Noninvasive Infection Detection in Mechanically Ventilated Adults via the Breath Delta Value
The breath delta value (i.e. 13CO2/12CO2 or BDV) is a non-invasive marker for altered metabolism due to infection. Infection detection is achieved by monitoring stable isotopes of carbon in exhaled CO2 termed the BDV. Exhaled breath samples may be taken non-invasively from the ventilator exhaust and isotopic CO2 analyzed. Animal studies and a pilot study in the pediatric intensive care unit (ICU) indicate that the BDV may be an indicator for the onset of infection. We report here the variation in the BDV in critically ill mechanically ventilated adults with and without infection.
Subjects were given the standard of care, and breath was sampled every 8 hours for 72 hours. BDV was determined using the Canary BDV monitor (Isomark, LLC, Madison, WI) currently under development and not yet cleared by the FDA. Infection was defined as either clinically diagnosed sepsis and/or pneumonia. Trends were analyzed using the mixed procedure accounting for autocorrelation of repeated measures (SAS version 9.2, SAS Inst. Cary, NC). Differences were considered significant with p<0.05.
Table 1 shows the demographics of the subjects. Figure 1 shows the BDV trends over time. The trends remained stable over time and did not increase or decrease significantly from the first sample. The BDV from subjects with an infection was significantly lower than subjects without infection at all time-points. The mean BDV was -21.07%o (0.19 SEM) in subjects without infection and -23.39%o (0.18 SEM) in subjects with an infection. Conclusion:
The BDV is significantly lower in critically ill mechanically ventilated adults with an infection than in similar subjects without an infection. These data suggest that BDV may be a marker for infection in critically ill mechanically ventilated adults. Further testing is underway, to determine if the BDV is a useful marker for the onset of infections in the ICU.
Table 1: Demographics
Figure 1: Breath delta value over time in critically ill mechanically ventilated adults with and without infection. Data are reported as the average, and error bars represent the standard error of the mean. Asterisks denote significant differences with p<0.05.
Isomark, LLC: Grant Investigator, Research support
E. Wald, None
D. Butz, Isomark, LLC: Grant Investigator, Member and Shareholder, Salary