Spectroscopic investigation of a Co(0001) model catalyst during exposure to H2 and CO at near-ambient pressures.

Cobalt catalysts, although already used industrially for Fischer-Tropsch synthesis, are prone to a number of deactivation mechanisms such as oxidation of the active phase, and the deposition of carbon and reaction products. We have performed near-ambient-pressure X-ray photoelectron spectroscopy on Co(0001) model catalysts during exposure to gases relevant to Fischer-Tropsch synthesis, i.e., CO and H2, at 0.25 mbar total pressure. At this pressure, CO seems to be more efficient at keeping the Co(0001) surface metallic than H2, which is the opposite behavior as reported in the literature for other pressure ranges. We offer an interpretation of these differences based on the preferred adsorption and dissociation sites of CO and H2 compared to the oxidizing agent water (present as impurity in the gas feed and one of the products of the reaction). Additionally, detailed carbon spectra measured at the HIPPIE beamline of MAX IV allow for the distinction of different adsorbed species: CO and COx species are present in correlation to the presence of oxygen on the surface. Carbidic carbon and graphitic carbon can both be removed by hydrogen, whereas adsorbed hydrocarbons possibly poison the surface.

Anesthetic Implications in Managing a Case of Primary Hyperaldosteronism: A Case Report.

Primary hyperaldosteronism (also called Conn's syndrome) is a rare condition of the adrenal glands characterized by excessive secretion of the hormone aldosterone, which regulates the balance of water and electrolytes in the body, and maintains blood volume and pressure. Hyperaldosteronism causes sodium and water retention, hypokalemia, hypertension, and muscle weakness. Common cause of primary hyperaldosteronism is an adrenal adenoma or bilateral adrenal hyperplasia. A 36-year-old female presented with hypertension, hypokalemia and muscle cramps, and on further evaluation by computed tomography (CT) scan was found to have a right adrenal adenoma. She was scheduled for a right-sided laparoscopic adrenalectomy. We report the successful peri-operative anesthetic management of this patient who had an uneventful intra-operative and post-operative course.

Current Anesthetic Care of Patients Undergoing Transcatheter Aortic Valve Replacement in Europe: Results of an Online Survey.

OBJECTIVES: Transcatheter aortic valve replacement (TAVR) has become an alternative treatment for patients with symptomatic aortic stenosis not eligible for surgical valve replacement due to a high periprocedural risk or comorbidities. However, there are several areas of debate concerning the pre-, intra- and post-procedural management. The standards and management for these topics may vary widely among different institutions and countries in Europe. DESIGN: Structured web-based, anonymized, voluntary survey. SETTING: Distribution of the survey via email among members of the European Association of Cardiothoracic Anaesthesiology working in European centers performing TAVR between September and December 2018. PARTICIPANTS: Physicians. MEASUREMENTS AND MAIN RESULTS: The survey consisted of 25 questions, including inquiries regarding number of TAVR procedures, technical aspects of TAVR, medical specialities present, preoperative evaluation of TAVR candidates, anesthesia regimen, as well as postoperative management. Seventy members participated in the survey. Reporting members mostly performed 151-to-300 TAVR procedures per year. In 90% of the responses, a cardiologist, cardiac surgeon, cardiothoracic anesthesiologist, and perfusionist always were available. Sixty-six percent of the members had a national curriculum for cardiothoracic anesthesia. Among 60% of responders, the decision for TAVR was made preoperatively by an interdisciplinary heart team with a cardiothoracic anesthesiologist, yet in 5 countries an anesthesiologist was not part of the decision-making. General anesthesia was employed in 40% of the responses, monitored anesthesia care in 44%, local anesthesia in 23%, and in 49% all techniques were offered to the patients. In cases of general anesthesia, endotracheal intubation almost always was performed (91%). It was stated that norepinephrine was the vasopressor of choice (63% of centers). Transesophageal echocardiography guiding, whether performed by an anesthesiologist or cardiologist, was used only ≤30%. Postprocedurally, patients were transferred to an intensive care unit by 51.43% of the respondents with a reported nurse-to-patient ratio of 1:2 or 1:3, to a post-anesthesia care unit by 27.14%, to a postoperative recovery room by 11.43%, and to a peripheral ward by 10%. CONCLUSION: The results indicated that requirements and quality indicators (eg, periprocedural anesthetic management, involvement of the anesthesiologist in the heart team, etc) for TAVR procedures as published within the European guideline are largely, yet still not fully implemented in daily routine. In addition, anesthetic TAVR management also is performed heterogeneously throughout Europe.

Structural Characterization of a Novel Two-Dimensional Material: Cobalt Sulfide Sheets on Au(111).

Transition metal dichalcogenides (TMDCs) are a type of two-dimensional (2D) material that has been widely investigated by both experimentalists and theoreticians because of their unique properties. In the case of cobalt sulfide, density functional theory (DFT) calculations on free-standing S-Co-S sheets suggest there are no stable 2D cobalt sulfide polymorphs, whereas experimental observations clearly show TMDC-like structures on Au(111). In this study, we resolve this disagreement by using a combination of experimental techniques and DFT calculations, considering the substrate explicitly. We find a 2D CoS(0001)-like sheet on Au(111) that delivers excellent agreement between theory and experiment. Uniquely this sheet exhibits a metallic character, contrary to most TMDCs, and exists due to the stabilizing interactions with the Au(111) substrate.

Mitochondrial Haplogroup and the Risk of Acute Kidney Injury Following Cardiac Bypass Surgery.

Although mitochondrial dysfunction plays a key role in the pathophysiology of acute kidney injury (AKI), the influence of mitochondrial genetic variability in this process remains unclear. We explored the association between the risk of post-cardiac bypass AKI and mitochondrial haplotype - inherited mitochondrial genomic variations of potentially functional significance. Our single-centre study recruited consecutive patients prior to surgery. Exclusions included stage 5 CKD, non-Caucasian race and subsequent off-pump surgery. Haplogroup analysis allowed characterisation of the study population using the common mutations and by phylogenetic supergroup (WXI and HV). Chi-square tests for association allowed the identification of potential predictors of AKI for use in logistic regression analysis. AKI occurred in 12.8% of the study population (n = 881; male 69.6%, non-diabetic 78.5%, median (interquartile range) age 68.0 (61.0-75.0) years). The haplogroup profile comprised H (42.7%), J (12.1%), T (10.9%), U (14.4%) and K (7.6%). Although the regression model was statistically significant (χ2 = 95.483, p < 0.0005), neither the phylogenetic supergroups nor any individual haplogroup was a significant contributor. We found no significant association between common European haplogroups and the risk of post-cardiac bypass AKI. However, given the major role of mitochondrial dysfunction in AKI, there is a need to replicate our findings in other cohorts and with other aetiologies of AKI.

Pre-anaesthetic evaluation of the patient with end-stage lung disease.

Lung transplantation is a viable alternative for end-stage lung diseases, which offers good quality of life and survival outcomes for recipients. The aims of pre-assessment for potential lung transplant recipients are to assess fitness for surgery, optimise co-morbidities, commence interventions or investigations, weigh risk-benefit ratio, plan appropriate analgesia and obtain informed consent. The assessment information is gathered from the medical record, patient interview, physical examination and pre-operative tests. A comprehensive workup includes cardiopulmonary evaluation, haematological, biochemical, microbiological and immunological investigations. Most of the evidence regarding lung transplantation is gleaned from retrospective data from single, multi-centre or multinational registries. The lack of good quality evidence means that the guidelines are based on expert consensus.

Evidence of cardiac functional reserve upon exhaustion during incremental exercise to determine VO2max.

BACKGROUND: There remains considerable debate regarding the limiting factor(s) for maximal oxygen uptake (VO2max). Previous studies have shown that the central circulation may be the primary limiting factor for VO2max and that cardiac work increases beyond VO2max. AIM: We sought to evaluate whether the work of the heart limits VO2max during upright incremental cycle exercise to exhaustion. METHODS: Eight trained men completed two incremental exercise trials, each terminating with exercise at two different rates of work eliciting VO2max (MAX and SUPRAMAX). During each exercise trial we continuously recorded cardiac output using pulse-contour analysis calibrated with a lithium dilution method. Intra-arterial pressure was recorded from the radial artery while pulmonary gas exchange was measured continuously for an assessment of oxygen uptake. RESULTS: The workload during SUPRAMAX (mean±SD: 346.5±43.2 W) was 10% greater than that achieved during MAX (315±39.3 W). There was no significant difference between MAX and SUPRAMAX for Q (28.7 vs 29.4 L/min) or VO2 (4.3 vs 4.3 L/min). Mean arterial pressure was significantly higher during SUPRAMAX, corresponding to a higher cardiac power output (8.1 vs 8.5 W; p<0.06). CONCLUSIONS: Despite similar VO2 and Q, the greater cardiac work during SUPRAMAX supports the view that the heart is working submaximally at exhaustion during an incremental exercise test (MAX).

The effect of ex vivo lung perfusion on microbial load in human donor lungs.

BACKGROUND: Ex vivo lung perfusion (EVLP) has emerged as a technique to potentially recondition unusable donor lungs for transplantation. Beneficial effects of EVLP on physiologic function have been reported, but little is known about the effect of normothermic perfusion on the infectious burden of the donor lung. In this study, we investigated the effect of EVLP on the microbial load of human donor lungs. METHODS: Lungs from 18 human donors considered unusable for transplantation underwent EVLP with a perfusate containing high-dose, empirical, broad-spectrum anti-microbial agents. Quantitative cultures of bacteria and fungi were performed on bronchoalveolar lavage fluid from the donor lung before and after 3 to 6 hours of perfusion. The identification of any organisms and changes in number of colony forming units before and after EVLP were assessed and anti-microbial susceptibilities identified. RESULTS: Thirteen out of 18 lungs had positive cultures, with bacterial loads significantly decreasing after EVLP. Yeast loads increased when no anti-fungal treatment was given, but were reduced when prophylactic anti-fungal treatment was added to the circuit. Six lungs were ultimately transplanted into patients, all of whom survived to hospital discharge. There was 1 death at 11 months. CONCLUSIONS: Our study shows that EVLP with high-dose, empirical anti-microbial agents in the perfusate is associated with an effective reduction in the microbial burden of the donor lung, a benefit that has not previously been demonstrated.

Management issues during HeartWare left ventricular assist device implantation and the role of transesophageal echocardiography.

Left ventricular assist devices (LVAD) are increasingly used for mechanical circulatory support of patients with severe heart failure, primarily as a bridge to heart transplantation. Transesophageal echocardiography (TEE) plays a major role in the clinical decision making during insertion of the devices and in the post-operative management of these patients. The detection of structural and device-related mechanical abnormalities is critical for optimal functioning of assist device. In this review article, we describe the usefulness of TEE for optimal perioperative management of patients presenting for HeartWare LVAD insertion.

Isolated complete cleft.

Cleft sternum is a rare congenital anomaly due to failure of fusion of the sternal bone. The etiology of this defect is not well understood. The anomaly is more common in females and may be associated with Cantrell's pentalogy. It can be partial or complete. An 8-year-old female child presented with complete defect in the sternum which was confirmed with a chest radiograph and computed tomography. Only 24 cases of isolated complete cleft sternum have been reported so far. The treatment ranges from primary closure of the defect to the use of various autologous and prosthetic grafts. Our patient was treated with primary closure of the defect.

Measurement of cardiac output during exercise in healthy, trained humans using lithium dilution and pulse contour analysis.

The aim of this study was to evaluate the use of pulse contour analysis calibrated with lithium dilution in a single device (LiDCO) for measurement of cardiac output (Q) during exercise in healthy volunteers. We sought to; (a) compare pulse contour analysis (PulseCO) and lithium indicator dilution (LiDCO) for the measurement of Q during exercise, and (b) assess the requirement for recalibration of PulseCO with LiDCO during exercise. Ten trained males performed multi-stage cycling exercise at intensities below and above ventilatory threshold before constant load maximal exercise to exhaustion. Uncalibrated PulseCO Q (Qraw) was compared to that calibrated with lithium dilution at baseline Qbaseline, during submaximal exercise below (Qlow) and above (Qhigh) ventilatory threshold, and at each exercise stage individually (Qexercise). There was a significant difference between Qbaseline and all other calibration methods during exercise, but not at rest. No significant differences were observed between other methods. Closest agreement with Qexercise was observed for Qhigh (bias ± limits of agreement: 4.8 ± 30.0%). The difference between Qexercise and both Qlow and Qraw was characterized by low bias (4-7%) and wide limits of agreement (> ± 40%). Calibration of pulse contour analysis with lithium dilution prior to exercise leads to a systematic overestimation of exercising cardiac output. A single calibration performed during exercise above the ventilatory threshold provided acceptable limits of agreement with an approach incorporating multiple calibrations throughout exercise. Pulse contour analysis may be used for Q measurement during exercise providing the system is calibrated during exercise.

Transesophageal echocardiography: instrumentation and system controls.

Transesophageal echocardiography (TEE) is a semi-invasive, monitoring and diagnostic tool, which is used in the perioperative management of cardiac surgical and hemodynamically unstable patients. The low degree of invasiveness and the capacity to visualize and assimilate dynamic information that can change the course of the patient management is an important advantage of TEE. Although TEE is reliable, comprehensive, credible, and cost-effective, it must be performed by a trained echocardiographer who understands the indications and the potential complications of the procedure, and has the ability to achieve proper acquisition and interpretation of the echocardiographic data. Adequate knowledge of the physics of ultrasound and the TEE machine controls is imperative to optimize image quality, reduce artifacts, and prevent misinterpretation of diagnosis. Two-dimensional (2D) and Motion (M) mode imaging are used for obtaining anatomical information, while Doppler and Color Flow imaging are used for information on blood flow. 3D technology enables us to view the cardiac structures from different perspectives. Despite the recent advances of 3D TEE, a sharp, optimized 2D image is pivotal for the reconstruction. This article describes the relevant underlying physical principles of ultrasound and focuses on a systematic approach to instrumentation and use of controls in the practical use of transesophageal echocardiography.

Are surrogate assumptions and use of diuretics associated with diagnosis and staging of acute kidney injury after cardiac surgery?

BACKGROUND AND OBJECTIVES: This study measured the association between the Acute Kidney Injury Network (AKIN) diagnostic and staging criteria and surrogates for baseline serum creatinine (SCr) and body weight, compared urine output (UO) with SCr criteria, and assessed the relationships between use of diuretics and calibration between criteria and prediction of outcomes. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: This was a retrospective cohort study using prospective measurements of SCr, hourly UO, body weight, and drug administration records from 5701 patients admitted, after cardiac surgery, to a cardiac intensive care unit between 1995 and 2006. RESULTS: More patients (n=2424, 42.5%) met SCr diagnostic criteria with calculated SCr assuming a baseline estimated GFR of 75 ml/min per 1.73 m(2) than with known baseline SCr (n=1043, 18.3%). Fewer patients (n=484, 8.5%) met UO diagnostic criteria with assumed body weight (70 kg) than with known weight (n=624, 10.9%). Agreement between SCr and UO criteria was fair (κ=0.28; 95% confidence interval 0.25-0.31). UO diagnostic criteria were specific (0.95; 0.94-0.95) but insensitive (0.36; 0.33-0.39) compared with SCr. Intravenous diuretics were associated with higher probability of falling below the UO diagnostic threshold compared with SCr, higher 30-day mortality (relative risk, 2.27; 1.08-4.76), and the need for renal support (4.35; 1.82-10.4) compared with no diuretics. CONCLUSIONS: Common surrogates for baseline estimated GFR and body weight were associated with misclassification of AKIN stage. UO criteria were insensitive compared with SCr. Intravenous diuretic use further reduced agreement and confounded association between AKIN stage and 30-day mortality or need for renal support.

Trans-esophageal echocardiography for tricuspid and pulmonary valves.

Transesophageal echocardiography has been shown to provide unique information about cardiac anatomy, function, hemodynamics and blood flow and is relatively easy to perform with a low risk of complications. Echocardiographic evaluation of the tricuspid and pulmonary valves can be achieved with two-dimensional and Doppler imaging. Transesophageal echocardiography of these valves is more challenging because of their complex structure and their relative distance from the esophagus. Two-dimensional echocardiography allows an accurate visualization of the cardiac chambers and valves and their motion during the cardiac cycle. Doppler echocardiography is the most commonly used diagnostic technique for detecting and evaluating valvular regurgitation. The lack of good quality evidence makes it difficult to recommend a validated quantitative approach but expert consensus recommends a clinically useful qualitative approach. This review ennumerates probe placement, recommended cross-sectional views, flow patterns, quantitative equations including the clinical approach to the noninvasive quantification of both stenotic and regurgitant lesions.

A microbiological survey of bicarbonate-based replacement circuits in continuous veno-venous hemofiltration.

OBJECTIVE: The potential for clinically significant transfer of pyrogen-inducing material in dialysate and substitution fluids is well recognized in the setting of chronic hemodialysis and hemodiafiltration and has led to the establishment of strict standards for microbiological purity. Preliminary evidence has indicated the potential for fluid contamination in continuous renal replacement therapy, and although the scale of the problem in contemporary, industry-standard equipment is unclear. We aimed to define the microbial integrity of modern continuous veno-venous hemofiltration (CVVH) replacement fluid circuitry. DESIGN: Twenty-four CVVH replacement fluid circuits (mean lifespan, 34.2 hours; range, 4-86) were studied at completion of therapy. SETTING: The integrated critical care unit and cardiothoracic intensive care unit of the Freeman Hospital, Newcastle upon Tyne, United Kingdom, between January and August 2007. SUBJECTS: Patients with renal failure receiving treatment with CVVH. INTERVENTIONS: Nil. MEASUREMENTS: Culture and endotoxin assays of replacement fluid, culture of endoluminal swabs, and electron microscopy of harvested tubing. MAIN RESULTS: Of the 24 replacement fluid cultures, nine (mean lifespan 32.8 hours, range 5-79) breached European Pharmacopoeia standards for ultrapure water (<0.1 colony-forming units/mL). One of 24 endotoxin measurements breached European Pharmacopoeia standards (<0.03 endotoxin units/mL). Internal tubing cultures were negative, but electron microscopy revealed 13 of the 24 collected tubing samples to be contaminated with biofilm. Only seven of the 24 studied circuits proved to be free from microbial contamination. CONCLUSIONS: We have confirmed frequent breaches of microbial integrity in industry-standard, bicarbonate-based CVVH, indicating the potential for added risk to the vulnerable, critically ill patient. These findings are of particular concern given the need for systemic infusion of replacement fluid. Measures to reduce the levels of contamination and their impact are discussed.

Inhaled nitric oxide for modulation of ischemia-reperfusion injury in lung transplantation.

BACKGROUND: The prophylactic administration of inhaled nitric oxide (NO) during reperfusion after lung transplantation has been shown to reduce neutrophil-induced injury in animal models. There remain questions regarding efficacy in the clinical setting and concerns regarding increased free radical injury. We sought to assess the efficacy of NO in reducing neutrophil infiltration and associated injury if administered from the very onset of reperfusion in clinical lung transplantation. METHODS: Twenty bilateral sequential lung transplant recipients were randomized to receive 20-ppm inhaled NO (NO group) or a standard anesthetic gas mixture (control group) from the onset of ventilation. Bronchoalveolar lavage was performed immediately prior to implantation and after 30 minutes of reperfusion and analyzed for inflammatory cytokine levels and free radical surrogates. Primary graft dysfunction (PGD) scoring was performed prospectively for 72 hours post-transplant. RESULTS: The prophylactic administration of NO during the first 30 minutes of reperfusion had no statistically significant effect on the development of Grade II to III PGD (5 of 10 in NO group and 7 of 10 in control group, p = 0.36) or gas exchange (area under the curve: 429 +/- 296 vs 336 +/- 306; p = 0.64) in the NO and control groups, respectively. Pulmonary neutrophil sequestration, as measured by the transpulmonary arteriovenous neutrophil difference, was not influenced by the administration of NO. Prophylactic NO did not significantly alter the concentration of interleukin-8, myeloperoxidase or nitrotyrosine during transplantation. CONCLUSIONS: This study could not demonstrate a significant effect of inhaled NO during the first 30 minutes of reperfusion in the prevention of neutrophil injury and primary graft dysfunction after lung transplantation.

An unusual complication of intranasal antrostomi.

Intranasal antrostomies are performed for treating maxillary simusitis. Here we present a rare case, who developed maxillary simusitis as a complication of the previous inferior meatal intranasal antrostomy. This case also proves the current concept that even though the inferior meatal antrostomy opening may be patent, the drainage is through the natural ostium.