17 research outputs found
Methods of the 7th National Audit Project (NAP7) of the Royal College of Anaesthetists: peri-operative cardiac arrest
Cardiac arrest in the peri-operative period is rare but associated with significant morbidity and mortality. Current reporting systems do not capture many such events, so there is an incomplete understanding of incidence and outcomes. As peri-operative cardiac arrest is rare, many hospitals may only see a small number of cases over long periods, and anaesthetists may not be involved in such cases for years. Therefore, a large-scale prospective cohort is needed to gain a deep understanding of events leading up to cardiac arrest, management of the arrest itself and patient outcomes. Consequently, the Royal College of Anaesthetists chose peri-operative cardiac arrest as the 7th National Audit Project topic. The study was open to all UK hospitals offering anaesthetic services and had a three-part design. First, baseline surveys of all anaesthetic departments and anaesthetists in the UK, examining respondents' prior peri-operative cardiac arrest experience, resuscitation training and local departmental preparedness. Second, an activity survey to record anonymised details of all anaesthetic activity in each site over 4 days, enabling national estimates of annual anaesthetic activity, complexity and complication rates. Third, a case registry of all instances of peri-operative cardiac arrest in the UK, reported confidentially and anonymously, over 1 year starting 16 June 2021, followed by expert review using a structured process to minimise bias. The definition of peri-operative cardiac arrest was the delivery of five or more chest compressions and/or defibrillation in a patient having a procedure under the care of an anaesthetist. The peri-operative period began with the World Health Organization 'sign-in' checklist or first hands-on contact with the patient and ended either 24 h after the patient handover (e.g. to the recovery room or intensive care unit) or at discharge if this occured earlier than 24 h. These components described the epidemiology of peri-operative cardiac arrest in the UK and provide a basis for developing guidelines and interventional studies
Direct evidence of fluid mixing in the formation of stratabound Pb–Zn–Ba–F mineralisation in the Alston Block, North Pennine Orefield (England)
The North Pennine Orefield Alston Block has
produced approximately 4 Mt Pb, 0.3 Mt Zn, 2.1 Mt
fluorite, 1.5 Mt barite, 1 Mt witherite, plus a substantial
amount of iron ore and copper ore from predominantly
vein-hosted mineralisation in Carboniferous limestones.
However, a significant proportion of this production
(ca. 20%) came from stratabound deposits. Though much
is known about the vein mineralisation, the relationship
between the veins and the stratabound mineralisation is not
well-understood. New petrographic, isotopic and fluid
inclusion data derived from samples of stratabound mineralisation
allow us to present a unified model that addresses
the genesis of both the vein and stratabound styles of
mineralisation. The mineralisation can be considered in
terms of three episodes:
1. Dolomitisation and ankeritisation Limestones in the
vicinity of the stratabound mineralisation were pervasively
dolomitised/ankeritised, and developed vuggy porosity
in the presence of a high-salinity brine consistent with
fluids derived from adjacent mud and shale-filled basins.
2. Main stage fluorite–quartz–sulphide mineralisation
Metasomatism of limestone was accompanied by
brecciation, dissolution and hydrothermal karstification
with modification of the existing pore system. The
open space was filled with fluorite, galena, sphalerite,
quartz and barite, formed in response to mixing of lowsalinity
sodic groundwater with high-salinity calcic
brine with elevated metal contents (particularly Fe up to
7,000 ppm) relative to “normal” high total dissolved
solids sedimentary brines.
3. Late-stage barite mineralisation paragenetically
appears to represent either the waning stages or the
distal portions of the main hydrothermal circulation
system under cooler conditions