No Need to Count: An Implantable and Rapidly Resorbably Elastomeric Shield for Laparatomy Closure
Omer Kaymakcalan, MD1, Julia Jin, BS1, Zhexun Sun, MS2, Nicole Ricapito, PhD2, Sarah Karinja, BA1, Andrew Abadeer, MEng1, Jaime Bernstein, BS1, Yoshiko Toyoda, BA1, John Morgan, PhD1, David Putnam, PhD2, Jason Spector, MD1.
1Weill Cornell Medical College, New York, NY, USA, 2Cornell University, Ithaca, NY, USA.
BACKGROUND: With over 1.5 million laparotomies performed yearly in the US and in increasingly complicated patients, there is growing appreciation and utilization of component separation by plastic surgeons for closure of the difficult abdomen. Presently, standard practice during the laparotomy closure is shield the bowel from the suture needle through use of the PVC Glassman Visceral Retainer (Fish ®) or metal ribbon retractor. These tools however remain cumbersome and require removal prior to placement of the final fascial sutures. This leaves the bowel at risk for injury when abdominal pressure is increasing and visualization is poorest or conversely may leave the closure at risk as insufficient fascial ‘bites' may be taken by the surgeon in attempt to avoid the bowel. To address this challenge, we have synthesized a flexible and rapidly-degrading elastomer, CC-DHA from dihydroxyacetone, polyethylene glycol and glycerol that under surgical conditions withstands needle puncture and completely shields the bowel during closure with no adverse effects.
METHODS: Midline laparotomies were performed in male C57BL/6 mice with a CC-DHA disk or saline control placed on the viscera. Needle puncture testing was performed with a GS-21 needle at 90 degrees, to evaluate the force required to puncture the CC-DHA disk at 0, 5, 10, and 20 minutes of exposure to the surface of the viscera. In another cohort the laparotomy was closed, and mice were evaluated at 3, 6, 9, 24 hours and 14 days post-operatively. Compression testing was performed to evaluate the flexibility and elastomeric properties of the disks.
RESULTS: Needle puncture testing revealed a force of 0.52 +/- 0.16 N, .69 +/- 0.05 N and 0.048 +/- 002 N for the CC-DHA, a rubber band, rat small bowel respectively, p<0.05 for the difference between the CC-DHA and small bowel. In order to demonstrate that the material retained sufficient strength in vivo for the time required for standard fascial closure (approximately 10-20 minutes), shields were placed intraabdominally over the viscera for 0, 5, 10, and 20 minutes and puncture testing performed demonstrating a non-significant decrease in resistance to puncture. The CC-DHA however maintained a statistically significant elevation in force required to puncture when compared to rat small bowel p<0.05. By 3 hours after implantation, 1 H NMR spectroscopy identified CC-DHA degradation products of glycerol ethoxylate and tri(ethylene glycol) (all natural non-toxic metabolites) in the peritoneal fluid, blood, and urine, demonstrating rapid elimination of the dissolved shield. Mice maintained for 14 days showed no evidence of gross or histologic toxicity or peritoneal adhesion formation compared to controls. Compression testing yielded a Young's modulus of 46.4 +/- 9.2 kPa and demonstrated it withstands repeated compression.
CONCLUSIONS: CC-DHA is a promising, safe, bio-compatible elastomer, which can replace current standards Glassman Visceral Retainer (Fish ®) or ribbon retractor, to completely shield the viscera during the entirety of peritoneal closure. Further, this same material can be used to shield other sensitive areas and from inadvertent needle puncture, such as a breast implant, giving this novel material significant utility across a wide variety of surgical procedures.
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