Kicking on while it’s kicking off

This month, we are beginning to see what many think may be the second surge of COVID-19 across Europe and elsewhere. Although some of the papers in this month’s issue were written and published during the first surge, they are now arguably more important than ever. First, Cook and Harrop-Griffiths discuss the many challenges of planned surgery, which includes time-critical and wholly elective procedures, in the context of the many issues affecting hospitals and the services they offer. We need to: manage the increased ICU activity associated with COVID-19; make hospitals safe places for staff, patients and relatives; ensure all patients are treated fairly; and look after our most important resource, our staff. Again, the challenges back in May are the same as those we face now and there are no easy answers. Professor Pandit suggests modelling might play a role when efforts are made to match demand and capacity (Fig. 1). Key questions include: how to set capacity; how to fund increased capacity; how to manage COVID-19 pathways; and how to manage demand. The current situation has forced us to increase capacity in the NHS and encouraged us to ask difficult questions about how we manage demand. As anaesthetists, we are well placed to influence the national agenda, which is what is needed to help us to learn to live with COVID-19.

Figure 1 Demand (which can be measured variously; horizontal black line) is constant over time so optimal capacity (red line 1) is easy to estimate. For varying demands shown, although mean demand is identical to the horizontal black line, the optimal capacities required to meet all the demand all the time increase (from dotted red line 2 to solid red line 3) as variation increases. However, this results in wasted capacity when demand falls to less than the peak. 

Should we routinely use hyperoxgenation in adult surgical patients whose tracheas are intubated? Weenink et al. argue that we should, and cite beneficial effects including: less surgical site infections; reduced postoperative nausea and vomiting; improved safety margins; and the use of hyperbaric oxygenation. These, they argue, outweigh any adverse effects, and they recommend the intra-operative administration of 0.80 fraction of inspired oxygen to non-critically ill adults whose tracheas are intubated. On the other hand, Sperna Weiland et al. go into more detail on the potential harms of hyperoxia, and argue its use to prevent surgical site infections is not supported by existing evidence. Where do you stand? Let us know over on Twitter!

This new randomised, crossover, simulation study from Schumacher et al. is the first to compare the use of modern respirators and powered respirators during advanced airway management procedures (Fig. 2). They found that videolaryngoscopy proved to have certain advantages whilst wearing respiratory protection, regardless of the type of protection used. When flexible bronchoscopic intubation was attempted, the use of protection did not significantly prolong attempts. Participants rated heat and vision significantly higher in the powered respirator group; however, noise levels were perceived to be significantly lower than in the standard respirator group.

Figure 2 Powered air‐purifying respirator with hood (left) and Standard air‐purifying respirator (right).

This systematic review and meta-analysis of observational studies from Armstrong et al. has an Altmetric score of 1148, which makes it our second most popular paper on social media, ever! It provides a message of hope for all of us facing a potential second wave, and shows how we have been able to adapt and improve outcomes for critically unwell patients with COVID-19 as our experience grows and learning accelerates. It is essential reading for all. Important also is this review of resilience strategies to manage psychological distress among healthcare workers during the COVID-19 pandemic, which builds on experiences from the SARS-CoV-1 and Ebola outbreaks. This new review from Sidebotham is a thought-provoking piece for many reasons, as it challenges everything we think we know about evidence-based medicine in peri-operative medicine and critical care. He concludes that, with the use of Bayes’ theorem, small underpowered randomised trials reporting weakly significant p values have a false positive risk of at least 50%. Likewise, large multicentre trials in critical care appear to have a high false negative risk. Is most of the evidence that underpins our clinical practice wrong? Charlesworth and Pandit outline some possible explanations and solutions, though the thought that every trial ever performed might need to be continuously repeated might be too much for some. Although such statistics may seem complex and inaccessible for most, they argue the way in which clinicians treat patients (and interpret clinical trials) is in fact Bayesian (Fig 3). 

Figure 3 The relationship between prior knowledge, clinical evidence and posterior knowledge from Bayes’ theorem are shown, for an example where the trial result (clinical evidence) shifts our final belief (posterior) towards accepting the intervention. Note that the precision (reflected in the width of the bell curves) of the posterior knowledge is tighter than prior knowledge and clinical evidence. The trial result (clinical evidence) may indicate a high probability of success of intervention, but our final belief will be tempered in a Bayesian framework: we do not accept this blindly. The distance between the distributions, their position and their precision arguably tell us more about the probability of success of an intervention than simply setting out to prove that something is true or false.

Elsewhere this month we have: a mixed methods analysis of factors influencing change in clinical behaviours of non-physician anaesthetists in Kenya following obstetric anaesthesia training; a study of surgical cancellation rates due to peri-operative hypertension; a study of the clinical validation of bioreactance for the measurement of cardiac output in pregnancy; a review of neuraxial anaesthesia and peripheral nerve blocks during the COVID-19 pandemic; and a qualitative systematic review of the role of serratus anterior plane and pectoral nerve blocks in cardiac surgery, thoracic surgery and trauma. Over in Anaesthesia Reports, we have a report of extraconal orbital emphysema secondary to barotrauma in a ventilated patient with COVID-19 and a persistent left superior vena cava with partial anomalous venous return in a liver transplant patient. We are delighted to have appointed four new Editors to the Anaesthesia and three new Assistant Editors to Anaesthesia Reports. They are: Ed Mariano; Louise Savic; Iain Moppett; Ben Morton; Maryann Turner; Rose Kearsley; and Lachlan Miles. In addition, we are delighted to announce that our new trainee fellow for 20/21 will be Craig Lyons from Dublin. Congratulations!

Finally, make sure you join us for our webinar on Saturday morning to find out who has won paper of the year together with some excellent presentations on the best peri-operative medicine research around in 2020

See you on Saturday!

Mike Charlesworth and Andrew Klein

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