Towards consensus on COVID-19

As the COVID-19 pandemic sees the UK enter lockdown, here we provide you with a summary of all our new COVID-19 material together with a moment’s respite from COVID-related information overload as we introduce the April 2020 issue of Anaesthesia

The first paper comes from Cook et al. and describes consensus principles for managing the airway in patients with COVID-19. The three overriding principles are SAS – Safe, Accurate and Swift. A one-page checklist is provided for tracheal intubation as are: tools for the prediction of difficulty; a plan for personal protective equipment; an example of kit dump mat; and a cognitive aid for an unexpected difficult tracheal intubation, including a ‘can’t intubate, can’t oxygenate’ scenario. The videolaryngoscope seems to be emerging as a key piece of equipment during this pandemic and this new paper from Hall et al. adds evidence to support this practice. They found that it significantly extends the ‘mouth-to-mouth’ distance from laryngoscopist to patient as compared with direct laryngoscopy. A lot of our learning comes from the experiences of our Italian colleagues, who have been at least two weeks ahead of most other nations. This new paper from Sorbello et al. describes these experiences together with clinical recommendations (Fig. 1). We were delighted to see the paper featured in the Independent. The key messages are planning, training and teamwork. With that in mind, Fregene et al. describe the use of in-situ simulation to evaluate the operational readiness of a high-consequence infectious disease critical care unit. They found that in-situ simulations identified multiple operational deficiencies on the critical care isolation room which allowed for corrective action before the admission of their first patient with COVID-19. Finally, this letter from Ong and Khee describes some key practical considerations in the anaesthetic management of patients during the COVID-19 pandemic

Figure 1 Suggested team roles and ergonomics for elective tracheal intubation.

One of the many significant findings of NAP4 was that awake tracheal intubation (ATI) – a technique enjoying high success and low complication rates – was frequently not utilised despite anticipation of difficult airway management. The new Difficult Airway Society guideline for ATI launched this month both empowers non-airway specialists to perform this when indicated and provides them with the technical tools to successfully do so. The document proposes a new lexicon for ATI according to technical approach: flexible bronchoscopy (ATI:FB), videolaryngoscopy (ATI:VL), or front of neck access (ATI:FONA), to name a few. Also outlined is a suggested method of ATI for the generalist, presented in an appealing visual format.

Figure 2 The Difficult Airway Society awake tracheal intubation (ATI) technique. This figure forms part of the Difficult Airway Society guidelines for ATI in adults and should be used in conjunction with the text. HFNO, high‐flow nasal oxygen; LA, local anaesthetic; FB, flexible bronchoscopy; MAD, mucosal atomising device; TCI, target‐controlled infusion; Ce, effect‐site concentration; VL, videolaryngoscopy. ©Difficult Airway Society 2019.

In the associated editorial, Aziz and Kristensen highlight the novel consultation of patients as part of the guideline’s creation, given the nature of ATI as requiring a well-informed, calm and cooperative patient. Also worthy of mention is the reliance on expert opinion, emphasising its capacity as advisory and not prescriptive, whilst advocating consistency of approach in a bid to promote patient safety. Aziz and Kristensen do not shy away from robust critique of other areas of the document, including its assertion that bleeding should be viewed as a relative contra-indication for ATI; the ‘sTOP’ acronym, which may be open to misinterpretation (appearing to suggest the correct sequence of events to be ‘sedate, topicalise, oxygenate, perform’); and how to proceed in the event of ATI failure. 

As the use of ATI increases, peri-operative blood transfusion is decreasing. In a five-year observational study from the USA, Nordestgaard and colleagues examined the peri-operative pathways of well over four million surgical patients, finding transfusion rates to have fallen from 8.4% in 2011 to 4.6% in 2016: a dramatic reduction of 45%.

Figure 3 Odds ratios for peri‐operative red blood cell transfusions for 2012–2016 vs. 2011. Error bars represent 95%CI.

Over the same period, there was no increase in myocardial infarction, stroke or all-cause 30-day mortality, suggesting that fewer transfusions had not unwittingly contributed to an increase in adverse events. Shah, Stanworth and Docherty, in the related editorial, explore the many reasons for this observed reduction, including survivorship bias and improvements in surgical technique. Data on cell salvage – a technique which rose to popularity over the course of the study – was unfortunately unavailable and could have provided valuable insights. Care must be taken not to assume that reduced transfusion is an entirely positive phenomenon – indeed, more liberal transfusion thresholds are appropriate in certain patient populations, such as traumatic brain injury. 

Blood transfusion has been variously implicated in the literature in terms of cancer recurrence and reduced survivorship. Tai and colleagues present retrospective data on this association in the context of post-surgical recurrence of liver cancer. Using a technique known as restricted cubic splines, permitting the application of linear regression models to non-linear data, they were able to demonstrate adjusted hazard ratios of 1.3 (95%CI 1.1-1.4) and 1.9 (95%CI 1.6-2.3) for recurrence and mortality, respectively. Moreover, the greater the number of units received, the stronger became the association with adverse outcomes. It is difficult to tease apart myriad confounding factors and assess causality here. In the related editorial, Dickson and Acheson rightly identify that any randomised controlled trial in this area would be ethically fraught – and so Tai and colleagues’ propensity matching is the closest approximation. Transfusion-related immunomodulation (TRIM) has been shown over time to not fully explain the deleterious effects of transfusion, given that we now live in the era of leucodepletion. Other related factors to consider are the role of individualised patient blood management (PBM) and the possible connection between certain anaesthetic and analgesic drugs and cancer recurrence. 

The latter controversial link is not, however, a central thread in White and Shelton’s compelling editorial arguing the case against inhalational anaesthetic agents. The considerable damage done to the environment from volatile agents has only recently entered the collective anaesthetic consciousness, with desflurane now eschewed by many institutions owing to its significant carbon footprint. White and Shelton reason that there is no single instance in which inhalational agents are absolutely indicated over total intravenous anaesthesia with or without locoregional anaesthesia, and that the conventional narrative of volatile anaesthesia as ‘standard’ and other methods as ‘alternative’ deserves to be challenged. They go on to outline the professional and governmental interventions that may support such a seismic shift in the future. 

A reduction in reliance on inhalational agents is likely to coincide with increased innovation in regional anaesthesia – already a ‘bumpy ride’, according to Mariano and El-Boghdadly’s editorial. In the accompanying randomised controlled trial, Ferre and colleagues present fascinating data on two different approaches to suprascapular nerve block and the corresponding risk of hemidiaphragmatic paralysis

Table 1 Incidence of hemidiaphragmatic paralysis in patients randomly allocated to anterior or posterior approach suprascapular nerve block. Values are number (proportion).

Obstetric anaesthesia is a famously litigious sub-specialty, as demonstrated anew by McCombe and Bogod’s review of over two decades’ worth of data on legal claims for nerve injury after neuraxial procedures by anaesthetists. This is the second in Anaesthesia’s new series, on ‘Learning from the Law’. The usual suspects, such as lack of informed consent (a factor in no fewer than 15% of the cases examined), and inadequate speed of response in the event of abnormal symptoms or delayed recovery of function, feature heavily. An analysis of the differing aetiologies of nerve injury is also presented alongside case excerpts. 

Buthelezi and colleagues present an important obstetric study from South Africa exploring the utility of phenylephrine and intravenous fluid co-loading in women undergoing elective Caesarean section. When compared with a conventional rescue bolus phenylephrine strategy, co-administration of the vasopressor with fluid decisively reduced the incidence of hypotension (systolic arterial pressure < 90 mmHg), without adverse effects or reduced Apgar scores in the neonates. These findings therefore demonstrate an efficient method to counter spinal-induced hypotension without the need for a syringe pump. The authors of this pragmatic trial are to be congratulated and their findings will be of assistance to clinicians in other resource-limited settings. 

Elsewhere we have: an exploration of the link between pre-operative anaemia and survival after orthotopic liver transplantation using regression modelsa prospective cohort study of intra-operative cell salvage in revision hip arthroplastya randomised controlled trial comparing shoulder block with interscalene brachial plexus block for shoulder arthroscopy; and a systematic review of single-use and reusable bronchoscopes with an accompanying cost effectiveness analysis. Over in Anaesthesia Reports we have reports of: airway fire during awake tracheostomy using high-flow nasal oxygentracheal resection and the importance of the team brief in multi-stage airway surgerypersistent intracardiac air bubbles after mitral valve surgerypostoperative hemiparesis due to conversion disorder; and pneumothorax following serratus anterior plane block

Finally, be sure to follow the blog in the upcoming weeks and months as we publish insights from across the globe into the COVID-19 crisis, having begun already with the Australian perspective by Dr Tanya Selak. In the meantime, check the excellent online COVID-19 repository for regular updates as the situation unfolds. 

Dr E-J Smith and Dr Andrew Klein

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