Background: Penetrating trauma patients in shock often require urgent operative intervention. Studies have demonstrated that variables obtained in the emergency department, such as lactate levels, can help the physician determine the presence of hemorrhagic shock, leading to more rapid intervention and improve prognosis in trauma patients. The purpose of the study is to determine if end-tidal (ET) CO2 correlates with serum lactate levels, a measure of tissue hypoxia and subsequently shock, in penetrating trauma patients. Secondarily, we sought to determine whether ET CO2 could be used to determine the patient's odds of requiring operative intervention.
Methods: A prospective observational cohort study was undertaken at an urban Level 1 trauma center. Baseline ET CO2 from nasal cannula and serum lactate level were recorded in all patients in whom the trauma team was activated. Outcomes defined were whether operative intervention was needed. Pearson correlation (R), correlation coefficient (r(2)), and odds ratio were calculated.
Results: One hundred five patients were enrolled. Pearson correlations and coefficients calculated for serum lactate level to ET CO2 were R = -0.86 (r(2) = 0.74, p < 0.0001). Of patients requiring operative intervention, 81.97% had abnormally low ET CO2 and 54.1% had abnormally high serum lactate levels. Odds ratios of patients needing an emergent operation with abnormally low ET CO2 was 20.4 (95% confidence interval, 7.47-55.96) and with abnormally high serum lactate levels was 4 (95% confidence interval, 1.68-5.93).
Conclusion: ET CO2 has a strong inverse correlation to serum lactate levels. Abnormally low ET CO2 values were associated with greater increased odds compared with serum lactate levels of penetrating trauma patients requiring operative intervention.
Level of evidence: Prognostic/diagnostic study, level I.