Original Contribution
Initial hyperlactatemia in the ED is associated with poor outcome in patients with ischemic stroke

https://doi.org/10.1016/j.ajem.2011.12.019Get rights and content

Abstract

Background

Hyperlactatemia may be associated with poor outcome in patients with ischemic stroke because it reflects a state of tissue perfusion. This study aims to know whether initial hyperlactatemia in the emergency department (ED) is associated with poor outcome in patients with ischemic stroke.

Methods

A retrospective observational study was performed in an urban tertiary hospital ED. Patients with an admission diagnosis of ischemic stroke were consecutively enrolled between April 1, 2010, and March 31, 2011. Lactate and glucose levels were obtained at the time of presentation to the ED, whereas the National Institutes of Health Stroke Scale score was assessed at the time of admission. Poor outcome was defined as a modified Rankin scale score greater than or equal to 2 at 3 months. The survival status at 3 months was also obtained. Hyperlactatemia was defined by lactate levels greater than 2 mmol/L.

Results

A total of 292 patients were enrolled. At 3 months after stroke, 183 (62.7%) were considered to have poor outcomes, whereas 16 (5.5%) had died. Seventy (24.0%) had initial hyperlactatemia. Multivariable logistic regression analysis showed that hyperlactatemia was independently associated with a higher risk of poor outcome at 3 months (adjusted odd ratio, 2.15; 95% confidence interval, 1.06-4.37; P = .035) and a trend to death at 3 months (adjusted odd ratio, 4.31; 95% confidence interval, 0.91-20.56; P = .066).

Conclusions

Among patients with ischemic stroke, initial hyperlactatemia represents an independent risk factor for poor outcome after controlling for stroke severity, risk factors, initial glucose level, and interval from onset of stroke symptoms to ED arrival.

Introduction

In the United States, approximately 8% of ischemic strokes result in death [1]. Accordingly, it is important to identify accurate predictors of outcome after ischemic stroke. Although a clinical prognostic scoring model has been designed and validated [2], there are still research efforts to identify prognostic factors among laboratory markers related to inflammation, hemostasis, neuronal or glial injury, and cardiac dysfunction [3].

Hyperlactatemia is considered a marker of the metabolic stress response and is associated with increased mortality in critically ill patients [4], [5], [6]. In several previous studies using magnetic resonance spectrometry and microdialysis, lactate has been shown to accumulate in ischemic brain lesions among patients with acute stroke [7], [8], [9]. Recently, Brouns et al [10] demonstrated that the cerebrospinal fluid (CSF) lactate level is a reliable marker for metabolic crisis in acute ischemic stroke or transient ischemic attack and is associated with long-term outcomes. Although Brouns et al failed to show an association between blood lactate level and poor outcome, their study lacked the power to demonstrate negative conclusions, given the heterogeneity of the study sample.

As such, in the present study, we aimed to determine whether hyperlactatemia is associated with poor outcome and/or death in patients with ischemic stroke.

Section snippets

Study design

This retrospective observational study was approved by the institutional review board of the host hospital, and a waiver for informed consent was obtained. The study was conducted at a 1000-bed urban academic tertiary care hospital with an annual emergency department (ED) census of 35 000. Patients were initially evaluated by ED physicians and then by neurology attending physicians.

Between April 1, 2010, and March 31, 2011, all consecutive patients admitted via the ED with an admission

Baseline characteristics

Data from baseline demographics, risk factors, and stroke diagnosis are presented in Table 1. The mean subject age was 68.6 ± 12.2 years, with men comprising a larger proportion of the study cohort (58.2%). The mean time from stroke onset to ED arrival was 11.8 ± 17.3 hours, whereas the mean initial NIHSS score was 5.9 ± 6.1. In total, 64 patients (21.9%) received intravenous thrombolysis, and transfemoral cerebral angiography (TFCA) was performed in 67 patients (22.9%). Initial lactate levels

Discussion

Our results demonstrate that after adjusting for potential confounders, patients with lactate levels greater than 2 mmol/L at the time of initial presentation to the ED have an increased risk of poor outcome at 3 months. To our knowledge, this is the first report to detect an association between hyperlactatemia and poor outcome in patients with ischemic stroke.

Lactate is a known by-product of anaerobic metabolism and is elevated in hypoperfusion states. Specifically, lactate accumulates when

Limitations

The results of this study must be interpreted in the context of the study limitations. This study represents a retrospective observational study performed in a single center without any controls. Although we adjusted for known confounders, we could not completely exclude the residual effect of confounding. Moreover, the prestroke functional status of enrolled patients was not available. We also did not analyze the lacunar stroke subgroup. Mortality cases were sparse; the resulting regression

Conclusion

In patients with ischemic stroke, initial hyperlactatemia represents an independent risk factor for poor outcome at 3 months, after controlling for stroke severity, risk factors, and interval from onset of stroke symptoms to ED arrival. Hyperlactatemia showed a trend of death at 3 months.

Acknowledgment

We offer special thanks to Yujin Jo for assistance with data collection.

References (39)

  • O. Cerović et al.

    Relationship between injury severity and lactate levels in severely injured patients

    Intensive Care Med

    (2003)
  • H.B. Nguyen et al.

    Early lactate clearance is associated with improved outcome in severe sepsis and septic shock

    Crit Care Med

    (2004)
  • F. Nicoli et al.

    Metabolic counterpart of decreased apparent diffusion coefficient during hyperacute ischemic stroke: a brain proton magnetic resonance spectroscopic imaging study

    Stroke

    (2003)
  • G.D. Graham et al.

    Spectroscopic assessment of alterations in macromolecule and small-molecule metabolites in human brain after stroke

    Stroke

    (2001)
  • S. Schneweis et al.

    Predictive value of neurochemical monitoring in large middle cerebral artery infarction

    Stroke

    (2001)
  • European Stroke Organisation (ESO) Executive Committee: ESO Writing Committee

    Guidelines for management of ischaemic stroke and transient ischaemic attack 2008

    Cerebrovasc Dis

    (2008)
  • H.P. Adams et al.

    Classification of subtype of acute ischemic stroke. Definitions for use in a multicenter clinical trial. Toast. Trial of org 10172 in acute stroke treatment

    Stroke

    (1993)
  • T. Brott et al.

    Measurements of acute cerebral infarction: a clinical examination scale

    Stroke

    (1989)
  • J.C. Van Swieten et al.

    Interobserver agreement for the assessment of handicap in stroke patients

    Stroke

    (1988)
  • Cited by (0)

    View full text