Pt+(C2H2)n Complexes Studied with Selected-Ion Infrared Spectroscopy.

Platinum cation complexes with multiple acetylene molecules are studied with mass spectrometry and infrared laser spectroscopy. Complexes of the form Pt+(C2H2)n are produced in a molecular beam by laser vaporization, analyzed with a time-of-flight mass spectrometer, and selected by mass for studies of their vibrational spectroscopy. Photodissociation action spectra in the C-H stretching region are compared to the spectra predicted for different structural isomers using density functional theory. The comparison between experiment and theory demonstrates that platinum forms cation-π complexes with up to three acetylene molecules, producing an unanticipated asymmetric structure for the three-ligand complex. Additional acetylenes form solvation structures around this three-ligand core. Reacted structures that couple acetylene molecules (e.g., to form benzene) are found by theory to be energetically favorable, but their formation is inhibited under the conditions of these experiments by large activation barriers.

Cation Complexes of Uranium and Thorium with Cyclooctatetraene: Photochemistry and Decomposition Products.

Ion-molecule complexes of uranium or thorium singly-charged positive ions bound to cyclooctatetraene (COT), i.e., M+(COT)1,2, are produced by laser ablation and studied with UV laser photodissociation. The ions are selected by mass and excited at 355 or 532 nm, and the ionized dissociation products are detected using a reflectron time-of-flight mass spectrometer. The abundant fragments M+(C6H6), M+(C4H4), and M+(C2H2) occur for complexes of both metals, whereas the M+(C4H2), M+(C3H3), and M+(C5H5) fragments are prominent for uranium complexes but not for thorium. Additional experiments investigate the dissociation of M+(benzene)1,2 ions which may be intermediates in the fragmentation of the COT ions. The experiments are complemented by computational quantum chemistry to investigate the structures and energetics of fragment ions. Various cation-π and metallacycle structures are indicated for different fragment ions. The metal ion-ligand bond energies for corresponding complex ions are systematically greater for the thorium species. The computed thermochemistry makes it possible to explain the mechanistic details of the photochemical fragmentation processes and to reveal new actinide organometallic structures.

Coordination and Spin States in Fe+(C2H2)n Complexes Studied with Selected-Ion Infrared Spectroscopy.

Fe+(acetylene)n ion-molecule complexes are produced in a supersonic molecular beam with pulsed laser vaporization. These ions are mass selected and studied with infrared photodissociation spectroscopy in the C-H stretching region, complemented by computational chemistry calculations. All C-H stretch vibrations are shifted to frequencies lower than the vibrations of isolated acetylene because of the charge transfer that occurs between the metal ion and the molecules. Complexes in the size range of n = 1-4 are found to have structures with individual acetylene molecules bound to the core metal ion via cation-π interactions. The coordination is completed with four ligands in a structure close to a distorted tetrahedron. Larger complexes in the range of n = 5-8 have external acetylene molecules solvating this n = 4 core ion via CH-π bonding to inner-shell ligands. DFT computations predict that quartet spin states are more stable for all complex sizes, but infrared spectra for quartet and doublet spin states are quite similar, precluding definitive determination of the spin states. There is no evidence for any of these complexes having acetylenes coupled into reacted structures. This is consistent with computed thermochemistry, which finds significant activation barriers to such reactions.

Utilisation of tracheostomy in patients with COVID-19 in England: Patient characteristics, timing and outcomes.

OBJECTIVES: We aimed to characterise the use of tracheostomy procedures for all COVID-19 critical care patients in England and to understand how patient factors and timing of tracheostomy affected outcomes. DESIGN: A retrospective observational study using exploratory analysis of hospital administrative data. SETTING: All 500 National Health Service hospitals in England. PARTICIPANTS: All hospitalised COVID-19 patients aged ≥18 years in England between 1 March and 31 October 2020 were included. MAIN OUTCOMES AND MEASURES: This was a retrospective exploratory analysis using the Hospital Episode Statistics administrative data set. Multilevel modelling was used to explore the relationship between demographic factors, comorbidity and use of tracheostomy and the association between tracheostomy use, tracheostomy timing and the outcomes. RESULTS: In total, 2200 hospitalised COVID-19 patients had a tracheostomy. Tracheostomy utilisation varied across the study period, peaking in April-June 2020. In multivariable modelling, for those admitted to critical care, tracheostomy was most common in those aged 40-79 years, in males and in people of Black and Asian ethnic groups and those with a history of cerebrovascular disease. In critical care patients, tracheostomy was associated with lower odds of mortality (OR: 0.514 [95% CI 0.443 to 0.596], but greater length of stay OR: 41.143 [95% CI 30.979 to 54.642]). In patients that survived, earlier timing of tracheostomy (≤14 days post admission to critical care) was significantly associated with shorter length of stay. CONCLUSIONS: Tracheostomy is safe and advantageous for critical care COVID-19 patients. Early tracheostomy may be associated with better outcomes, such as shorter length of stay, compared to late tracheostomy.

Variability in COVID-19 in-hospital mortality rates between national health service trusts and regions in England: A national observational study for the Getting It Right First Time Programme.

BACKGROUND: A key first step in optimising COVID-19 patient outcomes during future case-surges is to learn from the experience within individual hospitals during the early stages of the pandemic. The aim of this study was to investigate the extent of variation in COVID-19 outcomes between National Health Service (NHS) hospital trusts and regions in England using data from March-July 2020. METHODS: This was a retrospective observational study using the Hospital Episode Statistics administrative dataset. Patients aged ≥ 18 years who had a diagnosis of COVID-19 during a hospital stay in England that was completed between March 1st and July 31st, 2020 were included. In-hospital mortality was the primary outcome of interest. In secondary analysis, critical care admission, length of stay and mortality within 30 days of discharge were also investigated. Multilevel logistic regression was used to adjust for covariates. FINDINGS: There were 86,356 patients with a confirmed diagnosis of COVID-19 included in the study, of whom 22,944 (26.6%) died in hospital with COVID-19 as the primary cause of death. After adjusting for covariates, the extent of the variation in-hospital mortality rates between hospital trusts and regions was relatively modest. Trusts with the largest baseline number of beds and a greater proportion of patients admitted to critical care had the lowest in-hospital mortality rates. INTERPRETATION: There is little evidence of clustering of deaths within hospital trusts. There may be opportunities to learn from the experience of individual trusts to help prepare hospitals for future case-surges.

Educational environment in intensive care medicine--use of Postgraduate Hospital Educational Environment Measure (PHEEM).

BACKGROUND: The educational climate is an important measure within medical education. This is because there are still accounts of poor teaching, humiliation, bullying and harassment of doctors in training. Deaneries and schools must be able to demonstrate to the Postgraduate Medical Education and Training Board that trainees are working and learning in a good environment. METHODS: This study used the Postgraduate Hospital Educational Environment Measure (PHEEM) to measure the educational climate in nine intensive care training schemes within hospitals in England and Scotland. 134 trainees replied out of 190 (71% response). Neither the identities of the nine units nor the trainees were known to the researchers. RESULTS: The results showed that there was a good overall educational climate in the intensive care units studied, with no racism or sexism, and trainees were happy with their teaching, their support and the work they did. The junior trainees (house officers and senior house officers) perceived a significantly better climate than did the senior trainees (specialist registrars). There were also significant differences in scores for the nine different intensive care units. CONCLUSIONS: PHEEM has proved to be a reliable and consistent tool to assess educational climate with an overall Cronbach's alpha of 0.921.

Ethics roundtable debate: should a sedated dying patient be wakened to say goodbye to family?

Intensivists have the potential to maintain vital signs almost indefinitely, but not necessarily the potential to make moribund patients whole. Current ethical and legal mandates push patient autonomy to the forefront of care plans. When patients are incapable of expressing their preferences, surrogates are given proxy. It is unclear how these preferences extend to the very brink of inevitable death. Some say that patients should have the opportunity and authority to direct their death spiral. Others say it would be impossible for them to do so because an inevitable death spiral cannot be effectively palliated. Humane principles dictate they be spared the unrelenting discomfort surrounding death. The present case examines such a patient and the issues surrounding a unique end-of-life decision.