive dressing convert to full-thickness burns that heal with scarring and wound contraction. Forty contact burns were created on the backs and flanks of two young swine using a 150 g aluminum bar preheated to 70°C, 80°C, or 90°C for 20 or 30 seconds. The necrotic epidermis was removed and the burns were covered with a polyurethane occlusive dressing. Burns were photographed at 1, 24, and 48 hours as well as at 7, 14, 21, and 28 days postinjury. Full-thickness biopsies were obtained at 1, 4, 24, and 48 hours as well as at 7 and 28 days. The primary outcomes were presence of deep contracted scars and wound area 28 days after injury. Secondary outcomes were depth of injury, reepithelialization, and depth of scars. Data were compared across burn conditions using analysis of variance and χ(2) tests. Eight replicate burns were created with the aluminum bar using the following temperature/contact-time combinations: 70/20, 70/30, 80/20, 80/30, and 90/20. The percentage of burns healing with contracted scars were 70/20, 0%; 70/30, 25%; 80/20, 50%; 80/30, 75%; and 90/20, 100% (P = .05). Wound areas at 28 days by injury conditions were 70/20, 8.1 cm(2); 70/30, 7.8 cm(2); 80/20, 6.6 cm(2); 80/30, 4.9 cm(2); and 90/20, 4.8 cm(2) (P = .007). Depth of injury judged by depth of endothelial damage for the 80/20 and 80/30 burns at 1 hour was 36% and 60% of the dermal thickness, respectively. The depth of injury to the endothelial cells 1 hour after injury was inversely correlated with the degree of scar area (Pearson's correlation r = -.71, P < .001). Exposure of porcine skin to an aluminum bar preheated to 80°C for 20 or 30 seconds results initially in a partial-thickness burn that when treated with an occlusive dressing progresses to a full-thickness injury and heals with significant scarring and wound contracture.