Relative hyperlactatemia and hospital mortality in critically ill patients: A retrospective multi-centre study

Australian and New Zealand Intensive Care-Research Centre, School of Public Health and Preventive Medicine, Monash University, Alfred Hospital Campus, 75 Commercial Road, Prahran, VIC 31821, Australia.
Critical care (London, England) (Impact Factor: 4.48). 02/2010; 14(1):R25. DOI: 10.1186/cc8888
Source: PubMed


Higher lactate concentrations within the normal reference range (relative hyperlactatemia) are not considered clinically significant. We tested the hypothesis that relative hyperlactatemia is independently associated with an increased risk of hospital death.
This observational study examined a prospectively obtained intensive care database of 7,155 consecutive critically ill patients admitted to the Intensive Care Units (ICUs) of four Australian university hospitals. We assessed the relationship between ICU admission lactate, maximal lactate and time-weighted lactate levels and hospital outcome in all patients and also in those patients whose lactate concentrations (admission n = 3,964, maximal n = 2,511, and time-weighted n = 4,584) were under 2 mmol.L-1 (i.e. relative hyperlactatemia).
We obtained 172,723 lactate measurements. Higher admission and time-weightedlactate concentration within the reference range was independently associated with increased hospital mortality (admission odds ratio (OR) 2.1, 95% confidence interval (CI) 1.3 to 3.5, P = 0.01; time-weighted OR 3.7, 95% CI 1.9 to 7.00, P < 0.0001). This significant association was first detectable at lactate concentrations > 0.75 mmol.L-1. Furthermore, in patients whose lactate ever exceeded 2 mmol.L-1, higher time-weighted lactate remained strongly associated with higher hospital mortality (OR 4.8, 95% CI 1.8 to 12.4, P < 0.001).
In critically ill patients, relative hyperlactataemia is independently associated with increased hospital mortality. Blood lactate concentrations > 0.75 mmol.L-1 can be used by clinicians to identify patients at higher risk of death. The current reference range for lactate in the critically ill may need to be re-assessed.

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    • "We used a single venous sample; the combination of single and venous as opposed to arterial and serial makes it logistically easier in low-resourced settings. Several studies have demonstrated the predictive value of a single venous sample [[16]–[18]]. We also found that the injured were mostly male with a 4:1 ratio similar to previous studies [[4],[19]–[21]] and were youthful (median age 28 years) comparable to previous studies [[22]–[24]]. "
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    ABSTRACT: Background Trauma is the leading cause of death in the developed world. Accurate assessment of severity of injuries is critical in informing treatment choices. Current models of assessing severity of injury are not without limitations. The objective of this study therefore was to determine the diagnostic accuracy of serum lactate assays in assessing injury severity and prediction of early outcomes among trauma patients. Methods This was a cross-sectional analytical study. Consecutive series of all eligible patients had a single venous blood sample drawn for lactate assay analysis (index test) and a concurrent Kampala Trauma Score (KTS) II value determination (reference test). Admitted patients were followed up to assess early outcomes (length of hospital stay and mortality). Results Out of the 502 trauma patients recruited, 108 (22%) were severely injured, 394 (78%) had non-severe injuries, and 183 were admitted. There was a significant difference between median (interquartile range (IQR)) lactate levels among the severely injured (4.3 (2.6, 6.6)) and the non-severely injured (2.4 (1.6, 3.5), p < 0.001). After a 72-h follow-up of the admitted patients, 102 (56%) were discharged, 61 (33%) remained in the hospital, 3 (2%) remained in the ICU, and 17 (3%) had died. The area under the receiver operator characteristic (ROC) curve was 0.75 for injury severity. Serum lactate ≥2.0 mmol/l had a hazard ratio of 1.10 (p < 0.001) for emergency department disposition, 4.33 (p = 0.06) for the 72-h non-discharge disposition, and 1.19 (p < 0.001) for 72-h mortality. Serum lactate ≥2.0 mmol/l at admission was useful in discriminating severe from non-severe injuries with a sensitivity of 88%, specificity of 38%, PPV of 30%, and NPV of 92%. Conclusion Hyperlactatemia in an emergency trauma patient suggests a high probability of severe injury.
    Full-text · Article · Jul 2014 · International Journal of Emergency Medicine
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    • "Our findings were supported by Nguyen et al. who reported in a prospective observational study an 11% decrease in mortality for each 10% decrease in lactate clearance [16]. This was also confirmed by Nichol et al. 2010 in a retrospective multi-center study who studied the effect of relative hyperlactatemia on hospital mortality in critically ill patients [30]. Mixed central venous oxygen saturation is correlated to the central venous saturation and our data were found to be significantly different between both groups after 24 h. "
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    ABSTRACT: Introduction Severe community acquired pneumonia (SCAP) occurs in approximately 18–36% of all CAP and the mortality rate could be as high as 67% in patients with SCAP. Several studies have described a correlation between baseline lactate concentration and mortality of ICU patients. Aim of the work To follow lactate clearance after admission for 24 h which could be an indicator of outcome in severe community acquired pneumonia. Patients and methods Forty-six consecutively admitted adult patients were diagnosed as severe community acquired pneumonia. Lactate was measured at the time of admission (H0), reassessment of lactate level was done after 8 h and also another lactate measurement done after 24 h. In a trial to follow the guideline for management and to optimize oxygen delivery (DO2) and reach a ScvO2 ⩾ 70%, ScvO2 was measured through a central venous blood sample done at the same time with lactate. During the study resuscitation by inotropic medications and patient’s physiological parameters were measured routinely. All data needed to calculate the Acute Physiology and Chronic Health Evaluation (APACHE II) score were recorded. Results Most of patients in the current study were above the age of 60 years. Twenty-five patients had lactate clearance of more than 40%, those patients were included in group 1, whereas 21 had lactate clearance of 40% or less and they were included in group II. There was no significant difference in the age and sex distribution between both groups. Out of 21 patients included in group II, inotropic drugs were used in 8 patients (38%), whereas there was one patient only in group 1. The rate of intubation in addition to the mean APACHE II score and ICU length of stay was significantly higher in group II compared to group I. Over the first 24 h three readings for mixed venous oxygen were recorded and included in the analysis. The reading of mixed venous oxygen recorded after 24 h of ICU admission was significantly high in group 1. All indices of blood lactate clearance over the first 24 h were higher in group 1 compared to group II, however it was only significantly high after 24 h (p-value 0.01). Conclusion Our study suggests that lactate clearance could be used as a useful biomarker which is inexpensive and a reliable predictor of patient outcome in critically ill patients admitted to ICU with severe community-acquired pneumonia.
    Full-text · Article · Jun 2014
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    • "In our population sample, 36.2% of patients had a PVL ≥ 2 mmol/L and AL b2 mmol/L. A cut-off of 2 mmol/L has been reported in ED, intensive care unit, trauma, pre-hospital and pediatric populations as conferring an increased risk of mortality [23] [24] [25] [26] [28] [29] [30]. A lactate of 4 mmol/L has been reported as conferring a further increased risk of mortality in infection, sepsis, and shock [6] [31] [32] [33] [34] [35]. "
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    ABSTRACT: The evidence for prognostication using lactate is often based on arterial lactate (AL). Arterial sampling is painful and difficult, and carries risks. Studies comparing peripheral venous lactate (PVL) with AL showed little difference but predominantly included patients with normal lactate. The objective of this study was to measure agreement between PVL and AL in patients with elevated venous lactate. This is a retrospective cross-sectional study. Inclusion criteria: ED patients age ≥16, attending from October 2010 to June 2011 inclusive, with PVL ≥2.0mmol/L and AL taken within 1 hour. Exclusion criteria: intravenous fluid prior to or between initial venous and arterial sampling. Primary endpoint: agreement between PVL and AL defined as mean difference ±95% limits of agreement (LOA). The misclassification rate was assessed. N=232. VL median 3.50mmol/L, range 2.00 to 15.00mmol/L. AL median 2.45mmol/L, range 1.0 to 13.2mmol/L. The mean difference±SD between PVL and AL for all patients was 1.06±1.30mmol/L (95%LOA -1.53 to 3.66mmol/L). Using a cut-off of 2mmol/L and 4mmol/L, 36.2% and 17.9% of patients respectively were incorrectly classified as having elevated lactate. We report greater bias between VL and AL with broader LOA than previously documented. This may partly be due to the fact that we studied only patients with abnormal venous values, for whom close agreement would confer greatest clinical significance. The agreement between abnormal PVL and AL is poor and the high rate of misclassification may suggest that PVL is not a good substitute for AL if the venous lactate is abnormal.
    Full-text · Article · Mar 2014 · The American journal of emergency medicine
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