Background
- COVID-19 has led to over 1 million deaths worldwide and has been associated with cardiac complications including cardiac arrhythmias. The incidence and pathophysiology of these manifestations remain elusive. In this worldwide survey of patients hospitalized with COVID-19 who developed cardiac arrhythmias, we describe clinical characteristics associated with various arrhythmias, as well as global differences in modulations of routine electrophysiology practice during the pandemic.
Methods
- We conducted a retrospective analysis of patients hospitalized with COVID-19 infection worldwide with and without incident cardiac arrhythmias. Patients with documented atrial fibrillation (AF), atrial flutter (AFL), supraventricular tachycardia (SVT), non-sustained or sustained ventricular tachycardia (VT), ventricular fibrillation (VF), atrioventricular block (AVB), or marked sinus bradycardia (HR<40bpm) were classified as having arrhythmia. De-identified data was provided by each institution and analyzed.
Results
- Data was collected for 4,526 patients across 4 continents and 12 countries, 827 of whom had an arrhythmia. Cardiac comorbidities were common in patients with arrhythmia: 69% had hypertension, 42% diabetes mellitus, 30% had heart failure and 24% coronary artery disease. Most had no prior history of arrhythmia. Of those who did develop an arrhythmia, the majority (81.8%) developed atrial arrhythmias, 20.7% developed ventricular arrhythmias, and 22.6% had bradyarrhythmia. Regional differences suggested a lower incidence of AF in Asia compared to other continents (34% vs. 63%). Most patients in in North America and Europe received hydroxychloroquine, though the frequency of hydroxychloroquine therapy was constant across arrhythmia types. Forty-three percent of patients who developed arrhythmia were mechanically ventilated and 51% survived to hospital discharge. Many institutions reported drastic decreases in electrophysiology procedures performed.
Conclusions
- Cardiac arrhythmias are common and associated with high morbidity and mortality among patients hospitalized with COVID-19 infection. There were significant regional variations in the types of arrhythmias and treatment approaches.
The understanding of the chemical nature of the oil is important for both the optimization of the process and the design of upgrading strategies for further use as an energy carrier or toward transportation fuels. Hydrothermal treatment (HTT) oil is a complex matrix, whose composition is strongly affected by the feedstock type and by the HTT experimental conditions. In the present work, HTT oil from Desmodesmus sp. was subjected to a detailed chemical analysis. Various characterization techniques (silica gel chromatography, methanolysis, size exclusion chromatography, analytical pyrolysis, elemental analysis, and thermogravimetric techniques) were coupled to gather clearer information on the chemical nature of HTT oil obtained at different reaction times, temperatures, and slurry concentrations. Special attention was paid to the fate of N in the HTT process and the nature of the N-containing species in the oil. By cross-checking results from the chemical characterization of the oil with process data, it was finally possible to identify some different competitive reactions involved in the formation of HTT oil at different conditions. Results show that main compounds obtained at low temperature are still classifiable as lipids, which are extractable without the HTT, together with some short chain algaenan and some hydrophobic protein fragments that end up in the organic solvent phase. At higher temperature (300–375 °C), proteins and cellulose started to break down, giving cyclic dipeptides and amino acids side chains (by pyrolysis-like reactions), carbohydrates derivatives (e.g., furans) and products from the cross reaction of proteins and carbohydrates (e.g., formation of alkyl-pyrrolidinones, pyrazines, pyrroles and melanoidin-like materials). This phenomenon is responsible for the observed increase in oil mass yield with increasing processing temperature, as well as the increase in nitrogen content of the oil. Optimization of the production of fuels and fuel precursors by HTT should be done in conjunction with evaluation of downstream processing options and/or the possibility to recycle unconverted material to the algae cultivation.
The hydrothermal treatment (HTT) technology is evaluated for its potential as a process to convert algae and algal debris into a liquid fuel, within a sustainable algae biorefinery concept in which, next to fuels (gaseous and liquid), high value products are coproduced, nutrients and water are recycled, and the use of fossil energy is minimized. In this work, the freshwater microalgae Desmodesmus sp. was used as feedstock. HTT was investigated over a very wide range of temperatures (175–450 °C) and reaction times (up to 60 min), using a batch reactor system. The different product phases were quantified and analyzed. The maximum oil yield (49 wt %) was obtained at 375 °C and 5 min reaction time, recovering 75% of the algal calorific value into the oil and an energy densification from 22 to 36 MJ/kg. At increasing temperature, both the oil yield and the nitrogen content in the oil increased, necessitating further investigation on the molecular composition of the oil. This was performed in the adjacent collaborative paper with special attention to the nitrogen-containing compounds and to gain insight in the liquefaction mechanism. A pioneering visual inspection of the cells after HTT showed that a large step increase in the HTT oil yield, when going from 225 to 250 °C at 5 min reaction time, coincided with a major cell wall rupture under these conditions. Additionally, it was found that the oil composition, by extractive recovery after HTT below 250 °C, did change with temperature, even though the algal cells were visually still unbroken. Finally, the possibilities of recycling growth nutrients became evident by analyzing the aqueous fractions obtained after HTT. From the results obtained, we concluded that HTT is most suited as post-treatment technology in an algae biorefinery system, after the wet extraction of high value products, such as protein-rich food/feed ingredients and lipids.
Three biochars were prepared by intermediate pyrolysis from poultry litter at different temperatures (400, 500, and 600 °C with decreasing residence times) and compared with biochars from corn stalk prepared under the same pyrolysis conditions. The phytotoxicity of these biochars was estimated by means of seed germination tests on cress (Lepidium sativum L.) conducted in water suspensions (at 2, 5, and 40 g/L) and on biochars wetted according to their water-holding capacity. Whereas the seeds germinated after 72 h in water suspensions with corn stalk biochar were similar to the control (water only), significant inhibition was observed with poultry litter biochars. In comparison to corn stalk, poultry litter generated biochars with higher contents of ash, ammonium, nitrogen, and volatile fatty acids (VFAs) and a similar concentration of polycyclic aromatic hydrocarbons (PAHs). Results from analytical pyrolysis (Py-GC-MS) indicated that nitrogen-containing organic compounds (NCCs) and aliphatic components were distinctive constituents of the thermally labile fraction of poultry litter biochar. The inhibition of germination due to poultry litter biochar produced at 400 °C (PL400) was suppressed after solvent extraction or treatment with active sludge. A novel method based on solid-phase microextraction (SPME) enabled the identification of mobile organic compounds in PL400 capable of being released in air and water, including VFAs and NCCs. The higher phytotoxicity of poultry litter than corn biochars was tentatively attributed to hydrophilic biodegradable substances derived from lipids or proteins removable by water leaching or microbial treatments.
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