Postoperative pulmonary complications

It was an absolute pleasure to attend the recent GAT Annual Scientific Meeting in Glasgow and our congratulations go to all who made it a success. At the ‘Research in Anaesthesia’ session, we discussed what makes a paper popular and the important role of social media in modern academic publishing. The attention a paper receives on social media is something we take very seriously, as it provides instant feedback on likely long-term impact and, more importantly, an opportunity to share and discuss. ‘Impact Factor’ is a more traditionally cited metric, and this month we are delighted to announce a healthy increase in ours to 5.431. Academic anaesthesia is alive and kicking!

Our first article this month is a prospective observational study in 177 patients comparing the diagnostic accuracy of postoperative CXR and lung ultrasound for the detection of pulmonary complications following cardiothoracic surgery. Touw et al. conclude lung ultrasound may detect more clinically-relevant postoperative pulmonary complications than CXR, and at an earlier time point, which may aid more effective clinical decision-making. Though some have called for all such patients to receive lung ultrasound prior to critical care discharge, others urge for caution. We look forward to receiving your lettersand seeing the debate continue.

In November of last year, Bagchi et al. published their retrospective study of 109,360 patients receiving either pressure- or volume-controlled ventilation during surgery. Their study, which reports in favour of VCV, has since attracted much attention. In their editorial, Charlesworth and Glossop argue why they believe the mode of mechanical ventilation is less important than other ventilatory and non‐ventilatory aspects of perioperative care. They also discuss the evidence around postoperative pulmonary complications and their management, and the merits or otherwise of retrospective database analyses (Table 1). Could a similar study in the UK yield the same number of patients and level of detail? Probably not, and so regardless of the inference, their data are of great value to us all.

August_Table 1

Table 1.Advantages and disadvantages of retrospective database analyses

 

The act of delivering a general anaesthetic to patients introduces a number of detrimental physiological processes that predispose to the development of lung damage. Neuromuscular blocking agents (NMBAs) have been suggested as a contributing factor in this regard. Is it possible, therefore, to avoid their use prior to tracheal intubation when using a MAC videolaryngoscope? This study suggests a NMBA free anaesthetic is ‘no worse’ than when such agents are used as regards postoperative laryngeal morbidity and intubating conditions. If you are wondering what is meant by ‘no worse’, make sure you look out for next month’s Statistically Speaking!

 

It is difficult to study and make sense of the evidence for postoperative pulmonary and other systemic complications due to the variable way in which they, and factors contributing to their development, are defined. In their editorial, Armstrong and Mouton discuss the need for universally agreed definitions for anaesthetic techniques and standardised reporting criteria. For example, how ‘awake’ are patients when they are deeply sedated? This may cause problems for systematic reviewers when retrieving and analysing studies pertinent to ‘awake’ tracheal intubation, but more on that next month.

Sodium-glucose co-transporter type 2 (SGLT2) inhibitors are increasingly prescribed as second line therapy for diabetes mellitus. Recently, there have been a number of published case reports of euglycaemic ketoacidosis related to SGLT2 therapy, and this new review of the peri-operative implications of SGLT2s is, in our opinion, essential reading for all anaesthetists. Though SGLT2s seem to be safe overall, their cessation prior to major surgery, during acute illness, or in a state of volume depletion is recommended. An agent with which we are more familiar is dexamethasone, but is a single anti-emetic dose immunosuppressive or immune-activating? Probably both, concludes this new study in ten healthy male volunteers. Keeping with the peri-operative theme, is it possible to assess physical fitness prior to major surgery in those unable to pedal? This study from Durrand et al. is a significant step forward towards validating arm-crank cardiopulmonary exercise testing as an alternative to pedalling in patients with an abdominal aortic aneurysm.

Acute kidney injury following cardiac surgery is common and associated with significant morbidity and mortality. Many studies have tried to identify protective agents, but this new study is the first network meta-analysis of RCTs comparing these reno-protective drugs in the setting of cardiothoracic surgery. They conclude atrial natriuretic peptide (ANP) and levosimendan are the most protective but advise for cautious interpretation of these findings. Thankfully, Irwin and Choi provide context to this conclusion in their editorial while discussing the wider implications of Bayesian network meta‐analyses in anaesthesia. Though such studies should, in general, be interpreted cautiously, they should also be seen as a powerful tool to ‘flag’ the possibility that certain interventions are more effective than others, as is the case for ANP.

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Figure 1 Indirect evidence for A vs. B can be collected if head to head trials exist for A vs. C and B vs. C.

 

August_Figure 2

Figure 2Network loops for different drugs. The solid lines show head to head trials, and the dotted lines show evidence which can be collected indirectly. The thickness of the solid lines indicates the number of trials in that comparison.

 

Elsewhere this month there is a meta-analysis of videolaryngoscopy versus Macintosh laryngoscopy for double-lumen tube intubation in thoracic surgery, a primer on the ethics of teaching and learning in airway management, a qualitative study of human factors enablers and barriers for successful airway management, an in-vitro study of the accuracy of near-patient versus inbuilt spirometry for monitoring tidal volumesand a discussion of NCEPOD at the age of 30.

 

Over in Anaesthesia Cases, recently published case reports include awake tracheal placement of the Tritube® under flexible bronchoscopic guidance, successful left-sided one-lung ventilation using two Arndt endobronchial blockers in a patient with right tracheal bronchusand sevoflurane for the treatment of refractory status epilepticus in the critical care unit. We want you to send us your interesting cases! Finally, this is the last issue in the current style. Next month, we will have new branding, a new logo and a completely new look journal. We look forward to receiving your feedback!

M_Charlesworth                          A_Klein

 

Mike Charlesworth                   Andrew Klein

Trainee Fellow                         Editor-in-Chief

Pragmatic peri-operative research

Two years ago, joint guidelines from the AAGBI and British Hypertension Society were published. They were the first to advise on the measurement, diagnosis and management of raised blood pressure prior to planned surgery and were warmly welcomed by all stakeholders. Despite this clarity, peri-operative research on the consequences of pre-operative hypertension is lacking. This month, Crowther et al. report their study on the association between pre-operative hypertension and intra-operative haemodynamic instability. Though they conclude pre-operative hypertension may be more common than we think (48% vs. 30%), they were nonetheless unable to establish a link between pre-operative hypertension and the incidence of intraoperative haemodynamic instability. A key recommendation from the authors is these data support the current AAGBI hypertension guideline.

 

In this month’s statistically speaking, Choi and Wong explore the methods used and the conclusions deduced by Crowther et al. They discuss the difficulties of research on the consequences of pre-operative hypertension, the pitfalls of prospective observation and the clinical context of the study. They argue the study is inherently limited due to a low signal-to-noise ratio, and larger studies with more precise recruitment strategies will be required to better study the association between pre-operative hypertension and peri-operative morbidity.

 

Next, this retrospective observational study from Palmer et al. aims to elucidate the association between anaesthetic technique, operating room-to-incision interval and neonatal outcome in emergency caesarean section. Unsurprisingly, general anaesthesia was the quickest (6 minutes) followed by spinal anaesthesia (11 minutes), epidural top-up (13 minutes) and combined spinal-epidural (24 minutes). Alarmingly, general anaesthesia was associated with fewer 5-minute Apgar scores ≥ 7. Despite this finding, some have already highlighted several study limitations and engaged with the authors on Twitter. We look forward to seeing this discussion develop and we invite all interested parties to send us their letters.

 

In another observational study of 164 patients aged at least 65-years presenting for unscheduled surgery, McGuckin et al. evaluate the association between frailty and common postoperative surgical outcomes. Though the duration of hospital stay was independently associated with ASA physical status, surgical severity and two commonly used scoring systems (E-POSSUM and SORT), frailty, as measured by the Clinical Frailty Score, was not independently associated with hospital stay, morbidity, mortality or readmission.

 

The limitations of observational studies are well understood yet their conclusions may affect the way we care for patients. Though large pragmatic randomised controlled trials in peri-operative decision-making are seen by many as the gold standard, is this really the case? Joshi et al. set out the fundamental issues with such trials that may explain why negative results are commonand argue clinical practice may be falsely influenced through a failure to recognise these limitations. On the other hand, Yeung et al. set out the arguments for conducting large randomised trials and clarify when and how they should be performed. They argue the need for such studies has never been greater, and their limitations can be negated through more thoughtful trial design. When the results of large scale randomised trials are unwelcome or unexpected, do we simply dispute their findings due to our own biases? The debate will no-doubt continue.

 

There are three RCTs this month and all have important clinical consequences. The first is an investigation of the effect of spinal hyperbaric bupivacaine–fentanyl or hyperbaric bupivacaine on uterine tone and foetal heart rate (FHR) in labouring women.They find that spinal hyperbaric bupivacaine offers similar pain relief yet with a lower incidence of FHR abnormalities as compared with a hyperbaric bupivacaine-fentanyl combination. The second is a comparison of bolus phenylephrine or ephedrine for the treatment of hypotension in women with pre‐eclampsia undergoing caesarean section(you can read the recent associated consensus statement here!). They conclude 50 mcg phenylephrine and 4 mg ephedrine, administered as intravenous bolus doses, resulted in similar foetal acid‐base status and effectiveness in treating hypotension in pre‐eclamptic patients undergoing caesarean section. Finally, Mendonca et al. report their RCT comparing the ‘sniffing’ and neutral position using channelled (KingVision®) and non‐channelled (C‐MAC®) videolaryngoscopes(Figure 1). They failed to demonstrate any difference in ease of intubation between the positions for both types of videolaryngoscope and argue that videolaryngoscopy, like direct laryngoscopy, should be regarded as a dynamic process in which a change in position should be considered when difficulty is encountered.

July_Figure 1

Figure 1 Channelled, non‐channelled videolaryngoscopes and bougie used in the study. (a) KingVision with tracheal tube loaded in the channel. (b) C‐MAC with D‐Blade and (c) Frova intubating catheter (bougie).

 

The mode of anaesthesia for patients with hip fracture has been discussed at length for many years. In 2012, the AAGBI published their guideline for the management of proximal femoral fracturesand in 2016, following a secondary analysis of ASAP2 data, White, Moppett and Griffiths called for standardisation of anaesthetic practices. This month, we are delighted to publish this consensus statement on the principles of anaesthesia for patients with hip fracture. We encourage all who care for such patients to study these principles and for hospitals to incorporate each into local protocols. The core principle is simply to do your best for every patient. Refreshingly, particular techniques, drugs or modes of anaesthesia are not definitively prescribed.

 

Elsewhere this month, there is a benchtop study of changes in hardness and resilience of i‐gelTMcuffs with temperature, a systematic review of topical benzydamine for prevention of postoperative sore throat in adults undergoing tracheal intubation, a meta-analysis of combined spinal‐epidural vs. spinal anaesthesia for caesarean sectionand an excellent discussion of the law around caring for obstetric patients with mental illness. Have you been involved with the management of an interesting case recently? Please consider writing it up for our sister journal, Anaesthesia Cases. Recent cases include acute postoperative compartment syndrome in a child receiving patient-controlled analgesia and peripheral nerve blockand Takotsubo cardiomyopathy secondary to needle phobia (this one received a lot of interest on social media!).

 

Finally, congratulations to our new fellow, Dr Akshay Shah, a talented NIHR Doctoral Research Fellow from Oxford. We look forward to Akshay joining the editorial team at the AAGBI Annual Congress in Dublin. The standard of applicants this year was exceptionally high, and our commiserations go to those who were unsuccessful. We have recently taken the decision to concentrate efforts on our Twitter accountinstead of our Facebook page. We do, however, have an Instagram accountwhere you can find out which paper is freely available each day and gain an insight into the day to day business of the journal. Finally, we will have a fresh new journal design from September onwards and we look forward to hearing what you think. Several articles in the new design are available now over on early view.

 

That’s all for now, but we hope to see you in a couple of weeks for the GAT annual scientific meeting in Glasgow!

 

M_Charlesworth                        A_Klein

Mike Charlesworth                   Andrew Klein

Trainee Fellow                         Editor-in-Chief

 

 

 

The Airway App: a clarion call!

Two months ago, we held our first Tweet Chat of the year where the preliminary results from The Airway App, a new tool for capturing eFONA experiences,were discussed. We heard from the authors of the paper, researchers, clinical experts, users of the app and other interested parties. There is uncertainty regarding which eFONA technique(s) is/are most effective, yet previous research and audit strategies have arguably increased rather than resolved this uncertainty. Studying rare events such as eFONA is notoriously difficult, with many barriers to capturing such cases in sufficiently accurate detail. The Airway Appis a smartphone application, freely available to download, that permits the anonymous reporting of eFONA experiences to a central database. In their paper, Duggan et al. report 99-real patient eFONA procedures as reported from 21 countries around the world. Interestingly, only 32% of procedures were carried out by anaesthetists, 65% were for ‘cannot intubate, cannot oxygenate’ and the most popular technique was ‘scalpel-bougie cricothyroidotomy’, with 37/45 successful at first attempt for all 99 cases.

 

In their editorial, Greenland and Irwin discuss the strengths and weaknesses of The Airway App in the context of other strategies to study cases of eFONA. Although the use of modern innovative research methods such as The Airway Appmay reach the places traditional methods cannot, they argue the successful management of a ‘cannot intubate, cannot oxygenate’ scenario is strongly influenced by complex psychological aspects together with technique familiarity over and above the method chosen. Regardless, we call for all to download the application and to spread the word to colleagues. Additionally, if you hear of a case of eFONA in your hospital, please ask the individuals involved to anonymously report it using The Airway Appso we may collectively learn from such cases.

 

We are now accepting applications for a one-year Fellowship attached to the Journal, starting at the AAGBI Annual Congress in September 2018. The deadline is the 31stof May 2018 and the advert for the post can be found here. This month, our previous fellows Annemarie Docherty and Kariem El-Boghdadly report their paper, which is the first to study the distribution and scholarly output of individual anaesthesia research grants. Data on 121 grant awards accounting for £3.5 million were collected, of which 91 completed studies resulted in 140 publications and 2759 citations. The overall cost per publication and citation was £14,970 and £1515 respectively. In response, the NIAA issued a press release stating although UK anaesthesia receives significantly less research funding than other speciality areas, the cost per publication represents superior value for money in comparison to these other speciality areas.

 

June.Figure 1

Figure 1 Geographical location of NIAA grant applications from the UK (a) and London (b) as well as grants awards in the UK (c) and London (d). The size of the dots represents the amount of money applied for, and the colour of the dots reflects the number of applications (a and b) or the success rate (c and d) Because London had >80% of grant applications and awards, it has been plotted separately.

 

In their accompanying editorial, Pandit and Merry discuss these results in the context of research waste, the link between funding and publication and the building of academic capacity. They argue if we are truly to serve our patients as anaesthetists, we need our practice to be informed by well-conducted research. The results of El-Boghdadly highlight many areas in which this research can be improved. In their editorial, Smith and Irwin also discuss the results of El-Boghdadly, but this time in the context of potential dilemmas for the NIAA, the responsibilities of funders and meaningful measures of impact. They argue it is disappointing that 20% of grant recipients (representing ~£700,000 of funding) did not respond to the survey. The centres concerned are listing in an online appendix which can be found here.

 

June.Table 1

Table 1 Forms of research waste

 

Recently, the ‘Get it right first time’ (GIRFT) report for cardiothoracic surgery was published and a number of quality improvement recommendations were highlighted. Quality improvement through reducing variation with initiatives such as enhanced recovery after surgery (ERAS) often meets many barriers, despite good evidence of benefit from such protocols. This paper by Smirk et al. studies the use of a ‘Greenie Board’ from The US Navy as adapted to the scenario of adherence to the anaesthesia-related components of an established ERAS protocol. They conclude the use of an audit and visual feedback system for anaesthetists, such as the Greenie Board, can improve and sustain compliance to process measures, such as an ERAS protocol, with potential for improved surgical outcomes.

 

June.Figure 2

Figure 2 The components of the ERAS protocol assessed for compliance and how each anaesthetist’s score is translated to a colour block on the Greenie Board.

 

June.Figure 3

Figure 3(a) The baseline audit of Greenie board data (pre‐implementation). (b) The post‐implementation Greenie board (six months after implementation).

 

In their editorial, Levett and Grocott argue this low-cost intervention could improve the reliability of delivery of anaesthetic care. For example, we would be disappointed if our garage mechanic chose to only complete some aspects of a required car service, so why should the perioperative care patients receive be subject to such variation? In the era of marginal gains and continuous gradual incremental improvements in healthcare, such initiatives as those presented by Smirk et al. may do much more to improve patient outcomes than any randomised controlled trial. (…but more on the why, when and how of pragmatic trials in perioperative medicine next month!)

 

Another important study this month is this narrative review of nerve blockade for the early management of elderly patients with hip fracture. (You may also want to head over to early to read this new consensus statement on the principles of anaesthesia for patients with hip fracture.) A key conclusion is the recommendation that nerve blocks, such as the fascia iliaca block, should be incorporated into routine multi-modal acute pain management protocols. Overall, this fresh approach to hip-fracture pain management, through an up-to-date evidence synthesis, is essential reading for all routinely caring for such patients, whether in the emergency department, on the orthopaedic ward, in theatre or elsewhere.

 

In this month’s Statistically Speaking, Choi and Wong discuss statistical prediction in relationto a previous study of gastric ultrasound vs. clinical assessment in paediatric patients. They conclude that, according to the results of the study, judging gastric content by asking patients about their recent intake is no better than tossing a coin! Elsewhere this month there is a clinical guideline on pre-operative exercise training in patients awaiting major non-cardiac surgery(this has already proved popular on Twitter!); a case-report of ECG failure in the operating room; a study of the association of postoperative mortality with time of day, week and year; a study of tranexamic acid in trauma patients; and muchmore!

 

We began with a clarion call for all clinicians to download The Airway Appand spread word of its existence. We end with two further such requests. Firstly, if you know any trainees with an interest in the research process who may be interested in applying for our one-year fellowship programme, please ask them to get in touch. Finally, if you have recently managed an interesting case please consider writing it up for our sister journal, Anaesthesia Cases! Recent cases include the use of THRIVE for rigid bronchoscopy in a nonagenarianand a neurogenic tumour of the posterior mediastinum with symptoms of sympathetic ganglia block.

That’s all for this month. We hope you enjoy the June issue as much as we did. See you over on Twitter!

 

M_Charlesworth                      A_Klein

Mike Charlesworth                 Andrew Klein

Trainee Fellow                        Editor-in-Chief

Step back before you pack

There are many qualities we consider when deciding whether or not to accept submitted manuscripts for publication. (Read all about the fate of manuscripts rejected from Anaesthesia here.) Obvious items include originality, quality, clinical applicability, and for clinical trials, the prospective trial registration status….but more on that later. This month in Anaesthesia, Athanassoglou et al. employ a systematic review to ask whether or not there is evidence on which to base the practice of anaesthetic throat pack insertion. The striking finding is that all the evidence is of harm, with no apparent benefits associated with the use of anaesthetic throat packs. The authors, together with the National bodies DAS, BAOMS and ENT-UK, devised an evidence-based consensus statement recommending the routine use of throat packs inserted after induction by anaesthetists should be abandoned (Figure 1).

 

Figure 1

Figure 1 Consensus protocols for throat pack use. There is no indication for the routine insertion of a throat pack by an anaesthetist at or after induction or tracheal intubation in upper airway surgery. The protocol to be followed depends on whether it is judged best for the surgeon to site the pack (as when the pack will be within the operative field), or for the anaesthetist to site the pack (as when the pack is outside the operative field). (*The anaesthetist may be asked to assist, for example, with laryngoscopy; **notwithstanding cases where the jaw is wired, patient transferred ventilated to intensive care, etc, or where a pack is intentionally left in‐situ).

Have we therefore reached the end for throat packs inserted by anaesthetists? Craig Bailey et al. argue the new practice recommendations, as they stand, do not address all the pertinent issues. Advice is offered in light these new recommendations for five common anaesthetic throat pack indications and anaesthetic departments may wish to incorporate this into any new throat pack protocols (Table 1).

Table 1

Table 1 Indications for throat packs and the advice of Bailey et al.

 

Does surgery and anaesthesia affect cognition in adults without existing cognitive dysfunction? This observational study finds an association between surgery, the number of operations and longer cumulative operations with a decline in immediate memory. The declines were small but significant, and the rate of deterioration was greater in those with lower performance at enrolment. Despite these seemingly striking results, it is probably too early to recommend any changes to clinical practice regarding the prevention, diagnosis, management and prognosis of cognitive changes after surgery. This paper is, nonetheless, essential reading for all anaesthetists.

Imagine a journal receives a randomised controlled trial reporting on an area important to patients and clinicians, funded through charitable donations and/or taxes, and with important scientific conclusions. The authors, however, did not register their trial prospectively through a recognised registry. Should such papers be rejected automatically or dealt with in a flexible and pragmatic manner? El-Boghdadly et al. present the findings from their study into adherence to guidance on the registration of randomised controlled trials published in Anaesthesia. They conclude that, though generally encouraged as good practice, trial registration was not associated with the acceptance of manuscripts submitted to Anaesthesia or subsequent citation metrics. In their editorial, Pandit and Klein discuss the many reasons for this editorial policy and call for the consideration of other options, such as the automatic upload of all trial protocols, correspondence and associated documents by the ethics committees granting approvals. They question whether or not automatic rejection of unregistered prospective research is itself ethical, as patients have already been subjected to the intervention in an ethically approved manner. On the other hand, Smith and Dworkin argue trial registration is the best method currently available to verify whether articles are reporting results from pre-specified hypothesis and methods, and to address concerns about selective reporting, falsely positive results and selective publication. What do you think? Who wins the argument? Join in the discussion either on Twitter or through our correspondence website.

The Difficult Airway Society recently issued new guidelines for airway management in critical ill adults. In their editorial, Professors Pandit and Irwin discuss the implications of these new recommendations for anaesthetic departments. It seems the way we think about an airway with predicted difficulty in critical illness needs to change. For example, appropriate assistance should be available from the start, rather than when problems arise later on. ‘Fast track’ extubation following airway difficulty is generally inappropriate, and planned extubations should only be attempted during daytime hours. The question is, can our hospitals adapt to these guidelines, which will no doubt improve patient safety?

We have seen several recent papers comparing the efficacy and safety of sugammadex as compared with neostigmine for the reversal of neuromuscular blockade. (For an excellent up-to-date clinical summary of sugammadex, including when we should consider using it, check out this editorial.) This month, a Cochrane systematic review concludes that sugammadex works far more quickly than neostigmine and is associated with fewer adverse events (Figure 2). Some may argue, however, that we will only be able to fully appraise the safety of sugammadex when its use becomes more widespread, at least in the UK.

 

Figure 2

Figure 2 Forest plot of risk of adverse events; sugammadex (any dose) vs. neostigmine (any dose). M‐H, Mantel‐Haenszel.

 

Does transnasal humidified rapid-insufflation ventilatory exchange (THRIVE) prevent hypoxia when apnoea is prolonged due to difficulty with intubation for rapid sequence induction in adults? (Read the landmark THRIVE paper by Patel and Nouraei from 2015 here!) This randomised controlled trial in 79 patients, where THRIVE was compared with facemask pre-oxygenation, seems to suggest so (Figure 3). THRIVE may therefore provide continuous oxygenation rather than just pre-oxygenation and be useful for rapid sequence inductions.

 

Figure 3

Figure 3 CONSORT diagram. THRIVE, transnasal humidified rapid‐insufflation ventilatory exchange; GA, general anaesthesia; RSI, rapid sequence induction; BMI, body mass index.

 

In this month’s ‘statistically speaking’, Choi et al. ask questions of before-and-after studies in relation to an article previously published in March by Ångerman et al. Of course, randomised controlled trials are not always feasible nor ethical, but before-and-after studies introduce sources of bias such as changes in patient characteristics, treatments and medications, lack of blinding during data collection and the continuous gradual improvements in the standard of care. Despite these and other limitations, there is no-doubt that before-and-after studies can be informative and useful. Maybe we should always view data collected today as potentially controlling for trials conducted in the future?

Anaemia is common before cardiac surgery in the UK and is independently associated with increased morbidity and mortality in such patients. This retrospective observational study finds that the WHO definition for anaemia significantly underestimates the number of women at increased risk of morbidity associated with anaemia before cardiac surgery (Figure 4). Would women benefit from a threshold of anaemia set to Hb < 130 g.l-1? There is clearly a need for a well-designed prospective study. (Read all about the controversy around diagnostic criteria for preoperative anaemia in women here.)

 

Figure 4

Figure 4 Relationship between pre‐operative Hb level and postoperative length of stay in women (white circles) and men (black diamonds). Hb, haemoglobin; LOS, length of stay.

 

Elsewhere this month there is a narrative review of the anomalies with target-controlled infusions (a must read for TIVA enthusiasts!), a simulation study of the effect of palpable vs. impalpable cricothyroid membranes in an emergency front-of-neck access scenario, an assessment of the tolerability of the Cook Staged Extubation Wire in patients with known or suspected difficult airways extubated in intensive care and a randomised controlled trial of the ilioinguinal–transversus abdominis plane nerve block for elective caesarean section.

Our most discussed article from the April issue was this case-series of general anaesthesia-free major breast surgery by Pawa et al. Does the choice of anaesthesia matter for such patients? This secondary analysis of patients enrolled in an ongoing clinical trial seems to suggest so, as it concludes that propofol-paraverterbral anaesthesia attenuates the postoperative increase in neutrophil-lymphocyte ratio, a potentially important marker of inflammation and immunosuppression.

Finally, applications are invited for a 1-year Fellowship attached to the journal, starting at the AAGBI Annual Congress in September 2018. The deadline for applications is 31st May 2018 and all the information on how to apply can be found here. We hope you enjoy the May issue of Anaesthesia as much as we did and, as always, we look forward to discussing each article with you and receiving your feedback on Twitter.

 

Mike Charlesworth                                    Andrew Klein

Trainee Fellow                                            Editor-in-Chief

Time to retire the stethoscope?

There is an old medical aphorism, still taught today, that a careful history will lead to the correct diagnosis 80% of the time. Clinical history taking is largely the same today as it was twenty or so years ago, yet clinical examination seems to be evolving. Enthusiasts are continually generating evidence that may one day prove that point-of-care ultrasound is superior to traditional clinical assessment, such as auscultation through a stethoscope (read all about the history of the stethoscope here!). For example, just last month we saw how gastric ultrasound changed the choice of general anaesthetic induction technique for non-elective paediatric surgery and was able to discriminate high from low gastric volumes in the third trimester of pregnancy.

This month in Anaesthesia, Canty et al. present the results of their pilot multi-centre RCT of the impact of pre-operative cardiac ultrasound in patients having surgery for femoral neck fractures. They conclude it is feasible to randomise patients to a group that underwent preoperative focussed cardiac ultrasound or a control group that did not, and there was a treatment effect favouring cardiac ultrasound in terms of their composite primary outcome (more about those here!). In order to definitively quantify this effect, a large randomised controlled trial requires around 1000 participants. This would take roughly three years across 13 sites. Remarkably, cardiac ultrasound led to a change in diagnosis for several participants for which their management was either stepped-up or down (Table 1).

April2018_Table 1.jpeg

Table 1 Stepped-up/down treatment changes after re-diagnosis using focused cardiac ultrasound.

 

So just what is a pilot study, why is there no sample size or power calculation and why is there an emphasis on protocol feasibility rather than clinical and statistical significance? For the answer to these questions, look no further than this month’s ‘Statistically Speaking: Demystifying Methods’ by Choi et al. They argue there should be an appreciation of the manner in which cardiac ultrasound is performed and interpreted. Though the intervention is ‘diagnostic’ in nature, it provides a guide as to the overall cardiovascular picture of the patient and thus informs management choices such as, amongst others, anaesthetic technique and fluid management. Is it therefore time to retire the stethoscope? Probably not just yet, as there are many barriers to the widespread implementation of point of care ultrasound at this present time. Despite these barriers, the article by Canty et al. adds to the growing weight of evidence suggesting tomorrows doctors may one day be learning about the Nyquist limit in the place of where they once studied the grading system for murmurs. The question is, what will tomorrows doctors think about the fact we continue to use stethoscopes to make clinical decisions in 2018?

Ultrasound is a strong theme throughout this month’s issues. For example, do you always ‘Stop-Before-You-Block (SBYB)? Hopping et al. undertook an online survey and conclude that one in four anaesthetists have performed a wrong-sided block (something classed as a never event, more about these here!) and ~41% perform SBYB at a time-point that is much earlier than intended by the campaign. In the accompanying editorial, Moppett and Shorrock argue we should think about wrong sided blocks using a theoretical understanding of human work (Figure 1). Paying more attention to the interaction between work-as-done, -disclosed, -imagined and -prescribed in the healthcare setting may have benefits beyond reducing the frequency of rare events, such as wrong-sided blocks.

 

April2018_Figure 1.png

Figure 1 The four varieties of work

 

There are many reasons why a general anaesthetic is not always the best choice for a patient. Based on their prospective observational case-series of 16 patients, Pawa et al. argue it is feasible to undertake major breast surgery with combined thoracic paravertebral and pectoral nerve blocks under sedation. They also demonstrate a high level of satisfaction and acceptability from both patients and surgeons. Elsewhere, a randomised controlled trial from Chin et al. concludes neuraxial ultrasound assistance increases first-pass success and decreases needle movements during CSE placement for caesarean section, particularly in women with easily palpable spinous processes (Table 2).

 

April2018_Table 2.jpeg

Table 2 First-pass success and CSE procedure difficulty according to technique. Values are number (proportion).

 

Postoperative atrial fibrillation (AF) is likely to become an increasing problem for peri-operative medicine practitioners in the future for many reasons. This systematic review finds its incidence following general surgery is around 10% with risk factors including increasing age; history of cardiac disease; and postoperative complications, particularly, sepsis, pneumonia and pleural effusions. The incidence of AF following thoracic surgery is greater for several reasons, and the choice of analgesic regimen is probably important. This propensity matched study (more about propensity matching here!) concludes outcomes after thoracic surgery are no worse following paravertebral blockade as compared with thoracic epidural anaesthesia. In the accompanying editorial, Short and Kamalanathan ask whether analgesia has changed for lung resection surgery? They argue there is no evidence to prove one technique is superior to another for open procedures and we should nevertheless focus efforts on appraising analgesic regimens for VATS, as such surgery is becoming more common in the UK.

Should we use hyperbaric or isobaric bupivacaine for spinal anaesthesia for elective caesarean section? This Cochrane systematic review of ten studies (614 patients) concludes there is no difference with regards the rate of conversion to general anaesthesia or the need for supplemental analgesia. Hyperbaric bupivacaine may, however, give rise to a faster onset of block, though an adequately powered RCT is required to definitively prove this. In their editorial, Lucas and Bamber provide commentary on the recently published MBRRACE-UK Confidential Enquiry into Maternal Deaths and Morbidity. There is a new chapter on deaths attributable to anaesthesia and such deaths have dramatically decreased over the past 40-years. They argue that although the Confidential Enquiry reports should continue to be essential reading for the obstetric anaesthetist, other anaesthetists may find the report’s recommendations and messages have relevance to their own practice.

Elsewhere this month there is a description of a new retrograde trans-illumination technique for videolaryngoscopic tracheal intubation, a systematic review of dexamethasone for prophylaxis of postoperative nausea and vomiting, a study to determine the optimal programmed intermittent epidural bolus dose and a study of postoperative outcomes following cardiac surgery in non-anaemic iron replete and iron deficient patients.

Finally, there are two very important dates for your calendar. The first is the GAT Annual Scientific Meeting, which will be in Glasgow between the 4th and 6th July 2018. The second is the AAGBI Annual Congress Meeting, which will be taking place in Dublin between the 26th and 28th September. As ever, we will be taking our ‘How to publish a paper’ workshop to Dublin and running our ideas incubator, where selected authors of abstracts are invited to discuss how to turn their work into a full paper (Figure 2). Make sure you meet the Abstract deadline of May the 8th!

April2018_Figure 2

Figure 2 ‘How to publish a paper’ ideas incubator workshop from the AAGBI Winter Scientific Meeting, London, 2018

 

We hope you enjoy this month’s issue and we look forward to hearing what you think as each article is tweeted and made #FreeForADay!

M_Charlesworth                        A_Klein

Mike Charlesworth                 Andrew Klein

Trainee Fellow                        Editor-in-Chief

Socially accountable anaesthesia

It was reported in 2006 that anaesthetists in Uganda had the facilities to deliver safe anaesthesia for adults, children and pregnant women only 23%, 13% and 6% of the time, respectively. Furthermore, only 13 physician anaesthetists were in place for a population of 29 million. Thereafter, the AAGBI established a fellowship scheme with the primary aim to increase the number of physician anaesthetists in Uganda to 50. In this month’s Anaesthesia, the much-anticipated results of this initiative are presented, analysed and discussed. A mixed-methods approach (you can read all about qualitative research here) clearly demonstrates how a partnership between two professional organisations has profoundly changed healthcare in Uganda beyond the initial goal of improving human resource capacity. Unexpected benefits include greater access to surgery, anaesthesia and intensive care, and improved standards of training and patient care.

 

The accompanying editorial by Biccard and Green-Thompson describes how, in most low and middle-income countries, the demand for care far outstrips the capacity to provide it. There seems to be a global maldistribution of anaesthetic and surgical expertise, and part of the solution could be socially accountable education of future practitioners. They argue this should produce healthcare graduates who are responsive to the social needs of the local environment. Standards of care can be concurrently formed through partnerships and innovations, such as the Lifebox initiative (more about that here). Motivated learners can then be identified and supported through fellowships and emerge as socially responsive healthcare providers, able to address the limitations of a resource-limited environment. Socially accountable anaesthesia is therefore less about transference of a system into a country and more about supporting an existing system to thrive and become sustainable, and the trainee fellowship programme in Uganda is a remarkable example of this.

 

In patients undergoing general anaesthesia, does nitrous oxide decrease, increase or have no effect on the risk of accidental awareness under general anaesthesia (AAGA)? (Read all about the recent evidence related to AAGA here!) This Cochrane systematic review of 15 RCTs finds only three cases of reported awareness in the included literature. This, together with the poor quality of evidence meant it was not possible to draw meaningful conclusions, other than that the risk of awareness with or without nitrous oxide is unknown and included trials were not powered to measure awareness as a primary outcome. Is this yet another example of a question that cannot be answered with an RCT and where we may need to rely on observational ‘big-data’ analyses? Possibly….but more on that later!

 

Gastric ultrasound as a means to assess gastric content prior to, during and following surgery seems to be an increasingly popular area of study. For example, we have recently seen studies of the risk of aspiration through regurgitation of ingested blood in children undergoing ENT surgery, gastric emptying in healthy controls as compared with patients with end-stage renal failure and assessment of the gastric antrum before and after elective caesarean section. The first of two new such studies this month is an RCT of non-labouring pregnant women in the third-trimester randomised to one of six pre-determined volumes of apple juice. Ultrasound measurements following an 8-hour fast and immediately after the drink were taken, and a model for gastric volume estimation was derived. The resultant equation is the first mathematical model to predict gastric volumes in late pregnancy using bedside point of care ultrasound, and may one-day change the way perioperative care is delivered for such patients.

 

Additionally, a prospective observational study of pre-operative gastric ultrasound assessment in children undergoing elective surgery concludes it may provide more useful information than clinical assessment alone when aiming to predict the risk of pulmonary aspiration. Should we be using gastric ultrasound in our routine clinical practice to assess the risk of aspiration pneumonitis? Van de Putte and Perlas debate what constitutes a clinically insignificant gastric volume prior to anaesthesia, and conclude we may not be far from a simple, clinically-relevant bedside tool to help us accurately assess this risk. They discuss many issues pertaining to the timing of gastric ultrasound, how it should be performed and who should be doing it? There is lots here to discuss and debate and we would very much like to hear your thoughts.

 

When designing a study, one must decide which outcomes should be measured. For example, when comparing two analgesics, should we aim to demonstrate less pain, faster recovery or shorter length of stay? Say ‘less pain’ is selected, does this equate with lower pain scores, less morphine administered, longer time between requests, or should we use patient-related functional outcomes? A systematic review of outcomes in postoperative pain studies in children and adolescents finds a worrying lack of standardisation in outcome measurements that may prevent the pooling of such studies in a meta-analysis. The authors call for a core outcome set that may improve the quality of future trials and allow for more study-to-study comparisons. With regards outcome selection for systematic reviews, Heesen et al. suggest distinctions between primary and secondary outcomes should be abandoned. They also argue that clinically useful sub-group analyses should be reported regardless of whether or not it was planned to do so. Departures from the study protocol can be easily explained retrospectively in order to provide transparency.

 

This retrospective observational study in 1,478,977 patients concludes general anaesthesia is associated with a significantly higher risk of new-onset epilepsy, more so in patients with co-existing medical conditions and those suffering postoperative complications. ‘Big-data’ observational analyses are arguably more difficult to understand and interpret than an RCT, yet we are becoming more reliant on such studies to answer the questions RCTs cannot. (You can read all about the limitations and merits of retrospective observation here.) Thankfully, Ms Method Matters is on hand to guide us in our attempts to understand this finding. She concludes that when applying the results to a hypothetical Taiwanese population, there would be one more case of epilepsy for every 1111 undergoing general rather than neuraxial anaesthesia. Despite this context, there are certain limitations that cast doubt over our ability to comment on accuracy and clinical significance. Is the risk of epilepsy greater in those receiving general or neuraxial anaesthesia? Perhaps we will never know!

 

Elsewhere this month there is a RCT of different perioperative strategies for the management of patients with type-2 diabetes undergoing non-cardiac surgery, a RCT comparing recovery characteristics for patients receiving either sugammadex or neostigmine for reversal of neuromuscular blockade, a before and after observational study of a protocol or use of the C-MAC videolaryngoscope with a Frova introducer in pre-hospital rapid sequence intubation and an observational feasibility study of a new anaesthesia drug storage tray. Finally, with the abstract deadline for #GATASM18 fast approaching, we encourage you to send us your work! We enjoy reading your abstracts and many have the potential to become full papers. We hope you enjoy the March issue as much as we did, and we look forward to discussing each paper with you on Twitter. Don’t forget, each article is free for 24 hours on the day it is tweeted!

M_Charlesworth

Mike Charlesworth

Trainee Fellow

A_Klein

Andrew Klein

Editor-in-Chief

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