Use of StO2 Monitoring In Conjunction with Sepsis Screening Tool to Improve Early Recognition of Sepsis
Author(s):
Natacha Villegas, The University of Texas HSC Houston TX; John Holcomb, The University of Texas HSC Houston TX; Charles Wade, The University of Texas HSC Houston TX; Michael Swartz, The University of Texas HSC Houston TX; Laura Moore, The University of Texas HSC? Houston TX
Background: In the United States, sepsis develops in 10% of patients admitted to ICUs, and in 2% of all hospitalized patients, with a total of 750,000 cases annually. It was the most expensive condition treated in 2011, and the estimated mortality rate from septic shock is 20-30%.
Sepsis is defined as meeting the Systemic Inflammatory Response Syndrome (SIRS) criteria plus suspected or confirmed infection. New methods are needed to detect sepsis earlier, as studies show that early interventions lead to better outcomes. Two new devices have been developed to detect sepsis: the Sepsis Screening Tool (SST), a validated scoring system (figure 1), and the StO2 (tissue oxygen saturation) monitor.
Hypothesis: We hypothesize that the combined use of the Sepsis Screening Tool and StO2 monitoring could allow for earlier recognition of sepsis in patients admitted to the shock trauma ICU (STICU).
Methods: Sepsis leads to vasogenic shock, which results in hypoperfusion that can be detected by the StO2 Monitor. This device works by placing a sensor in the thenar eminence, where near infrared spectroscopy detects the percent hemoglobin saturation in the tissues, not in the arteries as does the pulse oximeter. Sepsis was considered present if the StO2 values were below 75% or above 90%, and for the SST if the score was above 4.
Sepsis Screening Tool and StO2 values were collected daily from patients admitted to the Memorial Hermann Hospital STICU in a period of 10 weeks. The outcome of interest was the development of sepsis during the patients’ stay at the STICU, based on the SIRS criteria (Gold Standard). The results from the combined use of Sepsis Screening Tool with StO2 monitoring were compared to the use of the Sepsis Screening Tool by itself.
Results: A total of 91 patients were included in the study, with a mean age of 47, 6 total deaths, 36% female participants, and sepsis incidence of 26%. As per the statistical analysis, the Sepsis Screening Tool by itself had a specificity of 83%, while the combined test had a specificity of 96% (p-value: 0.0002). The difference in sensitivity for the tests was not statistically significant (p-value: 0.1398).
Conclusions: The improved specificity allows for the earlier detection of sepsis with more confidence. This has powerful implications as it could lead to earlier interventions and thus better outcomes. As sepsis continues to be an important threat to patients in the ICU, a protocol that improves sepsis outcomes could have a tremendous impact in ICU costs, morbidity and mortality.