Arterial Blood Lactate Concentration Research Articles

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.

Microcirculation assessment of dexmedetomidine constant rate infusion during anesthesia of dogs with sepsis from pyometra: a randomized clinical study

ObjectiveTo compare dexmedetomidine and fentanyl constant rate infusions in anesthetic protocols for septic dogs with pyometra, using microcirculatory, hemodynamic and metabolic variables. Study designRandomized clinical study. AnimalsA total of 33 dogs with pyometra with two or more systemic inflammatory response syndrome variables undergoing ovariohysterectomy. MethodsDogs were randomized into two groups: group DG, dexmedetomidine (3 μg kg–1 hour–1; 17 dogs) and group FG, fentanyl (5 μg kg–1 hour–1; 16 dogs) infused during isoflurane anesthesia and mechanical ventilation. Microcirculation flow index (MFI), total vessel density and De Backer score were assessed using orthogonal polarization spectral imaging at the sublingual site. Heart rate, invasive blood pressure, temperature, arterial blood gas analysis and lactate concentration were obtained at various time points. Variables were recorded at baseline (BL), immediately before (T0), 30 (T30) and 60 (T60) minutes after infusion, and 60 minutes after surgery. Data were analyzed using the Shapiro-Wilk test. To compare variables between groups, the unpaired Student t test was used. Comparison between evaluation time points was performed with two-way anova for repeated measures. Where statistical significance was detected, the Bonferroni post hoc test was used. ResultsMFI was significantly higher in group FG at T30. Mean arterial pressure at T30 was higher in group DG (89 ± 15 mmHg) than in group FG (72 ± 13 mmHg). Lactate concentrations were not significantly different between groups at each time point. Both groups had similar clinical outcomes (mortality, extubation time and occurrence of hypotension and bradyarrhythmias). Conclusions and clinical relevanceDexmedetomidine (3 μg kg–1 hour–1) without a loading dose can be included in the maintenance of anesthesia in dogs with pyometra and sepsis without compromising microcirculation and hemodynamic values when compared with fentanyl (5 μg kg–1 hour–1).

Effects of intravenous ethyl pyruvate on cardiopulmonary variables and quality of recovery from anesthesia in horses

ObjectiveTo determine the effects of intravenous ethyl pyruvate, an anti-inflammatory with putative benefits in horses with endotoxemia, on cardiopulmonary variables during anesthesia and the quality of anesthetic recovery. Study designRandomized, crossover, blinded experimental design. AnimalsA total of six healthy Standardbred geldings, aged 13 ± 3 years and weighing 507 ± 66 kg (mean ± standard deviation). MethodsHorses were anesthetized for approximately 90 minutes on two occasions with a minimum of 2 weeks apart using xylazine for sedation, ketamine and diazepam for induction, and isoflurane in oxygen for maintenance. Lactated Ringer’s solution (LRS; 10 mL kg–1 hour–1) was administered during anesthesia. Treatments were randomized and administered starting approximately 30 minutes after induction of anesthesia and infused over 60 minutes: LRS (1 L) or ethyl pyruvate (150 mg kg–1 in 1 L LRS). Invasive arterial pressures, heart rate, respiratory rate and end-tidal carbon dioxide tensions were recorded every 5 minutes for the duration of anesthesia. Arterial blood gases, glucose and lactate concentrations were measured every 20 minutes. Anesthetic recovery was video recorded, stored, and subsequently rated by two individuals blinded to treatments. Total recovery time, time to extubation, number of attempts and time to sternal recumbency, number of attempts to stand and time to stand were recorded. Quality of recovery was analyzed. Data between treatments and within a treatment were assessed using two-way repeated-measures anova and a Pearson correlation coefficient, significant at p < 0.05. ResultsAll horses completed the study. No significant differences were detected between the ethyl pyruvate and LRS treatments for either the cardiopulmonary variables or quality of recovery from anesthesia. Conclusions and clinical relevanceThe results suggest that intravenous ethyl pyruvate can be administered to healthy anesthetized horses with minimal impact on the cardiopulmonary variables studied or the quality of recovery from anesthesia.

Does severe hyperlactatemia during cardiopulmonary bypass predict a worse outcome?

IntroductionThe aim of the current study was to evaluate the impact of increased blood lactate levels during cardiopulmonary bypass (CPB) on immediate results in patients who underwent open heart surgery. Materials and methodsWe performed a retrospective single-center study on 1290 patients. Adult cardiac surgical patients who underwent valve surgery, coronary artery bypass graft, combined procedure, adult congenital anomalies and aortic surgery were enrolled. Patients with associated comorbidities such as liver dysfunction, hemodynamic instability before surgery were excluded. Arterial blood lactate concentration was measured immediately after weaning from CPB and evaluated together with clinical data and outcomes including in hospital mortality. Patients were classified into 3 groups according to their peak arterial lactate level: group I [normal lactatemia, lactate ˂ 2 mmol/l (n = 749)], group II [mild hyperlactatemia, lactate 2–5 mmol/l (n = 489)], group III [severe hyperlactatemia, lactate ˃ 5 mmol/l (n = 52)] ResultsWhen comparing outcomes across the 3 groups, severe hyperlactatemia was correlated with worse outcomes including higher in-hospital mortality, low output cardiac syndrome, postoperative renal insufficiency, myocardial infarction, red blood cell transfusion (RBC) transfusion, prolonged mechanical ventilation and longer intensive care unit (ICU) stay hours. ConclusionBlood lactate level above 5 mmol/l and more during CPB is associated with higher in-hospital mortality rate and postoperative complications. More attention must be given to correct the common abnormalities conditions inherent of CPB in order to conduct adequate tissue perfusion and reduce the risk of hyperlactatemia.

General health condition of patients hospitalized after an incident of in-hospital or out-of hospital sudden cardiac arrest with return of spontaneous circulation.

BackgroundSudden cardiac arrest (SCA) is one of the main reasons for admission to the intensive care unit (ICU), which influences discharge in a good neurological state.HypothesisTo analyze patients who had recovery of spontaneous circulation (ROSC) during hospitalization in the ICU using the Glasgow Outcome Scale (GOS).MethodsThe study group comprised 78 patients after SCA (35 after out‐of‐hospital cardiac arrest [OHCA] and 43 after in‐hospital cardiac arrest [IHCA]) with ROSC who were admitted to the ICU of Regional Hospital No. 5 in Sosnowiec from January 1, 2016 to December 31, 2016. GOS was used to assess neurological status. Basic anthropological data, with, arterial blood pH, lactate concentration (LAC), and catecholamine treatment were also collected.ResultsIn the study group, 32.1% (n = 25/78) of patients survived until ICU discharge and 30.8% (n = 24/78) until discharge from the hospital. SCA in cardiac mechanism was more common in OHCA than in the IHCA group (OHCA vs. IHCA: 85.7% vs. 62.8%, p = .02). There was no statistically significant difference between the two groups for neurological status assessed using GOS. There was no statistically significant difference between LAC or arterial blood pH and survival to ICU discharge, survival to hospital discharge, or mortality. The need for using catecholamines increased the mortality rate (GOS 1) (p < .001).ConclusionsMost patients after RSOC were assigned to a group other than GOS 1, and 25% of all subjects belonged to GOS 4–5. Treatment with catecholamines was more common in patients who do not survive hospital or ICU discharge.

Performance, Metabolic, and Neuromuscular Consequences of Repeated Wingates in Hypoxia and Normoxia: A Pilot Study.

Compared with normoxia, repeated short (5-10 s) sprints (>10 efforts) with incomplete recovery (≤30 s) in hypoxia likely cause substantial performance reduction accompanied by larger metabolic disturbances and magnitude of neuromuscular fatigue. However, the effects of hypoxia on performance of repeated long (30 s) "all-out" efforts with near complete recovery (4.5 min) and resulting metabolic and neuromuscular adjustments remain unclear. The intention was to compare acute performance, metabolic, and neuromuscular responses across repeated Wingates between hypoxia and normoxia. On separate visits, 6 male participants performed 4 × 30-second Wingate efforts with 4.5-minute recovery in either hypoxia (fraction of inspired oxygen: 0.145) or normoxia. Responses to exercise (muscle and arterial oxygenation trends, heart rate, and blood lactate concentration) and the integrity of neuromuscular function in the knee extensors were assessed for each exercise bout. Mean (P = .80) and peak (P = .92) power outputs, muscle oxygenation (P = .88), blood lactate concentration (P = .72), and perceptual responses (all Ps > .05) were not different between conditions. Arterial oxygen saturation was significantly lower, and heart rate higher, in hypoxia versus normoxia (P < .001). Maximal voluntary contraction force and peripheral fatigue indices (peak twitch force and doublets at low and high frequencies) decreased across efforts (all Ps < .001) irrespective of conditions (all Ps > .05). Despite heightened arterial hypoxemia and cardiovascular solicitation, hypoxic exposure during 4 repeated 30-second Wingate efforts had no effect on performance and accompanying metabolic and neuromuscular adjustments.

Low Microcirculatory Perfused Vessel Density and High Heterogeneity are Associated With Increased Intensity and Duration of Lactic Acidosis After Cardiac Surgery with Cardiopulmonary Bypass.

Lactic acidosis after cardiac surgery with cardiopulmonary bypass is common and associated with an increase in postoperative morbidity and mortality. A number of potential causes for an elevated lactate after cardiopulmonary bypass include cellular hypoxia, impaired tissue perfusion, ischemic-reperfusion injury, aerobic glycolysis, catecholamine infusions, and systemic inflammatory response after exposure to the artificial cardiopulmonary bypass circuit. Our goal was to examine the relationship between early abnormalities in microcirculatory convective blood flow and diffusive capacity and lactate kinetics during early resuscitation in the intensive care unit. We hypothesized that patients with impaired microcirculation after cardiac surgery would have a more severe postoperative hyperlactatemia, represented by the lactate time-integral of an arterial blood lactate concentration greater than 2.0 mmol/L. We measured sublingual microcirculation using incident darkfield video microscopy in 50 subjects on intensive care unit admission after cardiac surgery. Serial measurements of systemic hemodynamics, blood gas, lactate, and catecholamine infusions were recorded each hour for the first 6 h after surgery. Lactate area under the curve (AUC) was calculated over the first 6 h. The lactate AUC was compared between subjects with normal and low perfused vessel density (PVD < 18 mm/mm2), high microcirculatory heterogeneity index (MHI > 0.4), and low vessel-by-vessel microvascular flow index (MFIv < 2.6). Thirteen (26%) patients had a low postoperative PVD, 20 patients (40%) had a high MHI, and 26 (52%) patients had a low MFIv. Patients with low perfused vessel density had higher lactate AUC compared with subjects with a normal PVD (22.3 [9.4-31.0] vs. 2.6 [0-8.8]; P < 0.0001). Patients with high microcirculatory heterogeneity had a higher lactate AUC compared with those with a normal MHI (2.5 [0.1-8.2] vs. 13.1 [3.7-31.1]; P < 0.001). We did not find a difference in lactate AUC when comparing high and low MFIv. Low perfused vessel density and high microcirculatory heterogeneity are associated with an increased intensity and duration of lactic acidosis after cardiac surgery with cardiopulmonary bypass.

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.

Relationship between platelet/lymphocyte ratio and prognosis of patients with septic acute kidney injury: A pilot study.

Background:To explore the potential role of the platelet/lymphocyte ratio (PLR) as a prognostic marker in septic patients with acute kidney injury (AKI) and to provide theoretical evidence for the epidemiological study of the prognosis of patients with septic AKI in its early stage.Methods:A pilot study was conducted. A logistic regression analysis was conducted to screen the risk factors, and the selected factors were performed using multiple logistic regression analysis; a Receiver Operating Characteristic curve was used to determine the optimal cutoff value of the PLR and then to calculate the sensitivity and specificity of the PLR ratio.Results:Mechanical ventilation, platelet count, PLR, and arterial blood lactate concentration have a correlation with sepsis (p < 0.05). An elevated PLR is significantly associated with a worse prognosis of sepsis-induced AKI (higher mortality).Conclusion:The PLR might be an effective factor in predicting a worse prognosis of septic AKI patients.

Associations between oxygen delivery and cardiac index with hyperlactatemia during cardiopulmonary bypass.

ObjectiveMetabolism management plays an essential role during cardiopulmonary bypass (CPB). There are different metabolic management devices integrated to heart–lung machines; the most commonly used and accepted metabolic target is indexed oxygen delivery (DO2i) (280 mL/min/m2) and cardiac index (CI) (2.4 L/min/m2), which can be managed independently or according to other metabolic parameters. Our objective was to compare lactate production during CPB procedures using different metabolic management: DO2i in relation to indexed oxygen extraction ratio (O2ERi) and CI in relation to mixed venous oxygen saturation (SvO2).MethodsData on 500 CPB procedures were retrospectively collected in a specialized regional tertiary cardiac surgery center in Italy between September and 2012 and November 2019. In group A, the DO2i with 280 mL/min/m2 target in relation to O2ERi 25% was used; in group B, CI with 2.4 L/min/m2 target in relation to SvO2 75% was used. During CPB, serial arterial blood gas analyses with blood lactate and glucose determinations were obtained. Hyperlactatemia (HL) was defined as a peak arterial blood lactate concentration >3 mmol/L. The postoperative outcome of patients with or without HL was compared.ResultsEight pre- and intraoperative factors were found to be significantly associated with peak blood lactate level during CPB at univariate analysis. HL (>3 mmol/L) was detected in 15 (6%) patients of group A and in 42 (16.8%) patients of group B (P = .022); hyperglycemia (>160 mg/dL) was found in 23 (9.2%) patients of group A and in 53 (21.2%) patients of group B (P = .038). Patients with HL during CPB had a significant increase in serum creatinine value, higher rate of prolonged mechanical ventilation time and intensive care unit stay. A cutoff of DO2i <270 mL/min/m2 in relation to O2ERi >35% in group A and a cutoff of CI <2.4 L/min/m2 in relation to SvO2 <65% in group B were found to have a positive predictive value of 80% and 75% for HL, respectively. A cutoff of DO2i >290 mL/min/m2 in relation to O2ERi 24% in group A and a cutoff of CI >2.4 L/min/m2 in relation to SvO2 >75% in group B were found to have a negative predictive value of 78% and 62% for HL, respectively.ConclusionsThis retrospective observational analysis showed that management of DO2i in relation to O2ERi was 16% more specific in terms of negative predictive value for HL during CPB compared with the use of CI in relation to SvO2. Group A reported a significant reduction in the incidence of intraoperative lactate peak, correlated with postoperative reduction of serum creatinine value, mechanical ventilation time, and intensive care unit stay, compared with group B.

Prognostic value of difference between peripheral venous and arterial partial pressure of carbon dioxide in patients with septic shock: a pilot study

To evaluate the prognostic value of the difference between peripheral venous and arterial partial pressure of carbon dioxide in patients with septic shock following early resuscitation. This prospective study was conducted among the patients with septic shock treated in our department during the period from May, 2017 to May, 2018. Peripheral venous, peripheral arterial and central venous blood samples were collected simultaneously and analyzed immediately at bedside after 6-h bundle treatment. Arterial blood lactate concentration (Lac) and the arterial (PaCO2), peripheral venous (PpvCO2) and central venous partial pressure of carbon dioxide (PcvCO2) were recorded. The differences between PpvCO2 and PaCO2 (Ppv-aCO2) and between PcvCO2 and PaCO2 (Pcv-aCO2) were calculated. Pearson correlation analysis was used to test the agreement between Pcv-aCO2 and Ppv-aCO2. Multivariable logistic regression analysis was performed to analyze the possible risk factors for 28-day mortality, and the receiver-operating characteristic curve (ROC) was plotted to assess the prognostic values of these factors for 28-day mortality. A total of 62 patients were enrolled in this study, among who 35 survived and 27 died during the 28-day period. Compared with the survivor group, the patients died within 28 days showed significantly higher Acute Physiology and Chronic Health Evaluation Ⅱ (APACHE Ⅱ) score (24.2±6.0 vs 20.5±4.9, P=0.011), sequential organ failure assessment (SOFA) score (14.9±4.7 vs 12.2±4.5, P=0.027), PcvaCO2 (5.5±1.6 vs 7.1±1.7, P &lt; 0.001), PpvaCO2 (7.1±1.8 vs 10.0±2.7, P &lt; 0.001), and arterial lactate level (3.3±1.2 vs 4.2±1.3, P=0.003) after 6-h bundle treatment. Pearson correlation analysis showed that Ppv-aCO2 was significantly correlated with Pcv-aCO2 (r=0.897, R2= 0.805, P &lt; 0.001). Multiple logistic regression analysis identified Ppv-aCO2 (β=0.625, P=0.001, OR=1.869, 95% CI: 1.311-2.664) and lactate level (β=0.584, P=0.041, OR=1.794, 95%CI: 1.024-3.415) as the independent risk factors for 28-day mortality. The maximum area under the ROC (AUC) of Ppv-aCO2 was 0.814 (95%CI: 0.696- 0.931, P &lt; 0.001), and at the best cut- off value of 9.05 mmHg, Ppv-aCO2 had a sensitivity of 70.4% and a specificity of 88.6% for predicting 28-day mortality. The AUC of lactate level was 0.732 (95%CI: 0.607-0.858, P=0.002), and its sensitivity for predicting 28-day mortality was 70.4% and the specificity was 74.3% at the best cut-off value of 3.45 mmol/L; The AUC of Pcv-aCO2 was 0.766 (95%CI: 0.642-0.891, P &lt; 0.001), and its sensitivity was 66.7% and the specificity was 80.0% at the best cut-off value of 7.05 mmHg. A high Ppv-aCO2 after early resuscitation of septic shock is associated with poor outcomes. Ppv-aCO2 is well correlated with Pcv-aCO2 and can be used as an independent indicator for predicting 28-day mortality in patients with septic shock.

Dose-related effects of dexmedetomidine on immunomodulation and mortality to septic shock in rats.

Dexmedetomidine has already been used in septic patients as a new sedative agent, few studies have examined its effects on immunomodulation. Therefore, the authors have designed a controlled experimental study to characterize the immunomodulation effects of dexmedetomidine in the cecal ligation and puncture (CLP) model in rats. After CLP, 48 Wistar rats were randomly allocated into four groups: (1) CLP group; (2) small-dose treatment group (2.5 μg·kg-1·h-1); (3) medium-dose treatment group (5.0 μg·kg-1· h-1); and (4) large-dose treatment group (10.0 μg·kg-1·h-1). HLA-DR and plasma cytokine (IL-4, IL-6, IL-10 and TNF-α) levels were measured, and the mean arterial blood pressure (MAP), heart rate (HR), arterial blood gases, lactate concentrations and mortality were also documented. The HLA-DR level, inflammatory mediator levels, MAP and HR had no obvious changes among Dexmedetomidine treatment groups (DEX groups). Compared with the CLP group, the DEX groups exhibited decreased HLA-DR levels (Pgroup=0.0202) and increased IL-6 production, which was increased at 3 h (P= 0.0113) and was then attenuated at 5 h; additionally, the DEX groups exhibited decreased HR (P<0.001) while maintaining MAP (Pgroup=0.1238), and remarkably improving lactate (P<0.0001). All of these factors led to a significant decrease in the mortality, with observed rates of 91.7%, 66.7%, 25% and 18% for the CLP, DEX2.5, DEX5.0, DEX10.0 groups, respectively. Dexmedetomidine treatment in the setting of a CLP sepsis rat model has partially induced immunomodulation that was initiated within 5 h, causing a decreased HR while maintaining MAP, remarkably improving metabolic acidosis and improving mortality dose-dependently.

Efficacy of stroke volume variation combined with low central venous pressure-directed fluid therapy in patients undergoing liver cancer resection

Objective To evaluate the efficacy of stroke volume variation(SVV)combined with controlled low central venous pressure(CLCVP)-directed fluid therapy in the patients undergoing liver cancer resection. Methods Seventy American Society of Anesthesiologists physical status Ⅰ or Ⅱ patients, aged 40-60 yr, with body mass index of 20-25 kg/m2, scheduled for elective liver cancer resection under general anesthesia, were divided into 2 groups(n=35 each) using a random number table: routine fluid replacement group(R group) and SVV combined with CLCVP-guided fluid replacement group(SC group). In R group, routine fluid replacement included compensatory volume expansion, physiological requirement, cumulative loss, continued loss (intraoperative blood loss) and 3rd space losses, maintaining mean arterial pressure>70 mmHg, central venous pressure<4 cmH2O and heart rate <100 bpm.Central venous pressure was maintained <4 cmH2O and SVV <12% during operation in SC group.The operation time, total amount of crystalloid and colloid solution infused, urine volume and development of intraoperative hypotension and bradycardia were recorded.Blood samples from the left radial artery and central vein were collected before anesthesia induction and at the end of operation for measurement of the blood lactate concentration, and the oxygen supply index, oxygen consumption index and oxygen uptake rate were calculated.Blood samples from the ulnar vein were collected before anesthesia induction and at the end of operation for determination of serum β2-microglobulin concentrations.The development of intraoperative adverse cardiovascular events was recorded, and the occurrence of postoperative complications was observed. Results Compared with R group, the total amount of crystalloid solution infused was significantly decreased, the total amount of colloid solution infused and urine volume were increased, the incidence of intraoperative hypotension and bradycardia was decreased, oxygen supply index, oxygen consumption index and oxygen uptake rate were increased at the end of operation, and the lactate concentration in arterial blood, serum β2-microglobulin concentration and rate of postoperative pulmonary infection were decreased in SC group (P<0.05). Conclusion SVV combined with CLCVP-directed fluid therapy produces better efficacy than routine fluid replacement in the patients undergoing liver resection. Key words: Stroke volume; Central venous pressure; Liver neoplasms

Cardiovascular Drift during Training for Fitness in Patients with Metabolic Syndrome.

The health benefits of a training program are largely influenced by the exercise dose and intensity. We sought to determine whether during a training bout of continuous versus interval exercise the workload needs to be reduced to maintain the prescribed target heart rate (HR). Fourteen obese (31 ± 4 kg·m) middle-age (57 ± 8 yr) individuals with metabolic syndrome, underwent two exercise training bouts matched by energy expenditure (i.e., 70 ± 5 min of continuous exercise [CE] or 45 min of interval exercise, high-intensity interval training [HIIT]). All subjects completed both trials in a randomized order. HR, power output (W), percent dehydration, intestinal and skin temperature (TINT and TSK), mean arterial pressure, cardiac output (CO), stroke volume (SV), and blood lactate concentration (La) were measured at the initial and latter stages of each trial to assess time-dependent drift. During the HIIT trial, power output was lowered by 30 ± 16 W to maintain the target HR, whereas a 10 ± 11 W reduction was needed in the CE trial (P < 0.05). Energy expenditure, CO, and SV declined with exercise time only in the HIIT trial (15%, 10%, and 13%, respectively). During HIIT, percent dehydration, TINT, and TSK increased more than during the CE trial (all P = 0.001). Mean arterial pressure and La were higher in HIIT without time drift in any trial. Our findings suggests that while CE results in mild power output reductions to maintain target HR, the increasingly popular HIIT results in marked reductions in power output, energy expenditure, and CO (21%, 15%, and 10%, respectively). HIIT based on target HR may result in lower than expected training adaptations because of workload adjustments to avoid HR drift.

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.

Intestinal barrier dysfunction and its related factors in patients with sepsis

Objective: To investigate the relationship between related factors of intestinal barrier dysfunction in patients with sepsis or septic shock and severity of the condition. Methods: A prospective observational study was conducted in 31 sepsis patients, 28 septic shock patients, and 21 postoperative patients without sepsis (control group) who were admitted to intensive care unit (ICU) of General Hospital of Ningxia Medical University between November 2015 and June 2016. Blood samples were collected from the patients within 24 hours following admission to ICU. D-lactic acid and endotoxin levels were measured by enzymatic method, serum high-sensitivity C-reactive protein (hsCRP) level by immune scatter turbidimetry. An arterial blood gas (ABG) measurement was carried out every 8 hours within the first 24 hours after admission to ICU, and average arterial blood lactate levels were calculated. Acute Physiology and Chronic Health Evaluation Ⅱ (APACHE Ⅱ) score, Sequential Organ Failure Assessment (SOFA) score of the patients within 24 hours following ICU admission were recorded. The patients with sepsis or septic shock were followed up for 28 days after admission to ICU, and divided into survival group (n=44) and death group (n=15). The patients with sepsis or septic shock were divided into two groups according to the site of infection, i. e. intra-abdominal infection group (n=37) and extra-abdominal infection group (n=22). Results: (1) In the control, sepsis, and septic shock groups, D-lactic acid [mg/L, M(P25, P75) ] were 11.68(7.49, 14.92), 19.78 (12.25, 34.85), and 32.45 (16.03, 46.95), respectively; endotoxin levels [U/L, M(P25, P75)] were 10.60(7.59, 13.39), 16.12(10.09, 20.23), and 17.31(14.09, 23.77), respectively. The levels of serum D-lactic acid and endotoxin in the patients with sepsis or septic shock were significantly higher than those in the control group (all P<0.01); while no statistically significant differences existed in these two indices between the sepsis and septic shock groups (both P>0.05). There were no statistically significant differences in serum D-lactic acid and endotoxin levels between the intra-abdominal infection group and the extra-abdominal infection group [20.07(14.70, 38.97)vs 21.65 (14.53, 56.56)mg/L; 17.23(13.38, 20.85)vs 17.17(9.93, 20.81)U/L; both P>0.05]. There were no statistically significant differences in levels of serum D-lactic acid and endotoxin between the survival group and the death group [21.65(15.11, 39.00) vs 19.78(14.41, 80.93)mg/L; 17.09(12.62, 20.42) vs 19.26(13.22, 26.27)U/L, both P>0.05]. (2) In the sepsis and septic shock patients, serum D-lactate level was significantly related to mean arterial blood lactate concentration, APACHE Ⅱ score, and SOFA score in the first 24 hours after admission to ICU (r=0.499, 0.447, 0.469, all P<0.01); serum endotoxin level was correlated with hsCRP, APACHE Ⅱ score, and SOFA score (r=0.224, 0.388, 0.393, all P<0.05). (3) Multivariate linear regression analysis showed that D-lactic acid level was independently associated with average arterial blood lactate concentration as well as with SOFA score(R2=0.34, F=19.91, P<0.01), and endotoxin was independently associated with only SOFA score(R2=0.14, F=12.68, P<0.01). Conclusions: Regardless of the site of infection, patients with sepsis or septic shock often have intestinal barrier injury, which is correlated with the severity of disease, but does not independently affect patient outcome. Tissue hypoperfusion in the early stage of sepsis may be one of the causes of intestinal barrier injury.

Effect of therapeutic hypercapnia on cerebral oxygen metabolism in patients undergoing thoracoscopic surgery in beach chair position

Objective To evaluate the effect of therapeutic hypercapnia on cerebral oxygen metabolism in the patients undergoing thoracoscopic surgery in beach chair position (BCP). Methods Sixty patients of both sexes, aged 18-32 yr, with body mass index of 19-24 kg/m2, of American Society of Anesthesiologists physical status Ⅰ or Ⅱ, scheduled for elective bilateral thoracic sympathectomy performed via a thoracoscope, were divided into control group (group C) and hypercapnia group (group H), with 30 patients in each group using a random number table.After induction of anesthesia, all the patients in both groups were tracheally intubated and mechanically ventilated using the ventilation regimen low tidal volume intermittent positive pressure ventilation combined with low level of positive end-expiratory pressure (5 cmH2O), maintaining arterial carbon dioxide partial pressure (PaCO2) at 35-45 mmHg.PaCO2 was maintained at 45-55 mmHg by adjusting the respiratory rate after the patients were placed in BCP in group H. Anesthesia was maintained with target-controlled infusion of propofol and intermittent intravenous boluses of rocuronium and sufentanil.Bispectral index value was maintained at 45-55.Before anesthesia induction (baseline), at 5 min after intubation, and at 5, 10, 15 and 20 min after the patients were placed in BCP, blood samples were taken from the radial artery and jugular bulb for blood gas analysis, jugular venous bulb oxygen saturation was measured, and arteriovenous blood O2 content difference, cerebral O2 extraction rate, and venous to arterial blood lactate concentration difference were calculated. Results Compared with group C, PaCO2 and jugular venous bulb oxygen saturation were significantly increased, and arteriovenous blood O2 content difference and cerebral O2 extraction rate were significantly decreased at at 5, 10, 15 and 20 min after the patients were placed in BCP in group H (P 0.05). Conclusion Therapeutic hypercapnia can improve the cerebral oxygen metabolism in the patients undergoing thoracoscopic surgery in BCP. Key words: Hypercapnia; Posture; Oxygen consumption; Brain

Effects on indicators of tissue perfusion in dogs anesthetized with isoflurane at two multiples of the minimum alveolar concentration.

To investigate the effects of isoflurane anesthesia administered at 2 multiples of the minimum alveolar concentration (MAC) on tissue perfusion in dogs. 8 healthy young adult Beagles. A randomized crossover design was used. Dogs were anesthetized with isoflurane at 1.5 or 2.0 times the MAC for 2 hours, a 7-day washout period was provided, and dogs were reanesthetized with the alternate treatment. Various physiologic variables were monitored before anesthesia (baseline), at 20-minute intervals during anesthesia, and after anesthetic recovery. Variable values were compared between MAC multiples by means of repeated-measures ANOVA, with the Tukey test used for multiple comparisons. During anesthesia, mean arterial blood pressure, cardiac output, and mixed venous oxygen saturation were significantly greater when isoflurane was administered at 1.5 versus 2.0 times the MAC. Cardiac output gradually increased during anesthesia at 1.5 times but not at 2.0 times the MAC. Arterial blood lactate concentration did not differ between MAC multiples at any point; however, this concentration decreased with increasing anesthetic duration at both MAC multiples. Oxygen delivery differed between MAC multiples, and oxygen consumption differed from baseline during anesthesia at 2.0 times the MAC. Oxygen extraction was higher at 2.0 versus 1.5 times the MAC. Heart rate differed between MAC multiples only after anesthetic recovery. Isoflurane anesthesia impaired tissue perfusion in dogs, but these changes would not be clinically relevant with oxygen delivery at 100%. Peripheral tissue perfusion was maintained or improved with time.

Assessing the influence of mechanical ventilation on blood gases and blood pressure in rattlesnakes

ObjectiveTo characterize the impact of mechanical positive pressure ventilation on heart rate (HR), arterial blood pressure, blood gases, lactate, glucose, sodium, potassium and calcium concentrations in rattlesnakes during anesthesia and the subsequent recovery period. Study designProspective, randomized trial. AnimalsTwenty one fasted adult South American rattlesnakes (Crotalus durissus terrificus). MethodsSnakes were anesthetized with propofol (15 mg kg−1) intravenously, endotracheally intubated and assigned to one of four ventilation regimens: Spontaneous ventilation, or mechanical ventilation at a tidal volume of 30 mL kg−1 at 1 breath every 90 seconds, 5 breaths minute−1, or 15 breaths minute−1. Arterial blood was collected from indwelling catheters at 30, 40, and 60 minutes and 2, 6, and 24 hours following induction of anesthesia and analyzed for pH, PaO2, PaCO2, and selected variables. Mean arterial blood pressure (MAP) and HR were recorded at 30, 40, 60 minutes and 24 hours. ResultsSpontaneous ventilation and 1 breath every 90 seconds resulted in a mild hypercapnia (PaCO2 22.4 ± 4.3 mmHg [3.0 ± 0.6 kPa] and 24.5 ± 1.6 mmHg [3.3 ± 0.2 kPa], respectively), 5 breaths minute−1 resulted in normocapnia (14.2 ± 2.7 mmHg [1.9 ± 0.4 kPa]), while 15 breaths minute−1 caused marked hypocapnia (8.2 ± 2.5 mmHg [1.1 ± 0.3 kPa]). Following recovery, blood gases of the four groups were similar from 2 hours. Anesthesia, independent of ventilation was associated with significantly elevated glucose, lactate and potassium concentrations compared to values at 24 hours (p < 0.0001). MAP increased significantly with increasing ventilation frequency (p < 0.001). HR did not vary among regimens. Conclusions and clinical relevanceMechanical ventilation had a profound impact on blood gases and blood pressure. The results support the use of mechanical ventilation with a frequency of 1–2 breaths minute−1 at a tidal volume of 30 mL kg−1 during anesthesia in fasted snakes.

Marine mammals and Emperor penguins: a few applications of the Krogh principle.

The diving physiology of aquatic animals at sea began 50 years ago with studies of the Weddell seal. Even today with the advancements in marine recording and tracking technology, only a few species are suitable for investigation. The first experiments were in McMurdo Sound, Antarctica. In this paper are examples of what was learned in Antarctica and elsewhere. Some methods employed relied on willingness of Weddell seals and emperor penguins to dive under sea ice. Diving depth and duration were obtained with a time depth recorder. Some dives were longer than an hour and as deep as 600 m. From arterial blood samples, lactate and nitrogen concentrations were obtained. These results showed how Weddell seals manage their oxygen stores, that they become reliant on a positive contribution of anaerobic metabolism during a dive duration of more than 20 min, and that nitrogen blood gases remain so low that lung collapse must occur at about 25 to 50 m. This nitrogen level was similar to that determined in elephant seals during forcible submersion with compression to depths greater than 100 m. These results led to further questions about diving mammal's terminal airway structure in the lungs. Much of the strengthening of the airways is not for avoiding the "bends," by enhancing lung collapse at depth, but for reducing the resistance to high flow rates during expiration. The most exceptional examples are the small whales that maintain high expiratory flow rates throughout the entire vital capacity, which represents about 90% of their total lung capacity.