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Safety Evaluation of New Hemostatic Agents, Smectite Granules, and Kaolin-Coated Gauze in a Vascular Injury Wound Model in Swine

Kheirabadi, Bijan S. PhD; Mace, James E. MD; Terrazas, Irasema B. MS; Fedyk, Chriselda G. MS; Estep, J. Scot DVM; Dubick, Michael A. PhD; Blackbourne, Lorne H. MD

The Journal of Trauma: Injury, Infection, and Critical Care: February 2010 - Volume 68 - Issue 2 - p 269-278
doi: 10.1097/TA.0b013e3181c97ef1
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Background: In 2007, a potent procoagulant mineral called WoundStat (WS), consisting of smectite granules, received clearance from the Food and Drug Administration for marketing in the United States for temporary treatment of external hemorrhage. Previously, we found that microscopic WS particles remained in the injured vessels that were treated, despite seemingly adequate wound debridement. Thus, we investigated the thromboembolic risk of using WS when compared with kaolin-coated gauze, Combat Gauze (CG); or regular gauze, Kerlix (KX) to treat an external wound with vascular injuries in pigs.

Methods: The right common carotid artery and external jugular vein of pigs were isolated and sharply transected (50%). After 30 seconds of free bleeding, the neck wounds were packed with WS, CG, or KX and compressed until hemostasis was achieved (n = 8 per group). Wounds were debrided after 2 hours, and vascular injuries were primarily repaired with suture. Blood flow was restored after infusing 1 L of crystalloid (no heparin or aspirin) and the wounds were closed. Two hours later, computed tomographic angiography was performed, and the wounds were reopened to harvest the vessels. The brains and lungs were recovered for gross and microscopic examination after euthanasia.

Results: No differences were found in baseline measurements. Thrombelastography showed similar hypercoagulability of the final blood samples when compared with baselines in all groups. All vessels treated with KX or CG were patent and had no thrombus or blood clot in their lumen. In contrast, seven of eight carotid arteries and six of eight jugular veins treated with WS developed large occlusive red thrombi and had no flow. Small clots and WS residues were also found in the lungs of two pigs. Histologically, significant endothelial and transmural damage was seen in WS-treated vessels with luminal thrombi and embedded WS residues.

Conclusion: WS granules caused endothelial injury and significant transmural damage to the vessels that render them nonviable for primary surgical repair. The granules can enter systemic circulation and cause distal thrombosis in vital organs. More relevant in vitro and in vivo safety tests should be required for clearance of new hemostatic agents.

From the US Army Institute of Surgical Research, Ft. Sam Houston, Texas.

Submitted for publication August 26, 2009.

Accepted for publication November 5, 2009.

Supported by the US Army Medical Research and Materiel Command.

The opinions or assertions expressed herein are the private views of the authors and are not to be construed as official or as reflecting the views of the US Department of the Army or the US Department of Defense.

Address for reprints: Bijan S. Kheirabadi, PhD, 3400 Rawley E. Chambers Avenue, Building No. 3611, Fort Sam Houston, TX 78234-6315; email: bijan.kheirabadi@us.army.mil.

© 2010 Lippincott Williams & Wilkins, Inc.