Blood – thicker than water?

Anaesthesia Blog, May 2016.

The first use of this phrase was probably in a German proverb (originally: Blut ist dicker als Wasser), Reinhart Fuchs by Heinrich der Glîchezære. By 1670, the modern version was included in John Ray’s collected Proverbs, and later appeared in Sir Walter Scott’s novel Guy Mannering (1815) and in Thomas Hughes’s Tom Brown’s School Days (1857). The June edition of Anaesthesia contains a number of articles that look at how thick blood actually needs to be and why this is important in the peri-operative period.

Anaemia is an increasingly prevalent condition, and has actually been described as an epidemic by the WHO. The Association of Cardiothoracic Anaesthetists (ACTA) undertook their first National Audit which is published here and describes how the rate of anaemia varies in different regions of the UK, from 23% to nearly double at 45%. The major finding of this study was confirmation of the association between anaemia and worse outcomes, and specifically that the lower the haemoglobin concentration is before surgery, the greater the chance of death is after cardiac surgery. In other words, thicker blood is good (except it seems if Hb > 150 g.l-1, which is also associated with increased mortality – is the blood too thick?).

Predicting which patients are more likely to bleed is one of the holy grails of peri-operative care, so that these high-risk patients can be targeted and actively managed. A group of authors used two point-of-care analysers to measure platelet function and found that a measurement performed soon after coming off bypass was best at predicting excessive bleeding. Tests performed at the start of surgery were not predictive, which is important as many manufacturers do recommend measuring at this point as a ‘baseline’, but this study suggests this may not be important. Also of interest was that patients taking pre-operative aspirin or clopidogrel were not more likely to bleed excessively, but anaemic patients were. Back to thicker blood is better!

Postpartum haemorrhage is the leading cause of maternal mortality globally, and this important study looked at the effect of platelets on major haemorrhage. Out of over 6000 deliveries over a one-year period, 356 (6%) women experienced moderate or severe haemorrhage, most commonly due to uterine atony, surgical bleeding or genital tract trauma. However, only 12 women required transfusion of platelets, which is much lower than in major haemorrhage due to trauma or following cardiac surgery, and this is a very interesting finding. Indeed, if the women had a normal platelet count before delivery and did not have placental abruption or other cause of consumptive coagulopathy, they had to bleed 5000 ml before requiring platelet transfusion. All this means that a fixed protocol including platelets is unnecessary for obstetric haemorrhage, and this is certainly relevant to clinical practice in every obstetric unit.

The final study that looked at bleeding was undertaken following major liver resection.  Not many anaesthetists look after these patients in the peri-operative period, but the authors finding that most patients were in fact less likely to bleed (were hypercoagulable – thicker blood?) after surgery, as measured using point-of-care tests, is relevant to all anaesthetists. This implies that instead of bleeding, most patients are at increased risk of thrombosis postoperatively, despite major surgery/transfusion, and that laboratory tests are in fact misleading during the immediate postoperative period. This would mean that prophylactic anti-thrombotic agents such as low-molecular weight heparin should be started earlier, and that laboratory tests should be replaced by point-of-care tests, a fact which is emphasised in this editorial. It really seems to me that the time has come to use point-of-care tests more widely, even once surgery has finished.

To finish off this blog on blood and bleeding, the new AAGBI Guidelines on transfusion have just been published, and they replace three previous guidelines on blood component therapy, massive haemorrhage and red cell transfusion. They will appear in the journal next month and will be sent round to every anaesthetic department as well as the Chief Executive of every NHS Trust in the UK. Read them yourself and see if blood really is thicker than water, or at least how important it is in the peri-operative period.

 

 

Andrew Klein

Editor-in-Chief

Its not what you do it’s the way that you do it.

Anaesthesia Blog, April 2016.

Ella Fitzgerald, Little Richard and Bananarama all famously sang “It ain’t what you do it’s the way that you do it”, and the May edition of the journal reinforces this in several ways.

The first example of this is a fascinating and shocking editorial about sugammadex that has important lessons for all of us who undertake (or take part in) research, audit and service evaluations in our institutions. The authors describe how they determined that a proposed study was a service evaluation and registered their study with their institution, but did not seek formal ethical approval, as advised under recommendations for service evaluations in the NHS, and did not gain patient consent or even discuss participation in the study with their patients. After ENT surgery, they exchanged the tracheal tube for a laryngeal mask, and then administered sugammadex to reverse neuromuscular blockade; the first two patients in their study then developed sudden and dramatic airway obstruction. The study team decided to investigate this further by performing fibreoptic endoscopy through the laryngeal mask on the next three patients and saw that the vocal cords were completely closed following sugammadex administration, a totally unexpected finding that had not been described in the literature before at this point. However, the key point was that they didn’t discuss this and other protocol changes with anyone else, namely their institution or more importantly, the patients themselves. They also didn’t report the adverse events locally. The Editor-in-Chief at the time of submission of the resulting article (Professor Yentis) contacted the authors, and eventually the local ethics committee, and a formal investigation into their ethical conduct resulted. Finally, the patients who took part in the study were contacted, and all agreed that data arising from the study could be published.

There are numerous lessons to learn. What someone thinks is a service evaluation or audit may be much closer to a research study in the opinion of others, and Professor Yentis, in his accompanying commentary, argues that study protocols should be discussed with an ethics committee in many more cases, if not routinely, and prospective patient consent sought. The journal receives numerous submissions where there is doubt about the ethical conduct of the study, and one of the commonest questions I am asked is “Do I need formal ethical permission?” Perhaps the new NHS system of all applications for studies in England (including audits and service evaluations) needing to apply for HRA approval (see http://www.hra.nhs.uk/research-community/applying-for-approvals/) will sort this conundrum out once and for all? From the journal point of view, we expect to change our guidelines to authors and insist that HRA approval has been granted before starting any study from April 2016 – more about this to follow.

What about the actual findings of the work of these authors? Well, these are interesting and quite novel. The adverse effect of sugammadex, namely that it may lead to airway obstruction if given to patients who do not have a tracheal tube in situ, due to vocal cord closure, is important and should be communicated to the anaesthetic community who have started to embrace sugammadex into their more mainstream practice recently, hence the decision to publish the account of this study as an editorial. The way the authors conducted the study may have been flawed, without formal ethical approval or patient consent, but the lessons from their conduct and work still need to be learnt.

 

There has been much debate in the literature about anaesthetic technique for surgery following fractured neck of femur, between general and spinal anaesthetics (with or without nerve blocks). An excellent article, which analysed the data from over 16,000 operations carried out in 2013 as part of the Anaesthesia Sprint Audit of Practice (ASAP-1), is published in this month’s journal. The overall message I took from this article was that the type of anaesthetic technique (GA or spinal) did not affect mortality, but how, and with what degree of care, especially with regards to blood pressure, the anaesthetic was provided, did matter. On one hand, this is not that surprising – we know that anaesthesia is a craft specialty, and how you give an anaesthetic is important, as demonstrated so eloquently in this article. On the other hand, the lack of a difference between the two major choices of technique (at least with respect to mortality), is surprising, as so many anaesthetists have polarised views one way or another. The question about whether the study design may have affected the findings is also an important one, as discussed in the accompanying editorial. The argument over the relative advantages and disadvantages between large observational studies, such as ASAP-1, and randomised controlled trials (the current so-called gold standard for level of evidence) will no doubt rage on, but in the meantime, the evidence we have is that conduct of anaesthesia is more important than actual technique with regards to mortality after fracture neck of femur. In other words, how you give your anaesthetic, not what anaesthetic you give.

Finally, the first guidelines for safe vascular access are published in May’s edition of the journal. This lists some very important recommendations that I believe will shape our practice with regards to vascular access for years to come. Vascular access, be it peripheral, central or arterial, is the most common invasive procedure carried out in hospitals, and if carried out with care and attention, and with meticulous aftercare, is safe. These guidelines recommend more widespread/earlier use of ultrasound, more formal training and supervision, better systems (including specific policies regarding safety and proficiency), all with the aim of improving safety, effectiveness and timeliness of all vascular access. Remember, it’s the way that you do it (and look after it, in this case), that’s important.

 

 

Andrew Klein

Editor-in-Chief

The first Anaesthesia blog – April edition

This is the first Anaesthesia Blog, which will mostly talk about the new April edition of the journal. The reason for the discrepancy in months is that the following month’s edition is published online two weeks or so before it is posted out to AAGBI members and print journal subscribers. The idea of the new journal Blog is to direct you to interesting, topical or controversial articles, editorials, reviews, guidelines and letters.

Deciding what to read as a clinician is increasingly hard, as more and more journals seem to spring up each month, and thousands of anaesthetic, intensive care, pain or peri-operative medicine articles are published each year, seemingly continuously. Each journal needs a raison d’être, and ours is to publish clinically relevant, important and novel literature. As a UK-based journal, we have traditionally published a lot of papers from the UK, but that is changing, as more and more submissions arrive from upcoming powerhouses in the research world like China and Korea. Despite all the changes over the last few years, we strive to improve our standards year by year, and to be the best most clinically relevant journal out there.

The new April edition of the journal focuses on a number of sub-specialist areas, but also contains a review of capnography for sedation, which is likely to be relevant to all anaesthetists. The authors, having examined six trials containing 2524 participants, concluded that the use of capnography reduced hypoxaemic episodes. However, they also commented that the quality of the evidence was poor and that this was an area ripe for future research, which was re-iterated by Professor Cook in his accompanying editorial. This discusses what progress has been made towards much more widespread use of capnography outside of the operating theatre. I have certainly noticed that capnography is now routinely used in the ICU and during recovery from anaesthesia, and also for transferring patients around the hospital, but it is yet to be used more widely for sedation, and I agree that further evaluation for such use is urgently required.

Regional anaesthesia is a burgeoning sub-specialty of our practice, and there are a number of innovative and important articles in this issue. The first reports on 1505 patients who received continuous interscalene analgesia at home via a ultrasound-guided catheter. The authors managed to get around the myriad of logistical and safety concerns related to ambulatory administration of the block, and the catheters themselves were taken out by the patients. They reported that 27% of patients reported mild dyspnoea, 13% hoarseness and 7% dysphagia. Twelve percent sought medical advice and 2% reported technical issues with the pump or tubing. The relevance of the excellent large series to practice in other institutions and healthcare settings are described in an accompanying editorial, aptly entitled interscalene catheters – should we give them the cold shoulder? Finally, the use of dexamethasone, either intravenously or added to the local anaesthetic mixture, is examined in a randomised controlled trial of interscalene blocks. The authors concluded that giving dexamethasone intravenously at a dose of 8mg was just as good as giving it perineurally, and probably safer.

Pain relief in the emergency or trauma setting is a controversial subject, and an age-old anaesthetic drug in a new formulation, methoxyflurane, was tested in patients having burns dressings changed. The authors reported a 97% success rate of methoxyflurane analgesia to facilitate these procedures, but noted that limitations included maximal daily and weekly doses, and uncertainty regarding safety in patients with pre-existing renal disease.

The final review I am going to mention concerns radiation safety, which examined a number of studies that showed that at 1.5 m from the source of radiation, anaesthetists received almost no radiation, and that the radiation doses at this distance were often at the limits of the sensitivity of the measuring dosimeter. Does that mean we can take our leads off in theatre as long as we sit more than 1.5m away? I can’t see that happening but in an evidence-based environment perhaps it should?

Teamwork and communication are both buzzwords for all peri-operative physicians, and of vital importance to our everyday practice. Examining different ways of communicating and evaluating their effectiveness is quite a new area of research, and we are seeing more and more submissions to the journal about this subject. This month sees the publication of an excellent study that examined the use of cognitive aids during a simulated intra-operative emergency (anaphylaxis). Team performance was improved by the use of a cognitive aid, and a linear type of aid had the greatest effect. This study should help the design of future cognitive aids, be they on paper or on our smartphones or other innovative technology, and the study methodology was very well-planned and executed to allow the authors to answer their questions about how teams work best.

My final word is a look into what is coming up in the journal. Next month we will feature a lesson in the ethics of clinical trials, which makes scary reading and should prompt us all to re-examine how we categorise research, audits and service evaluations, a thorny issue. Next month will also see the publication of a trial comparing patient-administered with nurse-administered oral analgesia after caesarean section, which could mean the end of the drug round. In April, we will be holding our first Twitter-moderated ‘Chat’ about an interesting new article on analgesia for patients carried on emergency medical evacuation helicopters.

Andrew Klein, Editor-in-Chief, Anaesthesia