Principles for guidelines and guidelines for principles

This month, we are delighted to publish the concept and methods for the Project for Universal Management of Airways (PUMA) (Fig. 1). This extraordinary project aims to develop a single set of airway management guidelines that can be applied across various domains to improve implementation, promote standardisation and facilitate collaboration. Ahmad and Smith provide the accompanying editorial and ask, is there justification for yet another airway management guideline? They highlight how the methods used by Chrimes et al. are unique as well as highlighting issues which will need to be addressed by the authors in the forthcoming guidance. We simply cannot wait to see them!

Figure 1 Summary flowchart of the methodology used in the development of these guidelines. COVID, coronavirus disease 2019.

Last month, we brought together the authors of two papers with seemingly contradictory conclusions as well as an expert in aerobiology for #TheGreatAirwayDebate. The podcast has now been downloaded over a thousand times! We have a number of related papers this month, including this simulation study by Simpson et al., which shows that devices such as the aerosol box confer minimal to no benefit in containing aerosols during tracheal intubation. In their editorial, Turner et al. propose a framework for the safer adoption of a ‘McGyvered’ device, which includes a recommendation to not adopt, publish, endorse or disseminate via social media such devices without data to support safety. That said, social media was no doubt very useful during the early part of the pandemic for rapid knowledge transfer, as demonstrated by this editorial by Chan et al. along with their now famous infographic. Thankfully, we did not see any such devices attempting to solve the various issues associated with tracheostomy insertion, and instead this new guideline from McGrath et al. provides some sensible evidence-based practice recommendations. It will no doubt become very relevant once again for the second surge and beyond.

What are the additional risks during the peri-operative period attributable to new ways of working during the pandemic? Kane et al. report their retrospective observational cohort study and conclude there are low rates of COVID-19 infection in elective surgical patients despite a high burden of disease in the community. It seems the current bundles of peri-operative care along with stratified pathways work (Fig. 2). Should we be re-starting elective surgery? Well we obviously have and did so the short answer is yes, as safe surgery is essential for the management of non-communicable diseases and underpins good health and wellbeing. Efforts to ensure this can be done safely present us with enormous challenges that we are fighting collectively. This observational study by Okonkwo et al. is an excellent example demonstrating how it was done for paediatric surgery in north-west England

Figure 2 Urgent elective surgery care bundle during COVID‐19 surge. Details of key elements of the urgent elective surgery care bundle from planning to postoperative follow‐up and COVID‐19 status tracking. PPE, personal protective equipment.

We published recently an international multidisciplinary consensus statement on the prevention of opioid-related harm in adult surgical patients, and this new editorial by Bowen et al. calls for current ‘track and trigger’ tools to be updated to reduce opioid-induced ventilatory harm. They discuss risk factors, incidence, detection, sedation scores and track and trigger systems. Opioid-induced ventilatory impairment is a preventable iatrogenic harm, yet some patients have no identifiable risk factors. Is it time we monitored all patients receiving opioids for acute pain with a better designed track and trigger tool? The authors suggest so. 

When anaesthesia is maintained with intravenous drug infusions, real time analysis of the achieved concentrations is not routinely available. This new prospective observational study from Van Hese et al. finds that although target-controlled administration of propofol and remifentanil using the Marsh and Minto models allows clinically safe and stable conduct of anaesthesia, there were significant inaccuracies in both plasma and brain concentration predictions of these models. The Minto pharmacokinetic parameter set resulted in an underprediction of the plasma remifentanil concentrations by 72% and an overprediction of brain tissue remifentanil by 14%. Furthermore, the Marsh model showed an overall underprediction in both plasma and the brain by 12% and 81%, respectively, meaning that the measured brain tissue concentration was 81% higher than the effect‐site concentration predicted by the Marsh model (Fig 3). Irwin et al. suggest that some of the assumptions on which we base our models may be incorrect, and go into detail about what these models and assumptions are as well as their accuracy. They suggest that the issue of effect‐site concentrations probably exists for all anaesthetic drugs as a result of complex interactions with the blood brain barrier, including inhalational anaesthesia. After all, what we are measuring is the end tidal concentration and not the concentration of drug at the effect site in the brain. 

Figure 3 Relation between the performance error (PE) and the target concentrations in plasma and the brain. (a) Predicted TCI target concentrations of remifentanil were calculated using the pharmacokinetic parameter sets of Minto. Remifentanil plasma concentration (open circle); remifentanil effect‐site concentrations (filled circle). (b) Predicted TCI target concentrations of propofol were calculated using the pharmacokinetic parameter sets of Marsh. Propofol plasma concentrations (open diamond); propofol effect‐site concentrations (filled diamond).

Elsewhere we have: a review of COVID-19 infection risk during elective peri-operative carea statistical take on R0 (or more precisely, RE)a randomised study of programmed intermittent epidural bolus vs. patient centred epidural analgesia for maintenance of labour analgesia; and a study of the association of lung ultrasound images with COVID-19 infection in an emergency room cohort. Over in Anaesthesia Reports we have reports of: the use of the erector spinae block in obstetricsacute pulmonary oedema and hyperchloraemic metabolic acidosis following operative hysteroscopy using sodium chloride 0.9%apnoeic ventilation for shared airway surgery; and a novice anaesthetist working and living with malignant hyperthermia.

Finally, we will soon be publishing our 2021 supplement issue which is all about regional anaesthesia. Watch this space for some exciting news about how we aim to bring some of the great content to you in a new digitally immersive and interactive format! 

Mike Charlesworth and Andrew Klein