Blood Lactate Measurements Research Articles

Agreement Between Heart Rate Variability - Derived vs. Ventilatory and Lactate Thresholds: A Systematic Review with Meta-Analyses.

Determining thresholds by measuring blood lactate levels (lactate thresholds) or gas exchange (ventilatory thresholds) that delineate the different exercise intensity domains is crucial for training prescription. This systematic review with meta-analyses aims to assess the overall validity of the first and second heart rate variability - derived threshold (HRVT1 and HRVT2, respectively) by computing global effect sizes for agreement and correlation between HRVTs and reference - lactate and ventilatory (LT-VTs) - thresholds. Furthermore, this review aims to assess the impact of subjects' characteristics, HRV methods, and study protocols on the agreement and correlation between LT-VTs and HRVTs. Systematic computerised searches for studies determining HRVTs during incremental exercise in humans were conducted. The agreements and correlations meta-analyses were conducted using a random-effect model. Causes of heterogeneity were explored by subgroup analysis and meta-regression with subjects' characteristics, incremental exercise protocols, and HRV methods variables. The methodological quality was assessed using QUADAS-2 and STARDHRV tools. The risk of bias was assessed by funnel plots, fail-safe N test, Egger's test of the intercept, and the Begg and Mazumdar rank correlation test. Fifty included studies (1160 subjects) assessed 314 agreements (95 for HRVT1, 219 for HRVT2) and 246 correlations (82 for HRVT1, 164 for HRVT2) between LT-VTs and HRVTs. The standardized mean differences were trivial between HRVT1 and LT1-VT1 (SMD = 0.08, 95% CI -0.04-0.19, n = 22) and between HRVT2 and LT2-VT2 (SMD = -0.06, 95% CI -0.15-0.03, n = 42). The correlations were very strong between HRVT1 and LT1-VT1 (r = 0.85, 95% CI 0.75-0.91, n = 22), and between HRVT2 and LT2-VT2 (r = 0.85, 95% CI 0.80-0.89, n = 41). Moreover, subjects' characteristics, type of ergometer, or initial and incremental workload had no impact on HRVTs determination. HRVTs showed trivial differences and very strong correlations with LT-VTs and might thus serve as surrogates. These results emphasize the usefulness of HRVTs as promising, accessible, and cost-effective means for exercise and clinical prescription purposes.

Precision and accuracy of four handheld blood lactate analyzers across low to high exercise intensities.

To evaluate the precision and accuracy in measured blood lactate concentrations among four commonly used handheld lactate analyzers compared to two stationary analyzers. Venous blood samples were taken at exercise intensities ranging from low to high. The blood lactate concentration was measured simultaneously with four pairs of handheld lactate analyzers (two new units of each brand: Lactate Plus, Lactate Pro2, Lactate Scout 4, and TaiDoc TD-4289), and compared with two stationary analyzers (Biosen C-Line and YSI Sport 1500). Measurements were repeated for a range of blood lactate concentrations (measured with Biosen) from 0.88 to 4.89mM with a median difference between measurements of 0.10 mM. The mean relative differences to the Biosen analyzer were 7% (Plus), 7% (Pro), 10% (Scout), 42% (Tai), and 32% (Ysi). The residual standard errors after linear regression against Biosen were 0.18 mM (Plus), 0.20 mM (Pro), 0.22 mM (Scout), 0.15 mM (Tai), and 0.06 mM (Ysi). Accordingly, a blood lactate concentration of 3mM measured with Biosen yielded 95% prediction intervals that were 0.72 mM (Plus), 0.80 mM (Pro), 0.87 mM (Scout), 0.60 mM (Tai), and 0.23 mM (Ysi) wide. Compared to our two stationary analyzers, the precision of the four handheld lactate analyzers evaluated in this study was poor. Among the four, Tai was the most precise; however, this analyzer had low accuracy with a substantial mean difference to the reference analyzer.

The absolute lactate levels versus clearance for prognostication of post-cardiotomy patients on veno-arterial ECMO.

Veno-arterial extracorporeal membrane oxygenation (VA-ECMO) is a life-saving procedure for supporting patients with cardiogenic shock after cardiac surgery. This work aimed to analyse the impact of changes in blood lactate levels on the survival of patients on post-cardiotomy ECMO (PC-ECMO) and whether lactate clearance (LC) performs better than absolute lactate levels. We retrospectively analysed the data of adult patients who received PC-ECMO at our centre between 2016 and 2022. The primary outcome was the in-hospital mortality rate. Arterial lactate levels were measured at ECMO initiation, peak and 12 and 24h after VA-ECMO support. LC was calculated at 12 and 24h. Out of 2368 patients who received cardiac surgeries, 152 (median age, 48years; 57.9% of them were men) received PC-ECMO. Of them, 48 (31.6%) survived and were discharged, while 104 (68.4%) died during the index hospitalization. Non-survivors had higher frequencies of atrial fibrillation (41.35% vs. 12.5%, P<0.001), chronic kidney disease (26.9% vs. 6.3%, P=0.004), prolonged cardiopulmonary bypass (237 vs. 192min, P=0.016) and aortic cross-clamping times (160 vs. 124min, P=0.04) than survivors. Non-survivors had a significantly higher median Sequential Organ Failure Assessment (SOFA) score at ECMO initiation (13.5 vs. 9, P<0.001) and a lower median Survival After Veno-arterial ECMO (SAVE) score (-3 vs. 3, P<0.001) with higher SAVE classes (P<0.001) than survivors. After 12h of VA-ECMO support, the blood lactate level was negatively correlated with LC in survivors (r=-0.755, P<0.001) and non-survivors (r=-0.601, P<0.001). After 24h, the same negative correlation was identified between survivors (r=-0.764, P<0.001) and non-survivors (r=-0.847, P<0.001). Blood lactate levels measured at 12h to determine hospital mortality [>8.2mmol/L, area under the receiver operating characteristic curve (AUROC): 0.868] and 24h (>2.6mmol/L, AUROC: 0.896) had the best performance, followed by LC-T12 (<21.94%, AUROC: 0.807), LC-T24 (<40.3%, AUROC: 0.839) and peak blood lactate (>14.35mmol/L, AUROC: 0.828). The initial pre-ECMO blood lactate (>6.25mmol/L, AUROC: 0.731) had an acceptable ability to discriminate mortality but was less than the following measurements and clearance. Kaplan-Meier curves demonstrated that LC of <21.94% at T12h and <40.3% at T24h was associated with decreased survival (log-rank P<0.001). Cox proportional hazards regression analysis for mortality revealed that LC of <21.94% at T12h had an adjusted hazard ratio (HR) of 2.73 [95% confidence interval (CI): 1.64-5.762, P<0.001] and LC of <40.3% at T24h had an adjusted HR of 1.98 (95% CI: 1.46-4.173, P<0.001). The predictors of hospital mortality after PC-ECMO were the lactate level at 12h [odds ratio (OR): 1.67, 95% CI: 1.121-2.181, P=0.001], initial SOFA score (OR: 1.593, 95% CI: 1.15-2.73, P<0.001), initial blood lactate (OR: 1.21, 95% CI: 1.016-1.721, P=0.032) and atrial fibrillation (OR: 6.17, 95% CI: 2.37-57.214, P=0.003). Bivariate models using lactate levels and clearance at the same points revealed that blood lactate levels performed better than the clearance percentage. Serial measurements of arterial blood lactate and LC help in obtaining early prognostic guidance in adult patients supported by VA-ECMO after cardiac surgery. Absolute lactate levels, compared with LC at the same time points, demonstrated better performance in differentiating mortality.

Effects of acute beetroot juice intake on performance, maximal oxygen uptake, and ventilatory efficiency in well-trained master rowers: a randomized, double-blinded crossover study.

Beetroot juice (BRJ) intake has been considered a practical nutritional strategy among well-trained athletes. This study aimed to assess the effects of BRJ intake on performance, cardiorespiratory and metabolic variables during a simulated 2000-meter rowing ergometer test in well-trained master rowers. Ten well-trained male master rowers (30-48 years) participated in a randomized, double-blind, crossover design for 3 weeks. In the first week, a researcher explained all the experimental procedures to the participants. In the next two weeks, the participants were tested in 2 rowing ergometer sessions, separated from each other by a 7-day washout period. In both strictly identical sessions, the participants randomly drank BRJ or placebo (PL) 3 hours before the start of the tests. Subsequently, the participants carried out the 2000-meter rowing ergometer tests. Oxygen saturation and blood lactate measurements were performed before starting (pretest) and at the end of the test (posttest). Performance parameters and cardiorespiratory variables were recorded during the rowing ergometer test. An improvement in time trial performance was observed, with a mean difference of 4 seconds (90% confidence limits ± 3.10; p ≤ 0.05) compared to PL. Relative and absolute increased (mean difference of 2.10 mL·kg-1·min-1, 90% confidence limits ± 1.80; mean difference of 0.16 L·min-1 90% confidence limits ± 0.11, respectively; p ≤ 0.05) compared to PL. No ergogenic effect was observed on ventilatory efficiency and blood lactate concentrations after BRJ intake. Acute BRJ intake may improve time trial performance as well as in well-trained master rowers. However, BRJ does not appear to improve ventilatory efficiency.

Trends in Empiric Broad-Spectrum Antibiotic Use for Suspected Community-Onset Sepsis in US Hospitals

Little is known about the degree to which suspected sepsis drives broad-spectrum antibiotic use in hospitals, what proportion of antibiotic courses are unnecessarily broad in retrospect, and whether these patterns are changing over time. To describe trends in empiric broad-spectrum antibiotic use for suspected community-onset sepsis. This cross-sectional study used clinical data from adults admitted to 241 US hospitals in the PINC AI Healthcare Database. Eligible participants were aged 18 years or more and were admitted between 2017 and 2021 with suspected community-onset sepsis, defined by a blood culture draw, lactate measurement, and intravenous antibiotic administration on admission. Empiric anti-methicillin-resistant Staphylococcus aureus (MRSA) and/or antipseudomonal β-lactam agent use. Annual rates of empiric anti-MRSA and/or antipseudomonal β-lactam agent use and the proportion that were likely unnecessary in retrospect based on the absence of β-lactam resistant gram-positive or ceftriaxone-resistant gram-negative pathogens from clinical cultures obtained through hospital day 4. Annual trends were calculated using mixed-effects logistic regression models, adjusting for patient and hospital characteristics. Among 6 272 538 hospitalizations (median [IQR] age, 66 [53-78] years; 443 465 male [49.6%]; 106 095 Black [11.9%], 65 763 Hispanic [7.4%], 653 907 White [73.1%]), 894 724 (14.3%) had suspected community-onset sepsis, of whom 582 585 (65.1%) received either empiric anti-MRSA (379 987 [42.5%]) or antipseudomonal β-lactam therapy (513 811 [57.4%]); 311 213 (34.8%) received both. Patients with suspected community-onset sepsis accounted for 1 573 673 of 3 141 300 (50.1%) of total inpatient anti-MRSA antibiotic days and 2 569 518 of 5 211 745 (49.3%) of total antipseudomonal β-lactam days. Between 2017 and 2021, the proportion of patients with suspected sepsis administered anti-MRSA or antipseudomonal therapy increased from 63.0% (82 731 of 131 275 patients) to 66.7% (101 003 of 151 435 patients) (adjusted OR [aOR] per year, 1.03; 95% CI, 1.03-1.04). However, resistant organisms were isolated in only 65 434 cases (7.3%) (30 617 gram-positive [3.4%], 38 844 gram-negative [4.3%]) and the proportion of patients who had any resistant organism decreased from 9.6% to 7.3% (aOR per year, 0.87; 95% CI, 0.87-0.88). Most patients with suspected sepsis treated with empiric anti-MRSA and/or antipseudomonal therapy had no resistant organisms (527 356 of 582 585 patients [90.5%]); this proportion increased from 88.0% in 2017 to 91.6% in 2021 (aOR per year, 1.12; 95% CI, 1.11-1.13). In this cross-sectional study of adults admitted to 241 US hospitals, empiric broad-spectrum antibiotic use for suspected community-onset sepsis accounted for half of all anti-MRSA or antipseudomonal therapy; the use of these types of antibiotics increased between 2017 and 2021 despite resistant organisms being isolated in less than 10% of patients treated with broad-spectrum agents.

The cardiovascular implications for exercise intolerance and dyspnoea in electronic cigarette users

Background: Electronic cigarettes (EC) have been proposed as a safe alternative to tobacco smoking, however, several studies have shown adverse health effects of EC. The chronic implications of EC on cardiorespiratory response and exertional dyspnoea are unknown. Aim: To examine the chronic effects of electronic cigarettes (EC) and tobacco cigarettes (TC) on resting vascular function, inflammatory markers, cardiorespiratory responses during exercise and exertional dyspnoea. Methodology: Three groups of young adults (16 each) with normal spirometry (EC users, TC smokers, and never-smokers [NS]) consented to participate in this study following institutional ethics approval. Participants performed spirometry and an incremental cardiopulmonary exercise test (CPET) 20W/2mins on an electronically braked cycle ergometer with blood lactate (BLa) measurements. Flow-mediated dilation (FMD%) of the brachial artery was assessed using Doppler ultrasonography. Venous blood samples were collected to assess inflammatory biomarkers associated with vascular function. Results: EC and TC groups had a lower peak work rate compared to NS controls (184 ± 30; 185 ± 35 vs. 228 ± 44 W, respectively; P &lt; 0.05). During submaximal exercise, EC and TC groups displayed higher ventilation (VE), higher ratings of dyspnoea and more intense leg fatigue compared to NS controls (e.g. 140 W, VE: 62 ± 10; 64 ± 12 vs. 54 ± 7 L/min, Dyspnoea: 5.0 ± 1.9; 6.1 ± 1.9 vs. 3.4 ± 1.7 Borg units, 6.1 ± 2.05; 7.0 ± 1.9 vs. 4.1 ± 2.1 Borg units, respectively; all P &lt; 0.05). The TC group displayed lower ventilatory efficiency (higher V̇E/V̇CO2) and higher blood lactate compared to NS during submaximal exercise (e.g. 140 W, V̇E/V̇CO2: 31.8 ± 5.6 vs. 28.2 ± 2.41, Blood lactate: 6.5 ± 2.4 vs. 4.3 ± 2.5 mmol/L, respectively; P &lt; 0.05 for both). Like the TC group, the EC group showed a trend for lower ventilatory efficiency and higher BLa during submaximal exercise, but they did not reach statistically significant differences compared to NS controls (P = 0.07 for both). FMD was significantly lower in EC and TC groups compared with NS controls (5.4 ± 2.4; 4.6 ± 2.9 vs. 7.9 ± 3.4%, respectively; P &lt; 0.05) and that was associated with elevated Thrombospondin-1 levels. Conclusion: EC and TC impair vascular function and cardiorespiratory responses to exercise and exertional dyspnoea similarly. EC has a detrimental impact on vascular function and exercise capacity and should not be recommended as a ‘healthier’ alternative to TC.

Kinematic and Physiological Analysis of Medieval Combat Sport Using Motion Analysis, Blood Lactate Measurement, and Heart Rate Monitoring: A Case Study.

Medieval combat sport is a form of mixed martial art in which combatants engage in fighting using offensive and defensive equipment while dressed in full armor. The sport is considered extremely taxing, making it nearly impossible to maintain the same level of performance. However, this form of sport has not been thoroughly analyzed, and its impact on human physical response is largely unknown. To address this gap, the study reported here aimed to introduce and test a procedure for analyzing human physical responses within the framework of the sport. To accomplish this, two experienced combatants were asked to engage in a series of strikes, performed in the form of a set duel simulating a professional fight competition. The kinematic aspect of the procedure was examined using motion analysis with the help of an IMU suit, while the physiological aspect was evaluated based on blood lactate levels and heart rate measurements. Furthermore, an ergometer test conducted in a laboratory setting aimed to determine the lactate threshold. The duel results showed noticeable decreases in the kinematic aspects of the strikes, such as the velocity of impact, and a dramatic rise in physiological aspects, such as heart rate and blood lactate levels. During the duel sets, the blood lactate surpassed the threshold level, and at the end, the heart rate exceeded the maximum age-related level. Practicing medieval combat sport has been shown to impose an extreme physical load on the bodies of combatants, noticeably affecting their performance levels.

Hyperlactataemia is a marker of reduced exercise capacity in heart failure with preserved ejection fraction.

Heart failure with preserved ejection fraction (HFpEF) is associated with an array of central and peripheral haemodynamic and metabolic changes. The exact pathogenesis of exercise limitation in HFpEF remains uncertain. Our aim was to compare lactate accumulation and central haemodynamic responses to exercise in patients with HFpEF, non-cardiac dyspnoea (NCD), and healthy volunteers. Right heart catheterization with mixed venous blood gas and lactate measurements was performed at rest and during symptom-limited supine exercise. Multivariable analyses were conducted to determine the relationship between haemodynamic and biochemical parameters and their association with exercise capacity. Of 362 subjects, 198 (55%) had HFpEF, 103 (28%) had NCD, and 61 (17%) were healthy volunteers. This included 139 (70%) females with HFpEF, 77 (75%) in NCD (P=0.41 HFpEF vs. NCD), and 31 (51%) in healthy volunteers (P<0.001 HFpEF vs. volunteers). The median age was 71 (65, 75) years in HFpEF, 66 (57, 72) years in NCD, and 49 (38, 65) years in healthy volunteers (HFpEF vs. NCD or volunteer, both P<0.001). Peak workload was lower in HFpEF compared with healthy volunteers [52W (interquartile range 31-73), 150W (125-175), P<0.001], but not NCD [53W (33, 75), P=0.85]. Exercise lactate indexed to workload was higher in HFpEF at 0.08mmol/L/W (0.05-0.11), 0.06mmol/L/W (0.05-0.08; P=0.016) in NCD, and 0.04mmol/L/W (0.03-0.05; P<0.001) in volunteers. Exercise cardiac index was 4.5L/min/m2 (3.7-5.5) in HFpEF, 5.2L/min/m2 (4.3-6.2; P<0.001) in NCD, and 9.1L/min/m2 (8.0-9.9; P<0.001) in volunteers. Oxygen delivery in HFpEF was lower at 1553mL/min (1175-1986) vs. 1758mL/min (1361-2282; P=0.024) in NCD and 3117mL/min (2667-3502; P<0.001) in the volunteer group during exercise. Predictors of higher exercise lactate levels in HFpEF following adjustment included female sex and chronic kidney disease (both P<0.001). HFpEF is associated with reduced exercise capacity secondary to both central and peripheral factors that alter oxygen utilization. This results in hyperlactataemia. In HFpEF, plasma lactate responses to exercise may be a marker of haemodynamic and cardiometabolic derangements and represent an important target for future potential therapies.

Effects of different work-to-rest ratios of high-intensity interval training on physical performance and physiological responses in male college judo athletes

ObjectiveThis study aimed to compare the effects of high-intensity interval training (HIIT) with work-to-rest ratios of 2:1 and 3:1 on physical performance and physiological responses in male college judo athletes. MethodsForty-eight male college judo athletes were randomly assigned to one of three groups. One used HIIT with a 2:1 work-to-rest ratio (2:1 group), another used HIIT with a 3:1 work-to-rest ratio (3:1 group), while a control group (CG) continued its regular training program as before. Subjects completed two training sessions per week for 6 weeks. The participants completed the Modified Agility T-test, 30-m sprint, medicine ball put, countermovement jump, 20-m multistage shuttle run test, and 30-s Wingate test before and after the training, and blood lactate measurements at 3, 5, 10, and 15 min after the 30-s Wingate test were taken before and after the training. ResultsThe 2:1 group (p = 0.010, d = 0.88 (large)) and 3:1 group (p = 0.002, d = 0.46 (small)) showed significant improvements in VO2max estimated by the 20-m multistage shuttle run test in comparison with pre-test. The 3:1 group had a significant difference in agility in comparison with the CG post-training (p = 0.004). Peak power (PP) and relative peak power (PP/kg) significantly improved in the 3:1 group (p < 0.05) compared to the pre-test. Blood lactate values at the fifth minute (p = 0.029) after the Wingate test in the 3:1 group were significantly decreased compared to the pre-test. ConclusionOur findings suggest that HIIT with the 3:1 and 2:1 work-to-rest ratios can improve aerobic power, and HIIT with a 3:1 work-to-rest ratio can improve absolute and relative peak power.

Phytochemistry and antifatigue activities of Carica papaya leaf from geothermal, coastal and urban areas, Indonesia.

Fatigue, a condition of lack of energy and motivation resulting in the feeling of extreme tiredness or exhaustion, is usually prevented and treated with ergogenic aids, such as in the form of nutritional supplements. Papaya (Carica papaya) may be a potential candidate for ergogenic aids, considering its healthy secondary metabolite properties and number of metabolite compounds that could be affected by the location where the plant growing. The aim of this study was to identify the phytochemicals of papaya leaves from three different locations: geothermal, coastal, and urban areas in Aceh province, Indonesia. Concentrations of papaya leaf with the highest number of secondary metabolite compounds were tested in rats to measure blood lactate acid concentrations after strenuous exercise. The number of chemical compounds identified from the three locations was 24 compounds; 23 compounds and 17 compounds, respectively. The highest concentration of chemical compounds that have antifatigue activity contained in all papaya leaf samples were neophytadiene, linolenic acid, gamma tocopherol, hexadecanoic acid, vitamin E, carpaine, octadecatrienoic acid, nor lean-12-ene, squalene, and phytol. Furthermore, most of the compounds' highest concentrations were found in papaya leaves from the coastal area and, therefore, tested on the animal model. Treatment was provided in 12 male rats with different doses of papaya powder supplements for 15 days. The results showed that lactic acid levels of rats received a dose of 400 mg/kg of papaya leaf extract reduced the lactic acid concentration (p=0.014) compared with the control group. This study highlights that papaya leaves from the coastal area have the most potential activities as ergogenic herbal aid and were able to reduce lactic acid levels in rats after strenuous exercise.

A 6-Week Ketogenic Diet Enhances the Phosphocreatine Energy System Contribution During Intermittent Sprints

Abstract Purpose Team sports often involve intermittent sprints. During these activities the Phosphocreatine-ATP buffer (ATP-PCr) signifies the major anaerobic energy substrate. While the effects of ketogenic diets (KD) on carbohydrate and fat metabolism during endurance exercise are widely reported, we explored keto-adaptation in ATP-PCr metabolism during intermittent sprint exercise. Methods Following a within-subject repeated measures design, 15 recreationally active participants (7 men, 8 women, aged 25.1 ± 6.4 years) performed cycle ergometer intermittent sprints (6 × 10 s sprints, 2 min recovery) with VO2 and blood lactate measurements for energy system calculations. These laboratory tests were performed in alternate weeks; First, twice at baseline on their habitual diet (HD) (35% CHO, 45% fat, 20% protein) and thereafter over a 6-week KD (7% CHO, 66% fat, 28% protein). Results Repeated measures ANOVA’s and Bonferroni tests revealed ATP-PCr derived energy increased significantly from HD to KD week 6 (+ 22.0 ± 43.15 J; P = 0.019; ES = 0.47). From HD to KD week 2, anaerobic glycolytic contribution lowered (− 14.4 ± 28.16 J; P = 0.031; ES = − 0.10) and peak blood [lactate] reduced significantly (− 2.92 ± 0.851 mmol; P = 0.004; ES = − 0.73). There was no statistically significant within-subject change in mean sprint power (P = 0.356). Conclusion The 6-week KD did not compromise intermittent sprint performance. The findings suggest that the ATP-PCr energy pathway may be a novel site of metabolic keto-adaptation. This, combined with the lowered blood [lactate] we observed, presents desirable metabolic adaptations for intermittent sprint sport athletes.

Post hospital admission blood lactate measurements are associated with mortality but not neurologic morbidity in children with cerebral malaria.

In children with cerebral malaria (CM) admission blood lactate has previously guided intravenous fluid therapy and been validated as a prognostic biomarker associated with death. The usefulness of post-admission measurements of blood lactate in children with CM is less clear. The strength of association between blood lactate and neurological sequelae in CM survivors, as well as the optimal duration of post-admission measurements of blood lactate to identify children at higher risk of adverse outcomes is unknown. A retrospective cohort study of 1674 Malawian children with CM hospitalized from 2000 to 2018 who had blood lactate measurements every 6h for the first 24h after admission was performed. The strength of association between admission lactate or values measured at any time point in the first 24h post-admission and outcomes (mortality and neurological morbidity in survivors) was estimated. The duration of time after admission that lactate remained a valid prognostic biomarker was assessed. When lactate is analysed as a continuous variable, children with CM who have higher values at admission have a 1.05-fold higher odds (95% CI 0.99-1.11) of death compared to those with lower lactate values. Children with higher blood lactate at 6h have 1.16-fold higher odds (95% CI 1.09-1.23) of death, compared to those with lower values. If lactate levels are dichotomized into hyperlactataemic (lactate > 5.0 mmol/L) or not, the strength of association between admission lactate and mortality increases (OR = 2.49, 95% CI 1.47-4.22). Blood lactate levels obtained after 18h post-admission are not associated with outcomes. Similarly, the change in lactate concentrations through time during the first 24h of hospital admission is not associated with outcomes. Blood lactate during hospitalization is not associated with adverse neurologic outcomes in CM survivors. In children with CM, blood lactate is associated with death but not neurologic morbidity in survivors. To comprehensively estimate prognosis, blood lactate in children with CM should be assessed at admission and for 18h afterwards.

Određivanje anaerobnog praga direktnim merenjem laktata u krvi bez protokola zagrevanja kod sportistkinja

Introduction: The anaerobic threshold (AT), determined by the direct blood lactate measurement, is of huge practical significance during the training test with the aim to estimate the training status of the female athletes. Aim: The aim of this research was to determine anaerobic threshold by direct blood lactate. Material and Methods: Academic research included 20 female subjects divided into four groups: I group - 10 non-trained subjects, who were not previously subjected to the warm up protocol, II group - 10 well-trained subjects who were not previously subjected to the warm up protocol of Conconi test. Results: Results obtained and presented in this paper show that AT, determined by the direct blood lactate measurement, is statistically significant (p &lt; 0,001) in higher values of the heart rate in well-trained subjects compared to the non-trained subjects not subjected. Conclusion: According to the aforementioned authors the Conconi test can be used nonetheless because of its easy administration with the precondition to provide the adequate interpretation in the assessment of the training capability in all sports activities.

Role of Blood Lactate Clearance in Predicting Outcomes among Septic Patients Admitted to the PICU: A Prospective Cohort Study

Introduction: A crucial metric for evaluating the effectiveness of microcirculation in septic shock is serum lactate. Lactate clearance within the first 24 hours of admission has predictive value for death in Paediatric Intensive Care Unit (PICU) admissions. Higher mortality was observed in septic patients who were unable to clear elevated admission lactate. Aim: To determine the admission lactate level and to investigate whether failure to clear elevated lactate in septic patients can prognosticate high PICU mortality. Materials and Methods: This prospective cohort study was conducted from August 2021 to July 2022 at PICU, Indira Gandhi Medical College, Shimla, Himachal Pradesh, India. A total of 75 children, aged two months to 18 years, admitted to the PICU for sepsis or septic shock, were enrolled in the study. The authors measured blood lactate at Intensive Care Unit (ICU) admission, at 6, 12, and 24 hours. Lactate clearance was calculated, and its association with mortality after 24 hours of PICU stay was measured using the Chi-square test. Results: Out of the total, 55 survived, comprising 31 males (41.3%) and 44 females (58.7%). When comparing admission blood lactate to lactate clearance &gt;10% at 6, 12, and 24 hours, there was no correlation between the two variables and mortality in PICU patients with sepsis. Conclusion: Lactate clearance in the first 24 hours of PICU stay was recommended as a parameter associated with the mortality rate among septic patients. However, the authors did not find any correlation.

The lactate response to a second bout of exercise is not reduced in a concurrent lower-limb exercise program

We aimed to evaluate the blood lactate level in response to two bouts of exercise. First, we hypothesized that blood lactate elevation in response to moderate-intensity aerobic exercise (MIAE) would be lower at the end of the second bout of MIAE than the first bout of MIAE. In this context, we also hypothesized that lactate accumulation at the end of resistance exercise (RE) would be reduced if MIAE is performed before RE (i.e., concurrent exercise; CE). If so, we hypothesized that the order of the CE (i.e., RE + MIAE vs. MIAE + RE) influences blood lactate kinetics. To test the hypotheses, forty-three healthy men participated in three studies. In study 1, 20 men (age 21 ± 2 years) performed two bouts of a 20-min MIAE separated by a 20-min rest interval. In study 2, 11 men (age 22 ± 1 years) performed RE only and CE (MIAE + RE; ARCE) with a 20-min rest interval in a crossover design. In study 3, 12 men (age 21 ± 2 years) performed both CEs, which were ARCE and RE + MIAE (RACE), with a 20-min rest interval in a crossover design. We measured blood lactate before and at the end of each exercise session. In study 1, the blood lactate response to the second bout of MIAE was lower than that of the first bout (P < 0.001, r = 0.68). However, the blood lactate response to the ARCE trial was not lower than the response to the RE trial in study 2 (P = 0.475, r = 0.22). The results of study 3 showed that the RACE and ARCE trials induced a similar lactate response (MIAE P = 0.423, r = 0.28; RE P = 0.766, d = 0.03). These observations indicate that whereas lactate accumulation might be diminished by a second bout of MIAE, a different type of exercise (i.e., aerobic/resistance) did not result in a diminished lactate accumulation in response to a second bout of exercise.

Abstract 370: Oral-Mucosal PCO 2 During Hemorrhagic Shock Closely Monitors Its Time Course, Severity, and Reversal Outperforming Blood Lactate Measurement

Objective: Oral-Mucosal PCO 2 (P OM CO 2 ) has been shown to closely correlate with the splanchnic mucosal PCO 2 and provide information on its microcirculation. We used a swine model of controlled hemorrhagic shock to assess the potential clinical relevance of monitoring P OM CO 2 to assess its clinical course, severity, and treatment effect. Methods: The study was performed on six male domestic pigs (37.9±1.4 kg). P OM CO 2 was measured using a non-invasive disposable sensor clipped to the cheek, developed by ExoStat Medical. Blood was removed over 120 minutes from the right atrium using a LabVIEW-controlled pump according to a mono-exponential decay curve modeling spontaneous bleeding and reinfused in 20 minutes observing the animal for a total of 180 minutes. Results: A total of 1,491±193 ml corresponding to 65.5% of the estimated blood volume were removed inducing the characteristic hemodynamic features of hemorrhagic shock including tachycardia, hypotension, reduced cardiac output, and reduced systemic oxygen delivery with increased systemic oxygen extraction. P OM CO 2 closely paralleled the time course of blood removal showing an early and steady increase from 85±5 mmHg at baseline to 144±32 mmHg after 120 minutes. Blood reinfusion rapidly reduced the P OM CO 2 to 130±17 mmHg after 20 minutes and 96±14 mmHg at the end of 180 minutes, coincident with reversal of hemorrhagic shock. P OM CO 2 also closely tracked changes in systemic oxygen extraction. Concurrent measurements of blood lactate demonstrated a slower increase during the hemorrhagic shock period (from 1.1±0.3 to 3.0±0.3 mmol/l) with further increase (not decrease) to 5.4±2.0 mmol/l after blood reinfusion, remaining at 4.3±0.8 mmol/l by the end of the 180-minute observation period. Conclusions: The study demonstrated capability of P OM CO 2 to closely and non-invasively track hemodynamic and metabolic changes occurring during hemorrhagic shock. P OM CO 2 outperformed blood lactate which exhibited a slower and delayed response. Thus, P OM CO 2 may provide a clinically practical and non-invasive means to monitor hemorrhagic shock assessing its severity, clinical course, and treatment effect.

Evaluation of Blood Lactate Concentrations as a Marker for Resuscitation and Prognosis in Patients with Major Burns

Background Severe burns require appropriate fluid management in the acute phase. A massive volume of intravenous fluid is usually required to ensure adequate end-organ perfusion. Lactate is a product of anaerobic metabolism. A high level of lactate in tissue is direct indication of tissue hypoxia. The correlation between serum lactate and clinical outcome has been well accepted in hemorrhagic and septic shock. However, studies on its use in predicting mortality and morbidity of major burn patients in particular is sparse. Early prediction of outcome in patients with major burn is very likely to aid suitable modification of management strategies. Objective To assess the role of serum lactate measurement as the predictor burn patient's outcome (survivors and non-survivors). Patients and Methods 30 patients with major burn (more than 20% of TBSA) were included. This includes operated/ non-operated patients. Of the 30 patients, 20 were males and 10 were females. All adult burned patients admitted within the first 24h post burn were included in the study. Patients admitted after 24h from the thermal injury, or those who were discharged or died 48h after admission were excluded. Results Serial blood lactate measures were better as a prognostic tool than isolated measure. Reduction or normalization of lactate levels 24 hours after admission was significantly associated with a higher probability of survival. This study confirms the prognostic value of serum lactate for mortality in patients with major burns as serial blood lactate measurements predict mortality in these patients. Conclusion Although many studies reiterate the importance of blood lactate and lactate clearance in predicting mortality in burn patients, the role of these markers in therapy titration is ambiguous. Overzealous fluid resuscitation can cause fluid overload and acute respiratory distress syndrome. little regional data are available to establish the importance of blood lactate. We have demonstrated the association of blood lactate in the first 36 hours of the burn injury with mortality. Further large multicenter prospective studies are required.

Health status of the red-billed tropicbird (Phaethon aethereus) determined by hematology, biochemistry, blood gases, and physical examination.

The red-billed tropicbird, Phaethon aethereus, is a species of seabird native to the Galápagos archipelago, and widely distributed across the neotropics. General health, blood chemistry, and haematology parameters have not been published for this species. Blood analyses were performed on samples drawn from 51 clinically healthy red-billed tropicbirds captured from their burrows at Islote Pitt on San Cristóbal Island in July, 2016 (21) and Daphne Major Island in June, 2017 (30). In the field, a point of care blood analyser (iSTAT) was used to obtain results for HCO3-, pH, pCO2, pO2, TCO2, iCa, Na, K, Cl, Hb, HCT, anion gap, creatinine, glucose and urea nitrogen. Additionally, a portable Lactate PlusTM analyser was used to measure blood lactate, and blood smears were also created in situ. The blood slides were used to estimate leukocyte counts and 100-cell differentials. Alongside these biochemistry and haematology parameters, average heart rate, respiratory rate, body temperature and scaled mass index (calculated from weight and a body measurement) were compared to determine the standard measurements for a healthy individual. The baseline data, and reference intervals reported in this paper are essential to detecting changes in the health of red-billed tropicbirds in the future.

Improved interference control after exercise with blood flow restriction and cooling is associated with but not mediated by increased lactate

BackgroundTo evaluate the effects of recumbent sprint interval exercise with and without blood flow restriction and body cooling on interference control and whether the changes in interference control can be explained by the changes in blood lactate. Methods85 participants (22 SD 3 years old) completed 1 familiarization visit and then 5 experimental visits in a randomized order: exercise only (Ex), exercise with blood flow restriction (ExB), exercise with cooling (ExC), and exercise with blood flow restriction and cooling (ExBC), and non-exercise control (Con). Measurements of blood lactate and the Stroop Color Word Test were performed before and after exercise. Each bout began with a 15-minute low-moderate intensity warm-up, followed by five 20-second “all out” sprints separated by 40 s of active recovery. Bayes Factors (BF10) quantified evidence for or against the null hypothesis. Within-subject mediation analysis quantified the indirect effect of changes in blood lactate (mediator) on the change in interference control (each exercise condition vs. Con). Results: Bayesian pairwise comparisons found that only ExC [σ: -0.37 (-0.59, -0.15)] and ExBC [σ: -0.3 (-0.53, -0.09)] produced changes in incongruent reaction time different from that of Con. There was also evidence that all exercise conditions increased blood lactate (BF10 = 8.65e+29 – 1.9e+32) and improved congruent reaction time (BF10 = 4.01 – 15.371) compared to that of Con. There was no evidence to show that changes in lactate mediated the change in incongruent reaction time. ConclusionsBoth exercise with body cooling and when body cooling was combined with blood flow restriction presented favorable changes in incongruent reaction time (a marker of interference control), which might not be explained by the changes in systemic blood lactate concentration.

Elevated blood lactate in COPD exacerbations associates with adverse clinical outcomes and signals excessive treatment with β2 -agonists.

Raised blood lactate secondary to high dose β2 -agonist treatment has been reported in asthma exacerbations but has not been investigated during acute exacerbations of COPD (AECOPD). We explored associations of blood lactate measurements with disease outcomes and β2 -agonist treatments during AECOPD. Retrospective (n = 199) and prospective studies (n = 142) of patients hospitalized with AECOPD were conducted. The retrospective cohort was identified via medical records and the prospective cohort was recruited during hospitalization for AECOPD. Baseline demographics, comorbidities, β2 -agonist treatment, biochemical measurements and clinical outcomes were compared between patients with normal (≤2.0 mmol/L) versus elevated lactate (>2.0 mmol/L). Regression analyses examined associations of lactate measurements with β2 -agonist dosages. Demographic data and comorbidities were similar between high versus normal lactate groups in both cohorts. The populations were elderly (mean >70 years), predominantly male (>60%) with reduced FEV1 (%) 48.2 ± 19 (prospective cohort). Lactate was elevated in approximately 50% of patients during AECOPD and not related to evidence of sepsis. In the prospective cohort, patients with high lactate had more tachypnoea, tachycardia, acidosis and hyperglycaemia (p < 0.05) and received more non-invasive ventilation (37% vs. 9.7%, p < 0.001, prospective cohort). There was a trend to longer hospitalization (6 vs. 5 days, p = 0.06, prospective cohort). Higher cumulative β2 -agonist dosages were linked to elevated lactate levels (OR 1.04, p = 0.01). Elevated lactate during AECOPD was common, unrelated to sepsis and correlated with high cumulative doses of β2 -agonists. Raised lactate may indicate excessive β2 -agonist treatment and should now be investigated as a possible biomarker.