scholarly journals Usefulness of venous-to-arterial partial pressure of CO2 difference to assess oxygen supply to demand adequacy: effects of dobutamine

2019 ◽  
Vol 11 (S11) ◽  
pp. S1574-S1578 ◽  
Author(s):  
Boulos Nassar ◽  
Jihad Mallat
Keyword(s):  
Partial Pressure ◽  
Oxygen Supply ◽  
Arterial Partial Pressure ◽  
Partial Pressure Of Co2

Effect of arterial PCO2 on 2-[1-14C]deoxy-D-glucose uptake by feline cerebral arteries

1986 ◽  
Vol 61 (4) ◽  
pp. 1288-1292
Author(s):  
D. R. Kostreva ◽  
J. McNeely ◽  
E. J. Zuperku
Keyword(s):  
Partial Pressure ◽  
Glucose Uptake ◽  
Blood Vessels ◽  
Glucose Utilization ◽  
Cerebral Arteries ◽  
Arterial Pco2 ◽  
Arterial Partial Pressure ◽  
Partial Pressure Of Co2 ◽  
Autoradiographic Technique

The effect of high and low arterial CO2 on the glucose utilization of nine major cerebral arteries was studied in cats anesthetized with pentothal using the quantitative 2-[1–14C]deoxy-D-glucose autoradiographic technique. All nine cerebral arteries from animals subjected to an arterial partial pressure of CO2 (PCO2) of 20 Torr utilized significantly more (P less than 0.025) glucose than the group subjected to an arterial PCO2 of 60 Torr. Mean relative glucose utilization of the 20-Torr PCO2 group was 105 +/- 9.5 mumol X 100g-1 X min-1 (+/- SE, n = 18) as compared with 49 +/- 6 mumol X 100g-1 X min-1 (+/- SE, n = 26) for the 60-Torr PCO2 group. This study demonstrates that blood vessels can be studied in vivo using the 2-[1-14C]deoxy-D-glucose autoradiographic technique. It also demonstrates that a physiological stimulus like CO2 can produce measurable changes in glucose utilization of cerebral arteries in vivo.

Interaction of chemoreceptor effects and its dependence on the intensity of stimuli

1982 ◽  
Vol 52 (3) ◽  
pp. 602-606 ◽  
Author(s):  
J. M. Adams ◽  
M. L. Severns
Keyword(s):  
Partial Pressure ◽  
Tidal Volume ◽  
Brain Stem ◽  
Breathing Frequency ◽  
Membrane Oxygenator ◽  
Control Value ◽  
Arterial Partial Pressure ◽  
Control Respiration ◽  
Partial Pressure Of Co2 ◽  
Anesthetized Dogs

We have studied the way in which carotid and medullary chemoreceptor effects combine to control respiration in pentobarbital anesthetized dogs. The carotid sinuses were autoperfused from a membrane oxygenator system to produce either normoxic or hypoxic-hypercapnic blood without producing brain stem hypoxia. The dogs breathed CO2 in O2, N2 mixtures regulated to produce isocapnic levels of arterial partial pressure of CO2 (PaCO2) of 36, 54, and 68 Torr at PaO2 = 87. Tidal volume (VT) increased (P less than 0.05) from a control value of 317 ml to 545 at PaCO2 = 54 but did not increase further at PaCO2 = 68. Carotid chemoreceptor stimulation increased VT to 432 ml at PaCO2 = 36 (P less than 0.05) but did not increase VT at the higher levels of PaCO2. Thus, VT has reached a maximum at PaCO2 = 54 Torr and was not increased further by either chemoreceptor drive. Breathing frequency (f) increased (P less than 0.05) from an eupnic value of 20.2 breaths/min to 35.5 and 41.3 at PaCO2 = 54 and 68, respectively. Carotid chemoreceptor stimulation increased (P less than 0.05) f by 7.7, 5.2, and 5.0 breaths/min at each of the levels of PaCO2. Tidal volume exhibited a less-than-additive (P less than 0.05) combination of chemoreceptor effects but f was not significantly different from additive. We conclude that, in pentobarbital-anesthetized dogs, f continues to increase at chemoreceptor drives beyond those at which VT reaches a maximum. This VT nonlinearity may be responsible for the different interactions found in these experiments.

scholarly journals A Simple and Accurate Approach for Determining the VFA Concentration in Anaerobic Digestion Liquors, Relying on Two Titration Points and an External Inorganic Carbon Analysis

2021 ◽  
Vol 5 (2) ◽  
pp. 15
Author(s):  
Paz Nativ ◽  
Yonatan Gräber ◽  
Yaron Aviezer ◽  
Ori Lahav
Keyword(s):  
Partial Pressure ◽  
Volatile Fatty Acids ◽  
Inorganic Carbon ◽  
Strong Acid ◽  
Direct Analysis ◽  
Anaerobic Digesters ◽  
Acid Titration ◽  
Partial Pressure Of Co2 ◽  
Ph Range

A new analytic approach is presented for determining the total volatile fatty acids (VFAT) concentration in anaerobic digesters. The approach relies on external determination of the inorganic carbon concentration (CT) in the analyzed solution, along with two strong-acid titration points. The CT concentration can be determined by either a direct analysis (e.g., by using a TOC device) or by estimating it from the recorded partial pressure of CO2(g) in the biogas (often a routine analysis in anaerobic digesters). The titration is carried out to pH 5.25 and then to pH 4.25. The two titration results are plugged into an alkalinity-mass-based equation and then the two terms are subtracted from each other to yield an equation in which VFAT is the sole unknown (since CT is known and the effect of the total orthophosphate and ammonia concentrations is shown to be small at this pH range). The development of the algorithm and its verification on four anaerobic reactor liquors is presented, on both the raw water and on acetic acid-spiked samples. The results show the method to be both accurate (up to 2.5% of the expected value for VFAT/Alkalinity >0.2) and repetitive when the total orthophosphate and ammonia concentrations are known, and fairly accurate (±5% for VFAT >5 mM) when these are completely neglected. PHREEQC-assisted computation of CT from the knowledge of the partial pressure of CO2(g) in the biogas (and pH, EC and temperature in the liquor) resulted in a very good estimation of the CT value (±3%), indicating that this technique is adequate for the purpose of determining VFAT for alarming operators in case of process deterioration and imminent failure.

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