Self-expanding foam for prehospital treatment of intra-abdominal hemorrhage: 28-day survival and safety

Intracavitary noncompressible hemorrhage remains a significant cause of preventable death on the battlefield and in the homeland. We previously demonstrated the hemostatic efficacy of an in situ self-expanding poly(urea)urethane foam in a severe, closed-cavity, hepatoportal exsanguination model in swine. We hypothesized that treatment with, and subsequent explantation of, foam would not adversely impact 28-day survival in swine. Following a closed-cavity splenic transection, animals received either fluid resuscitation alone (control group, n = 6) or resuscitation plus foam treatment at doses of 100 mL (n = 6), 120 mL (n = 6), and 150 mL (n = 2). Foam was allowed to polymerize in situ and was explanted after 3 hours. The animals were recovered and monitored for 28 days. All 18 animals in the 100-mL, 120-mL, and control groups survived to the 28-day endpoint without complications. The 150-mL group was terminated after the acute phase (n = 2). En bloc explantation of the foam took less than 2 minutes and was associated with millimeter-sized remnant particles. All foam animals required some level of enteric repair (imbrication or resection). Excluding the aborted 150-mL group, all animals survived, with no differences in renal or hepatic function, serum chemistries, or semiquantitative abdominal adhesion scores. Histologic analysis demonstrated that remnant particles were associated with a fibrotic capsule and mild inflammation, similar to that of standard suture reaction. In addition, safety testing (including genotoxicity, pyrogenicity, and cytotoxicity) was performed consistent with the ISO-10993 standard, and the materials passed all tests. For a distinct dose range, 28-day recovery after foam treatment and explantation for noncompressible, intra-abdominal hemorrhage is not associated with significant physiologic or biochemical evidence of end-organ dysfunction. A foam volume exceeding the maximum tolerable dose was identified. Bowel repair is required to ensure survival.