Background: We have previously described the hemostatic efficacy of a self-expanding polyurethane foam in lethal venous and arterial hemorrhage models. A number of critical translational questions remain, including prehospital diagnosis of hemorrhage, use with diaphragmatic injury, effects on spontaneous respiration, the role of omentum, and presence of a laparotomy on foam properties.
Methods: In Experiment 1, diagnostic blood aspiration was attempted through a Veress needle before foam deployment during exsanguination (n = 53). In Experiment 2: a lethal hepatoportal injury/diaphragmatic laceration was created followed by foam (n = 6) or resuscitation (n = 10). In Experiment 3, the foam was deployed in naïve, spontaneously breathing animals (n = 7), and respiration was monitored. In Experiments 4 and 5, the foam was deployed above (n = 6) and below the omentum (n = 6) and in naïve animals (n = 6). Intra-abdominal pressure and organ contact were assessed.
Results: In Experiment 1, blood was successfully aspirated from a Veress needle in 70% of lethal iliac artery injuries and 100% of lethal hepatoportal injuries. In Experiment 2, in the presence of a diaphragm injury, between 0 cc and 110 cc of foam was found within the pleural space. Foam treatment resulted in a survival benefit relative to the control group at 1 hour (p = 0.03). In Experiment 3, hypercarbia was observed: mean (SD) Pco2 was 48 (9.4) mm Hg at baseline and 65 (14) mm Hg at 60 minutes. In Experiment 4, abdominal omentum seemed to influence organ contact and transport in two foam deployments. In Experiment 5, there was no difference in intra-abdominal pressure following foam deployment in the absence of a midline laparotomy.
Conclusion: In a series of large animal studies, we addressed key translational issues surrounding safe use of foam treatment. These additional data, from diagnosis to deployment, will guide human experiences with foam treatment for massive abdominal exsanguination where no other treatments are available.