DO2 Values Research Articles

Relation Between Multiplication of Venous Carbon Dioxide Partial Pressure (PvCO2) and the Ratio of Gas Flow to Pump Flow (Ve/Q) with Hyperlactatemia During Cardiopulmonary Bypass.

The incidence of hyperlactatemia due to hypoperfusion during cardiopulmonary bypass (CPB) increases morbidity. Carbon dioxide production during CPB is one of the lactate production markers, in addition to other markers such as delivery oxygen (DO2), oxygen consumption (VO2), mixed vein oxygen saturation (SvO2), and oxygen extraction ratio (O2ER). This observational analytic study was conducted on 40 adult cardiac surgery patients using a CPB machine. Initial lactate is taken when entering CPB and final lactate is examined 15 min after coming off bypass. The values of DO2, VO2, SvO2, VCO2, respiratory quotient (RQ), DO2/VCO2, PvCO2 × Ve/Q were calculated from the results of blood and venous gas analysis 1 h after entering CPB in the nadir of core temperature and lowest pump flow. The multivariate test showed that the value of PvCO2 × Ve/Q was more effective than other oxygenation and carbon dioxide parameters in predicting an increase in the percentage of lactate. Each increase of 1 mmHg PvCO2 ×× Ve/Q can predict a final lactate increase of 29% from the initial lactate. The high PvCO2 × Ve/Q value is also the strongest correlation factor for the incidence of hyperlactatemia after CPB (final lactate >3 mmol/L). The cutoff value of this marker is >19.3 mmHg, which has a sensitivity of 100% and a specificity of 55.6% with a strong correlation value. The PvCO2 × Ve/Q value proved to be one of the significant markers in predicting hyperlactatemia during cardiac surgery using CPB.

Trial of Oxygen Delivery on Cardiopulmonary Bypass and Major Clinical Outcomes

BackgroundLow oxygen delivery (DO2) on cardiopulmonary bypass has been associated with acute kidney injury. We sought to determine the association of intraoperative DO2, postoperative length of stay, and major postoperative events. MethodsDO2 values were calculated in 845 patients after initiation, and every 30 minutes on bypass. Pump flows were increased for DO2 < 280 mL O2/min/m2, but care was not otherwise adjusted. Patients were retrospectively separated into 3 groups based on DO2 values: Group A, all readings ≥280 mL O2/min/m2; Group B, ≥1 reading <280 mL O2/min/m2; Group C, ≥2 readings <280 mL O2/min/m2. Patient outcomes were analyzed. ResultsWe analyzed 845 consecutive adult cardiac cases. Group B patients had a higher Society of Thoracic Surgeons Predicted Risk of Mortality compared with Group A (1.9% vs 1.2%, P < .001), and this effect was amplified for Group C patients (2.2%, P < .001). Postoperative length of stay was lowest for Group A patients (5.2 days) compared with Group B (6.6 days, P < .001) and Group C (7.0 days, P < .001). Overall complications rates were low, although Group A patients experienced lower rates of prolonged ventilation (3.5%) compared with Group B (6.5%, P = .04) and Group C (9.2%, P = .004). Multivariable regression analysis confirmed that DO2 above threshold was associated with significantly reduced rates of prolonged ventilation and postoperative length of stay. Other outcomes were similar between groups. ConclusionsEven a single DO2 value below threshold was associated with excess prolonged ventilation and postoperative length of stay, but not other outcomes.

High Arterial Lactate Levels after Hepatic Resection Are Associated with Low Oxygen Delivery and Predict Severe Postoperative Complications.

High End-Surgery Arterial Lactate Concentration (ES-ALC) predicts poor outcome after hepatectomy. The aim of this study was to identify intraoperative hemodynamic parameters predicting high ES-ALC during elective liver resection. Patients who underwent liver resection between 2017 and 2018, under FloTrac/EV1000TM hemodynamic monitoring, were included. The ES-ALC cutoff best predicting severe postoperative complications was identified. Association between high ES-ALC and preoperative and intraoperative variables was assessed. 108 patients were included; 90-day mortality was 0.9% and severe morbidity 14.8%. ES-ALC cutoff best discriminating severe complications was 5.05 mmol/L. Patients with ES-ALC > 5.0 mmol/L had a relative risk of severe complications of 2.8% (p = 0.004). High ES-ALC patients had longer surgery and ischemia duration, larger blood losses and higher requirements of fluids and blood transfusions. During surgery, hemoglobin concentration and oxygen delivery (DO2) decreased more significantly in patients with high ES-ALC, although they had similar values of stroke volume and cardiac output to those of other patients. At multivariate analysis, surgery duration and lowest recorded DO2 value were the strongest predictors of high ES-ALC. ES-ALC > 5.0 mmol/L in elective liver resection predicts postoperative morbidity and is essentially driven by the impaired DO2. Timely correction of blood losses might prevent the ES-ALC increase.

Critical oxygen delivery threshold during cardiopulmonary bypass in older cardiac surgery patients with increased frailty risk

Older patients have a higher cardiac surgery-associated acute kidney injury (CSA-AKI) related mortality. Low oxygen delivery (DO2) during cardiopulmonary bypass (CPB) is a risk factor for CSA-AKI, but critical DO2 thresholds for older patients are unknown. This study investigated critical DO2 thresholds for CSA-AKI in patients ≥70 years undergoing on-pump cardiac surgery. Patients were enrolled from July 2015 until August 2017. CPB data from 432 patients were collected, and DO2 values were calculated per minute. The primary outcome was CSA-AKI. The association between DO2 and CSA-AKI was analysed with multivariable regression analysis. Multiple DO2 thresholds were analysed. The association between CSA-AKI and the area below the DO2 thresholds (DO2 deficit) was evaluated, as was the association between frailty and CSA-AKI. CSA-AKI occurred in 63 (14.6%) patients. Mean and nadir (lowest) DO2 values were lower in patients with CSA-AKI (283 vs 312 ml/min/m2; P-value <0.001 and 238 vs 270 ml/min/m2; P-value <0.001, respectively). The adjusted relative risk for CSA-AKI was 1.006 [99% confidence interval (CI) 1.001-1.012] per ml/min/m2 nadir DO2 decrease. The critical DO2 threshold was 270 ml/min/m2 [adjusted relative risk 2.06 (99% CI 1.33-2.80)]. The DO2 deficit below 270 ml/min/m2 was associated with CSA-AKI [adjusted relative risk 2.84 (99% CI 1.87-3.81)]. No association between frailty and CSA-AKI was found (P = 0.82). Low DO2 increased the risk for CSA-AKI in older patients who had cardiac surgery. A critical DO2 threshold of 270 ml/min/m2 was applicable for frail and non-frail patients. The efficacy of a DO2 >270 ml/min/m2 to reduce CSA-AKI in older patients needs further evaluation.

Hypoxia Generated by Avian Embryo Growth Induces the HIF-α Response and Critical Vascularization

Cancer research has transformed our view on cellular mechanisms for oxygen sensing. It has been documented that these mechanisms are important for maintaining animal tissues and life in environments where oxygen (O2) concentrations fluctuate. In adult animals, oxygen sensing is governed by the Hypoxia Inducible Factors (HIFs) that are stabilized at low oxygen concentrations (hypoxia). However, the importance of hypoxia itself during development and for the onset of HIF-driven oxygen sensing remains poorly explored. Cellular responses to hypoxia associates with cell immaturity (stemness) and proper tissue and organ development. During mammalian development, the initial uterine environment is hypoxic. The oxygenation status during avian embryogenesis is more complex since O2 continuously equilibrates across the porous eggshell. Here, we investigate HIF dynamics and use microelectrodes to determine O2 concentrations within the egg and the embryo during the first four days of development. To determine the increased O2 consumption rates, we also obtain the O2 transport coefficient (DO2) of eggshell and associated inner and outer shell membranes, both directly (using microelectrodes in ovo for the first time) and indirectly (using water evaporation at 37.5°C for the first time). Our results demonstrate a distinct hypoxic phase (&amp;lt;5% O2) between day 1 and 2, concurring with the onset of HIF-α expression. This phase of hypoxia is demonstrably necessary for proper vascularization and survival. Our indirectly determined DO2 values are about 30% higher than those determined directly. A comparison with previously reported values indicates that this discrepancy may be real, reflecting that water vapor and O2 may be transported through the eggshell at different rates. Based on our obtained DO2 values, we demonstrate that increased O2 consumption of the growing embryo appears to generate the phase of hypoxia, which is also facilitated by the initially small gas cell and low membrane permeability. We infer that the phase of in ovo hypoxia facilitates correct avian development. These results support the view that hypoxic conditions, in which the animal clade evolved, remain functionally important during animal development. The study highlights that insights from the cancer field pertaining to the cellular capacities by which both somatic and cancer cells register and respond to fluctuations in O2 concentrations can broadly inform our exploration of animal development and success.

Gas–Liquid Mass Transfer around a Rising Bubble: Combined Effect of Rheology and Surfactant

The influence of viscosity and surface tension on oxygen transfer was investigated using planar laser-induced fluorescence with inhibition (PLIF-I). The surface tension and the viscosity were modified using Triton X-100 and polyacrylamide, respectively. Changes in the hydrodynamic parameters of millimetric bubbles were identified, and transfer parameters were calculated. The results revealed a decrease in the mass transferred in the presence of a contaminant. For modified viscosity, the decrease in mass transferred was allowed for by current correlations, but the presence of surfactant led to a sharp decrease in the liquid side mass transfer coefficient, which became even lower when polymer was added. An explanation for the gap between classical correlations and experimental values of kL is discussed, and a hypothesis of the existence of an accumulation of contaminant in the diffusion layer is proposed. This led to the possibility of a decrease in the diffusion coefficient and oxygen saturation concentration in the liquid film, explaining the discrepancy between models and experience. Adapted values of DO2 and [O2] * in this layer were estimated. This original study unravels the complexity of mass transfer from an air bubble in a complex medium.

Redox capacity of rocks and sediments by high temperature chalcometric titration

We present an analytical method to quantify the absolute redox capacity, ΔO2, of geological materials. The protocol consists in a high temperature chalcometric titration by which a known amount of oxygen gas is exchanged between a solid state oxygen donor, CuO, and an oxygen acceptor, the sample, at elevated temperature. Calibration of the method using elemental C, native S and magnetite demonstrates that it effectively oxidizes C, S and Fe to their terminal oxidation state, C4+, S6+ and Fe3+, respectively. Because the metric is independent of processes of internal equilibration within the system, it can be used for quantitative assessments of redox fluxes in open geological systems, in the surface or deep Earth. Preliminary results suggest that the mass specific redox capacity, dO2, of geological materials span many orders of magnitude, ranging from less than 500 μmol O2/g for ultramafic rocks and lower crustal amphibolites, to more than 30000 μmol O2/g for black shales. This highlights a counterintuitive yet fundamental characteristic of our planet. Rocks characterized by elevated dO2 values are ubiquitous in the oxic Earth's surface, while the upper mantle and lower crust are typically composed of rocks with much lower dO2. This work will contribute to provide a more nuanced and complete perspective on the sedimentary and geodynamic processes that have shaped the redox structure of the Earth.

Effect of thermal helium oxygen mixture оn сentral hemodynamics and oxygen transport in patients with acute hypercapnic respiratory failure with chronic obstructive pulmonary disease

The aim of this study is to assessment of the rapid effects of t-He/O2 in comparison with the effective level of high-flow oxygen therapy (HPO) on the main indicators of oxygen transport, central and pulmonary hemodynamics in patients with chronic obstructive pulmonary disease (COPD) with hypercapnic acute respiratory failure.Methods. A total of 33 (29 male, 4 female) patients were included in a randomized, comparative study with exacerbation of COPD and acute respiratory failure, admitted to the department of anesthesiology and intensive care of D.D.Pletnev City Teaching Hospital, Moscow Healthcare Department, between March and May 2017. Patients were divided into two groups: the 1st group – 18 patients (15 male, 3 female) receiving t-He/O2 (He – 70%, O2 – 30% at a temperature of 70 °C; the 2nd group – 15 patients (14 male, 1 female) receiving high-flow oxygen therapy with FiO2 – 30% through a Venturi mask for the treatment of ODN against the background of basic therapy of the underlying disease, according to the recommendations of GOLD 2016. Assessment of oxygen transport, central and pulmonary hemodynamics was carried out through the definition of indicators: saturation of hemoglobin of arterial blood with oxygen (SaO2), saturation of venous blood hemoglobin with oxygen (SvO2), partial pressure of arterial blood oxygen (РaO2), partial pressure of arterial blood carbon dioxide (РaCO2), partial pressure of mixed venous blood oxygen (РvO2), partial pressure of mixed venous blood carbon dioxide (РvCO2),mean pulmonary artery pressure (MPAP), cardiac output (SV), heart index (CI), pulmonary vascular resistance (RVRI), impact volume index (SVI), pulmonary vascular resistance index (RVRI), left ventricular shock index (LVSW), right ventricular shock index (RVSW), system speed of oxygen delivery (DO2), the coeffiCIent of extraction of oxygen (ExO2), shunt fractions (venous mixing) (Qs / Qt)).Results. Short-term inhalation with a thermal helium-oxygen mixture in patients with COPD with hypercapnic acute respiratory failure is accompanied by an increase in SaO2 94,1 (92,8; 97,5) initially 86,1 (85,9; 88,1), РаО2 (78,1 (74,8; 80,1) initially 55,2 (52,5; 65,3)), decline РаСО2 (57,4 (54,2; 66.4) initially 65,4 (58,1; 67,2)). Thermal helium-oxygen mixture leads to stabilization of hemodynamics, improving the work of the right and left heart: decline MPAP 28,2 (24,3; 32,8) initially 43,3 (40,1; 49,5), RVRI (285,3 (258,4; 362,7) initially 592,1 (498,2; 623,5)), RVSW (16,2 (14,1; 21,4) initially 25,8 (21,8; 32)), HR 91,1 (86,4; 98,7) initially 115 ((105; 118) to increase LVSW (58,2 (49,8; 62,4) initially 35,5 (28,9; 42,1)), SVI 36,2 (31,8; 42,1) initially 31,5 (28,4; 36,2). Elimination of arterial hypoxemia and a positive effect on hemodynamics ensures adequate oxygen transport to tissues, which is expressed in the normalization of DO2 values DO2 (980,4 (858,45; 1208) initially 280,3 (270,34; 387,4)) и ExO2 (27,8 (25,6; 34,5) initially 32,1 (30,7; 39,8) and decline Qs/Qt. (28,7 (18,6; 35,4) initially 42,8 (39,2; 49,1).Conclusion. Short-term therapy of patients with COPD with hypercapnic acute respiratory failure using the t-He/O2 method, in comparison with high-flow oxygen therapy, improves blood oxygenation and hemodynamics. Elimination of arterial hypoxemia and a positive effect on hemodynamics made it possible to ensure adequate oxygen transport to tissues, which was expressed in the normalization of transport values, oxygen delivery, and a decrease in the shunt fraction.

Continuous Noninvasive Hemoglobin Monitoring Reflects the Development of Acute Hemodilution After Consecutive Fluid Challenges

Consecutive fluid challenges (FCs) are frequently administered to maximize the stroke volume (SV) as part of a goal-directed therapy (GDT) strategy. However, fluid administration may also cause acute hemodilution that might lead to an actual paradoxical decrease in oxygen delivery (DO2). The aim of this study was to examine whether continuous noninvasive hemoglobin (SpHb) monitoring can be used to detect the development of acute hemodilution after graded fluid administration. In 40 patients who underwent major vascular or gastrointestinal surgery, an FC, consisting of 250 mL colloid solution, was administered. When the SV increased by ≥10%, the FC was repeated up to a maximum of 3 times. Laboratory-measured hemoglobin concentrations (BHb), SpHb, SV, cardiac output (CO), and DO2 values were recorded after each FC. All 40 patients received the first FC, 32 patients received the second FC, and 20 patients received the third FC (total of 750 mL). Out of the 92 administered FCs, only 55 (60%) caused an increase in SV ≥10% ("responders"). The first and the second FCs were associated with a significant increase in the mean CO and DO2, while the mean SpHb and BHb decreased significantly. However, the third and last FC was associated with no statistical difference in CO and SV, a further significant decrease in mean SpHb and BHb, and a significant decrease in DO2 in these patients. Compared to their baseline values (T0), BHb and SpHb decreased by a mean of 5.3% ± 4.9% and 4.4% ± 5.2%, respectively, after the first FC (T1; n = 40), by 9.7% ± 8.4% and 7.9% ± 6.9% after the second FC (T2; n = 32), and by 14.5% ± 6.2% and 14.6% ± 5.7% after the third FC (T3; n = 20). Concordance rates between the changes in SpHb and in BHb after the administration of 250, 500, and 750 mL colloids were 83%, 90%, and 100%, respectively. Fluid loading aimed at increasing the SV and the DO2 as part of GDT strategy is associated with acute significant decreases in both BHb and SpHb concentrations. When the administration of an FC is not followed by a significant increase (≥10%) in the SV, the DO2 decreases significantly due to the development of acute hemodilution. Continuous noninvasive monitoring of SpHb does not reflect accurately absolute BHb values, but may be reliably used to detect the development of acute hemodilution especially after the administration of at least 500 mL of colloids.

Tracking DO2 with Compensatory Reserve During Whole Blood Resuscitation in Baboons.

Hemorrhagic shock can be mitigated by timely and accurate resuscitation designed to restore adequate delivery of oxygen (DO2) by increasing cardiac output (CO). However, standard care of using systolic blood pressure (SBP) as a guide for resuscitation may be ineffective and can potentially be associated with increased morbidity. We have developed a novel vital sign called the compensatory reserve measurement (CRM) generated from analysis of arterial pulse waveform feature changes that has been validated in experimental and clinical models of hemorrhage. We tested the hypothesis that thresholds of DO2 could be accurately defined by CRM, a noninvasive clinical tool, while avoiding over-resuscitation during whole blood resuscitation following a 25% hemorrhage in nonhuman primates. To accomplish this, adult male baboons (n = 12) were exposed to a progressive controlled hemorrhage while sedated that resulted in an average (± SEM) maximal reduction of 508 ± 18 mL of their estimated circulating blood volume of 2,130 ± 60 mL based on body weight. CRM increased from 6 ± 0.01% at the end of hemorrhage to 70 ± 0.02% at the end of resuscitation. By linear regression, CRM values of 6% (end of hemorrhage), 30%, 60%, and 70% (end of resuscitation) corresponded to calculated DO2 values of 5.9 ± 0.34, 7.5 ± 0.87, 9.3 ± 0.76, and 11.6 ± 1.3 mL O2·kg·min during resuscitation. As such, return of CRM to ∼65% during resuscitation required only ∼400 mL to restore SBP to 128 ± 6 mmHg, whereas total blood volume replacement resulted in over-resuscitation as indicated by a SBP of 140 ± 7 mmHg compared with an average baseline value of 125 ± 5 mmHg. Consistent with our hypothesis, thresholds of calculated DO2 were associated with specific CRM values. A target resuscitation CRM value of ∼65% minimized the requirement for whole blood while avoiding over-resuscitation. Furthermore, 0% CRM provided a noninvasive metric for determining critical DO2 at approximately 5.3 mL O2·kg·min.

Systemic Oxygen Delivery during One-Lung Ventilation: Comparison between Propofol and Sevoflurane Anaesthesia in a Randomised Controlled Trial.

Systemic oxygen delivery (DO2) is a more comprehensive marker of patient status than arterial oxygen saturation (SaO2), and DO2 in the range of 330–500 mL min−1 is reportedly adequate during anaesthesia. We measured DO2 during one-lung ventilation (OLV) for thoracic surgery—where the risk of pulmonary shunt is significant, and hypoxia occurs frequently—and compared sevoflurane and propofol, the two most commonly used anaesthetics in terms of DO2. Sevoflurane impairs hypoxic pulmonary vasoconstriction. Thus, our hypothesis was that propofol-based anaesthesia would show a higher DO2 value than sevoflurane-based anaesthesia. This was a double-blinded randomised controlled trial conducted at a university hospital from 2017 to 2018. The study population consisted of patients scheduled for lobectomy under OLV (N = 120). Sevoflurane or propofol was titrated to a bispectral index of 40–50. Haemodynamic variables were measured during two-lung ventilation (TLV) and OLV at 15 and 45 min (OLV15 and OLV45, respectively) using oesophageal Doppler monitoring. The mean DO2 (mL min−1) was not different between the sevoflurane and propofol anaesthesia groups (TLV: 680 vs. 706; OLV15: 685 vs. 703; OLV45: 759 vs. 782, respectively). SaO2 was not correlated with DO2 (r = 0.09, p = 0.100). Patients with SaO2 < 94% showed adequate DO2 (641 ± 203 mL min−1), and patients with high SaO2 (> 97%) showed inadequate DO2 (14% of measurements < 500 mL min−1). In conclusion, DO2 did not significantly differ between sevoflurane and propofol. SaO2 was not correlated with DO2 and was not informative regarding whether the patients were receiving an adequate oxygen supply. DO2 may provide additional information on patient status, which may be especially important when patients show a low SaO2.

Tracking DO2 with Compensatory Reserve during Whole Blood Resuscitation in Baboons

BackgroundHemorrhagic shock can be mitigated by timely and accurate resuscitation designed to restore adequate delivery of oxygen (DO2) by increasing cardiac output (CO). However, standard care of using systolic blood pressure (SBP) as a guide for resuscitation has proven ineffective and can be associated with increased morbidity. We have developed a novel vital sign called the compensatory reserve (CRM) generated from analysis of arterial pulse waveform feature changes that has been validated in experimental and clinical models of hemorrhage. We tested the hypothesis that thresholds of DO2 could be accurately defined by CRM while avoiding over resuscitation during whole blood resuscitation following a 25% hemorrhage in non‐human primates.MethodsTo accomplish this, adult male baboons (n=12) were exposed to a progressive controlled hemorrhage that resulted in an average (± SD) maximal reduction of 601 ± 18 ml of their estimated circulating blood volume of 1,262 ± 64 ml based on body weight. Values of DO2 were calculated as the product of CO times O2 carrying capacity of hemoglobin (i.e., Hb content × 1.34).ResultsAverage (± SD) CRM increased from 6 ± 5 % at the end of hemorrhage to 70 ± 7 % at the end of resuscitation. DO2 of 12.1, 10.3, and 7.0 ml O2·kg−1 ·min−1 were calculated at 0% (baseline), 12.5% and 25% blood loss. By linear regression, CRM values of 6% (decompensation), 35%, and 68% corresponded to calculated DO2 values of 6.0, 9.2, and 12.1 ml O2·kg−1 ·min−1 during resuscitation. As such, return of CRM to baseline during resuscitation with only ~ 450 ml provided adequate DO2 (12.5 ml O2·kg−1 ·min−1) while total blood volume replacement (~600 ml) resulted in over resuscitation as indicated by an average increase in SBP (+17 mmHg) and CO (+0.1 L/min) over baseline values.ConclusionConsistent with our hypothesis, thresholds of DO2 were associated with specific CRM values. A target resuscitation CRM value of 70% minimized the requirement for whole blood, while avoiding over resuscitation. Furthermore, CRM at 0% provided a noninvasive metric for determining critical DO2 at approximately 5.4 ml O2·kg−1 ·min−1.Support or Funding InformationThis research was supported in part by appointment of Ms. Koons to the Postgraduate Research Fellowship Program at the US Army Institute of Surgical Research administered by the Oak Ridge Institute for Science and Education through an interagency agreement between the US Department of Energy and USAMRMC. Study funding was provided by a grant from the US Army Combat Casualty Care Research Program (D‐009‐2014‐USAISR). Linearregression of the relationship between DO2 and compensatory reserve during whole blood resuscitation in baboons. Data are expressed as mean ± SE.imageLinearregression of the relationship between DO2 and compensatory reserve during whole blood resuscitation in baboons. Data are expressed as mean ± SE.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Development of a process control strategy for the serum-free microcarrier expansion of human mesenchymal stem cells towards cost-effective and commercially viable manufacturing

Human Mesenchymal Stem Cells (hMSCs) are advancing through clinical development with the first allogeneic adult hMSC therapy receiving approval in Europe. To enable successful large-scale manufacture of hMSC therapies, increased product consistency and yield, and a reduced batch-to-batch variation must be achieved. This paper addresses ways to reduce variation by controlling the processing conditions, in particular the dissolved oxygen concentration (dO2), and the culture medium. Bone marrow derived hMSCs were cultured in DASGIP DASbox bioreactors on Plastic P-102L microcarriers in FBS-containing and serum free (SFM) media at various dO2 values from 100% to 10%, experiencing the same dO2 value throughout the culture process. The superior control of pH and dO2 in the bioreactor led to improved performances compared to poorly controlled spinner flasks, particularly at reduced dO2 concentrations. At 25% dO2, there was a 300% increase in the BM-hMSC yield in the bioreactor across the two donor BM-hMSCs in SFM compared to FBS-containing medium. Overall, the process yield increased by an average of around 500% for both donors under controlled conditions in SFM at 25% dO2 in the bioreactor compared to the poorly controlled expansion at atmospheric conditions in FBS-containing medium in spinner flasks. Process control significantly reduced the BM-hMSC variation in yield from 79.1% in FBS-containing medium in spinner flasks to <15% in controlled SFM bioreactor culture.

The influence of oxygen delivery during cardiopulmonary bypass on the incidence of delirium in CABG patients; a retrospective study.

Introduction:Postoperative delirium is the most common neurological complication of cardiac surgery. Hypoxia has been shown to increase the risk of postoperative delirium. The possibility to continuously monitor oxygen delivery (DO2) during cardiopulmonary bypass (CPB) offers an adequate approximation of the oxygen status in a patient. This study investigates the role of oxygen delivery during cardiopulmonary bypass in the incidence of postoperative delirium.Methods:Three hundred and fifty-seven adult patients who underwent normothermic coronary artery bypass grafting (CABG) surgery were included in this retrospective study. The nadir indexed DO2 (DO2i) value on bypass, the total time under the critical DO2i level and the area under the curve (AUC) for critical DO2i were determined. Delirium was identified by the postoperative administration of haloperidol.Results:The mean nadir DO2i significantly differed, comparing the group of patients with postoperative delirium to the group without. Multivariate analysis only identified age, pre-existing cognitive impairment, preoperative kidney dysfunction and cross-clamp time as independent risk factors for delirium. The results also indicated that patients of older age were more sensitive to a declined DO2i.Conclusion:A low DO2i during cardiopulmonary bypass is significantly associated with the incidence of postoperative delirium in CABG patients. However, the role of DO2 as an independent predictor of delirium could not be proven.

Does size matter concerning impact of position on oxygenation status in spontaneously breathing patients with unilateral effusion?

BackgroundInconsistent and contradictory findings have appeared in the literature concerning the impact of body position on oxygenation in pleural effusion.MethodsWe attempted to elucidate whether the size of the pleural effusion...

Cerebral microembolic load in open heart surgery with different extracorporeal circulation systems

Somanetics 5100C was used to assess regional tissue oxygen saturation. DO2 and VO2 values to assess the oxygen delivery and consumption were also calculated. The association between cerebral and somatic rSO2 trends and mean arterial pressure, pump flow and blood gases were also studied. Results. it was found that prolonged episodes of decrease of somatic rSO2 during cardiopulmonary bypass with lower haemoglobin levels and DO2 values were strongly associated with occurrence of post-op organ disorders especially acute kidney injury. As the results of the correspondence analysis it was shown that for positive outcome without organ disorders greater importance have absolute values of DO2, VO2 and rSO2 (both cerebral and somatic), but for the poor outcome with complications the length of episodes of rSO2 decrease has the greater influence. It was also found that somatic rSO2 values are not strongly associated with pump flow or mean arterial pressure or arterial pO2. Discussion. the use of continuous monitoring of cerebral and even somatic rSO2 during cardiopulmonary bypass in adults may help the prefusionist to assess the adequacy of tissue oxygenation. To improve the somatic and cerebral rSO2 complex strategy is needed to be worked out because the routine increase of pump or gas flow was shown to be not enough and sometimes controversial [2].

Association of Anemic Hypoxia and Increased Pulmonary Artery Systolic Pressure in Patients With Systemic Lupus Erythematosus.

Pulmonary arterial hypertension (PAH) is a rare but serious complication of systemic lupus erythematosus (SLE). Chronic hypoxia is known to cause PAH resulting from pulmonary vascular remodeling. We investigated the association between anemic hypoxia and PAH in SLE patients. Systolic pulmonary artery pressure (PAP) was measured in 132 SLE patients by echocardiography. Increased PAP was defined as resting PAP > 40 mm Hg. Oxygen delivery (DO2) was estimated as the product of cardiac output and arterial oxygen content. Of 132 patients, 17 (12.9%) had increased PAP, and these patients had significantly lower DO2 values than patients with normal PAP (P = 0.002). The DO2 values inversely correlated with PAP values (γ = -0.308, P < 0.001) and plasma N-terminal pro-brain natriuretic peptide levels (γ = -0.323, P = 0.001), but positively correlated with hemoglobin levels (γ = 0.402, P < 0.001). Compared to those with normal PAP, patients with increased PAP had significantly longer durations of anemia over the preceding 6-24 months. Patients with anemia of longer durations (≥3 months) in the preceding 6 months had a higher risk of increased PAP compared to those with shorter durations (P < 0.001). When SLE patients were divided into 3 groups according to hemoglobin and PAP, serum interleukin-6 (IL-6) levels increased across groups with higher PAP (P = 0.001 for trend), but decreased across tertiles of hemoglobin levels (P = 0.008 for trend). Our data indicate an association between chronic anemic hypoxia and increased PAP in SLE patients and suggest that increased IL-6 might participate in this process.

Performance of a non-invasive methodology for assessing oxygen diffusion in liquid and solid food products

Based on the measurement of local oxygen partial pressure kinetic, a non-invasive methodology was proposed to assess O2 diffusivity (DO2) in liquid, viscous and solid matrices. This new method was compared with a previous invasive method, developed by the same group, based on the same principle. The new method has proven to be essential to measure DO2 in solid food matrices where invasive methods usually failed. It was successfully used to obtain DO2 of cooked ham and processed cheese which were found respectively equal to 0.450 ± 0.004 × 10−9 m2·s−1 and 1.15 ± 0.11 × 10−9 m2·s−1 at 20 °C. DO2 was also evaluated as a function of temperature (from 5 to 30 °C) and viscosity in lipid-based matrices. These results have permitted to determine activation energy of the diffusion and have revealed that increasing viscosity of the lipid matrices tested did not impact their DO2 values.

The energy saving mechanism of gas diffusion electrode based on Pt/C catalyst for saving energy and green electrodeposition of manganese dioxide

The electrodeposition of manganese dioxide is obtained by using Pt/C GDE rather than the traditional electrode (Cu) in order to save energy and protect the environment. Thus, the energy-saving mechanism of Pt/C gas diffusion electrode (Pt/C GDE) in high temperature and strong acid MnSO4 media is studied. The cell voltage and the cathode potential of Pt/C GDE and Cu electrode are tested in 30g/dm3 H2SO4+120g /dm3 MnSO4 at 80±2°C to exhibit the energy-saving effect. The results show that the cell voltage can be reduced more than 1.13V using Pt/C GDE as cathode instead of the traditional electrode (Cu), and the electric energy consumption of electrolysis with Pt/C GDE can save 60% at 80A/m2. The CV curves and polarization curves of Pt/C GDE and the polarization curve of hydrogen evolution reaction on a Cu electrode are researched. The results indicate that the polarization curve of Cu electrode is much more negative than that of the Pt/C GDE at same current density. The reaction of Pt/C GDE is oxygen reduction at the cathode.The amperometric oxygen reduction current of the GDE with Pt/C is about 28 times higher than that of GDE without Pt/C at 0.4V vs. Ag/AgCl. The Pt/C catalyst particle sizes range from 2nm–6nm by HRTEM. The oxygen reduction reaction mechanism of Pt/C GDE is researched in strong acid containing manganese ion by rotating disk electrode (RDE). The DO2 and CO2 values are 0.715×10−9m2s−1 and 3.3 mol·m−3 in electrolyte. Koutecky-Levich analysis indicates that the oxygen reduction reaction of Pt/C GDE adopts a 4electron transfer process as main process as the main process in electrolyte (O2+4H++4e−→2H2O). Therefore, the major causes of the new method for saving energy is that the oxygen reduction reaction of Pt/C GDE, rather than the hydrogen evolution reaction of tradition cathode (Cu), is used, and that the high catalytic activity (the 4-electron transfer process) of Pt/C catalyst also contributes.

FRI0279 Anemic hypoxia is associated with pulmonary arterial hypertension in patients with systemic lupus erythematosus

BackgroundPulmonary arterial hypertension (PAH) is a serious and often fatal complication of systemic lupus erythematosus (SLE), but its pathogenesis is still unclear. Hypoxia-induced pulmonary vascular remodelling has been suggested to...