Original ContributionArterial lactate improves the prognostic performance of severity score systems in septic patients in the ED☆,☆☆
Introduction
The incidence of sepsis, especially severe sepsis and septic shock, has increased during the previous decades and has resulted in an increased number of deaths [1], [2], [3], [4]. Early recognition, accurate risk classification, and timely intervention are crucial to improve the outcome [5], [6], [7]. The risk classification tools mainly include illness severity score systems and biomarkers. The most widely used severity score systems in septic patients include Acute Physiology and Chronic Health Evaluation (APACHE) II, Sequential Organ Failure Assessment (SOFA), and Mortality in Emergency Department Sepsis (MEDS) scores [8], [9], [10]. Acute Physiology and Chronic Health Evaluation II and SOFA derive from critically ill patients admitted to the intensive care unit (ICU) and are identified as effective for prognosis in septic patients [11], [12]. The MEDS score is the only system specifically created for septic patients in the emergency department (ED) and has shown superior prognostic stratification ability in previous studies [13], [14], [15]. Several studies have shown that combining biomarkers and illness severity score systems improves the prognostic value of both, but few studies have attempted to add a biomarker to a score system [16], [17], [18], [19].
Impaired tissue oxygenation is a hallmark of septic shock. Cellular dysfunction causes metabolism to shift to the anaerobic pathway and leads to an increase in lactate production; meanwhile, sepsis impairs lactate clearance and results in increased lactate levels. But many patients have unapparent shock. The elevation of lactate can occur before changes in vital signs. Blood lactate has been widely demonstrated as a marker of tissue hypoxia as well as a predictor for overall death among critically ill patients [20], [21], [22], [23], [24]. Several studies show that high lactate levels in septic shock are related to poor outcomes [25], [26], [27], [28]. Even intermediate initial serum lactate was associated with mortality independent of clinically apparent organ dysfunction and shock in severe sepsis patients admitted to the ED [25]. Previous studies demonstrated that lactate is a robust predictor of mortality in septic patients admitted to the ED or ICU. The most recent guideline for severe sepsis and septic shock indicates that lactate greater than 4 mmol/L mandates prompt resuscitation [29]. Lactate is not novel but is one of the important prognostic biomarkers of septic patients. Consideration of the importance of lactate, the predisposition, insult, response, and organ dysfunction (PIRO) system contains it [30]. However, no study has yet investigated how to add lactate to the widely used score systems, such as APACHE II, SOFA, and MEDS.
The present study aimed to evaluate the prognostic performance of lactate in septic patients in the ED and to investigate how to add lactate to the traditional score systems.
Section snippets
Study design and setting
This was a single-center, prospective, observational clinical study conducted at Beijing Chao-Yang Hospital, an urban teaching hospital of Capital Medical University with 250 000 annual ED visitors. The study was approved by the Beijing Chao-Yang Hospital Ethics Committee, and written informed consent was obtained from patients or their relatives.
The enrollment criteria were age ≥ 18 years and fulfillment of the sepsis criteria as defined by the International Sepsis Definitions Conference [31].
Characteristics of the study cohort
Eight hundred thirty-seven consecutive septic patients were screened from November 2011 to October 2012. We excluded 153 patients with noninfectious disease and 4 patients with incomplete data and thus included 680 septic patients in the study. Arterial lactate level was measured within 1 hour of ED arrival in every patient. All patients were followed-up to 28-day after enrollment, 238 patients were followed up by telephone, and others by medical record. The characteristics of the study cohort
Discussion
The present study demonstrated that lactate is a predictor of mortality independently of commonly used severity score systems, and it improved the prognostic performance of the score systems. The additional important result of the study was that it found a feasible way to add the lactate to the score systems.
Lactate has been evaluated as a prognostic tool in infectious patients and has been found to predict mortality [32], [33], [34], [35]. The prognostic value of lactate was independent of
Conclusions
Lactate is a prognostic predictor in septic patients in ED, and it improves the performance of APACHE II, SOFA, and MEDS scores in predicting mortality. A modified MEDS was defined as MEDS plus lactate. The prognostic and risk-stratified performance of modified MEDS was superior to MEDS.
Acknowledgments
We thank Bo Liu, Qin Yin, and Yun-Zhou Zhao for their excellent assistance. We also thank both the ED and biochemistry laboratory staff for their helpful contributions to the study.
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2015, American Journal of Emergency MedicineCitation Excerpt :These findings imply that the implementation of serum lactate in risk scoring systems may improve the prognostic performance for patients with sepsis. Actually, Chen et al [26] recently reported that the modified Acute Physiology and Chronic Health Evaluation (APACHE) II, Sequential Organ Failure Assessment (SOFA), and Mortality in Emergency Department Sepsis (MEDS) by arterial lactate level showed better prognostic value than original score systems in patients with sepsis in the ED. Because the respiratory tract is a most common site for the origin of sepsis [17], the serum lactate level is supposed to be a prognostic factor in CAP.
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2015, Journal of Emergency NursingCitation Excerpt :Although trends in response to treatment should be carefully monitored, specific target goals for heart rate are difficult to define and may not be useful. Elevation of serum or blood lactate (> 4 mmol/L) may help identify the severity of shock at presentation.7 Although evidence is limited in children, reduction in serum or blood lactate levels have been associated with improved survival in adults with shock.8–10