Summary
Personal protective equipment has become an important and emotive subject during the current coronavirus disease 2019 epidemic. Coronavirus disease 2019 is predominantly caused by contact or ...droplet transmission attributed to relatively large respiratory particles which are subject to gravitational forces and travel only approximately 1 metre from the patient. Airborne transmission may occur if patient respiratory activity or medical procedures generate respiratory aerosols. These aerosols contain particles that may travel much longer distances and remain airborne longer, but their infective potential is uncertain. Contact, droplet and airborne transmission are each relevant during airway manoeuvres in infected patients, particularly during tracheal intubation. Personal protective equipment is an important component, but only one part, of a system protecting staff and other patients from coronavirus disease 2019 cross‐infection. Appropriate use significantly reduces risk of viral transmission. Personal protective equipment should logically be matched to the potential mode of viral transmission occurring during patient care – contact, droplet or airborne. Recommendations from international organisations are broadly consistent, but equipment use is not. Only airborne precautions include a fitted high‐filtration mask, and this should be reserved for aerosol generating procedures. Uncertainty remains around certain details of personal protective equipment including use of hoods, mask type and the potential for re‐use of equipment.
This project was devised to estimate the incidence of major complications of airway management during anaesthesia in the UK and to study these events.
Reports of major airway management complications ...during anaesthesia (death, brain damage, emergency surgical airway, unanticipated intensive care unit admission) were collected from all National Health Service hospitals for 1 yr. An expert panel assessed inclusion criteria, outcome, and airway management. A matched concurrent census estimated a denominator of 2.9 million general anaesthetics annually.
Of 184 reports meeting inclusion criteria, 133 related to general anaesthesia: 46 events per million general anaesthetics 95% confidence interval (CI) 38–54 or one per 22 000 (95% CI 1 per 26–18 000). Anaesthesia events led to 16 deaths and three episodes of persistent brain damage: a mortality rate of 5.6 per million general anaesthetics (95% CI 2.8–8.3): one per 180 000 (95% CI 1 per 352–120 000). These estimates assume that all such cases were captured. Rates of death and brain damage for different airway devices (facemask, supraglottic airway, tracheal tube) varied little. Airway management was considered good in 19% of assessable anaesthesia cases. Elements of care were judged poor in three-quarters: in only three deaths was airway management considered exclusively good.
Although these data suggest the incidence of death and brain damage from airway management during general anaesthesia is low, statistical analysis of the distribution of reports suggests as few as 25% of relevant incidents may have been reported. It therefore provides an indication of the lower limit for incidence of such complications. The review of airway management indicates that in a majority of cases, there is ‘room for improvement’.
While the basic principles of conventional solar cells are well understood, little attention has gone towards maximizing the efficiency of photovoltaic devices based on shift currents. By analysing ...effective models, here we outline simple design principles for the optimization of shift currents for frequencies near the band gap. Our method allows us to express the band edge shift current in terms of a few model parameters and to show it depends explicitly on wavefunctions in addition to standard band structure. We use our approach to identify two classes of shift current photovoltaics, ferroelectric polymer films and single-layer orthorhombic monochalcogenides such as GeS, which display the largest band edge responsivities reported so far. Moreover, exploring the parameter space of the tight-binding models that describe them we find photoresponsivities that can exceed 100 mA W
. Our results illustrate the great potential of shift current photovoltaics to compete with conventional solar cells.
Summary
Despite being infrequent, complications of airway management remain an important contributor to morbidity and mortality during anaesthesia and care of the critically ill. Developments in the ...last three decades have made anaesthesia safer, and this has been mirrored in the equipment and techniques available for airway management. Modern technology including novel oxygenation modalities, widespread availability of capnography, second‐generation supraglottic airway devices and videolaryngoscopy provide the tools to make airway management safer still. However, technology will only take safety so far, and non‐technical aspects of airway management are critically important for communication and decision making during airway crises, acknowledging a ‘cannot intubate, cannot oxygenate’ situation and transitioning to emergency front of neck airway. Randomised controlled trials provide little useful information about safety in this setting, and data from registries and databases are likely to be of more value. This narrative review focuses on recent evidence in this area.
Augmented Renal Clearance Cook, Aaron M.; Hatton‐Kolpek, Jimmi
Pharmacotherapy,
March 2019, 2019-03-00, 20190301, Volume:
39, Issue:
3
Journal Article
Peer reviewed
Augmented renal clearance (ARC) is a phenomenon in critically ill patients characterized by increased creatinine clearance and elimination of renally eliminated medications. Patients with severe ...neurologic injury, sepsis, trauma, and burns have been consistently identified as at risk of ARC, with mean creatinine clearances ranging from 170 ml/minute to more than 300 ml/minute. Several potential mechanisms may contribute to the occurrence of ARC including endogenous responses to increased metabolism and solute production, alterations in neurohormonal balance, and therapeutic maneuvers such as fluid resuscitation. Augmented renal clearance is associated with suboptimal exposure to critical medications, including β‐lactams and vancomycin, increasing the risk of treatment failure. Although definitive screening tools are not yet known, critical care pharmacists must be vigilant in recognizing when ARC may be a contributing factor affecting expected treatment outcomes in individual patients. Optimizing dosing strategies in critically ill patients with ARC remains a goal of continued research. The current review discusses the clinical characteristics and methods of identifying patients at risk of ARC, potential mechanisms for ARC, and describes pharmacotherapy dosing considerations in patients with ARC.
New two-dimensional niobium and vanadium carbides have been synthesized by selective etching, at room temperature, of Al from Nb2AlC and V2AlC, respectively. These new matrials are promising ...electrode materials for Li-ion batteries, demonstrating good capability to handle high charge–discharge rates. Reversible capacities of 170 and 260 mA·h·g–1 at 1 C, and 110 and 125 mA·h·g–1 at 10 C were obtained for Nb2C and V2C-based electrodes, respectively.
Mycobacteria are a group of obligate aerobes that require oxygen for growth, but paradoxically have the ability to survive and metabolize under hypoxia. The mechanisms responsible for this metabolic ...plasticity are unknown. Here, we report on the adaptation of Mycobacterium smegmatis to slow growth rate and hypoxia using carbon-limited continuous culture. When M. smegmatis is switched from a 4.6 h to a 69 h doubling time at a constant oxygen saturation of 50%, the cells respond through the down regulation of respiratory chain components and the F1Fo-ATP synthase, consistent with the cells lower demand for energy at a reduced growth rate. This was paralleled by an up regulation of molecular machinery that allowed more efficient energy generation (i.e. Complex I) and the use of alternative electron donors (e.g. hydrogenases and primary dehydrogenases) to maintain the flow of reducing equivalents to the electron transport chain during conditions of severe energy limitation. A hydrogenase mutant showed a 40% reduction in growth yield highlighting the importance of this enzyme in adaptation to low energy supply. Slow growing cells at 50% oxygen saturation subjected to hypoxia (0.6% oxygen saturation) responded by switching on oxygen scavenging cytochrome bd, proton-translocating cytochrome bc1-aa3 supercomplex, another putative hydrogenase, and by substituting NAD+-dependent enzymes with ferredoxin-dependent enzymes thus highlighting a new pattern of mycobacterial adaptation to hypoxia. The expression of ferredoxins and a hydrogenase provides a potential conduit for disposing of and transferring electrons in the absence of exogenous electron acceptors. The use of ferredoxin-dependent enzymes would allow the cell to maintain a high carbon flux through its central carbon metabolism independent of the NAD+/NADH ratio. These data demonstrate the remarkable metabolic plasticity of the mycobacterial cell and provide a new framework for understanding their ability to survive under low energy conditions and hypoxia.
The Fourth National Audit Project of the Royal College of Anaesthetists and Difficult Airway Society (NAP4) was designed to identify and study serious airway complications occurring during ...anaesthesia, in intensive care unit (ICU) and the emergency department (ED).
Reports of major complications of airway management (death, brain damage, emergency surgical airway, unanticipated ICU admission, prolonged ICU stay) were collected from all National Health Service hospitals over a period of 1 yr. An expert panel reviewed inclusion criteria, outcome, and airway management.
A total of 184 events met inclusion criteria: 36 in ICU and 15 in the ED. In ICU, 61% of events led to death or persistent neurological injury, and 31% in the ED. Airway events in ICU and the ED were more likely than those during anaesthesia to occur out-of-hours, be managed by doctors with less anaesthetic experience and lead to permanent harm. Failure to use capnography contributed to 74% of cases of death or persistent neurological injury.
At least one in four major airway events in a hospital are likely to occur in ICU or the ED. The outcome of these events is particularly adverse. Analysis of the cases has identified repeated gaps in care that include: poor identification of at-risk patients, poor or incomplete planning, inadequate provision of skilled staff and equipment to manage these events successfully, delayed recognition of events, and failed rescue due to lack of or failure of interpretation of capnography. The project findings suggest avoidable deaths due to airway complications occur in ICU and the ED.
•Surface chemistry of MXenes characterized by XPS.•Studied the surface chemistry of the MXenes Ti3C2Tx, Ti2CTx, Ti3CNTx, Nb2CTx and Nb4C3Tx.•Freshly prepared and aged surfaces were compared.•Four ...surface moieties were confirmed, including O, OH and F, H2Oads.
In this work, a detailed high resolution X-ray photoelectron spectroscopy (XPS) analysis is presented for select MXenes—a recently discovered family of two-dimensional (2D) carbides and carbonitrides. Given their 2D nature, understanding their surface chemistry is paramount. Herein we identify and quantify the surface groups present before, and after, sputter-cleaning as well as freshly prepared vs. aged multi-layered cold pressed discs. The nominal compositions of the MXenes studied here are Ti3C2Tx, Ti2CTx, Ti3CNTx, Nb2CTx and Nb4C3Tx, where T represents surface groups that this work attempts to quantify. In all the cases, the presence of three surface terminations, O, OH and F, in addition to OH-terminations relatively strongly bonded to H2O molecules, was confirmed. From XPS peak fits, it was possible to establish the average sum of the negative charges of the terminations for the aforementioned MXenes. Based on this work, it is now possible to quantify the nature of the surface terminations. This information can, in turn, be used to better design and tailor these novel 2D materials for various applications.
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