September 2017 – #TheAnaesthesiaBlog

This month in Anaesthesia sees yet another possible victory for sugammadex as compared with neostigmine for the reversal of rocuronium-induced neuromuscular blockade. Laryngeal microsurgery is an example of a short surgical procedure where surgeons request deep neuromuscular block yet complete reversal prior to emergence and extubation. (Of course, trans-nasal rapid insufflation ventilatory exchange [THRIVE] is an exciting alternative these days – but that debate is for another time.) This presents an obvious dilemma for the anaesthetist, as intubating, operating and extubating conditions are traded off against emergence and recovery time. Choi et al. randomly allocated 44 patients to receive either high-dose rocuronium (0.9 mg.kg^-1) with sugammadex reversal (4 mg.kg^-1) or low-dose rocuronium (0.45 mg.kg^-1) with neostigmine reversal (50 μg.kg^-1 with 10 μg.kg^-1‑ glycopyrrolate) for patients having laryngeal microsurgery. Unsurprisingly, onset time, level of block, operating conditions and recovery time (2.1 vs 9.9 minutes) were all superior in the sugammadex group. The clinical efficacy and versatility of sugammadex is substantial yet its financial cost remains a major barrier preventing widespread use. The insightful accompanying editorial by Bailey asks when it is appropriate to use sugammadex and whether we should be using it more. The general message seems to be that there are certain circumstances where it is most definitely appropriate, but neostigmine is by no means dead……just yet.

The ethics of airway research have been extensively debated in recent issues. This month, Cook et al. provide discourse in relation to ‘consensus on airway research ethics’ (CARE) published in Anaesthesia. The issue seems to be whether or not the consensus guideline is necessary at all and how such research can reflect an increasingly complex workload that includes more ASA 3+ patients with difficult airways. The ultimate question Cook et al. ask is: how generalisable is manikin-based airway research? The authors of the guideline provide a counter opinion in the correspondence section and argue that rather than an all-encompassing mandatory protocol, the CARE guidelines were designed to provide guidance and to promote informed discussion in the field of airway research. What do you think? Send us a letter through our correspondence website!

There are three further airway papers of interest this month, all in relation to paediatric anaesthesia. Firstly, Mihara et al. performed a network meta-analysis* of various types of supraglottic airway device in children (Figure 1).

Figure 1. Network graph for insertion failure at ﬁrst attempt. The size of the blue node represents the number of patients included in studies featuring that device. The thickness of the lines connecting the nodes is proportional to the number of head-to-head randomised controlled trials in each comparison. The numbers next to the connecting line indicate the number of randomised controlled trials. Where a number is absent, there is only one trial reporting that comparison. airQ-SP, self-pressurised air- Q; Ambu-AG, Ambu AuraGain; Ambu-i, Ambu Aura-i; Ambu-o, Ambu AuraOnce; c-LMA, laryngeal mask airway Classic; Cobra, Cobra perilaryngeal airway; f-LMA, ﬂexible laryngeal mask airway; LT, Laryngeal Tube; p-LMA, Proseal laryngeal mask airway; s-LMA, Supreme laryngeal mask airway; SLIPA, Streamlined Liner of the Pharynx Airway; u-LMA, laryngeal mask airway-Unique

They identified 65 trials with 5823 patients assessing 16 different supraglottic airway devices to determine oropharyngeal leak pressures, first attempt success, blood-staining risk and device failure. They reported that LMA®-Proseal and i-gel™ have high oropharyngeal leak pressures and a low risk of insertion trauma, as previously suggested, however the risk of device failure with i-gel™ is somewhat higher. Nevertheless, before translating this study into clinical practice it may be worthwhile reading the accompanying editorial by Nørskov et al. Scientific evidence, important though it is, forms only one piece of the puzzle when choosing whether to adopt a new airway device into clinical practice.

How does the UK fare in terms of anaesthetic research output as compared to other G-20 countries over the last 15 years? As revealed by Ausserer et al., although the absolute number of anaesthesia articles (2564 from the UK in 2011-2015, if you’re wondering) is steadily increasing, there has been a considerable lack of relative growth from many developed countries against a backdrop of an 11 and 9-fold increase for China and India respectively (Figure 2).

Figure 2. Percentage distribution of selected G-20 countries regarding published articles. Others not shown (ARG, AUS, BRA, CAN, FRA, IDN, ITA, KOR, MEX, RUS, SAU, TUR, ZAF) changed only by 1% or less. EU* excludes the EU countries otherwise shown in this figure

Of course, our Canadian cousins published the most articles per million inhabitants, which is testament to their research systems. But is this a cause of concern for the UK, or is it that output, as measured by the quantity of publications, only tells part of the story?

The early withdrawal of treatment for out of hospital cardiac arrest (OOHCA) victims and those with a devastating brain injury is never straightforward as we cannot predict the probability of survival with absolute precision. Yet there is evidence and even an expert consensus-based pathway for OOHCA victims that advises against prognostication during the first 72 hours after return of spontaneous circulation. Manara and Menon present a compelling argument for translating these practices to the care of those patients who have suffered a devastating brain injury. This would offer a number of benefits including the survival of a small number of retrievable patients, permitting families time to come to terms with a catastrophic event, allowing informed withdrawal after an appropriate interval, offering families the opportunity for carefully considered organ donation, and supporting development of the evidence base for clearer prognostication and decision making in the management of patients. As we have seen before, perhaps we need to stop the concept of therapeutic nihilism?

Elsewhere in the October edition there is an interesting comparison of oral chloral hydrate and intranasal dexmedetomidine to facilitate CT scanning in children, an evaluation of the Minto TCI model during cardiopulmonary bypass, an RCT comparing different analgesic approaches for postoperative pain following caesarean section, and the description of a novel approach to thoracic paravertebral block (Figure 3).

Figure 3. (a) Ultrasound transducer position and needle insertion site for mid‐point transverse process to pleura (MTP) block technique. (b) Ultrasound image and schematic demonstrating the injection point for the MTP technique. SCTL, superior costotransverse ligament; PVS, paravertebral space; i/c muscle, intercostal muscle; m, muscle; TP, transverse process.

All this and much more in a bumper edition of Anaesthesia to keep you feeling bright as Autumn draws in and the nights get longer. Enjoy!

*A network meta-analysis is a systematic review where several interventions are directly and indirectly compared in terms of their efficacy.

Mike Charlesworth

Trainee Fellow, Anaesthesia (17-18)

Kariem El-Boghdadly

Trainee Fellow, Anaesthesia (16-17)

Andrew Klein

Editor-in-Chief

Post art: Kariem El-Boghdadly

“Resting is fitness training”

–Jenson Button

The well-documented struggles trainees have suffered recently are compounded by training requirements and clinical workload. So how do the pressures of modern day training affect physical, psychological and social well-being? McClelland et al. looked to answer this question by conducting a national survey of trainees and assessing the impact of night shifts on fatigue. Over half of all trainee anaesthetists responded, with an even spread of training grades. After finishing a night shift, nearly half of the respondents needed to drive on the motorway to get home, and nearly a fifth travelled for more than 60 minutes. This is compounded by the fact that 84.2% of respondents claimed to be too tired to drive home after a night shift, and more than half having experienced either an accident or a near miss (including falling asleep at the wheel) on their post-nights homeward journey. Less than a third of trainees were aware of rest facilities following night shifts, and if they were available, they could cost up to £65 a shift. Night shifts commonly led to sleep disturbance and the use of substances such as caffeine to mitigate the adverse effects of their fatigue. Finally, the study authors found that personal relationships, physical health, psychological well-being, the ability to do the job and the ability to manage exam revision and projects were all negatively affected by fatigue in more than half of respondents. All in all, McClelland et al. have reported highly concerning adverse effects of the working patterns of anaesthesia trainees.

Michael Farquhar has followed this up with a telling editorial, questioning the ‘hero attitude’ that trainees have been encouraged to develop, and describing the measures his institution and specialty have taken to mitigate the worrying results reported by McClelland et al. These include breaks that are not voluntary, mandatory training in sleep hygiene, and changing culture to accept that self-care is not ‘an optional luxury.’ We should no longer believe that we as doctors can fool physiology, particularly at a time when morale is plummeting, and burnout is on the rise.

In a very different study, Suehana Rahman et al. present a much-needed review of the literature pertaining to patient medical alert identification (ID) tools, something that seems to have slipped under the regulation radar thus far. Medical ID tools can be in the form of jewellery, body art such as tattoos, personal devices, medical ID cards, or other forms such as key rings or bag tags (Fig. 1).

Figure 1.png

Figure 1. (a) MedicAlert wristband and (b) bracelet worn over the traditional ‘pulsepoint’ location

They could present a range of material, including allergy status, information of medical conditions the ID carrier suffers from, pharmacotherapy, and contact details of next of kin. The authors conducted a systematic review of medical databases as well as a Google search, and found four reports of adverse events due to medical alert jewellery, and 32 online vendors of medical alert jewellery, with no evidence of any standards and minimal involvement of physicians. There was no evidence reported that medical IDs ‘work’ or are even safe. With little guidance available, the authors proposed four principles:

Medical IDs should be substantiated by messages conveyed by patients
In unconscious patients, healthcare workers should not conduct ‘disproportionate searches’ for medical IDs
If medical IDs are discovered in unconscious patients, staff should interpret the information rationally and proportionately
Conscious patients should convey all relevant information directly and not rely on the information in IDs alone

Could these proposals be the start of a new era of international standardisation of medical alert IDs?

Contrary to this scarcely-researched question, Stens et al. reported another interesting study, fuelling the ongoing debate regarding the value of intra-operative cardiac output monitoring on perioperative outcomes. They assessed the addition of pulse pressure variation and cardiac index to arterial blood pressure monitoring via the non-invasive ccNexfin device in patients undergoing general surgery. This multicentre, double-blinded trial randomised 244 patients to either be monitored with just continuous arterial pressure, or adding pulse pressure variation and cardiac index monitoring to standard arterial pressure monitoring and managing fluid therapy according to a specified algorithm. They found that there was no difference in 30-day complications, total fluid and blood products infused, fluid loss and blood loss, or return to mobility. Notably, fewer patients in the control group needed vasopressors. So, does this add further fuel to the fire against goal-directed therapy with cardiac output monitoring? Or does this simply suggest that the Nexfin device does not reliably contribute to improved patient outcomes? Only time will tell.

Another question of time relates to pre-operative fasting guidelines. We mandate a six-hour fast for solids and two hours for clear fluids, but what is really going on in the stomach in emergency patients after this duration of time? Dupont et al. performed gastric ultrasound assessment, determining the volume of the gastric antrum, in 263 patients who were starved for > 6 h and having emergency surgery (Fig. 2).

Figure 2. The distribution of gastric volume estimated for 263 participants before unplanned surgery, after at least six hours of fasting

They found that more than a third of patients had volumes consistent with unstarved stomachs, and the size of the antrum was associated with BMI and the pre-operative consumption of morphine. Moreover, one patient in their cohort suffered from pulmonary aspiration, yet this patient did not have a gastric antrum that suggested a full stomach. The data presented by Dupont et al. suggests that the duration of pre-operative starvation may not be related to gastric antral area, and thus volume, in emergency surgery – so what does this mean for aspiration risk without rapid sequence induction in all emergency surgery patients?

On the subject of food, there is plenty of food for thought from novel, thought-provoking and practice-changing papers published in the September edition of Anaesthesia. The dynamic research group working with the NIAA and The James Lind Alliance Priority Setting Partnership explored the difference in anaesthesia and critical care research priorities between clinicians, carers and patients. Despite all groups prioritising patient safety, they found a discrepancy between patients and clinicians – the former favouring patient experience while the latter favouring clinical effectiveness. A surprising result? Perhaps not. However, in another paper published this month, Berning et al. surveyed nearly 500 patients to compare the effect of quality of recovery from surgery on patient satisfaction and they found little correlation. So how is patient satisfaction, experience, quality of recovery and clinical effectiveness all linked, and what is most important? Expect a flurry of research trying to answer this question in the coming years!

Also in the September edition, Chen et al. reported an increased success rate of double-lumen endobronchial intubation using a novel wireless videostylet, the Disposascope® versus conventional intubation (Fig. 3), Shah et al. found that psoas muscle mass is associated with mortality following elective AAA repair, and Pillai et al. discovered that Luer and non-Luer spinal needles are equally as strong! All this and much more in one of the most diverse editions of Anaesthesia this year – eat, drink and sleep well!

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