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Lessons from Camels. EMJ Blog.

8 Oct, 16 | by scarley

EMJ Blog

Life long learning and developing is vital for the good ED practitioner,  treatments change, pathologies change and even opinions change over months and years, and we on the front line must continually adapt and change with them.

To highlight the importance of this I would like to tell you a story. It is a story about a camel.

In 2006 palaeontologist Natalia Rybczynski was tramping through the artic wastes in the far North of Canada (as you do) as she came across some unusual grey rocks. Now personally I would have stubbed my toe on these rocks, cursed and wandered off in search of a hot chocolate, but being a shrewd and observant palaeontologist Natalia saw that these were fossils of a type she had not encountered before. She collected these, and returned over the next few years, managing to find around 30 fragments of what appeared to be a fossilised tibia(1).

Subsequent super clever collagen fingerprinting techniques revealed that these remains amazingly were from a hitherto undiscovered giant camel. Now this raised some interesting questions.  Camels are sublimely adapted to the hot and dry desserts, with their large spoon-like feet for walking on sand, and large fat filled hump meaning they can survive for longer without food. The function of having all your fat reserve in a single hump also means that you can do without the surrounding layer of adipose tissue, allowing these animals to dissipate heat easily in their hot climates.

So how could these hot weather specialists have survived in the arctic, where temperatures often plummet deep into the negative figures. (I promise I am getting to the medicine!)

To get the answer we need to re-examine what we think we know about camel’s adaptations, and take them out of the context we always find them in (the desert). For example, those wide flat feet could easily be adapted to snow, as well as sand, in fact it is likely they initial evolved to walk in soft snow and then subsequently were found to be of an advantage in the desert sands. That hump with the fat reserves would be vital when trying to survive in a place were for 6 months of the year there is darkness and nothing grows.

We have thought of camels as hot weather beasts for hundreds of years, and then all of a sudden someone finds a few lumps of rock in the arctic that causes us to completely reconsider what we think we know, and to have to think in new ways to explain things we thought we had sorted.

The recent example from the field of medicine is the FEAST trial (2) We have believed for many years that fluids were the mainstay in the treatment of severe sepsis and septic shock, and then someone comes along with a brilliant study that casts doubt on this assumption and causes us to have to rethink what we thought we knew. The FEAST trial shows us that we do not understand pathophysiology of septic shock as well as we think we do. As good clinicians we should accept this and try to explain the apparent paradoxical findings. The authors to their credit, offer the explanation that fluid boluses may cause damage through reperfusion injury, effecting pulmonary compliance or myocardial function. The FISH (Fluid In SHock) trial is currently running in hospitals across the UK to follow-up FEAST and see if we should be changing our practice.

As clinicians we have a duty to continually question what we think we know, and to search for better and more efficient ways of treating our patients. The doctor who clings to dogma and does things a certain way, because they have always been done that way is doing his patients a disservice and indeed could be putting them in harms way.

We will never know everything, and what we believe we know now will change over the course of our careers and even our lives, so I would urge everyone to learn the lessons of the giant camels, and never stop questioning what we think we know, to enable us to always do the best possible for our patients.

Thanks
Chris Arrowsmith

ST4 Emergency Medicine
Current Paediatric Intensive Care and Acute Retrieval Clinical Fellow, Bristol

image1
References

1. Rybczynski N, et al. 2013. Mid-Pliocene warm-period depostis in the High Arctic yield insight into camel evolution. Nature Communications, 4:1550

2. Maitland K, et al and the FEAST Trial Group. Mortality after Fluid Bolus in African Children with Severe Infection. N Engl J Med. 2011 May 26.

What’s your target BP for ruptured abdominal aortic aneurysm?

29 Jun, 14 | by scarley

Untitled design(5) copy 2

 

A couple of years ago I was very (very, very) peripherally involved in an RCT investigating the management of ruptured abdominal aortic aneurysm. The IMPROVE trial was well designed and reported it’s results in 2014. The abstract is shown below, and I must admit that to my surprise there did not appear to be a definable advantage to endovascular repair.

Anyway, this post is not about the trials results per se, rather we received a comment from Prof. Janet Powell on behalf of the trial investigators that may have relevance for those of us in emergency and critical care medicine. One of the great advantages of large trials is the ability to look through data to see whether other themes and associations become apparent and this is what the trial team have done. Such data analysis has risks, but it can be an excellent way of generating hypotheses for future research, and observational data can also help us stop and think about current practice.

I digress. Read the letter from Janet below and then share your thoughts. As an emergency physician this observation raises a myriad of questions about data, analysis, resuscitation targets, association vs causality etc. and whenever I start thinking I know I’m getting better. So please, read, think, learn and please debate. Janet asks how we can work together to resolve and explore these results and surely that’s an offer that the EM and surgical communities should grasp.

vb

S

 

Blood pressure targets for the elderly with bleeding and vascular emergencies

The IMPROVE trial is the largest randomised trial of a strategy of endovascular repair versus open repair for ruptured abdominal aortic aneurysm, with over 600 patients [1]. Nearly all these patients started their care pathway in the emergency department and detailed evaluation of this large cohort of patients has raised some discussion points relevant for those in emergency care.

When we started this trial, we recommended that patients were managed with fluid restriction and hypotensive haemostasis, with systolic blood pressure targets of 70-80 mm Hg, to prevent further bleeding and optimise outcomes. These recommendations were based on emergency care guidelines for patients with abdominal trauma and the opinions of some leading vascular surgeons [2,3]. Hindsight is a wonderful thing. The patients we enrolled had an average age of 76.7 years: were these blood pressure targets far too low for this age group who were likely to have other cardiovascular disease and high cardiovascular resistance?

Cohort analysis has shown that there was a linear relationship between lowest systolic blood pressure and mortality (Table 1) and suggests that in these patients a blood pressure target of 100 mm Hg might save more lives. Lowest systolic blood pressure was directly related to outcome in a linear fashion, with each 10 mm Hg increase translating into a 13% relative improvement in the odds of survival to 30-days [4]. 30-day mortality rates of <30% were only achieved in those in whom the lowest blood pressure was 100 mm Hg or more.

Screenshot 2014-06-29 07.25.24

Management of other aortic conditions, particularly aortic dissection, may similarly be disadvantaged by unrealistic blood pressure targets. For aortic dissection the rapid blood pressure lowering to <100mm Hg, which is recommended [5], comes mainly from evidence in turkeys.

How can we work together to get the evidence for appropriate blood pressure targets for the elderly population with bleeding and other vascular emergencies? The current observational evidence is not sufficient and the question needs to be addressed in one or more randomised trials.

Janet Powell for the IMPROVE trial investigators

 

References
1 Endovascular or open repair strategy for ruptured abdominal aortic aneurysm: 30 day outcomes from IMPROVE randomised trial IMPROVE trial investigators BMJ 2014;348:f6771
2 Joint Royal colleges Ambulance Liaison Committee. Ambulance Service Clinical Practice Guidelines; 2006. www.jrcalc.org.uk/guidelines.html‎ [accessed 1 September 2013].
3 Mayer D, Pfammatter T, Rancic Z, Hechelhammer L, Wilhelm M, Veith FJ et al. 10 years of emergency endovascular aneurysm repair for ruptured abdominal aortoiliac aneurysms: lessons learned. Ann Surg 2009; 249: 510–515
4 Observations from the IMPROVE trial concerning the clinical care of patients with ruptured abdominal aortic aneurysm. IMPROVE trial investigators Br J Surg 2014
5 The Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure: the JNC 7 report. Accessed March, 2014 at www.nhlbi.nih.gov/guidelines/hypertension/jnc7full.pdf

 

So you have your invitation. Get in touch with the IMPROVE team to discuss, share and explore this observation.

 

vb

 

S

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