Anaesthesia
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The protection of healthcare workers from the risk of nosocomial severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection is a paramount concern. SARS-CoV-2 is likely to remain endemic and measures to protect healthcare workers against nosocomial infection will need to be maintained. ⋯ In the absence of data specifically related to the risk of SARS-CoV-2 transmission in the peri-operative setting, we explore the evidence-base that exists regarding modes of viral transmission, historical evidence for the risk associated with aerosol-generating procedures and contemporaneous data from the COVID-19 pandemic. We identify a significant lack of data regarding the risk of transmission in the management of elective surgical patients, highlighting the urgent need for further research.
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In this review, Karmali & Rose challenge the dogma surrounding endotracheal tube sizing for adult anaesthesia, traditionally sizing based on sex.
What did they cover?
They explored both the functional consequences (good and bad) of ETT size, as well as airway trauma.
Noting that an ETT ≥ 6.0mm ID will accomodate most intraluminal devices, and in fact at these smaller sizes fibreoptic intubation or passage through an LMA is easier, however smaller tubes are more readily obstructed and deformed.
Ventilation through smaller ETTs
While smaller tubes may require slightly higher inspiratory pressures, these are generally not clinically significant with modern ventilators, and importantly do not translate to higher intra-tracheal or alveolar pressures experienced by the patient.
Similarly, expiratory gas flow is not significantly effected by a small ETT (6.0 mm) for most patients even at high minute ventilations (although use cautiously in patients with chronic airway limitation). Significant gas trapping at normal MV will start to occur with ETT < 5.0 mm.
Size and airway trauma?
While the internal diameter (ID) is important for anaesthesia conduct, it is the external diameter that matters for airway trauma (a standard 8.0 mm ID ETT has a 10.5 mm ED!).
They note while there is wide individual variation in tracheal dimensions, the trachea is narrowest at the subglottis – and thus adequate visualisation of the glottis at time of intubation is an incomplete indicator of the tube size suitability for the subglottis.
Not only do some adult women have an airway size at the lower-limit of acceptability for traditional 7.0-8.0 mm ETTs, but there is also correlation between ETT size and airway trauma, hoarseness and sore throat. A large ETT can result in mucosal ischaemia and ulceration after as little as 2 hours.
They conclude...
"Instead of opting for ‘the largest tube that the larynx will comfortably accommodate’, we perhaps should consider using the smallest tube which permits the safe conduct of anaesthesia."
For routine anaesthesia of ASA 1 & 2 patients, an ETT sized 6.0-7.0 mm is probably the best balance between ventilation needs and airway trauma.
Be smart
But remember, many of the concerns for tracheal tube trauma are based upon critical care experience, not anaesthesia. While a smaller tube is very likely beneficial for most elective adult patients, most benefit will simply be reduction in post-operative sore throat and hoarseness.
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Review
Management of the airway and lung isolation for thoracic surgery during the COVID-19 pandemic.
Intra-operative aerosol-generating procedures are arguably unavoidable in the routine provision of thoracic anaesthesia. Airway management for such patients during the COVID-19 pandemic including tracheal intubation, lung isolation, one-lung ventilation and flexible bronchoscopy may pose a significant risk to healthcare professionals and patients. ⋯ With appropriate modification, aerosol generation may be mitigated against in most circumstances. We developed a set of practice-based recommendations for airway management in thoracic surgical patients, which have been endorsed by the Association for Cardiothoracic Anaesthesia and Critical Care and the Society for Cardiothoracic Surgery in Great Britain and Ireland.
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Healthcare workers are at an increased risk of infection, harm and death from COVID-19. Close and prolonged exposure to individuals infectious with SARS-CoV-2 leads to infection. A person's individual characteristics (age, sex, ethnicity and comorbidities) then influence the subsequent risk of COVID-19 leading to hospitalisation, critical care admission or death. ⋯ However, the available evidence suggests that the risk for this group of individuals is not currently increased. This review examines factors associated with increased risk of infection with SARS-CoV-2, increasing severity of COVID-19 and death. A risk tool is proposed that includes personal, environmental and mitigating factors, and enables an individualised dynamic 'point-of-time' risk assessment.
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The COVID-19 pandemic has caused an unprecedented challenge for the provision of critical care. Anticipating an unsustainable burden on the health service, the UK Government introduced numerous legislative measures culminating in the Coronavirus Act, which interfere with existing legislation and rights. However, the existing standards and legal frameworks relevant to critical care clinicians are not extinguished, but anticipated to adapt to a new context. ⋯ Such a policy should be medically coherent, legally robust and ethically justified. The current crisis poses numerous challenges for clinicians aspiring to remain faithful to medicolegal and human rights principles developed over many decades, especially when such principles could easily be dismissed. However, it is exactly at such times that these principles are needed the most and clinicians play a disproportionate role in safeguarding them for the most vulnerable.