Our objective is to determine whether or not the presence of hemoperitoneum in trauma patients is associated with increased Carbon Monoxide (CO) formation, and to determine if elevated Carbon Monoxide levels are associated with cardiovascular depression, impaired platelet aggregation, and/or multiple organ failure.

Inclusion Criteria:

1. Hospitalized males 18 years of age or older,
2. Diagnosis of isolated blunt OR blunt and penetrating trauma,
3. Admitted or expecting to be admitted to the Intensive Care Unit,
4. On mechanical ventilation, and
5. Written informed consent obtained

Exclusion Criteria:

1. Female gender, (Females will be excluded from this study as the menstrual cycle and other estrogen variations are known to be associated with cyclic changes in CO production adding a potential confounder to the interpretations of our findings.)
2. Diagnosis of isolated penetrating trauma,
3. Acute hemothorax or pneumothorax,
4. Treatment with antiaggregants (ASA, clopidogrel, aggrenox or ticlopidine),
5. Enrollment in another research study,
6. Prisoners,
7. Inability to perform CO measurement within 96 hours after hospital admission.

patients in the ICU on a ventilator