Occam’s razor

Occam’s razor (or the law of parsimony) is a problem-solving principle attributed to William of Ockham (c. 1287–1347), who was an English Franciscan friar, scholastic philosopher and theologian. The principle states: ‘other things being equal, simpler explanations are generally better than more complex ones’. This month’s blog looks at simple interventions and principles, and whether Occam’s razor hold true in our practice.

Paracetamol – great drug, right? I swear by it, and dispense it liberally, both at home and in the operating theatre and the intensive care unit. A simple study with a very simple hypothesis is published in October’s edition of the journal, comparing oral (enteral) with intravenous (parenteral) paracetamol in ICU patients. Patients who received the intravenous formulation were much more likely to suffer hypotension and require vasoconstrictors to ameliorate this. Wow – so paracetamol is not as harmless as we all think? If one off doses can cause hypotension like this should we still be giving it at all in our ICU patients, or should we only be giving it enterally (presumably via the NG tube – hypotension still occurred but less commonly)? Maybe this simple, effective drug is not the panacea? A very interesting study I am sure you will agree.

What about teaching tracheal intubation to novices? We have traditionally taught the use of the Macintosh laryngoscope first, but will they learn it and remember it better if they are taught with a videolaryngoscope? Actually, perhaps not – this excellent study studied a group of medical students and looked at skill retention. This study showed that the students learnt how to use the Macintosh, A.P. Advance™, C-MAC® and Airtraq® laryngoscopes equally well at first, but one month later, they seemed to have retained the skill-set required for laryngoscopy significantly better with the Macintosh and Airtraq laryngoscopes. In this instance, simpler seems to be easier to pick up again and get to grips with more quickly, a salutary lesson.

This month, we also publish an interesting systematic review of the effect of propofol compared with inhalational anaesthesia on postoperative outcomes including pain. This well-conducted rigorous review found that patients who received total intravenous anaesthesia with propofol did indeed have reduced pain scores 24 hours after surgery, although the effect size was quite small. But, it also confirmed that postoperative nausea and vomiting was markedly less common. Is this enough to make you switch your technique to TIVA? Maybe not, after all these are not really important outcomes like mortality, but will we ever recruit enough patients to see a difference in mortality if there was one – I doubt it. So what are we waiting for, or do we just not believe there is actually a difference? Perhaps it is simpler to believe the opposite, that inhalational and propofol are much of a muchness for maintenance of anaesthesia and we are not convinced either way yet.

Finally, our statistics article explains why odds and risks (and other numbers) often confuse things, both for researchers and for readers (consumers). Why do we like to use complicated statistics to describe things, when simpler explanations are often possible if not preferable? If you, like me, don’t know the difference between the odds of something and the risk of the same thing, then read it and learn – I did, and I am off to put a bet on the 2-30 at Newmarket…


Andrew Klein


The Olympics for anaesthetists

Well, that’s it for another four years. Months and years of preparations, and in the end it came down to five days of non-stop action and one night of celebration, then everyone goes home. This is the week that was the World Congress of Anaesthesiologists in Hong Kong, and what a good one it has been. I am going to give you a bit of a flavour of the event and how this journal fared at the pinnacle of our professional calendar of conferences.

The whole event was organised by Mike Irwin, Professor at Hong Kong University and one of the editors of Anaesthesia. Siu Wai Choi, the statistical advisor to this journal was also ever-present, coaching us to rise above any mathematical missed passes. However, John Carlisle, another editor of the journal, was the real star turn when he shared the podium with Steve Shafer (ex Editor-in-Chief of Anesthesia and Analgesia @stevenlshafer) and Nathan Pace (from the University of Utah and Senior Statistical Advisor at Cochrane). John presented his initial analysis of Fujii that led to the retraction of 183 publications and his undisputed Number 1 position on the Retraction Watch Hall of Shame (@RetractionWatch). He then presented the rationale for Monte Carlo simulation and his updated analysis – the Carlisle Method – which he announced he has now applied to all randomised controlled trials published over the last 15 years in this and seven other journals. Interestingly, another author has come to light after the application of the Carlisle Method following the submission of a suspicious manuscript to another journal, and this further analysis previewed at the World Congress will be published shortly in Anaesthesia.


One of my own personal highlights was the sight of the delegates queuing patiently to get hold of souvenir USB sticks containing the China Special Edition and World Special Edition of Anaesthesia produced especially for the Congress, and you can see these special editions yourself on our website by clicking on the links above. I also particularly enjoyed crossing the city to Hong Kong University to present a workshop to upcoming biomedical researchers on what and how to publish. The researchers packed the room and posed many questions about publication, research and the world of journal intrigue and peer review.



There was great interest at the Congress in several recently published articles. A Korean group presented their findings about complications during subclavian central venous catheterisation, and their conclusion that a wire-through-needle technique is safer than a catheter-over-needle technique should finally put to bed the longstanding debate about the two techniques. There were several fiery debates and discussions about routine or otherwise use of dexamethasone, with the presentation of data about the inescapable rise in glucose concentration associated with its use in diabetics and non-diabetics. Finally, novel regional blocks were much in evidence, and particularly the serratus anterior plane block, which was dissected in detail.

To finish up, a bit about the final night of celebration. A crowd of us were shown the sights of the harbor from the top deck of a boat, followed by a seafood dinner and even one or two local beverages. I understand that a number then went on to do a crawl around the top 10 rooftop bars of the city, but myself, I was tucked up in bed ready for the Closing Ceremony. I am sure everyone is looking forward to the next Olympics in Prague in 2020 – I certainly am.


Andrew Klein