Lactate Meter Research Articles

Assessment of a portable lactate meter for field use in the white rhinoceros (Ceratotherium simum).

Blood lactate is a predictor of mortality in critically ill humans and animals. Handheld lactate meters have the potential to be used in the field to evaluate the condition of severely injured rhinoceroses but have not been compared with laboratory-based methods. Agreement between a handheld lactate meter and a laboratory method was assessed, as was the stability of rhino blood lactate in the anticoagulant sodium fluoride/potassium oxalate (fluoride/oxalate). Blood samples were obtained from 53 white rhinos that had been immobilised for management reasons. Lactate was measured by means of a handheld meter using whole blood in heparin (WBHEP), whole blood in fluoride/oxalate (WBFO) and fluoride/oxalate plasma (PFO). Results were recorded in both blood (BL) and plasma (PL) modes and compared to an established laboratory method for measuring plasma lactate. To assess the stability of lactate over time, blood lactate in fluoride/oxalate was measured on the handheld meter at intervals for up to 91 h. Agreement was best using WBFO in PL mode, with small bias (−0.16), tight 95% limits of agreement (LOA) (−1.46, 1.14) and a Pc (95% CI) of 0.97 (0.92, 0.99). The agreement was improved for all sample types when using the PL mode compared to the blood lactate (BL) mode. Blood lactate was stable in fluoride/oxalate for 91 h, with a mean change from baseline of 0.15 (−0.178, 0.478) mmol/L (mean, 95% CI). The handheld meter was found to be suitable for field use in white rhinos but provided more reliable results with the device in PL mode. Furthermore, rhino blood lactate was found to be stable in fluoride/oxalate for as long as 3 days.

Validation of a hand-held point of care device for lactate in adult and pediatric patients using traditional and locally-smoothed median and maximum absolute difference curves

BackgroundLactate is commonly used in septic patients and is a viable biomarker for trauma patients. Its pre-hospital use could assist triaging and managing patients with these conditions. MethodsWe evaluated the analytical performance of the point-of-care (POC) StatStrip Xpress Lactate Meter (Nova Biomedical) and compared it to the ABL 800 (Radiometer). We measured lactate in 250 adult and 250 pediatric whole blood samples in 2 laboratories. The performance of the POC meter was assessed by traditional linear regression and Bland-Altman plots, and locally-smoothed (LS) median absolute difference and maximum absolute difference (MAD and MaxAD) curves. ResultsThe StatStrip was linear with acceptable reproducibility at clinically relevant concentrations. Correlation with the ABL800 showed a negative bias for both populations with slope, bias ±SD (% bias) of 0.78, −0.4±0.7 (−14.5%) in children and 0.80–0.3±0.6 (−13.3%) in adults. The proportional bias appeared more significant at concentrations >4mmol/l (36.0mg/dl). The StatStrip misclassified 7.6 and 8.8% pediatric and adult samples, respectively, to lower risk categories defined using guidelines driven cut-offs. The LS MAD curves identified one breakout, concentration where the LS MAD exceeds the total allowable error limit of 0.3mmol/l (2.7mg/dl), at lactate concentrations of 3.8 and 3.2mmol/l (34.2 and 28.8mg/dl) in the pediatric and adult curves, respectively. Breakthroughs, points at which the LS MaxAD curve exceeds the 95th percentile of MaxADs, occur at concentrations above 7.5mmol/l (67.6mg/dl) for both populations where the performance of the POC meter became erratic. We concluded that if serial lactate measurements are performed, the same method should be used for baseline and follow up measurements. The LS MAD and LS MaxAD curves allowed visual and quantitative mapping of the performance of the lactate POC meter over the range of concentrations measured. ConclusionsThis approach seems useful for the identification of points at which the performance of a POC meter differs significantly from a comparison method and thresholds of poor analytical performance.

PH Response and Tooth Surface Solubility at the Tooth/Bacteria Interface

Evaluating the physiochemical processes at the tooth surface/bacteria interface is important for elucidating the etiology of dental caries. This study aimed to compare the mineral solubility and protein degradation of coronal enamel (CE) and root dentin (RD), and investigate the involvement of dissolved components in bacteria-induced pH changes using a model of tooth/bacteria interface. An experimental apparatus forming a well was made of polymethyl methacrylate, and a bovine tooth (CE or RD) specimen was fixed at the bottom of the well. A miniature pH electrode was placed on the tooth, and Streptococcus mutans NCTC 10449 cells, grown in 0.5% glucose-containing complex medium, were packed into the well. The pH at the tooth/S. mutans interface was monitored continuously for 120 min after the addition of 0.5% glucose at 37°C. S. mutans cells were recovered from the wells, and the amounts of lactate and calcium were measured using a portable lactate meter and a fluorescent dye, respectively. Proteolytic activity was also evaluated fluorometrically. The pH of the RD/S. mutans interface was significantly higher than that of the CE/S. mutans interface (30 min: 6.37 ± 0.12 vs. 6.18 ± 0.11, 60 min: 6.08 ± 0.14 vs. 5.66 ± 0.27, 90 min: 5.49 ± 0.24 vs. 5.14 ± 0.22, p < 0.05). Greater amounts of calcium were dissolved from RD (3.19 ± 0.74 µg/mL) than from CE (1.84 ± 0.68 µg/mL; p < 0.05), while similar amounts of lactate were produced. Proteolytic activity was not detected at any of the interfaces. These results indicate that RD is more soluble to bacteria-induced acidification than CE. This method can contribute to the evaluation and development of caries-preventive materials.

Effects of Systemic Metabolic Fuels on Glucose and Lactate Levels in the Brain Extracellular Compartment of the Mouse.

Classic neuroenergetic research has emphasized the role of glucose, its transport and its metabolism in sustaining normal neural function leading to the textbook statement that it is the necessary and sole metabolic fuel of the mammalian brain. New evidence, including the Astrocyte-to-Neuron Lactate Shuttle hypothesis, suggests that the brain can use other metabolic substrates. To further study that possibility, we examined the effect of intraperitoneally administered metabolic fuels (glucose, fructose, lactate, pyruvate, ß-hydroxybutyrate, and galactose), and insulin, on blood, and extracellular brain levels of glucose and lactate in the adult male CD1 mouse. Primary motor cortex extracellular levels of glucose and lactate were monitored in freely moving mice with the use of electrochemical electrodes. Blood concentration of these same metabolites were obtained by tail vein sampling and measured with glucose and lactate meters. Blood and extracellular fluctuations of glucose and lactate were monitored for a 2-h period. We found that the systemic injections of glucose, fructose, lactate, pyruvate, and ß-hydroxybutyrate increased blood lactate levels. Apart for a small transitory rise in brain extracellular lactate levels, the main effect of the systemic injection of glucose, fructose, lactate, pyruvate, and ß-hydroxybutyrate was an increase in brain extracellular glucose levels. Systemic galactose injections produced a small rise in blood glucose and lactate but almost no change in brain extracellular lactate and glucose. Systemic insulin injections led to a decrease in blood glucose and a small rise in blood lactate; however brain extracellular glucose and lactate monotonically decreased at the same rate. Our results support the concept that the brain is able to use alternative fuels and the current experiments suggest some of the mechanisms involved.

Validating a point of care lactate meter in adult patients with sepsis presenting to the emergency department of a tertiary care hospital of a low- to middle-income country

Timely identification of high blood lactate levels in septic patients may allow faster detection of those patients requiring immediate resuscitation. Point-of-care (POC) testing is being increasingly utilized in the emergency department (ED). We examined the accuracy and time-saving effect of a handheld POC lactate device for the measurement of fingertip and whole blood lactate as compared with reference laboratory blood testing in septic ED patients. A convenience sample of adult ED patients receiving serum lactate testing were enrolled prospectively in the ED of a multidisciplinary tertiary care hospital serving the population of one of the major cities of Pakistan. Participants underwent fingertip POC lactate measurement with a portable device simultaneous whole blood sampling for analysis by both the POC lactate device and standard laboratory method. Lactate measurements were compared by intraclass correlation (ICC) and Bland and Altman plots. Forty-three septic patients were included in the study. The fingertip POC & whole blood POC lactate measurements each correlated tightly with the reference method (ICC=0.93 & ICC=0.92, respectively). Similarly at 6 hours, the fingertip POC & whole blood POC lactate measurements demonstrated satisfactory correlation with the reference method (ICC=0.95 & ICC=0.97, respectively). Fingertip POC lactate measurement is an accurate method to determine lactate levels in septic ED patients.

Prehospital Lactate Measurement by Emergency Medical Services in Patients Meeting Sepsis Criteria.

IntroductionWe aimed to pilot test the delivery of sepsis education to emergency medical services (EMS) providers and the feasibility of equipping them with temporal artery thermometers (TATs) and handheld lactate meters to aid in the prehospital recognition of sepsis.MethodsThis study used a convenience sample of prehospital patients meeting established criteria for sepsis. Paramedics received education on systemic inflammatory response syndrome (SIRS) criteria, were trained in the use of TATs and hand-held lactate meters, and enrolled patients who had a recent history of infection, met ≥ 2 SIRS criteria, and were being transported to a participating hospital. Blood lactate was measured by paramedics in the prehospital setting and again in the emergency department (ED) via usual care. Paramedics entered data using an online database accessible at the point of care.ResultsPrehospital lactate values obtained by paramedics ranged from 0.8 to 9.8 mmol/L, and an elevated lactate (i.e. ≥ 4.0) was documented in 13 of 112 enrolled patients (12%). The unadjusted correlation of prehospital and ED lactate values was 0.57 (p< 0.001). The median interval between paramedic assessment of blood lactate and the electronic posting of the ED-measured lactate value in the hospital record was 111 minutes. Overall, 91 patients (81%) were hospitalized after ED evaluation, 27 (24%) were ultimately diagnosed with sepsis, and 3 (3%) died during hospitalization. Subjects with elevated prehospital lactate were somewhat more likely to have been admitted to the intensive care unit (23% vs 15%) and to have been diagnosed with sepsis (38% vs 22%) than those with normal lactate levels, but these differences were not statistically significant.ConclusionIn this pilot, EMS use of a combination of objective SIRS criteria, subjective assessment of infection, and blood lactate measurements did not achieve a level of diagnostic accuracy for sepsis that would warrant hospital prenotification and committed resources at a receiving hospital based on EMS assessment alone. Nevertheless, this work provides an early model for increasing EMS awareness and the implementation of novel devices that may enhance the prehospital assessment for sepsis. Additional translational research studies with larger numbers of patients and more robust methods are needed.

The handheld blood lactate analyser versus the blood gas based analyser for measurement of serum lactate and its prognostic significance in severe sepsis

BackgroundThis study was done to compare the accuracy of the Lactate Pro LT 1710 (Arkray Inc., Kyoto, Japan) with the Combiline Plus (Eschweiler GmbH & Co. KG Holzkoppelweg, Kiel, Germany), and also, to analyze the prognostic significance of serum lactates and Simplified Acute Physiology Score 3 (SAPS 3) in patients of severe sepsis. Methods106 patients of severe sepsis admitted to the ICU were screened. The serum lactate from an arterial sample analyzed in both the machines was recorded at admission and at 48h. These patients were then followed up to the 28th day for mortality. ResultsThe Lactate Pro LT 1710 handheld point of care lactate meter provides consistent results comparable to the Eschweiler Combiline blood gas analyser. Serum lactate concentration was significantly higher in nonsurvivors at the time of admission (3.30±1.26) and at 48h (4.34±1.73). Lactate clearance at 48h appears to be a better predictor of mortality than the lactate levels at 0h and 48h. The mean SAPS 3 at admission amongst survivors was significantly less as compared to nonsurvivors. The SAPS 3 had improved to 47.44 (±11.79) in survivors at 48h, while in nonsurvivors it had worsened to 81.98 (±12.32) (p=0.00); thus, a worsening SAPS 3 at 48h had a poorer prognosis. ConclusionsThe Lactate Pro LT 1710 provides similar results to the Combiline Eschweiler blood gas analyser and is a cheaper alternative. It would prove to be a boon in peripheral hospitals in the aggressive management of critically ill patients.

Effects Of Attention-Deficit/Hyperactivity Disorder Medications On Resistance-Exercise-Induced Hypoalgesia, Perceived Exertion, Heart Rate, And Blood Lactate

PURPOSE:An increase in prescribed stimulant medication for the treatment of Attention-Deficit/Hyperactivity Disorder (ADHD) has led to treatment misuse as a result of the ability of these medications to improve concentration and decrease fatigue. Although they provide cognitive benefits, the effects of stimulant treatment for ADHD during physical activity are fairly unknown. The primary goal of this study was to investigate the effects of ADHD medications on resistance exercise-induced pain perception, perceived exertion, heart rate, and blood lactate concentrations. METHODS:Thirty college-age students (10 no ADHD diagnosis, 10 ADHD diagnosis, and 10 ADHD diagnosis with medications) completed 2 sessions: 1) a maximal testing session and 2) an experimental session consisting of 3 consecutive dynamic resistance exercise circuits. Each circuit was comprised of 12 repetitions of 9 resistance exercises at 60% of 1-repetition maximum using a 1:1 work to rest ratio. Pain and blood lactate concentrations were measured pre- and post-exercise using a pressure algometer and lactate meter, respectively. Heart rate and perceived exertion were measured during the exercise bout. RESULTS:Participants displayed exercise-induced hypoalgesia ([INCREMENT]17.8% ± 5.2, p = 0.002) 1-min post-exercise, accompanied by an increase in blood lactate (12.47 ± 0.66mM, p = 0.000). Moreover, participants displayed significant elevations in heart rate (p = 0.000) and perceived exertion (p = 0.000) for the duration of the exercise bout. These findings for pain tolerance, lactate, heart rate, and perceived exertion were similar regardless of condition (no ADHD diagnosis vs. ADHD without medications vs. ADHD with medications). CONCLUSIONS:Dynamic resistance exercise produces increases in pain tolerance, perceived exertion, heart rate, and blood lactate. The effects of resistance exercise are not altered by ADHD diagnosis or psychostimulant medication use for ADHD. These findings are intriguing given the known ergogenic and analgesic effects of caffeine, a less potent stimulant.

Blood Lactate Levels Measured Using Finger Prick vs. Venous Blood Draw Methods

Audriana Mooth, Paul Hafen, Andy Larsen, Kurtis Rosengreene, Gregory Savio, Sean Catlett, Parker Wood, Mark McKay, Pat Vehrs, FACSM. Brigham Young University, Provo, UT. (Sponsor: Pat Vehrs, FACSM) (No relationships reported) Blood lactate measurements can be a useful tool in developing endurance training programs, and is used in different settings by athletes hoping to improve their performance. In most cases, handheld blood lactate meters are the most practical way to measure blood lactate, and can take measurements from a finger prick or sample of blood drawn intravenously. PURPOSE: The purpose of this study was to compare the blood lactate measurements taken from a finger prick versus an intravenous blood draw during steady-state aerobic exercise using the NOVA Lactate Plus handheld meter. METHODS: Seven male runners, ages 18-39, with a weekly training mileage of 25-60 miles and 5K run times of less than 18:25 participated in this study. Exercise testing determined lactate threshold and VO2max for all six volunteers, and maximal lactate steady-state (MLSS) was found for each participant as they completed multiple submaximal steady-state runs. An intravenous catheter positioned in the antecubital vein was used to obtain blood samples during the submaximal steady-state runs. Finger prick samples were taken simultaneously. The NOVA Lactate Plus was used to determine blood lactate levels using the intravenously drawn blood and finger prick samples. Lactate was measured twice from the intravenously drawn blood and once from the finger prick. RESULTS: The lactate values from the two samples of intravenously drawn blood were not significantly different (0.009 mmol/L; p=0.790) and were highly correlated (R=0.995). The lactate values from the finger prick blood samples were significantly different (p=0.0001) than the intravenous blood samples. On average, the lactate values measured from the finger prick samples were 1.41 mmol/L greater than the lactate values measured from the intravenous blood samples. CONCLUSIONS: Compared to intravenous blood samples, finger prick samples tend to overestimate blood lactate levels. Use caution when using lactate measurements from finger prick blood samples to develop endurance.

Comparison of Physiological Responses following Blood Flow Restriction between Low-Intensity Resistance Exercise and Running Exercise

It is well known that low-intensity resistance exercise combined with blood flow restriction (LIRE + BFR) can lead to increase in the metabolic stress and motor unit recruitment, which may contribute to greater gains in muscle hypertrophy, strength and endurance after a period of training. However, the effect of running exercise combined with blood flow restriction (RE + BFR) on acute physiological responses is still unknown. PURPOSE: This study aimed to investigate the physiological responses following LIRE +BFR or RE + BFR. METHODS: Twelve male track and field athletes were recruited to participate in this study. All participants underwent two conditions: (1) LIRE (41.3 ± 6.1 kg, 30 rep x 5 sets, 1min rest interval) + BFR (149.7 ± 4.9 mmHg). (2) RE (8.4 ± 1.7 km/hr, 2 min x 5 sets, 1min rest interval) + BFR. Heart rate (HR) and Ratings of perceived exertion (RPE) were obtained (pre-ex, post-ex and 5 min post-ex) using the Heart Rate Monitor (Polar RS800CX, Polar Electro Oy, Finland) and Borg RPE Scale (6-20 point scale). Blood lactate (pre-ex and 3 min post-ex), muscle tissue oxygen saturation (from 5 min pre-ex to 5 min post-ex) and muscle activation (during-ex) were also determined using lactate meter (Lactate Pro™, KDK Corporation, Japan), near-infrared spectroscopy (Portamon™, AS Zetten, Netherlands) and electromyography machine (TeleMyo DTS®, Noraxon, USA). One-way ANOVA with repeated measures was performed to examine the differences of muscle activation between the treatments. Two-way ANOVA (treatment x time) with repeated measures was used to evaluate the treatment effects on other measured variables. RESULTS: Both LIRE +BFR and RE + BFR elicited higher HR (post-ex, 162.7 ± 4.9 vs. 163.5 ± 9.2 bpm), RPE (post-ex, 16.1 ± 0.7 vs. 15.9 ± 0.8), blood lactate (3 min post-ex, 5.6 ± 1.8 vs. 5.7 ± 2.2 mmol/L) response and lower muscle tissue oxygen saturation (during-ex, 47.5 ± 6.7 vs. 46.7 ± 4.6 %). However, no significant differences were observed between the treatments. Furthermore, RE + BFR resulted in greater muscle activation of the tibialis anterior (+18.7%), biceps femoris (+23.1%) and gastrocnemius (+17.7%) muscles when compared with LIER + BFR. CONCLUSION: RE + BFR may be a practical training strategy for promoting muscular fitness on track and field athletes.

Preliminary investigation of the area under the L-lactate concentration-time curve (LACArea) in critically ill equine neonates.

BackgroundA variety of measures of l‐lactate concentration ([LAC]) in the blood of critically ill neonatal foals have shown utility as prognostic indicators. These measures, evaluating either the severity of hyperlactatemia or the duration of exposure to hyperlactatemia, perform fairly well and have correctly classified 75–80% of foals examined in several studies. The area under the l‐lactate concentration versus time curve (LAC Area) encompasses both severity and duration of hyperlactatemia and should improve correct classification of patient survival.Hypothesis/Objectives LAC Area is larger in nonsurviving critically ill neonatal foals.AnimalsForty‐nine foals admitted for critical illness to 1 of 4 referral hospitals.MethodsWhole blood was obtained at admission and 6, 12, 18, and 24 hours after admission for measurement of l‐lactate using a handheld lactate meter. LAC Area was calculated for: admission–6, 6–12, 12–18, 18–24 hours, and admission–24 hours using the trapezoidal method and summing the 6‐hours interval areas to determine total 24 hours area. Differences between survivors and nonsurvivors were determined using robust regression and Kruskal–Wallis testing, P < .05.Results LAC Area was significantly larger in nonsurviving foals (n = 9) than in surviving foals (n = 40) at all time periods examined.Conclusions and Clinical ImportanceDifferences in LAC Area between surviving and nonsurviving critically ill neonatal foals are large and support further investigation of this method as an improved biomarker for survival in critically ill neonatal foals is indicated.

Evaluation of pre-hospital point-of-care testing for lactate in sepsis and trauma patients

Objective: Lactate is a significant marker of critical illness and mortality in sepsis and trauma patients. The purpose of this study is to evaluate point-of-care lactate testing by paramedics in a UK ambulance service. Methods: Selected enhanced care paramedics were trained to use the lactate meter in patients with suspected sepsis and patients who trigger the major trauma bypass protocol. Feedback was collected on the practicalities of using the meter and the potential impact on the diagnosis of sepsis. Results: Data were collected on 114 patients, 96% had suspected sepsis (n=109) and 4% (n=5) were patients who had sustained trauma. The participants found that the ability to take lactate readings was useful and increased their confidence in their clinical decision making. Conclusions: Point-of-care lactate measurement is feasible in pre-hospital care and appears to support paramedics in their decision making.

Validation of the handheld Lactate-Pro analyzer for measurement of blood L-lactate concentration in cattle.

Blood L-lactate concentration (LAC) can be used for various diagnostic purposes in cattle. As multiple handheld analyzers for LAC exist, it is important to validate their use in cattle in comparison with reference laboratory blood analyzers. The objectives of this study were to validate the handheld Lactate Pro meter (LacP) including reproducibility, and compare the measurements with the StatProfile (StatP) as a gold standard. In addition, diagnostic sensitivity and specificity, and the impact of HCT on LAC measured by both analyzers were assessed. A cohort of 64 cattle with acute medical and surgical conditions was studied. Whole blood samples in heparin lithium tubes were analyzed upon arrival with both StatP and LacP. Twenty-three samples were immediately retested to assess intra-assay coefficient of variation (CV). The HCT values were also recorded. The LAC using LacP was highly correlated with the StatP (r=0.9736 [95% confidence interval [CI]: 0.9562-0.9841]). The LacP underestimated LAC (mean difference:-0.9mmol/L, 95% CI:-3.1mmol/L to 1.3mmol/L). The intra-assay CV was excellent (4.77%). No significant correlation was observed between LacP or StatP and HCT (P=.39 and .09, respectively). Sensitivity and specificity for LacP were 91.7% (95% CI: 76.4-97.8%) and 100% (83.4-100%, cutoff of 4mmol/L), and 78.6% (58.5-90.9%) and 100% (87.0-100%, cutoff of 6mmol/L). The LacP handheld lactate meter can be used safely and reliably cow-side, although it underestimates LAC value when compared with a standard laboratory analyzer especially for LAC≥10.0mmol/L. The LAC value was not influenced by HCT in this study.

Validation of the Lactate Plus Lactate Meter in the Horse and Its Use in a Conditioning Program

The equine industry has a need for a convenient, rapid, and reliable method of measuring blood lactate concentrations ([LA]). We hypothesized that the handheld Lactate Plus lactate meter (LPlus), developed and tested for use in humans, would provide dependable results when used in horses undergoing an exercise conditioning program and that horse's fitness would improve following individualized conditioning based on each horse's velocity at which [LA] = 4 mmol/L (VLA4) was reached. Five adult horses underwent a 4-week training program that consisted of 3 exercise bouts/wk. Horses were subjected to an incremental step standardized exercise test (SET) before starting (SET-1) and after the completion of the program (SET-2). Blood samples were collected before each increase in speed until [LA] reached ≥4 mmol/L, and then the SET was terminated. The [LA] sample range in our study was 0–8 mmol/L. Blood was analyzed at the time of collection using a calibrated LPlus, and plasma was collected for [LA] determination using the lactate dehydrogenase–based enzymatic colorimetric method. Although the LPlus tended to significantly underestimate [LA] by 0.39 mmol/L (P < .001), the LPlus proved to be a dependable device for use in horses based on good correlation with the biochemical analysis (r = 0.978) and Bland–Altman limits of agreement and 95% confidence intervals. All horses showed an increase in VLA4 from SET-1 to SET-2, consistent with improved fitness following our 3 exercise bout/wk training protocol. The LPlus can reliably be used in horses to determine [LA] ranging from 0–8 mmol/L. When determining serial [LA], analytical techniques should not be used interchangeably.

Evaluation of Three Handheld Lactate Meters for Measuring Hemolymph L-Lactate in Decapod Crustaceans

The aim of this study was to determine the reliability and accuracy of 3 commercially available handheld lactate meters when measuring hemolymph L-lactate in decapod crustaceans. The instruments tested were Accutrend Plus (AP), Lactate Scout (LS), and Lactate Plus (LP), and all models were tested in triplicate and compared with a commonly used enzymatic kit for L-lactate quantification (TB-kit). The Norway lobster Nephrops norwegicus and the European lobster Hommarus gammarus were used as model organisms, with emersion as an invoker of hemolymph L-lactate. Between-method comparisons were investigated by determining correlations (Pearson's r) and concordance (concordance correlation coefficient (CCC) and Bland-Altmand's 95% limit of agreement (95% LOA)) between handheld instruments and TB-kit. Within-instrument variation was tested by calculating the coefficient of variation (CV), and the average absolute deviation from the mean (AD). The within-instrument variation was low for all models (CV, 3.8–6.1%; AD, <0.3 mM), showing high reproducibility of technical replicates. A significant correlation with TB-kit was found for all handheld instruments (AP, r = 0.970; LS, r =; 0.956; LP, r = 0.950). For both AP and LS, there was a moderate and significant concordance with TB-kit (AP, CCC = 0.945; LS, CCC = 0.940). The mean difference from TB-kit was -1.42 mM (95% LOA,-4.50–1.66 mM) for AP and 1.19 mM (95% LOA,-3.13–5.51 mM) for LP. Emersion experiments with the European lobster showed that AP and LS were in line with TB-kit in terms of detecting differences in L-lactate levels between groups of animals. As a result of the high frequency of error readings from LP, this instrument was not considered reliable when measuring L-lactate in decapod crustaceans. In conclusion the handheld instruments AP and LS are found to be reliable instruments when measuring hemolymph L-lactate in decapod crustaceans. Comparison of results from different methods should be avoided, and in cases when accurate absolute measurement of L-lactate is needed, methods allowing for greater accuracy and resolution should be used.

A validation study: assessing the reliability of the hand held StatStripXPress lactate meter to test lactate in amniotic fluid.

BackgroundThe level of lactate in amniotic fluid may provide useful clinical information when assessing whether a woman in labour is experiencing labour dystocia. If so, a rapid, reliable method to assess the concentration of amniotic fluid lactate at the bedside will be required in order to be clinically relevant. To assess efficacy, we compared the hand held StatStripXPreass lactate meter (Nova Biomedical) to the reference laboratory analyser ABX Pentra 400 (Horiba) in a controlled environment. Baseline biological lactate concentration was measured in triplicate and samples of a known quantity of thawed amniotic fluid spiked with lactate substrate (62 mmol/L) from the LDH12 kit (Roche, SUI) to yield a predetermined lactate concentration above baseline then measured in triplicate. Deming Regression was used to determine the linear agreement and a Bland Altman plot used to determine the paired agreement across the range of values.FindingsThe mean difference with Bland-Altman plot between hand held meter and lab instrument was -1.0 mmol/L (SD 3.0 mmol/L) with 95% CI limits of agreement between -6.9 mmol/L to 4.9 mmol/L. The Deming regression co-efficient or slope of agreement was 0.91 (SD of 0.21).ConclusionThe measurement of amniotic fluid lactate using the StatStripXPress hand held meter was reliable compared to reference laboratory methods for measuring lactate levels in amniotic fluid.

Accuracy of a hand-held lactate meter in measuring umbilical cord blood lactate at all lactate levels

Objective: Fetal scalp lactate has largely replaced pH analysis to assess intrapartum hypoxia. Many obstetrics units use hand-held lactate meters to measure umbilical blood because of its affordability and ease of use. We sought to investigate the agreement of Lactate ProTM with a reference method blood gas analyser and to determine its usefulness with a recommended cutoff value of 4.8 mmol/L. Methods: Prospective study carried out at a tertiary institution where 237 arterial and 233 venous samples from umbilical cords of 16 elective caesarean and 285 emergency deliveries were measured using Lactate ProTM and ABL735 Sesries Acid-Base analyser. Limits of agreement were analysed using Bland-Altman plots. Results: Lactate ProTM differentiated fewer deliveries as “high risk” (≥4.8 mmol/L) and more as “low risk” (TM) were –1.46 - 0.97 mmol/L for arterial lactate levels arterial lactate levels ≥ 4.8 mmol/L. Conclusion: There was a poorer agreement between the two devices at higher lactate values. Lactate ProTM underestimates by up to 3.2 mmol/L; a 4.8 mmol/L reading may actually signify a lactate level of 8.0 mmol/L, indicating severe metabolic acidosis. We caution the use of this device in assessing fetal lactate levels.

Evaluation of 4 Point‐of‐Care Units for the Determination of Blood l‐Lactate Concentration in Cattle

Despite being used commonly in bovine medicine, information on reliability of point-of-care (POC) lactate meters is limited. To determine the validity of 4 commercially available POC lactate meters in cattle. Cattle with various diseases (n = 120). Blood samples collected from the jugular vein were processed immediately on POC lactate meters. Plasma l-lactate concentration was measured by the enzymatic-colorimetric method (ELISA). Data were subjected to Friedman's test for comparison, Passing-Bablok regression and Bland-Altman plot analyses for reliability, and receiver operating characteristics analysis for sensitivity (Se) and specificity (Sp). The POC lactate meters were highly correlated with ELISA (r = 0.98-0.99) despite disagreements among units. When regressed on ELISA, blood l-lactate concentrations generated from Accutrend Plus and Lactate Pro were linear up to 16.6 and 15.7 mmol/L, respectively, whereas those generated from i-STAT and Lactate Scout were linear up to 19.5 and 19.7 mmol/L, respectively. All POC lactate meters had a Se of 100% with Sp of 95.7-98.6% at a plasma l-lactate cut-off concentration of 4 mmol/L. i-STAT had the best accuracy (99.0%) and precision (99.8%), the best linear fit (y = -0.13 + 1.04X) yielding the lowest bias (-6.6%) as well as the highest Se (100%) and Sp (98.6%). Despite high correlation with the reference method, dilution is needed for Accutrend Plus/Lactate Pro and i-STAT/Lactate Scout if concentrations >15 and 20 mmol/L, respectively. i-STAT provided the most accurate and precise results.

A pilot study to determine the feasibility of collecting amniotic fluid samples from women during labour and measuring amniotic fluid lactate at point of care

BackgroundThe level of lactate in amniotic fluid may provide useful clinical information when assessing progress of a woman’s labour and if so, a rapid, reliable method to assess amniotic fluid lactate is required in order to be clinically relevant. However, measuring lactate levels in amniotic fluid, using portable, handheld lactate meters may be less accurate than reference laboratory instruments designed to measure lactate levels in aqueous solutions. Prior to conducting a large study, we assessed recruitment, consent and sampling procedures, and the accuracy of a handheld lactate meter to measure lactate in amniotic fluid. We compared amniotic fluid lactate results obtained using the hand held Lactate Pro (Arkray) to results obtained using reference laboratory methods ABX Pentra 400 (Horiba).ResultsWe recruited 35 nulliparous women during their antenatal hospital visits and tested amniotic fluid samples collected from 20 labouring women. The handheld Lactate Pro meter was found accurate from 9–20 mmol/L with a Passing & Bablok regression of y = 0.18 + 0.97x (95% CI 0.76–1.45). Amniotic fluid lactate results remained reliable in the presence of potential contaminants commonly encountered during labour; obstetric lubricant, blood and meconium.ConclusionThe measurement of amniotic fluid lactate using the Lactate Pro meter was reliable compared to reference laboratory methods for measuring lactate levels in amniotic fluid. The pilot study enabled the refinement of information, recruitment, consenting and sampling procedures prior to commencing a large cohort study.

Early Detection and Treatment of Patients with Severe Sepsis by Prehospital Personnel

BackgroundSevere sepsis is a condition with a high mortality rate, and the majority of patients are first seen by Emergency Medical Services (EMS) personnel. ObjectiveThis research sought to determine the feasibility of EMS providers recognizing a severe sepsis patient, thereby resulting in better patient outcomes if standard EMS treatments for medical shock were initiated. MethodsWe developed the Sepsis Alert Protocol that incorporates a screening tool using point-of-care venous lactate meters. If severe sepsis was identified by EMS personnel, standard medical shock therapy was initiated. A prospective cohort study was conducted for 1 year to determine if those trained EMS providers were able to identify 112 severe sepsis patients before arrival at the Emergency Department. Outcomes of the sample of severe sepsis patients were examined with a retrospective case control study. ResultsTrained EMS providers transported 67 severe sepsis patients. They identified 32 of the 67 severe sepsis patients correctly (47.8%). Overall mortality for the sample of 112 severe sepsis patients transported by EMS was 26.7%. Mortality for the sample of severe sepsis patients for whom the Sepsis Alert Protocol was initiated was 13.6% (5 of 37), crude odds ratio for survival until discharge was 3.19 (95% CI 1.14–8.88; p = 0.040). ConclusionsThis pilot study is the first to utilize EMS providers and venous lactate meters to identify patients in severe sepsis. Further research is needed to validate the Sepsis Alert Protocol and the potential associated decrease in mortality.