The corridor of uncertainty

Clinical decision-making is a strong theme throughout this month’s Anaesthesia. Using the example of cricket (more about the reason for this later!) ‘the corridor of uncertainty’ is an area a bowler aims to pitch their delivery so as to induce uncertainty in the batsman’s decision to play or leave, move forward or back, and defend or attack. Whether or not the correct decision was made soon becomes clear, particularly if a wrong shot, a late movement, hesitation or indecision result in a dismissal. The clinical corridor of uncertainty is arguably no different. We are pitched complex clinical problems and our job is to use knowledge, experience and ‘heuristics’ (more about that here) to make the best decisions for our patients. In anaesthesia and critical care, we soon find out whether or not we made the right choice too! This month’s edition is packed full of clinical content to help reduce uncertainty, guide decision-making and improve care for patients.

First up is a randomised controlled trial from Chambers et al. comparing leak, tidal volume and complications for cuffed vs. uncuffed tracheal tubes in children. They conclude cuffed tubes provide better ventilation and control of respiratory mechanics, are associated with less corrective measures following intubation and result in lower rates of adverse events (Table 1). Craig Bailey argues there is good evidence cuffed tubes enable accurate end tidal measurements, reduce theatre pollution, provide more reliable control of ventilation, are less likely to be exchanged for another sized tube and reduce the incidence of postoperative sore throat and pulmonary aspiration. Of course, such recommendations challenge the accepted wisdom of the last 50 years and we would very much like to know what you think. Will your practice change? Tell us!

 

Jan1_Table 1

Table 1 Peri-operative and postoperative respiratory complications for all patients by cuffed/ uncuffed groups. Values number (proportion). TT, tracheal tube

 

The 2017 Australian flu season was the worst seen for many years and so-called ‘Aussie flu’ (H3N2) is now here in the UK. The spread of influenza along with other respiratory viruses seems to be putting considerable pressure on UK hospitals, intensive care units and severe respiratory failure centres (SRFCs). For patients with severe respiratory failure, care can be escalated through referral, acceptance and transfer to a SRFC for the consideration of veno-venous extracorporeal membrane oxygenation (VV-ECMO). Gillon et al. report the results of their retrospective analysis of SRFC referrals to Guy’s and St. Thomas’ in central London. Six-month survival was 72.8% for those accepted to the service and 72.1% for those retrieved with VV-ECMO, which is higher than previously reported. Their results appear to support decision making and clinical practice at the study site and cast doubt on the use of scoring systems as compared with experienced clinical judgment. In their editorial, Charlesworth et al. distil the decision-making process for SRFC referrals into seven themes and conclude expert collaborative clinical assessment is, at present, an acceptable way to manage such referrals. If you are working in an intensive care unit this winter, there is a good chance you will care for patients with severe respiratory failure, so make sure you read these papers!

In their review article, van de Donk et al. discuss the pharmacokinetics and pharmacodynamics of sufentanil and examine its use for acute postoperative pain. They argue the sufentanil sublingual tablet system (SSTS) is effective and may even provide a future alternative to an intravenous morphine PCA system. Bantel and Laycock discuss and critique this evidence in the context of the tactics used by the pharmaceutical industry to promote gabapentin in the 1990s. They find many problems, including the publication of more reviews than original articles, ethical approvals granted by commercial review boards, methodological deficiencies and the use of ghost-writers for two manuscripts. They ask therefore, are SSTSs being promoted with the same marketing tools as used for gabapentin in the 1990s?

We often see discussions on Twitter with regards the documentation of laryngeal view as a means of recording the difficulty of intubation. In his editorial, Brian Jenkins discusses the documentation of ‘the view from the top’ in relation to an article by O’Loughlin et al., in which the accuracy and reliability of three scoring systems for reporting the glottic view at videolaryngoscopy are compared. He argues it is important to contextualise the grade recorded by documenting, as a minimum, equipment, technique, adjuncts and difficulties with obtaining a good laryngeal view. He also suggests the resultant record is an invaluable source of information for to the next operator and the recording of inaccurate or unreliable data should be regarded by all as potentially dangerous.

Continuing with the cricket theme (there was a reason we chose it!), Tavare and Pandit present their much anticipated statistically speaking article, ‘When rain stops play: a ‘Duckworth-Lewis method’ for surgical operating list productivity?’ Is it possible to compare the productivity of, for example, a cardiac theatre with two scheduled cases and a urology theatre undertaking ten operations in the same time period? It turns out we can use a well-known statistical method whose usual function is to calculate the target score for a team batting second in a limited overs match that is interrupted, typically by rain (Figure 1). In fact, the curves for operating theatre productivity are similar to the Duckworth-Lewis cricket model and the same principles seem to apply. Is working in the NHS the same as batting in the rain? The answer is educational, philosophical and entertaining, as is the article as a whole. We really enjoyed reading this one!

Jan1_Figure 1

Figure 1 Duckworth–Lewis performance curve relating resources (%, y-axis) to overs remaining (x-axis), as a function of wickets (isopleths). The resource % is then used to calculate the target score for the second team after an interruption.

 

Elsewhere this month we have a randomised controlled trial comparing high-flow nasal oxygen with standard management for conscious sedation during bronchoscopy, a description of real-time continuous monitoring of injection pressure at the needle tip for peripheral nerve blocks and a review of 21 years of litigation for pain during caesarean section. Finally, if you have exams on the horizon, need a paper for a journal club or simply want to become a statistics expert, we have completely re-organised and updated our special collections. Topics include cardiothoracics, guidelines, hip fractures, obstetrics, paediatrics, regional, research misconduct, statistics, reviews, training and education, and ultrasound. We hope you enjoy this month’s issue as much as we did and we look forward to discussing the articles with our followers on Twitter (each article we tweet is made #FOAMed for that day) in the next few weeks!

Mike Charlesworth, Editor Fellow

M_Charlesworth

Andrew Klein, Editor-in-Chief

A_Klein

Leave a Reply

Please log in using one of these methods to post your comment:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s