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The Bind About Pelvic Binders (Part 2)

This is part 2 in Dr Alan Garner’s series on pelvic fractures and the approach to binders. You can find part 1 here

In part one we had a look at the evidence for benefit from pelvic binders. In short there is no study yet published showing a significant improvement in mortality. Not even a cohort study.

Of course, it still might be OK to use them if they possibly help as long as there is no evidence of harm either (and they don’t cost too much). The probability of good has to outweigh the probability of evil. It is the potential for evil that I want to examine now so we can see where the balance lies.

Before we can do that though we need to have a quick look at the types of pelvic ring fractures (no one is suggesting that non-pelvic ring fractures of the pelvis benefit from a binder). So sorry folks but we have a bit of theory to re-visit.

Forces Down There

I use the Young and Burgess classification system as it is based on the force vector that caused the injury. In the prehospital world mechanism of injury is almost the only guide to injury type that is available to us (ultrasound may also give us some clues but we will talk about that in part 3).

AP compression injuries

AP Compression copy

This is an anteroposterior (AP) compression injury. This is the kind of fracture you see in frontal motor vehicle collisions, commonly in motor bike riders, and people who have been crushed by a vehicle rolling over their pelvis for example. The hallmark is pubic diastasis with or without disruption of the SI joints. The AP compression causes the pelvis to open: one or both hemipelves undergo external rotation.

External rotation of the hemipelvis results in an increase in the volume of the pelvic cavity which then allows more pelvic haemorrhage to occur before the osseous and soft-tissue structures cause tamponade. Exsanguination is the primary risk & reduction of the increased pelvic volume is one of the goals of prehospital care.

When I was a boy Master taught me the way to reduce a fracture is to reverse the force that caused it in the first place. With this type of injury a pelvic binder makes biomechanical sense because it reverses the direction of the force which caused it. In severe AP compression injuries one or both hemipelves have been rotated backward. Applying a binder will rotate the hemipelves back towards each other, or “close the book”.

Book copy

As I mentioned in part 1 there is very little evidence on whether this is actually helpful despite the theoretical benefit. Tan’s study was observational and involved only 15 subjects in an emergency department setting. All subjects had been X-rayed prior to application of the device so the type of injury was known (unlike our context in most cases). Nine of the 15 patients in this study had AP compression type injuries with wide diastasis of the pubic symphysis.   Although there is some missing data, all patients with this pattern either had no change in MAP or it improved. So far so good.

There is a similar English study with 3 severe AP compression injury patients who improved with a binder (Nunn) but numbers are obviously pretty small.

Croce’s study appears to have had mostly AP compression fracture types (186 patients with breakdown between types not stated). Decreased transfusion requirements were found in the binder group at 24 and 48 hours (significant), the patients had decreased length of stay (significant), and lower mortality (non-significant). This does provide some support for use in severe AP compression injuries noting the methodology issues which I discussed in Part 1 with a retrospective study that included patients over a 10 year period.

There are a number of other studies which show improved alignment +/- blood pressure rise in AP compression type fractures in trauma patients, in cadavers and even in one prehospital study. None of these studies assess patient outcome though (I acknowledge this is difficult in cadaver studies!) Reduction can be so good that the fracture is difficult to see on subsequent Xray.

So in AP compression injury all the evidence points to better anatomical alignment, higher blood pressure, lower transfusion requirements, and shorter length of hospital stay when you use a binder. Mortality might be better too, but this remains to be proven. The important thing is there are no reports of adverse events in this group. When you see this fracture type on Xray or the mechanism suggests this injury – go for the binder. The risk of adverse advents is certainly outweighed by the possible benefits based on the best current evidence.

Lateral compression injuries

Lateral compression copy

Lateral compression injury results in internal rotation of the affected hemipelvis. This internal rotation decreases rather than increases the pelvic volume so they tend to bleed less than the other types. Life threatening haemorrhage is still possible though. The hallmarks include sacral buckle fractures and horizontal pubic rami fractures.

Remember my boyhood teaching – “Grasshopper, to reduce fracture you must reverse force that caused it”. There is an obvious problem here as applying a binder replicates the causal force and if anything is likely to make it worse.

Have a look at this Xray of a lateral compression injury. Put a binder around the greater trochanters and pull. Are you a force for good or evil?

X-ray copy

So what is the evidence? The Tan paper did not include any lateral compression injuries – remember that they had looked at the X-ray prior to application. I assume they looked and thought “well that is not going to help”. There is no evidence the Croce study included any either.

Is there evidence that a lateral compression fracture can get worse with a binder? (You have to be suspicious when binder studies appear to have avoided this fracture type altogether).

A recent Australian study (Toth) from 2012 had 8 cases with lateral compression that had binders applied. In three it resulted in increased pelvic deformity on subsequent Xray. They did not report the haemodynamic consequences. In the other 5 there was no improvement. There is biomechanical evidence of this in cadavers too e.g. Bottlang et al (if you look at this paper note again that they did not even attempt it in the LC3 injuries – the most severe grade).

Now this really disturbs me. There are docs I have met who are adamant that pelvic fracture patients should not be logrolled & should only be moved on scoop stretchers etc because the fracture fragments might move just with this limited motion. These same docs are however happy to put a binder on regardless of mechanism and pull, creating a much larger force than a logroll does, when we have direct evidence that binders increase fragment displacement in lateral compression injuries. Some consistency would be nice.

The bottom line is that there is no theoretical reason to believe that binders help in lateral compression injuries and lots of reasons to think they might make things worse. There is direct evidence in real world trauma patients that increased deformity of the pelvis does occur. There is no published data at all on the haemodynamic consequences when this happens, but I am betting you are not going to see improvement. The balance of risk here is on the dark side, not the light.

Bottom line is leave the binder in the bag in the bag for clear lateral compression mechanisms. It cannot help and there is published evidence of harm.

 

(Stay tuned for part 3 where we’ll get to vertical shear injuries – and other stuff).

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

Nunn T, Cosker TDA, Bose D, Pallister I. Immediate application of improvised pelvic binder as first step in extended resuscitation from life-threatening hypovolaemic shock in conscious patients with unstable pelvic injuries. Injury, Int. J. Care Injured (2007) 38, 125—128.

Bottlang M, KriegJ C, Mohr M, Simpson TS, Madey SM. Emergent management of pelvic ring fractures with use of circumferential compression. J Bone Joint Surg Am 2002;84-A(Suppl 2):43–7.

Who gets to tell the story?

Medicine is a discipline built for the campfire. Or a theatre. Or for the gossip of the tearoom. We build knowledge and teams quicker with the stories we share than the papers we read.

This is particularly the case for prehospital and retrieval medicine. This is an area of medicine bordering different lands to hospital practice. Borderlands tend to be inhabited by strange beasts (and let’s be honest, a few strange people). Some of the situations we find ourselves in are unlikely to repeat themselves quickly and if we don’t hear the stories of those who have been there before, it’s a lot harder to be ready for some of those more colourful days at work. That’s partly what sites like this are about.

We also inhabit a time when sharing stories is easier than ever. Not only in the brilliant and stimulating FOAMed community either. Everyone wants to share their version of events.  Everyone in the media. Everyone with a  phone. This only makes it more vital to ask: who benefits from the stories we share?

Somewhere on a Road

This might be easier to think about using a case.  A prehospital medical service is called to a road traffic accident. There’s just the one car involved with a 35 year old male unconscious at the scene and thought to have chest injuries. On scene  there is a challenging extrication requiring assistance from the local firies. Before that though the decision is made to anaesthetise, intubate and mechanically ventilate while in the vehicle.  The patient is thought to have a head injury but also has free fluid in the abdomen on ultrasound and the subsequent packaging and resuscitation during transport is worthy of plenty of discussion.

This would not be an unusual case but there is plenty that would make you want to talk about it. That chat would be most useful if it included details of the accident, an assessment of the injuries at the time, what was done and what the outcomes were. We’d all like to hear it.

Of course it might not just be the medical crews who want to spread the word. The prehospital service may well have an interest in telling the world of the work their teams are doing. That might be part of showing off what they do, or to promote important health messages.

The media, desperate to fill any available empty space with something other than coverage of plasticised reality show contestants shedding their dignity to secure a future in C-grade dinner theatre restaurants, will be all over it.

Those running media coverage may not meet the definition of 'super genius' [via thechive.com]
Those running media coverage may not meet the definition of ‘supergenius’ [via thechive.com]
Then there’s the potential for modern digital rubbernecking. It isn’t at all unusual to see numerous phones out recording footage of prehospital teams in action. By the time the team restocks the pack, that job may already be a fresh online instalment of very literal car crash TV.

All of these groups have something they feel they gain from sharing the story. Except for the patient of course. What do they gain? Not much that I can see. Which is why it’s only getting more important to do what we can to protect our patients from their stories spreading too wide.

Protecting our Patients

So extra care is probably needed in safeguarding their privacy, at least for the information that is in our control (media and bystanders add an extra level of complexity).  The debrief after the job is one thing, but if you’re sharing cases for education or meeting purposes it seems like there’s a few obvious things to do:

1. Ask the patient

The best way to go about it is surely to seek permission from the patient wherever possible. The limits of what you can and can’t say will be clear and any discussion will be far better informed by knowing how the story developed for them.

2. Decide how much of the story is vital

This applies to any one of those players interested in telling the story. Plenty of good learning is still possible without every last detail.

3. Deidentify everything That should be obvious. There’s no need to retell identifying information but deidentification should extend further than that. For cases where you plan to present details in another forum or via other media, everything stored about that case should also be de-identified. I used to be more relaxed about what was stored electronically, but given alarming descriptions of the laxity of computer security from people who actually know stuff (like here), it’s safer to assume everything is always vulnerable.

4. Leave some things unsaid

Any time you share the story, even when from your perspective, you’re also sharing the patient’s story. So is the potential gain from the story, be it educational or any of the other potential benefits, enough to justify telling another’s story? There may be some cases where the potential risks of story details coming out make it much more important to suppress information.

What if that crash involves a kid? Would that change your approach to retelling the story, or letting the story get out to a wider audience?

What if the crash occurs because the car goes into a tree? The one tree on a long, straight stretch of road. Wouldn’t it be more important to protect the patient from their story potentially getting out into the community? Some stories should probably be left in place.

Perhaps I’m overthinking this. Maybe some would not see there being much risk when we share battle stories. But the more I think about the full range of responsibilities I have to the patient, the more I think I need to try and draw a line somewhere. The problem is the line keeps shifting on me.

This post came from Dr Andrew Weatherall who does prehospital medicine with CareFlight and kids anaesthesia most of the rest of the time. He also blogs over at http://www.theflyingphd.wordpress.com on stuff related to being a PhD student amongst other miscellany. 

The Bind When it Comes to Using a Binder

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