Tag Archives: prehospital

HIRT – Studying a Non-Standard System that Ended up as Standard

March 21, 2015 careflightcollective 17 Comments

There’s always a bit of extra reflection you can’t include in the discussion of a research paper. Dr Alan Garner reflects more on some of the challenges of doing research in prehospital medicine.

The main results of the Head Injury Retrieval Trial have now been published on-line in Emergency Medicine Journal. We have paid the open access fees so that the results are freely available to everyone in the spirit of FOAM. This was an important study that was eagerly awaited by many clinicians around the world.

The summary from my point of view as the chief investigator: an enormous opportunity wasted.

It is now nearly ten years since we commenced recruiting for the trial in May 2005. Significant achievements include obtaining funding for a trial that was ultimately to cost 20 million Australian Dollars to run. I am not aware of another prehospital trial that has come anywhere close to this. Hopefully this is a sign that prehospital care is now seen as worthy of the big research bucks.

In the subsequent ten years world events have helped to drive increasing investment in prehospital trauma research, particularly conflicts in Iraq and Afghanistan and the perception that there were many preventable deaths. The US government has become a big investor in prehospital research that might lower battlefield mortality. The Brits on the other hand typically made some assumptions based on the evidence they had and got on with it. Higher levels of advanced interventions during evacuation as exemplified by the British MERT system in Afghanistan seem to be associated with better outcomes but the evidence is not high quality.

I am the first to acknowledge that randomised trials are inherently difficult when people are shooting at you. Most prehospital care is not quite that stressful but there remain significant barriers to conducting really high quality prehospital research. Taking the evidence you have and getting on with it is a practical approach but it is not a substitute for meticulously designed and executed high quality studies. Such studies often disprove the evidence from lower level studies. We all bemoan the lack of good data in prehospital care and recognise the requirement for better research.

When you’re only left with signals

The Head Injury Retrieval Trial taken in this context really is an opportunity wasted. There is a strong signal in the as-treated analysis of unconscious trauma patients that there is a significant difference in mortality associated with physician prehospital care. The Intention to treat (ITT) analyses was not significant however.

The potential reasons for the lack of difference in the Intention to Treat group is really best appreciated by looking at the difference in intervention rates in Table 2. Both treatment teams (additional physician or paramedic only) could intubate cold so we only report the rate of drug assisted intubation. This was by far the most common physician only intervention, and the one we have been suspecting to make the most difference to head injured patients. When you look at the rates receiving this intervention it was 10-14% in the paramedic only group due to the local ambulance service sending their own physician teams in a good percentage of patients, compared with 49-58% in the treatment group. If this really is the intervention that is going to make the difference, our chances of demonstrating that difference are not great unless the treatment effect is absolutely massive.

When the system you study changes

The Ambulance Service in NSW decided two and half years into the trial that they considered physician treatment to already have sufficient evidence to make it the standard of care. They partially replicated the trial case identification system to enhance identification of patients that they believed would benefit from dispatch of a physician (there’s more detail in the HIRT protocol paper).

This is not the first time that such a thing has happened. In the OPALS study of prehospital advanced life support in Canada in 2004 the original study design was a randomised trial (Callaham). It was however done as a cohort study owing to the belief of paramedics that it was unethical to withhold ALS despite absence of proof of its efficacy. We bemoan the lack of evidence but belief in the efficacy of established models of care make gathering high quality evidence impossible in many EMS systems. NSW has proved to be no exception.

Sydney remains a good place to do this work of course.

Where are we then?

So where does this leave Sydney? I think a quote from Prof Belinda Gabbe best sums up the situation. Prof Gabbe is a trauma researcher from Monash who has published much on the Victorian trauma system and was brought in as an external expert to review the HIRT outcome data during a recent review of the EMS helicopter system in New South Wales. Her comment was:

“As shown by the HIRT study, physician staffed retrieval teams are now an established component of standard care in the Sydney prehospital system. The opportunity to answer the key hypothesis posed by the study in this setting has therefore been lost and recommendation of another trial is not justified. Future trials of HIRT type schemes will therefore need to focus on other settings such as other Australian jurisdictions, where physician staffed retrieval teams are currently not a component of standard care”.

The only jurisdiction in Australia with enough patients to make such a study viable that does not already use physicians routinely is Victoria. Such a study would be particularly interesting as the recent randomised trial of paramedic RSI from that state found absolutely no difference in mortality, the area where the HIRT trial indicates there well may be a difference. Any potential trial funder would want some certainty that history would not repeat itself in the standard care arm however.

In NSW though, the question of whether physician care makes a difference to patient outcome is now a moot point. It is now the standard of care – HIRT has definitively demonstrated this if nothing else. All we can do now is determine the best way of providing that care. We have more to publish from the data set that provides significant insights into this question so watch this space.

References:

The Bind About Pelvic Binders – Part 4

February 27, 2015 careflightcollective 6 Comments

Is this the last bit for now? Dr Alan Garner following up on pelvic binders after all the stimulating comments. If you haven’t already, check out part 1, part 2 and part 3.

During the writing of part three of this series on pelvic fractures and particularly after reading Julian Cooper’s comments (thank you Julian) I realised that the observational data around pelvic binders does not entirely fit with the theories. Let’s start with the theory and I might directly borrow Julian’s comments from Part 2 as he says it better than I could:

“In any type of pelvic injury. the bleeding will be either:

Venous or bone ends: in which case keeping things still with a binder is likely to allow clot formation (low pressure bleeding, low or high flow).
“Slow” arterial (the sort of thing seen as a blush on contrast CT) which will probably trickle on even with a binder but at a rate which is compatible with survival to hospital and (ideally) interventional radiology if they don’t stabilise spontaneously (high pressure, low flow bleeding).
“Fast” arterial (e.g. free iliac rupture) which is likely to be fatal whatever one does, binder or not (high pressure, high flow bleeding).”

I need to state right up front that I agree with all of this. It all seems entirely reasonable and there is some cadaver evidence that movement of fractures associated with patient movement (e.g. sliding a patient from stretcher to a bed) is reduced when a binder is applied. It seems reasonable that a binder might slow, or at least reduce aggravation of venous and bone end bleeding with movement. It might even help the “slow” arterial bleeders too.

So what is my issue with all this? Studies like the Tan paper (15 patients) describe a dramatic and immediate increase in blood pressure associated with applying a binder to an “open book” style fracture and reducing it. Mean arterial pressure increased from 65mmHg to 81 and HR fell from 107 to 94 per min 2 minutes after application. The effect was associated with (although of course not necessarily caused by) reduction of the fracture. Nunn’s series of 7 patients showed even more dramatic changes in blood pressure measured at 15 minutes post binder application although they do not report the degree of fracture reduction achieved. Again we are dealing with tiny numbers of patients but the effect seems consistent – in shocked patients with anteroposterior compression or mixed type injuries who have a binder applied the blood pressure usually immediately rises (note one patient in Tan series who significantly deteriorated). In Nunn’s series with BP reported at 15 mins post application it is possible that the pelvis was “stabilised” and then a big fluid bolus was given but this cannot be the case in the Tan series where the effect is seen immediately.

Stabilising the pelvis against further movement and stopping venous and bone end bleeding cannot be the mechanism for this sudden rise in BP. Even stopping the “slow” arterial bleeders could not create such an immediate effect.

So what is going on? Warning – brainstorming not supported by any evidence following:

Compression of arteries in the pelvis resulting in increased systemic vascular resistance? (warned you about the brain storming – this seems pretty unlikely to me)
Compression of distended venous spaces causing a fluid shift back into the central circulation and increased BP. If this is the case then what you are seeing is a MAST suit effect and this has been shown to not necessarily be a good thing if you don’t also stop the bleeding.
One of my colleagues suggested it is pain associated with binder application that is causing the BP rise? Again doubt this is the case. Also not sure this is helpful if you are not also stopping the bleeding (as per MAST suit issues)

I don’t actually have a good theory for what is going on here but the effect is very clearly described in the literature. It seems to be a good thing although the Nunn paper in particular notes that ongoing volume resuscitation and other measures to stop the bleeding are usually then required. If anyone has any theories on what is happening here then please share with the rest of us.

A Recap

I might summarise the literature on pelvic binders as:

No study has yet demonstrated a significant decrease in mortality associated with binders
Increased fragment displacement, haemodynamic deterioration and some really ugly pressure injures (have a look at the case report by Mason for an absolute shocker) have been described with their use i.e. they are not benign.
They might decrease venous and bone end bleeding by preventing movement but we currently have no direct evidence to support this. Agree that this seems reasonable though.
An improvement in haemodynamics is often seen immediately at the time of application of a binder in shocked patients with an open pubic symphysis. Mechanism for this is currently unknown and we don’t have enough evidence to know whether this is actually a good thing or not. Going right back to part 1 of this series we should be very cautious about using surrogates such as improved BP as measures of outcome or binders may turn out to be MAST suit Mark 2.

I don’t want to be a wet blanket but I do believe that this is a realistic evaluation of the current evidence.

The Bottom Line on What I Do

Do I personally use binders prehospital?

Yes I do unless the injury is clearly lateral compression. I also am not afraid to loosen it again if the patient deteriorates. I think they are helpful for the open symphysis patients based on the documented haemodynamic improvement often seen in these patients but I acknowledge that I am hoping that this BP rise translates into lower mortality but I don’t have evidence to support this. I definitely will never criticise someone who has not put one on as there is just not enough evidence one way or the other.

Time for a segue – and perhaps a paradigm shift.

Come this way for other new thoughts but no more bad visual puns, people of the future. [Via Alan Kotok on flickr under CC 2.0]

The Ones Who Need More

Let’s look at Julian’s group 3: – ”Fast” arterial (e.g. free iliac rupture) which is likely to be fatal whatever one does, binder or not (high pressure, high flow bleeding). Again I agree with Julian here. These patients can die in minutes as is usually the case if you lacerate a vessel the size of the iliac artery, and there is absolutely nothing you can do about it prehospital.

Or is there?

Another thing I was taught as a boy is that if you can’t control arterial bleeding at the haemorrhage site then get proximal control. So how can you get proximal control for a punctured iliac artery? Clearly we are talking about occluding the aorta here but how do you achieve this prehospital?

The idea of REBOA (resuscitative endovascular balloon occlusion of the aorta) in the prehospital context has been getting a bit of attention with London HEMS recently introducing it. Now this sounds really sexy but it requires a skilled doctor with an ultrasound machine, time and good access to the patient. What I am proposing is the much simpler version of REBOA where the E stands for “External”.

Conflict of interest statement: Neither I nor either of my employers have a financial interest in the manufacture or distribution of the device I am about to mention – I just think it is a really cool idea.

The device is the Abdominal Aortic and Junctional Tourniquet (AAJT) (here’s the link to the manufacturer’s website for their obviously positive coverage). A reasoned discussion on the relative merits of AAJT over traditional endovascular REBOA and some of the literature on both approaches can be found here.

The nice thing is that it sits around the waist and does not limit access to groins so that endovascular REBOA remains an option when you hit the trauma centre. If you can get one of these things on fast enough then even free rupture of an iliac vessel will potentially be controllable.

There are no reports yet of this device being used in catastrophic pelvic fracture haemorrhage but there are lots of reports of manual compression of the aorta being used in other causes of massive pelvic haemorrhage such as penetrating trauma, post partum haemorrhage and pelvic surgery. There are reports of the device being successfully used for massive bilateral lower limb injury in the military context. It should work in pelvic fracture too if proximal control is the key (famous last words).

The AAJT seems like the ideal prehospital device as you can place it in about 45 secs, in some situations you may be able to place it in a patient who is still trapped or whilst in transit to the hospital. That is just not going to happen with endovascular REBOA. And of course you don’t need a highly skilled physician with an ultrasound machine. Might have lower sex appeal factor but if occluding the aorta saves lives, this device is going to save far more lives than endovascular REBOA as it can be applied by a lot more people in a wider variety of situations. It is possible to put on an AAJT as well as a Pelvic binder as the binder sits around the greater trochanters and the AAJT is positioned over the umbilicus.

My own service has now acquired some AAJTs and we are about to introduce them to service. We will try and update you on our experience as it is early days yet for this device.

Lastly apologies to Julian if I have in any way misrepresented his opinions or taken his comments out of context. His comments certainly got me thinking however and that is what the Collective is supposed to be about so thanks Julian for contributing.

References:

Mason LW, Boyce DE, Pallister I. Catastrophic myonecrosis following circumferential pelvic binding after massive crush injury: A case report doi:10.1016/j.injury.2009.01.101

Education

Why? How? What? Big Questions for Prehospital Simulation

January 29, 2015 careflightcollective 6 Comments

At CareFlight another round of training many people is about to come up so it seemed like a good chance to ask Dr Sam Bendall for her first contribution.

Sam is an Emergency Physician who is passionate about education, particularly all things simulation. She works half-time at Royal Prince Alfred Hospital in Sydney in the Emergency Department where she helped develop and teaches the RPA Trauma Team Training program, teaches on the CIN nurses programs and helped develop the ED Essentials program.

At CareFlight she is a retrieval doc (the other half-time) and the Deputy Director of Education. The CareFlight Education Team are always up to interesting things – from training the Australian Defence Force medical on how to look after all things ballistic, medical, surgical and paediatric, to running the Pre-Hospital Trauma Course both in Sydney and other locations (Malaysia, anyone?), to running Trauma Care Workshops all over the country. Oh, and of course all those working with CareFlight too.

Anyway, here’s Sam …

As a passionate advocate for simulation I look around and see this amazing tool appear in many guises, all under the same blanket term. It certainly seems to mean many things to many people depending on their previous experiences. In some ways it is the SWISS ARMY KNIFE of kinesthetic education. The coolest knife has pliers and scissors. However, just like a Swiss army knife, it can be a harmful weapon (hence the name!), just plain useless (like when you want the one with pliers but you only have the single blade), or a bit uninspiring and encourage automatic behaviours – e.g. all Swiss army knives are red and you should have one.

This clearly rubbish version doesn't even have the magnifying glass. — This clearly rubbish version doesn’t even have the magnifying glass.

Simulation has almost become the learning apparatus du jour – everyone has to do it but some are not sure why or how to really make it work. A bit like having a Swiss army knife so you can be part of the Swiss army, but it lives in the drawer.

I will put a disclaimer in at this point. The following are my own opinions – the musings of a dedicated simulation-phile after several years of training in simulation and doing simulation exercises for anywhere from 2 – 150 people.

So what’s the point?

I’m going to put a slightly different spin on it, with an emphasis on simulation for the pre-hospital environment. Simon Sinek, in his TED talk in 2009 titled “Start with Why” made a very powerful case for asking yourself WHY you want to do something… in this case, simulation, at the outset. The HOW and the WHAT will follow if you drill down onto the why and firmly establish WHY you want your participants to do simulation.

Simulation is a journey, for both the instructors and participants. Hopefully a journey towards some constructive learning, but one that will have many interesting twists and turns along the way. Being sure of WHY you are undertaking this part of the journey, gives you the freedom to explore the twists and turns of the journey without losing sight of the original intent. So my step 1 in building a simulation, is to ask yourself why? WHY are you doing this?

In our organisation, our WHY? is to create a mission-ready workforce.

Pre-hospital medicine throws out so many variables – communication, teamwork, environmental, situational awareness, medical challenges, geographical challenges and the list goes on.

In order to make our workforce mission ready, we need them to be critical thinkers, able to choose the right skill, equipment and approach for the right case at the right time.

Though if we had one of those shapeshifting Terminator ones could we program it to be friendlier?

We also need them to be aware of the variables they will need to deal with on real jobs so that they can manage them consciously. In order to do this we need to replicate as many of these variables as possible so they can address them in a training environment. We aim to send our participants out on jobs that feel just like the scenarios they have done in training. No pressure!

HOW? – choose your weapon…

The simulation menu is fairly extensive and limited only by your creativity and ability to structure it in a way that is true to the learning objectives and easy to follow for your participants. The key elements of creating a scenario, whether it be for 2 or 50 participants, is that they need to know the rules, boundaries, and premises for the scenario….. hmm sounds like parenthood!

So first decide on your structure. Is it an audience that is learning a concept for the first time and you need to do it for real, but slow it down? Well “pause and discuss” is your man. Do you need to see where your participants’ critical decision making is at and where the deficits lie? Immersive, relatively high fidelity simulation, with key variables built in, is the tool of choice.

Do you need to occupy 30 participants in a large scale simulation? – Create foci so the participants will need to form their own teams within the simulation. This will bring out all of the teamwork, communication and leadership points from the start.

Whatever weapon you choose, it needs to be appropriate to the audience, their experience and what you are trying to teach by doing the simulation exercise.

WHAT …the final frontier

Well this depends on what you are trying to deliver in your simulation. If, for example, your aim is to test and consolidate a new protocol, then the scale of your simulation can be quite limited. You may not need to bring in as many variables, or much fidelity. As long as the key prompts are there for the participants and they have the knowledge, skills and equipment to fulfill the protocol, then a limited scenario is fine.

BUT…. and there is a BIG but in this one. Be realistic in developing your scenario. If you are testing an ALS protocol, doing a bog standard ALS protocol with a patient in a bed may tick your box. BUT ….. in 20 years of medicine I think I have been to less than 10 arrests in ward beds and way more than 30 in other places – the toilet, the CT scanner, theatre, the foyer of the hospital, the waiting room, the beach etc. etc. You get the picture. So I would argue here that a bog standard ALS type scripted scenario has its place, but should be followed up by the application of the protocol where it is likely to happen and bring in the teamwork and communication aspects that we know actually make ALS protocols work in real life.

At CareFlight we educate using a “crawl, walk, run” paradigm.

First you crawl – i.e. you learn the skill or concept in isolation.
Then you walk – using relatively low fidelity simulation with limited learning outcomes, you learn to apply that skill appropriately.
Then you RUN. In our “RUN” scenarios, we introduce many more variables that replicate the environment they will have to operate in. We increase the fidelity and prompt the participants to evaluate the situation, decide whether that skill or concept is appropriate, apply it if it is or find an alternative if it is not. This layering approach helps to consolidate skills and knowledge and develops critical decision-making processes in a way that is directly applicable to the job we do.

When you get to the RUN scenario you are trying to bring out multiple learning points across many categories, for example:

Teamwork and communication (CRM)
Leadership skills (CRM)
Graded assertiveness and conflict resolution (CRM)
Scene safety and situational awareness (CRM, environmental and logistics)
Management of a multitrauma patient in an isolated environment (medical)
Packaging and preparation for transport (logistics, medical)
How to carry a patient out of the bush safely (logistics, medical)
Planning for contingencies e.g. weather etc. (logistics)

Then the scenario has to be much higher fidelity and be crafted in a way that replicates those key learning objectives – CRM, medical, environmental and logistic. You need to recreate the key environmental elements that will impact on the participants’ decision-making, bring in the key teamwork elements, replicate the equipment or types of equipment they will use and think about the team structures they will be given. Even simple tweaks to the scenario such as limiting access to the patient’s head, can improve the problem solving and CRM elements of the scenario so the devil is very much in the detail here. AND SO IS THE FUN …

Why yes that is a mobile rollover simulator that some clever people built ... — Why yes that is a mobile rollover simulator that some clever people built …

Prehospital Trauma

The Bind When it Comes to Using a Binder

August 2, 2014 careflightcollective 6 Comments

This post by Dr Alan Garner is the first of a trio on the topic of pelvic fractures and the evidence for what to do. Alan is an emergency physician at Nepean Hospital in Sydney and the Medical Director of CareFlight, having started in prehospital medicine in 1996. He has a bunch of other interests but there’s not enough space for that here.

Unfortunately I am old enough to remember when MAST suits were considered standard of care. In many states of the US it was law that ambulances had to carry them – that is how convinced everyone was that the things were doing good, not evil. We were all misled by measuring surrogates of outcome such as blood pressure rather than the outcomes that really matter, morbidity and mortality. Of course when good studies evaluating mortality were eventually done we discovered the evil side of the device and they are now almost a historical curiosity. In the context of this discussion it is rather ironic given that patients with open book pelvic fractures may have been the one group who might have benefited, at least from the upper portion of a MAST suit but that subgroup was never studied.

The question around MAST suits is how did they become a standard of care without good outcome data? And of course we are not silly enough to repeat the same mistake – are we?

New MAST Suit Fashion?

Moving on to the question of pelvic binders, many prehospital services now use them on all patients with a suggestive mechanism regardless of clinical or physiological signs of pelvic fracture and the practice is becoming more widespread. Is there evidence to support this? Are we even sure that we are doing more good than evil?

After all, what could possibly go wrong?

At first it seemed like a good idea ... — At first it seemed like a good idea …

Truth: there are no studies that show a significant improvement in mortality with use of pelvic binders. Ever. There are not even any cohort studies let alone randomised trials.

Given the dogma that is growing up around the use of the devices the above statement may come as a surprise. The best data on the physiological effects of binders comes from an observational study published in 2010 with just 15 patients and endpoints of MAP and HR two minutes post application in the hospital context (Tan). This is a long way from measuring the outcome that matters!

There is one other study indicating decreased transfusion requirements and length of hospital stay with in-hospital use of pelvic binders compared with external fixation (Croce). This study was a single centre retrospective study over a 10 year period with binders used in the later half when it is possible there other system changes such as more aggressive correction of coagulopathy. There was a trend towards lower mortality with the binders which was not significant, but these historical control studies over such long time periods should be treated with the caution they deserve. Bottom line is no significant change in the outcome that matters; mortality.

And this is the in-hospital data. There is no data on any type of outcome for prehospital application of binders.

You can see why I am a little scared about the path this is taking. Is there a potential for evil that we are ignoring here while we repeat the mistakes of the past?

A Quick Review

First the bits I think no one is disputing. Haemodynamically unstable pelvic fractures are a talk-and-die situation. Patients require rapid and aggressive treatment in order to survive.

Prevalence of pelvic fractures with severe blunt multiple trauma is between 5 – 11.9% and is associated with:

High energy forces (MVA, pedestrian v car, falls from heights)
Major haemorrhage, which can be difficult to control
Other major injuries
- Intra abdominal (28%)
- Hollow viscus injury (13%)
- Rectal injury (5%)

Mortality is high:

Mortality 10-30%;
Up to 50% if shocked;
70% with unstable open book fractures.

The cause of death is haemorrhage which has four potential sources of haemorrhage:

Surfaces of fractured bones
Pelvic venous plexus (90%)
Pelvic arterial injury (about 10%)
Extra pelvic sources

Suzuki et al (2008)

“Haemorrhage from a pelvic fracture is essentially bleeding into a free space, potentially capable of accommodating the patient’s entire blood volume without gaining sufficient pressure-depending tamponade”

True pelvic volume is about 1.5 litres, and is increased with disruption of the pelvic ring as the tamponade effect of the pelvic ring is lost with severe pelvic fractures. The retroperitoneal space, even when intact can accumulate 5 litres of fluid with only a pressure rise of 30mmHg so bleeding in this space will essentially never tamponade.

In other words this is like uncontrolled haemorrhage into the abdomen or chest; the patient will exsanguinate before it tamponades itself. For those of us out in the prehospital world, we can’t do anything about stopping abdominal and thoracic haemorrhage apart from perhaps tranexamic acid and move fast. Perhaps this is why so many services have embraced the pelvic binder believing that here at last is one form of internal haemorrhage in which we will be less impotent.

Stopping the bleeding has to be a good thing and there is some evidence that binders might decrease bleeding in certain fracture types. In the end all treatment is a balance of risk and pelvic binders are no different. To get the balance right though we need to know what the potential risks of an as yet unproven treatment actually are.

In part 2 of this discussion we will have a look at pelvic fracture pathology and classification so we can understand why binders might help but also “what could possibly go wrong” too.

(Ed: such a tease …)

References:

Croce MA, Magnotti LJ, Savage SA, Wood 2nd GW, Fabian TC. Emergent pelvic fixation in patients with exsanguinating pelvic fractures. Journal of the American College of Surgeons 2007;204:935–9. [discussion 40–2]

Tan ECTH, et al. Effect of a new pelvic stabilizer (T-POD1) on reduction of pelvic volume and haemodynamic stability in unstable pelvic fractures. Injury (2010), doi:10.1016/j.injury.2010.03.013

The Collective

Tag Archives: prehospital

HIRT – Studying a Non-Standard System that Ended up as Standard

The Bind About Pelvic Binders – Part 4

Why? How? What? Big Questions for Prehospital Simulation

The Bind When it Comes to Using a Binder

A Hive Mind for Prehospital and Retrieval Med