Total Carbon Dioxide Content Research Articles

Reference limits for blood gas analysis performed from coccygeal vessels of multiparous Holstein dairy cows: Effects of stage of lactation and season of sampling

Blood gas analysis is a great support to the diagnostic process of critically ill patients. Its correct application to the medicine of dairy cows depends on the availability of specific reference intervals that are still difficult to find in the literature. They may vary according to the type of blood sampled, animals' age and production stage, and climatic conditions. This study aimed at calculating the reference limits for some blood gas parameters in the blood collected from the coccygeal vessels of multiparous Holstein dairy cows. This site of sampling implies the risk of withdrawing blood of unknown origin (venous, arterial, or mixed), but has a high practical interest for the easy and quick performance and the minimal animal restraint required. Data from 379 cows were used, and reference limits were produced for pH, partial pressure of carbon dioxide (pCO2), bicarbonate concentration (HCO3), total carbon dioxide concentration (tCO2), oxygen saturation (sO2), hemoglobin (Hb), hematocrit (Hct), base excess (BE), glucose, Na, K, and ionized calcium (iCa). The effects of stage of lactation (5 to 60 vs. > 60 DIM) and season of sampling (cold vs. hot) were investigated, and specific reference limits were produced for each variable and each level of the factors whenever a significant effect was detected. The pH, sO2, K, and iCa were not influenced by season or stage of lactation. All the other blood gas parameters were significantly affected by season of sampling, and Hb, Hct, glucose, and Na were also affected by stage of lactation. Reference limits provided in this study are specific to the site of sampling (coccygeal vessels) and the animal category considered. Further studies are needed to produce reference intervals for other blood gas parameters, cow categories, and blood types.

Assessment of the adaptive capacity of Morada Nova ewes with different coat coloration.

Coat color is a factor affecting heat tolerance in tropical ruminant and a particular coat color can determine which is more resilient to environmental changes. The aim of this study was to measure the level of adaptation of Morada Nova sheep with different coat color by using an Adaptability Index (AI). Adult ewes were used, including two different coat colors of Morada Nova sheep (red and white) with mean of body weight of 28.02 ± 5.70kg and 31.47 ± 3.41kg, respectively. Physiology parameters, hematology, electrolytes, acid-base status, mineral, renal functions, metabolites, enzymes, and proteins were measured. AI was designed using a multivariate approach (principal component analysis) to "weigh" the influence of each variable in the animal responses. The variables more important for adaptive aspects of Red Morada Nova were: haematology, electrolytes and acid-base status. The hemoglobin (HG), mean corpuscular hemoglobin (MCH), mean corpuscular hemoglobin concentration (MCHC), sodium (Na+), oxygen pressure (PO2), glucose (GLU) and albumin (ALB) were significantly higher in Red Morada Nova sheep and hydrogen carbonate (HCO3), base excess (BE), total carbon dioxide concentration (TCO2) and URE were significantly higher in the white phenotype. The variables more important for adaptive aspects of White Morada Nova sheep were: (K+), total protein (TP), PO2, HG, cholesterol (CHO), rectal temperature (RT) and glucose (GLU). Both phenotypes showed a high adaptation level, however, a higher value was generated for the Red Morada Nova sheep (81.97). This study concludes that both phenotypes of the Morada Nova sheep breed are well adapted to the climatic condition of the Brazilian tropical region using different adaptive mechanisms.

PCO 2 Gradient Between Inlet and Outlet Blood of Extracorporeal Respiratory Support Is a Reliable Marker of CO 2 Elimination.

Our objective was to assess the relationship between the pre-/post-oxygenator gradient of the partial pressure of carbon dioxide (∆ EC PCO 2 ; dissolved form) and CO 2 elimination under extracorporeal respiratory support. All patients who were treated with veno-venous extracorporeal membrane oxygenation and high-flow extracorporeal CO 2 removal in our intensive care unit over 18 months were included. Pre-/post-oxygenator blood gases were collected every 12 h and CO 2 elimination was calculated for each pair of samples (pre-/post-oxygenator total carbon dioxide content in blood [ ct CO 2 ] × pump flow [extracorporeal pump flow {Q EC }]). The relationship between ∆ EC PCO 2 and CO 2 elimination, as well as the origin of CO 2 removed. Eighteen patients were analyzed (24 oxygenators and 293 datasets). Each additional unit of ∆ EC PCO 2 × Q EC was associated with an increase in CO 2 elimination of 5.2 ml (95% confidence interval [CI], 4.7-5.6 ml; p < 0.001). Each reduction of 1 ml STPD/dl of CO 2 across the oxygenator was associated with a reduction of 0.63 ml STPD/dl (95% CI, 0.60-0.66) of CO 2 combined with water, 0.08 ml STPD/dl (95% CI, 0.07-0.09) of dissolved CO 2 , and 0.29 ml STPD/dl (95% CI, 0.27-0.31) of CO 2 in erythrocytes. The pre-/post-oxygenator PCO 2 gradient under extracorporeal respiratory support is thus linearly associated with CO 2 elimination; however, most of the CO 2 removed comes from combined CO 2 in plasma, generating bicarbonate.

Evaluation of yeast-based additives, as an alternative to ionophores, on rumen fermentation of ruminant diets using an in vitro gas production system

IntroductionThe study aimed to assess yeast-based additives' effects, as monensin alternatives, on rumen fermentation parameters, greenhouse gas emissions, and ruminal kinetics of ruminant diets using an in vitro system. Three experiments were conducted, each individually evaluating escalating levels of three yeast-based additives.MethodsThree experiments were designed: Experiment 1 evaluated prebiotic blend 1—yeast culture [Saccharomyces cerevisiae (Scer)], beta-glucans, fructooligosaccharides, galactooligosaccharides, and mannanoligosaccharides; Experiment 2 investigated prebiotic blend 2—beta-glucan fractions and mannanoligosaccharides from Scer; Experiment 3 examined yeast cells—hydrolyzed, inactivated, and spray-dried yeast (Scer) cells. Uniform experimental design and procedures were employed across the three experiments. Each experiment had six treatments: monensin (Rumensin®, 25 mg/kg DM) as positive control, and yeast additive levels (0, 533, 1,067, 1,600, and 2,133 mg/kg on DM basis) added to ruminant diets (60% corn silage and 40% concentrate). An in vitro gas production (GP) system with 50 AnkomRF bottles assessed total GP (at 24 and 48 hours), kinetics, fermentation profiles, methane (CH4), and carbon dioxide (CO2) concentrations. Comparison with monensin utilized Dunnett’s test (5%). Yeast additive levels were analyzed for linear and quadratic responses.ResultsIn Experiment 1, the 1,600 mg/kg yeast additive had lower concentrations of propionate, isobutyrate, valerate, and branched-chain volatile fatty acids (BCVFAs), and a higher acetate concentration and acetate-to-propionate ratio than monensin. In Experiment 2, the 1,600 mg/kg yeast additive led to lower total VFA and isovalerate concentrations than monensin. Additionally, compared to the 1,067 mg/kg yeast additive, monensin showed lower isovalerate concentration and higher NH3-N concentration. In Experiment 3, the 533 mg/kg yeast additive resulted in lower valerate and BCVFA concentrations, and higher CH4 and CO2 concentrations than monensin. Monensin had lower total VFA, butyrate, and acetate-to-propionate ratio, and higher propionate concentration compared to the 2,133 mg/kg yeast additive.DiscussionCollectively, these findings suggest yeast-based additives could be monensin alternatives, enhancing animal nutrient utilization efficiency and contributing to improved livestock sustainability.

Venous Blood Gas and Acid-base Values in Captive Asian Elephants (Elephas maximus)

Background: Blood gas and acid base values are very much essential for health assessment and disease diagnosis of captive elephants especially when clinical signs were nonspecific and other diagnostic techniques may not be available for immediate applications. Region specific normal healthy animal profile is valuable in health care planning for captive elephants. The aim of this study was to assess and evolve the baseline reference values for Blood gas and acid base parameters in captive Asian elephants raised in the Tamil Nadu State of India. Methods: A total of 46 venous blood samples were analyzed for blood gas and acid base values such as partial pressure of oxygen (PvCO2), partial pressure of carbon-dioxide (PvO2), oxygen saturation (SvO2), total carbon dioxide content (TvCO2), Bicarbonate and Base excess (BEecf), bicarbonate (HCO3-) and pH by using i-STAT®1 hand held analyzer. Results: The mean±SE, lower and upper value, 95% and 99% of confidence interval of the pH, PvCo2, PvO2, TvCo2, BEecf, HCO3- , SvO2, Lactate were assessed. As the elephants in this study were apparently healthy, these range of values could well serve as a reference range for captive Asian elephants.

A white-box model for real-time simulation of acid–base balance in blood plasma

Maintaining an optimal acid base is important for the patient. The theory underlying acid–base balance can be challenging for clinicians and educators. These considerations justify creating simulations that include realistic changes to the partial pressure of carbon dioxide, pH, and bicarbonate ion concentration in a range of conditions. Our explanatory simulation application requires a model that derives these variables from total carbon dioxide content and runs in real time. The presented model is derived from the Stewart model, which is based on physical and chemical principles, and takes into account the effects of weak acids and strong ions on the acid–base balance. An inventive code procedure allows for efficient computation. The simulation results match target data for a broad range of clinically and educationally relevant disturbances of the acid–base balance. The model code meets the real-time goals of the application and can be applied in other educational simulations. Python model source code is made available.

Total Carbon Dioxide (TCO2) Concentrations in Thoroughbred and Quarter Racehorses in Louisiana.

The TCO2 (total carbon dioxide) test is performed on the blood of racehorses as a means of combatting the practice of administering alkalizing agents. This study evaluated serum TCO2 concentrations and factors influencing concentration of TCO2 in Thoroughbred and Quarter Horses. The normality of data were evaluated with a Shapiro-Wilk test. Mann-Whitney tests and Kruskal-Wallis tests were used against different effects. When a fixed effect was detected, Dunn's post-hoc comparisons were performed. The median pre-race serum TCO2 concentration (32.20 mmol/L (interquartile range (IQR): 30.80-33.50)) was higher than that of post-race samples (26.70 mmol/L (IQR: 24.55-29.25)) (P < .0001). The median TCO2 concentrations in pre-race samples were different between Thoroughbred (32.40 mmol/L (IQR: 30.90-33.60)) and Quarter Horses (31.30 mmol/L (IQR: 30.00-32.50)) (P < .0001). The median pre-race TCO2 concentrations were 32.75 (IQR: 31.40-33.90), 31.40 (IQR: 29.80-32.80), 32.50 (IQR: 31.20-33.88), and 31.60 (IQR 30.00-32.70) mmol/L in racehorses at Fair Grounds, Louisiana Downs, Delta Downs, and Evangeline Downs racetracks, respectively (P < .0001). The total serum TCO2 concentrations in Thoroughbred and Quarter Horse racehorses were affected by seasonal temperature variation (P < .0001). A smaller sample size was available for post-race samples (n=205) and Quarter Horse pre-race samples (n=351). The results of this study indicated that the breed, seasonal temperature variation, pre-race or post-race sampling, and track location are strongly correlated to total TCO2 concentrations. It was not clear whether the statistically significant differences in TCO2 levels among racetracks in Louisiana were due to location of racetracks and/or seasonal temperature variation.

Physicochemical Analysis of Mixed Venous and Arterial Blood Acid-Base State in Horses at Core Temperature during and after Moderate-Intensity Exercise.

Simple SummaryThe purposes of the present study were to determine the effect of core body temperature on acid-base variables and determine the origins of acid-base changes in the arterial and mixed venous blood of horses during exercise and recovery. Moderate intensity exercise resulted in an increase in body temperature that, in addition to exercise, affected acid-base status and gas partial pressures. Moderate intensity exercise resulted in a mild alkalosis that had markedly different origins in arterial blood than in mixed venous blood, and this was affected by the increase in core temperature during exercise and its resolution during recovery. In order to fully understand how acid-base status changes during exercise and recovery, it is importance to quantify the changes in both arterial and mixed venous blood, with adjustment to core temperature. Acid-base assessments using jugular vein blood samples are limited in comparison.The present study determined the independent contributions of temperature, strong ion difference ([SID]), total weak acid concentration ([Atot]) and PCO2 to changes in arterial and mixed venous [H+] and total carbon dioxide concentration ([TCO2]) during 37 min of moderate intensity exercise (~50% of heart rate max) and the first 60 min of recovery. Six horses were fitted with indwelling carotid and pulmonary artery (PA) catheters, had PA temperature measured, and had blood samples withdrawn for immediate analysis of plasma ion and gas concentrations. The increase in core temperature during exercise (+4.5 °C; p < 0.001) significantly (p < 0.05) increased PO2, PCO2, and [H+], but without a significant effect on [TCO2] (p > 0.01). The physicochemical acid-base approach was used to determine contributions of independent variables (except temperature) to the changes in [H+] and [TCO2]. In both arterial and venous blood, there was no acidosis during exercise and recovery despite significant (p < 0.05) increases in [lactate] and in venous PCO2. In arterial blood plasma, a mild alkalosis with exercise was due to primarily to a decrease in PCO2 (p < 0.05) and an increase in [SID] (p < 0.1). In venous blood plasma, a near absence of change in [H+] was due to the acidifying effects of increased PCO2 (p < 0.01) being offset by the alkalizing effects of increased [SID] (p < 0.05). The effect of temperature on PO2 (p < 0.001) resulted in an increased arterio-venous PO2 difference (p < 0.001) that would facilitate O2 transfer to contracting muscle. The simultaneous changes in the PCO2 and the concentrations of the other independent acid-base variables (contributions from individual strong and weak ions as manifest in [SID] and [Atot]) show complex, multilevel control of acid-base states in horses performing even moderate intensity exercise. Correction of acid-base variables to core body temperature presents a markedly different physiological response to exercise than that provided by variables measured and presented at an instrument temperature of 37 °C.

Chemical Ecology of Oviposition Dynamics in Drosophila suzukii (Diptera: Drosophilidae).

Massive economic damage by spotted-wing drosophila (SWD), Drosophila suzukii, results from their unique egg laying behavior wherein a gravid fly pierces a ripening fruit to lay a number of eggs. Gravid SWD flies employ a complex suite of behaviors to find a fruit with the optimum firmness and chemistry. We investigated chemosensory cues potentially contributing to the oviposition behavior of SWD. In a series of experiments, we studied how the fruit ripeness and the underlying volatile chemistry influence oviposition. We tested the comparative attraction of three common fruits implicated in oviposition and determined raspberries to be most attractive in the trap choice assays that strictly measured olfactory preference. Since SWD oviposit in ripening fruits and appear to avoid the overripe fruit, we further evaluated the effect of ripeness on gravid fly attraction. Overripe fruits were significantly more attractive compared to the ripe fruits. The trap choice assays were repeated in an olfactory T-maze paradigm that provided a complex odor environment, potentially experienced by the gravid flies, and the results were mostly comparable. Since our behavioral paradigms indicated a clear olfactory preference for specific ripeness stages (ripe and overripe), we analyzed the constituent volatile odorants from the three ripening stages, revealing discrete odor profiles. Finally, we quantified the total soluble sugars and carbon dioxide concentrations from field-collected raspberries in underripe, ripe, and overripe conditions, revealing that the overripe stage is the most sugar-rich. Together, our results indicate unique chemosensory adaptations in gravid SWD flies for successfully exploiting optimal oviposition resources.

Effect of time and sample size on serum bicarbonate testing

A number of preanalytical factors have been described as affecting the measurement of plasma total carbon dioxide concentration. Here we present the effect of using varying blood volumes on bicarbonate concentration.

Evaluation of homeothermy, acid-base and electrolytic balance of black goats and ewes in an equatorial semi-arid environment.

The aim of this study was to investigate the influence of environmental conditions and species on thermoregulatory responses, acid-base and electrolyte balance of black goats and ewes in an equatorial semi-arid environment. Ten Canindé goats and seven Morada Nova ewes with black coat color, all multiparous, aged between 2 and 3 years, non-lactating, non-pregnant, and body weight (BW) of 22.84±4.17kg for goats and 22.60±3.18kg for ewes were used in this study. Air temperature (AT) and relative humidity (RH) were measured. Respiratory rate (RR), Rectal temperature (RT), sweating rate (SR), hydrogen potential (pH), partial pressure of carbon dioxide (PCO2), venous oxygen pressure (PO2), bicarbonate (HCO3), base excess (BE), total carbon dioxide concentration (TCO2), venous oxygen saturation (SO2), sodium (Na+) and potassium (K+) were recorded. Animal species (caprine and ovine) and environmental conditions (Thermoneutral condition, TC and Heat condition, HC) were considered as fixed effects. Univariate and multivariate analysis techniques were used. Differences were observed between the two environmental conditions. Significant changes in all thermoregulatory responses for goats and ewes were observed according to the environmental condition effect. The general means of the species showed that only SR was high in ewes (P<0.05), following a reverse change when compared to goat SR. For the environmental condition effect, only the blood pH of goats did not change under HC (P<0.05), while the BE and TCO2 did not change for ewes. The general means of PCO2, HCO3, BE, TCO2 and SO2 were higher in ewes compared to goats. For electrolytic balance, Na+demonstrated elevations in HC. Brazilian black goats and ewes raised in an equatorial semi-arid environment tend to have particular homeothermy, acid-base and electrolytic balance which mostly depend on the environmental conditions they are raised. The results support the changes in physiological mechanisms between black goats and ewes; however, both are locally adapted.

FC 052ACID-BASE BALANCE DURING IN-SERIES EXTRACORPOREAL CARBON DIOXIDE REMOVAL AND CONTINUOUS VENOVENOUS HEMOFILTRATION: PREDICTIONS FROM A MATHEMATICAL MODEL

Abstract Background and Aims Critically ill acute kidney injury (AKI) patients may require treatment by extracorporeal carbon dioxide removal (ECCO2R) devices to allow protective or ultraprotective mechanical ventilation and avoid hypercapnic acidosis. Continuous venovenous hemofiltration (CVVH) and ECCO2R devices can be arranged in series to form a single extracorporeal circuit; such a circuit has been proposed to be optimal, based carbon dioxide removal efficacy, if the ECCO2R device is placed proximal to the CVVH device (Allardet-Servent et al, Crit Care Med 43:2570-2581, 2015). Method We developed a mathematical model of whole-body, acid-base balance during extracorporeal therapy using in-series ECCO2R and CVVH devices for treatment of mechanically ventilated AKI patients. Equilibrium acid-base chemistry in blood was assumed as reported previously (Rees and Andreassen, Crit Rev Biomed Eng 33:209-264, 2005). Published clinical data from Allardet-Servent et al of mechanically ventilated (6 mL/kg predicted body weight or PBW) AKI patients treated by CVVH without ECCO2R were used to adjust model parameters to fit plasma levels of arterial partial pressure of carbon dioxide (PaCO2) and arterial plasma bicarbonate concentration ([HCO3]). The effects of applying ECCO2R at an unchanged tidal volume and a reduced tidal volume (4 mL/kg PBW) on PaCO2 and [HCO3] were then simulated assuming carbon dioxide removal rates from the ECCO2R device measured in the clinical study (91 mL of CO2/min when ECCO2R was proximal and 72 mL of CO2/min when CVVH was proximal). Results Agreement of model predictions with the clinical data was good, and model predictions were relatively independent of the in-series position of the devices (see Table). Total carbon dioxide removal from the CVVH device via ultrafiltration predicted by the model was lower after applying ECCO2R at both the unchanged tidal volume (25 mL of CO2/min when ECCO2R was proximal and 39 mL of CO2/min when CVVH was proximal) and the reduced tidal volume (30 mL of CO2/min when ECCO2R was proximal and 44 mL of CO2/min when CVVH was proximal). The reduced removal of total carbon dioxide via ultrafiltration when ECCO2R was proximal resulted from the lower total carbon dioxide concentration in blood entering the CVVH device. Thus, independent of the in-series position of the devices, the magnitude of this difference in total carbon dioxide removal by the CVVH device (14 mL of CO2/min) approximately cancels out the relative greater efficacy of the ECCO2R device (19 mL of CO2/min). Conclusion The described mathematical model has quantitative accuracy. It suggests that overall acid-base balance when using ECCO2R and CVVH devices in a single, combined extracorporeal circuit will be similar, independent of their in-series position.

Study on effect CO2 diluent on fuel cоmbustion in methane-oxygen combustion chambers

Studying closed gas turbine cycles on supercritical carbon dioxide is currently a promising issue in the development of power energy sector in terms of increasing energy efficiency and minimizing greenhouse gas emissions into the atmosphere. Combustion of methane with oxygen in the combustion chamber occurs not in the nitrogen environment, but in the environment of carbon dioxide, that is the working fluid of the cycle, which is an inhibitor of chemical reactions. A large mass content of such a diluent of the reaction mixture in the volume of the chamber leads to the risks of significant chemical underburning, efficiency decrease of the combustion chamber and the cycle as a whole. The aim of the research is to study the kinetic parameters of the combustion of methane with oxygen in a supercritical CO2 diluent medium to ensure reliable and stable combustion of fuel by assessing the degree of the inhibitory effect of CO2 and determining its permissible amount in the active combustion zone of the combustion chamber. The research method is a numerical simulation of turbulent-kinetic processes of methane combustion in the combustion chamber using the reduced methane combustion mechanism. Ansys Fluent software package has been used. The authers have studied the impact of CO2 diluent on fuel cоmbustion in methane-oxygen combustion chambers. It is found that the combustor flame stabilization takes place if the content of СО2 diluent supplied to the mixture with oxidizer is 0,46–0,5 of mass fraction; additional СО2 diluent forms local low temperature zones which slow down the combustion process. When this happens, adding cooling СО2 into the flame stabilization zone should be eliminated. The study has found that no more than 20 % of the total carbon dioxide content should be supplied to the combustion chamber; to stabilize the flame and reduce its length, it is necessary to install blades to swirl the fuel and oxidizer mixed with CO2 at the inlet of the combustion chamber; CO2 supply for cooling should be carried out not less than 130 mm away from the burner mouth.

Association of Pre-ESRD Serum Bicarbonate with Post-ESRD Mortality in Patients with Incident ESRD

Background: Serum bicarbonate or total carbon dioxide (CO₂) concentrations decline as chronic kidney disease (CKD) progresses and rise after dialysis initiation. While metabolic acidosis accelerates the progression of CKD and is associated with higher mortality among patients with end stage renal disease (ESRD), there are scarce data on the association of CO₂ concentrations before ESRD transition with post-ESRD mortality. Methods: A historical cohort from the Transition of Care in CKD (TC-CKD) study includes 85,505 veterans who transitioned to ESRD from October 1, 2007, through March 31, 2014. After 1,958 patients without follow-up data, 3 patients with missing date of birth, and 50,889 patients without CO₂ 6 months prior to ESRD transition were excluded, the study population includes 32,655 patients. Associations between CO₂ concentrations averaged over the last 6 months and its rate of decline during the 12 months prior to ESRD transition and post-ESRD all-cause, cardiovascular (CV), and non-CV mortality were examined by using hierarchical adjustment with Cox regression models. Results: The cohort was on average 68 ± 11 years old and included 29% Black veterans. Baseline concentrations of CO₂ were 23 ± 4 mEq/L, and median (interquartile range) change in CO₂ were −1.8 [−3.4, −0.2] mEq/L/year. High (≥28 mEq/L) and low (<18 mEq/L) CO₂ concentrations showed higher adjusted mortality risk while there was no clear trend in the middle range. Consistent associations were observed irrespective of sodium bicarbonate use. There was also a U-shaped association between the change in CO₂ and all-cause, CV, and non-CV mortality with the lowest risk approximately at −2.0 and 0.0 mEq/L/year among sodium bicarbonate nonusers and users, respectively, and the highest mortality was among patients with decline in CO₂ >4 mEq/L/year. Conclusion: Both high and low pre-ESRD CO₂ levels (≥28 and <18 mEq/L) during 6 months prior to dialysis transition and rate of CO₂ decline >4 mEq/L/year during 1 year before dialysis initiation were associated with greater post-ESRD all-cause, CV, and non-CV mortality. Further studies are needed to determine the optimal management of CO₂ in patients with advanced CKD stages transitioning to ESRD.

Relationship Between Serum Total Carbon Dioxide Concentration and Bicarbonate Concentration in Patients Undergoing Peritoneal Dialysis.

BackgroundFew studies have assessed the relationship between serum total carbon dioxide (CO2) and bicarbonate ion (HCO3−) concentration in patients undergoing peritoneal dialysis. We determined the agreement between serum total CO2 and HCO3− concentration and the diagnostic accuracy of serum total CO2 for the prediction of low (HCO3− <24 mEq/L) and high (HCO3− ≥24 mEq/L) bicarbonate concentrations in patients on peritoneal dialysis.MethodsWe collected 245 samples of venous blood from 51 patients on peritoneal dialysis. Independent factors that correlated with the HCO3− concentration were analyzed using multiple linear regression analysis. The diagnostic accuracy of serum total CO2 was evaluated by receiver operating characteristic (ROC) curve analysis and a 2×2 table. Agreement between serum total CO2 and HCO3− concentration was assessed by Bland-Altman analysis.ResultsSerum total CO2 was independently correlated with HCO3− concentration (β = 0.354, p < 0.001). The area under the curve of serum total CO2 for the identification of low and high bicarbonate concentrations was 0.909. The diagnostic accuracy of serum total CO2 for the prediction of low and high bicarbonate concentrations was: sensitivity, 91.5%; specificity, 74.7%; positive predictive value, 53.5%; negative predictive value, 96.5%; and accuracy, 78.8%. Bland-Altman analysis showed a moderate agreement between serum total CO2 and HCO3− concentration.ConclusionSerum total CO2 correlated closely with the HCO3− concentration in patients undergoing peritoneal dialysis. Serum total CO2 might be useful for predicting low and high bicarbonate in peritoneal dialysis patients.

Large-Format Additive Manufacturing and Machining Using High-Melt-Temperature Polymers. Part I: Real-Time Particulate and Gas-Phase Emissions.

The literature on emissions during material extrusion additive manufacturing with 3-D printers is expanding; however, there is a paucity of data for large-format additive manufacturing (LFAM) machines that can extrude high-melt-temperature polymers. Emissions from two LFAM machines were monitored during extrusion of six polymers: acrylonitrile butadiene styrene (ABS), polycarbonate (PC), high-melt-temperature polysulfone (PSU), poly(ether sulfone) (PESU), polyphenylene sulfide (PPS), and Ultem (poly(ether imide)). Particle number, total volatile organic compound (TVOC), carbon monoxide (CO), and carbon dioxide (CO2) concentrations were monitored in real-time. Particle emission rate values (no./min) were as follows: ABS (1.7 × 1011 to 7.7 × 1013), PC (5.2 × 1011 to 3.6 × 1013), Ultem (5.7 × 1012 to 3.1 × 1013), PPS (4.6 × 1011 to 6.2 × 1012), PSU (1.5 × 1012 to 3.4 × 1013), and PESU (2.0 to 5.0 × 1013). For print jobs where the mass of extruded polymer was known, particle yield values (g-1 extruded) were as follows: ABS (4.5 × 108 to 2.9 × 1011), PC (1.0 × 109 to 1.7 × 1011), PSU (5.1 × 109 to 1.2 × 1011), and PESU (0.8 × 1011 to 1.7 × 1011). TVOC emission yields ranged from 0.005 mg/g extruded (PESU) to 0.7 mg/g extruded (ABS). The use of wall-mounted exhaust ventilation fans was insufficient to completely remove airborne particulate and TVOC from the print room. Real-time CO monitoring was not a useful marker of particulate and TVOC emission profiles for Ultem, PPS, or PSU. Average CO2 and particle concentrations were moderately correlated (r s = 0.76) for PC polymer. Extrusion of ABS, PC, and four high-melt-temperature polymers by LFAM machines released particulate and TVOC at levels that could warrant consideration of engineering controls. LFAM particle emission yields for some polymers were similar to those of common desktop-scale 3-D printers.

Relationship between serum total carbon dioxide concentration and bicarbonate concentration in patients undergoing hemodialysis

BackgroundFew studies have investigated the relationship between serum total carbon dioxide (CO2) concentration and bicarbonate ion (HCO3-) concentration in patients undergoing hemodialysis. We determined the agreement and discrepancy between serum total CO2 and HCO3- concentrations and the diagnostic accuracy of serum total CO2 for the prediction of low (HCO3- < 24 mEq/L) and high (HCO3- ≥ 24 mEq/L) bicarbonate concentrations in hemodialysis patients.MethodsOne hundred forty-nine arteriovenous blood samples from 84 hemodialysis patients were studied. Multiple linear regression analysis was used to determine factors correlated with HCO3- concentration. Diagnostic accuracy of serum total CO2 was evaluated using receiver operating characteristic curve analysis and a 2 × 2 table. Agreement between serum total CO2 and HCO3- concentrations was assessed using Bland-Altman analysis.ResultsSerum total CO2 concentration was closely correlated with HCO3- concentration (β = 0.858, P < 0.001). Area under the curve of serum total CO2 for the identification of low and high bicarbonate concentrations was 0.989. Use of serum total CO2 to predict low and high bicarbonate concentrations had a sensitivity of 100%, specificity of 50.0%, positive predictive value of 96.5%, negative predictive value of 100%, and accuracy of 96.6%. Bland-Altman analysis showed moderate agreement between serum total CO2 and HCO3- concentrations. Discrepancies between HCO3- and serum total CO2 concentrations (serum total CO2 - HCO3- ≤ -1) were observed in 89 samples.ConclusionSerum total CO2 concentration is closely correlated with HCO3- concentration in hemodialysis patients. However, there is a non-negligible discrepancy between serum total CO2 and HCO3- concentrations.

Optimizing serum total carbon dioxide concentration during short and nocturnal frequent hemodialysis using lactate as dialysate buffer base.

Definitive clinical studies to determine the optimal dialysate lactate concentration to prescribe during frequent hemodialysis when using the NxStage System One dialysis delivery system at low dialysate flow rates have not been reported. We used clinical data from patients who transferred from in-center thrice-weekly hemodialysis (ICHD) to daily home hemodialysis using the NxStage System One and the H+ mobilization model to calculate acid generation rates in patient sub-groups during the FREEDOM study. Assuming those acid generation rates were representative, we then predicted using the H+ mobilization model the effect of using dialysate lactate concentrations of 40 and 45 mEq/L on predialysis serum total carbon dioxide (tCO2 ) concentrations in patients who transfer from ICHD to short and nocturnal frequent hemodialysis prescriptions used in current clinical practice; the prescriptions evaluated varied by treatment frequency, dialysate volume per treatment, and treatment times. With frequencies of four to six treatments per week and treatment times of 170 to 210 minutes per treatment, the effect of dialysate lactate concentration was primarily dependent on weekly dialysate volume. For weekly dialysate volumes of 150 to 160 L per week, use of dialysate lactate concentrations of 45 mEq/L, but not 40 mEq/L, resulted in an increase of predialysis serum tCO2 concentration. When longer treatment times typical of nocturnal frequent hemodialysis were evaluated, model predictions showed that the use of dialysate lactate concentration of 45 mEq/L may not be appropriate for many patients because of excessive increases in predialysis serum tCO2 concentration. Reducing dialysate volume from 60 to 30 L may limit the increase in predialysis serum tCO2 concentration when patients transfer from ICHD to nocturnal frequent hemodialysis. Predictions from the H+ mobilization model show that dialysate lactate concentration and weekly dialysate volume are the primary prescription parameters for optimizing predialysis serum tCO2 concentration during short and nocturnal frequent hemodialysis.

Evaluation of nutrient content and in-vitro gas production of complete feed based on corn stover (Zea mays) supplemented by mimosa powder and myristic acid

&lt;p class="MDPI17abstract"&gt;&lt;strong&gt;Objective: &lt;/strong&gt;The purpose of this research was to evaluate the effect supplementation of mimosa powder as a source of condensed tannins and a single fatty acid, myristic acid, in a complete feed based on corn stover (&lt;em&gt;Zea mays&lt;/em&gt;) using the in-vitro gas production method. This research has been carried out at the Animal Nutrition and Food Laboratory, Faculty of Animal Husbandry, Brawijaya University. The time of the research was conducted in August until December 2019.&lt;/p&gt;&lt;p class="MDPI17abstract"&gt;&lt;strong&gt;Methods: &lt;/strong&gt;The experimental design used randomized complete block design by ANOVA consisting four treatments and three replications which were P1= a complete feed based on corn stover (&lt;em&gt;Zea mays&lt;/em&gt;) as control Diet (CD) (40% corn stover + 60 % concentrate), P2= (CD) + Mimosa Powder(MP) 1.5 %/kg DM + myristic acid (MA)2% /kg DM, P3= CD + MP 1.5 % /kg DM + MA 3% /kg DM, and P4= CD + MP 1.5 %/kg DM + MA 4 %/kg DM.&lt;/p&gt;&lt;p class="MDPI17abstract"&gt;&lt;strong&gt;Results: &lt;/strong&gt;The results showed that the treatments affected total gas production (p&amp;lt;0.01). The highest value for total gas production was found in P1 (86.67 ml/500 mg DM) and the lowest was found in P3 (73.30 ml/500 mg DM). The results showed that gas production decreased concurrently with the increase of MA level. In vitro methane gas and carbon dioxide production was showed different (p&amp;lt;0.05) from the control treatment. The lowest concentration of methane production was in P4 (82863.07 ppm) and the highest concentration was in treatment P1 86530.89 ppm. The highest total carbon dioxide content was P1 (436711.57 ppm) and the lowest concentration was P3 (350287.72 ppm).&lt;/p&gt;&lt;p class="MDPI17abstract"&gt;&lt;strong&gt;Conclusions: &lt;/strong&gt;The results of the research concluded that the addition of mimosa powder and 3 different levels of myristic acid in a complete feed based on corn stover can increase the nutritional value of a complete feed and reduce the production of methane gas.&lt;/p&gt;

Are locally adapted goats able to recover homeothermy, acid-base and electrolyte equilibrium in a semi-arid region?

The objective of this study was to evaluate the thermoregulatory responses, acid-basic and electrolytic equilibrium of locally adapted goats under natural heat conditions in a semi-arid region. Ten (10) Canindé goats aged between 2 and 3 years, non-lactating, non-pregnant and having a body weight (BW) of 22.90±2.70kg were used in this study. Air temperature (AT) and relative humidity (RH) were measured, and the radiant heat load (RHL) was subsequently calculated. Rectal temperature (RT), respiratory rate (RR), sweating rate (SR) and heat shock (S) were recorded at 1-h intervals for 24 continuous hours. Hydrogen potential (pH), partial pressure of carbon dioxide (PCO2), partial pressure of oxygen (PO2), bicarbonate (HCO3), base excess (BE), total carbon dioxide concentration (TCO2), oxygen saturation (SO2), sodium (Na+) and potassium (K+) were recorded at three moments during the day (5 a.m.; 1 p.m.; 6 p.m.). There were also significant differences between the means of hours of the day for AT and RH. RR was the thermoregulatory response which most closely followed RHL, with important elevations in the periods between 10 a.m. to noon. It was observed that the goats activated their SR mechanism before RR, more precisely between the hours of 9 a.m. and 1 p.m. The acid-base and electrolytic equilibrium for the goats which showed great association with the first components contributed the most to the total variation of the data. The most important variables in the adaptive profile of these animals in order of importance were: SO2, PO2, RR, RT, SR, HCO3, BE, TCO2 and pH. An association between all variables grouped in each period was observed, where the thermoregulatory responses in the periods of 5 a.m. and 6 p.m. were closer than when compared to 1 p.m., showing a physiological return to the initial state. Therefore, the variation in thermoregulatory responses, acid-base and electrolytic equilibrium indicated that the goats have the ability to recover after a challenging environmental condition.