7 research outputs found
Impact of Intermittent Operation on Lifetime and Performance of a PEM Water Electrolyzer
No full textThe aim of this study is to provide a better understanding of performance degrading mechanisms occurring when a proton exchange membrane water electrolyzer (PEM-WE) is coupled with renewable energies, where times of operation and idle periods alternate. An accelerated stress test (AST) is proposed, mimicking a fluctuating power supply by operating the electrolyzer cell between high (3 A cm(geo)(-2)) and low current densities (0.1 A cm(geo)(-2)), alternating with idle periods during which no current is supplied and the cell rests at open circuit voltage (OCV). Polarization curves, periodically recorded during the OCV-AST, reveal an initial increase in activity (approximate to 50 mV after 10 cycles) followed by a significant decrease in performance during prolonged OCV cycling due to an increasing high frequency resistance (HFR) (approximate to 1.6-fold after 718 cycles). These performance changes can clearly be related to the OCV periods, since they are not observed in a reference experiment where the OCV period is replaced by a potential hold at 1.3 V. The origin of the phenomena, which are responsible for the initial performance gain as well as the subsequent decay are analyzed via detailed electrochemical and physical characterization of the MEAs, and an operating strategy to prevent performance degradation is proposed. (c) The Author(s) 2019. Published by ECS.INEAmericas Int Meeting on Electrochemistry & Solid State Science (AiMES) / Joint Conf of 234th Meeting of The-Electrochemical-Society / 33rd Congress of Sociedad-Mexicana-de-Electroquimica (SMEQ) / 11th Meeting of the Mexico-Sect-of-the-Electrochem-Soc
Catalyst Aggregate Size Effect on the Mass Transport Properties of Non-Noble Metal Catalyst Layers for PEMFC Cathodes
No full textNon-noble metal catalysts (NNMCs) are regarded as a promising alternative to the costly Pt-based materials required to catalyze the oxygen reduction reaction (ORR) in proton exchange membrane fuel cell (PEMFC) cathodes. However, the large diversity of NNMC synthesis approaches reported in the literature results in materials featuring a wide variety of particle sizes and morphologies, and the effect of these properties on these catalysts' PEMFC performance remains poorly understood. To shed light on this matter, in this work we studied the physical and electrochemical properties of NNMC layers prepared from materials featuring broadly different aggregate sizes, whereby this property was tuned by ball milling the precursors used in the NNMCs' synthesis in the absence vs presence of a solvent. This led to two NNMCs featuring similar Fe-speciations and ORR-activities, but with vastly different aggregate sizes of >5 mu m vs approximate to 100 nm, respectively. Following the extensive characterization of catalyst layers (CLs) prepared with these materials via electron microscopy and X-ray tomography, PEMFC tests at different loadings unveiled that the smaller aggregate size and approximate to 20% higher porosity of the CL prepared from the wet-milled sample resulted in an improvement of its mass transport properties (as well as a approximate to 2-fold enhancement of its peak power density under H-2/air operation) over the dry-milled material. (c) 2023 The Author(s). Published on behalf of The Electrochemical Society by IOP Publishing Limited. This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 License (CC BY, http://creativecommons.org/licenses/by/4.0/),IN
Efficacy and adverse events profile of videolaryngoscopy in critically ill patients: subanalysis of the INTUBE study
No full textBackground: Tracheal intubation is a high-risk procedure in the critically ill, with increased intubation failure rates and a high risk of other adverse events. Videolaryngoscopy might improve intubation outcomes in this population, but evidence remains conflicting, and its impact on adverse event rates is debated.Methods: This is a subanalysis of a large international prospective cohort of critically ill patients (INTUBE Study) performed from 1 October 2018 to 31 July 2019 and involving 197 sites from 29 countries across five continents. Our primary aim was to determine the first-pass intubation success rates of videolaryngoscopy. Secondary aims were characterising (a) videolaryngoscopy use in the critically ill patient population and (b) the incidence of severe adverse effects compared with direct laryngoscopy.Results: Of 2916 patients, videolaryngoscopy was used in 500 patients (17.2%) and direct laryngoscopy in 2416 (82.8%). First-pass intubation success was higher with videolaryngoscopy compared with direct laryngoscopy (84% vs 79%, P1/40.02). Patients undergoing videolaryngoscopy had a higher frequency of difficult airway predictors (60% vs 40%, P<0.001). In adjusted analyses, videolaryngoscopy increased the probability of first-pass intubation success, with an OR of 1.40 (95% confidence interval [CI] 1.05-1.87). Videolaryngoscopy was not significantly associated with risk of major adverse events (odds ratio 1.24, 95% CI 0.95-1.62) or cardiovascular events (odds ratio 0.78, 95% CI 0.60-1.02).Conclusions: In critically ill patients, videolaryngoscopy was associated with higher first-pass intubation success rates, despite being used in a population at higher risk of difficult airway management. Videolaryngoscopy was not associated with overall risk of major adverse events
Intubation Practices and Adverse Peri-intubation Events in Critically Ill Patients from 29 Countries
No full textImportance: Tracheal intubation is one of the most commonly performed and high-risk interventions in critically ill patients. Limited information is available on adverse peri-intubation events. Objective: To evaluate the incidence and nature of adverse peri-intubation events and to assess current practice of intubation in critically ill patients. Design, Setting, and Participants: The International Observational Study to Understand the Impact and Best Practices of Airway Management in Critically Ill Patients (INTUBE) study was an international, multicenter, prospective cohort study involving consecutive critically ill patients undergoing tracheal intubation in the intensive care units (ICUs), emergency departments, and wards, from October 1, 2018, to July 31, 2019 (August 28, 2019, was the final follow-up) in a convenience sample of 197 sites from 29 countries across 5 continents. Exposures: Tracheal intubation. Main Outcomes and Measures: The primary outcome was the incidence of major adverse peri-intubation events defined as at least 1 of the following events occurring within 30 minutes from the start of the intubation procedure: cardiovascular instability (either: systolic pressure <65 mm Hg at least once, <90 mm Hg for >30 minutes, new or increase need of vasopressors or fluid bolus >15 mL/kg), severe hypoxemia (peripheral oxygen saturation <80%) or cardiac arrest. The secondary outcomes included intensive care unit mortality. Results: Of 3659 patients screened, 2964 (median age, 63 years; interquartile range [IQR], 49-74 years; 62.6% men) from 197 sites across 5 continents were included. The main reason for intubation was respiratory failure in 52.3% of patients, followed by neurological impairment in 30.5%, and cardiovascular instability in 9.4%. Primary outcome data were available for all patients. Among the study patients, 45.2% experienced at least 1 major adverse peri-intubation event. The predominant event was cardiovascular instability, observed in 42.6% of all patients undergoing emergency intubation, followed by severe hypoxemia (9.3%) and cardiac arrest (3.1%). Overall ICU mortality was 32.8%. Conclusions and Relevance: In this observational study of intubation practices in critically ill patients from a convenience sample of 197 sites across 29 countries, major adverse peri-intubation events - in particular cardiovascular instability - were observed frequently
Efficacy and adverse events profile of videolaryngoscopy in critically ill patients: subanalysis of the INTUBE study
No full textBackground: Tracheal intubation is a high-risk procedure in the critically ill, with increased intubation failure rates and a high risk of other adverse events. Videolaryngoscopy might improve intubation outcomes in this population, but evidence remains conflicting, and its impact on adverse event rates is debated. Methods: This is a subanalysis of a large international prospective cohort of critically ill patients (INTUBE Study) performed from 1 October 2018 to 31 July 2019 and involving 197 sites from 29 countries across five continents. Our primary aim was to determine the first-pass intubation success rates of videolaryngoscopy. Secondary aims were characterising (a) videolaryngoscopy use in the critically ill patient population and (b) the incidence of severe adverse effects compared with direct laryngoscopy. Results: Of 2916 patients, videolaryngoscopy was used in 500 patients (17.2%) and direct laryngoscopy in 2416 (82.8%). First-pass intubation success was higher with videolaryngoscopy compared with direct laryngoscopy (84% vs 79%, P=0.02). Patients undergoing videolaryngoscopy had a higher frequency of difficult airway predictors (60% vs 40%, P<0.001). In adjusted analyses, videolaryngoscopy increased the probability of first-pass intubation success, with an OR of 1.40 (95% confidence interval [CI] 1.05–1.87). Videolaryngoscopy was not significantly associated with risk of major adverse events (odds ratio 1.24, 95% CI 0.95–1.62) or cardiovascular events (odds ratio 0.78, 95% CI 0.60–1.02). Conclusions: In critically ill patients, videolaryngoscopy was associated with higher first-pass intubation success rates, despite being used in a population at higher risk of difficult airway management. Videolaryngoscopy was not associated with overall risk of major adverse events. Clinical trial registration: NCT03616054
Intubation Practices and Adverse Peri-intubation Events in Critically Ill Patients From 29 Countries
No full textKey PointsQuestionAmong critically ill patients undergoing tracheal intubation worldwide, how common are major adverse events during the peri-intubation period? FindingsIn this prospective observational study that included 2964 patients from 197 sites across 29 countries from October 2018 to July 2019, at least one major clinical event occurred after intubation in 45.2% of patients, including cardiovascular instability in 42.6%, severe hypoxemia in 9.3%, and cardiac arrest in 3.1%. MeaningAmong an international sample of critically ill patients undergoing tracheal intubation, major cardiopulmonary events occurred frequently.ImportanceTracheal intubation is one of the most commonly performed and high-risk interventions in critically ill patients. Limited information is available on adverse peri-intubation events. ObjectiveTo evaluate the incidence and nature of adverse peri-intubation events and to assess current practice of intubation in critically ill patients. Design, Setting, and ParticipantsThe International Observational Study to Understand the Impact and Best Practices of Airway Management in Critically Ill Patients (INTUBE) study was an international, multicenter, prospective cohort study involving consecutive critically ill patients undergoing tracheal intubation in the intensive care units (ICUs), emergency departments, and wards, from October 1, 2018, to July 31, 2019 (August 28, 2019, was the final follow-up) in a convenience sample of 197 sites from 29 countries across 5 continents. ExposuresTracheal intubation. Main Outcomes and MeasuresThe primary outcome was the incidence of major adverse peri-intubation events defined as at least 1 of the following events occurring within 30 minutes from the start of the intubation procedure: cardiovascular instability (either: systolic pressure <65 mm Hg at least once, <90 mm Hg for >30 minutes, new or increase need of vasopressors or fluid bolus >15 mL/kg), severe hypoxemia (peripheral oxygen saturation <80%) or cardiac arrest. The secondary outcomes included intensive care unit mortality. ResultsOf 3659 patients screened, 2964 (median age, 63 years; interquartile range [IQR], 49-74 years; 62.6% men) from 197 sites across 5 continents were included. The main reason for intubation was respiratory failure in 52.3% of patients, followed by neurological impairment in 30.5%, and cardiovascular instability in 9.4%. Primary outcome data were available for all patients. Among the study patients, 45.2% experienced at least 1 major adverse peri-intubation event. The predominant event was cardiovascular instability, observed in 42.6% of all patients undergoing emergency intubation, followed by severe hypoxemia (9.3%) and cardiac arrest (3.1%). Overall ICU mortality was 32.8%. Conclusions and RelevanceIn this observational study of intubation practices in critically ill patients from a convenience sample of 197 sites across 29 countries, major adverse peri-intubation events-in particular cardiovascular instability-were observed frequently.This international cohort study describes the incidence and nature of cardiovascular instability, severe hypoxemia, and cardiac arrest surrounding endotracheal intubation
Peri-intubation complications in critically ill obese patients: a secondary analysis of the international INTUBE cohort
No full textBackground: Airway management in critically ill obese patients is potentially associated with a higher risk of adverse events due to a constellation of physiological and anatomical challenges. Data from international prospective studies on peri-intubation adverse events in obese critically ill patients are lacking. Methods: INTUBE (International Observational Study to Understand the Impact and Best Practices of Airway Management In Critically Ill Patients) was an international multicentre prospective cohort study enrolling critically ill adult patients undergoing in-hospital tracheal intubation in 197 sites from 29 countries worldwide from October 1, 2018, to July 31, 2019. This secondary analysis compares airway management practices and outcomes between obese (body mass index–BMI ≥ 30 kg/m2) and non-obese patients (BMI < 30 kg/m2). Results: A total of 2946 patients met inclusion criteria for this secondary analysis, 639 (21.7%) obese and 2307 (78.3%) non-obese. Severe peri-intubation hypoxemia was more frequently reported in obese compared to non-obese patients (12.1% vs 8.6% respectively, p = 0.01). Variables independently associated with a higher risk of peri-intubation hypoxemia were baseline SpO2/FiO2 (OR 0.996, 95% CI 0.994–0.997), 30–45° head-up position (OR 1.53, 95% CI 1.04–2.26) and first-pass intubation failure (OR for first-pass success 0.21, 95% CI 0.15–0.29). Obesity (OR 0.71, 95% CI 0.56–0.91) and 20° head-up position (OR 0.67, 95% CI 0.47–0.95) were independently associated with higher likelihood of first-pass intubation failure. In contrast, intubation by staff physician/consultant (OR 1.70, 95% CI 1.30–2.21) or anesthesiologists (OR 1.98, 95% CI 1.55–2.53) were associated with higher first-pass success. Conclusions: Compared to non-obese patients, obese critically ill exhibit a higher incidence of peri-intubation severe hypoxemia. In this population, worse baseline oxygenation and first-pass intubation failure significantly increase the risk of peri-intubation severe hypoxemia. As obesity is linked to a higher likelihood of first-pass intubation failure, likely driven by more challenging airway features, in this high-risk population first attempt should be performed by an expert operator to minimize peri-intubation complications. Trial registration: Clinicaltrials.gov NCT03616054. Registered 3 August 2018
