Background: Antithrombin (AT) levels have been suggested as being predictive of outcome in intensive care unit (ICU) patients with septic shock. We investigated the time course of AT levels in a surgical ICU and tested the hypothesis that AT levels may be associated with morbidity and increased mortality rates in a cohort of surgical ICU patients.
Methods: Three-hundred-twenty-seven consecutive patients admitted to the ICU with an estimated length of stay more than 48 h were included. AT levels were measured daily.
Results: On admission to the ICU, AT levels were below the lower limit of normal in 84.1% (n = 275) of patients and increased significantly by 48 h after admission to reach normal values by the 7th ICU day in patients who never had sepsis (n = 208). This increase in AT levels was delayed in patients with sepsis. Patients with severe sepsis (n = 55) had consistently lower AT levels compared with other patients. Patients with lower AT levels were more likely to need blood products and had a greater maximum degree of organ dysfunction in the ICU than did other patients. The ICU length of stay was similar, regardless of the AT level on admission. Admission AT levels were not associated with increased ICU mortality in a multivariable analysis.
Conclusions: AT levels are low on admission to the ICU, regardless of the presence of sepsis. Although associated with the degree of organ dysfunction and the severity of sepsis, AT levels were not independently associated with worse outcome in this group of surgical ICU patients.