Adhesion Prevention in General Surgery : A Next - Generation PEG Based Adhesion Barrier

Study Objective. Evaluation of SprayShieldTM Adhesion Barrier System efficacy in the rat cecum and porcine abdominal sidewall adhesion model. Design. Rat Model: Evaluation of SprayShieldTM adhesion prevention relative to Control animals. Porcine Model: Evaluation of SprayShieldTM Adhesion Barrier System and SprayGelTM Adhesion Barrier vs. Control in a porcine abdominal sidewall injury model. Setting. Independent research facility, University research facility Patients. Rats and virgin female pigs. Interventions. Rat Model: Following cecum and sidewall injury animals are randomized to either SprayShieldTM Adhesion Barrier application or control (10 per group). Adhesion evaluation at 14 days. Porcine Model: Following open bilateral pericolic gutter sidewall and uterine horn injuries, midline incisions were closed and animals randomized to either control, or to laparoscopic SprayShieldTM adhesion barrier or SprayGelTM application. Adhesion evaluation at 10-14 days. Measurements and Main Results. Rat Model: Adhesion incidence: Control = 80%, SprayShieldTM adhesion barrier = 10% (p = 0.0017). Adhesion extent: Control = 2.0 + 0.4, SprayShieldTM adhesion barrier = 0.1 + 0.1 (p < 0.008), Adhesion severity: Control = 1.6 + 0.27, SprayShieldTM adhesion barrier = 0.1 + 0.1 (p < 0.008). Porcine Model: SprayShieldTM adhesion barrier reduced adhesion area to injured sidewalls 83% relative to control (p < 0.014), and 64% relative to SprayGelTM. In addition, SprayShieldTM adhesion barrier reduced adhesion incidence by 50%, and adhesion severity by 26%, relative to Control. Conclusion. While both hydrogel products performed better than controls, the SprayShieldTM Adhesion Barrier System, as a nextgeneration, sprayable, adhesion prevention product, appears to have distinct advantages over SprayGelTM adhesion barrier. 50% of traumatized area. Adhesion severity was scored as 0) No adhesions; 1) Mild adhesions, easily dissected; 2) Moderate adhesions, blunt dissection required; and 3) Dense adhesions, sharp dissection required. Porcine Abdominopelvic Adhesion Study The objective of this study was to evaluate the adhesion prevention efficacy of laparoscopically applied SprayShieldTM adhesion barrier and SprayGelTM adhesion barrier verses Control in a porcine abdominal sidewall injury model. A total of 18 virgin female hogs (33.2–39.4 kg) were evaluated in this model first proposed by Ferland et al (2001). Using aseptic technique, animals received adhesiogenic injuries via laparotomy, followed by subsequent laparoscopic treatment. A single midline abdominal incision was created, animals were placed in Trendelenburg position, and the bladder was aspirated. Dry surgical gauze, towels and retractors were used to facilitate adhesion formation. The parietal peritoneum of the pericolic gutter was then sharply excised to expose an area about 5 cm x 4 cm on the pelvic sidewall. Monopolar electrocautery (Valley lab Force 2, 35 watts coag) was used to score the exposed muscle (Figure 1). Following the injury of one sidewall, the corresponding uterine horn was transected at its midpoint with electrocautery and end-to-end re-anastomosed using two interrupted 3-0 braided polyester sutures. The same injuries were then performed on the contra lateral pericolic gutter and uterine horn, and the cavity was rinsed with several hundred ml saline that was suctioned out. Trocars were then placed, and the laparotomy was closed in layers with continuous braided 0 polyester suture. Following laparotomy closure the abdomen was insufflated to 10 mmHg with CO2, and animals were randomized to receive either SprayShieldTM adhesion barrier (n=8), SprayGelTM adhesion barrier (n=7), or good surgical technique (Control, n=3). Animals randomized to SprayShieldTM adhesion barrier or SprayGelTM treatment had the hydrogel laparoscopically applied via a 5 mm port to the injured areas of the peritoneal sidewalls and uterine horns using the air assisted applicator (Figure 2). All treated sites were rinsed with saline, and excess saline Another difference is the colorant used that allows for visualization during application. SprayShieldTM adhesion barrier contains FD&C Blue #1, compared to methylene blue in SprayGelTM. While methylene blue is frequently used in gynecological procedures, there are reports of sensitization (Keller, et al. 2007). The objective of the changes was to take a product with proven safety and efficacy, and make it easier to prepare, and even more efficacious with potential superior mechanical bonding to underlying adhesiogenic tissues and a faster absorption rate. This report details the evaluation of SprayShieldTM adhesion barrier in the rat cecum adhesion model, and the comparison of SprayShieldTM adhesion barrier and SprayGelTM adhesion prevention efficacy in a clinically relevant porcine model of abdominal surgery. MAtERiAlS ANd MEthodS All surgical procedures were conducted in accordance with the regulations and with the approval of the Animal Care and Use Committees. Rat Cecum Adhesion Study The objective of this study was to evaluate the SprayShieldTM Adhesion Barrier System as compared to surgical control (no treatment) on adhesion development after surgical injury of the cecum and abdominal wall of rats. Using aseptic techniques, a total of twenty rats received caudal ventral midline incisions, followed by cecum exteriorization. An approximate 2 cm2 area of serosa of the lateral side of the cecum was abraded using dry sterile gauze until petechial hemorrhage was observed, and a 2 x 1 cm portion of the corresponding sidewall was abraded with a #10 scalpel blade to the point of muscle disruption. The surgeons were blinded to the treatment assignment until completion of the injury procedures. Following injury animals were randomized to receive SprayShieldTM adhesion barrier on the injured cecum and sidewall, or to remain as controls with no further treatment. All SprayShieldTM adhesion barrier and Control animal abdomens were rinsed with 5ml sterile saline, and animals had the muscle layer and skin closed separately using 4-0 PDS suture. All animals were returned to their cages and monitored daily for general health. Body weights were recorded at pretreatment and at termination at 14 days. At termination animals were euthanized with CO2 inhalation, the peritoneal cavity was opened, and the viscera examined by a blinded reviewer for adverse changes. Adhesions between the cecum and sidewall were assessed for number, and extent per the following: 0) No adhesions; 1) Adhesions up to 25% of traumatized area; 2) 25-50% of traumatized area; and 3) > figure 1: Sidewall injury in one pericolic gutter via laparotomy. Resection of peritoneum followed by cautery scoring of the underlying muscle.