Oxygen Pressure Difference Research Articles

Carbon Deposition during CO2 Electrolysis in Ni-Based Solid-Oxide-Cell Electrodes

Local gradients within an operating solid oxide electrolyzer cell were studied using current-potential measurements and electrochemical impedance spectroscopy. The cells and operating conditions were closely related to commercial applications. The cells with fuel electrodes of nickel and yttria-stabilized zirconia (Ni-YSZ) cermets were supplied by Haldor Topsoe A/S and the operating conditions were chosen so as to take stack relevant considerations into account. Formation of carbon nanotubes in Ni containing fuel electrodes has previously been observed in co-electrolysis of H2O and CO2 [1]. Hence, the carbon formation threshold in an operating cell was investigated during electrolysis of an idealized reactant atmosphere of CO and CO2. The electrolysis current was gradually increased in steps until the cell voltage spontaneously increased, thereby indicating cell degradation and possibly the onset of carbon deposition. The outlet gas composition at each current step was estimated based on the inlet gas composition and the reactant conversion using Faraday's law. The increase in voltage was observed at lower pCO/pCO2 ratios than that corresponding to the thermodynamic threshold for carbon formation. Electrochemical impedance spectroscopy in both H2/H2O and CO/CO2 revealed an increase in resistance of the fuel electrode after each CO2 electrolysis current-voltage curve, indicating possible carbon deposition. The difference in partial oxygen pressure between inlet and outlet was analyzed to verify carbon deposition. The increase in voltage is likely due to either blocking of the reaction sites by the deposited carbon, or due to the microstructural damage caused by the carbon, or a combination of these. Moreover, the current step-size and step-length was varied to investigate the time-dependence of the detection of carbon deposition. Initial results indicate that for longer current steps, carbon formation is observed at lower pCO/pCO2 ratios. This is related to the rate of carbon deposition and the averaged nature of the cell voltage measurements. Possible reasons for these observations will be discussed in detail. In an attempt to mitigate the degradation due to carbon deposition, the Ni-YSZ electrode was infiltrated with a gadolinium doped ceria (CGO) solution. Initial results indicate that the coking tolerance was not enhanced, but it is still unclear whether infiltrated cells degrade less. However, infiltrated cells display a significant performance enhancement before coking, especially under electrolysis current. The investigation thus indicated carbon formation in the Ni containing fuel electrode before the thermodynamically calculated threshold for average measurements of the cell was reached. The deviation from the average threshold was reproduced on several cells and quantified (figure 1). The observation of carbon formation on a local, microstructural level before the expected thermodynamic threshold for average measurements on the cell level, is of crucial importance when choosing operating conditions for commercial systems. The effect would be even more severe on stack level, where the gas diffusion and temperature gradients are more pronounced. Initial results of the mitigation strategy of infiltrating CGO are negative, but increased performance prior to coking was observed. [1] Y. Tao, S. D. Ebbesen, and M. B. Mogensen, “Carbon Deposition in Solid Oxide Cells during Co-Electrolysis of H2O and CO2” Journal of the Electrochemical Society, vol. 161, pp. F337–F343, Jan. 2014. Figure 1

Antigen avoidance tests for diagnosis of chronic hypersensitivity pneumonitis.

Chronic hypersensitivity pneumonitis (HP) is induced by the inhalation of specific antigens. Patients with chronic HP may be able to improve their prognosis by avoiding these antigens. Chronic HP is often difficult to distinguish from idiopathic interstitial pneumonias (IIPs). This study was performed to find out how antigen avoidance tests contribute to the diagnosis of chronic HP. A retrospective analysis was conducted on 265 patients who underwent 2-week antigen avoidance tests between April 2002 and March 2012. The patients were classified into the following categories: acute HP, chronic HP, collagen vascular disease-associated interstitial pneumonia (CVD-IP), lung dominant connective tissue disease (LD-CTD), and IIPs. The following seven clinical parameters were evaluated: vital capacity, alveolar-arterial oxygen pressure difference, Krebs von den Lungen-6, surfactant protein-D, white blood cell count, C-reactive protein, and body temperature. These parameters were compared between the chronic HP group and a control group consisting of CVD-IP, LD-CTD, and IIPs. One-hundred and ninety-six patients with chronic HP and 43 control subjects were evaluated. All clinical parameters improved significantly in the chronic HP group but showed no significant changes in the control group. Four of the parameters changed significantly compared with the control group. Diagnostic criteria established using these data had a sensitivity of 51.0% and a specificity of 80.7%. It was difficult to diagnose chronic HP based solely on 2-week antigen avoidance tests; however, improved clinical parameters among patients supported the diagnosis of HP.

Low-dose capsaicin decreases lung ischemia-reperfusion injury and underlying mechanism in rats

To explore the effects of low-dose capsaicin (CAP) on lung ischemia-reperfusion (IR) injury and elucidate its possible mechanisms in rats. A total of 32 Sprague-Dawley rats were randomly divided into 4 groups of S (sham thoracotomy and mechanical ventilation for 5.0 h), IR (an occlusion of left pulmonary hilus for 1.0 h followed by reperfusion for 4.0 h), CAP (an injection of CAP at 5.0 min pre-occlusion) and CGRP8-37 group (an injection of CGRP receptor antagonist CGRP8-37 at 10.0 min pre-occlusion followed by the same treatment as CAP group) (n = 8 each). At pre-occlusion, 0.5 h and 4.0 h post-reperfusion, blood samples were collected for blood gas analyses and arterial oxygen pressure (PaO2) and alveolar arterial oxygen difference (A-aDO2) measured. At the end of experiment, lung tissues were obtained to measure the level of tumor necrosis factor alpha (TNF-α), lung tissue wet to dry weight ratio (W/D) and lung histological changes. At 0.5 h post-reperfusion, PaO2 in S group was significantly higher than that in IR, CAP and CGRP8-37 groups ((147.7±32.4) vs (100.8±18.9), (123.9±16.3), (121.0±15.2) mmHg (1 mmHg=0.133 kPa), all P<0.05) and it was higher in CAP group than in IR group (P<0.05); A-aDO2 increased in IR and CGRP8-37 groups versus S group ((151.5±21.9), (134.3±15.1) vs (118.4±19.1) mmHg, both P<0.05). At 4 h post-reperfusion, PaO2 was higher in CAP group than those in IR and CGRP8-37 groups ((146.0±21.1) vs (113.5±21.1), (124.0±16.4) mmHg, both P<0.05). And A-aDO2 in CAP group was lower than those in IR and CGRP8-37 groups ((111.4±23.4) vs (140.8±22.0), (132.7±16.4) mmHg, both P<0.05); the level of TNF-α in CAP group was lower than that in IR group ((2.7±0.9) vs (3.7±1.1) pg/mg, P<0.05); W/D ratios were remarkably higher in IR, CAP and CGRP8-37 groups than that in S group (5.74±0.52, 6.03±0.78, 5.26±0.24 vs 4.87±0.34, all P<0.05), and it was lower in CAP group than in CGRP8-37 group (P<0.05). Under light microscope, the pathological lesions were more severe in IR and CGRP8-37 groups than those in CAP group at 4 h post-reperfusion. Low-dose capsaicin exerted protective effects on lung ischemia reperfusion injury in rats. And it is mediated partially by calcitonin gene-related peptide receptor. The underlying molecular mechanism is involved in suppressed inflammatory response.

Mechanism involved in Danshen-induced fluid secretion in salivary glands.

Danshen's capability to induce salivary fluid secretion and its mechanisms were studied to determine if it could improve xerostomia. Submandibular glands were isolated from male Wistar rats under systemic anesthesia with pentobarbital sodium. The artery was cannulated and vascularly perfused at a constant rate. The excretory duct was also cannulated and the secreted saliva was weighed in a cup on an electronic balance. The weight of the accumulated saliva was measured every 3 s and the salivary flow rate was calculated. In addition, the arterio-venous difference in the partial oxygen pressure was measured as an indicator of oxygen consumption. In order to assess the mechanism involved in Danshen-induced fluid secretion, either ouabain (an inhibitor of Na(+)/K(+) ATPase) or bumetanide (an inhibitor of NKCC1) was additionally applied during the Danshen stimulation. In order to examine the involvement of the main membrane receptors, atropine was added to block the M₃ muscarinic receptors, or phentolamine was added to block the α₁ adrenergic receptors. In order to examine the requirement for extracellular Ca(2+), Danshen was applied during the perfusion with nominal Ca(2+) free solution. Although Danshen induced salivary fluid secretion, 88.7 ± 12.8 μL/g-min, n = 9, (the highest value around 20 min from start of DS perfusion was significantly high vs 32.5 ± 5.3 μL/g-min by carbamylcholine, P = 0.00093 by t-test) in the submandibular glands, the time course of that secretion differed from that induced by carbamylcholine. There was a latency associated with the fluid secretion induced by Danshen, followed by a gradual increase in the secretion to its highest value, which was in turn followed by a slow decline to a near zero level. The application of either ouabain or bumetanide inhibited the fluid secretion by 85% or 93%, and suppressed the oxygen consumption by 49% or 66%, respectively. These results indicated that Danshen activates Na(+)/K(+) ATPase and NKCC1 to maintain Cl(-) release and K(+) release for fluid secretion. Neither atropine or phentolamine inhibited the fluid secretion induced by Danshen (263% ± 63% vs 309% ± 45%, 227% ± 63% vs 309% ± 45%, P = 0.899, 0.626 > 0.05 respectively, by ANOVA). Accordingly, Danshen does not bind with M₃ or α₁ receptors. These characteristics suggested that the mechanism involved in DS-induced salivary fluid secretion could be different from that induced by carbamylcholine. Carbamylcholine activates the M₃ receptor to release inositol trisphosphate (IP3) and quickly releases Ca(2+) from the calcium stores. The elevation of [Ca(2+)]i induces chloride release and quick osmosis, resulting in an onset of fluid secretion. An increase in [Ca(2+)]i is essential for the activation of the luminal Cl(-) and basolateral K(+) channels. The nominal removal of extracellular Ca(2+) totally abolished the fluid secretion induced by Danshen (1.8 ± 0.8 μL/g-min vs 101.9 ± 17.2 μL/g-min, P = 0.00023 < 0.01, by t-test), suggesting the involvement of Ca(2+) in the activation of these channels. Therefore, IP₃-store Ca(2+) release signalling may not be involved in the secretion induced by Danshen, but rather, there may be a distinct signalling process. The present findings suggest that Danshen can be used in the treatment of xerostomia, to avoid the systemic side effects associated with muscarinic drugs.

Characteristics of serum lipid metabolism in patients with autoimmune pulmonary alveolar proteinosis.

To study the serum lipid panels in consecutive autoimmune pulmonary alveolar proteinosis(APAP)patients and analyze their relationship with anti-granulocyte macrophage-colony stimulating factor(GM-CSF)antibody and other markers. Thirty-two non-diabetic APAP patients were enrolled in the study. Serum lipids of these patients and 100 healthy volunteers were tested after an overnight fasting. Anti-GM-CSF antibody levels were measured with enzyme-linked immunosorbent assay. The correlation of serum lipids with lactate dehydrogenase,carcinoembryonic antigen,pulmonary function,and artery blood gas parameters were analyzed. Total cholesterol and low-density lipoprotein cholesterol levels [(5.54±0.99)and(3.73±0.83)mmol/L respectively] were significantly higher in APAP patients than in healthy volunteers [(5.05±0.97)and(3.17±0.89)mmol/L respectively](all P<0.05). High-density lipoprotein cholesterol(HDL-C)level of the APAP group [(1.10±0.18)mmol/L ]was significantly lower than that of the healthy group(P<0.05). Low-density lipoprotein/HDL and total cholesterol/HDL ratios in the APAP group(3.47±0.90 and 5.14±1.12 respectively)were significantly higher than those in the healthy group[(2.63±0.87)and(4.18±1.12)](all P<0.05). There was no significant difference in triglyceride level between the two groups(P>0.05). HDL-C level was negatively correlated with alveolar-arterial oxygen pressure difference(r=-0.436,P<0.05)and positively correlated with arterial oxygen saturation(r=0.459,P<0.05). None of the lipid markers correlated with serum anti-GM-CSF antibody levels(all P>0.05). APAP patients were likely to suffer from disturbed lipid metabolism,which was correlated with disease severity to some degree. Lipid markers deserved more attention in the management of APAP patients.

Is lung diffusing capacity lower in expiratory flow limited women compared to non-flow limited women during exercise?

Women tend to have smaller lungs than men of the same size as well as narrower airways compared to men when matched for the same lung size. Additionally, women with smaller airways relative to lung size are more likely to experience expiratory flow limitation (EFL) as well as exercise-induced arterial hypoxemia (EIAH). One of the possible causes of EIAH includes excessive widening in the alveolar-to-arterial oxygen pressure difference (A-aDO2) due to diffusion limitation. This study investigated if lung diffusing capacity (D LCO) is lower in women with EFL compared to non-flow limited (NEFL) women during exercise. D LCO was measured using the rebreathing technique at rest and at 40, 60, and 80 % of [Formula: see text] on a treadmill in healthy women with EFL (n = 7; 21.6 ± 2.3) and without EFL (NEFL, n = 9; 21.2 ± 2.3). Arterial oxygen saturation was measured using pulse oximetry (SpO2). There was no difference (p > 0.05) in D LCO between groups at rest or during exercise; however, SpO2 was significantly lower in the EFL females compared to NEFL females during exercise. Due to the lack of differences in D LCO between women with EFL and without EFL, our results suggest that this is not a possible cause for the significant differences in SpO2 between the two groups.

Study of the effects of high volume hemofiltration on extra vascular lung water and alveolar-arterial oxygen exchange in patients with septic shock

To explore the effects of high volume hemofiltration (HVHF) on inflammatory factors, extra vascular lung water and alveolar-arterial oxygen exchange in patients with septic shock. The data of 87 patients with septic shock underwent fluid resuscitation admitted to intensive care unit (ICU) of Shandong Provincial Hospital Affiliated to Shandong University were retrospectively analyzed. According to whether HVHF was used or not, all the patients were divided into fluid resuscitation group (n=41) and HVHF group (n=46). The patients in HVHF group received bedside high volume continuous vein-vein hemofiltration for at least 3 days on the basis of fluid resuscitation. The inflammatory factors, indexes of heart function, hemodynamics monitored by pulse-indicated continuous cardiac output (PiCCO), oxygen exchange, the severity of the disease before and after treatment, and 28-day mortality were compared between the two groups. The relationship between extra-vascular lung water index (EVLWI) and alveolar-arterial oxygen pressure difference (P(A-a)DO₂) was analyzed. (1) After treatment, the serum levels of interleukin-6 (IL-6), procalcitonin (PCT), and N-terminal pro-B-type natriuretic peptide (NT(-pro)BNP) in both group were gradually decreased. The IL-6, PCT, and NT(-pro)BNP on the 3rd day after treatment in HVHF group were significantly lower than those in fluid resuscitation group [IL-6 (μg/L): 34.8 ± 15.8 vs. 63.3 ± 21.2, PCT (μg/L): 7.5 ± 6.4 vs. 17.3 ± 11.2, NT(-pro)BNP (μg/L): 561.8 ± 23.7 vs. 584.3 ± 56.7, P<0.05 or P<0.01]. (2) The hemodynamics indexes were improved after treatment in both groups. The levels of intrathoracic blood volume index (ITBVI), EVLWI and pulmonary vascular permeability index (PVPI) on the 3rd day after treatment in HVHF group were significantly lower than those in fluid resuscitation group [ITBVI (mL/m²): 634.2 ± 125.8 vs. 963.8 ± 321.0, EVLWI (mL/kg): 7.5 ± 2.4 vs. 12.3 ± 4.2, PVPI: 2.2 ± 1.2 vs. 4.2 ± 2.0, all P<0.01]. (3) The levels of PA-aDO₂and arterial blood lactic (Lac) were gradually decreased, and oxygenation index (PaO₂/FiO₂) was gradually increased in both groups. Compared with fluid resuscitation group, the P(A-a)DO₂and Lac on the 3rd and the 7th day were significantly declined[P(A-a)DO₂(mmHg, 1 mmHg=0.133 kPa) on the 3rd day: 252.37 ± 29.45 vs. 270.82 ± 38.07, on the 7th day: 181.08 ± 21.81 vs. 221.02 ± 29.13; Lac (mmol/L) on the 3rd day: 3.17 ± 2.03 vs. 4.07 ± 2.43, on the 7th day: 1.95 ± 0.97 vs. 2.45 ± 1.07, P<0.05 or P<0.01], and the PaO₂/FiO₂on the 7th day was significantly elevated (mmHg: 258 ± 41 vs. 178 ± 34, P<0.01). (4) A significant positive correlation was found between EVLWI and P(A-a)DO₂(r=0.693, P=0.001), with the 95% confident interval (95% CI) 0.617-0.773. (5) The condition was improved after treatment in the two groups. The acute physiology and chronic health evaluationII (APACHEII) scores and sepsis-related organ failure assessment (SOFA) scores on the 7th day after treatment in HVHF group were significantly reduced compared with those in fluid resuscitation group (APACHEII score on the 3rd day: 18.2 ± 7.7 vs. 22.4 ± 8.6, on the 7th day: 8.2 ± 3.8 vs. 17.2 ± 6.8; SOFA score on the 3rd day: 13.6 ± 3.4 vs. 15.8 ± 5.0, on the 7th day: 7.6 ± 3.3 vs. 12.8 ± 3.9, P<0.05 or P<0.01). The 28-day mortality in HVHF group was significantly lower than that in fluid resuscitation group [15.22% (7/46) vs. 34.15% (14/41), χ² = 4.242, P=0.038]. HVHF could decrease blood inflammatory factors, and reduce the vaso-permeability and extra vascular lung water with a result of the improvement of the levels of alveolar- arterial oxygen exchange in patients with septic shock and the prognosis at the same time.

Persisting hypoxaemia is an insufficient measure of adverse lung function in very immature infants

BackgroundBronchopulmonary dysplasia (BPD), defined as protracted neonatal hypoxaemia, is considered a risk factor for respiratory disease in adulthood. The relationship between this diagnosis and the actual lung injury appearing in...

Effects of High-Dose Ulinastatin on Inflammatory Response and Pulmonary Function in Patients With Type-A Aortic Dissection After Cardiopulmonary Bypass Under Deep Hypothermic Circulatory Arrest

To investigate effects of high-dose ulinastatin on the release of proinflammatory cytokines and lung injury in patients with aortic dissection after cardiopulmonary bypass (CPB) under deep hypothermic circulatory arrest (DHCA). A prospective, randomized and double-blinded study. A teaching hospital. Thirty-six patients with acute type-A aortic dissection undergoing cardiac surgery using CPB under DHCA. These patients randomly were selected to received total doses of 20,000 units/kg of ulinastatin (n = 18) or 0.9% saline (control, n = 18) at 3 time points (after anesthetic induction, before aortic cross-clamp, and after aortic cross-clamp release). Tumor necrosis factor-alpha, interleukin 6, interleukin 8 and polymorphonuclear neutrophil elastase (PMNE) were measured after anesthetic induction (T0), 30 minutes (T1) after aortic cross-clamp, 3 (T2), 6 (T3) and 9 (T4) hours after weaning from CPB. Except for T1, pulmonary data, such as alveolar-arterial oxygen pressure difference, physiologic deadspace, peak inspiratory pressure, plateau pressure, static compliance and dynamic compliance, were obtained at the same time points. Concentrations of cytokines and PMNE were significantly lower in the ulinastatin group than the control group from T1 to T4, and peaked at T2 between the 2 groups. Compared with the pulmonary data of the control group at T2~T4, postoperative alveolar-arterial oxygen pressure difference, physiologic deadspace, peak inspiratory pressure, and plateau pressure significantly were lower, and static compliance and dynamic compliance higher in the ulinastatin group. Significantly shorter intubation time and intensive care unit stay were found in the ulinastatin group. High-dose ulinastatin attenuates the elevation of cytokines and PMNE, reduces the pulmonary injury and improves the pulmonary function after CPB under DHCA. Consequently, it shortens the time of intubation and intensive care unit stay.

Influence of smoking and obesity on alveolar-arterial gas pressure differences and dead space ventilation at rest and peak exercise in healthy men and women

Besides exercise intolerance, the assessment of ventilatory and perfusion adequacy allows additional insights in the disease pathophysiology in many cardiovascular or pulmonary diseases. Valid measurements of dead space/tidal volume ratios (VD/VT), arterial (a') - end-tidal (et) carbon dioxide (CO2) and oxygen (O2) pressure differences (p(a'-et)CO2) and (p(et-a')O2), and alveolar (A)-a' O2 pressure differences (p(A-a')O2) require using blood samples in addition to gas exchange analyses on a breath-by-breath-basis. Smoking and nutritional status are also important factors in defining disorders. Using a large healthy population we considered the impact of these factors to develop useful prediction equations. Incremental cycle exercise protocols were applied to apparently healthy volunteer adults who did not have structural heart disease or echocardiographic or lung function pathologies. Age, height, weight, and smoking were analysed for their influence on the target parameters in each gender. Reference values were determined by regression analyses. The final study sample consisted of 476 volunteers (190 female), aged 25-85 years. Smoking significantly influences p(A-a')O2 and p(a'-et)CO2 at rest and peak exercise, and VD/VT during exercise. Obesity influences upper limits of VD/VT, p(a'-et)CO2 and p(et-a')O2 at rest as well as p(A-a')O2 and p(et-a')O2 at exercise. Reference equations for never-smokers as well as for apparently healthy smokers considering influencing factors are given. Gender, age, height, weight, and smoking significantly influence gas exchange. Considering all of these factors this study provides a comprehensive set of reference equations derived from a large number of participants of a population-based study.

Impaired endothelium-dependent vasodilator response in patients with pulmonary fibrosis

Recent epidemiological evidence indicates an association between cardiovascular diseases and pulmonary fibrosis. The vascular endothelium acts to maintain vascular homeostasis through multiple mechanisms and impaired endothelial function can contribute to the development, progression and clinical expression of atherosclerosis. We consecutively recruited 39 newly-diagnosed chronic interstitial pneumonitis/fibrosis patients without any specific etiology. We assessed endothelium-dependent vasodilator response of patients using digital pulse amplitude tonometry and compared the reactive hyperemia index (RHI) with age-, sex- and body mass index-matched control subjects (n=30). We further investigated the relationships between RHI and clinical characteristics, laboratory cardiovascular risk factors, disease-related factors and circulating levels of inflammatory biomarkers. RHI was significantly lower in patients with chronic interstitial pneumonitis/fibrosis than in control subjects (p=0.02). While circulating levels of total cholesterol, triglycerides, HbA1c and fasting glucose did not differ significantly between groups, patients with chronic interstitial pneumonitis/fibrosis had significantly lower high density lipoprotein levels and higher low density lipoprotein levels as compared with control subjects. Regarding disease-related factors, RHI was significantly associated with the diffusing capacity for carbon monoxide, alveolar-arterial oxygen pressure difference, 6-min walk distance and end-exercise oxygen saturation. Additionally, circulating levels of intercellular adhesion molecule-1 and vascular cell adhesion molecule-1 were inversely correlated with RHI. We confirmed a possible link between pulmonary fibrosis and cardiovascular disease by demonstrating an impairment of endothelium-dependent vasodilator response, which was significantly associated with the severity of pulmonary fibrosis and circulating levels of adhesion molecules.

Active oxidation of silicon carbide

The active oxidation of SiC has been studied at 1390 and 1490°C, paying particular attention to the active-to-passive and passive-to-active transition points. First the active-to-passive transition for pure silicon was studied at 1290°C. The beginning of passivity is characterized by micron-sized SiO2 rod formation on the surface due to the oxidation of SiO(g), consistent with other investigators. These rods were not observed in the active-to-passive transition for SiC; but they were observed in the passive-to-active transition for SiC. This type of microstructure yields information about the breakdown of the passive film. Unlike pure silicon, at a fixed temperature a substantial difference in the transition oxygen pressure for the active-to-passive and passive-to-active transitions was not observed for SiC. This is due to the fact that both processes are controlled by SiCySiO2 interfacial reactions. Studies were also conducted on active oxidation of SiC with a pre-formed SiO2 scale in order to understand the breakdown of the passive film.

Spectrum of chronic lung disease in a population of newborns with extremely low gestational age

To determine how the ability to oxygenate the blood develops after birth in infants of extremely low gestational age (ELGANs) and to find risk factors for chronic lung disease. A prospective, population-based, cohort study was undertaken in one tertiary-care centre. The alveolar-arterial oxygen pressure difference (AaDO(2)) was monitored. Of 41 survivors, 21 had a period of normal lung function in the first week of life, after which oxygenation deteriorated. Low gestational age and low Apgar score at 5 min were found to be strong and independent predictors of AaDO(2) in the first month of life. Mechanical ventilation did not appear as a risk factor. Lung function at 36 weeks of gestation and duration of oxygen treatment could be better predicted by the severity of lung disease in the first month than by gestational age at birth. Difficulty in oxygenation was a general observation in ELGANs and not only a particular subset. Gestational age and Apgar score were independent predictors of the degree of difficulty over the first month of life. As oxygenation failure often developed after a few days, the process may be possible to treat or prevent once the pathogenesis is known.

Application of improved new mask in noninvasive positive pressure ventilation sputum suction

Objective To explore the effect of improved new mask in noninvasive positive pressure ventilation sputum suction.Methods Among the patients with chronic obstructive pulmonary disease and type Ⅱ respiratory failure,78 patients were selected and divided randomly into observation group (n =38 ) and control group (n =40).Both groups implemented the noninvasive ventilation and symptomatic treatment.The endotracheal suction tube was left in patients for 96 hours,the end of which passes the junction part of the mask and the face.For the control group,the process of ventilation was interrupted for sputum suction,while for the observation group; the process of ventilation kept on without interruption due to the side hole on the mask for suction.In the interval of sputum suction,the same airway humidification fluid was injected into the suction tube regularly for both groups.Results When the observation group and the control group had accepted the noninvasive ventilation simultaneously for 24 hours,the oxygen and carbon dioxide partial pressure difference was not statistically significant(t =0.84,1.07;P ＞ 0.05).While for 48 hours,the oxygen and carbon dioxide partial pressure difference was statistically significant [ (61.53 ±9.94) mm Hg versus (56.57 ± 11.19) mm Hg,t =2.07,P ＜ 0.05 ; (64.02 ± 10.37 ) mm Hg versus ( 69.55 ± 12.73 ) mm Hg,t =2.10,P ＜ 0.05 ].and for 96 hours,the oxygen and carbon dioxide partial pressure difference was also statistically significant [ (69.35 ±9.37) mm Hg versus (60.57 ± 10.64) mm Hg,t =3.87,P ＜ 0.01 ; ( 55.82 ± 10.58 ) mm Hg versus ( 61.55 ±11.73 ) mm Hg,t =3.03,P ＜ 0.01 ].The difference of the time it took for the patients to got conscious in both groups was statistically significant[ (21.21 ±7.24) h versus (25.35 ±9.28) h,t =2.17,P ＜0.05].The difference of the number of cases with the application of invasive ventilation in the end of two groups was statistically significant (x2 =4.78,P ＜ 0.05 ).The difference of the total time with the application of positive ventilation of two groups was statistically.significant [ ( 152.23 ± 25.91 ) h versus ( 169.57 ± 33.49 ) h,t =2.54,P ＜ 0.05 ].Conclusions The mask with a side hole for sputum suction and endotracheal suction tubes can be applied to the patients of the chronic obstructive pulmonary disease combined with the Ⅱ respiratory failure.Without the interruption of the noninvasive ventilation,sputum suction has significant reduction in complications,and the patients can have a shorter recovery time,better treatment effect,and smaller rate of invasive ventilation. Key words: Positive-pressure respiration; Masks; Nursing; Sputum suctioning

Serum level of soluble CX3CL1/fractalkine is elevated in patients with polymyositis and dermatomyositis, which is correlated with disease activity

IntroductionPolymyositis (PM) and dermatomyositis (DM) are chronic inflammatory muscle diseases, in which chemokines are thought to contribute to inflammatory cell migration into muscle. In this study, we retrospectively analyzed the expressions of CX3CL1/fractalkine and its corresponding receptor, CX3CR1, in muscle and lung with interstitial lung disease (ILD) of PM patients and DM patients, and determined the correlation between serum soluble CX3CL1 level and disease activity.MethodsExpressions of CX3CL1 and CX3CR1 in muscle and lung tissue were analyzed by immunohistochemistry. Serum CX3CL1 concentrations were measured by ELISA. For evaluation of patients' disease activity, serum creatinine kinase, manual muscle testing, and the alveolar-arterial oxygen pressure difference were used independently.ResultsCX3CL1 was expressed on infiltrated mononuclear cells and endothelial cells in muscle affected by PM and DM and in lung with ILD, whereas CX3CR1 was expressed on some CD4+ T cells, a majority of CD8+ T cells, and most macrophages in muscle, and on infiltrated mononuclear cells in the lung. Serum soluble CX3CL1 was significantly higher in PM patients and DM patients than in healthy controls. The CX3CL1 level was correlated with serum creatinine kinase and manual muscle testing score. In patients with PM and DM with ILD, serum CX3CL1 was also correlated with alveolar-arterial oxygen pressure difference. Furthermore, CX3CL1 was significantly decreased after conventional treatment.ConclusionsThe interaction between CX3CL1 and CX3CR1 might contribute to the inflammatory cell infiltration into affected muscle and lung with ILD in PM patients and DM patients. Serum CX3CL1 level could be a surrogate marker of disease activity.

The effects of joint administration of 6% hydroxyethyl starch 130/0.4 and high-volume hemofiltration on patients with acute lung injury and acute kidney injury

To evaluate the effects of administration of 6% hydroxyethyl starch (6% HES 130/0.4, voluven) in combination with high volume hemofiltration (HVHF) in patients with ALI and AKI. One hundred and eight patients with acute lung injury (ALI) and acute kidney injury (AKI) were enrolled from Department of Intensive Care Unit (ICU) of the provincial Hospital Affiliated to Shandong University between August 2006 and May 2011. The patients were randomly divided into two groups A (n = 68) and B (n = 40) to receive voluven (i.v., for volume resuscitation) and voluven+HVHF for 72 hours. The arterial blood lactate concentration (Lac), high sensitivity C-reactive protein (hs-CRP) serum concentration, pulmonary function index alveolar-arterial oxygen pressure difference [P(A-a)DO2] and oxygenation index (OI), as well as kidney function index serum cystatin C (Cyst C) and serum creatinine clearance rate (CCr) were measured at the time of admission and 72 hours after the treatment for statistical analysis. In comparison with group A, group B had significantly (all P < 0.01) lower mean value in the level of arterial Lac (mmol/L: 1.7 ± 0.7 vs. 2.7 ± 1.5), serum hs-CRP (mg/L: 35.8 ± 18.8 vs. 99.5 ± 20.4), P(A-a)DO2 (mm Hg, 1 mm Hg=0.133 kPa: 115.5 ± 23.1 vs. 155.4 ± 27.4), Cyst C (mg/L: 2.06 ± 1.12 vs. 3.95 ± 2.06) and significantly higher (both P < 0.01) mean value of OI (mm Hg: 295.2 ± 38.8 vs. 239.5 ± 32.7) and CCr (ml/min: 108.71 ± 31.33 vs. 90.21 ± 30.35) 72 hours after treatment. The mortality rate of group B was significantly lower than group A [10.00%(4/40) vs. 29.41%(20/68), P < 0.05] 7 days after the admission. 6% HES 130/0.4 in combination with HVHF could improve the lung and kidney function of the patients with ALI and AKI, prevent the development of multiple organ dysfunction syndrome (MODS), therefore improve the survival rate of these patients.

Effect of Subzero-Balanced Ultrafiltration on Lung Gas Exchange Capacity after Cardiopulmonary Bypass in Adult Patients with Heart Valve Disease

This study was conducted to evaluate the effect of a new ultrafiltration technique--the subzero-balanced ultrafiltration (SBUF)--on lung gas exchange capacity after cardiopulmonary bypass (CPB) in adult patients with heart valve disease. Attenuation of lung gas exchange capacity is one of the most common manifestations of an inflammatory response after CPB. Ninety-four patients who required CPB for cardiac surgery were randomized into 2 groups according to whether they received SBUF. Gas exchange capacity expressed as the oxygen index (OI), the respiratory index (RI), and the alveolar-arterial oxygen pressure difference (P(A-a)O2) were measured after intubation (T1), at the termination of CPB (T2), on admission to the intensive care unit (ICU) (T3), at postoperative hour 6 (T4), and at postoperative hour 12 (T5). There were no significant differences in gas exchange capacity between the 2 groups at T1, T4, and T5. CPB produced significant changes in OI, RI, and P(A-a)O2 in the control group, whereas these changes were not significantly different in the study group. The OI in the study group was significantly higher at T2, and RI and P(A-a)O2 were significantly lower at T2 and T3. In the study group, the intubation time was shorter, and the transfusion volume within 24 hours postoperatively was less. The 2 groups were comparable with respect to the incidence of respiratory complications, length of stay in the ICU, duration of hospital stay, need for infusions of inotropic agents, and drainage volumes within 24 hours postoperatively. SBUF during CPB can produce an immediate improvement in lung gas exchange capacity, which may effectively minimize pulmonary dysfunction in adult patients undergoing cardiac surgery.

Effects of high-volume hemofiltration on alveolar-arterial oxygen exchange in patients with refractory septic shock.

High-volume hemofiltration (HVHF) is technically possible in severe acute pancreatitis (SAP) patients complicated with multiple organ dysfunction syndrome (MODS). Continuous HVHF is expected to become a beneficial adjunct therapy for SAP complicated with MODS. In this study, we aimed to explore the effects of fluid resuscitation and HVHF on alveolar-arterial oxygen exchange, the Acute Physiology and Chronic Health Evaluation II (APACHE II) score in patients with refractory septic shock. A total of 89 refractory septic shock patients, who were admitted to ICU, the Provincial Hospital affiliated to Shandong University from August 2006 to December 2009, were enrolled in this retrospective study. The patients were randomly divided into two groups: fluid resuscitation (group A, n=41), and fluid resuscitation plus high-volume hemofiltration (group B, n=48). The levels of O2 content of central venous blood (CcvO2), arterial oxygen content (CaO2), alveolar-arterial oxygen pressure difference P(A-a)DO2, ratio of arterial oxygen pressure/alveolar oxygen pressure (PaO2/PaO2), respiratory index (RI) and oxygenation index (OI) were determined. The oxygen exchange levels of the two groups were examined based on the arterial blood gas analysis at different times (0, 24, 72 hours and 7 days of treatment) in the two groups. The APACHE II score was calculated before and after 7-day treatment in the two groups. The levels of CcvO2, CaO2 on day 7 in group A were significantly lower than those in group B (CcvO2: 0.60±0.24 vs. 0.72±0.28, P<0.05; CaO2: 0.84±0.43 vs. 0.94±0.46, P<0.05). The level of oxygen extraction rate (O2ER) in group A on the 7th day was significantly higher than that in group B (28.7±2.4 vs. 21.7±3.4, P<0.01). The levels of P(A-a)DO2 and RI in group B on the 7th day were significantly lower than those in group A. The levels of PaO2/PaO2 and OI in group B on 7th day were significantly higher than those in group A (P<0.05 or P<0.01). The APACHE II score in the two groups reduced gradually after 7-day treatment, and the APACHE II score on the 7th day in group B was significantly lower than that in group A (8.2±3.8 vs. 17.2±6.8, P<0.01). HVHF combined with fluid resuscitation can improve alveolar-arterial-oxygen exchange, decrease the APACHE II score in patients with refractory septic shock, and thus it increases the survival rate of patients.

Effects of fluid resuscitation and hemofiltration on Alveolar-arterial oxygen pressure exchange

Objective To evaluate the effects of fluid resuscitation and large-volume hemofiltration (HVHF) on the Alveolar-arterial oxygen exchange in patients with refractory septic shock. Method A total of 89 intensive care patients with refractory septic shock treated with fluid resuscitation and/or HVHF were enrolled between August 2006 and December 2009. All the patients were randomly divided into two groups. In group A, patients were treated with fluid resuscitation, n = 41 cases) and in group B, patients were treated with large-volume hemofiltration and fluid resuscitation, n =48). The O2 content of central venous blood(CcvO2), arterial oxygen content (CaO2), Alveolar-arterial oxygen pressure difference (P(A-a)DO2), the ratio of arterial oxygen pressure/alveolar oxygen pressure (PaO2/PAO2), respiratory index (RI) and oxygenation index (OI) were checked. The levels of oxygen exchange in two groups were detected by arterial blood gas analysis before treatnent, 24 hour, 72 hour and 7 days after treatment. The APACHE Ⅱ scores in patients with refractory septic shock were measured before and the 7th day after treatment with HVHF and/or fluid resuscitation respectively. Data were analyzed by using t -test and chi-square test to compare the differences and ratio between two groups and were expressed in mean ± standard deviation, and the analysis of variance was done with SPSS version 12.0 software. Results ① The differences in CcvO2 and CaO2 between two groups were[(0.60±0.24) vs. (0.72±-0.28), P ＜0.05 and (0.84±0.43) vs. (0.94±0.46), P ＜0.05]; and the oxygen extraction rates (O2ER) were significantly different between two groups [(28.7±2.4) vs. (21.7±3.4), P<0.01];② The levels of P(A-a)DO2、ratio of PaO2/PAO2、RI and OI in group B were reduced more significantly than in group A (P<0.05 or P<0.01);③The APACHE Ⅱ scores in both groups were gradually reduced after treatment for 7 days, and the APACHE Ⅱscore in group B on the 7th day of treatment were lower than that in group A[(17.2 ± 6.8) vs. (8.2 ± 3.8), P ＜ 0.01]. Conclusions Fluid resuscitation and HVHF could improve alveolar-arterial-oxygen exchange in patients with refractory septic shock, and at the same time decreased the APACHE Ⅱ scores, improving the survival rate of patients. Key words: Fluid resuscitation; High-volume hemofiltration(HVHF); Septic shock; Oxygen extraction rate (O2ER); Alveolar-arterial-oxygen exchange; Ratio of PaO2/PAO2; Respiratory index (RI); Oxygenation index (OI); Acute physiology and chronic health evaluation Ⅱ(APACHEⅡ)

Prior intense exercise reduces arterial carbon dioxide pressure in extreme obesity

Unlike normal weight individuals, individuals with extreme obesity do not show a decrease in arterial carbon dioxide pressure (PaCO₂) from rest to peak exercise. This indicates that breathing is compromised. The objective of this study was to determine if prior high intensity exercise lowers PaCO₂ in comparison with a first bout, normalized for the same metabolic rate. Oxygen consumption during incremental, ramped exercise was matched to constant workload exercise (75% of peak power). Both protocols were to volitional exhaustion 39 ± 8 min apart. Eleven obese subjects (BMI = 47 ± 8 kg/m², aerobic capacity = 2.3 ± 0.6 L/min) were evaluated. Forty paired samples were obtained at the same metabolic rate between the two protocols. The mean absolute difference and 95% CI were large for arterial oxygen pressure (PaO₂) = 9 (6, 11) mmHg and alveolar to arterial oxygen pressure difference (AaDO2) = 7 (5, 8) mmHg. The mean absolute difference for arterial oxyhemoglobin saturation (%SaO₂) = 0.5 (0.4, 0.7) %; PaCO2 = 4 (3, 4) mmHg; physiological dead space to tidal volume ratio (VD/VT) = 0.04 (0.03, 0.05); and alveolar ventilation (VA) = 3 (2, 4) L/min. The recovery period after the first bout of exercise reduced the PaCO₂ by 3 mmHg when matched for similar metabolic rates. Constant workload exercise predicted VA, %SaO2, V(D)/V(T), and PaCO₂, but not PaO₂ or AaDO₂ during incremental exercise at similar metabolic rates. Given a sufficient chemical stimulus, obese subjects will attempt to breathe more, although this does not mean more VA, which removes CO₂.