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BACKGROUND: Closure of the peritoneal cavity mandates careful re-approximation of the fascial edges in order to prevent incisional hernia. Injury to the bowel, and subsequent significant morbidity or even mortality, can occur due to insufficient visualization during closure. Devices currently employed to protect the bowel from inadvertent needle puncture and facilitate closure, such as the malleable or Glassman FISH^TM viscera retainer, must be removed prior to fascial closure, risking bowel loop ensnarement within the last tied sutures. Thus, we developed a novel implantable visceral “shield” fabricated from a rapidly degradable, biocompatible polymer (made from a FDA approved monomer that is part of the natural glycolytic pathway) to address this need.
METHODS: Two-millimeter thick CC-dihydroxyacetone (CC-DHA) sheets were fabricated into individual 8 mm diameter by 2 mm thickness disc-shaped wafers, each weighing 50-100 mg. In vitro assays demonstrated 96% degradation of the polymer wafer after 4 hours in PBS. C57BL/6 mice were used in an in vivo murine model to evaluate the effectiveness of CC-DHA. A midline laparotomy was performed, and wafers were placed into the abdomen. Each wafer was tagged with a suture prior to implantation into the intraperitoneal cavity with the bowel subjacent. Closure was completed with a running 5-0 nylon suture. At 3, 6, 12, and 24 hours after implantation, animals were sacrificed, and wafers were explanted for analysis. A sub-cohort of mice were housed for 7 days post-operatively in order to further assess any side effects of toxicity following CC-DHA implantation.
RESULTS: The CC-DHA polymer “shield” demonstrated enough flexibility and resistance to withstand direct needle puncture. By 6 hours post-operatively, the wafers were nearly completely hydrolyzed and degraded with only 0.23% (weight) of the original 50 mg, 50 mm²-sized wafers remained on average in the intraperitoneal cavity. After 12 and 24 hours, no CC-DHA polymer was detectable in any animals, as all CC-DHA had degraded under physiological conditions into safe glycolytic metabolites. This safe degradation and intraperitoneal fluid status was subsequently confirmed at 24 hours. All mice recovered appropriately at all time points. Finally, in the cohort maintained for 7 days, no evidence of toxicity was observed, as all mice demonstrated appropriate feeding, weight maintenance, and grooming post-operatively. No mice required re-exploration.
CONCLUSIONS: We have successfully created a rapidly degradable biocompatible device, which can be left in situ as a visceral “shield.” Furthermore, DHA is a FDA-approved moiety, and under physiological conditions, DHA-based polymers rapidly hydrolyze and can be safely eliminated from the body via a natural metabolic pathway; thereby, reducing the risk of inflammation and local toxicity. This innovative CC-DHA exhibits resistance to withstand direct needle puncture with a compelling degradation profile to facilitate safe, rapid, and protective fascial closure. Additionally, CC-DHA appears to have mucin-mimetic properties, which may also result in decreased bowel adhesions. Hence, these characteristics make this novel material extraordinarily useful as both a physical barrier to prevent inadvertent bowel injury during fascial closure as well as a conceivable means to decrease post-operative intra-abdominal scarring.