Analysis of the Carbon Dioxide Inhibition by Means of Dissolved Carbon Dioxide Controlled Culture

The concentration of dissolved carbon dioxide in the liquid phase was in proportion to the partial pressure of carbon dioxide in the gas phase, and that of bicarbonate ions was in proportion to the dissolved carbon dioxide tension and pH of the liquid. Although the partial pressure of carbon dioxide was maintained at the same level, the bicarbonate ion concentration varied depending upon the difference in pH values. Thus, the influence of the carbon dioxide tension and bicarbonate ion concentration on the product formation was investigated independently by a dissolved carbon dioxide controlled culture at a constant pH level. The production of inosine was highly affected by the partial pressure of carbon dioxide. The yield of inosine, however, was shown to be independent of the bicarbonate ion concentration in the culturing liquid.

Continuous determination of the cerebrovascular changes induced by bicuculline and kainic acid in unanaesthetized spontaneously breathing rats

Blood flow compensates oxygen demand in the vulnerable ca3 region of the hippocampus during kainate-induced seizures

To explore the mechanism that continuous blood purification (CBP) improve the lung mechanical ventilation parameters, cytokine levels and blood gas analysis results in severe asthma patients, and compare the differences in those parameters between bicarbonate and lactate displacement liquid. According to the random number table, 26 severe asthma patients were allocated into control group (n=10), bicarbonate group (n=8) and lactate group (n=8). Twenty-four hours treatment with mechanical ventilation (control group), mechanical ventilation + CBP (bicarbonate group) or mechanical ventilation + CBP (lactate group) were conducted respectively. Lung mechanical ventilation parameters, serum cytokine level and blood gas analysis results, arterial blood lactate, and electrolytes level were compared among groups. After 24-hour CBP, the lung mechanical ventilation parameters were improved, cytokine levels were decreased, and pH value and partial pressure of oxygen were improved in bicarbonate group and lactate group. The two kinds of displacement liquid had no influence in arterial partial pressure of oxygen (PaO(2)), arterial blood lactate, and serum electrolytes level. The pH value in lactate group was higher than that in bicarbonate group (7.39±0.05 vs. 7.30±0.01, P<0.01). The arterial partial pressure of carbon dioxide (PaCO(2)) was lower in lactate group than that in bicarbonate group (57.14±5.04 mm Hg vs. 89.00±3.66 mm Hg, P<0.01). Combine CBP might improve the lung mechanical ventilation parameter, cytokine level and blood gas analysis more quickly in severe asthma treatment. The lactate displacement liquid improves the retention of carbon dioxide more.

Pathological changes in bone have been related to a preceding impediment of the arterial or venous bone circulation and hypoxia. In this study, we analyzed the feasibility of mass spectrometry in measuring intraosseous oxygen and carbon dioxide. The partial pressures were also measured in intraosseous blood samples, and blood flow in bone was measured with the radioactive microspheres technique. The average partial pressure of oxygen in the lateral femoral condyle was 34 +/- 1.6 mm Hg when measured in intraosseous blood samples and 36.3 +/- 2.3 mm Hg when measured with the on-line mass spectrometer, with significant correlation between the methods. The absolute value of the partial pressure of carbon dioxide measured in situ with mass spectrometry was correlated with the value in the withdrawn blood. There was no significant difference in partial pressures of oxygen and carbon dioxide between the two sides or between repetitive measurements. Arterial occlusion resulted in severe hypoxia, whereas more moderate changes followed venous occlusion.

Arterial blood gases, oxygen, carbon dioxide, and the potential of hydrogen are the key indicators of respiratory status and should be continuously monitored for patients whose respiratory vital signs may alter frequently and rapidly. The arterial partial pressure of oxygen and carbon dioxide can be estimated with transcutaneous monitoring, which measures the partial pressure of oxygen and carbon dioxide diffusing from the skin. However, requiring a heating element and a large, expensive bedside monitor are the limitations of the traditional transcutaneous blood gas monitors preventing continuous monitoring outside a clinical setting. Therefore, we propose a miniaturized fluorescent thin film-based prototype, envisioned as a first-of-its-kind continuous transcutaneous carbon dioxide monitoring wearable device. The computation principle relies on measuring the fluorescence intensity of a carbon dioxide-sensitive thin film. The prototype monitor estimates the partial pressure of carbon dioxide ranging from 0 to 75 mmHg, covering the clinically significant range, 35–45 mmHg for healthy humans. The prototype is designed with a small form factor on a 60 mm×55 mm printed circuit board and consumes 64.33 mW, suitable to be translated into a wearable device in further design stages.

Xylazine, midazolam and a midazolam/ketamine combination were administered to 6 goats in a randomised 3-way block design. All goats received all treatments with at least a 7-day interval between treatments. Statistically significant (P < 0.05) changes were observed in some of the measured cardiopulmonary variables for xylazine and midazolam/ ketamine. Xylazine administration resulted in statistically significant decreases in minute volume, arterial partial pressure of oxygen, heart rate and mean arterial blood pressure. The increase in arterial partial pressure of carbon dioxide was not statistically significant. For the midazolam/ketamine combination, the decrease in tidal volume was statistically significant, but not the decrease in minute volume and increase in arterial partial pressure of carbon dioxide. The decrease in the arterial partial pressure of oxygen was also statistically significant. The mean arterial blood pressure for the combination was statistically significantly higher compared to xylazine. The changes in cardiopulmonary variables after midazolam administration were not statistically significant, such as tidal and minute volume, arterial partial pressure of oxygen and carbon dioxide. However, clinically significant effects such as hypoventilation and hypoxia were observed after its administration. The change in mean arterial blood pressure was minimal.

To investigate the effect of reverse Trendelenburg position versus semi-recumbent position on respiratory parameters of obese critically ill patients. Reverse Trendelenburg position is recommended for obese patients; however, the effect among critically ill patients, especially those on mechanical ventilation, has limited study. Randomised, controlled pretest, repeated post-test trial with two parallel groups. The study started from 13 January 2020-12 March 2020. Adult critically ill patients with a body mass index ≥30 were randomly assigned by computer-generated randomisation to either reverse Trendelenburg position group (intervention) or semi-recumbent position group (active comparator control). Outcome measures were ventilation parameters (dynamic compliance, partial pressure of arterial carbon dioxide and minute volume) and oxygenation parameters (hypoxaemic index and partial pressure of arterial oxygen). Measures were assessed immediately before positioning and after positioning in 10 minutes, 20 minutes and 30 minutes. CONSORT checklist was used to report the current study. Four general intensive care units. One hundred and ten patients (55 patients in each group) completed the study. The reverse Trendelenburg position group had a higher improvement than the semi-recumbent position group as estimated by mean differences in their dynamic compliance, minute volume, partial pressure of carbon dioxide, partial pressure of oxygen and hypoxaemic index. Reverse Trendelenburg position improves obese patients' respiratory parameters more than semi-recumbent position. This study directs nurses to use the reverse Trendelenburg position, which is an important position for enhancing the parameters of ventilation and oxygenation of obese mechanically ventilated patients.

High-flow nasal cannula oxygen therapy reduces the arterial partial pressure of carbon dioxide and acute exacerbation but does not increase exercise capacity or decrease hospitalisation or mortality. The study aimed to test the hypothesis that in chronic obstructive pulmonary disease patients, the use of high-flow nasal cannula decreases arterial partial pressure of carbon dioxide and increases the partial pressure of oxygen and 6-min walking distance. PubMed, Embase and the Cochrane library were searched for eligible studies published from database inception to November 2020 (Preferred Reporting Items for Systematic Reviews and Meta-Analyses checklist). The primary outcomes were partial pressure of carbon dioxide and partial pressure of oxygen, and the secondary outcomes were transcutaneous partial pressure of carbon dioxide and 6-min walking distance. Nine studies (680 patients) were included. high-flow nasal cannula did not decrease partial pressure of carbon dioxide compared with the control interventions (mean difference=-0.81, 95% confidence interval: -2.68 to 1.06, p=.395; I2 =42.9%, pheterogeneity =.105). high-flow nasal cannula decreased partial pressure of carbon dioxide compared with long-term oxygen therapy (mean difference=-3.25, 95% confidence interval: -5.65 to -0.85, p=.008; I2 =0%, pheterogeneity =.375); no difference was observed for the control modalities. high-flow nasal cannula resulted in better partial pressure of carbon dioxide compared with control interventions in hypoxemic patients (mean difference=-2.59, 95% confidence interval: -4.82 to -0.35, p=.023; I2 =32.5%, pheterogeneity =.224), but not in other types of patients. high-flow nasal cannula did not increase partial pressure of oxygen compared with the control interventions (mean difference=1.17, 95% confidence interval: -1.50 to 3.83, p=.390; I2 =0%, pheterogeneity =.660). high-flow nasal cannula decreased transcutaneous carbon dioxide tension (transcutaneous partial pressure of carbon dioxide) compared with the control interventions (mean difference=2.37, 95% confidence interval: 0.07-4.68, p=.044; I2 =8.7%, pheterogeneity =.295). high-flow nasal cannula increased 6-min walking distance compared with the control interventions (mean difference=18.22, 95% confidence interval: 0.86-,35.57, p=.040; I2 =0%, pheterogeneity =.918). The sensitivity analyses showed that the results were robust. High-flow nasal cannula did not significantly decrease partial pressure of carbon dioxide or increase partial pressure of oxygen in chronic obstructive pulmonary disease patients, which is different from the previous meta-analysis, but it decreases transcutaneous partial pressure of carbon dioxide and increased 6-min walking distance. This meta-analysis shows that in patients with chronic obstructive pulmonary disease, high-flow nasal cannula improves both transcutaneous partial pressure of carbon dioxide and 6-min walking distance, suggesting the high-flow nasal cannula has benefits in the management of chronic obstructive pulmonary disease. Considering that the literature suggests no impact of high-flow nasal cannula on hospitalisation and mortality, the benefits of high-flow nasal cannula might be limited to the patients who survive the chronic obstructive pulmonary disease events. Still, the global impact of high-flow nasal cannula on the quality of life of patients with chronic obstructive pulmonary disease should be examined.

Objective. To study the impact of compression on velocity of venous and arterial main blood flow of the lower extremity, as well as cutaneous microcirculation in the back part of the foot in healthy individuals and patients with decompensated forms of varicose disease and postthrombophlebitis syndrome. Materials and methods. In the investigation 56 individuals took part and divided into three groups: Group I – 20 healthy persons; Group II – 15 patients with varicose disease in decompensated stage; Group III– 21 patients with decompensated stage of postthrombophlebitis syndrome. In all participants of the investigation the index of ankle–brachial pressure, deep–femoro–popliteal index, the regional perfusion index, transcutaneous partial pressure of oxygen and partial pressure of carbon dioxide, the arterial blood flow velocity in femoral artery and of venous blood flow distally from sapheno–femoral junction were measured before and after application of elastic medical knitwear of various Class of compression or the cuff pressure. Results. In the Class III compression in patients of Group III the transcutaneously registered indices crossing have occurred between partial pressure of oxygen and carbon dioxide, accompanied by domination of the carbon dioxide partial pressure over the oxygen partial pressure while further enhancement of the compression Class. In patients of Group II this tendency was observed while application of Class IV compression only. At the investigation beginning the values of partial pressure of carbon dioxide registered were higher in the Group III patients, than in the patients of Group II (p=0.0001). Conclusion. While application of the Class III compression the velocity of the hip venous blood flow, comparing with its initial values, have lowered at average by 78% in patients of Group II and at average in 7.4 times in the patients of |Group III (p=0.0001). It is affordable in patients, suffering decompensated postthrombophlebitic syndrome, to apply the elastic compression of Classes I–II, while in those, having varicose disease in decompensated stage, – the elastic compression of Classes III and iV as well.

Cardiopulmonary and acid–base effects of desflurane and sevoflurane in spontaneously breathing cats

Effect of graded hemorrhage on renal cortical perfusion in dogs

We developed an acoustic capnometer to estimate the partial pressures of arterial carbon dioxide from expired air in the pulmonary rehabilitation devices for patients with respiratory failure. Because partial pressures of carbon dioxide reduce the velocity of sound propagating through expired air, we developed an acoustic capnometer. The present study proposes a unique method based on the measurement of acoustic velocity in expired air, thus eliminating the use of a specific carbon dioxide sensor. The current method can fabricate the capnometer at an appreciably low cost, enabling the device to be used for various rehabilitation purposes. The acoustic capnometer comprises a cylindrical small sample cavity, an ultrasonic transmitter-receiver system, electronic circuits for velocity determination, and a microprocessor for data processing. To validate the device, 12 patients with pulmonary disease were enrolled, and end-tidal partial pressures of carbon dioxide obtained from the current device were compared to the carbon dioxide tension measured by conventional arterial blood gas analysis. The results show a linear relationship in the region of interest (40–60 torr). Therefore, the proposed device facilitates the estimation arterial carbon dioxide partial pressures without sampling blood.

The effects of acute exposure to 3 different temperature and humidity conditions on arterial blood-gas and acid-base balance in goats were investigated after intravenous bolus administration of xylazine at a dose of 0.1 mg/kg. Significant (P<0.05) changes in the variables occurred under all 3 environmental conditions. Decreases in pH, partial pressure of oxygen and oxyhaemoglobin saturation were observed, and the minimum values for oxygen tension and oxyhaemoglobin saturation were observed within 5 min of xylazine administration. The pH decreased to its minimum values between 5 and 15 min. Thereafter, the variables started to return towards baseline, but did not reach baseline values at the end of the 60 min observation period. Increases in the partial pressure of carbon dioxide, total carbon dioxide content, bicarbonate ion concentration, and the actual base excess were observed. The maximum increase in the carbon dioxide tension occurred within 5 min of xylazine administration. The increase in the actual base excess only became significant after 30 min in all 3 environments, and maximal increases were observed at 60 min. There were no significant differences between the variables in the 3 different environments. It was concluded that intravenous xylazine administration in goats resulted in significant changes in arterial blood-gas and acid-base balance that were associated with hypoxaemia and respiratory acidosis, followed by metabolic alkalosis that continued for the duration of the observation period. Acute exposure to different environmental temperature and humidity conditions after xylazine administration did not influence the changes in arterial blood-gas and acid-base balance.

In inosine fermentation, the yield of the product was closely related to the partial pressure of carbon dioxide in the culture system rather than the bicarbonate ion concentration in the culture liquid. The inhibitory effect of carbon dioxide was restored by the methods of reducing the partial pressure of carbon dioxide lower than a certain level. Both ventilation and chemical absorption were applicable for the restoration of the carbon dioxide inhibition, but ventilation had great advantages over the other method from an industrial view-point. In the estimation of aeration-agitation conditions for the scale-up of submerged fermentation in which carbon dioxide was inhibitory, the rate of aeration was to be established to make sufficient ventilation and overcome this inhibition. A scheme for the procedure for the estimation of aeration-agitation conditions under the consideration of influences of carbon dioxide on submerged fermentation was proposed in this paper.