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?
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 …)
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]