Changes in exhaled 13CO2/12CO2 breath delta value as an early indicator of infection in intensive care unit patients.

Background: We have developed a new, noninvasive predictive marker for onset of infection in surgical intensive care unit (ICU) patients. The exhaled CO2/CO2 ratio, or breath delta value (BDV), has been shown to be an early marker for infection in a proof of concept human study and in animal models of bacterial peritonitis. In these studies, the BDV changes during onset and progression of infection, and these changes precede physiological changes associated with infection.