In vivo evaluation of the chitosan-based haemostatic agent Omni-stat® in porcine liver resection and in liver injury.

Background: Omni-stat®, a polysaccharide made by de-acetylation of chitin, is currently in use as a battlefield topical haemostat. This experimental study undertakes the first evaluation of Omni-stat in an in vivo porcine hepatectomy and liver trauma model.

Methods: A model of sequential liver resection was employed: following liver resection, further resections were undertaken in the same animal provided that there was cessation of bleeding from the earlier resection and that haemodynamic stability was maintained. An additional liver trauma injury was undertaken after completion of all resections. Data were collected on heart rate, blood pressure, haematocrit, resection volumes, blood loss and the efficacy of Omni-stat in haemostasis.

Results: Eight minor resections and 12 major resections were undertaken. Topical application of Omni-stat to raw post-transection surfaces immediately upon completion of resection achieved complete haemostasis with a single application in 14 of 15 (93%) resections. There was no recurrence of bleeding during the 5-hour protocol. The median time for cessation of bleeding after resection in the Omni-stat group was 3 min (range 3-6). This was not significantly different from time to cessation of bleeding in 5 control resections. There was no difference in blood loss or haemodynamic parameters. Respiratory rate was significantly faster after application of Omni-stat. In 2 liver lacerations, Omni-stat was effective in achieving cessation of haemorrhage.

Conclusion: Omni-stat is an effective haemostat in experimental in vivo porcine liver resection and liver trauma. Further evaluation is required to assess its physiological absorption profile in man and its comparative efficacy against commercially established agents.