Low-Temperature Treatment of Boehmitic Bauxite Using the Bayer Reductive Method with the Formation of High-Iron Magnetite Concentrate.

The Bayer process is the main method of alumina production worldwide. The use of low-quality bauxites for alumina production results in the formation of a significant amount of technogenic waste-bauxite residue (BR). The Bayer reductive method is one possible way to eliminate BR stockpiling, but it requires high-pressure leaching at temperatures higher than 220 °C. In this research, the possibility of boehmitic bauxite atmospheric pressure leaching at both the first and second stages or high-pressure leaching at the second stage with the simultaneous reduction of hematite to magnetite was investigated. Bauxite and solid residue after NaOH leaching were characterized using XRD, SEM-EDS, and Mössbauer spectroscopy methods. The first stage of leaching under atmospheric pressure with the addition of Fe(II) species in a strong alkali solution (330-400 g L-1 Na2O) resulted in a partial reduction of the iron minerals and an extraction of more than 60% of Si and 5-25% of Al (depending on caustic modulus of solution) after 1 h. The obtained desilicated bauxite was subjected to atmospheric leaching at 120 °C in a strong alkali solution (350 g L-1) or high-pressure leaching at 160-220 °C using the Bayer process mother liquor in order to obtain a concentrate with a magnetite content higher than 83 wt. %.

High-Iron Bauxite Residue (Red Mud) Valorization Using Hydrochemical Conversion of Goethite to Magnetite.

Bauxite residue (BR), also known as red mud, is a byproduct of the alumina production using the Bayer process. This material is not used to make iron or other iron-containing products worldwide, owing to its high content of sodium oxide and other impurities. In this study, we investigated the hydrochemical conversion of goethite (FeOOH) to magnetite (Fe3O4) in high-iron BR from the Friguia alumina refinery (Guinea) by Fe2+ ions in highly concentrated alkaline media. The simultaneous extraction of Al and Na made it possible to obtain a product containing more than 96% Fe3O4. The results show that the magnetization of Al-goethite and Al-hematite accelerates the dissolution of the Al from the iron mineral solid matrix and from the desilication product (DSP). After ferrous sulfate (FeSO4·7H2O) was added directly at an FeO:Fe2O3 molar ratio of 1:1 at 120 °C for 150 min in solution with the 360 g L-1 Na2O concentration, the alumina extraction ratio reached 96.27% for the coarse bauxite residue size fraction (Sands) and 87.06% for fine BR obtained from red mud. The grade of iron (total iron in the form of iron elements) in the residue can be increased to 69.55% for sands and 58.31% for BR. The solid residues obtained after leaching were studied by XRD, XRF, TG-DTA, VSM, Mössbauer spectroscopy, and SEM to evaluate the conversion and leaching mechanisms, as well as the recovery ratio of Al from various minerals. The iron-rich residues can be used in the steel industry or as a pigment.

High-Selective Extraction of Scandium (Sc) from Bauxite Residue (Red Mud) by Acid Leaching with MgSO4.

Bauxite residue, also known as red mud (RM), from alumina production is the most promising technogenic material for the production of scandium (Sc) and other rare earth elements (REEs). Conveniently, RM is processed by using a strong acid (pH < 2.5), which lead to co-dissolution of iron and other undesirable major components. In this work, for the first time, the possibility of selective extraction of scandium from red mud by using highly diluted acid (pH > 4) in the presence of MgSO4 was shown. The effect of temperature (40-80 °C), time (0-60 min), pH (2-5), and the MgSO4 concentration (12-36 g L-1) on Sc extraction efficiency was evaluated. It was shown that Sc extraction was higher than 63% even at a pH of 4, at 80 °C, after 1 h, while more than 80% could be extracted at a pH of 2. Iron extraction reduced from 7.7 to 0.03% by increasing the pH from 2 to 4. The kinetics study using the shrinking core model (SCM) has shown that diffusion through a product layer is a rate-limiting stage of the process at high temperatures (>60 °C) and low pH (<3), whereas, at lower temperatures and higher pH values, the leaching rate is limited by diffusion through the liquid film.

Selective Scandium (Sc) Extraction from Bauxite Residue (Red Mud) Obtained by Alkali Fusion-Leaching Method.

Bauxite residue, known as "red mud," is a potential raw material for extracting rare-earth elements (REEs). The main REEs (Sc, Y, La, Ce, Nd, Nb, and Sm) from the raw bauxite are concentrated in RM after the Bayer leaching process. The earlier worldwide studies were focused on the scandium (Sc) extraction from RM by concentrated acids to enhance the extraction degree. This leads to the dissolution of major oxides (Fe2O3 and Al2O3) from RM. This article studies the possibility of selective Sc extraction from alkali fusion red mud (RMF) by diluted nitric acid (HNO3) leaching at pH ≥ 2 to prevent co-dissolution of Fe2O3. RMF samples were analyzed by X-ray fluorescence spectrometry (XRF), X-ray diffraction (XRD), electron probe microanalysis (EPMA), and inductively coupled plasma mass spectrometry (ICP-MS). It was revealed that Sc concentration in RMF can reach up to 140-150 mg kg-1. Sc extraction was 71.2% at RMF leaching by HNO3 at pH 2 and 80 °C during 90 min. The leaching solution contained 8 mg L-1 Sc and a high amount of other REEs in the presence of relatively low concentrations of impurity elements such as Fe, Al, Ti, Ca, etc. The kinetic analysis of experimental data by the shrinking core model showed that Sc leaching process is limited by the interfacial diffusion and the diffusion through the product layer. The apparent activation energy (Ea) was 19.5 kJ/mol. The linear dependence of Sc extraction on magnesium (Mg) extraction was revealed. According to EPMA of RMF, Sc is associated with iron minerals rather than Mg. This allows us to conclude that Mg acts as a leaching agent for the extraction of Sc presented in the RMF in an ion-exchangeable phase.

Rare-Earth Elements Extraction from Low-Alkali Desilicated Coal Fly Ash by (NH4)2SO4 + H2SO4.

Coal fly ash (CFA) obtained from pulverized coal furnaces is a highly refractory waste that can be used for alumina and rare-earth elements (REEs) extraction. The REEs in this type of CFA are associated with a mullite and amorphous glassy mass that forms a core-shell structure. In this research, it was shown that complete dissolution of amorphous aluminosilicates from the mullite surface with the formation of the low-alkali mullite concentrate prior to sulfuric acid leaching with the addition of (NH4)2SO4 helps to accelerate the extraction of REEs. The extraction degree of Sc and other REEs reaches 70-80% after 5 h of leaching at 110 °C and acid concentration of 5 M versus less than 20% for the raw CFA at the same conditions. To study the leaching kinetics of the process, the effects of temperature (90-110 °C), liquid-to-solid ratio (5-10), and leaching time (15-120 min) on the degrees of Al and rare-earth elements (REEs) extraction were evaluated. After 120 min of leaching at 110 °C and L/S ratio = 10, the extraction of Al was found to be lower than 30%. At the same time, total REEs (TREE) and Fe extraction were greater than 60%, which indicates that a part of the TREE was transferred into the acid soluble phase. After leaching, the residues were studied by laser diffraction (LD), X-ray diffraction (XRD), X-ray fluorescence (XRF), and scanning electron microscopy (SEM-EDS) to evaluate the leaching mechanism and the solubility of Al- and Fe-containing minerals, such as mullite, hematite, and amorphous aluminosilicate.

Kinetics Study of Al Extraction from Desilicated Coal Fly Ash by NaOH at Atmospheric Pressure.

The most promising source of alumina in the 21st century is the coal fly ash (CFA) waste of coal-fired thermal plants. The methods of alumina extraction from CFA are often based on the pressure alkaline or acid leaching or preliminary roasting with different additives followed by water leaching. The efficiency of the alumina extraction from CFA under atmospheric pressure leaching is low due to the high content of acid-insoluble alumina phase mullite (3Al2O3·2SiO2). This research for the first time shows the possibility of mullite leaching under atmospheric pressure after preliminary desilication using high liquid to solid ratios (L:S ratio) and Na2O concentration. The analysis of the desilicated CFA (DCFA) chemical and phase composition before and after leaching has been carried out by inductively coupled plasma optical emission spectrometry (ICP-OES) and X-ray diffraction (XRD). The morphology and elemental composition of solid product particles has been carried out by scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDX). An automated neural network and a shrinking core model (SCM) were used to evaluate experimental data. The Al extraction efficiency from DCFA has been more than 84% at T = 120 °C, leaching time 60 min, the L/S ratio > 20, and concentration of Na2O-400 g L-1. The kinetics analysis by SCM has shown that the surface chemical reaction controls the leaching process rate at T < 110 °C, and, at T > 110 °C after 15 min of leaching, the process is limited by diffusion through the product layer, which can be represented by titanium compounds. According to the SEM-EDX analysis of the solid residue, the magnetite spheres and mullite acicular particles were the main phases that remained after NaOH leaching. The spheric agglomerates of mullite particles with non-porous surface have also been found.

Influence of Adding Modifying Elements and Homogenization Annealing on Laser Melting Process of the Modified AlZnMgCu with 4%Si Alloys.

AlZnMgCu, the high-strength aluminum alloy, is unsuitable for laser melting applications due to its high hot cracking sensitivity and large solidification temperature range. Adapting this alloy for laser melting processing is a high-demand research issue for extending its use. Thus, this paper investigates the effect of adding 4%Si, 4%Si-Sc+Zr, 4%Si-Ti+B, and homogenization annealing on the laser melting process (LMP) of AlZnMgCu alloy. Homogenization annealing at 500 °C for 6.5 h was selected to dissolve most of the low melting temperature phases into the grain matrix and perform stable alloys for the LMP. The pulsed laser melting process (PLM) was performed on the as-casted and the homogenized samples. The microstructures of the as-casted, the homogenized alloys, and after the LMP were evaluated. In addition, the hardness of the base metal (BM) and laser melted zone (LMZ) were measured. The results revealed that the microstructure was enhanced and refined in the as-cast state by adding the modifiers due to the increasing nucleation potency of solidification sites and the formation of primary Al3(Ti, Zr, Sc) phases. The average grain size was decreased by 15.6 times when adding 4%Si + 0.4%Zr + 0.29%Sc, while it decreased by 10.2 times when adding 4%Si + 1%Ti + 0.2%B. The LMZ of the as-casted samples exhibited a non-uniform distribution of the grains and the elements after the LMP. This was attributed to the evaporation of Zn, Mg during the high laser power process besides the non-uniform distribution of elements and phases in samples during casting. After the laser treating of the homogenized samples with 4%Si-Sc + Zr, uniform columnar grains were formed in the direction of the laser. The presence of Ti and B changed the crystallization nature, resulting in the LMZ with very fine and equiaxed grains due to forming many nucleation centers during solidification. The hardness values have positively increased due to Si addition and adding a combination of Ti + B and Sc + Zr. The maximum hardness was 153.9 ± 5 HV achieved in the LMZ of the homogenized samples of 4%Si + 1%Ti + 0.2%B.

Brain Oxygen Supply in Older Adults During Coronary Artery Bypass Grafting.

OBJECTIVES: To evaluate the dynamics of the cerebral oxygen supply in patients aged ≥65 years, during coronary artery bypass grafting (CABG), and to test the hypothesis that lower intraoperative brain oxygen saturation is associated with postoperative neurological complications. DESIGN: Prospective cohort study. SETTING: The E. Meshalkin National Medical Research Center of the Ministry of Health of the Russian Federation, Novosibirsk, Russia. PARTICIPANTS: The study comprised 200 elderly patients who underwent CABG between April, 2018 and November, 2019. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: The regional hemoglobin oxygen saturation (rSO2, %) of the right and left brain hemispheres were assessed during the intraoperative period using bilateral near-infrared spectroscopy. Furthermore, neurological complications during hospitalization were evaluated. At the anesthesia induction stage, the average levels of rSO2 for the right and left hemispheres were within 65% and did not differ significantly at any stage of CABG (p>0.05). The risk of neurological complications was associated with rSO2 decrease during cardiopulmonary bypass (CPB). An increased risk was associated with rSO2 decrease by 20% or more during CPB, relative to the stage of anesthesia induction, which was observed in 19% of patients. CONCLUSIONS: In elderly patients, the decrease in rSO2 during CPB is associated with an increased risk of neurological complications during hospitalization. This risk increases with a decrease in rSO2 by 20% or more during CPB relative to the stage of anesthesia induction, by a 5-fold and 7-fold for the left and right hemispheres, respectively.

Evaluation of the Microstructure and Mechanical Properties of a New Modified Cast and Laser-Melted AA7075 Alloy.

The mechanical properties and microstructure of as-cast and homogenized AA7075 were investigated. This alloy was modified by adding transition elements 0.3%Sc + 0.5%Zr, 1%Ti + 0.2%B, and 1%Fe + 1%Ni for use in additive manufacturing applications. After adding Ti + B and Sc + Zr, the structure became uniform and finer with the formation of the Al3(Sc, Zr) and TiB2 phases. Coarse structures were obtained with the formation of an extremely unfavorable morphology, close to a needle-like structure when Fe + Ni was added. The mechanical properties of the modified alloys were increased compared to those of the standard alloy, where the best ultimate tensile strength (UTS) and yield strength (YS) were obtained in the AA7075-TiB alloy compared to the standard alloy in as-cast and homogenized conditions, and the highest hardness value was provided by Fe + Ni additives. The effect of the laser melting process on the microstructure and mechanical properties was investigated. Single laser melts were performed on these alloys using 330 V and a scanning speed of 8 mm/s. During the laser melting, the liquation of the alloying elements occurred due to non-equilibrium solidification. A change in the microstructures was observed within the melt zone and heat-affected zone (HAZ). The hardness of the laser-melted zone (LMZ) after adding the modification elements was increased in comparison with that of the standard alloy. Corrosion testing was performed using a solution of 100 mL distilled water, 3.1 g NaCl, and 1 mL HCl over 5, 10, and 30 min and 1 and 2 h. The corrosion resistance of the alloy modified with FeNi was low because of the non-uniform elemental distribution along the LMZ, but in the case of modification with ScZr and TiB, the corrosion resistance was better compared to that of the standard alloy.

Health-related quality of life one year after surgical treatment of the type I chronic aortic dissection.

BACKGROUND: The purpose of our study was to assess the health-related quality of life (HRQoL) in patients with type I chronic aortic dissection before and one year after prosthetics of the aorta, and to test the hypothesis that long-term postoperative parameters of HRQoL are affected by clinical determinants related to the underlying disease, intraoperative characteristics, and complications of the early postoperative period. METHODS: This prospective cohort study included 82 patients with type I chronic aortic dissection. HRQoL parameters were examined using the Short-Form 36 Health Survey Questionnaire before and one year after surgery. RESULTS: Patients with aortic dissection one year after surgery demonstrated an improvement in many HRQoL parameters, including two summary measures of the questionnaire - Physical component summary (PCS) and Mental component summary (MCS). A lower level of PCS and MCS at the preoperative stage significantly predicted lower values of these indices for a long time after aortic prosthetics. The neurological complications in the early postoperative period were the factor affecting the MCS after surgery. Moreover, the neurological complications and the presence of coronary artery disease increased the risk of the adverse outcomes, including aortic related death and significant decrease of MCS or aortic related death and significant decrease of PCS one year after the operation, respectively. CONCLUSIONS: Surgical treatment in patients with type I chronic aortic dissection leads to an increase of many HRQoL parameters. Factors affecting MCS and PCS one year after surgery included the neurological complications and lower level of the MCS and PCS at the preoperative stage. Furthermore, the neurological complications and the presence of coronary artery disease increased the risk of the combined endpoints - aortic related death and significant decrease of MCS or aortic related death and significant decrease of PCS one year after the operation, respectively.

Effect of transcatheter aortic valve implantation on health-related quality of life in older adults with multimorbidity.

PURPOSE: The purpose of this study was to determine the effect of transcatheter aortic valve implantation on health-related quality of life in older adults with multimorbidity and to evaluate the predictive factors for postoperative quality of life impairment in such patients. MATERIAL AND METHOD: This study included 141 older adults with severe aortic stenosis scheduled for elective transcatheter aortic valve implantation. Quality of life was examined in all patients using the Short-Form 36 Health Survey Questionnaire, before and 2 years after surgery. Comorbidity was assessed using the Charlson Comorbidity Index. RESULTS: In older adult patients with aortic stenosis and multimorbidity, transcatheter aortic valve implantation significantly improved both physical and mental components of quality of life 2 years after surgery. A Charlson Comorbidity Index ≥5 points was independently associated with the absence of positive dynamics in Physical Health score [odds ratio (OR) 0.38 (0.20-0.75), p = 0.007]. Charlson Comorbidity Index ≥5 points [OR 0.31 (0.19-0.58), p = 0.026] and new-onset arrhythmia [OR 0.54 (0.38-0.78), p = 0.017] were independent predictors of the absence of positive dynamics in Mental Health score after transcatheter aortic valve implantation. CONCLUSIONS: High-level comorbidity (Charlson Comorbidity Index ≥5 points) predicts both Physical and Mental Health scores for quality of life impairment following transcatheter aortic valve implantation in older adults, and new-onset arrhythmia predicts the Mental Health score for quality of life impairment following transcatheter aortic valve implantation in these patients.

Determinants of Health-Related Quality of Life 1 Year after Pulmonary Thromboendarterectomy.

BACKGROUND: Pulmonary thromboendarterectomy (PTE) is a recognized treatment for patients with chronic thromboembolic pulmonary hypertension (CTEPH), with good long-term hemodynamic results. The aim of this study was to test the hypothesis that the dynamics of health-related quality of life (QoL), 1 year after PTE, depend both on the clinical determinants associated with the underlying disease and the adverse events occurring in the early postoperative period. METHODS: This prospective cohort study included 136 patients with CTEPH. All patients before and after PTE (1-year follow-up) were examined in terms of QoL, by using the Short Form 36 Health Survey Questionnaire. RESULTS: One year after PTE, a significant improvement in the QoL of patients was observed in all subscales of the Short Form 36 Health Survey Questionnaire, except in the general health scale. Multivariate analysis showed that the predictors adversely affecting the dynamics of QoL after PTE were the presence of comorbidities (such as chronic obstructive pulmonary disease [COPD] and coronary artery disease) and early postoperative complications (specific ones for this category of patients are residual pulmonary hypertension and neurological complications, and nonspecific ones are atrial fibrillation and heart failure). CONCLUSIONS: The determinants that affect the dynamics of QoL 1 year after PTE in patients with CTEPH were the presence of comorbidities (COPD and coronary artery disease) and adverse events in the early postoperative period (residual pulmonary hypertension, neurological complications, atrial fibrillation, and heart failure).

Chronic obstructive pulmonary disease in patients with chronic thromboembolic pulmonary hypertension: Prevalence and implications for surgical treatment outcome.

OBJECTIVE: The aim of our study was to investigate the prevalence of chronic obstructive pulmonary disease (COPD) in patients with chronic thromboembolic pulmonary hypertension (CTEPH) and examine their impact on the results of pulmonary thrombendarterectomy (PEA). METHODS: We enrolled 136 patients with CTEPH who scheduled for elective PEA. Pulmonary function tests (PFTs) including full-body plethysmography with bronchodilation test and lung diffusion capacity assessment were performed in all patients prior to surgery treatment. The diagnosis of COPD was verified in accordance with the recommendations of the Global Initiative for Chronic Obstructive Lung Disease 2017. The effect of COPD on perioperative characteristics, complications, in-hospital and one-year mortality of patients with CTEPH were analysed. RESULTS: In the study group with CTEPH the prevalence of COPD was 23%. In 13% of patients, COPD was first detected. The results of PFTs showed more severe airflow limitations with obstructive pattern in patients with concomitant COPD, as well as a more pronounced decrease in the lung diffusion capacity. The presence of COPD in patients with CTEPH significantly increases the risk of residual pulmonary hypertension in the early postoperative period of PEA (OR = 6.2 (1.90-10.27), P = .002), duration of hospital stay (OR = 1.1 (1.01-1.20), P = .020) and the risk of in-hospital mortality (OR = 4.4 (1.21-16.19), P = .023). The lung diffusion capacity revealed significant negative associations with the duration of hospital stay and in-hospital mortality (OR 0.87 (0.74-0.98), P = .012). CONCLUSION: COPD in patients with CTEPH significantly increases the risk of residual pulmonary hypertension, in-hospital mortality and increases the duration of hospital stay after PEA.

Chronic Lung Disease and Mortality after Cardiac Surgery: A Prospective Cohort Study.

OBJECTIVE: To investigate the 1-year survival in cardiac surgical patients with lung disease, including previously undiagnosed cases. DESIGN: Prospective cohort study. SETTING: Tertiary hospital. PARTICIPANTS: Patients scheduled for elective coronary artery bypass graft (CABG) surgery. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Pulmonary function tests (PFTs) were performed in 454 patients before surgery. Abnormal respiratory patterns were defined as follows: obstructive (forced expiratory volume in 1 second/forced vital capacity <0.70), restrictive (forced expiratory volume in 1 second/forced vital capacity ≥0.70 and forced vital capacity <80% of predicted), and mixed. Overall 1-year mortality was 3.3%. Among 31 patients with documented chronic obstructive pulmonary disease (COPD), mortality was 9.6%, hazard ratio (HR) 1.28, 95% confidence interval (CI) 1.02-12.80, p = 0.04. Of 423 patients without history of COPD, 57 obstructive, 46 restrictive, and 4 mixed abnormal patterns were identified. Of a total of 72 with obstructive lung disease confirmed by PFT (ie, 15 of COPD patients and 57 newly identified cases), 6.9% died, HR 2.75, 95% CI 0.98-8.07, p = 0.06. When combined with cases of COPD where a respiratory abnormality was confirmed (26 patients), newly diagnosed obstructive lung disease (57 patients) was significantly associated with 1-year mortality, HR 4.13, 95% CI 1.50-11.42, p = 0.006. The adjustment for EuroSCORE II did not change the results. CONCLUSIONS: Combination of confirmed preexisting lung disease and newly diagnosed cases provides a clear link to mid-term mortality.

Factors affecting the quality of life before and after surgery in patients with chronic thromboembolic pulmonary hypertension.

PURPOSE: To test the hypothesis that quality of life (QoL) parameters before surgery in patients with chronic thromboembolic pulmonary hypertension (CTEPH) are influenced by clinical determinants related to the underlying disease and to examine QoL parameters affected in the long-term after the operation by complications presenting in the early postoperative period. METHODS: This prospective cohort study included 128 patients who presented with CTEPH before and after pulmonary thromboendarterectomy (PTE; 1-year follow-up). All patients were examined regarding QoL using the Short-Form 36 Health Survey Questionnaire (SF-36). RESULTS: In patients with CTEPH, PTE provided immediate improvement in terms of pulmonary hemodynamic parameters and favorable effects on long-term outcome, including QoL 1 year after surgery. Multivariate analysis showed that systolic pulmonary arterial pressure, right ventricular ejection fraction, and the presence of coronary artery disease and chronic obstructive pulmonary disease (COPD) were independent factors affecting QoL on several SF-36 subscales in patients with CTEPH prior to surgery. The factors that affect patient QoL 1 year after surgery on some SF-36 subscales included the presence of coronary artery disease, COPD, heart failure, residual pulmonary hypertension, and prolonged ventilation, neurological complications in the early postoperative period of PTE. CONCLUSIONS: Surgical treatment for CTEPH leads to an increase in QoL in all SF-36 subscales, excluding general health perceptions. Factors affecting QoL in patients with CTEPH included severity of pulmonary arterial hypertension, comorbidity, and complications in the early postoperative period after PTE, such as heart failure, neurologic problems, residual pulmonary hypertension, and prolonged ventilation.

Prevalence and Implications of Abnormal Respiratory Patterns in Cardiac Surgery: A Prospective Cohort Study.

OBJECTIVE: To investigate the prevalence and impact of abnormal respiratory patterns in cardiac surgery patients. DESIGN: Prospective cohort study. SETTING: Tertiary hospital. PARTICIPANTS: Patients scheduled for elective coronary artery bypass graft surgery. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Pulmonary function tests were performed in 454 patients before surgery. Abnormal respiratory patterns were defined as follows: obstructive (forced expiratory volume in 1 s [FEV1]/forced vital capacity [FVC]<0.70), restrictive (FEV1/FVC≥0.70 and FVC<80% of predicted), and mixed (FEV1/FVC<0.70 and both FEV1 and FVC<80% of predicted). Of the 31 patients with a history of chronic obstructive pulmonary disease, no abnormal respiratory pattern was confirmed in 5. Of the 423 patients without a history of lung disease, the authors newly identified 57 obstructive, 46 restrictive, and 4 mixed patterns. Therefore, lung disease was reclassified in 24.7% of cases. Independent predictors of obstructive pattern were age, male sex, history of smoking, and chronic obstructive pulmonary disease. Obstructive lung disease was associated with 16 hours or longer ventilation. A reduced FEV1 was associated with a likelihood of atrial fibrillation (1-L decrement, odds ratio: 1.38, 95% confidence interval: 1.01-to-1.90, p = 0.04) and hospitalization time (regression coefficient: 1.23, 95% confidence interval: 0.54-to-1.91, p<0.001). CONCLUSIONS: Abnormal respiratory patterns are common and often underdiagnosed in the cardiac surgery setting. Pulmonary function tests help reveal patients at risk of complications and may provide an opportunity for intervention.

Brain Oxygen Supply Parameters in the Risk Assessment of Cerebral Complications During Carotid Endarterectomy.

OBJECTIVE: To determine whether preoperative regional cerebral oxygen saturation (rSO2) and the decrease in rSO2 during carotid clamping were predictive of the risk for neurologic complications in carotid endarterectomy and to determine the cutoff values of the studied parameters. DESIGN: Cohort, prospective, nonrandomized trial. SETTING: Research Institute of Circulation Pathology, Novosibirsk, Russia. PARTICIPANTS: The study comprised 466 adults who underwent carotid endarterectomy since 2012. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Patient characteristics, postoperative complications, and brain oxygen supply during carotid endarterectomy were analyzed. The primary endpoints were the perioperative and early postoperative neurologic complications. Ischemic stroke was diagnosed in 1.5% of patients, and cognitive disorders were reported in 2.6% of patients. Preoperative rSO2 of 50% was the cutoff value for the prediction of stroke outcome after carotid endarterectomy, with a sensitivity of 90.7% and specificity of 66.7%. A 20% decrease in rSO2 during temporary carotid clamping was the cutoff value for the prediction of stroke, with a sensitivity of 86.0% and specificity of 57.1%, and for the prediction of cognitive disorders, with a sensitivity of 88.1% and specificity of 58.3%. Preoperative rSO2 less than 50% and a decrease in rSO2 of at least 20% during temporary carotid artery clamping caused a significant increase in the hospitalization period. CONCLUSIONS: A 20% or more decrease in rSO2 during temporary internal carotid artery clamping during carotid endarterectomy caused a 10-fold increased risk of ischemic stroke and an 8-fold increased risk of cognitive disorders, whereas preoperative rSO2 less than 50% resulted in a 6-fold increased risk of ischemic stroke in the perioperative and early postoperative periods of carotid endarterectomy.