Carbon-12 and carbon-13 are naturally-abundant isotopes in exhaled breath carbon dioxide. The ratio of carbon-13 to carbon-12 in exhaled breath is known as the breath delta value (BDV). This study is seeking to determine if the breath delta value of critically ill adults is an early indicator of the onset of infection that may lead to sepsis.

Sepsis is a major complication for any patient, and its management is an acknowledged challenge for intensivists. Sepsis has unpredictable onset and progression, and is a leading cause of death in ICUs with a mortality rate of 30-50%. Annually in the US, 1.4M cases involve hospitalization, 750,000 cases of severe sepsis or septic shock, and ~260,000 cases of sepsis related death have been reported in recent years. Current experience of UF Health investigators in surgical ICUs is 1 -2 sepsis, severe sepsis, or septic shock patients per day, of which ~10% are trauma patients. Of trauma patients, ~8% develop sepsis during their ICU stay.

Breath delta value is hypothesized to be a biomarker of infection. Breath delta value is not a defined clinical outcome related to human health, because this study is seeking to establish breath delta value as a biomarker of infection. This study is measuring the feasibility of the Isomark Canary™ device. If the Canary does not detect a significant decrease in breath delta value in those subjects who subsequently get an infection, it will not be feasible to use it for this purpose.

Breath delta value will be collected to determine its relationship to infection, no health outcomes are being measured.

This study is designed to determine if the BDV of adult ICU patients is an early indicator of the onset of infection that may lead to sepsis.

The objectives of this study are: (1) to measure variation of BDV with time in adult ICU patients who agree to participate as research subjects; (2) to determine the magnitude of change of BDV in subjects who are subsequently diagnosed with severe infection and sepsis; (3) to define variation of BDV in adult trauma subjects who do not develop severe infection.

Inclusion Criteria:

1. age 18 years or older
2. critically ill patient admitted to trauma or surgical ICU
3. expected duration of hospital stay at least 120 hours (five days) from time of study enrollment
4. subject/LAR speaks a language of which the IRB has approved a consent form

Exclusion Criteria:

1. known infection at the time of enrollment per infection definitions in section 6.2
2. known use of systemic antibiotic, antimicrobial and/or antifungal therapy within the last 7 days (See Antibiotic Use section below)
3. prolonged antibiotic or antimicrobial use during the perioperative period (See Antibiotic Use section below)
4. currently active cancer, or receiving treatment for cancer (including but not limited to: radiation, chemotherapy, systemic orals, etc)
5. receiving high frequency ventilatory support
6. if not intubated, unable to cooperate with providing a breath sample
7. expected death within 24 hours of enrollment or lack of commitment to aggressive treatment by family/medical team (e.g., likely to withdraw life support measures within 24 hrs of screening)
8. female who is pregnant or lactating (negative serum or urine pregnancy test results within 48 hours of enrollment or to be performed during screening)
9. prisoner
10. known participation in an interventional research study within 30 days prior to enrollment (note: to be eligible, any interventional treatment must have ended at least 30 days ago)
11. Individuals who are directly affiliated with sponsor or study staff, or their immediate families. Immediate family is defined as spouse, domestic partner, parent, child, or sibling whether legally adopted or biological.
12. Any patient that is deemed unfit for study participation, per the Investigator's discretion.

10 days per subject, throughout enrollment period April 2015 to December 2017.