| 1. |
- Khatri, C, et al.
(författare)
-
Outcomes after perioperative SARS-CoV-2 infection in patients with proximal femoral fractures: an international cohort study
- 2021
-
Ingår i: BMJ open. - : BMJ. - 2044-6055. ; 11:11, s. e050830-
-
Tidskriftsartikel (refereegranskat)abstract
- Studies have demonstrated high rates of mortality in people with proximal femoral fracture and SARS-CoV-2, but there is limited published data on the factors that influence mortality for clinicians to make informed treatment decisions. This study aims to report the 30-day mortality associated with perioperative infection of patients undergoing surgery for proximal femoral fractures and to examine the factors that influence mortality in a multivariate analysis.SettingProspective, international, multicentre, observational cohort study.ParticipantsPatients undergoing any operation for a proximal femoral fracture from 1 February to 30 April 2020 and with perioperative SARS-CoV-2 infection (either 7 days prior or 30-day postoperative).Primary outcome30-day mortality. Multivariate modelling was performed to identify factors associated with 30-day mortality.ResultsThis study reports included 1063 patients from 174 hospitals in 19 countries. Overall 30-day mortality was 29.4% (313/1063). In an adjusted model, 30-day mortality was associated with male gender (OR 2.29, 95% CI 1.68 to 3.13, p<0.001), age >80 years (OR 1.60, 95% CI 1.1 to 2.31, p=0.013), preoperative diagnosis of dementia (OR 1.57, 95% CI 1.15 to 2.16, p=0.005), kidney disease (OR 1.73, 95% CI 1.18 to 2.55, p=0.005) and congestive heart failure (OR 1.62, 95% CI 1.06 to 2.48, p=0.025). Mortality at 30 days was lower in patients with a preoperative diagnosis of SARS-CoV-2 (OR 0.6, 95% CI 0.6 (0.42 to 0.85), p=0.004). There was no difference in mortality in patients with an increase to delay in surgery (p=0.220) or type of anaesthetic given (p=0.787).ConclusionsPatients undergoing surgery for a proximal femoral fracture with a perioperative infection of SARS-CoV-2 have a high rate of mortality. This study would support the need for providing these patients with individualised medical and anaesthetic care, including medical optimisation before theatre. Careful preoperative counselling is needed for those with a proximal femoral fracture and SARS-CoV-2, especially those in the highest risk groups.Trial registration numberNCT04323644
|
|
| 2. |
- Watts, Hannah, et al.
(författare)
-
An Assessment of Geophysical Survey Techniques for Characterising the Subsurface Around Glacier Margins, and Recommendations for Future Applications
- 2022
-
Ingår i: Frontiers in Earth Science. - : Frontiers Media SA. - 2296-6463. ; 10
-
Tidskriftsartikel (refereegranskat)abstract
- Geophysical surveys provide an efficient and non-invasive means of studying subsurface conditions in numerous sedimentary settings. In this study, we explore the application of three geophysical methods to a proglacial environment, namely ground penetrating radar (GPR), seismic refraction and multi-channel analysis of surface waves (MASW). We apply these geophysical methods to three glacial landforms with contrasting morphologies and sedimentary characteristics, and we use the various responses to assess the applicability and limitations of each method for these proglacial targets. Our analysis shows that GPR and seismic (refraction and MASW) techniques can provide spatially extensive information on the internal architecture and composition of moraines, but careful survey designs are required to optimise data quality in these geologically complex environments. Based on our findings, we define a number of recommendations and a potential workflow to guide future geophysical investigations in analogous settings. We recommend the initial use of GPR in future studies of proglacial environments to inform (a) seismic survey design and (b) the selection of seismic interpretation techniques. We show the benefits of using multiple GPR antenna frequencies (e.g., 25 and 100 MHz) to provide decimetre scale imaging in the near surface (e.g., < 15 m) while also enabling signal penetration to targets at up to ∼40 m depth (e.g., bedrock). This strategy helps to circumvent changes in radar signal penetration resulting from variations in substrate conductivity or abundant scatterers. Our study also demonstrates the importance of combining multiple geophysical methods together with ground-truthing through sedimentological observations to reduce ambiguity in interpretations. Implementing our recommendations will improve geophysical survey practice in the field of glacial geology and allow geophysical methods to play an increasing role in the interpretation of glacial landforms and sediments.
|
|
| 3. |
|
|
| 4. |
- Watts, Hannah, 1994-
(författare)
-
Exploring beneath the surface of glacial landscapes : Implementing and improving geophysical investigations in glaciated environments
- 2024
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The warming climate is having profound impacts on glacier dynamics and extents. To improve our predictions of future ice mass changes, we require an enhanced understanding of both past and present glacial processes. The physical properties and structure of glacial sediments and landforms aid reconstructions of past environments and ice dynamics on numerous scales. Traditionally, these factors have been studied using glacial geological techniques such as sedimentary logging. While this provides valuable in situ data, there are numerous limitations, namely the limited availability and spatial extent of exposures. In recent decades, near-surface geophysical techniques have gained in popularity within the fields of glaciology, geomorphology, and sedimentology. Geophysics offers a non-invasive means of obtaining spatially extensive data on substrate properties and architecture, however issues such as signal scattering and interpretation ambiguity in complex glaciated environments restrict its application.This thesis exemplifies how near-surface geophysical techniques can aid glacial landscape interpretations focusing on ground-penetrating radar, seismic refraction, and multi-channel analysis of surface waves. It explores the current limitations of the methods and outlines solutions to improve their applicability, in terms of geophysical campaign success, as well as uncertainty estimation and visualisation. The reliability of geophysical interpretations can be improved by including direct substrate observations in campaigns. Here, the benefits of performing detailed sediment logging alongside geophysical surveys are exemplified, together with descriptions and explanations of associated method adaptations.Through a combination of method updates and applied studies, this thesis highlights the great potential for geophysical techniques in improving our understanding of glacial processes and outlines potential avenues for further work in this area.
|
|
| 5. |
|
|
| 6. |
- Watts, Hannah, et al.
(författare)
-
The sensitivity of seismic refraction velocity models to survey geometry errors, assessed using Monte Carlo analysis
- 2023
-
Ingår i: Journal of Applied Geophysics. - : Elsevier BV. - 0926-9851 .- 1879-1859. ; 208
-
Tidskriftsartikel (refereegranskat)abstract
- Seismic refraction models should routinely be reported with their associated uncertainty. Tomographic solutions are widespread, but estimating uncertainties in these via Monte Carlo simulation places great demands on computer resource, hence this task is often omitted. By considering the Plus-Minus method of seismic refraction interpretation, we use Monte Carlo simulations to evaluate the uncertainty in seismic refraction results and determine the sources of uncertainty that are most impactful on the reliability of the output model. Our analysis considers the impact of survey mislocation (i.e., geophones misplaced from a planned position) and interpretational problems (i.e., misidentification of first-break picks and uncertainty in identifying crossover distances) on the overall uncertainty in inferred unit thicknesses and seismic velocities. These are considered for synthetic data with varying subsurface velocity structure, and for field data collected at a shallow (< 50 m) bedrock site in north Wales (UK). Analysis of synthetic data shows that the impact of the aforementioned errors on thickness estimates is similar to 1000 times that on velocity estimates. Of all permutations tested, the most significant impact on thickness uncertainty was the accuracy of first-break picks, with the variance in target thickness estimates increasing roughly exponentially with first-break pick uncertainty. It is therefore prudent to minimise such uncertainty through appropriate survey practice (e.g., maximising source energy, taking multiple shots for stacking) and to properly define the resultant uncertainty in unit thickness and velocity estimates. The simplicity of the Plus-Minus method makes it an effective tool for highlighting the errors that would impact more sophisticated interpretation approaches, such as tomography or Full Waveform Inversion. The results from such analysis can be directly applied in straightforward environmental or engineering investigations and can be used to inform more advanced refraction methods. As such, the practice we highlight should be considered for any refraction interpretation.
|
|
| 7. |
|
|
| 8. |
- Bravo, L, et al.
(författare)
-
- 2021
-
swepub:Mat__t
|
|
| 9. |
- Tabiri, S, et al.
(författare)
-
- 2021
-
swepub:Mat__t
|
|
