A quick back and forth with the authors on why hirudin might prove to be more effective than ATIII in sepsis:
"Hirudin is a small peptide inhibitor and more likely to equilibrate with the extrvascular space as compared to the protein inhibitor antithrombin.
Wolfram Ruf"
This of course, is opinion, without a lot of clinical data either way.
While other thrombin inhibitors (hirudin or others) might ultimately prove to be more effective, these data are much more suggestive than not that ATIII should be expected to have good effect in sepsis.
Best,
MTB