Decrease In PCO2 Research Articles

Acetazolamide Therapy for Metabolic Alkalosis in Pediatric Intensive Care Patients.

Patients in PICUs frequently present hypochloremic metabolic alkalosis secondary to loop diuretic treatment, especially those undergoing cardiac surgery. This study evaluates the effectiveness of acetazolamide therapy for metabolic alkalosis in PICU patients. Retrospective, observational study. A tertiary care children's hospital PICU. Children receiving at least a 2-day course of enteral acetazolamide. None. Demographic variables, diuretic treatment and doses of acetazolamide, urine output, serum electrolytes, urea and creatinine, acid-base excess, pH, and use of mechanical ventilation during treatment were collected. Patients were studied according to their pathology (postoperative cardiac surgery, decompensated heart failure, or respiratory disease). A total of 78 episodes in 58 patients were identified: 48 were carried out in cardiac postoperative patients, 22 in decompensated heart failure, and eight in respiratory patients. All patients received loop diuretics. A decrease in pH and PCO2 in the first 72 hours, a decrease in serum HCO3 (mean, 4.65 ± 4.83; p < 0.001), and an increase in anion gap values were observed. Urine output increased in cardiac postoperative patients (4.5 ± 2.2 vs 5.1 ± 2.0; p = 0.020), whereas diuretic treatment was reduced in cardiac patients. There was no significant difference in serum electrolytes, blood urea, creatinine, nor chloride after the administration of acetazolamide from baseline. Acetazolamide treatment was well tolerated in all patients. Acetazolamide decreases serum HCO3 and PCO2 in PICU cardiac patients with metabolic alkalosis secondary to diuretic therapy. Cardiac postoperative patients present a significant increase in urine output after acetazolamide treatment.

Effect of Marcha Exercise on Serum Electrolytes and Acid–Base Balance in Mangalarga Marchador Horses

The marcha competition is a functional evaluation, without similar in the world. In this competition, the animals perform marcha at average speed between 9 and 12 km/hr for 50 minutes, covering roughly 6 to 7 km with no rest. The aim of this study was to evaluate and compare the effect of batida gait competition on acid–base balance in Mangalarga Marchador horses during an official marcha competition. The study was conducted on 24 Mangalarga Marchador horses, 12 stallions, and 12 mares (aged 4–6 years and 399 ± 45 kg of body weight). Venous blood samples were collected before and after competition. Blood samples were analyzed for acid–base balance, as well as biochemical and electrolyte parameters. In stallions, a significant (P < .05) postexercise increase in pH, partial pressure of oxygen, bicarbonate concentration, base excess, and glucose was noted. Decrease (P < .05) in pCO2 (partial pressure of carbon dioxide), chloride and ionized calcium were observed after exercise only in stallions. No changes (P > .05) in hematocrit, hemoglobin, sodium, and potassium were observed after exercise in all animals. The changes in the acid–base balance and electrolyte profile of the Mangalarga Marchador stallions after marcha competition resulted in hypochloremic metabolic alkalosis. Marcha competition did not cause acid–base disturbance in mares. This study enables an evaluation and comparison of physical effort caused by the marcha exercise on acid–base balance in Mangalarga Marchador horses and provides further evidence of the existence of gender differences in sports horses.

Significant changes in water pCO2 caused by turbulence from waterfalls

Inland waters are sites of intense carbon processing, stocking and transport. We examined the influence of waterfall-turbulence on CO 2 partial pressures (pCO 2 ) before and after waterfalls in a tropical river. The results indicated a 51.4% decrease of pCO 2 from up (1375 ± 320 ppm) to downriver (655 ± 58 ppm), suggesting an unaccounted degassing promoted by waterfall-turbulence. This process needs to be better understood in order to more accurately determine the role of freshwater environments in the global carbon balance.

Comparing High-Frequency Ventilation and Conventional Ventilation on Morphology of Brain, Kidney and Liver in Preterm Babies with Respiratory Distress

Background: The increase in the ventilator rates by conventional mechanical ventilation (CMV) is limited by a minimum amount of time needed for a complete inspiration and expiration. In preterm babies with respiratory distress syndrome, it may not be sufficient to manage the hypercapnia and hypoxia associated. High-frequency ventilation (HFV) can be considered as a substitute for CMV in premature infants by increasing the ventilator rate further and reducing the tidal volume. The current study evaluates the efficacy and effects on brain, liver and kidney morphology of HFV in preterm babies with respiratory distress. Methods: This prospective and analytical study was conducted from December 2011 to January 2013 on 83 preterm babies’ with an initial provisional diagnosis of respiratory distress that needed respiratory support at birth or soon after admission. Initial and follow up blood gas (BG) and cranial U/S, and renal and hepatic function tests were done. Results: The study was conducted on 83 preterm babies, aged less than 37 weeks of gestation, who were divided into control (40) and study (43) groups. The study group showed significantly higher PEEP and PIP values than control in CMV and were shifted to HFV thereafter. The control group needed only CMV. After the intervention, statistically significant improvement in arterial blood gas parameters with respect to blood pH, pCO2 and pO2. The mean blood pH was found to be 7.386 ±0.039, with increase in mean pO2 (before shift =45.44±4.36 vs. after shift=40.56 ±2.597 mm Hg respectively, p= 0.01) and decrease in mean pCO2 (before shift= 38.23±0.03 vs. after shift=42.87 ± 6.915 mm Hg respectively, p=0.01). We can say that HFV helped to reduce acidosis, hypoxia, and hypercapnia in the neonates in the study group. In terms of renal functions, the serum sodium content marginally increased with HFV (After shift= 136.00±3.910 vs. before shift=135.00±5.686 mol/l, p=0.000), Significant increase in mean 24-hour urinary creatinine from their initial CMV values after subjecting them to HFV (before shift 14.509± 4.874 mg/dl vs after shift 15.340±7.054 mg/dl, p=0.002). In terms of hepatic functions, significant difference was observed after intervention was detected with higher PT in HFV group (0.01); on the other hand, no significant difference regarding ALT, PTT and fibrinogen between study and control groups was detected after HFV intervention. Brain ultra-sound scan (BUSS) results showed that the intraventricular haemorrhage (IVH) was reduced in the HFV group as compared to the CMV group. BUSS outcome also showed that there is a significant correlation between IVH and surfactant medication. Conclusion: Rescue HFV improved oxygenation, ventilation, lung recruitment and better oxygenation indices and there was no increased incidence of IVH. In addition, HFV had no deleterious effect on other organs such as the brain, kidney and liver.

High Frequency Jet Ventilation in Respiratory Failure Secondary to Respiratory Syncytial Virus Infection: A Case Series.

To describe the utility of high frequency jet ventilation (HFJV) as a rescue therapy in patients with respiratory failure secondary to respiratory syncytial virus (RSV) that was refractory to conventional mechanical ventilation (CMV). Descriptive study by retrospective review. Pediatric intensive care unit at a tertiary care children's hospital. Infants on mechanical ventilation for respiratory failure due to RSV. Use of HFJV. Eleven patients were placed on HFJV. There was sustained improvement in ventilation on HFJV with a mean decrease in PCO2 of 9 mmHg at 24 h and 11 mmHg at 72 h. There were no significant changes in oxygenation by oxygenation index. No patients required extracorporeal support or suffered pneumothorax, pneumomediastinum, or subcutaneous emphysema. Ten out of 11 (91%) patients survived to discharge from the hospital. High frequency jet ventilation may represent an alternative therapy for RSV-induced respiratory failure that is refractory to CMV.

Autumn CO2 chemistry in the Japan Sea and the impact of discharges from the Changjiang River

AbstractWe made comprehensive surface water CO2 chemistry observations in the Japan Sea during each autumn from 2010 to 2014. The partial pressure of CO2 (pCO2) in surface water, 312–329 μatm, was 10–30 μatm lower in the Japan Sea than in the same latitude range of the western North Pacific adjacent to Japan. According to the sensitivity analysis of pCO2, the lower pCO2 in the Japan Sea was primarily attributable to a large seasonal decrease of pCO2 associated with strong cooling in autumn, particularly in the northern Japan Sea. In contrast, the lower pCO2 in relatively warm, freshwater in the southern Japan Sea was attributable to not only the thermodynamic effect of the temperature changes but also high total alkalinity. This alkalinity had its origin in Changjiang River and was transported by Changjiang diluted water (CDW) which seasonally runs into the Japan Sea from the East China Sea. The input of total alkalinity through CDW also elevated the saturation state of calcium carbonate minerals and mitigated the effects of anthropogenic ocean acidification, at least during autumn. These biogeochemical impacts of CDW in the Japan Sea last until November, although the inflow from the East China Sea to the Japan Sea almost ceases by the end of September. The long duration of the high saturation state of calcium carbonate benefits calcareous marine organisms.

Cenozoic carbon cycle imbalances and a variable weathering feedback

The long-term stability of Earth's climate and the recovery of the ocean–atmosphere system after carbon cycle perturbations are often attributed to a stabilizing negative feedback between silicate weathering and climate. However, evidence for the operation of this feedback over million-year timescales and in response to tectonic and long-term climatic change remains scarce. For example, the past 50 million years of the Cenozoic Era are characterized by long-term cooling and declining atmospheric CO2 (pCO2). During this interval, constant or decreasing carbon fluxes from the solid Earth to the atmosphere suggest that stable or decreasing weathering fluxes are needed to balance the carbon cycle. In contrast, marine isotopic proxies of weathering (i.e., 87Sr/86Sr, δ7Li, and 187Os/188Os) are interpreted to reflect increasing weathering fluxes. Here, we evaluate the existence of a negative feedback by reconstructing the imbalance in the carbon cycle during the Cenozoic using the surface inventories of carbon and alkalinity. Only a sustained 0.25–0.5% increase in silicate weathering is necessary to explain the long-term decline in pCO2 over the Cenozoic. We propose that the long-term decrease in pCO2 is due to an increase in the strength of the silicate weathering feedback (i.e., the constant of proportionality between the silicate weathering flux and climate), rather than an increase in the weathering flux. This increase in the feedback strength, which mirrors the marine isotope proxies, occurs as transient, <1 million year increases in the weathering flux, which remove CO2. As runoff and temperature decline in response, the integrated weathering flux over >1 million year timescales remains invariant to match the long-term inputs of carbon. Over the Cenozoic, this results in stable long-term weathering fluxes even as pCO2 decreases. We attribute increasing feedback strength to a change in the type and reactivity of rock in the weathering zone, which collectively has increased the reactivity of the surface of the Earth. Increasing feedback strength through the Cenozoic reconciles mass balance in the carbon cycle with the marine isotopic proxies of weathering and may explain why there are periods when the Earth system is more sensitive to carbon cycle perturbations.

Dynamic biogeochemical controls on river pCO2 and recent changes under aggravating river impoundment: An example of the subtropical Yangtze River

AbstractThis paper highlights two aspects of the dynamic biogeochemical controls of riverine pCO2 in an increasingly impounded large subtropical river (the Yangtze): the terrestrial dominance through internal respiration of land‐derived organic carbon and the influence of increased autotrophic activity in impounded areas on river pCO2. River pCO2 and total organic carbon (TOC) increase downstream on the main stem (pCO2: 528–1703 µatm; TOC: 137–263 µmol/L) and vary significantly among tributaries (464–3300 µatm; TOC: 109–340 µmol/L). pCO2 displays larger spatial variability than temporal variability and is spatially correlated with river organic carbon across the river (p &lt; 0.05–0.0001, seasonally independent). pCO2 is also negatively correlated with dissolved oxygen (r2 = 0.46, p &lt; 0.0001). Respiration of allochthonous organic carbon in water column is concluded as an essential source of CO2 supersaturation and river heterotrophy. However, significant benthic respiration and/or direct soil CO2 transport (e.g., via groundwater, ~80%) exist at the same time. The temporal and spatial distribution of POC compositional characteristics and chlorophyll a indicate the dominant control of terrestrial processes (e.g., organic matter transport and soil erosion) on the river pCO2 biogeochemistry, especially in warm seasons. Increased autotrophy and significant pCO2 decrease (&gt;60%) do occur in impounded areas (especially in nutrient‐rich rivers), but the decrease is mostly temporal and regional (~8% of the data points are significantly influenced, all from the upper reach and/or major tributaries). The paper concludes that terrestrial influence still dominates the pCO2 biogeochemistry in this increasingly intercepted and regulated river system.

Dynamics of sea-ice biogeochemistry in the coastal Antarctica during transition from summer to winter

The seasonality of carbon dioxide partial pressure (pCO2), air-sea CO2 fluxes and associated environmental parameters were investigated in the Antarctic coastal waters. The in-situ survey was carried out from the austral summer till the onset of winter (January 2012, February 2010 and March 2009) in the Enderby Basin. Rapid decrease in pCO2 was evident under the sea-ice cover in January, when both water column and sea-ice algal activity resulted in the removal of nutrients and dissolved inorganic carbon (DIC) and increase in pH. The major highlight of this study is the shift in the dominant biogeochemical factors from summer to early winter. Nutrient limitation (low Si/N), sea-ice cover, low photosynthetically active radiation (PAR), deep mixed layer and high upwelling velocity contributed towards higher pCO2 during March (early winter). CO2 fluxes suggest that the Enderby Basin acts as a strong CO2 sink during January (−81 mmol m−2 d−1), however it acts as a weak sink of CO2 with −2.4 and −1.7 mmol m−2 d−1 during February and March, respectively. The present work, concludes that sea ice plays a dual role towards climate change, by decreasing sea surface pCO2 in summer and enhancing in early winter. Our observations emphasize the need to address seasonal sea-ice driven CO2 flux dynamics in assessing Antarctic contributions to the global oceanic CO2 budget.

Equilibrium partial pressure of CO2 in Callovian–Oxfordian argillite as a function of relative humidity: Experiments and modelling

Having previously demonstrated that the mineral assemblage of claystone can impose its pCO2 under saturated conditions, we here study the effect of rock desaturation, i.e. the evaporation of pore water, on the partial pressure of CO2 (pCO2) in Callovian–Oxfordian argillite from the Paris Basin (France). In this new study, which combines experiments at room temperature and geochemical modelling, we examine the primary role of capillary forces on chemical equilibria for relative humidity values ranging between 50% and 100%. In particular we are able, without any fitting parameters, to model the experimental decrease of pCO2 as a function of decreasing water content in the argillite. This application to a complex natural system not only confirms the theoretical concepts of geochemistry in capillary contexts, but is promising with respect to other systems, both natural (soil, rock) and industrial (ceramics, granular material).

Quantitative trait loci identified for blood chemistry components of an advanced intercross line of chickens under heat stress.

BackgroundHeat stress in poultry results in considerable economic losses and is a concern for both animal health and welfare. Physiological changes occur during periods of heat stress, including changes in blood chemistry components. A highly advanced intercross line, created from a broiler (heat susceptible) by Fayoumi (heat resistant) cross, was exposed to daily heat cycles for seven days starting at 22 days of age. Blood components measured pre-heat treatment and on the seventh day of heat treatment included pH, pCO2, pO2, base excess, HCO3, TCO2, K, Na, ionized Ca, hematocrit, hemoglobin, sO2, and glucose. A genome-wide association study (GWAS) for these traits and their calculated changes was conducted to identify quantitative trait loci (QTL) using a 600 K SNP panel.ResultsThere were significant increases in pH, base excess, HCO3, TCO2, ionized Ca, hematocrit, hemoglobin, and sO2, and significant decreases in pCO2 and glucose after 7 days of heat treatment. Heritabilities ranged from 0.01-0.21 for pre-heat measurements, 0.01-0.23 for measurements taken during heat, and 0.00-0.10 for the calculated change due to heat treatment. All blood components were highly correlated within measurement days, but not correlated between measurement days. The GWAS revealed 61 QTL for all traits, located on GGA (Gallus gallus chromosome) 1, 3, 6, 9, 10, 12–14, 17, 18, 21–28, and Z. A functional analysis of the genes in these QTL regions identified the Angiopoietin pathway as significant. The QTL that co-localized for three or more traits were on GGA10, 22, 26, 28, and Z and revealed candidate genes for birds’ response to heat stress.ConclusionsThe results of this study contribute to our knowledge of levels and heritabilities of several blood components of chickens under thermoneutral and heat stress conditions. Most components responded to heat treatment. Mapped QTL may serve as markers for genomic selection to enhance heat tolerance in poultry. The Angiopoietin pathway is likely involved in the response to heat stress in chickens. Several candidate genes were identified, giving additional insight into potential mechanisms of physiologic response to high ambient temperatures.Electronic supplementary materialThe online version of this article (doi:10.1186/s12864-016-2601-x) contains supplementary material, which is available to authorized users.

Fossil plant stomata indicate decreasing atmospheric CO&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt; prior to the Eocene–Oligocene boundary

Abstract. A unique stratigraphic sequence of fossil leaves of Eotrigonobalanus furcinervis (extinct trees of the beech family, Fagaceae) from central Germany has been used to derive an atmospheric pCO2 record with multiple data points spanning the late middle to late Eocene, two sampling levels which may be earliest Oligocene, and two samples from later in the Oligocene. Using the inverse relationship between the density of stomata and pCO2, we show that pCO2 decreased continuously from the late middle to late Eocene, reaching a relatively stable low value before the end of the Eocene. Based on the subsequent records, pCO2 in parts of the Oligocene was similar to latest Eocene values. These results suggest that a decrease in pCO2 preceded the large shift in marine oxygen isotope records that characterizes the Eocene–Oligocene transition and that when a certain threshold of pCO2 change was crossed, the cumulative effects of this and other factors resulted in rapid temperature decline, ice build up on Antarctica and hence a change of climate mode.

The use of stable carbon isotope trends as a correlation tool: an example from the Surat Basin, Australia

The Surat Basin’s Middle Jurassic Walloon Subgroup is a productive coal seam gas source in Queensland, Australia. The Walloon Subgroup can be subdivided into the Upper and Lower Juandah coal measures, the Tangalooma Sandstone, the Taroom Coal Measures, and the Eurombah/Durabilla Formation, from top to bottom. Correlation across the basin is challenging due to high lateral variability and lack of extensive stratigraphic markers. The Walloon Subgroup is also, in places, incised by the overlying Springbok Sandstone, sometimes interpreted as far down as the Tangalooma Sandstone. New age dates suggest that the Walloon Coal Measures are Oxfordian in age and mark a period of high rates of Corg production and burial, and an intermittent decrease of atmospheric pCO2. The un- or dis-conformable base of the Springbok Sandstone coincides with a turning point of this supposedly global phenomenon. This study uses organic stable carbon isotope trends as a correlation tool within the Surat Basin’s Walloon Subgroup and its overlying Springbok Sandstone. Analysis of a stratigraphic suite of coal samples from several wells across the Surat Basin shows a gradual enrichment in 13C up section from the Taroom to the Lower Juandah Coal Measures, with the most positive δ13C values within the Upper Juandah Coal Measures. Thereafter there is a rapid reversal to more negative δ13C values for coal samples of the Springbok Sandstone. The upward enrichment occurs well before the shift in maceral composition to increased inertinite content in the coals, suggesting more global allogenic processes are controlling the carbon isotopic trend. The consistency of these trends lends a more confident correlation for sub-units within the Walloon Subgroup, and assists in determining the level of incision disconformity of the Springbok Sandstone.

Rapid increase of observed DIC and pCO2 in the surface waters of the North Sea in the 2001-2011 decade ascribed to climate change superimposed by biological processes

The CO2 system in the North Sea over the 2001-2011 decade was investigated using four comprehensive basin-wide datasets covering the late summer periods of 2001, 2005, 2008 and 2011. We find that rises in surface water DIC and pCO2 exceeded concurrent rises in atmospheric pCO2, which we attribute primarily to biological activity in late summer. After accounting for this biological signal, the observed ocean acidification occurs at a rate that is consistent with concurrent atmospheric and open ocean CO2 increases over the 2001-2011 decade. Nevertheless, we do find a consistent reduction in CO2 undersaturation in the NNS and an increase in CO2 supersaturation in the SNS. We propose that the synergistic effects of increasing atmospheric pCO2 and subsequent decrease in seawater buffering capacity, together with rising sea surface temperatures in the future oceans, may reduce the strength of the North Sea as a CO2 sink. Such a reduction would diminish the efficiency of this region as a continental shelf pump with respect to uptake of CO2 by the sea. Ultimately this would constitute a positive feedback mechanism, i.e. enhancing the airborne fraction of anthropogenic CO2 and thus the net rate of increase of atmospheric pCO2 and subsequent global climate change.

Oceanic pCO2 in the Indian sector of the Southern Ocean during the austral summer–winter transition phase

Biogeochemical processes in the Southern Ocean (SO) play a significant role in regulating the global climate. The physical and biological processes controlling pCO2 in the surface mixed layer at the Indian sector of SO were observed, and changes during the transition period from summer to early winter (January, February and March) were compared. An existing, one-dimensional model describing the mixed-layer carbon cycle was used to determine the relative contributions of biological activity, mixing, thermal and air–sea fluxes on pCO2. A breakdown of the controls shows that the pCO2 distributions are dominated by biological processes during January and February, whereas mixing and thermal effects contributed equally during March. Biological processes accounting for pCO2 decrease reached a maximum value of 108µatm during January. Our results are categorized according to distinct hydrographic regions such as oceanic fronts Sub-tropical front (STF), Sub-Antarctic front (SAF), Polar front (PF) and Antarctic zone (AZ). pCO2 varied among these three studied months, the mean pCO2 increasing from 286µatm in January to 337µatm in March, whereas an opposite trend was observed with dissolved oxygen (O2). The satellite-derived Primary Production (PP) decreased from January to March and also from the STF towards the SAF, PF and AZ. The observed differences in PP and pCO2 during the three months showed the total diatom count ranging from 0.49×103cells/l in March to 3.2×103cells/l in January. Our study indicates that the drawdown in sea-surface pCO2 from March to January could be attributed to the light availability, shallow Mixed layer depth (MLD), high PP, nutrient availability, and low upwelling velocity. Eddies play an important role in regulating pCO2 that require further studies to quantify their percentage contribution in pCO2 rise/drawdown.

An inland sea high nitrate‐low chlorophyll (HNLC) region with naturally high pCO2

AbstractWe present a time series of data for temperature, salinity, nitrate, and carbonate chemistry from September 2011 to July 2013 at the University of Washington's Friday Harbor Laboratories. Samples were collected at the Friday Harbor dock and pump house. Seawater conditions at Friday Harbor were high nitrate‐low chlorophyll, with average nitrate and pCO2 concentrations of ∼ 25 ± 5 μmol L−1 and ∼ 700 ± 103 μatm (pH 7.80 ± 0.06). Transient decreases in surface water nitrate and pCO2 corresponded with the timing of a spring bloom (April through June). The high nitrate and pCO2 originate from the high values for these parameters in the source waters to the Salish Sea from the California Undercurrent (CU). These properties are due to natural aerobic respiration in the region where the CU originates, which is the oxygen minimum zone in the eastern tropical North Pacific. Alkalinity varies little so the increase in pCO2 is due to inputs of dissolved inorganic carbon (DIC). This increase in DIC can come from both natural aerobic respiration within the ocean and input of anthropogenic CO2 from the atmosphere when the water was last at the sea surface. We calculated that the anthropogenic “ocean acidification” contribution to DIC in the source waters of the CU was 36 μmol L−1. This contribution ranged from 13% to 22% of the total increase in DIC, depending on which stoichiometry was used for C/O2 ratio (Redfield vs. Hedges). The remaining increase in DIC was due to natural aerobic respiration.

Two treatment protocols for induction of preterm parturition in ewes—Evaluation of the effects on lung maturation and lamb survival

Lambs born prematurely are often unable to breathe due to pulmonary immaturity and a lack of surfactant production. Attempts to deliver live, moderately preterm lambs from critically ill ewes in late pregnancy are therefore often unsuccessful. The objective of this study was to evaluate the potential benefits of repeated administration of dexamethasone (DEXA) to final-stage pregnant ewes on subsequent perinatal lamb survival and respiratory and metabolic disorders associated with neonatal asphyxia. Two different treatment protocols with dexamethasone were used to induce parturition on days 137 and 138 of pregnancy (full term 149 days).In group LTP (long-term protocol, n=12) low doses of dexamethasone were administered repeatedly starting with 2mg once daily on days 130–133, followed by a single dose of 4mg on day 134. For the final induction of parturition 16mg of the drug were administered on day 135 and this dose was then repeated every 12h until lambing. In group STP (short-term protocol) 15 ewes received 16mg DEXA on day 135, followed by the same dose every 12h until lambing. The vitality and laboratory parameters of the lambs born to these dams were compared to lambs delivered by caesarean section (group CS) on day 147 or 148 of gestation whose dams (n=23) had received a single injection of 10mg dexamethasone 12h prior to surgery, and to lambs born naturally to 19 ewes at full term (group FT) after an average of 149 days of gestation.Lambs from groups LTP and STP were born between day 137 and 139 of gestation, showing characteristics of immaturity. Of 18 lambs in group LTP, 16 survived without critical care (88.9%; 95% confidence interval (CI)=67.2–96.9%). Group STP comprised 24 lambs, 18 of which survived without critical care (75%; 95% CI=55.1–88.0%). Out of 39 lambs in group CS, 37 survived (94.9%; 95% confidence interval (CI)=83.1–98.6%), and 27 of the 28 lambs in group FT, respectively (96.4%; 95% CI=82.3–99.4%). There was no statistically significant difference in the survival rates between the four groups. In all four groups there was a significant increase of pH, BE and HCO3− values within the first 24h post natum, and a significant decrease in pCO2(v) values.Compared to previous studies which indicated high mortality rates in moderately preterm lambs the results indicate that repeated exogenous administration of DEXA has a positive effect on the survival rates of lambs born after induced parturition at around 92% of the full pregnancy term.

CO&lt;sub&gt;2&lt;/sub&gt; 환경에서의 넙치(Paralichthys olivaceus) 심기능의 경시적 변화

Cardiorespiratory variables were measured in flounder Paralicthys olivaceus exposed to acidified seawater equilibrated with a gas mixture containing 5% CO2 gas for 72 h at 20°C. It was found that CO2 produced a significant increase in arterial PCO2 (PaCO2) and significant decreases in arterial pH (pHa). CO2 transiently increased heart rate within 30 min of exposure. After cardiac output was elevated by the increase in heart rate within 30 min, was then reduced by the decrease in both stroke volume and heart rate. The heart responses of flounder differ from those of yellowtail to high CO2 environment.

A 30 Myr record of Late Triassic atmosphericpCO2variation reflects a fundamental control of the carbon cycle by changes in continental weathering

We generate a detailed ~30 Myr record of pCO2 spanning most of the Late Triassic (Carnian-Norian-Rhaetian) to earliest Jurassic (Hettangian), based on stable carbon isotope ratios of soil carbonate and preserved organic matter from paleosols in the eastern North American Newark rift basin. Atmospheric pCO2 was near 4500 ppm in the late Carnian, decreasing to below ~2000 ppm by the late Rhaetian just before the earliest Jurassic eruption of the Central Atlantic Magmatic Province, which triggered measurable pulses of CO2 outgassing. These data are consistent with published modeling results using the GEOCLIM model, which predict a decrease in pCO2 over the Late Triassic as a result of the progressive increase in continental area subject to the intense weathering regime of the tropical humid belt due to Pangea’s northward motion. The fi ner-scale pCO2 changes we observe may be dependent on the lithology introduced to the tropics, such as the dip to ~2000 ppm around 212 Ma and its rebound to ~4000 ppm at 209 Ma, which can be accomplished by introducing a more weatherable subaerial basaltic terrain. These observations indicate that the consumption of CO2 by continental silicate weathering can force long-term changes in pCO2 comparable to those driven by presumed changes in mantle degassing.

Electrolyte shifts across the artificial lung in patients on extracorporeal membrane oxygenation: Interdependence between partial pressure of carbon dioxide and strong ion difference

PurposePartial pressure of carbon dioxide (Pco2), strong ion difference (SID), and total amount of weak acids independently regulate pH. When blood passes through an extracorporeal membrane lung, Pco2 decreases. Furthermore, changes in electrolytes, potentially affecting SID, were reported. We analyzed these phenomena according to Stewart's approach. MethodsCouples of measurements of blood entering (venous) and leaving (arterial) the extracorporeal membrane lung were analyzed in 20 patients. Changes in SID, Pco2, and pH were computed and pH variations in the absence of measured SID variations calculated. ResultsPassing from venous to arterial blood, Pco2 was reduced (46.5 ± 7.7 vs 34.8 ± 7.4 mm Hg, P < .001), and hemoglobin saturation increased (78 ± 8 vs 100% ± 2%, P < .001). Chloride increased, and sodium decreased causing a reduction in SID (38.7 ± 5.0 vs 36.4 ± 5.1 mEq/L, P < .001). Analysis of quartiles of ∆Pco2 revealed progressive increases in chloride (P < .001), reductions in sodium (P < .001), and decreases in SID (P < .001), at constant hemoglobin saturation variation (P = .12). Actual pH variation was lower than pH variations in the absence of measured SID variations (0.09 ± 0.03 vs 0.12 ± 0.04, P < .001). ConclusionsWhen Pco2 is reduced and oxygen added, several changes in electrolytes occur. These changes cause a Pco2-dependent SID reduction that, by acidifying plasma, limits pH correction caused by carbon dioxide removal. In this particular setting, Pco2 and SID are interdependent.