Tumor Ablation Using 3-Dimensional Electromagnetic-Guided Ultrasound Versus Standard Ultrasound in a Porcine Model.

Introduction. The objective of this study was to compare the placement of ablation needles using 3-dimensional electromagnetic-guided ultrasound (guided) to standard ultrasound guidance (standard) in both laparoscopic surgery and open surgery. Endpoints for this study included targeting accuracy and number of required needle withdrawals and reorientations. Methods. Using a porcine model, fiducial markers were placed into the kidney and liver to represent tumors. Navigation and identification of target sites was achieved using standard or guided ultrasound. Intraprocedural observations as well as the number of needle placement attempts per target were recorded. Three board-certified general surgeons performed the navigation and ablation procedures. After completion of the navigation and ablation procedures, necropsy was performed. The position of the ablation zones relative to the fiducial markers was recorded. Results. A total of 48 procedures were performed across 6 animals (50% open and 50% laparoscopic). Overall, the guided ablations required 50% fewer attempts to successfully target the marker (P = .01). There was a 62% reduction of attempts for guided laparoscopic ablation (P = .006). On subgroup analysis of laparoscopic ablation, the benefit remained for liver (P = .041) ablations, but not for renal ablations (P = .093). There was no significant difference between the groups with regard to targeting accuracy (91.3% guided vs 95.4% standard, P = .58). Conclusions. The number of targeting attempts required during laparoscopic ablation procedures was significantly less with guided than with standard ultrasound, particularly for laparoscopic ablation of liver lesions. These findings suggest that the guided ultrasound can potentially reduce complications during laparoscopic ablation procedures.

High power microwave ablation of normal swine lung: impact of duration of energy delivery on adverse event and heat sink effects.

PURPOSE: The purpose of this study is to assess the impact of duration of energy delivery on adverse events (AEs) and heat sink effects during high power microwave ablation (MWA) of normal swine lung. MATERIALS AND METHODS: High power (100 W) MWA was performed with short (2 min, 18 ablations) or long (10 min, nine ablations) duration of energy delivery in unilateral lung of swine (n = 10). CT imaging was done prior to sacrifice at 2 or 28 d post-treatment, with additional imaging at 7 and 14 d for the latter cohort. Ablation zones were assessed with CT imaging and histopathology analysis. Differences in AEs and ablation characteristics between groups were compared with Fisher's exact test and Student's t-test, respectively. RESULTS: There were no significant differences in formation of air-filled needle tract, cavitation, and pneumonia (p > 0.5) between the treatment groups. Intra-procedural pneumothorax requiring chest tube placement occurred in three animals. Substantial (>20%, p = 0.01) intra-procedural ablation zone distortion was observed in both groups. The presence of large airways or blood vessels did not result in heat sink effect within the ablation zones and was not indicative of reduced ablation size. Increased energy delivery yielded larger (8.9 ± 3.1 cm3 vs. 3.4 ± 1.7 cm3, p < 0.001) spherical ablations (sphericity: 0.70 ± 0.10 vs. 0.56 ± 0.13, p = 0.01). CONCLUSIONS: High power MWA of normal lung with longer duration of energy delivery can create larger spherical ablations, without significant differences in post-procedure AEs when compared with shorter energy delivery time.

A Novel Hemostatic Patch That Stops Bleeding in Cardiovascular and Peripheral Vascular Procedures.

BACKGROUND: Achieving hemostasis during surgery is a common challenge across surgical specialties and procedures, including cardiovascular and peripheral vascular procedures. Although several hemostatic agents are available, they all become less effective as bleeding becomes more vigorous. Veriset™ hemostatic patch is a topical hemostatic agent that has been approved for use on solid organs and in soft tissue. The primary aim of these studies was to assess the safety of Veriset hemostatic patch during cardiovascular and peripheral vascular procedures. METHODS: Adult domestic swine were given intraoperative anticoagulation and systemic antiplatelet therapy, and then underwent a variety of cardiovascular coronary artery bypass graft (CABG anastomosis and aortotomy closure) and peripheral vascular (carotid arteriotomy with patch angioplasty) procedures. Bleeding was identified or created from each anastomotic site and was brisk in many cases. Veriset hemostatic patch, Surgicel(®) Nu-Knit(®) absorbable hemostat, or standard of care treatment was applied topically to the site of bleeding, and time to hemostasis was monitored for each animal. Animals were assessed during and after the surgical procedure to determine the effects of treatment on vessel diameter, clinical laboratory parameters, and host tissue response and/or tissue integration. RESULTS: Application of Veriset hemostatic patch had no effect on vessel diameter, similar to Surgicel Nu-Knit absorbable hemostat and standard of care treatment. Approximately 28 days after application, Veriset hemostatic patch and Surgicel Nu-Knit absorbable hemostat were completely absorbed, with no impact on serum chemistry profiles. Furthermore, Veriset hemostatic patch was as effective or more effective than Surgicel Nu-Knit absorbable hemostat when applied during carotid arteriotomy (30.0 ± 0.0 sec vs. 163.6 ± 86.9 sec, P < 0.001) and CABG anastomosis (91.9 ± 66.0 sec vs. 207.5 ± 159.2 sec, P = 0.053). CONCLUSIONS: Veriset hemostatic patch exhibits similar safety as Surgicel Nu-Knit absorbable hemostat, with effectiveness against cardiovascular and peripheral vascular bleeding. If these preclinical results are confirmed in clinical trials, this highly effective patch with a topical application requiring less than 30 seconds is likely to prove useful in many clinical settings.

Evaluation of Perivascular Adhesion Formation in New Zealand White Rabbits Using Oxiplex and DuraSeal Xact Adhesion Barrier System.

BACKGROUND: Adhesion formation after spine surgery is a result of normal wound healing that may place patients at increased risk for complications during revision surgery. Preventing adhesions could reduce the risk of complications during revision surgery, and possibly reduce the need for revision procedures. This study evaluates the ability of DuraSeal Xact Adhesion Barrier System (DSX) (Covidien, Mansfield, Massachusetts) and Oxiplex/SP gel (OX) (FzioMed, San Luis Obispo, California) to affect the extent and severity of postoperative perivascular adhesion development in an anterior spinal surgical rabbit model. METHODS: We determined the extent and severity of postoperative adhesion development 34 days after surgery in 12 male New Zealand White rabbits randomly assigned to intraoperative treatment with either DSX or OX, or to an untreated control group. Adhesion severity and extent were scored on scale from 0 (none) to 3 (severe). RESULTS: The extent and severity of adhesions in the DSX group were significantly less than in the untreated control group. The DSX group mean extent score was 1.3 ± 0.5 (vs 2.5, P = .01) and the mean severity score was 1.25 ± 0.5 (vs 2.8, P = .005). The extent and severity of adhesions in the OX group were not significantly different from the control group. CONCLUSION: In this study, we found DSX to be the most effective compound in preventing adhesion formation after anterior spine surgery. CLINICAL RELEVANCE: Extrapolating these results in rabbits to humans, less scarring between the major blood vessels could decrease the rate of complications in revision spine procedures.

Development of a method for the evaluation of wound tensile strength in cynomolgus macaques.

INTRODUCTION: Numerous in vivo wound healing models have been developed to evaluate the potential of drugs to affect the processes involved in wound healing, including angiogenesis. The majority of these models are frequently conducted in rodents, rabbits, and pigs and are terminal in nature. Due to the species specificity of many biotherapeutic molecules under development a non-terminal model in the cynomolgus monkey was evaluated in this study. METHODS: To evaluate wound tensile strength, 3 full thickness skin incisions (2 cm long and 3 mm deep) were created on each side of the midline with a micro-fine surgical scalpel. Wounds were closed with SteriStrips applied over Mastisol, and covered with Tegaderm. The animals were then fitted with primate jackets. In Study 1, 3 male macaques per group received daily intramuscular injections of saline or dexamethasone (1 mg/kg) from Day-1 through Day 11. In Study 2, 3 males macaques per treatment group received a single intravenous injection of saline or anti-VEGF mAb (20 mg/kg) on Day-1. In Studies 1 and 2 wounds were created on Day 1. In Study 3, 3 males and 3 female macaques per treatment group received anti-VEGF mAb (20 mg/kg) on Days 1, 8, 15 and 22. In study 3, wounds were created on Day 12. On Days 4, 8, and 11 relative to wound creation, two randomized incisions per animal were evaluated with a Biomechanical Tissue Characterization System. RESULTS: In Study 1, there was a statistically significant reduction in wound strength in the dexamethasone treated group on Day 11 as compared to saline negative control. There was a statistically significant reduction in wound strength in the anti-VEGF mAb treated animals on Day 8 as compared to saline in Study 2. Statistical evaluation of wound strength between saline treated animals and the anti-VEGF mAb treated animals showed a significant reduction in wound strength in the anti-VEGF mAb treatment group on Day 8 (Fig. 3). In all studies there were open wound sites at the time of evaluation, which ranged from 6 to 50% on Day 4, 3 to 17% on Day 8, and 6% on Day 11. DISCUSSION: These studies demonstrate a potential method for evaluating the strength of sterile incisional wounds in the cynomolgus monkey, which allows for multiple evaluations of wound strength within an animal over time in a non-terminal model. Dexamethasone and anti-VEGF mAb produced significant reductions in wound healing on Day 11 and 8, respectively. It was inconclusive whether the number of open incisional sites was related to the test article, incomplete closure at the time of surgery, or movement of the animals in the primate jacket.