Relationship between End-Tidal CO(2) (ETCO(2)) and Lactate and their Role in Predicting Hospital Mortality in Critically Ill Trauma Patients; A Cohort Study

OBJECTIVE: To investigate the relationship between end-tidal CO(2) (ETCO(2)) and serum lactate and their predictive role in hospital mortality of intubated multiple trauma patients. METHODS: In a cohort study, intubated multiple trauma patients who referred to the emergency department for two years were enrolled. After orotracheal intubation using Rapid Sequence Intubation (RSI) method, ETCO2 was immediately measured by capnography. Blood samples for serum lactate measurements were sent to the laboratory, immediately after intubation. Data collection was done using the questionnaire, and the patients were followed using their medical records. RESULTS: Totally, 250 patients were included with hospital mortality of 14.8% (n=37). Using Pearson correlation, an inverse relationship was noticed between serum lactate and ETCO2, immediately (p<0.0001, r=-0.65). In adjusted multivariate analysis, three variables including heart rate (HR), serum lactate and ETCO2 showed a significant relationship with hospital mortality, respectively (p=0.007, p=0.009, p=0.023, respectively). Receiver operating characteristic curve illustrated an area under the curve (AUC) of 0.93, 0.96, and 0.97 for HR, lactate, and ETCO2, respectively. CONCLUSION: ETCO(2) post-intubation and serum lactate may be considered as prognostic factors for intubated multiple trauma patients referring to the emergency department, which can give the clinician an important clue in early prediction of the hospital mortality.