OBJECTIVE The objective of this study was to assess the value of prehospital measurement of lactate level in blood for diagnosis of seizures in cases of transient loss of consciousness. METHODS Between March 2018 and September 2019, prehospital lactate was measured with a point-of-care device by the emergency medical services in an area serving a population of 900 000. A total of 383 cases of transient loss of consciousness were identified and categorized as tonic-clonic seizure (TCS), other seizure, syncope, or other cause, according to the final diagnosis in the electronic medical records system. Receiver operating characteristic curve analyses were used to identify the optimal lactate cut-off. RESULTS A total of 383 cases were included (135 TCS, 42 other seizure, 163 syncope, and 43 other causes). The median lactate level in TCS was 7.0 mmol/L, compared to a median of 2.0 mmol/L in all other cases (P < .001). The area under the curve (AUC) of TCS vs nonepileptic causes was 0.87 (95% confidence interval [CI] 0.83-0.91). The optimal cut-off (Youden index, 67.8%) was 4.75 mmol/L, with 79% sensitivity (95% CI 71-85) and 89% specificity (95% CI 85-93) for TCS. SIGNIFICANCE Prehospital lactate can be a valuable tool for identifying seizures in transient loss of consciousness. For acceptable specificity, a higher cut-off than that previously demonstrated for hospital-based measurements must be used when values obtained close to the time of the event are interpreted.

中文翻译：

---

作为癫痫生物标志物的院前血乳酸水平：一项多中心观察性研究

目的 本研究的目的是评估院前检测血液中乳酸水平在短暂性意识丧失病例中诊断癫痫发作的价值。方法 2018 年 3 月至 2019 年 9 月，急诊医疗服务中心在 90 万人口的地区使用即时设备测量院前乳酸水平。共识别出 383 例短暂性意识丧失病例并将其归类为根据电子病历系统中的最终诊断，强直阵挛发作 (TCS)、其他癫痫发作、晕厥或其他原因。接受者操作特征曲线分析用于确定最佳乳酸临界值。结果 共纳入 383 例（135 例 TCS、42 例其他癫痫发作、163 例晕厥和 43 例其他原因）。TCS 的中位乳酸水平为 7.0 mmol/L，与所有其他情况下的中位数 2.0 mmol/L 相比（P < .001）。TCS 与非癫痫原因的曲线下面积 (AUC) 为 0.87（95% 置信区间 [CI] 0.83-0.91）。TCS 的最佳临界值（约登指数，67.8%）为 4.75 mmol/L，敏感性为 79%（95% CI 71-85），特异性为 89%（95% CI 85-93）。意义 院前乳酸可以成为识别短暂性意识丧失癫痫发作的宝贵工具。为了获得可接受的特异性，当解释接近事件发生时间获得的值时，必须使用比先前为基于医院的测量所证明的更高的截止值。75 mmol/L，TCS 的敏感性为 79% (95% CI 71-85)，特异性为 89% (95% CI 85-93)。意义 院前乳酸可以成为识别短暂性意识丧失癫痫发作的宝贵工具。为了获得可接受的特异性，当解释接近事件发生时间获得的值时，必须使用比先前为基于医院的测量所证明的更高的截止值。75 mmol/L，TCS 的敏感性为 79% (95% CI 71-85)，特异性为 89% (95% CI 85-93)。意义 院前乳酸可以成为识别短暂性意识丧失癫痫发作的宝贵工具。为了获得可接受的特异性，当解释接近事件发生时间获得的值时，必须使用比先前为基于医院的测量所证明的更高的截止值。