Research Report

Background Overview

Traumatic Brain Injury (TBI) is one of the leading causes of permanent disability and death worldwide. These disorders are dynamic and evolving, involving progressive brain injury and pathophysiological changes accompanied by multi-system damage. The severity of TBI is typically assessed using the Glasgow Coma Scale (GCS), which was created by Teasdale and Jennett in 1974 and first included in the Advanced Trauma Life Support (ATLS) standards in 1980. The GCS is a simple, reliable, and easy-to-interpret scoring system used to monitor the level of consciousness in TBI patients in detail. Especially emergency medical services (EMS) have made it an important tool for the initial assessment of patients. However, there are certain limitations to the GCS in global assessments, and the current study aims to explore the potential and performance of GCS and lactate as clinical decision-making tools.

Research Source

This research paper was completed by five authors: Francisco Martin-Rodriguez, Ancor Sanz-Garcia, Raul Lopez-Izquierdo, Juan F. Delgado Benito, Francisco T. Martinez Fernandez, Santiago Otero de la Torre, and Carlos Del Pozo Vegas, who are affiliated with several higher education institutions and hospitals in Spain. The study was published in the August 2024 issue of the journal “Neurology”.

Research Methods

Study Design and Subjects

This was a prospective, multicenter, EMS-delivered derivation-validation cohort study, conducted from November 1, 2019, to July 31, 2022, at five tertiary hospitals in Spain. The study subjects were adult callers with acute TBI. Exclusion criteria included minors, pregnant women, trauma patients without TBI, delayed presentation patients, patients discharged at the scene, patients experiencing cardiac arrest, and patients from whom blood samples could not be obtained. The primary outcomes were all-cause 2-day in-hospital mortality and 90-day mortality.

Study Process

The study recruited a total of 509 patients, with an average age of 58 years (interquartile range: 43-75), including 167 females (32.8%). The study design included two cohorts, one derivation cohort and one validation cohort. All patients had lactate and glucose levels recorded at the EMS site, along with monitoring of vital signs.

Main experimental and data collection processes included: 1. Epidemiological data: gender, age, timeline, workforce shift, and intervention zone. 2. Injury details: mechanism, associated injuries, penetrating trauma. 3. On-site vital signs: respiratory rate, oxygen saturation, systolic blood pressure, heart rate, and GCS score. 4. Point-of-care testing (POCT): including lactate and glucose concentrations. 5. Associated machines and algorithms: Statistical models such as the area under the ROC curve (AUC), calibration curve analysis, etc.

Data Analysis

Statistical analysis was conducted using R software (version 4.2.2). Data characteristics included using percentages for categorical variables, and means and standard deviations for continuous variables. The effectiveness of lactate as a predictor of short-term mortality was evaluated using multiple regression models, calibration curves, and various statistical evaluation metrics such as Sensitivity (Sen), Specificity (Sp), Positive Predictive Value (PPV), and Negative Predictive Value (NPV).

Main Research Results

A total of 509 patients were included in the study, with key findings including:

1. 2-day and 90-day in-hospital mortality:
   • The 2-day in-hospital mortality for patients with moderate to mild TBI (GCS ≥ 9 points) was 2.2%, while it was 44.7% for severe TBI patients (GCS ≤ 8 points).
   • High lactate levels were significantly associated with increased short-term mortality.
2. Lactate predictive ability:
   • The predictive ability of lactate concentration in the validation cohort had an AUC of 0.874 (95% CI 0.805–0.942).
   • For patients with GCS ≥ 9 points, the predictive ability of lactate concentration was stronger, with an AUC of 0.925 (95% CI 0.808–1.000), and a negative predictive value of 99.09 (95% CI 98.55–99.64).
3. Clinical significance:
   • Measuring lactate levels can identify high-risk TBI patients earlier, especially those with higher GCS scores. This has important clinical implications for optimizing patient transfer and treatment strategies.

Summary and Conclusion

The study demonstrates significant benefits in using lactate testing among all TBI patients, particularly those with a GCS score ≥ 9 points. The routine inclusion of lactate testing has the potential to reduce mortality and deterioration rates by rapidly and better identifying high-risk patients. This study emphasizes that the routine use of POCT lactate levels can help healthcare services better identify potential neurocritical patients in the pre-hospital phase, optimizing decision-making processes and improving patient outcomes.

Research Highlights

Significant findings of the study include: 1. Effectiveness of lactate as an early predictor: Lactate levels showed significant performance in predicting short-term mortality in TBI patients, especially in moderate to mild TBI patients. 2. Supplement to GCS scores: Although GCS scores are widely used in clinical practice, lactate levels provide additional predictive information that helps identify high-risk patients. 3. Improvement in on-site medical services: Rapid on-site testing of lactate levels can significantly optimize EMS response strategies, further enhancing early intervention outcomes for TBI patients.

This study offers new perspectives for the early prediction and intervention in traumatic brain injury patients, showcasing the great potential of lactate as a biomarker in clinical practice.