Comparison of lactate values obtained from different sites and their clinical significance in patients with severe sepsis

The agreement between arterial and venous lactate in patients with sepsis

BACKGROUND

Arterial sampling, which is the gold standard for measuring lactate levels in sepsis, is more painful, requires experience and is associated with a higher incidence of morbidity, when compared with venous sampling. This study attempted to measure the correlation and agreement between arterial and peripheral venous (PV) lactate and between arterial and central venous (CV) lactate, with the objective to test interchangeability of the two and possibly support the use of venous lactate levels in resuscitating patients with sepsis.

METHODS

Eighty-seven patients admitted to the critical care unit of our hospital with the diagnosis of sepsis or septic shock were included in the study after taking informed consent. The arterial, PV and CV samples were taken within the first 24 hours following admission and within 10 minutes of each other. Lactate levels, CV oxygen saturation (ScvO₂ ) and base excess of each sample type were reported within 15 minutes of collection. Patients were followed up for a period of 28 days to record the need for organ support (newly diagnosed renal failure, need for renal replacement therapy [RRT], liver failure, coagulopathy and need for ventilation) and mortality.

RESULTS

Pearson correlation for arterial versus PV lactate was 0.76 and for arterial versus CV lactate was 0.992. The mean difference between arterial and PV lactate was found to be -0.30 (95% confidence interval [CI], -0.38 to -0.21). The upper and lower limits of agreement were 0.51 and -1.10, respectively. Mean difference between arterial and CV lactate was found to be -0.13 (95% CI, -0.21 to -0.05). Upper and lower limits of agreement were 0.63 and -0.89, respectively.

CONCLUSION

Our study demonstrates a high level of agreement in the lactate levels as measured on venous samples and arterial samples. Venous lactate levels are reliable in resuscitation of patients with sepsis.

Combined score based on arterial lactate, aspartate transaminase and prolonged capillary refill time is a useful diagnostic criterion for identifying severe dengue

BACKGROUND

Taking into consideration, the variable performance of WHO's dengue case definition and the magnitude of epidemics in India, a score based on clinical and laboratory parameters is required for the early identification of severe dengue.

METHODS

A retrospective observational study of children (aged ≤12 y) presenting with dengue, defined as per the WHO 2009 classification and NS1 antigen/IgM ELISA positivity, was conducted at a tertiary care hospital from 2013 to 2015. Clinical laboratory parameters were compared between severe/non-severe dengue using univariate and multivariate analysis. Areas under receiver operating characteristic curves (AUROCs), sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) were obtained for independent and composite markers.

RESULTS

Of 135 dengue patients, 46 (34.1%) had non-severe dengue and 89 (65.9%) had severe dengue. Logistic regression determined prolonged capillary refill time (CRT), lactate ≥2.9 mmol/L and serum aspartate transaminase (AST) ≥135 IU/L as predictive for severe dengue. AUROCs of lactate, AST and combined score incorporating AST, lactate and prolonged CRT for identifying severity were 7.55, 7.23 and 8.5, respectively. The combined score cut-off ≥1 had 87.6% sensitivity, 65.2% specificity, 83% PPV and 73.2% NPV. The combined score cut-off ≥3 had 100% specificity and 100% PPV.  However, AST >135 IU/L and lactate >2.9 mmol/L together had 97.8% specificity and 97.1% PPV for identifying severity.

CONCLUSIONS

The presence of either 'prolonged capillary refill time with one deranged biochemical parameter' or 'both deranged biochemical parameters' is nearly 100% specific for severity of dengue.

Demystifying Lactate in the Emergency Department

The role of lactic acid and its conjugate base, lactate, has evolved during the past decade in the care of patients in the emergency department (ED). A recent national sepsis quality measure has led to increased use of serum lactate in the ED, but many causes for hyperlactatemia exist outside of sepsis. We provide a review of the biology of lactate production and metabolism, the many causes of hyperlactatemia, and evidence on its use as a marker in prognosis and resuscitation. Additionally, we review the evolving role of lactate in sepsis care. We provide recommendations to aid lactate interpretation in the ED and highlight areas for future research.

Arterial vs venous lactate: Correlation and predictive value of mortality of patients with sepsis during early resuscitation phase

PURPOSE

To compare the lactate concentrations obtained from venous to those obtained from arterial blood in predicting hospital mortality of patients with sepsis and septic shock. To also assess lactate clearance as predictor for mortality.

METHODS

100 patients with septic shock were prospectively enrolled. Serum was sampled at baseline and after 6 h of resuscitation from arterial and venous lines. Demographic, severity indices, hemodynamic measures as well as lactate clearance levels were noted. Data were analyzed for bias and precision.

RESULTS

There was correlation between venous and arterial lactate concentrations at the baseline (R = 0.68) and at the 6-hour time point (R = 0.95). Venous concentrations were consistently higher than those obtained from an arterial access by 0.684 mg/dL. Further, arterial lactate level > 3.2 mmol/L and clearance of <20% were considered the cutoff for the mortality risk. While only 8% of the patients with no risk died, all 20 patients who had lactate level > 3.2 mmol/L and clearance of <20% died within the hospital.

CONCLUSION

Our data suggests a strong correlation between arterial and peripheral venous the lactate levels and in the initial phase of resuscitation in septic shock patients we can use venous lactate level as biomarker instead of arterial lactate level. The study also showed that combining lactate levels and its clearance is a reliable predictor of mortality in sepsis.

Agreement between arterial and peripheral venous lactate levels in the ED: A systematic review

BACKGROUND

In the Emergency Department, lactate measurement is a useful tool to risk-stratify critically ill patients. However, it is unclear whether arterial or peripheral venous lactate levels can be used interchangeably for this purpose. In this systematic review, we provide an overview of studies investigating the agreement between arterial and peripheral venous lactate levels in the Emergency Department.

METHODS

PubMed, Embase, the Cochrane Central Register of Controlled Trials/Wiley, Web of Science/Clarivate Analytics, and references of selected articles were assessed for all studies comparing arterial and peripheral venous lactate levels in adult patients in the emergency department. Two reviewers independently screened all potentially relevant titles and abstracts for eligibility using a standardized data-worksheet.

RESULTS

Nine studies were included. Peripheral venous lactate levels tend to be higher than arterial lactate levels with mean differences ranging from 0.18 mmol/l to 1.06 mmol/l. Importantly, poorer agreement occurs in hyperlactatemia. At a cut-of level of 1.6 mmol/l, peripheral venous lactate can rule out arterial hyperlactatemia with a sensitivity between 94% and 100%. At a cut off value of 2 mmol/l, sensitivities of 97% and 100% were found.

CONCLUSION

Agreement between arterial and peripheral venous lactate is poor in hyperlactatemia, making peripheral venous lactate an unreliable parameter to use interchangeably in the ED. In clinical practice, peripheral venous lactate can be used as a screening tool to rule out arterial hyperlactatemia at a cut-off value of 2 mmol/l. However, hyperlactatemia should be confirmed using arterial sampling in case of a peripheral venous lactate level > 2 mmol/l.

Peripheral measurements of venous oxygen saturation and lactate as a less invasive alternative for hemodynamic monitoring

Background

Peripheral measurement of venous oxygen saturation and lactate is a less invasive alternative to monitor tissue oxygenation as compared to measurements from a central venous catheter. However, there is a lack of evidence to support the use of peripheral measurements. In this study, we investigated the agreement between central and peripheral venous oxygen saturation and lactate.

Methods

We conducted a prospective observational study including 115 patients who underwent elective cardiac surgery between April and May 2015 at Rigshospitalet, Copenhagen, Denmark. Measurements were obtained simultaneously at induction of anaesthesia, upon arrival in the ICU and 3–4 h postoperatively. Bias and trending ability was identified using Bland-Altman analysis and a four-quadrant plot.

Results

Bias was 13.37% for venous oxygen saturation preoperatively (95% CI: 11.52–15.22, LoA: ±19.10, PE: 22.08%), 11.29% at arrival to the ICU (95% CI: 8.81–13.77, LoA: ±25.10, PE: 32.39%) and 16.49% at 3–4 h postoperatively (95% CI: 14.16–18.82, LoA: ±21.20, PE: 26.82%). A four-quadrant plot demonstrated an 89% concordance. Central and peripheral lactate showed a bias of 0.14 mmol/L preoperatively (95% CI: 0.11–0.17, LoA: ±0.30, PE: 32.08%), 0.16 mmol/L at arrival to ICU (95% CI: 0.09–0.23, LoA: ±0.70, PE: 38.88%) and 0.23 mmol/L at 3–4 h postoperatively (95% CI: 0.11–0.35, LoA: ±0.50, 25.18%).

Discussion

Measurements of peripheral oxygen saturation and lactate may be valuable in an emergency setting, avoiding unnecessary and time consuming application of a CVC.

Conclusion

We found a high bias but an acceptable trending ability between central and peripheral venous oxygenation. Central and peripheral lactate had excellent agreement. Further studies are necessary to validate the use of peripheral venous samples to identify patients at risk of impaired tissue oxygenation.

Close correlation between arterial and central venous lactate concentrations of children in shock: A cross-sectional study

BACKGROUND

Arterial lactate (aLact) has been widely used to guide therapeutic decisions in children with shock. We evaluated the feasibility of central venous lactate (cvLact) in assessing aLact among children with shock.

METHODS

Pairs of arterial and central venous samples for lactate concentrations were collected simultaneously during the shock and hemodynamically stable states. The results were analyzed by using a Cobas 8000 analyzer.

RESULTS

Sixty-four blood paired samples were collected from 48 patients. The overall correlation between central venous and arterial lactate concentrations was r=0.962, p<0.0001, r²=0.965. The regression equation was aLact=(0.978×cvLact)-0.137. A similar correlation was found between central venous and arterial lactate concentrations during the states of shock and stable hemodynamics (r=0.970, p<0.0001, r²=0.966 and r=0.935, p<0.0001, r²=0.962, respectively). The mean difference between central venous and arterial lactate concentrations was 0.20mmol/l (95% CI: 0.08 to 0.32) and the limits of agreement were -0.74mmol/l (95% CI: -0.94 to -0.53) and 1.13 (95% CI: 0.93 to 1.34).

CONCLUSIONS

In situations of shock where a central venous catheter is required, samples from a central vein present an acceptable and timely alternative to arterial samples for quantitating lactate concentrations.

Comparison of jugular and transverse facial venous sinus blood analytes in healthy and critically ill adult horses

OBJECTIVE

To compare blood gas, electrolyte, and metabolic analysis results between blood obtained by jugular and transverse facial venous sinus (TFVS) venipuncture in healthy adult horses and sick adult horses presented for emergency evaluation.

DESIGN

Prospective, experimental study, from June 2012 to October 2013.

SETTING

Large animal university teaching hospital.

ANIMALS

Ten healthy adult University-owned horses and 48 client-owned adult horses (≥2 years old) presenting to the large animal hospital emergency service for medical or surgical evaluation of systemic illness.

INTERVENTIONS

Venipunctures (jugular vein [JV] and TFVS) were performed using preheparinized syringes and obtained prior to institution of medical therapy. Samples were analyzed in random order within a 10-minute interval using a point-of-care blood gas analyzer (NOVA Critical Care Xpress) that also reports electrolyte and metabolite results. Comparisons between venipuncture sites were analyzed using the Student's paired t-test for normally distributed data and the Wilcoxon paired test for nonnormally distributed data. Bland-Altman analysis was used to assess agreement between venipuncture sites.

MEASUREMENTS AND MAIN RESULTS

There were no statistically significant differences found between variables for JV and TFVS in healthy horses. In sick horses, JV measurements were greater than TFVS for ionized calcium (P = 0.002) and glucose (P = 0.001), and less than TFVS for hematocrit (P = 0.015). Bland-Altman plots demonstrated small biases but overall agreement between sites.

CONCLUSIONS

The TFVS can be used interchangeably with JV for venous blood gas analysis in healthy horses. In sick horses, identified differences were small and likely not clinically important. The reliability of this point-of-care blood gas analyzer for measurement of hematocrit remains to be determined.

Correlation between Arterial Lactate and Central Venous Lactate in Children with Sepsis

Introduction. Lactate is an important indicator of tissue perfusion. The objective of this study is to evaluate if there are significant differences between the arterial and central venous measurement of lactate in pediatric patients with sepsis and/or septic shock. Methods. Longitudinal retrospective observational study. Forty-two patients were included between the age of 1 month and 17 years, with a diagnosis of sepsis and septic shock, who were admitted to the intensive care unit of a university referral hospital. The lactate value obtained from an arterial blood sample and a central venous blood sample drawn simultaneously, and within 24 hours of admission to the unit, was recorded. Results. The median age was 2.3 years (RIC 0,3-15), with a predominance of males (71.4%), having a 2.5 : 1 ratio to females. Most of the patients had septic shock (78.5%) of pulmonary origin (50.0%), followed by those of gastrointestinal origin (26.1%). Using Spearman's Rho, a 0.872 (p < 0.001) correlation was found between arterial and venous lactate, which did not vary when adjusted for age (p < 0.05) and the use of vasoactive drugs (p < 0.05). Conclusion. There is a good correlation between arterial and venous lactate in pediatric patients with sepsis and septic shock, which is not affected by demographic variables or type of vasoactive support.

Use of femoral vein catheters for the assessment of perfusion parameters

The use of central venous oxygen saturation (SvcO₂) and arterial lactate in the diagnosis of severe tissue hypoperfusion is well established, and the optimization of these parameters is currently under investigation, particularly in patients with severe sepsis/septic shock. However, the only place for deep venous puncture or the first choice for puncture is often the femoral vein. Although venous saturation obtained from blood sampling from this catheter, instead of SvcO₂, has already been used in the diagnosis of severe tissue hypoperfusion, little is known about the accuracy of the results. The venous lactate in place of arterial puncture has also been used to guide therapeutic decisions. We conducted this literature review to seek evidence on the correlation and concordance of parameters obtained by collecting femoral venous blood gases in relation to SvcO₂ and arterial lactate. Few studies in the literature have evaluated the use of femoral venous oxygen saturation (SvfO₂) or venous lactate. The results obtained thus far demonstrate no adequate agreement between SvfO₂ and SvcO₂, which limits the clinical use of SvfO₂. However, the apparent strong correlation between arterial and peripheral and central venous lactate values suggests that venous lactate obtained from the femoral vein could eventually be used instead of arterial lactate, although there is insufficient evidence on which to base this procedure at this time.

Range of blood lactate values in farm pigs prior to experimental surgery

In biomedical research the pig is widely used as an animal model for experimental surgery. Feasible monitoring tools during anaesthesia are pivotal for successful and reliable research outcome. Blood lactate values are a monitoring tool and prognostic indicator during surgery both in humans and animals. Lactate levels in pigs might be influenced by various parameters including stressful handling, breed and weight differences. To determine blood lactate levels present prior to experimental surgery, values of 124 female farm pigs were measured in venous blood samples. Pigs presented with blood lactate concentrations ranging from 0.5 to 5.5 mmol/L (median, 1.2 mmol/L; interquartile range [IQR] 1.2). Considering genetic background, Rheinhybrid/Pietrain pigs (n = 51; median, 1.4 mmol/L; IQR, 1) had significantly higher blood lactate levels compared with Landrace/Pietrain crossbred animals (n = 73; median, 1.1 mmol/L; IQR, 1; P < 0.05). Body weight had no significant effect on blood lactate levels within the evaluated range. This report can benefit research projects monitoring blood lactate values in farm pigs during experimental surgery.

Are central venous lactate and arterial lactate interchangeable? A human retrospective study

BACKGROUND

In critically ill patients, arterial blood lactate concentration (Lact(a)) and Lact(a) clearance are used for the diagnosis of shock, for prognosis assessment, and to guide therapy. In recent years, central venous oxygen saturation (ScvO(2)), a surrogate for mixed venous blood saturation, either measured by fiberoptic catheters or from central venous blood samples, was used in shock to estimate the global balance between oxygen delivery and consumption. When central venous blood is drawn for ScvO(2) measurement, it also could be used to measure central venous lactate concentration (Lact(cv)). In this study, we evaluated the utility of Lact(cv) and Lact(cv) clearance as predictors of Lact(a) and Lact(a) clearance, respectively, in critically ill patients.

METHODS

This retrospective study was performed in an intensive care unit of a regional and teaching hospital. Using the electronic registry of our blood gas analyzer from March 2007 to December 2009, we identified patients with circulatory or respiratory failure who had pairs of Lact(cv) and Lact(a) obtained within a 30-minute interval. To assess the utility of Lact(cv) as a predictor of Lact(a) above 2 and 4 mmol/L, we calculated the area under receiver operating characteristic curves (AUCs) for these thresholds. We also calculated AUC of Lact(cv) clearance to detect a Lact(a) clearance <10% or >10%.

RESULTS

Six hundred seventy-three Lact(cv)/Lact(a) pairs in 188 patients were analyzed. AUC of Lact(cv) to predict a Lact(a) above 2 and 4 mmol/L was 0.98 (95% confidence interval: 0.97-0.99) and 0.98 (95% confidence interval: 0.96-0.99), respectively. Lact(cv) with the cutoff value of 2 mmol/L can predict a Lact(a) above 2 mmol/L with sensitivity >92% and specificity >90%. AUC for Lact(cv) clearance to detect a Lact(a) clearance <10% or >10% was 0.93 or 0.94, respectively.

CONCLUSION

Lact(cv) and Lact(a) collected within a 30-minute range are interchangeable for clinical practice.