Tranexamic Acid - Update
Tranexamic Acid, (TXA) is an anti-haemorrhagic that helps to control severe bleeding. It was developed in Japan in the 1950s and initially used to control heavy menstrual bleeding and bleeding from tooth extractions.
Since the CRASH3 Trial, there have been a number of updates to its use in the prehospital environment for trauma and as they make a big difference to how and when it can be administered, we thought it would be useful to explain the changes. This podcast from PHEMCAST is a useful summary of the updates: PHEMCAST Podcast - TXA Update and this blog ocuses on the prehospital trauma indications for TXA.
TXA is an ‘anti-fibrinolytic’ which works by reducing the breakdown of any clots that form. Normally this process of breaking down a blood clot helps to protect the body, but if we’re bleeding out already, it could be fatal. The first clot is the strongest, and TXA works to keep that clot in place, stopping further blood loss.
TXA (as per MSN1905) is available to us in two presentations:
A 500mg tablet for medical use for longer-term management of bleeding - such as controlling heavy periods, or recurring nosebleeds.
A 500mg/5ml injection for trauma use - for severe internal or external haemorrhage such as a traumatic injury or obstetric/gynaecological bleeding.
In addition to its use prehospital for trauma, TXA can also be used following head injuries (GCS of 12 or less, without active extracranial bleeding) and postpartum haemorrhage.
TXA can also be used for local fibrinolysis, menorrhagia, hereditary angioedema, epistaxis, and general fibrinolysis.
One important note is that there are differences in the initial dose for trauma, depending on which country you were trained in. The US currently recommends an initial dose of 2g for trauma, the UK recommends 1g with a follow up 1g infusion in hospitals. So don’t worry if there is a difference of opinion, as both are correct and neither will do any harm as long as it’s administered within 3 hours.
Timing is another key consideration. TXA is most effective and must be administered in the first 3 hours - the earlier the better, as efficacy declines every 15 minutes. But it’s a contraindication if the bleeding started over 3 hours ago.
Indications
TXA can be administered to patients with signs of actual or suspected severe haemorrhage in the following clinical scenarios:
Trauma: Patients with a TIME CRITICAL injury where significant internal or external haemorrhage is known or suspected.
Treatment of known or suspected severe traumatic internal or external haemorrhage as soon as clinically possible on arrival at the scene and within 3 hours of bleeding starting in adults and children who are considered to be at risk of significant haemorrhage. This may be demonstrated by one or more of:
Systolic blood pressure < 90mmHg or absent radial pulse or heart rate > 110 bpm believed to be due to bleeding in adults. In children this may be demonstrated by changes in the normal physiological parameters for age.
Any patient where haemostatic gauze, arterial tourniquet/s, chest dressing/s or pressure dressing/s have been applied.
Patient who has suffered a traumatic cardiac arrest. The administration of tranexamic acid should not take precedence over, or interfere with, essential resuscitation tasks.
Head Injury: Patients who have a known or suspected head injury where the following criteria are met:
The GCS is 12 or less.
The injury has occurred within the last 3 hours.
It can also be given in a number of instances for Obstetric and Gynaecological bleeding including excessive bleeding after a confirmed miscarriage or termination of pregnancy, for PPH and gynaecological causes of vaginal bleeding. We might not expect to see this onboard, but it’s useful to know that it might be an option.
One area where results have not shown a major benefit is for upper gastrointestinal bleeds. It’s thought that this is because identification is normally over 3 hours after the start of an upper GI bleed.
So what’s new?
The recent trials have taken place across 40 countries with tens of thousands of patients taking part - which makes the results extremely significant.
What it’s shown is that we should give TXA based on the mechanism of injury. We don’t need to wait until there are clinical signs of shock and bleeding out. In addition to external bleeding that we can see, if the mechanism makes us suspect that the patient is likely to be bleeding internally, we can look beyond the obvious and administer it - it won’t do any harm.
The evidence categorically shows that the sooner we give TXA, the better. Every 15 minutes delay post injury reduces the effect, and if it’s given 3 hours or more after the injury, there is no negligible benefit. The great thing is that it will reduce the chance of death by a third, regardless of whether the trauma is major, such as an amputated limb, or a lower mechanism such as a fall from standing for a frail person. For those working onboard, it means considering the mechanism and putting in a telemedicine call sooner rather than later so that TXA can be given if appropriate.
We can now give TXA for known or suspected head injury in the last 3 hours, where the GCS is 12 or less.
Possibly THE most important change is that we can now give TXA via intramuscular (IM) injection. Previously it had to be given very slowly, over 10 minutes due to the risk of hypotension, by IV or IO. Now, it can be given IM into the arm or the leg, just give half in each side to spread the volume comfortably. Amazingly it works just as quickly as IV administration. This has major implications as it opens up the possibility of auto injectors being used at scene by non healthcare professionals in the future.
One interesting point from the research is that women are 50% less likely to be given TXA for a traumatic injury. There’s no apparent reason why, but we do know that women are also 27% less likely to receive CPR in the case of a cardiac arrest. So let’s do what we can to shake up those statistics and aim for a little health equality!
We hope you’ve found this blog useful and picked up a few pointers. Please let us know if there are any topics you would like to see in the future.
References and Resources:
Resources:
MSN 1905 - 4th Amendment (current version at time of writing)
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