The emerging specialty of perioperative medicine: a UK survey of the attitudes and behaviours of anaesthetists

Background: In 2014, the Royal College of Anaesthetists (RCoA) launched the Perioperative Medicine Programme to facilitate the delivery of best preoperative, intraoperative and postoperative care through implementation of evidence-based medicine to reduce variation and improve postoperative outcomes. However, variation exists in the establishment of perioperative medicine services in the UK. This survey explored attitudes and behaviours of anaesthetists towards perioperative medicine, described current anaesthetic-led perioperative medicine services across the UK and explored barriers to anaesthetic involvement in perioperative medicine. / Methods: Survey content based on the RCoA vision document was refined and validated using an expert panel. An anonymous electronic survey was then sent by email to the members of the RCoA. / Results: Seven hundred fifty-eight UK anaesthetists (4.5% of the RCoA mailing list) responded to the survey. Of these, 64% considered themselves a perioperative doctor, with 65% having changed local services in response to the RCoA vision. Barriers to developing perioperative medicine included insufficient time (75%) and inadequate training (51%). Three quarters of respondents advocate anaesthetists leading the development of perioperative medicine. / Conclusions: Despite evidence of emerging services, this survey describes barriers to ongoing development of perioperative medicine. Facilitators may include increased clinical exposure, targeted education and training and collaborative working with other specialties

Vigorous lateral export of the meltwater outflow from beneath an Antarctic ice shelf

The instability and accelerated melting of the Antarctic Ice Sheet are among the foremost elements of contemporary global climate change1, 2. The increased freshwater output from Antarctica is important in determining sea level rise1, the fate of Antarctic sea ice and its effect on the Earth’s albedo4, 5, ongoing changes in global deep-ocean ventilation6, and the evolution of Southern Ocean ecosystems and carbon cycling7, 8. A key uncertainty in assessing and predicting the impacts of Antarctic Ice Sheet melting concerns the vertical distribution of the exported meltwater. This is usually represented by climate-scale models3–5, 9 as a near-surface freshwater input to the ocean, yet measurements around Antarctica reveal the meltwater to be concentrated at deeper levels10, 11, 12, 13, 14. Here we use observations of the turbulent properties of the meltwater outflows from beneath a rapidly melting Antarctic ice shelf to identify the mechanism responsible for the depth of the meltwater. We show that the initial ascent of the meltwater outflow from the ice shelf cavity triggers a centrifugal overturning instability that grows by extracting kinetic energy from the lateral shear of the background oceanic flow. The instability promotes vigorous lateral export, rapid dilution by turbulent mixing, and finally settling of meltwater at depth. We use an idealized ocean circulation model to show that this mechanism is relevant to a broad spectrum of Antarctic ice shelves. Our findings demonstrate that the mechanism producing meltwater at depth is a dynamically robust feature of Antarctic melting that should be incorporated into climate-scale models

The Greenland and Antarctic ice sheets under 1.5◦C global warming

Even if anthropogenic warming were constrained to less than 2°C above pre-industrial, the Greenland and Antarctic ice sheets will continue to lose mass this century, with rates similar to those observed over the last decade. However, nonlinear responses cannot be excluded, which may lead to larger rates of mass loss. Furthermore, large uncertainties in future projections still remain, pertaining to knowledge gaps in atmospheric (Greenland) and oceanic (Antarctica) forcing. On millennial timescales, both ice sheets have tipping points at or slightly above the 1.5-2.0°C threshold; for Greenland, this may lead to irreversible mass loss due to the surface mass balance elevation feedback, while for Antarctica, this could result in a collapse of major drainage basins due to ice-shelf weakening

Observations beneath Pine Island Glacier in West Antarctica and implications for its retreat

Thinning ice in West Antarctica, resulting from acceleration in the flow of outlet glaciers, is at present contributing about 10% of the observed rise in global sea level. Pine Island Glacier in particular has shown nearly continuous acceleration and thinning, throughout the short observational record. The floating ice shelf that forms where the glacier reaches the coast has been thinning rapidly, driven by changes in ocean heat transport beneath it. As a result, the line that separates grounded and floating ice has retreated inland. These events have been postulated as the cause for the inland thinning and acceleration. Here we report evidence gathered by an autonomous underwater vehicle operating beneath the ice shelf that Pine Island Glacier was recently grounded on a transverse ridge in the sea floor. Warm sea water now flows through a widening gap above the submarine ridge, rapidly melting the thick ice of the newly formed upstream half of the ice shelf. The present evolution of Pine Island Glacier is thus part of a longer-term trend that has moved the downstream limit of grounded ice inland by 30?km, into water that is 300?m deeper than over the ridge crest. The pace and ultimate extent of such potentially unstable retreat are central to the debate over the possibility of widespread ice-sheet collapse triggered by climate change

Eddy transport as a key component of the Antarctic overturning circulation

The exchange of water masses across the Antarctic continental shelf break regulates the export of dense shelf waters to depth as well as the transport of warm, mid-depth waters towards ice shelves and glacial grounding lines. The penetration of the warmer mid-depth waters past the shelf break has been implicated in the pronounced loss of ice shelf mass over much of west Antarctica. In high-resolution, regional circulation models, the Antarctic shelf break hosts an energetic mesoscale eddy field, but observations that capture this mesoscale variability have been limited. Here we show, using hydrographic data collected from ocean gliders, that eddy-induced transport is a primary contributor to mass and property fluxes across the slope. Measurements along ten cross-shelf hydrographic sections show a complex velocity structure and a stratification consistent with an onshore eddy mass flux. We show that the eddy transport and the surface wind-driven transport make comparable contributions to the total overturning circulation. Eddy-induced transport is concentrated in the warm, intermediate layers away from frictional boundaries. We conclude that understanding mesoscale dynamics will be critical for constraining circumpolar heat fluxes and future rates of retreat of Antarctic ice shelves