Patients with severe sepsis vary markedly in their ability to generate activated protein C.
Activated protein C (APC) supplementation significantly reduces mortality in patients with severe sepsis, presumably by down-regulating coagulation, inflammation, and apoptosis. In vivo, endogenous APC is generated from protein C (PC) "on demand" in response to elevated thrombin levels. Thrombomodulin and endothelial cell protein C receptor are endothelial receptors required to generate APC endogenously. Since these receptors may be down-regulated in sepsis, we measured plasma markers of APC generation in 32 patients with severe sepsis to determine whether APC generation is impaired and whether markers of APC generation correlate with 28-day mortality. Relative to normals, all patients had elevated F1 + 2 and thrombin-antithrombin complex (TAT) levels (markers of thrombin generation and inhibition, respectively), and 28 of 32 patients had reduced PC levels. In 20 patients, APC levels paralleled elevated F1 + 2 levels, whereas 12 patients had low APC levels despite elevated F1 + 2 levels, suggesting that APC generation is impaired in the latter. No significant differences exist between survivors and nonsurvivors with respect to baseline PC levels, F1 + 2 levels, and APACHE II (acute physiology and chronic health evaluation) scores. Baseline APC levels were higher in survivors (P = .024), and baseline F1 + 2/APC ratios were lower in survivors (P = .047). Larger studies are warranted to establish whether APC generation profiles aid in managing sepsis.
Liaw
Patricia C Y
PC
Department of Medicine, McMaster University, Hamilton, Ontario, Canada. pliaw@thrombosis.hhscr.org
Esmon
Charles T
CT
Kahnamoui
Kamyar
K
Schmidt
Shelley
S
Kahnamoui
Sarah
S
Ferrell
Gary
G
Beaudin
Suzanne
S
Julian
Jim A
JA
Weitz
Jeffrey I
JI
Crowther
Mark
M
Loeb
Mark
M
Cook
Deborah
D
D018806:APACHE; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D004789:Enzyme Activation; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011486:Protein C / Q000378:metabolism* / Q000627:therapeutic use; D018805:Sepsis / Q000097:blood* / Q000188:drug therapy / Q000401:mortality; D016019:Survival Analysis; D000515:alpha 1-Antitrypsin / Q000378:metabolism
D011486:Protein C; D000515:alpha 1-Antitrypsin