Capillary Lactate Concentration Research Articles

Cardiac diastolic maladaptation is associated with the severity of exercise intolerance in sickle cell anemia patients

This pilot study focusing on Sickle Cell Anemia (SCA) patients offers a comprehensive and integrative evaluation of respiratory, cardiovascular, hemodynamic, and metabolic variables during exercise. Knowing that diastolic dysfunction is frequent in this population, we hypothesize that a lack of cardiac adaptation through exercise might lead to premature increase in blood lactate concentrations in SCA patients, a potential trigger for acute disease complication. SCA patients were prospectively included in PHYSIO-EXDRE study and underwent a comprehensive stress test with a standardized incremental exercise protocol up to 4 mmol L−1 blood lactate concentration (BL4). Gas exchange, capillary lactate concentration and echocardiography were performed at baseline, during stress test (at ∼ 2 mmol L−1) and BL4. The population was divided into two groups and compared according to the median value of percentage of theoretical peak oxygen uptake (%V˙O2peakth\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\\dot{\ ext{V}}\ ext{O}}_{2peakth}$$\\end{document}) at BL4. Twenty-nine patients were included (42 ± 12 years old, 48% of women). Most patients reached BL4 at low-intensity exercise [median value of predicted power output (W) was 37%], which corresponds to daily life activities. The median value of %V˙O2peakth\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\\dot{\ ext{V}}\ ext{O}}_{2peakth}$$\\end{document} at BL4 was 39%. Interestingly, diastolic maladaptation using echocardiography during stress test along with hemoglobin concentration were independently associated to early occurrence of BL4. As BL4 occurs for low-intensity exercises, SCA patients may be subject to acidosis-related complications even during their daily life activities. Beyond assessing physical capacities, our study underlines that diastolic maladaptation during exercise is associated with an early increase in blood lactate concentration.

Admission lactate concentration has predictive value for death or severe complications within 30 days after admission in cattle with long-bone fractures.

To determine the prognostic value of lactate concentration measurements at admission in cattle with long-bone fractures. 43 cattle with long-bone fractures between July 2016 and Dec 2018. In this prospective cohort study, lactate concentration was measured in systemic venous blood and locally in capillary blood sampled from the fractured and contralateral limbs of cattle and assessed for outcome prediction. The cutoff value was determined by maximizing the Youden index from receiver-operating characteristic curves. Multivariable logistic regression was employed to verify whether higher lactate concentrations compared with the cutoff value were an independent risk factor for poor outcomes at 30 days or 3 years after admission. Poor outcome was associated with higher capillary lactate concentration in the fractured limb (P < .001) and greater difference with systemic blood (P = .005). A cutoff value of lactate difference ≥ 2.4 mmol/L (sensitivity = 0.80; specificity = 0.965) between capillary lactate in the fractured limb and systemic blood was the best predictor of death ≤ 30 days after admission (P < .001). Multivariable analysis revealed that this cutoff value was an independent risk factor for 30-day and 3-year outcomes (P < .001). Admission blood lactate concentration difference ≥ 2.4 mmol/L between the fractured limb and systemic blood was a robust and independent predictor of outcome for cattle of the present report. Lactate metabolism is locally impaired in fractured limbs of nonsurviving or at higher complication risk cattle, which may help identify patients at high risk for poor outcomes.

Prehospital capillary lactate in children differentiates epileptic seizure from febrile seizure, syncope, and psychogenic nonepileptic seizure

PurposeThe aim of the study was to examine prehospital capillary lactate in children as a diagnostic biomarker to differentiate epileptic seizures from febrile seizures, syncope, and psychogenic nonepileptic seizures (PNES). MethodsCapillary lactate concentrations taken in a pediatric prehospital setting within 2 h of the paroxysmal event were compared retrospectively between patients with epileptic seizure, febrile seizure, syncope, and PNES, based on the final diagnosis from the hospitalization report. ResultsOne hundred and two patients were included, 53 (52%) with epileptic seizures, 41 (40%) with febrile seizures, and 8 (8%) with syncope or PNES. Capillary lactate in patients with a final diagnosis of epileptic seizure was significantly increased in comparison to the concentrations in patients with febrile seizure (p < 0.0007) and in comparison to the concentrations in patients with syncope or PNES (p < 0.0204). The area under the ROC-curve was 0.71 (95% CI 0.61–0.80). For a cutoff concentration of prehospital capillary lactate >3.9 mmol/l (Youden index), the sensitivity was 49% and the specificity 92%. ConclusionPrehospital capillary lactate concentrations are a useful tool for differentiating the nature of a paroxysmal event in children.

Comprehensive Evaluation and Determinant of Second Lactate Threshold in Homozygous Sickle Cell Disease

Following respiratory, cardiac and peripheral vascular impairments, Sickle Cell Disease (SCD) patients can experience early second lactate threshold (S2) during low intensity exercise. Through a comprehensive evaluation of exercise parameters we want to assess and find factors associated with an early reached of S2. Homozygous SCD patients were prospectively included in this study. They performed physical exercise with a standardized protocol. Gaz exchange, capillary lactate concentration measurements and echocardiography were performed at baseline and throughout the exercise until S2 was reached. Baseline and exercise data of the bottom and top half of patients in terms of %predicted VO2 at S2 were compared to investigate the determinant of an early S2, adjusted over age, sex and body mass index (BMI). Thirty patients were included (42 ± 12 years old, 50% of female). Bottom half group reached 34,5% ± 5,2 predicted VO2 at S2 (mean %predicted Watt = 32% ± 5,9) while top half group reached 46,2% ± 6,8 predicted VO2 at S2 (mean %predicted Watt = 42,8% ± 9,6) ( Fig. 1 ). Plasmatic hemoglobin concentration was the only baseline parameter associated with a lower %predicted VO2 at S2 (8.1 ± 1 vs. 9.2 ± 1 g/dl, P = 0.007). None of the baseline echocardiographic parameters were associated with a lower %predicted VO2 at S2. Diastolic adaptation through exercise was associated with a better power and VO2 at S2 (ratio S2/baseline of E’lateral wave and E/E’, respectively 1,39 vs. 1,63, P = 0,039 and 1,2 vs. 0,99, P = 0,004) SCD patients with lower hemoglobin and impaired diastolic adaptation through exercise displayed earlier S2, independently of age, sex and BMI. This highlights the great vulnerability of these patients to low metabolic stress. They should benefit from low intensity physical therapy programs.

Blood Lactate AUC Is a Sensitive Test for Evaluating the Effect of Exercise Training on Functional Work Capacity in Patients with Chronic Heart Failure.

Purpose Exercise training is an essential treatment option for patients with chronic heart failure (CHF). However, it remains controversial, which surrogate measures of functional work capacity are most reliable. The purpose of this paper was to compare functional capacity work measured as capillary lactate concentrations area under the curve (AUC) with standard cardiopulmonary exercise testing (CPET) with VO2peak and the 6-minute walk test (6 MWT). Methods Twenty-three patients in New York Heart Association (NYHA) class II/III with left ventricular ejection fraction (LVEF) <35% were randomised to home-based recommendation of regular exercise (RRE) (controls), moderate continuous training (MCT) or aerobic interval training (AIT). The MCT and AIT groups underwent 12 weeks of supervised exercise training. Exercise testing was performed as standard CPET treadmill test with analysis of VO2peak, the 6 MWT and a novel 30-minute submaximal treadmill test with capillary lactate AUC. Results All patients had statistically significant improvements in VO2peak, 6 MWT and lactate AUC after 12 weeks of exercise training: 6 MWT (p =0.035), VO2peak (p =0.049) and lactate AUC (p =0.002). Lactate AUC (p =0.046) and 6MWT (p =0.035), but not VO2peak revealed difference between the exercise modalities regarding functional work capacity. Conclusion 6-MWT and lactate AUC, but not VO2peak, were able to reveal a statistically significant improvement in functional capacity between different exercise modalities.

Feasibility and suitability of a graded exercise test in patients with aggressive hemato-oncological disease

PurposePhysical activity promises to reduce disease-related symptoms and therapy-related side effects in patients suffering from aggressive lymphoma (L) or acute leukemia (AL). For an efficient training program, determination of patients’ physical capacity with a purposive exercise test is crucial. Here, we evaluated the feasibility and suitability of a graded exercise test (GXT) frequently applied in patients suffering from solid tumors by assessing whether patients achieved criteria for maximal exercise testing according to the American College of Sports Medicine (ACSM).MethodsThe GXT was performed by 51 patients with an aggressive L or AL prior to the start or in the earliest possible phase of high-dose chemotherapy, following a recommended protocol for cancer patients, starting at 20 Watts (W), with an increase of 10 W/min until volitional exhaustion. Subsequently, we investigated whether the following ACSM criteria were fulfilled: (1) failure of heart rate to increase despite increasing workload, (2) post-exercise capillary lactate concentration ≥ 8.0 mmol L−1, (3) rating of perceived exertion at exercise cessation > 17 on the 6–20 Borg Scale.ResultsOut of 51 patients, two, six, and 35 participants met the first, second, and third criterion, respectively. No relevant relationships between the completion of the criteria and patients’ characteristics (e.g., gender, age) were found.ConclusionAlthough results of this study suggest a general feasibility of the applied GXT, the ACSM criteria were not met by the majority of the participants. Therefore, this study raises doubts about the suitability of the GXT protocol and the ACSM criteria for this group of patients.

A new aerobic fitness score based on lactate sensing during submaximal exercise.

Given the known clinical utility of cardiorespiratory fitness, measurement of physiological responses to submaximal exercise may be a feasible approach well suited for diagnostic and prognostic purposes in non-athletes and the chronically ill. Lactate levels and watt output during a short submaximal exercise and a subsequent relaxation period yield an aerobic score that is consistent with cardiorespiratory fitness grades in non-athletes and that may be used as a marker in such approaches. In this study, 28 females (23 ± 3 years) were submitted to a 15 min submaximal recumbent bike session, and their capillary and saliva lactate concentrations were recorded and plotted against time. An individual aerobic score was calculated from this curve, using watt output during equal relative percentiles of maximum heart-rate benchmarks. The scores were compared with respective results in a V̇O2max test and with a similar scoring system in 14 older (51 ± 9 years) females; they correlated with the 6 categories of the V̇O2max test results and classified into 3 categories of V̇O2max grades (very poor/poor; fair/good; excellent/superior) with a combined accuracy of 80.95%. More studies are required to validate the potential utility of this submaximal test as an additional risk factor for diagnostic purposes in non-athletes. Novelty points: A novel method for estimating cardiorespiratory fitness during submaximal exercise consistent with V̇O2max performance. The method yields an aerobic score that may be used as a marker for diagnostic and prognostic purposes.

PL - 036 Interactive effects of exercise and metformin on lactic metabolism in type 2 diabetes

Objective Lactic acidosis is typically caused by an imbalance in lactic metabolism. This may be attributed to several reasons and is usually a result of complex interactions. There may be an increased risk for lactic acidosis in type 2 diabetes mellitus (T2D) patients when metformin treatment and physical exercise are combined since both metformin and exercise acutely affect lactic metabolism. As timing of exercise following metformin ingestion may determine the magnitude of long-term metabolic adaptations, this study aimed to test the acute effects of exercise performed at different times following metformin ingestion on lactic metabolism in T2D patients with a randomized crossover time series study design.&#x0D; Methods Participants were recruited from two clinical health-care centers in China using a two-step screening procedure. First, approximately 2 523 patients with T2D were screened from the local diabetes database and clinical outpatient registration with inclusion criteria being men and women (30–65 years old) diagnosed with T2D no more than 5 years ago and treated with metformin (maximal daily dose of 2000 mg). Out of 100 potential participants who met the inclusion criteria, 56 were interested and invited to a laboratory visit. Finally, 34 patients participated in the study and of those, 26 patients (14 women and 12 men, mean age = 53.8 ± 8.6 years) completed all testing procedures.&#x0D; All patients visited the laboratory on 4 occasions, each separated by at least 48 hours. Initially a control visit was performed and consisted of metformin administration only (Metf) and a maximal incremental cycle ergometer test in the afternoon. Thereafter, all participants performed a high-intensity interval training session (HIIT, 3 minutes at 40% followed by 1 minute of 85% of maximum power output) 30 minutes (EX30), 60 minutes (EX60), and 90 minutes (EX90) post breakfast and metformin administration, respectively, in a randomized order.&#x0D; Serum lactate and glucose concentrations were assessed enzymatically, while insulin was assessed by an electrochemiluminescence immunoassay and superoxide dismutase (SOD) activity was determined by spectrophotometry. Measurements were performed before breakfast as well as both before and immediately after each exercise bout. In addition, capillary blood glucose concentrations were measured immediately after sampling using Omron AS1 glucose test strips (HGM-114) and lactate concentrations were assessed by ARKRAY Lactate Pro 2 test strips throughout each measurement day. Dietary intake was standardized on the evening prior to each laboratory day as well as between 8:00 a.m. and 4:00 p.m. during each testing day. This trial is registered with ChiCTR-IOR-16008469 on 13th of May 2016.&#x0D; Results During all three-exercise sessions, the capillary lactate concentrations were significantly increased to a similar extent. However, sixty minutes following metformin administration, serum lactate levels began to accumulate to the highest level, where 30% of patients showed lactate concentrations above resting values (≥2 mmol·L-1). The increased lactate concentrations were statistically associated with increased glucose when exercise was performed 60 minutes post metformin administration (r=0.384, p=0.048). Furthermore, in EX60 and EX90 lactate concentrations were 19% and 8% higher, respectively, compared to EX30. In addition, we found that after exercise but not before exercise, the lactate level was positively correlated with SOD (EX30 r=0.478 and p=0.012, EX60 r=0.562 and p=0.002, EX90 r=0.562 and p=0.003, respectively).&#x0D; Conclusions We found that the changes of lactate concentrations were related to the timing of exercise post meal and after metformin ingestion. Thus, timing of exercise appears to be an important factor to be considered when prescribing exercise for T2D patients treated with metformin. In the present study, the optimal timing of HIIT exercise was 30 minutes after metformin administration, which was indicated by a minimized fluctuation of both glucose and lactate levels in T2D patients. Our results also suggest that lactic metabolism and oxidative stress could be among the main underlying molecular mechanisms that elucidate the combinational therapy of exercise and metformin treatment on T2D. Since both acute exercise and metformin may induce opposite effects on ATP production and reactive oxygen species formation, it is important to conduct further studies in an attempt to define the “safe time” for exercise after metformin administration.

Global Dynamics of a Piecewise Smooth System for Brain Lactate Metabolism

In this article, we study a piecewise smooth dynamical system inspired by a previous reduced system modeling compartimentalized brain metabolism. The piecewise system allows the introduction of an autoregulation induced by a feedback of the extracellular or capillary Lactate concentrations on the Capillary Blood Flow. New dynamical phenomena are uncovered and we discuss existence and nature of two equilibrium points, attractive segment, boundary equilibrium and periodic orbits depending of the Capillary Blood Flow.

Effect of Two Different Types of Olympic Rotation Order on Cardiovascular and Metabolic Variables in Men's Artistic Gymnastics.

The rotation sequence-order differs from a gymnast to another according to the draw at the time of the qualifying competitions in men’s artistic gymnastics. Only the six best gymnasts start on the floor exercises, the others could start on any of the other five apparatuses. It has been demonstrated that some gymnastics events are physiologically less taxing than others; hence some gymnasts could experience lower and/or higher levels of cardiovascular and metabolic stress compared to others, depending on the apparatus they start with. In this regard, the objective of this investigation was to compare cardiovascular and metabolic variables between two different types of Olympic rotation-order; one began with the floor exercises and the other began with the pommel horse. Six elite male gymnasts took part in this investigation. Heart rates, synchronized with real-time video acquisition, as well as capillary lactate concentration following each apparatus routine were monitored. Cardiovascular and metabolic stresses were significantly higher when gymnasts started their rotation with the pommel horse in all apparatuses except the pommel horse. The floor exercises’ score was significantly affected when gymnasts ended up their competition on this apparatus. As a conclusion, starting gymnastics’ competition on the floor exercises implicates less cardiovascular and metabolic stress associated with better performance compared with the other rotation order. As a matter of fact, best gymnasts who start on this apparatus could have a slight advantage compared with the other athletes.

Capillary and venous point-of-care testing of lactate concentrations in the emergency department: a prospective observational study

BackgroundHyperlactatemia is a sensitive marker for early identification of patients who are critically ill. Rapid capillary lactate measurement using a handheld device can hasten the identification of patients at risk. We aimed to compare capillary lactate with venous blood lactate assessed using a blood gas analyser in the emergency department. MethodsThis was a prospective observational study of patients presenting to the emergency department in Hong Kong SAR. Venous and fingertip capillary blood samples were collected for lactate analysis. Venous lactate concentrations measured using a point-of-care blood gas analyser was used as a reference method (VL-Ref). Capillary lactate concentrations were measured using two handheld analysers: (1) Nova StatStrip Xpress (CL-Nova); and (2) Lactate Scout+ (CL-Scout+). Venous lactate measurements were also done using two handheld analysers (VL-Nova and VL-Scout+). Bland-Altman analysis was used to determine the agreement between different methods of measurement. Ethics approval was obtained from the Institutional Review Board of the Chinese University of Hong Kong (CREC 2015.624). Written consent was obtained either from the patient or a relative in all cases. The study is registered with ClinicalTrials.gov (NCT02694887). FindingsBetween March and July, 2016, we recruited 240 patients (aged 18 years or older) who were triage category 3 (urgent) presenting to the emergency department. Of 240 patients (mean age 69·9 years; 54% men), lactate concentrations were in the range 0·70–5·38 mmol/L (mean 1·96mmol/L). 151 patients (63%) had lactate concentrations (VL-Ref) less than 2 mmol/L, and 89 patients (37%) had lactate concentrations of at least 2 mmol/L. The results of a Bland-Altman analysis showed that percentage of mean difference were −6·2% between VL-Ref and CL-Scout+, 29·9% between VL-Ref and CL-Nova, with 95% limits of agreement of −79·3 to 66·8% and −43·8 to 103·6%, respectively. Regarding venous blood lactate, the results showed bias values of 13% between VL-Ref and VL-Scout+, 55·3% between VL-Ref and VL-Nova, with limits of agreement being −23·9 to 49·9% and 20·7 to 90·0%, respectively. InterpretationAn overall low systemic bias were observed in CL-Scout+ (bias −6·2%) and VL-Scout+ (bias 13%), suggesting the potential clinical utility of the Scout+ handheld analyser. However, the wide range of limits of agreement implies poor precision of using fingertip capillary blood for lactate testing. Further studies are needed to validate the use of capillary lactate in emergency settings. FundingDirect Grant for Research, The Chinese University of Hong Kong.

Capillary lactate concentration on admission of normotensive trauma patients: a prospective study.

BackgroundElevated serum blood lactate is an indicator of on-going bleeding in severe trauma patients. Point-of-care (POC) capillary lactate measurement devices may be useful to rapidly assess lactate concentration at the bedside. The aim of this study was to test the diagnostic performance of capillary lactate to predict significant transfusion in normotensive trauma patients.MethodsWe conducted a prospective observational study in one level-I trauma centre. From August 2011 to February 2013, 120 consecutive adult patients with systolic blood pressure (SBP) higher than 90 mmHg were included. Capillary lactate was measured on admission in the trauma bay. The primary outcome was defined as a significant transfusion within the first 48 h. Diagnostic performance was determined using receiver operating characteristic (ROC) curve analysis. We also tested the agreement between capillary lactate and blood lactate concentrations using Bland and Altman analysis.ResultsOf the 120 normotensive trauma patients, 30 (25 %) required at least one unit of packed red blood cells (RBC) and 12 (10 %) patients received at least four RBC within the first 48 h. All patients with significant RBC transfusion had capillary lactate higher than 3.5 mmol/l. The area under the ROC curve of capillary lactate on admission to predict transfusion of at least 4 RBC units was 0.68 [95 % CI 0.58 – 0.78]. The average bias between capillary and blood lactate measurements was 2.4 mmol/l with a standard deviation of 3.0 mmol/l (n = 60 patients).ConclusionsAlthough a significant association was found between POC lactate concentration and transfusion requirements, the diagnostic performance of capillary lactate measurements was poor. Due to large disagreement between capillary lactate and blood lactate, capillary lactate cannot be considered in the clinical setting.Trial registrationClinicalTrials.gov, No. NCT01793428.Electronic supplementary materialThe online version of this article (doi:10.1186/s13049-016-0272-x) contains supplementary material, which is available to authorized users.

Capillary lactate as a tool for the triage nurse among patients with SIRS at emergency department presentation: a preliminary report

BackgroundThe triage nurse is involved in the early identification of the most severe patients at emergency department (ED) presentation. However, clinical criteria alone may be insufficient to identify them correctly. Measurement of capillary lactate concentration at ED presentation may help to discriminate these patients. The primary objective of this study was to identify the prognostic value of capillary lactate concentration measured by the triage nurse among patients presenting to the ED.MethodsThis was a prospective observational study, performed in the ED of a university hospital. At ED presentation, capillary lactate measurement was performed by the triage nurse among patients presenting with a clinical criteria of systemic inflammatory response syndrome (SIRS). Clinical variables usually used to determine severity were collected at presentation. Twenty-eight-day mortality and MEDS score were recorded.ResultsOne hundred seventy-six patients with clinical SIRS presented to the ED. Median age was 72 years, and 28-day mortality was 16%. Capillary lactate at ED presentation was significantly higher among 28-day non-survivors than among survivors (5.7 mmol.L−1 [3.2 to 7.4] vs 2.9 mmol.L−1 [1.9 to 5.2], p = 0.003). A score based on mottling and capillary lactate concentration >3.6 mmol.L−1 was significantly associated with 28-day mortality (area under curve, AUC = 0.75), independently of the MEDS score (AUC = 0.79) for the prediction of 28-day mortality (AUC global model 0.87).ConclusionsA high capillary lactate concentration measured by the triage nurse among patients presenting to the ED with clinical SIRS is associated with a high risk of death. A score calculated by the triage nurse, based on mottling and capillary lactate concentration, appears to be useful for identifying the most severe patients.

A Pilot Study on the Physiological Response to an Official Breed Evaluation Field Test in Icelandic Horses

IntroductionThe aim of this study was to describe the response in heart rate, respiratory rate, rectal temperature, hematocrit and plasma lactate concentration in Icelandic horses performing the riding assessment in an official breed evaluation field test (BEFT) in Iceland (April 2011). It was hypothesized that the riding assessment constituted high intensity exercise.MethodsData was collected from 15 of 28 horses shown at the BEFT. Horses were judged for riding abilities (all gaits) on a straight track. Respiratory rate and rectal temperature were recorded and blood samples were taken from the jugular vein before the warm‐up and within 5 min after the riding assessment. Hematocrit was analysed by centrifugation of capillary tubes and plasma lactate concentration using an enzymatic and spectrophotometric method. Velocity, distance and heart rate were recorded (Polar, Kempele, Finland) during the riding assessment. Anova (Proc GLM) was performed in SAS and data is presented as LSMean ± SE (P&lt;0.05).ResultsThe distance covered was 2.7 ± 0.1 km, the duration 9:13 ± 0:21 min : sec and the average speed 17.5 ± 0.3 km/h. The peak heart rate was 214 ± 3 bpm. Post‐exercise plasma lactate concentration was 18.6 ± 1.7 mmol/L and there was an increase (P&lt;0.001) in respiratory rate (40 ± 6 to 118 ± 6 breaths/min), rectal temperature (38.1 ± 0.1 to 39.8 ± 0.1°C) and hematocrit (35 ± 2 to 47 ± 2%) following the breed evaluation field test.ConclusionsThe physiological responses indicate that the riding assessment in BEFT is a demanding exercise, requiring some contribution of anaerobic metabolism.Ethical Animal ResearchThe study was approved by the National Animal Research Committee of Iceland. Owners and trainers were informed that participation was voluntary. Sources of funding: Developmental Fund of the Icelandic Horse Breeding, the Pálmi Jónsson Natural Conservation Fund and the Stock Protection Fund of the Icelandic Horse breed. Competing interests: none.

Single Rescuer Exertion Using a Mechanical Resuscitation Device: A Randomized Controlled Simulation Study

The goal of this experimental study was to investigate rescuer exertion when using "Animax," a manually operated hand-powered mechanical resuscitation device (MRD) for cardiopulmonary resuscitation (CPR), compared to standard basic life support (BLS). This was a prospective, open, randomized, crossover simulation study. After being trained, 80 medical students with substantial knowledge in BLS performed one-rescuer CPR using either the MRD or the standard BLS for 12-minute intervals in random order. The main outcome parameter was the heart rate pressure product (RPP) as an index of cardiac work. Secondary outcome parameters were physical exhaustion quantified by the Borg scale (measurement of perceived exertion), Nine Hole Peg Test (NHPT; measurement of fine motor skills), and capillary lactate concentration during testing. While no significant difference could be found for the RPP, a significantly increased mean heart rate during the final minute of standard BLS compared to the MRD was found (139 ± 22 beats/min vs. 135 ± 26 beats/min, p = 0.027). By contrast, subjective exertion using the MRD was rated significantly higher on the Borg scale (15.1 ± 2.4 vs. 14.6 ± 2.6, p = 0.027). Mean serum lactate concentration was significantly higher when the MRD was used compared to standard BLS (3.4 ± 1.5 mmol/L vs. 2.1 ± 1.3 mmol/L, p ≤ 0.001). Use of the MRD leads to a RPP of the rescuers comparable to standard BLS. These findings suggest that there is no clinically relevant reduction of exertion if this MRD is used by a single rescuer. If this kind of MRD is used for CPR, frequent changeovers with a second rescuer should be considered as the guidelines suggest for standard CPR.

Enhanced Myofiber Recruitment During Exhaustive Squatting Performed as Whole-Body Vibration Exercise

The purpose of the study was to test the hypothesis that myofiber recruitment is enhanced when whole-body vibration (WBV) is added to squat training. In a randomized cross-over design, 14 recreationally active men were subjected to 2 sessions consisting of 5 sets of 10 squats with external load, performed either on a vibration platform (whole-body vibration squatting [WBVS]) or conventionally without WBV (CON). Electromyographic (EMG) activity of the right vastus lateralis muscle was continuously recorded during WBVS and CON. The integrated EMG values were normalized to the EMG activity recorded during measurement of the maximal voluntary contraction force (MVC) on an isometric leg press at the beginning of each training session. Capillary lactate concentration was determined before and repeatedly after the squatting exercise. Overall mean normalized and integrated EMG (nIEMG) activity during WBVS (62 ± 4% MVC) was significantly (p < 0.001) higher compared with CON (47 ± 2% MVC). There was a tendency for nIEMG to increase during the 5 sets of 10 squats performed as WBVS (p = 0.089), whereas there was a significant (p < 0.001) decrease in nIEMG during CON. Whole-body vibration squatting induced a significantly (p < 0.001) larger increase in capillary lactate than CON (3.03 ± 0.32 vs. 1.60 ± 0.30 mmol · L(-1), p < 0.001). The increased myoelectric activity and the enhanced exercise-induced increase in capillary lactate concentration during WBVS provide evidence for augmented recruitment of muscle tissue when WBV is added to exhaustive squatting exercise.

Performance and physiological responses to repeated-sprint exercise: a novel multiple-set approach

We investigated the acute and chronic responses to multiple sets of repeated-sprint exercise (RSE), focusing on changes in acceleration, intermittent running capacity and physiological responses. Ten healthy young adults (7 males, 3 females) performed an incremental test, a Yo-Yo intermittent recovery test level1 (Yo-Yo IR1), and one session of RSE. RSE comprised three sets of 5 × 4-s maximal sprints on a non-motorised treadmill, with 20 s of passive recovery between repetitions and 4.5 min of passive recovery between sets. After ten repeated-sprint training sessions, participants repeated all tests. During RSE, performance was determined by measuring acceleration, mean and peak power/velocity. Recovery heart rate (HR), HR variability, and finger-tip capillary lactate concentration ([Lac(-)]) were measured. Performance progressively decreased across the three sets of RSE, with the indices of repeated-sprint ability being impaired to a different extent before and after training. Training induced a significant increase (p < 0.05) in all indices of performance, particularly acceleration (21.9, 14.7 and 15.2% during sets 1, 2 and 3, respectively). Training significantly increased Yo-Yo IR1 performance by 8% and decreased Δ[Lac(-)]/work ratio (-15.2, -15.5, -9.4% during sets 1, 2 and 3, respectively) and recovery HR during RSE. There were strong correlations between Yo-Yo IR1 performance and indices of RSE performance, especially acceleration post-training (r = 0.88, p = 0.004). Repeated-sprint training, comprising only 10 min of exercise overall, effectively improved performance during multiple-set RSE. This exercise model better reflects team-sport activities than single-set RSE. The rapid training-induced improvement in acceleration, quantified here for the first time, has wide applications for professional and recreational sport activities.

Correlação dos graus de obstrução na DPOC com lactato e teste de caminhada de seis minutos

Chronic obstructive pulmonary disease (COPD) is a leading cause of morbid-mortality world wide, leading not only to pulmonary damage but also to multi-systemic impairment, with repercussions on skeletal muscles and the ability to undertake effort, as measured in the six-minute walk test (6-MWT).Aims: To correlate the level of obstruction in COPD with lactate concentration and heart rate (HR) at rest, and distance walked. To correlate distance walked with blood gas analysis and correlate desaturation in 6-MWT with post 6-MWT lactate concentration and heart rate.Methods: COPD patients underwent spirometry, blood gas analysis and 6-MWT to evaluate distance walked, heart rate, capillary lactate (CL) concentration pre– and post 6MWT, and desaturation with 6-MWT.Results: 91 patients with all levels of obstruction were evaluated. HR and CL increased significantly post 6-MWT. The decrease in peripheral saturation of haemoglobin to oxygen observed with 6-MWT was also significant. The distance walked was shorter the greater the obstruction. The correlation analysis was significantly positive between FEV1 and distance walked, negative between FEV1 and HR at rest and negative between distance walked and PaCO2, and not significant for the other variables.Conclusions: Increased obstruction in COPD and higher PaCO2 values contribute to a reduction in distance walked in 6-MWT. The level of obstruction in COPD leads to a haemodynamic impairment with increased HR at rest of these patients.Rev Port Pneumol 2009; XV (1): 11-25

Correlation of levels of obstruction in COPD with lactate and six-minute walk test

Chronic obstructive pulmonary disease (COPD) is a leading cause of morbid-mortality world wide, leading not only to pulmonary damage but also to multisystemic impairment, with repercussions on skeletal muscles and the ability to undertake effort, as measured in the six-minute walk test (6-MWT). AimsTo correlate the level of obstruction in COPD with lactate concentration and heart rate (HR) at rest, and distance walked. To correlate distance walked with blood gas analysis and correlate desaturation in 6-MWT with post 6-MWT lactate concentration and heart rate. MethodsCOPD patients underwent spirometry, blood gas analysis and 6-MWT to evaluate distance walked, heart rate, capillary lactate (CL) concentration pre– and post 6MWT, and desaturation with 6-MWT. Results91 patients with all levels of obstruction were evaluated. HR and CL increased significantly post 6-MWT. The decrease in peripheral saturation of haemoglobin to oxygen observed with 6-MWT was also significant. The distance walked was shorter the greater the obstruction. The correlation analysis was significantly positive between FEV1 and distance walked, negative between FEV1 and HR at rest and negative between distance walked and PaCO2, and not significant for the other variables. ConclusionsIncreased obstruction in COPD and higher PaCO2 values contribute to a reduction in distance walked in 6-MWT. The level of obstruction in COPD leads to a haemodynamic impairment with increased HR at rest of these patients.

Risk of exercise-induced hypoglycaemia in patients with type 2 diabetes on intensive insulin therapy: Comparison of insulin glargine with NPH insulin as basal insulin supplement

Aim Hypoglycaemia is the most common adverse event associated with intensive conventional insulin therapy (ICT). This study compared the risk of exercise-related hypoglycaemia in type 2 diabetes patients receiving either basal insulin glargine or NPH insulin. Methods In a prospective trial, 122 ICT patients (glargine n = 60, NPH n = 62) had a standardized treadmill test, monitored by capillary lactate concentration. Blood glucose (BG) profiles were performed the day before, during and the day after the exercise test, with the patients on a strict carbohydrate-defined diet. All patients had been on a stable ICT scheme for at least three months and had an HbA1c below 7.5%. Results BG at the beginning of the exercise test, BG decline and lowest BG during the test were comparable between the two groups. The episodes of mild hypoglycaemia (BG < 3.3 mmol/l) and amounts of additional carbohydrate intake due to mild symptoms of hypoglycaemia (BG 3.3–5.0 mmol/l) were not significantly different. No episodes of hypoglycaemia occurred during several hours after the exercise. Conclusions Moderate physical activity can be recommended for well-controlled type 2 diabetes patients receiving ICT, independently of glargine or NPH as basal insulin and without risk of exercise-induced hypoglycaemia.