Venous Blood Lactate Concentration Research Articles

Workload and spirometry associated with untethered swimming in horses

BackgroundSwimming has been used empirically for rehabilitation and conditioning of horses. However, due to challenges imposed by recording physiological parameters in water, the intensity of free swimming effort is unknown.ObjectivesMeasure the physiological workload associated with untethered swimming in horses.Five fit Arabian endurance horses were assessed while swimming in a 100 m-long indoor pool. Horses were equipped with a modified ergospirometry facemask to measure oxygen consumption (V̇O2) and ventilatory parameters (inspired/expired volumes, VI, VE; peak inspiratory/expiratory flows, PkVI, PkVE; respiratory frequency, Rf; minute ventilation, VE; inspiratory/expiratory durations and ratios, tI, tE, tI/ttot, tE/ttot); and an underwater electrocardiogram that recorded heart rate (HR). Postexercise venous blood lactate and ammonia concentrations were measured. Data are reported as median (interquartile ranges).ResultsHorses showed bradypnea (12 breaths/min (10–16)) for the first 30 s of swimming. V̇O2 during swimming was 43.2 ml/(kg.min) (36.0–56.6). Ventilatory parameters were: VI = 16.7 L (15.3–21.8), VE = 14.7 L (12.4–18.9), PkVI = 47.8 L/s (45.8–56.5), PkVE = 55.8 L/s (38.3–72.5), Rf = 31.4 breaths/min (20.0–33.8), VE = 522.9 L/min (414.7–580.0), tI = 0.5 s (0.5–0.6), tE = 1.2 s (1.1–1.6), tI/ttot = 0.3 (0.2–0.4), tE/ttot = 0.7 (0.6–0.8). Expiratory flow tracings showed marked oscillations that coincided with a vibrating expiratory sound. HR was 178.0 bpm (148.5–182.0), lactate = 1.5 mmol/L (1.0–1.9) and ammonia = 41.0 µmol/L (36.5–43.5).ConclusionsFree (untethered) swimming represents a submaximal, primarily aerobic exercise in horses. The breathing pattern during swimming is unique, with a relatively longer apneic period at the beginning of the exercise and an inspiratory time less than half that of expiration.

Maternal and umbilical cord blood lactate for predicting perinatal death: a secondary analysis of data from a randomized controlled trial

BackgroundIn high resource settings, lactate and pH levels measured from fetal scalp and umbilical cord blood are widely used as predictors of perinatal mortality. However, the same is not true in low resource settings, where much of perinatal mortality occurs. The scalability of this practice has been hindered by difficulty in collecting fetal scalp and umbilical blood sample. Little is known about the use of alternatives such as maternal blood, which is easier and safer to obtain. Therefore, we aimed to compare maternal and umbilical cord blood lactate levels for predicting perinatal deaths.MethodsThis was secondary analysis of data from a randomized controlled trial assessing the effect of sodium bicarbonate on maternal and perinatal outcomes among women with obstructed labour at Mbale regional referral hospital in Eastern Uganda. Lactate concentration in maternal capillary, myometrial, umbilical venous and arterial blood was measured at the bedside using a lactate Pro 2 device (Akray, Japan Shiga) upon diagnosis of obstructed labour. We constructed Receiver Operating Characteristic curves to compare the predictive ability of maternal and umbilical cord lactate and the optimal cutoffs calculated basing on the maximal Youden and Liu indices.ResultsPerinatal mortality risk was: 102.2 deaths per 1,000 live births: 95% CI (78.1–130.6). The areas under the ROC curves were 0.86 for umbilical arterial lactate, 0.71 for umbilical venous lactate, and 0.65 for myometrial lactate, 0.59 for maternal lactate baseline, and 0.65 at1hr after administration of bicarbonate. The optimal cutoffs for predicting perinatal death were 15 0.85 mmol/L for umbilical arterial lactate, 10.15mmol/L for umbilical venous lactate, 8.75mmol/L for myometrial lactate, and 3.95mmol/L for maternal lactate at recruitment and 7.35mmol/L after 1 h.ConclusionMaternal lactate was a poor predictor of perinatal death, but umbilical artery lactate has a high predictive value. There is need for future studies on the utility of amniotic fluid in predicting intrapartum perinatal deaths.

Выбор источника забора крови для измерения уровня лактата у пациентов с септическим шоком

Исходный уровень лактата используется как один из предикторов смертности пациентов с септическим шоком. В опубликованных исследованиях измерялся уровень лактата крови, забранной из различных сосудов, в некоторых ретроспективных исследованиях приводились данные об уровне лактата крови из гетерогенных источников (артерия, центральная вена и периферическая вена). Вопрос, стоящий перед практическими врачами: какие данные имеют лучшую прогностическую ценность, могут ли они заменить друг друга? В наших наблюдениях высокая положительная линейная корреляция обнаружилась между концентрациями лактата артериальной крови и центральной венозной крови (R = 0,895; P < 0,001). Оба показателя имеют удовлетворительную ценность для прогноза исхода лечения. Концентрация лактата в артериальной крови имела несколько лучшую прогностическую ценность по сравнению с его концентрацией в центральной венозной крови.

Electrical-tomographic imaging of physiological-induced conductive response in calf muscle compartments during voltage intensity change of electrical muscle stimulation (vic-EMS)

Objectives. The electrical-tomographic imaging has been achieved for exploring differential tendency of physiological-induced conductive response in calf muscle compartments during voltage intensity change of electrical muscle stimulation (vic-EMS). Approach. In the experiments, the differential tendency of conductivity distribution images σ during vic-EMS were clearly imaged as three responsive muscle compartments, which are called M 1 compartment composed of gastrocnemius muscle, M 2 compartment composed of tibialis anterior, extensor digitorum longus, and peroneus longus muscles, and M 3 compartment composed of soleus muscle. Main results. The differential tendency of spatial-mean conductivity 〈σ〉 M1 is the same as the differential tendency of venous blood flow velocity v bl and blood lactate concentration C bl during vic-EMS by the increased tendency of spatial-mean conductivity difference Δ〈σ〉 M1, venous blood flow velocity difference Δv bl and blood lactate concentration difference ΔC bl . The 〈σ〉 M1 is increased with the increase of voltage intensity from 〈σ pre 〉 M1 = 0.142 [-] to 〈σ l14 〉 M1 = 0.442 [-] (pre: pre-training, l14: voltage level during vic-EMS l = 14) by Δ〈σ l14-pre 〉 M1 = 204.2% (n = 16, p < 0.01). Correspondingly, the v bl and C bl are increased with the increase of voltage intensity by Δv bl l14-pre = 1480.5% (n = 16, p < 0.01) and ΔC bl l14-pre = 230.1% (n = 16, p < 0.01) respectively. Significance: The reason for the differential tendency of increase in <σ> M1 suggests an increase in muscle extracellular volumes during vic-EMS due to the co-effect of venous blood flow velocity and blood lactate metabolism. Based on the conductivity second-order difference images and spatial-mean conductivity second-order difference optimum voltage intensity φ OVI is discussed among sixteen volunteer subjects, which increased with a thicker subcutaneous fat layer.

Lactate Arterial-Central Venous Gradient among COVID-19 Patients in ICU: A Potential Tool in the Clinical Practice.

Objective In physiological conditions, arterial blood lactate concentration is equal to or lower than central venous blood lactate concentration. A reversal in this rate (i.e., higher lactate concentration in central venous blood), which could reflect a derangement in the mitochondrial metabolism of lung cells induced by inflammation, has been previously reported in patients with ARDS but has been never explored in COVID-19 patients. The aim of this study was to explore if the COVID-19-induced lung cell damage was mirrored by an arterial lactatemia higher than the central venous one; then if the administration of anti-inflammatory therapy (i.e., canakinumab 300 mg subcutaneous) could normalize such abnormal lactate a-cv difference. Methods A prospective cohort study was conducted, started on March 25, 2020, for a duration of 10 days, enrolling 21 patients affected by severe COVID-19 pneumonia undergoing mechanical ventilation consecutively admitted to the ICU of the Rimini Hospital, Italy. Arterial and central venous blood samples were contemporarily collected to calculate the difference between arterial and central venous lactate (Delta a-cv lactate) concentrations within 24 h from tracheal intubation (T0) and 24 hours after canakinumab administration (T1). Results At T0, 19 of 21 (90.5%) patients showed a pathologic Delta a-cv lactate (median 0.15 mmol/L; IQR 0.07–0.25). In the 13 patients undergoing canakinumab administration, at T1, Delta a-cv lactate decreased in 92.3% of cases, the decrease being statistically significant (T0: median 0.24, IQR 0.09–0.31 mmol/L; T1: median −0.01, IQR −0.08–0.04 mmol/L; p=0.002). Conclusion A reversed Delta a-cv lactate might be interpreted as one of the effects of COVID-19-related cytokine storm, which could reflect a derangement in the mitochondrial metabolism of lung cells induced by severe inflammation or other uncoupling mediators. In addition, Delta a-cv lactate decrease might also reflect the anti-inflammatory activity of canakinumab. Our preliminary findings need to be confirmed by larger outcome studies.

Venous blood gas parameters, electrolytes, glucose and lactate concentration in sick neonatal foals: Direct venipuncture versus push-pull technique.

Blood collection by indwelling intravenous catheter (IVC) avoids repeated venipuncture, which could cause thrombophlebitis risk, anxiety and pain in patients. To compare blood gas parameters, electrolytes, glucose, lactate and haematocrit concentration obtained from venous blood samples collected via a jugular IVC by push-pull (PP) technique to those obtained by venipuncture in hospitalised foals, at the time of catheter placement (T0) and 24hours after the beginning of intravenous therapy (T24). Prospective observational study. Paired blood samples were drawn from hospitalised foals at T0 and T24. In each foal, one venous blood sample was collected via IVC by the following PP technique: 2.4mL of blood was aspirated and immediately reinfused through the catheter three times consecutively, then 1mL of blood was collected using a 1mL heparinised syringe. Thereafter, another sample was collected by direct venipuncture of the contralateral jugular vein, with an identical 1mL heparinised syringe, with a 1-inch, 20-G needle. All samples were analysed with an automated blood gas analyser within 10minutes of collection. The agreement between the two techniques was assessed by Bland-Altman analysis and intraclass correlation coefficient (ICC). The level of agreement of blood gas values obtained by the two different techniques was high with very small bias and clinically acceptable ICC (>0.907 at T0; >0.794 at T24) for all variables, except for haematocrit (bias -3.52 at T0; -2.44 at T24) and PvO2 at T0 and T24 (ICC 0.669 and 0.733, respectively). Potential sub-clinical catheter-related complications were not investigated by ultrasound or bacterial culture of the catheter; short duration of the study. PP technique appears to be acceptable for collection of blood samples for venous blood gas parameters, as well as electrolytes, glucose and lactate in sick neonatal foals.

Evaluating lactate prognostic value in children suspected of acetaminophen-induced liver failure in Liberia.

The prognostic significance of hyperlactatemia in young children with liver injury suspected to be attributed to repeated supratherapeutic doses of acetaminophen remain understudied. We conducted a retrospective medical chart review including children aged <5 years admitted with hepatocellular injury. The study was conducted in Bardnesville Junction Hospital operated by Médecins Sans Frontières in Monrovia, Liberia. We analyzed 95 children with liver injury in whom a blood lactate measurement on admission was available. Eighty children (84%) were aged <2 years; 49 children (52%) died during hospitalization. The median acetaminophen concentration on admission was 20 mg/L with 60 (70%) children presenting concentrations exceeding 10 mg/L. Median lactate was significantly higher in children who died (10.7 mmol/L; interquartile range (IQR): 8.5-15.7) than those who survived (6.1 mmol/L; IQR: 4.1-8.5), P value < 0.001). The optimal threshold obtained was 7.2 mmol/L with a sensitivity of 84% and specificity 70% (area under curve = 0.80). The previously established thresholds of 3.5 and 4 mmol/L lactate had very low specificity identifying non-survival in children included in this study. In this setting, young children with ALF possibly attributed to acetaminophen toxicity were unlikely to survive if the venous blood lactate concentration exceeded 7.2 mmol/L.

Оценка эффективности применения некоторых лабораторных тестов для мониторинга посттравматического состояния у пациентов с политравмой

Objective Blood serum biochemical parameters (total protein and lactate) were evaluated to monitor posttraumatic condition of polytrauma patients. Material and methods The study included 22 polytrauma patients. Depending on severity of trauma the patients were divided into three groups; in the first group, the ISS being up to 15 (n = 6, mean age, 36.4 ± 13.0 years); in the second, the ISS measuring from 16 to 24 (n = 8, mean age 34.5 ± 11.6 years); and in the third, the ISS being more than 25 (n = 8, mean age 38.6 ± 8.7 years). Venous blood total protein and lactate concentration was measured during posttraumatic period. Results The findings showed intergroup statistically significant differences in the level of total protein with minimal decrease in patients of the first group, and maximum decrease in the third group. No intergroup statistically significant differences were observed in lactate concentration of the study groups. An extent of hypoproteinemia was found to have greater correlation with severity of trauma than lactacidemia. Hypoproteinemia was shown to be caused by intense catabolism during the first 3 days after trauma, and by low protein production for more than 3 days. Conclusion Serum total protein in polytrauma patients was shown to be a more meaningful measure to evaluate severity of polytrauma and monitor therapeutic interventions as compared to lactacidemia.

Arterialized and venous blood lactate concentration difference during different exercise intensities

ObjectiveThe purpose of this study was to investigate the difference between arterialized and venous blood lactate concentrations [La] during constant-load exercises at different intensities. MethodsFifteen physically active men cycled for 30 minutes (or until exhaustion) at the first lactate threshold (LT1), at 50% of the difference between the first and second lactate threshold (TT50%), at the second lactate threshold (LT2), and at 25% of the difference between LT2 and maximal aerobic power output (TW25%). Samples of both arterialized and venous blood were collected simultaneously at rest and every 5 minutes during the exercise. ResultsThe arterialized blood [La] was higher at minute 5 than venous blood [La] for all exercise intensities (p < 0.05). After this period, the arterialized and venous [La] samples became similar until the end of the exercise (p > 0.05). The arterialized-venous difference during the first 10 minutes was greater for the two highest exercise intensities (LT2 and TW25%) compared with the two lowest (LT1 and TT50%, p < 0.05). Thereafter, arterialized-venous difference decreased progressively, reaching values close to zero for all exercise intensities (p > 0.05). ConclusionThese results suggest a delayed lactate appearance in the venous blood, which is accentuated at higher exercise intensities. The lactate measured in arterialized and venous blood is interchangeable only when blood samples are collected at least 10 minutes after the exercise starts.

Cardiopulmonary effects of pleural insufflation with CO2 during two-lung ventilation in dorsally recumbent anesthetized horses

ObjectiveTo record the cardiopulmonary effects of pleural CO2 positive pressure insufflation in anesthetized horses. Study designProspective study. AnimalsSeven horses (mean ± standard deviation, 530.9 ± 68.1 kg) undergoing terminal surgery. MethodsHorses were sedated with xylazine. Anesthesia was induced with ketamine–propofol and maintained with isoflurane, positive pressure ventilation, detomidine infusion, and butorphanol with the horses in dorsal recumbency. Baseline measurements were cardiac output, heart rate, pulmonary and systemic arterial and right atrial blood pressures, body temperature, expired and inspired gas concentrations, and arterial and mixed venous blood gases, electrolytes, glucose, and lactate concentrations. An 18 gauge 6.6 cm needle was inserted into the right pleural cavity midway between the sternum and dorsal midline in the sixth or seventh intercostal space for pleural pressure (PP) measurement. A 14 gauge 18 cm needle placed 5 cm below the previous needle allowed CO2 insufflation into the pleural cavity. All measurements were repeated after: needle insertion, at 2, 5, and 8 mmHg PPs, and after pleural gas removal (GR). Data were compared with baseline using one-way analysis of variance with repeated measures. p < 0.05 was considered significant. ResultsActual PPs were within 1.1 mmHg of the targeted PP. Pulmonary systolic and mean arterial pressures, alveolar dead space to tidal volume ratio, and isoflurane requirements increased at 8 mmHg PP and GR. Cardiac index decreased at 5 mmHg PP. Stroke index decreased at 2 mmHg PP to GR. PaO2 decreased at 5 mmHg PP to GR. PaCO2 increased at 8 mmHg PP and GR. Oxygen delivery decreased at 5 and 8 mmHg PP. Intrapulmonary shunt fraction and lactate concentration increased with GR. Conclusions and clinical relevance:Severe adverse cardiopulmonary effects arise from CO2 positive pressure insufflation into the right hemithorax in dorsally recumbent isoflurane-anesthetized horses. PP should be ≤2 mmHg.

Abstract PR033

Background & Objectives: Increased lactate levels after heart surgery are associated with postoperative morbidity and prolonged length of ICU stay. The aim of our study was to assess the accuracy and applicability of a novel system for continuous lactate monitoring with intravascular microdialysis not requiring calibration in high-risk cardiac surgery. Materials & Methods: Twenty-one patients undergoing elective complex (repair or replacement of two or more valves) or combined (valve and coronary artery) cardiac surgery were enrolled into a prospective observational pilot study. In all patients continuous lactate monitoring was performed using a triple-lumen central venous catheter with an integrated intravascular microdialysis function. Lactate concentration was measured using EirusTM intravascular microdialysis system (Lactatecont) and compared to the lactate concentration in the arterial blood (Lactateart) at 15 stages during the surgery and postoperatively. Results: In total, 432 paired microdialysis–arterial blood gas lactate samples were obtained. After surgery, the concentration of lactate increased significantly peaking at 8 hrs (p < 0.05). The lactate clearance within 8 hrs after peak concentration was 50 (39–63) %. There was a significant correlation between Lactatecont and Lactateart (rho = 0.92, p < 0.0001). Bland-Altman analysis showed a bias (mean difference) ± limits of agreement (±1.96 SD) of 0.09 ± 1.1 mmol/L. In addition, we found a correlation between the lactate concentration in the central venous blood with the central venous-to-arterial carbon dioxide difference (rho = 0.35, p < 0.05) and mean arterial pressure (rho = –0.21, p < 0.001). We did not observe any relationship between lactate concentration, cardiac index, and ScvO2. In patients with postoperative complications, the median and the maximum lactate concentrations were 2.92 (1.75 – 3.50) and 6.75 (4.43 – 7.75) mmol/L, respectively, vs. 2.36 (1.50 – 3.00) and 4.20 (3.95 – 4.87) mmol/L in patients without complications (p = 0.002). Conclusion: Lactate concentration increases significantly after high-risk cardiac surgery. The intravascular microdialysis technique for lactate measurement provides acceptable accuracy and can be used for continuous blood lactate monitoring in open-heart surgery. Disclosure of Interest: None declared

BLOOD GAS, LACTATE, AND HEMATOLOGY EFFECTS OF VENIPUNCTURE TIMING AND LOCATION AFTER MIST-NET CAPTURE OF MOURNING DOVES (ZENAIDA MACROURA), BOAT-TAILED GRACKLES (QUISCALUS MAJOR), AND HOUSE SPARROWS (PASSER DOMESTICUS).

Venous blood gas partial pressures, pH, bicarbonate and lactate concentrations, packed cell volume, white blood cell differential counts, and heterophil/lymphocyte ratios were measured from Mourning Doves (Zenaida macroura), Boat-tailed Grackles (Quiscalus major), and House Sparrows (Passer domesticus). Birds were bled promptly after mist-net capture and banding or following a targeted delay of 45-60 min, in order to assess the impacts of a brief holding period commonly practiced in large-scale bird banding operations. Additionally, effects of venipuncture location (basilic [=ulnar] vein versus jugular vein) were evaluated in male Boat-tailed Grackles sampled promptly after capture and banding. All comparisons were with unpaired samples; no birds were subjected to more than one venipuncture. All three species exhibited moderate improvements in blood gas and acid-base status after the delay, with reductions in lactate concentrations with or without concurrent increases in pH and bicarbonate. Boat-tailed Grackles exhibited an increased proportion of heterophils in the differential white blood cell count following a delay in sampling, suggestive of a stress leukogram. There were no significant differences between basilic and jugular venipuncture results from male Boat-tailed Grackles. Most metabolic, respiratory, and acid-base alterations were minor, but a small number of birds exhibited values (e.g., temperature-corrected pH <7.3, lactate >10 mmol/L) that could be of concern if combined with other adverse conditions. For such birds, a short delay between capture and processing could benefit their blood gas and acid-base status, although loss of time foraging or feeding young and greater activation of the hypophyseal-pituitary-adrenal axis are additional considerations.

Effectiveness of arterial, venous, and capillary blood lactate as a sepsis triage tool in ED patients

ObjectiveWe evaluate the capacity of arterial (ABL), peripheral venous (VBL), and capillary (CBL) blood lactate concentration to early detect the presence of severe sepsis in patients admitted to the emergency department for a septic syndrome. MethodsPatients with signs of sepsis presenting to the emergency department were prospectively enrolled. Blood lactate was measured using a handheld point-of-care analyzer on microsamples of arterial, peripheral venous, and capillary blood. An arterial blood sample was dispatched to the central laboratory as a reference measurement. ResultsA total of 103 patients were enrolled in the study, with 63 patients presenting with a severe sepsis. There was a strong correlation between the point of care and the reference blood lactate measurement. The CBL, VBL, and ABL were all significantly different (3.01 ± 0.29, 2.51 ± 0.21, and 2.03 ± 0.18 mmol/L, respectively; P < .001). The VBL value was the most efficient to detect early the presence of severe sepsis (areas under the receiver operating characteristic curves were 0.85 ± 0.04, 0.76 ± 0.05, and 0.75 ± 0.05 for VBL, ABL, and CBL, respectively; P < .01). Mortality at 28 days was related to the severity of sepsis (28.6% vs 7.5%) and to the number or organ dysfunctions (P < .01). Arterial blood lactate, VBL, and CBL were all significantly associated with the 28th-day mortality. ConclusionsInitial VBL may be used efficiently to assess the severity of sepsis, and it could even be more effective than ABL and CBL to early detect the presence of severe sepsis.

Time Course of Changes in LipopolysaccharideBinding Protein and Lactate in the Blood of Patients with Polytrauma

Objective: to estimate the clinical and prognostic value of the blood levels of lipopolysaharidebinding protein (LPSBP) and lactate in critically ill polytrauma patients. Subjects and methods. An analysis was made of the results of an examination in critical ly ill polytrauma victims who were retrospectively classified in accordance with the 1992 ACCP/SCCM criteria: systemic inflammatory response syndrome (n=18), local infection (n=36), sepsis (n=27), severe sepsis (n=12), and septic shock (n=6). A case was regarded as infection when the source of the latter was established and it was microbiologically verified. The investigators determined serum LPSBP levels by an immunochemiluminescence analyzer (IMMULITE ONE, USA) and venous whole blood lactate concentrations by a Roche Omni S analyzer (Germany). Results. The development of infectious complications was noted in 81% of the polytrauma patients by days 5—7; by days 8—10, 45% were diagnosed as having sepsis whose severe course was characterized by the addition of polyresistant gramnegative microorganisms. An early increase in the concentration and frequency of diagnostic levels of serum LPSBP was ascertained in the polytrauma patients before infection was microbiologically verified. There was a strong direct correlation between lactate and LPSBP levels. Conclusion . The findings suggest that LPS BP and lactate are of diagnostic and prognostic value and may be used as early markers of pyoseptic complications.

Evaluation of serial venous and arterial lactate concentrations in healthy anesthetized sheep undergoing ovariectomy

ObjectiveTo determine if lactate concentrations in jugular venous and auricular arterial blood differ in anesthetized sheep. Study designProspective, controlled experimental study. AnimalsTwelve healthy adult ewes, 4–7 years and weighing 62–77 kg. MethodsJugular venous blood was collected before anesthesia (PreOv) for measurement of lactate concentration, packed cell volume and total protein. Ewes were administered a standard anesthesia protocol. Jugular venous (IntraOv) and auricular arterial (IntraOa) blood samples were obtained 40 minutes after induction of anesthesia, and again in recovery (PostOv and PostOa). An additional blood sample was drawn 6 weeks post-operatively from non-fasted sheep (NF_Lact). Lactate concentrations were compared among PreOv, IntraOv and IntraOa, PostOv and PostOa, and between PreOv and NF_Lact with paired t-test and repeated measure analyses of variance (anova) with PreOv as a covariate (p = 0.05). ResultsIntraOv lactate concentration had decreased from PreOv There were significant differences between arterial and venous IntraO and PostO lactate concentrations. There was no significant difference between IntraO and PostO, or PreOv and NF_Lact. Conclusions and clinical relevanceLactate concentrations were significantly lower in anesthetized sheep compared to non-anesthetized sheep. Lactate concentrations in venous blood were higher than in arterial blood. Therefore, anesthetic status and sampling site should be considered when interpreting lactate concentrations, and the sampling site should be consistent for repeated measurements.

Effects of prolonged exposure to hypobaric hypoxia on oxidative stress, inflammation and gluco-insular regulation: the not-so-sweet price for good regulation.

ObjectivesThe mechanisms by which low oxygen availability are associated with the development of insulin resistance remain obscure. We thus investigated the relationship between such gluco-insular derangements in response to sustained (hypobaric) hypoxemia, and changes in biomarkers of oxidative stress, inflammation and counter-regulatory hormone responses.MethodsAfter baseline testing in London (75 m), 24 subjects ascended from Kathmandu (1,300 m) to Everest Base Camp (EBC;5,300 m) over 13 days. Of these, 14 ascended higher, with 8 reaching the summit (8,848 m). Assessments were conducted at baseline, during ascent to EBC, and 1, 6 and 8 week(s) thereafter. Changes in body weight and indices of gluco-insular control were measured (glucose, insulin, C-Peptide, homeostasis model assessment of insulin resistance [HOMA-IR]) along with biomarkers of oxidative stress (4-hydroxy-2-nonenal-HNE), inflammation (Interleukin-6 [IL-6]) and counter-regulatory hormones (glucagon, adrenalin, noradrenalin). In addition, peripheral oxygen saturation (SpO2) and venous blood lactate concentrations were determined.ResultsSpO2 fell significantly from 98.0% at sea level to 82.0% on arrival at 5,300 m. Whilst glucose levels remained stable, insulin and C-Peptide concentrations increased by >200% during the last 2 weeks. Increases in fasting insulin, HOMA-IR and glucagon correlated with increases in markers of oxidative stress (4-HNE) and inflammation (IL-6). Lactate levels progressively increased during ascent and remained significantly elevated until week 8. Subjects lost on average 7.3 kg in body weight.ConclusionsSustained hypoxemia is associated with insulin resistance, whose magnitude correlates with the degree of oxidative stress and inflammation. The role of 4-HNE and IL-6 as key players in modifying the association between sustained hypoxia and insulin resistance merits further investigation.

Concentração de lactato sérico em ovelhas e cordeiros mestiços (1/2 Suffolk) nascidos em eutocia

O objetivo do estudo foi avaliar a concentração de lactato sanguíneo venoso em ovelhas e em cordeiros neonatos imediatamente após o parto eutócico. Foram utilizadas 14 ovelhas, sendo nove da raça Suffolk e quatro mestiças e 20 cordeiros neonatos sadios (machos e fêmeas). O efeito do sexo, da raça e do número de cordeiros por parto foi investigado, bem como a possível correlação entre a concentração de lactato materno e neonatal. Não houve diferença entre machos e fêmeas, em relação à raça (Suffolk e mestiços), contudo a concentração de lactato foi mais elevada em cordeiros gêmeos ou trigêmeos quando comparado a cordeiros uníparos. Houve correlação positiva entre a concentração materna e a neonatal, sendo que quanto maior a concentração de lactato materno, maior a concentração no cordeiro imediatamente após o parto eutócico. Os resultados do presente estudo fornecem um subsídio por meio do qual se podem comparar os níveis de lactato sanguíneo em cordeiros em estado crítico.

Amniotic fluid and blood lactate concentrations in mares and foals in the early postpartum period

Amniotic fluid (AF) lactate concentration and time-dependent changes in blood lactate concentration in mares after parturition have never been evaluated. In this study, the venous blood lactate concentration of mares and foals during the first 72 h of the postpartum period was assessed, and the concentration of lactate in the AF collected during delivery and the utility of its measurement for evaluating the foal's health were investigated. This prospective observational study was carried out on mares attended at delivery. They were divided into mares delivering healthy (Group 1) and sick (Group 2) foals. The following samples were collected: AF and umbilical blood at delivery, mare's and foal's jugular blood every 12 hours from parturition until 72 h postpartum (T0-T72). Sixty-two mares were enrolled in Group 1 and 19 in Group 2. In Group 2, the survival rate was 68.4%. The median blood lactate of the foals at T0 was 3.60 mmol/L in Group 1 and 5.05 mmol/L in Group 2. The monitoring of the blood lactate concentration showed a significant time-dependent decrease from T24 in the foals (P < 0.01) and from T12 in the mares (P < 0.01). Lactate concentration over time was significantly different between healthy and sick foals (P < 0.01) but not between mares with normal and dystocic delivery (P = 0.08). A significant difference (P = 0.04) was detected as regards AF lactate concentration between Group 1 (median 14.99 mmol/L) and Group 2 (median 12.61 mmol/L). For the first time, AF lactate concentration was evaluated during parturition, and significantly higher levels were found in mares delivering healthy foals. This was an unexpected and very interesting result which warrants further investigation involving a larger number of mares. Additional studies are needed before either mare's blood or AF lactate concentration can be used in a clinical setting.

The Effects of Vasoactive Drugs on Intestinal Functional Capillary Density in Endotoxemic Rats: Intravital Video-Microscopy Analysis

The use of vasoactive drugs to restore arterial blood pressure in patients with septic shock remains a cornerstone of intensive care medicine. However, vasopressors can accentuate the hypoperfusion of the gut during septic shock, allowing bacterial translocation and endotoxemia. In this study, we compared the effects of different vasoactive drugs on intestinal microcirculation and tissue oxygenation, independent of the effects of fluid therapy, in a rat model of endotoxemic shock. Pentobarbital-anesthetized Wistar Kyoto rats were submitted to endotoxemic shock induced by Escherichia coli lipopolysaccharide (2 mg/kg IV). Arterial blood pressure was normalized by a continuous infusion of different vasoactive drugs, including epinephrine, norepinephrine, phenylephrine, dopamine, dobutamine, or a combination of dobutamine and norepinephrine. The functional capillary density (FCD) of the muscular layer of the small intestine was evaluated by intravital video-microscopy. Mesenteric venous blood gases and lactate concentrations were also analyzed. FCD decreased by approximately 25% to 60% after the IV infusion of epinephrine, norepinephrine, and phenylephrine. Administration of dopamine, dobutamine, and the combination of dobutamine and norepinephrine did not induce significant alterations in gut FCD. In addition, the mesenteric venous lactate concentration increased in the presence of phenylephrine and showed a tendency to increase after the administration of epinephrine and norepinephrine, whereas there was no observable increase after the administration of dopamine, dobutamine, and the combination of dobutamine with norepinephrine. This study confirms dissociation of the systemic hemodynamic and microvascular alterations in an experimental model of septic shock. Moreover, the results indicate that the use of dopamine, dobutamine, and dobutamine in combination with norepinephrine yields a protective effect on the microcirculation of the intestinal muscular layer in endotoxemic rats.

Delayed Umbilical Cord Clamping at Birth has Effects on Arterial and Venous Blood Gases and Lactate Concentrations

BJECTIVE: To estimate the influence of delayed umbilical cord clamping at birth on arterial and venous umbilical cord blood gases, bicarbonate (HCO3-), base excess (BE) and lactate in vigorous newborns. SETTING: University hospital. DESIGN: Prospective observational. SAMPLE: Vaginally delivered term newborns. MATERIAL AND METHODS: Umbilical cord arterial and venous blood was sampled repeatedly every 45 seconds (T(0)= time zero; T(45)= 45 seconds, T(90)= 90 seconds) until the cord pulsations spontaneously ceased in 66 vigorous singletons with cephalic vaginal delivery at 36-42 weeks. Longitudinal comparisons were performed with the Wilcoxon signed-ranks matched pairs test. Mixed effect models were used to describe the shape of the regression curves. MAIN OUTCOME MEASURES: Longitudinal changes of umbilical cord blood gases and lactate. RESULTS: In arterial cord blood, there were significant decreases of pH (7.24-7.21), HCO3- (18.9-18.1 mmol/l) and BE (-4.85 to -6.14 mmol/l), and significant increases of PaCO(2) (7.64-8.07 kPa), PO(2) (2.30-2.74 kPa) and lactate (5.3-5.9 mmol/l) from T(0) to T(90), with the most pronounced changes at T(0)-T(45). Similar changes occurred in venous blood pH (7.32-7.31), HCO3- (19.54-19.33 mmol/l), BE (-4.93 to -5.19 mmol/l), PaCO(2) (5.69-5.81 kPa) and lactate (5.0-5.3 mmol/l), although the changes were smaller and most pronounced at T(45)-T(90). No significant changes were observed in venous PO(2). CONCLUSION: Persistent cord pulsations and delayed cord clamping at birth result in significantly different measured values of cord blood acid-base parameters.