Comparison of blood lactate concentrations in central venous, pulmonary artery, and arterial blood

Arterial blood lactate is regarded as a very good indicator of the severity and prognosis of circulatory shock. Accordingly, the practical issue of whether such measurements might be equally valid on blood sampled from the right atrium or superior vena cava or from the pulmonary artery was investigated. In blood sampled prospectively on 50 occasions in 12 patients (group 1), arterial blood lactate ranged from 0.39 to 9.71 mmol/L. A very high correlation (r = .995) was observed between blood sampled simultaneously from an arterial and central venous catheter. The maximum absolute difference was 0.5, and mean difference 0.029 mmol/L. Comparable correlations were obtained between arterial and simultaneously sampled pulmonary artery blood (r = .994). We analyzed retrospectively the results of lactate analyses on 104 paired blood samples from the pulmonary artery and peripheral artery in 23 critically ill and injured patients (group 2) whose arterial blood lactates ranged from 0.46 to 12.99 mmol/L. We also found a high correlation (r = .998) between arterial and simultaneously sampled pulmonary artery blood lactate. The maximum absolute difference was 0.82, and the mean difference 0.03 mmol/L. These data demonstrate that lactate measurements in venous blood sampled either from a pulmonary artery or from a central venous catheter yield lactate concentrations essentially equivalent to those in arterial blood.     

Prognostic value of blood lactate in critically ill patients

Hyperlactatemia is frequently observed in critically ill patients. A correlation of blood lactate concentrations and outcome of patients has been proven in circulatory shock, circulatory arrest, acute myocardial infarction, acute hypnotic drug poisoning and severe pancreatitis. However, the prognostic relevance of hyperlactatemia yields from statistical examinations in larger groups of patients. It should not be misused as a reliable prognostic sign in the individual patient, but is of high value in comparing groups of patients. In individual patients, hyperlactatemia is a useful indicator pointing to the severity of illness and to superimposed complications. Blood lactate is of considerable value for the metabolic monitoring of critically ill patients.     

Plasma ionized calcium and blood lactate concentrations are inversely associated in human lactic acidosis

Plasma ionized calcium [Ca⁺⁺] concentrations are decreased in patients having lactic acidosis. To further investigate this observation, we prospectively studied nine critically ill patients who had lactic acidosis and measured arterial pH, PCO₂, [Ca⁺⁺], lactate, and albumin concentrations. We found a strong association between decreased [Ca⁺⁺] and increased plasma lactate concentrations (r ²=0.78,p0.001). This unexpected association — [Ca⁺⁺] usually increases with increasing acidosis — might be clinically important and the mechanism deserves further investigation. Sources of support: BC Heart Foundation; BC Health Care Research Foundation; Canadian Heart Foundation     

Running velocities and heart rates at fixed blood lactate concentrations in young soccer players

The purpose of this study was to examine the running velocities and heart rates at fixed lactate concentrations of young soccer players according to playing position and age. A total of 223 young male soccer players participated in this study. Each player performed incremental exercise tests on a treadmill. Running velocities and heart rates at 2 mmol/L⁻¹, 2.5 mmol/L⁻¹, 3 mmol/L⁻¹, and 4 mmol/L⁻¹ blood lactate concentrations were calculated with use of the spline function. Data were analyzed through analysis of variance to examine differences among various playing positions (ie, defenders, midfielders, and forwards) and 3 age groups (U17, under 17 y; U19, under 19 y; and U21, under21 y). No significant differences were discerned between defenders, midfielders, and forwards in terms of running velocities and heart rates in accordance with specified lactate concentrations. Running velocities corresponding to all lactate concentrations showed no significant differences at all age groups, but heart rates in soccer players in the U21 and U19 age groups were significantly lower than in the U17 age group. Following a 3-y trial of 20 players, running velocities increased and heart rates decreased at all corresponding lactate concentrations. Results of this study suggest that (1) the endurance performance level of young soccer players is similar for all positions, and (2) heart rates are lowered with age and with training.     

Running velocities and heart rates at fixed blood lactate concentrations in elite soccer players

This study was undertaken to examine the endurance performance of elite soccer players, according to age and playing position. A total of 197 male soccer players participated in this study. Each player performed exercise tests on the treadmill that included 3-minute runs and 30-second blood sampling intervals. During these tests, running speeds at the first and second stages were 10 km/hr^-1 and 12 km/hr^-1, respectively. When these tests were completed, running speed was increased by 1 km/hr every 3 minutes until the runner reached exhaustion. Blood samples were analyzed immediately by means of an automated lactate analyzer. Heart rate was monitored continuously at 5-second intervals. Running velocities and heart rates at 2-mmol/L^-1, 2.5-mmol/L^-1, 3-mmol/L^-1, and 4-mmol/L^-1 blood lactate concentrations were calculated with use of the spline function. Analysis of variance was used to analyze data to determine the differences between playing positions (goalkeepers, defenders, midfielders, and forwards) and age groups (older than 30 years of age, between 25 and 29 years old, between 20 and 24 years old, and 19 years old and younger). Statistical significance was set at P > .01. No significant differences were revealed between defenders, midfielders, and forwards regarding running velocities and heart rates and their correlation with specified lactate concentrations. Goalkeepers demonstrated lower endurance performance than players in the other playing positions (P > .001). Running velocities corresponding to all lactate concentrations showed no significant differences in all age groups, but heart rates in soccer players older than 30 years of age were significantly lower than those of players in other age groups (P > .01). Results of this study suggest that the endurance performance level of professional players is similar for players in all positions, except for goalkeepers, and that endurance performance is not adversely affected when a person\rss age increases beyond 30 years of age.     

Interpreting cobalt blood concentrations in hip implant patients

Introduction. There has been some recent concern regarding possible systemic health effects resulting from elevated blood cobalt concentrations in patients with cobalt containing hip implants. To date there are no blood cobalt criteria to help guide physicians when evaluating an individual hip implant patient's risk of developing systemic health effects because historically there was little or no concern about systemic cobalt toxicity in implant patients. Objective. Our purpose is to describe recently completed research regarding the relationship between blood cobalt concentrations and clinical health effects. We discuss the possibility of systemic health effects in patients with metal containing implants and propose various blood cobalt concentrations that are not associated with an increased risk of developing certain adverse effects. Methodology. The primary literature search was conducted using PubMed and Web of Science using the following search terms: cobalt AND (toxicity OR health effects OR cardiotoxicity OR hematological OR endocrine OR immunological OR reproductive OR testicular effects OR neurological OR case report OR cohort OR Roncovite). The searches identified 6786 papers of which 122 were considered relevant. The Agency for Toxic Substances and Disease Registry toxicological profile for cobalt and the U.S. Environmental Protection Agency Office of Research and Development's National Center for Environmental Assessment's documentation on the provisional peer-reviewed toxicity value for cobalt were also utilized to identify secondary literature sources. Results. Our review of the toxicology and medical literature indicates that highly elevated blood cobalt concentrations can result in certain endocrine, hematological, cardiovascular, and neurological effects in animals and/or humans. These studies, in addition to historical clinical findings involving the therapeutic use of cobalt, indicate that significant systemic effects of cobalt will not occur below blood cobalt concentrations of 300 μg/L in most persons. Some individuals with specific risk factors for increased susceptibility (e.g., severe and sustained hypoalbuminemia) may exhibit systemic effects at lower cobalt blood concentrations. This review also describes several cobalt dosing studies performed with human volunteers that consumed cobalt for 15, 30, or 90 days. Overall, the results of these dosing studies indicate that sustained blood cobalt concentrations averaging 10–70 μg/L for up to 90 days cause no significant clinical effects (maximum concentrations approached 120 μg/L). Some proposed blood criteria for assessing implant wear and local tissue damage have been suggested by several medical groups. For example, the UK Medicines and Healthcare Products Regulatory Agency has proposed a blood cobalt guidance value of 7 μg/L, and the Mayo Clinic has suggested serum cobalt concentrations greater than 10 μg/L, but both of these values are primarily intended to address implant wear and to alert physicians to the possibility of an increased incidence of local effects. There is a clear lack of consensus regarding how to identify a specific numerical blood concentration of concern and whether whole blood or serum is a better matrix to assess total cobalt concentration. Conclusions. Based on currently available data, only under very unusual circumstances should a clinician expect that biologically important systemic adverse effects might occur in implant patients with blood cobalt concentrations less than 300 μg/L. Patients with metal-containing hip implants who exhibit signs or symptoms potentially related to polycythemia, hypothyroidism, neurological, or cardiac dysfunction should be clinically evaluated for these conditions. Polycythemia appears to be the most sensitive endpoint.     

Elevated hyaluronan blood concentrations in severely burned patients.

Hyaluronan (HYA) is a polysaccharide found in the interstitial matrix in most tissues. HYA is removed by lymphatic drainage and degraded in local lymph nodes and in the liver. Its normal concentration in human plasma is very low (10-100 micrograms l-1). Following major burn injury in sheep plasma HYA can increase to levels tenfold greater than normal. In the present study, serum HYA concentrations were determined in 10 severely burned patients (burn size: 28 +/- 5% of body surface area (mean +/- SEM)). Serum HYA concentration was 206 +/- 71 micrograms l-1 at 24 h post-injury, twice the upper normal HYA concentration, and remained moderately elevated for the first week post-injury. It appears that mobilization and transport of HYA from the tissues is increased after thermal injury. Increased systemic concentrations of an interstitial matrix component have not previously been reported in burn patients. Possibly, plasma concentrations of connective tissue components might serve as indicators of the severity and extent of burn injuries.     

Associations of blood homocysteine concentrations in Arab schizophrenic patients

BACKGROUND: This study aimed to evaluate the blood homocysteine concentration in Arab patients with schizophrenia and assess its associations with clinical phenotypes of the disease. SUBJECTS AND METHODS: Two age-matched groups of subjects were studied: (1) Healthy Controls, HC, n=165; (2) patients with schizophrenia, SZ: n=207. Each subject was evaluated with a standard questionnaire for age at disease onset, family history, disease severity and outcome. Plasma homocysteine levels (Hcys) were measured by immunoassay and serum levels of other biochemical parameters were measured by routine Autoanalyzer techniques. RESULTS AND DISCUSSION: Group HC was heavier (body mass index, BMI) while SZ had greater waist-hip ratio (WHR) and plasma Hcys levels. In SZ, there were significant correlations between Hcys and BMI, triglycerides and HDL. Hcys levels in SZ were highest in the younger male patients. CONCLUSION: Schizophrenic patients have increased blood Hcys levels which correlate with components of the metabolic syndrome. Hcys levels were highest in the younger male patients and were not influenced by prognostic features of the disease.     

Concentrations of superoxide dismutase and superoxide anion in blood of patients with respiratory infections and compromised immune systems

To investigate the involvement of oxygen free radicals and their scavenger systems in the defenses of compromised hosts against pulmonary infections, we determined superoxide anion (SOA) and superoxide dismutase (SOD; EC 1.15.1.1) concentrations in the blood of compromised hosts and noncompromised hosts, with or without pneumonia. In the compromised hosts without pneumonia (compromised controls), SOD concentrations were lower than in noncompromised hosts (healthy controls). However SOA values in compromised controls did not differ statistically from that in healthy controls. Similar changes were observed in noncompromised hosts with pneumonia. In compromised hosts with pneumonia, SOD concentrations were further decreased by pulmonary infections. By contrast, SOA values were increased in pneumonia. There were, however, no differences in the values for ceruloplasmin among all the groups. The values for alpha 2-macroglobulin and alpha1-antitrypsin were within normal limits in compromised controls but were greater in compromised hosts with pneumonia. These results suggest that a decreased activity concentration of SOD in compromised controls may be partly responsible for the depression of the host's immune defenses.     

Correlation between acid-base status, concentrations of lactate and of pyruvate in blood and cerebrospinal fluid in patients treated in an intensive care unit.

Results of examinations of 41 patients treated in an intensive care unit are reported. The patients were divided into three groups and examined on the first and twelfth days of treatment. In the first group were 15 patients who had received circulatory resuscitation, the second group was 13 patients with lesions of the central nervous system of traumatic or vascular origin and the third group was 13 patients with acute respiratory insufficiency of toxic or infective origin. The cerebrospinal fluid of patients in the second group showed the lowest pH (mean pH 7.28) and bicarbonate concentration (19.05 mequiv./1); this group also had the lowest PO2 values. Moderate respiratory alkalosis was observed in the arterial blood of patients with lesions of the central nervous system. Concentrations of lactate in the cerebrospinal fluid were increased in all three groups of patients although blood lactate concentrations were normal. The lactate/pyruvate concentration ratio was highest in the resuscitated patients.     

Influence of mechanical ventilation on blood lactate in patients with acute respiratory failure

Objectives: To determine whether mechanical ventilation (MV) may affect blood lactate concentration in patients with acute respiratory failure. Design: Prospective observational study with follow-up to hospital discharge. Setting: A 17-bed medical and coronary intensive care unit in a 650-bed general hospital. Patients: 55 adult patients mechanically ventilated for acute respiratory failure between May 1996 and April 1997 were recruited. Measurements and results: Arterial blood samples for determination of plasma lactate and blood gas analysis were taken just before tracheal intubation on spontaneous breathing, and 20 and 60 min after the initiation of controlled MV. Cuff systemic arterial pressure was measured before tracheal intubation and every 10 min during the first h of MV. Hyperlactatemia (arterial blood lactate ≥ 2 mmol/l) was present in 21 of the 55 patients studied. After 20 min of MV, there was a decrease in blood lactate from 4.74 ± 1.78 to 3.07 ± 1.69 mmol/l (p < 0.01); 40 min later there was a further decrease to 2.63 ± 1.35 mmol/l (p < 0.05). The decrease in blood lactate was also observed in those patients who after starting MV developed systemic arterial hypotension (p < 0.01). In patients with a normal lactate concentration at the entry to the study, lactate remained the same after 60 min on MV (NS). Conclusions: Controlled MV decreases substantially the severity of hyperlactatemia in patients with acute respiratory failure, and any adverse circulatory effects of MV do not alter this beneficial outcome. Received: 16 December 1997 Accepted: 11 June 1998     

The concentrations of somatotropic hormone and insulin in the blood of heart surgery patients with a complicated course of the postoperative period

It has been shown that the course of the early postoperative period in cardiosurgical patients and its outcome is to a great extent related to adequate balance of adaptation hormones, whose levels and changes are determined by the functional state of compensatory-adaptive systems. Patients with favourable outcome of the complicated postoperative period along with synchronous activation of sympathoadrenal system (SAS), hypophyseoadrenal system (HAS) and an elevated somatotropic hormone (STH) level demonstrated adequately high blood insulin content, with the equilibrium in adrenalin/insulin and cortisol/insulin ratios retained, and moderate STH predominance over insulin. In 1/4 of patients with complicated postoperative period and unfavourable outcome an attenuated SAS response was accompanied by excessively high STH, ACTH, cortisol blood content and a lower insulin level, which determined relative insulin insufficiency.     

Increased fructose concentrations in blood and urine in patients with diabetes

OBJECTIVE: To investigate fructose metabolic changes in patients with diabetes. RESEARCH DESIGN AND METHODS: Serum and urinary fructose concentrations were determined in healthy subjects (n = 23) and in nondiabetic (n = 23) and diabetic patients (n = 26). Fructose was measured using our newly developed method, and (13)C(6)-fructose was used as the internal standard. After adding sample to a fixed amount of internal standard, ion-exchange resins and high-performance liquid chromatography pretreatments were performed. Then, the amount of fructose in the sample was measured by gas chromatography-mass spectrometry. RESULTS: Serum fructose concentrations in patients with diabetes (12.0 +/- 3.8 micromol/l) were significantly higher than those in healthy subjects (8.1 +/- 1.0 micromol/l, P < 0.001) and nondiabetic patients (7.7 +/- 1.6 micromol/l, P < 0.001), and daily urinary fructose excretion was significantly greater in patients with diabetes (127.8 +/- 106.7 micromol/day) than in nondiabetic patients (37.7 +/- 23.0 micromol/day, P < 0.001). In patients with diabetes (n = 20), serum fructose concentrations (8.6 +/- 1.8 micromol/l, P < 0.001) and daily urinary fructose excretion (63.4 +/- 63.8 micromol/day, P < 0.01) significantly decreased by week 2 after admission. CONCLUSIONS: The present results differed from those of previous studies in that we found that the serum and urinary fructose concentrations decreased rapidly, concomitant with an improvement in glycemia. Therefore, hyperglycemia was associated with increased serum and urinary fructose concentrations in patients with diabetes.     

Effect of hyperventilation on extracellular concentrations of glutamate,lactate, pyruvate,and local cerebral blood flow in patients with severe traumatic brain injury

OBJECTIVE: To determine the potential adverse effects of brief periods of hyperventilation commonly used for acute neurologic deterioration. DESIGN: Prospective clinical trial. SETTING: University medical school. PATIENTS: Twenty patients with severe traumatic brain injury. INTERVENTIONS: The effect of 30 mins of hyperventilation (mean PaCO2, 24.6 mm Hg) on the extracellular metabolites associated with ischemia, and on local cerebral blood flow was studied by using microdialysis and local cerebral blood flow techniques. Normal appearing brain adjacent to evacuated hemorrhagic contusions or underlying evacuated subdural hematomas was studied. Hyperventilation trials were done 24-36 hrs after injury and again at 3-4 days after injury. Dialysate concentrations of glutamate, lactate, and pyruvate were measured before and for 4 hrs after the hyperventilation trials. MEASUREMENTS AND MAIN RESULTS: At 24-36 hrs, hyperventilation led to a >or=10% increase in the extracellular concentrations of glutamate in 14 of 20 patients, with concentrations in those 14 patients 13.7-395% above baseline; a >or=10% increase in lactate in 7 of 20 patients (11.6-211% above baseline); and a >or=10% increase in the lactate/pyruvate ratio in eight of 20 patients (10.8-227% above baseline). At 3-4 days after injury, ten of 13 patients had an increase in glutamate of >or=10%, while only three of 13 patients had an increase in extracellular lactate and two of 13 patients had an increase in the lactate/pyruvate ratio of this magnitude. The hyperventilation associated increases in extracellular glutamate and lactate concentrations were significant ( P<.05; one-sample Student's -test) at both time points after injury, as was the lactate/pyruvate ratio at 24-36 hrs. A >or=10% decline in local cerebral blood flow was observed with hyperventilation in five of 20 patients at 24-36 hrs (range, 10.2-18.7% below baseline), and in ten of 13 patients studied at 3-4 days (11.3-54% below baseline). There was no correlation with the presence or absence of local CO2 vasoresponsivity and increases in the extracellular metabolites at either the early or late time points. CONCLUSIONS: In brain tissue adjacent to cerebral contusions or underlying subdural hematomas, even brief periods of hyperventilation can significantly increase extracellular concentrations of mediators of secondary brain injury. These hyperventilation-induced changes are much more common during the first 24-36 hrs after injury than at 3-4 days.