UroToday - Hemostatic agents and tissue sealants are routinely used to prevent excess blood loss and in reconstruction during surgical repair. Over the past 20 years, a number of hemostatic agents and tissue sealants have been developed and are currently used in various surgical disciplines. Hemostatic agents act to stop bleeding either mechanically or by augmenting the coagulation cascade, where as tissue sealants are products that bind to and close defects in tissue. A recent overview on these products was M. A. Traver and D. G. Assimos from Wake Forest. The review is published in the summer 2006 issue of Reviews in Urology.

Fibrin glue was approved by the FDA in 1998 and provides topical hemostasis, has sealant properties, and promotes tissue approximation. Fibrin glue mimics the final steps of the coagulation cascade. In the presence of thrombin, fibrinogen is converted to fibrin and is delivered in a double-barrel syringe onto a dry tissue bed. Urologic applications include the management of urinary fistulas and surgical complications such as iatrogenic urinary tract injuries during gynecological procedures. A major indication is in the realm of nephron sparing surgery- as in partial nephrectomy. Use has become common in pediatric reconstructive surgery such as hypospadias repair augmentation. Currently available fibrin glue preparations include: Tissel, Hemaseel, Beriplast P, Bolheal, and Quixil.

Gelatin Matrix/Thrombin Sealants such as Floseal is composed of thrombin and a gelatin matrix that is manufactured by extracting collagen from bovine corneal tissue. Both components work independently and synergistically to promote clot formation at the bleeding site. The granular nature of the compound conforms to the wound's shape. The granules swell 10% - 20%, causing tamponade in the wound bed on contact with blood or other fluid. This reduces bleeding and provides a matrix on which a clot can form. The product does not require a dry surgical site; in fact it requires some blood to be present. Main applications include nephron sparing surgery and traumatic reconstruction of the kidney.

Cyanoacrylate, better known as "super glue", was first used as a tissue sealant in the 1940's but it generated an intense local inflammation that inhibited its use. Synthetic cyanoacrylate (Dermabond) was approved by the FDA in 1998 for skin closure. Several authors have reported success with the injection of cyanoacrylate into troublesome urinary fistulas.

BioGlue is a 2-component system consisting of purified bovine serum albumin and glutaraldehyde. Glutaraldehyde bridges the amine groups from bovine serum albumin to intracellular matrix proteins of the target tissue forming a covalent bond between the tissue and adhesive. The material is used on a dry field and polymerization occurs in 3 minutes. There has been data from the vascular surgery literature in which vascular anastomosis in which BioGlue was the only method of approximation.

Polyethylene Glycol Hydrogels, such as CoSeal and Advaseal, polymerize at the site of application. They were approved by the FDA in 2000 as a pulmonary sealant. The material has been used with success in animal models of partial nephrectomy.

In summary, there are a number of tissue sealants and hemostatic agents available to facilitate urologic surgery. The efficacy of some applications has been established, but many are awaiting further evaluation and confirmation. The authors anticipate that further product development and refinement is on the horizon.

Michael A Traver, MD and Dean G Assimos, MD
Reviews in Urology. 2006; Vol 8. No. 3:104-111

Reviewed By UroToday Contributing Editor Michael J. Metro, M.D.

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