[Correlation between the shock index and the anaerobic index].

Abstract

Background: Shock is defined as an acute circulatory insufficiency that causes cellular dysfunction. The shock index (SI) and the anaerobic index or the relationship between the veno-arterial gradient of carbon dioxide and the difference between the arterial and venous content of O₂ [∆P(v-a)CO2/ΔC(a-v)O2] are markers of systemic hypoperfusion.

Objective: To determine if there is a correlation between the SI and the anaerobic index in patients with circulatory shock.

Material and methods: Observational and prospective study in patients with circulatory shock. The SI and the anaerobic index were calculated at admission to the intensive care unit (ICU) and during their stay. Pearson's correlation coefficient was calculated and the association of SI with mortality was explored with bivariate logistic regression.

Results: 59 patients aged 55.5 (± 16.5) years, 54.3% men, were analyzed. The most frequent type of shock was hypovolemic (40.7%). They had SOFA score: 8.4 (± 3.2) and APACHE II: 18.5 (± 6). The SI was: 0.93 (± 0.32) and the anaerobic index: 2.3 (± 1.3). Global correlation was r = 0.15; at admission r = 0.29; after 6 hours: r = 0.19; after 24 hours: r = 0.18; after 48 hours: r = 0.44, and after 72 hours: r = 0.66. The SI > 1 at ICU admission had an OR 3.8 (95% CI: 1.31-11.02), p = 0.01.

Conclusions: The SI and the anaerobic index have a weak positive correlation during the first 48 hours of circulatory shock. The SI > 1 is a possible risk factor for death in patients with circulatory shock.