Higher Blood Lactate Research Articles

Performance during a strenuous swimming session is associated with high blood lactate: pyruvate ratio and hypoglycemia in fasted rats.

The aim of this study was to investigate the effect of lactatemia elevation and glycemia reduction on strenuous swimming performance in fasted rats. Three rats were placed in a swimming tank at the same time. The first rat was removed immediately (control group) and the remaining ones were submitted to a strenuous swimming session. After the second rat was exhausted (Exh group), the third one was immediately removed from the water (Exe group). According to the period of time required for exhaustion, the rats were divided into four groups: low performance (3–7 min), low-intermediary performance (8–12 min), high-intermediary performance (13–17 min), and high performance (18–22 min). All rats were removed from the swimming tanks and immediately killed by decapitation for blood collection or anesthetized for liver perfusion experiments. Blood glucose, lactate, and pyruvate concentrations, blood lactate/pyruvate ratio, and liver lactate uptake and its conversion to glucose were evaluated. Exhaustion in low and low-intermediary performance were better associated with higher lactate/pyruvate ratio. On the other hand, exhaustion in high-intermediary and high performance was better associated with hypoglycemia. Lactate uptake and glucose production from lactate in livers from the Exe and Exh groups were maintained. We concluded that there is a time sequence in the participation of lactate/pyruvate ratio and hypoglycemia in performance during an acute strenuous swimming section in fasted rats. The liver had an important participation in preventing hyperlactatemia and hypoglycemia during swimming through lactate uptake and its conversion to glucose.

The effect of time trial position on physiological variables in elite cycling.

Introduction Improving time trial performance can be achieved by cycling with an optimized aerodynamic position 1 . However, although reducing the cyclist’s frontal area will reduce the air resistance that must be overcome, a time trial position has significant flexibility requirements and some positions can potentially impair the ability to produce external power 2 . Physiological effects of using an aerodynamic position compared to an upright one, such as increased oxygen cost, have been shown in recreational cyclists 2 . In competitive cyclists, on the other hand, no difference between using the drops compared to an upright position has been shown 3 . However, less is known about the effect of these position changes in cyclists at the highest level, as well as the effect of using a too low position. Therefore, the purpose of the present pilot study was to investigate the effect of different time trial positions on physiological variables in elite competitive cyclists. Methods Three male junior elite cyclists participated in the study. All participants were competitive at the national level and participated in the national championships. Three positions on the bike were used: a high and low time trial position and an upright position with straight arms holding on the base bars. Each bout lasted 5 minutes, was separated by 4 minutes of rest and the work rate was set relative to the individual level of each cyclist, at ~90% of their 20-min peak power. All cycling was done at freely chosen cadences on a time trial specific bike mounted on a trainer (Computrainer Lab TM , Race Mate, Seattle, WA, USA). Results Average work rate during the cycling bouts was 339±16W (4.7±0.2 W/kg). The physiological response of cycling in the three positions is presented in Figure 1. The lowest time trial position resulted in higher blood lactate levels, higher oxygen consumption and lower gross efficiency compared to the high time trial position. For the upright position, oxygen consumption and gross efficiency were comparable to the lowest time trial position. However, blood lactate during the upright position was the lowest measured across all conditions. Discussion The main finding of the present study was that using a very low time trial position led to decreased gross efficiency and increased oxygen consumption and blood lactate compared to the high time trial position. The upright position led to an increased oxygen consumption compared to the time trial positions, but blood lactate was lower, which could indicate an increased energetic cost of maintaining an upright position with the arms. The reduced gross efficiency and increased blood lactate further indicate that in elite level junior cyclists, having a too low time trial position may be physiologically unfavourable.

Prognostic implications of blood lactate concentrations after cardiac arrest: a retrospective study

BackgroundElevated lactate concentration has been associated with increased mortality after out-of-hospital cardiac arrest (CA). We investigated the variables associated with high blood lactate concentrations and explored the relationship between blood lactate and neurological outcome in this setting.MethodsThis was a retrospective analysis of an institutional database that included all adult (> 18 years) patients admitted to a multidisciplinary Department of Intensive Care between January 2009 and January 2013 after resuscitation from CA. Blood lactate concentrations were collected at hospital admission and 6, 12, 24 and 48 h thereafter. Neurological outcome was evaluated 3 months post-CA using the Cerebral Performance Category (CPC) score: a CPC of 3–5 was used to define a poor outcome.ResultsOf the 236 patients included, 162 (69%) had a poor outcome. On admission, median lactate concentrations (5.3[2.9–9.0] vs. 2.5[1.5–5.5], p < 0.001) and cardiovascular sequential organ failure assessment (cSOFA) score (3[0–4] vs. 0[0–3], p = 0.003) were higher in patients with poor than in those with favourable outcomes. Lactate concentrations were higher in patients with poor outcomes at all time points. Lactate concentrations were similar in patients with out-of-hospital and in-hospital CA at all time points. After adjustment, high admission lactate was independently associated with a poor neurological outcome (OR 1.18, 95% CI 1.08–1.30; p < 0.001). In multivariable analysis, use of vasopressors and high PaO2 on admission, longer time to return of spontaneous circulation and altered renal function were associated with high admission lactate concentrations.ConclusionsHigh lactate concentrations on admission were an independent predictor of poor neurological recovery post-CA, but the time course was not related to outcome. Prolonged resuscitation, use of vasopressors, high PaO2 and altered renal function were predictors of high lactate concentrations.

Abstract 445: Efficient tumorigenesis after genetic dissociation of glycolysis and the TCA cycle

Abstract Virtually all tumors undergo some form of metabolic re-programming to match anabolic needs with energy supply. The best-known form of this is the Warburg effect by which tumors become more reliant on glycolysis over mitochondrial oxidative phosphorylation, even when their oxygen supply is abundant. Nonetheless, mitochondria retain some residual activity in order to provide both ATP and critical metabolic building blocks and other substrates for processes such as lipid biosynthesis and protein acetylation. The pyruvate dehydrogenase (PDH) complex (PDC) is the main enzymatic link between glycolysis and the TCA cycle and irreversibly converts the end-stage glycolytic product pyruvate into the critical TCA substrate, acetyl-coenzyme A (AcCoA). In a mouse model of the pediatric liver cancer hepatoblastoma (HB), we recently showed PDH to be highly up-regulated, despite reduced mitochondrial function. We postulated that this might represent a response to pyruvate depletion due to upstream shunting of glycolytic intermediates into anabolic pathways. To test this idea, we examined in vivo tumorigenesis in mice bearing a hepatocyte-specific conditional knockout of the pdha1 subunit (KO mice). The survival of these mice was marginally longer than the wild-type (WT) controls, although tumor sizes at time of death were ~20% smaller. KO mice expressed virtually no PDH (and hence no PDC activity) and had high blood lactate levels. This suggested that they succumbed with smaller tumors as a result of severe lactic acidosis that could not be corrected by hyperventilation due to respiratory compromise by the large HBs that restricted lung volumes. This was supported by studies performed in a modified form of this model in which only tumors were PDC deficient whereas the surrounding liver parenchyma was not. These mice now survived longer than did their WT counterparts and their tumors reached comparable sizes. They also had lower lactate levels than the pan-KO mice. Oxygen consumption rates of WT and KO tumors were similar yet were lower than those of normal livers. Rates of fatty acid β-oxidation by WT and KO tumors were also lower than those of liver, indicating that both types of tumors preferentially divert fatty acids into membrane synthesis rather than toward supplying AcCoA. Taken together, these findings demonstrate the remarkable capacity for nearly normal HB pathogenesis despite the severing of glycolysis from the TCA cycle. Citation Format: Laura E. Jackson, Sucheta Kulkarni, Huabo Wang, Jie Lu, Sivakama Bharathi, Radha Uppala, Mulchand S. Patel, Eric S. Goetzman, Edward V. Prochownik. Efficient tumorigenesis after genetic dissociation of glycolysis and the TCA cycle [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 445. doi:10.1158/1538-7445.AM2017-445

A multicenter confirmatory study about precision and practicability of Sepsis-3

To clinically validate the precision of diagnostic Sepsis-3 criteria, and to guide and generalize its clinical application. A multicenter retrospective observational study was conducted. The patients admitted to intensive care unit (ICU) of 6 tertiary hospitals in Zhejiang Province from January to June 2015 were enrolled, and the patients satisfying the diagnostic criteria of Sepsis-2 and Sepsis-3 were screened. Population characteristics between the patients satisfying two editions were compared, and the diagnosis accuracy rate in different degree hospitals were investigated. According to the doctor's diagnosis, the patients who met the criteria of Sepsis-2 were divided into diagnosis group and non-diagnosis group, and the factors influencing the diagnosis of sepsis were analyzed by logistic regression. The patients meeting Sepsis-2 but no meeting Sepsis-3 were served as exclusion group, and those meeting Sepsis-2 and Sepsis-3 were served as enroll group, and the characteristics of patients between the two groups were compared. Receiver operating characteristic (ROC) curve was plotted to evaluate the predictive value of systemic inflammatory response syndrome (SIRS) score, sepsis-related quick sequential organ failure assessment (qSOFA) and sequential organ failure assessment (SOFA) on death, and whether the consistency of qSOFA and SOFA would affect the sensitivity of definition. The patients meeting Sepsis-2 were divided into non-survived group and survived group, and the factors associated with death were analyzed by logistic regression. Finally, 1 423 patients were enrolled, 3 patients with age < 18 years and 19 patients with missing data were excluded. There were 363 patients and 329 patients met Sepsis-2 and Sepsis-3, respectively. No significant differences were found in population characteristics between the groups of Sepsis-2 and Sepsis-3 (all P > 0.05) except for acute physiology and chronic health evaluation II (APACHE II) score [19.10 (8.00) vs. 20.28 (8.00), P < 0.05]. It was shown on the clinical data analysis of the hospitals that the patients meeting Sepsis-2 and Sepsis-3 in hospital 3 had the highest 28-day mortality (60.4% and 60.0%) with the lowest rate of diagnosis (0). While in the hospital 1, the patients had the lowest 28-day mortality (22.9% and 27.2%), and the rate of diagnosis was 19.5%. Interestingly, the patients in hospital 4 had the highest diagnosis rate of sepsis (44.8%), but 28-day mortality was both 58.6%. It was shown by logistic regression analysis that the patients with old age [odds ratio (OR) = 0.970, P = 0.021], high blood lactate (OR = 0.443, P = 0.004), high blood pressure (OR = 0.957, P = 0.009) and low oxygenation index (OR = 1.004, P = 0.024) were easy to neglect diagnosis. Compared with Sepsis-3 exclude group, the patients in Sepsis-3 enroll group were older [years: 68.52 (26.00) vs. 53.75 (18.00), P < 0.01] with higher APACHEII score [20.38 (8.00) vs. 7.72 (6.00), P < 0.01], higher blood lactate [mmol/L: 3.45 (3.00) vs. 1.95 (1.20), P > 0.05], longer length of ICU stay [days: 22.42 (22.00) vs. 15.13 (16.00), P < 0.01], and higher 28-day mortality [45.29% (149/329) vs. 14.71% (5/34), P < 0.01], indicating that the diagnostic efficiency of Sepsis-2 was low, the diagnostic specificity of Sepsis-3 was high, and the prognosis of Sepsis-3 patients was worse. It was shown by ROC curve analysis that the prognostic value of SIRS, qSOFA and SOFA to mortality was gradually increased [area under ROC curve (AUC) was 0.567, 0.597, 0.683, respectively], but the prognostic value were all low. Comparing patients meeting qSOFA and (or) SOFA in Sepsis-2, significant differences were found in APACHE II score [17.55 (7.00) vs. 23.24 (8.00)] and 28-day mortality [38.75% (31/80) vs. 58.59% (75/128), both P < 0.01]. The patients who just met the qSOFA or SOFA, their 28-day mortality was up to 38.75%, suggesting that qSOFA should not be ignored. Compared with survived group, the patients in survived group were older with higher APACHE II score and shorter length of ICU stay (all P < 0.05). It was shown by logistic regression analysis that APACHE II score (OR = 1.199, P = 0.000) and length of ICU stay (OR = 0.949, P = 0.000) were related with death. Patients satisfied Sepsis-3 were easier to develop more organ failure, Sepsis-3 and higher death prediction than Sepsis-2 and higher diagnosis specificity, but data shows that there is extra room for improvement.

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.

Refractory septic shock in children: a European Society of Paediatric and Neonatal Intensive Care definition.

PurposeAlthough overall paediatric septic shock mortality is decreasing, refractory septic shock (RSS) is still associated with high mortality. A definition for RSS is urgently needed to facilitate earlier identification and treatment. We aim to establish a European society of paediatric and neonatal intensive care (ESPNIC) experts’ definition of paediatric RSS.MethodsWe conducted a two-round Delphi study followed by an observational multicentre retrospective study. One hundred and fourteen paediatric intensivists answered a clinical case-based, two-round Delphi survey, identifying clinical items consistent with RSS. Multivariate analysis of these items in a development single-centre cohort (70 patients, 30 % mortality) facilitated development of RSS definitions based on either a bedside or computed severity score. Both scores were subsequently tested in a validation cohort (six centres, 424 patients, 11.6 % mortality).ResultsFrom the Delphi process, the draft definition included evidence of myocardial dysfunction and high blood lactate levels despite high vasopressor treatment. When assessed in the development population, each item was independently associated with the need for extracorporeal life support (ECLS) or death. Resultant bedside and computed septic shock scores had high discriminative power against the need for ECLS or death, with areas under the receiver operating characteristics curve of 0.920 (95 % CI 0.89–0.94), and 0.956 (95 % CI 0.93–0.97), respectively. RSS defined by a bedside score equal to or higher than 2 and a computed score equal to or higher than 3.5 was associated with a significant increase in mortality.ConclusionsThis ESPNIC definition of RSS accurately identifies children with the most severe form of septic shock.Electronic supplementary materialThe online version of this article (doi:10.1007/s00134-016-4574-2) contains supplementary material, which is available to authorized users.

Correlation of Mycoplasma pneumoniae resistance gene detection and refractory Mycoplasma pneumoniae pneumonia

Objective To understand the correlation of gene detection of Mycoplasma pneumoniae and clinical refractory Mycoplasma pneumoniae pneumonia. Methods (1)For children with Mycoplasma pneumoniae pneumonia in our hospital with serum Mycoplasma pneumoniae antibody positive, we collected the pharyngeal swab specimens over the same period, applied nested PCR to amplify 23SrRNA gene and undergoing electrophoresis and find out 97 cases of both positive, conducted DNA sequencing analysis of macrolide resistant gene to isolate the mutants, compared clinical manifestations of drug-resistance gene group with no drug-resistance gene mutation group.(2)Ninety-seven cases of mycoplasma pneumonia(MPP)patients were devided into the general MPP group(68 cases)and refractory MPP group(29 cases), retrospectively analyzed clinical manifestation, laboratory examination and differences of imaging performance.Multivariate logistic regression analysis for the performance of refractory Mycoplasma pneumoniae pneumonia was carried out to examine whether there is relevance between the mutant of drug-resisting gene and refractory Mycoplasma pneumonia. Results (1)Seventeen of 97 cases(17.5%)were found out without mutations, the other 80 cases(82.5%)exist drug-resistance gene mutations.(2)Mutation of drug-resistance gene group showed high CRP values, heating time, hospitalization time, macrolide drug application time, application of macrolides fever time and longer cough, by statistical analysis with statistical significance, higher incidence of lobar pneumonia.(3)Compared to general MPP group, refractory MPP group showed high peripheral blood neutrophil percentage percentage, CRP, calcitonin)and lactate dehydrogenase(LDH)values, heating time, hospitalization time, macrolide drug application time, application of macrolides fever time and longer cough.There was significant difference(P<0.05); macrocyclic lactones drug application time and resistance gene mutation and refractory Mycoplasma pneumonia were correlated. Conclusion MPP drug-resistant genes are widespread.Drug resistance gene mutations group shows long clinical symptoms duration, slow recovery rate, higher CRP value, higher rates of lobar pneumonia.Compared with ordinary MPP group, there are higher drug resistance mutation rate, inflammatory indexes and lactate dehydrogenase value, large ring lactone class drugs after a longer time of cough and fever in RMPP group.Drug application time and resistant gene mutations are associated with RMPP. Key words: Refractory Mycoplasma pneumoniae pneumonia; Drug resistance; 23SrRNA gene; Mutation

Prognostic values of blood pH and lactate levels in patients resuscitated from out-of-hospital cardiac arrest.

AimEarly prediction of prognosis after out‐of‐hospital cardiac arrest (OHCA) remains difficult. High blood lactate or low pH levels may be associated with poor prognosis in OHCA patients, but these associations remain controversial. We compared blood lactate and pH levels in OHCA patients transferred to our hospital to measure their prognostic performance.MethodsWe investigated the associations between blood lactate and pH levels on admission and neurological outcomes in 372 OHCA patients who had a return of spontaneous circulation.ResultsOf the 372 OHCA patients, 31 had a favorable neurological outcome. Blood lactate levels were lower in patients with a favorable outcome than in those with an unfavorable outcome, but this difference did not reach statistical significance (82 ± 49 vs. 96 ± 41 mg/dL). However, pH levels were significantly higher in patients with a favorable outcome than in those with an unfavorable outcome (7.26 ± 0.16 vs. 6.93 ± 0.19, P < 0.001). The relative cumulative frequency distribution curve analysis showed the optimal cut‐off points of lactate and pH to be approximately 80 mg/dL and 7.05, respectively. Sensitivity and specificity to predict a favorable outcome were 61% and 64% for lactate <80 mg/dL and 84% and 80% for pH >7.05, respectively. Areas under receiver–operating characteristic curves were significantly larger for pH than for lactate levels (P < 0.001). In multivariate analysis, pH >7.05 was an independent predictor for a favorable outcome.ConclusionAfter OHCA, patients with a favorable outcome had lower lactate and higher pH levels than those with an unfavorable outcome, but pH level was a much better predictor for neurological outcome than lactate levels.

Serum lactate level as a useful predictor of clinical outcome after surgery: an unfulfilled potential?

Serum lactate level as a useful predictor of clinical outcome after surgery: an unfulfilled potential?

ENDOCRINE AND METABOLIC ALTERATIONS MAY UNDERLIE MORTALITY OF SEVERE SEPSIS AND SEPTIC SHOCK PATIENTS ADMITTED TO ICU.

The study evaluated endocrinal and metabolic response to sepsis and its applicability for the prediction of outcome of septic patients. Patients were 39 adult with severe infections and within 24 h after onset or suspected clinical tissue hypoperfusion. At enrollment patients were evaluated for acute physiology and chronic health evaluation II score (APACHE II) and Glasgow Coma Scale (GCS). Global hemodynamic parameters including systolic blood pressure (SBP), heart rate (HR) and central venous pressure (CVP) were recorded and monitored. All patients were managed at ICU due to Surviving Sepsis Campaign guidelines. ELISA estimated serum copeptin, macrophage migration inhibitory factor (MIF) and total cortisol (TC) and blood lactate levels. Study outcome was survival rate via 28 days (28-D SR) and best predictor for it. The results showed that 22 patients passed total hospital stay uneventfully for a total survival rate of 56.4%. Seventeen patients died; 10 during ICU stay and 7 during word stay. At admission serum markers levels were significantly higher in survivors and non-survivors compared to controls and in non-survivors compared to survivors. Survival showed negative significant correlation with age, high blood lactate and serum copeptin, TC and MIF levels. Survival showed positive significant correlation with SBP, CVP and urine output. ROC curve and Regression analyses defined high at admission serum copeptin and blood lactate levels as significant predictors for mortality of septic patients.

Effects of an Exhaustive Exercise on Motor Skill Learning and on the Excitability of Primary Motor Cortex and Supplementary Motor Area.

We examined, on 28 healthy adult subjects, the possible correlations of an exhaustive exercise, and the consequent high blood lactate levels, on immediate (explicit) and delayed (implicit) motor execution of sequential finger movements (cognitive task). Moreover, we determined with transcranial magnetic stimulation whether changes in motor performance are associated with variations in excitability of primary motor area (M1) and supplementary motor area (SMA). We observed that, after an acute exhaustive exercise, the large increase of blood lactate is associated with a significant worsening of both explicit and implicit sequential visuomotor task paradigms, without gender differences. We also found that, at the end of the exhaustive exercise, there is a change of excitability in both M1 and SMA. In particular, the excitability of M1 was increased whereas that of SMA decreased and, also in this case, without gender differences. These results support the idea that an increase of blood lactate after an exhaustive exercise appears to have a protective effect at level of primary cortical areas (as M1), although at the expense of efficiency of adjacent cortical regions (as SMA).

Clinical Cases of Leukoencephalopathy with Predominant Lesion of the Brain Stem, Spinal Cord and High Blood Lactate in the MR Spectroscopy (Mitochondrial Aspartyl-tRNASynthetase Deficiency)

Leukoencephalopathy with predominant lesion of the brain stem, spinal cord and high blood lactate in the MR spectroscopy is a hereditary disease characterized by slowly progressing cerebellar, pyramidal disorders, disorders involving the lesion of posterior columns of the spinal cord and highly specific changes according to the data of MRI and magnetic resonanse spectroscopy of the brain and spinal cord. This disease is one of nuclear inherited mitochondrial encephalomyopathies, caused by mutations in the DARS2 gene and characterized by mitochondrial aspartyl-tRNA-synthetase deficiency. This article presents the record of the disease description, its genetic basis, clinical features and diagnostic criteria. The article describes two clinical cases of the disease in 9-year and 17-year old girls.

Effectiveness of predicting outcome in septic shock in critically ill children by assessing serum lactate levels

Background and Aims: Hyperlactatemia at the time of admission is a documented risk factor for mortality in critically ill adult patients. However, the significance of lactate measurement at admission for mortality in critically ill children remains uncertain. This study evaluated the predictive value of blood lactate levels at the time of admission and determined the cut-off values for predicting in-hospital mortality in the critically ill children. Materials and Methods: A total of 60 children with diagnosis of sepsis admitted to PICU of a tertiary care hospital were included in the study. PRISM III score and demographic characteristics of all children were recorded. Serum lactate levels were measured at 0-3, 12 and 24 h of PICU admission. The outcome like survival or death was correlated with serum lactate levels. Results: Septic shock was the most common type of shock and had highest mortality. Lactate levels were significantly higher in non survivors in comparison to survivors. A lactate value of more than 5 mmol/l at 0-3, 12 and 24h of PICU admission had increased mortality. Conclusions: A high blood lactate level at admission is independently associated with higher in-hospital mortality in the critically ill children.

Evaluation of Snowboard Deck through Physiological Analysis: Blood Lactate Concentration

Objectives: With the need for development of domestic sports products in Korea, this study proposed to present a technical evaluation to verify effects of prototype decks on physiological characteristics. Methods/Statistical Analysis: Five slope style snowboarders were tested in an advanced slope style course which was 420 m in length with an average pitch of 20° to maximum pitch of 30°. Double blind test was performed on prototype decks of 1st edition (B5) and 2nd edition (B1, B2, B3). A comparative physiological analysis of blood lactate concentration level while snowboarding on the course with different decks was analyzed. Findings: There was a statistically significant difference observed among different prototype decks (p<.05). The results of the post hoc test showed higher blood lactate concentration in B5, B2, B3 than B1 deck. Furthermore, significant difference was observed in the time period of accumulation (p<.01). When comparing difference in percent change to the resting state, 32.07% increment was observed in B1, B2 and B3 decks than B5. After exercise, B1 increased by 49.82%, B3 increased by 18.45% than B5, while B2 decreased by 3.32% than B5. According to the result obtained from our study, the lactate level of subjects while riding on the 2nd edition B3 deck was found to be most appropriate than 1st edition B5 prototype. Applications / Improvement: The results and the method from the study can be further applied to set a standard for physiological basis of performance analysis for various sporting equipment.

Use of venous-to-arterial carbon dioxide tension difference to guide resuscitation therapy in septic shock.

The mixed venous-to-arterial carbon dioxide (CO2) tension difference [P (v-a) CO2] is the difference between carbon dioxide tension (PCO2) in mixed venous blood (sampled from a pulmonary artery catheter) and the PCO2 in arterial blood. P (v-a) CO2 depends on the cardiac output and the global CO2 production, and on the complex relationship between PCO2 and CO2 content. Experimental and clinical studies support the evidence that P (v-a) CO2 cannot serve as an indicator of tissue hypoxia, and should be regarded as an indicator of the adequacy of venous blood to wash out the total CO2 generated by the peripheral tissues. P (v-a) CO2 can be replaced by the central venous-to-arterial CO2 difference (ΔPCO2), which is calculated from simultaneous sampling of central venous blood from a central vein catheter and arterial blood and, therefore, more easy to obtain at the bedside. Determining the ΔPCO2 during the resuscitation of septic shock patients might be useful when deciding when to continue resuscitation despite a central venous oxygen saturation (ScvO2) > 70% associated with elevated blood lactate levels. Because high blood lactate levels is not a discriminatory factor in determining the source of that stress, an increased ΔPCO2 (> 6 mmHg) could be used to identify patients who still remain inadequately resuscitated. Monitoring the ΔPCO2 from the beginning of the reanimation of septic shock patients might be a valuable means to evaluate the adequacy of cardiac output in tissue perfusion and, thus, guiding the therapy. In this respect, it can aid to titrate inotropes to adjust oxygen delivery to CO2 production, or to choose between hemoglobin correction or fluid/inotrope infusion in patients with a too low ScvO2 related to metabolic demand. The combination of P (v-a) CO2 or ΔPCO2 with oxygen-derived parameters through the calculation of the P (v-a) CO2 or ΔPCO2/arteriovenous oxygen content difference ratio can detect the presence of global anaerobic metabolism.

Hyperlactatemia in patients undergoing adult cardiac surgery under cardiopulmonary bypass: Causative factors and its effect on surgical outcome.

Objectives of the Study:To identify the factors causing high lactate levels in patients undergoing cardiac surgery under cardiopulmonary bypass (CPB) and to assess the association between high blood lactate levels and postoperative morbidity and mortality.Methods:A retrospective observational study including 370 patients who underwent cardiac surgeries under cardiopulmonary bypass. The patients were divided into 2 groups based on serum lactate levels; those with serum lactate levels greater than or equal to 4 mmol/L considered as hyperlactatemia and those with serum lactate levels less than 4 mmol/L. Blood lactate samples were collected intraoperatively and postoperatively in the ICU. Preoperative and intraoperative risk factors for hyperlactatemia were identified using the highest intraoperative value of lactate. The postoperative morbidity and mortality associated with hyperlactatemia was studied using the overall (intraoperative and postoperative values) peak lactate levels. Preoperative clinical data, perioperative events and postoperative morbidity and mortality were recorded.Results:Intraoperative peak blood lactate levels of 4.0 mmol/L or more were present in 158 patients (42.7%). Females had higher peak intra operative lactate levels (P = 0.011). There was significant correlation between CPB time (Pearson correlation coefficient r = 0.024; P = 0.003) and aortic cross clamp time (r = 0.02, P = 0.007) with peak intraoperative blood lactate levels. Patients with hyperlactatemia had significantly higher rate of postoperative morbidity like atrial fibrillation (19.9% vs. 5.3%; P = 0.004), prolonged requirement of inotropes (34% vs. 11.8%; P = 0.001), longer stay in the ICU (P = 0.013) and hospital (P = 0.001).Conclusions:Hyperlactatemia had significant association with post-operative morbidity. Detection of hyperlactatemia in the perioperative period should be considered as an indicator of inadequate tissue oxygen delivery and must be aggressively corrected.

Long-Term β-Blocker Therapy Decreases Blood Lactate Concentration in Severely Septic Patients*

Measurement of blood lactate concentration in the early management of sepsis is an important step in severity assessment. High blood lactate levels in the early phase of sepsis have classically been thought to be related to tissue hypoxia, but other factors could intervene. We hypothesized that the activation of glycolysis through β-adrenergic stimulation by endogenous catecholamines plays an important role in lactate production and that long-term β-blocker therapy could affect the lactate concentration in patients with severe sepsis and septic shock. Retrospective cohort study. Emergency department. Two hundred sixty patients with severe sepsis or septic shock were included. Twenty-five percent were previously treated with β-blockers. None. We recorded initial vital signs, the source of infection, mortality at 28 days, blood lactate concentration, and Predisposition Insult Response of Organ failure and Sequential Organ Failure Assessment scores using an electronic database. Blood lactate concentration was significantly lower in patients previously treated with β-blockers (3.9 ± 2.3 mmol/L vs 5.6 ± 3.6 mmol/L; p < 0.001). This difference was still significant after controlling for mortality (p < 0.005), for the level of the Predisposition Insult Response of Organ failure (p < 0.05) and Sequential Organ Failure Assessment (p < 0.05) scores, and for the source of infection (p < 0.05). Nearly four times more patients treated with β-blockers had normal blood lactate levels (p< 0.001). Only two factors were significantly and independently associated with normal blood lactate concentration during severe sepsis and septic shock: survival (p = 0.03) and β-blocker therapy (p = 0.01). Long-term β-blocker therapy decreases blood lactate concentration of severely ill septic patients at presentation. We conclude that the use of blood lactate measurement as a triage tool in the initial assessment of septic patients with β-blocker therapy may underestimate the severity of the sepsis.

Influence of intravenous thiamine supplementation on blood lactate concentration prior to cardiac surgery: A double-blinded, randomised controlled pilot study.

Stress related to surgery and critical illness depletes thiamine, essential in energy metabolism, and might result in high blood lactate concentrations and higher mortality. We hypothesised that thiamine supplementation would increase blood concentration of thiamine and reduce blood lactate concentration postoperatively. Moreover, we aimed to identify the prevalence of, and risk factors for, high blood lactate concentrations. This was a double-blind, randomised controlled pilot study from February to July 2012 including 30 patients scheduled for cardiac surgery with cardiopulmonary bypass. Patients were assigned randomly to receive thiamine (300 mg in 0.9% Normal saline solution) or placebo (0.9% Normal saline) preoperatively. One arterial blood sample was taken preoperatively and another postoperatively to measure thiamine concentration, and multiple samples were taken during surgery and ICU stay to determine lactate concentrations. Twenty-four hour urine samples were collected to measure urinary thiamine concentration. Preoperatively, we assessed extracellular mass to body cell mass ratio (ECM/BCM). The mean (SD) age of the patients was 58 (12) years, 73% were overweight, 10% were malnourished and the prevalence of thiamine deficiency was 10%. Patients in the thiamine group had significantly higher blood thiamine concentrations 2 days postoperatively [805.2 ± 289.8 ng g(-1) haemoglobin (Hb)] than those in the placebo group (591.2 ± 100.7 ng g(-1) Hb, P < 0.01). The mean blood lactate concentration changed significantly over time, but did not differ significantly between the groups. Patients with ECM/BCM more than 1 had higher lactate concentrations on admission to ICU than those with ECM/BCM less than 1 (2.1 ± 0.7 vs. 1.7 ± 0.6, P = 0.09) and were at a significantly greater risk of having a higher lactate concentration on ICU admission [odds ratio (OR) 13.5, 95% confidence interval (95% CI) 1.0 to 179.4, P < 0.05]. On the basis of these results, a sample size calculation for a larger study has been facilitated. Thiamine supplementation caused normalisation of blood and urine concentrations postoperatively but without a significant reduction in lactate concentration or clinical outcome. Body composition played an important role in lactate formation. Further research focusing on preoperative screening and optimal treatment of high lactate concentrations in this specific population is warranted. Clinicaltrials.gov identifier: NCT01524315.

Working memory and blood lactate levels.

The accumulation of lactate in the blood after a high-intensity exercise is associated with an increase of lactate extractions by the brain. Previously, a negative influence of blood lactate on attentional processes has been observed. The present study was carried out to examine the association of high blood lactate levels, induced with a maximal cycling, with another cognitive domain: working memory. For evaluation of working memory two different protocols were used: the first (Self-Ordered Pointing Task) capable of analyzing non-spatial working memory requiring the ability to generate and monitor a sequence of responses and the second for evaluating motor working memory necessary to perform a motor task. The study was carried out in 30 students (15 males and 15 females) who performed exhaustive exercise. In each subject, blood lactate was measured and motor as well as non-motor forms of working memory were evaluated before the exercise, at its end as well as 15min after the exhaustion. It was observed that an increase of blood lactate levels is associated with a worsening of both types of working memory.