Updates in ED Management of Trauma Patients
Rapid and accurate triage is imperative to optimizing outcomes for trauma patients. Primary and secondary surveys as well as information about mechanism and circumstances of injury provide important prognostic information. Additionally, early lactic acid levels have been shown to predict outcomes for trauma patients, including risk of mortality. Two recent studies now expand on this with further identification of prognostic factors in trauma patients.
Caputo, et al., explored the use of end tidal carbon dioxide (ETCO2) measurements as a surrogate for lactate levels and predictor of need for surgery in penetrating trauma patients. In a prospective cohort study, they enrolled 105 patients with penetrating trauma at a single urban Level-I trauma center. Subjects underwent measurement of ETCO2 by nasal cannula and arterial serum lactate on arrival to the hospital. Inclusion criteria were any penetrating trauma patient for whom the trauma team was activated (criteria include blood pressure in adults less than 90mmHg at any time, gunshot wounds to the head, chest or abdomen, GCS less than 8, respiratory compromise, or emergency physician discretion). Exclusion criteria were loss of vital signs before reaching the trauma bay, intubation prior to arrival, or need for surgical airway support. The primary end point was determination of correlation between ETCO2 level and serum lactate level. The secondary end point was determination of correlation between ETCO2 level and need for surgical intervention.
Physiologically, the metabolic acidosis caused by elevated lactate levels should cause an accompanying decrease in blood and ETCO2 levels. For this study, an elevated serum lactate level was considered to be greater than 4.0, and a depressed ETCO2 was considered to be less than 35mmHg. Of the 105 subjects, 58 had a depressed ETCO2 and 43 had an elevated serum lactate. The authors found a strong inverse correlation between measured ETCO2 and serum lactate (R=-0.86, p=0.74; 0.63-0.81 for 95% CI, p=0.0001). Interestingly, they found no correlation between either serum lactate or ETCO2 with systolic blood pressure on hospital arrival. Of the 105 subjects, 61 required operative intervention, and of those 54% had elevated serum lactate and 82% had depressed ETCO2. The odds ratio of requiring surgical intervention for those having depressed ETCO2 was 20.4 (7.47-55.96 for 95% CI). For those with elevated serum lactate or systolic hypotension they were 4 (1.68-9.53 for 95% CI) and 3.01 (0.32-27 for 95% CI) respectively. The sensitivity and specificity of depressed ETCO2 for predicting need for surgery were 0.82 (0.69-0.9 for 95% CI) and 0.82 (0.66-0.91 for 95% CI) respectively.
This study suggests a role for end tidal CO2 measurement by nasal cannula as a fast and easily-obtainable surrogate for serum lactate level in penetrating trauma patients. Additionally, the ETCO2 measurement has a strong predictive value for patients requiring surgical intervention. Limitations of this study include exclusion of blunt trauma patients, restriction to a single center, and the possibility of breath-to-breath measurement error intrinsic to nasal cannula capnography.
Régnier, et al., expand on the use of serum lactate as a marker of outcome in trauma patients by exploring trends in lactate clearance. In an observational study, they measured serum lactate on hospital arrival, and again at 2 and 4 hour time intervals for 586 patients of blunt and penetrating trauma at a single level I trauma center. Specific inclusion and exclusion criteria were not laid out, but of the 730 patients in the trauma center during the study dates, 586 had lactic acid levels drawn and were included in the study. The primary end point was 30-day survival. Secondary end points included death within 48 hours, ICU stay longer than two days, massive hemorrhage (requiring six or more units of packed red blood cells within 24 hours or causing death), and the need for emergent procedures (surgery, embolization, transfusion, or thoracic drainage). For each endpoint, the authors generated receiveroperating characteristic (ROC) curves to determine the predictive value of lactate clearance. End points were examined both for the study population as a whole, and for the following two subgroups: patients with high (>5mM/L) initial lactate, and normotensive (SBP>90) patients.
The strongest conclusions of this study were made in the subgroup of patients with initially elevated serum lactate. In this group, initial blood lactate, lactate clearance, and Trauma Related Injury Severity Score (TRISS) were each independent predictors of mortality (area under ROC curve 0.77, 0.60-0.87 for 95% CI; 0.67, 0.51-0.78 for 95% CI; and 0.90, 0.79-0.95 for 95% CI, respectively). The authors note, though, that a predictive model incorporating lactate clearance with TRISS did not provide additional information when compared with using TRISS alone (area under ROC curve 0.92 in both cases).
This study demonstrates that lactic acid clearance over 4 hours can add prognostic information in the evaluation of trauma patients. Limitations of this study include restriction to a single center, and inclusion of only adult patients. Additionally, lactate clearance may be impaired by serious liver injuries. While the authors acknowledge this and note that 68 patients (12%) in their population had severe hepatic contusion, these patients were not excluded from the study or analyzed separately.
Trauma Biomarkers: Monitoring of End Tidal CO2 and Lactate Clearance
Rapid and accurate triage is imperative to optimizing outcomes for trauma patients. Primary and secondary surveys as well as information about mechanism and circumstances of injury provide important prognostic information. Additionally, early lactic acid levels have been shown to predict outcomes for trauma patients, including risk of mortality. Two recent studies now expand on this with further identification of prognostic factors in trauma patients.
Caputo ND, Fraser RM, Paliga A, Matario J, Kanter M, Hosford K, Madlinger R. Nasal cannula end-tidal CO2 correlates with serum lactate levels and odds of operative intervention in penetrating trauma patients: A prospective cohort study. J Trauma Acute Care Surg; 73 (5), 1202-7.
Caputo, et al., explored the use of end tidal carbon dioxide (ETCO2) measurements as a surrogate for lactate levels and predictor of need for surgery in penetrating trauma patients. In a prospective cohort study, they enrolled 105 patients with penetrating trauma at a single urban Level-I trauma center. Subjects underwent measurement of ETCO2 by nasal cannula and arterial serum lactate on arrival to the hospital. Inclusion criteria were any penetrating trauma patient for whom the trauma team was activated (criteria include blood pressure in adults less than 90mmHg at any time, gunshot wounds to the head, chest or abdomen, GCS less than 8, respiratory compromise, or emergency physician discretion). Exclusion criteria were loss of vital signs before reaching the trauma bay, intubation prior to arrival, or need for surgical airway support. The primary end point was determination of correlation between ETCO2 level and serum lactate level. The secondary end point was determination of correlation between ETCO2 level and need for surgical intervention.
Physiologically, the metabolic acidosis caused by elevated lactate levels should cause an accompanying decrease in blood and ETCO2 levels. For this study, an elevated serum lactate level was considered to be greater than 4.0, and a depressed ETCO2 was considered to be less than 35mmHg. Of the 105 subjects, 58 had a depressed ETCO2 and 43 had an elevated serum lactate. The authors found a strong inverse correlation between measured ETCO2 and serum lactate (R=-0.86, p=0.74; 0.63-0.81 for 95% CI, p=0.0001). Interestingly, they found no correlation between either serum lactate or ETCO2 with systolic blood pressure on hospital arrival. Of the 105 subjects, 61 required operative intervention, and of those 54% had elevated serum lactate and 82% had depressed ETCO2. The odds ratio of requiring surgical intervention for those having depressed ETCO2 was 20.4 (7.47-55.96 for 95% CI). For those with elevated serum lactate or systolic hypotension they were 4 (1.68-9.53 for 95% CI) and 3.01 (0.32-27 for 95% CI) respectively. The sensitivity and specificity of depressed ETCO2 for predicting need for surgery were 0.82 (0.69-0.9 for 95% CI) and 0.82 (0.66-0.91 for 95% CI) respectively.
This study suggests a role for end tidal CO2 measurement by nasal cannula as a fast and easily-obtainable surrogate for serum lactate level in penetrating trauma patients. Additionally, the ETCO2 measurement has a strong predictive value for patients requiring surgical intervention. Limitations of this study include exclusion of blunt trauma patients, restriction to a single center, and the possibility of breath-to-breath measurement error intrinsic to nasal cannula capnography.
Régnier M-A, Raux M, Le Manach Y, Asencio Y, Gaillard J, Devilliers C, Langeron O, Riou B. Prognostic significance of blood lactate and lactate clearance in trauma patients. Anesthesiology 2012; 117(6), 1276-88.
Régnier, et al., expand on the use of serum lactate as a marker of outcome in trauma patients by exploring trends in lactate clearance. In an observational study, they measured serum lactate on hospital arrival, and again at 2 and 4 hour time intervals for 586 patients of blunt and penetrating trauma at a single level I trauma center. Specific inclusion and exclusion criteria were not laid out, but of the 730 patients in the trauma center during the study dates, 586 had lactic acid levels drawn and were included in the study. The primary end point was 30-day survival. Secondary end points included death within 48 hours, ICU stay longer than two days, massive hemorrhage (requiring six or more units of packed red blood cells within 24 hours or causing death), and the need for emergent procedures (surgery, embolization, transfusion, or thoracic drainage). For each endpoint, the authors generated receiveroperating characteristic (ROC) curves to determine the predictive value of lactate clearance. End points were examined both for the study population as a whole, and for the following two subgroups: patients with high (>5mM/L) initial lactate, and normotensive (SBP>90) patients.
The strongest conclusions of this study were made in the subgroup of patients with initially elevated serum lactate. In this group, initial blood lactate, lactate clearance, and Trauma Related Injury Severity Score (TRISS) were each independent predictors of mortality (area under ROC curve 0.77, 0.60-0.87 for 95% CI; 0.67, 0.51-0.78 for 95% CI; and 0.90, 0.79-0.95 for 95% CI, respectively). The authors note, though, that a predictive model incorporating lactate clearance with TRISS did not provide additional information when compared with using TRISS alone (area under ROC curve 0.92 in both cases).
This study demonstrates that lactic acid clearance over 4 hours can add prognostic information in the evaluation of trauma patients. Limitations of this study include restriction to a single center, and inclusion of only adult patients. Additionally, lactate clearance may be impaired by serious liver injuries. While the authors acknowledge this and note that 68 patients (12%) in their population had severe hepatic contusion, these patients were not excluded from the study or analyzed separately.