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Three Part Question

Should we be using [point of care testing, such as TEG machines], to guide [blood product replacement stratergies] for [trauma patients with massive bleeding]?

Clinical Scenario

Whilst on duty in the ED, a young man is brought into the resuscitation room with a stab wound to his abdomen. A trauma call is put out and resuscitative measures started. Primary survey includes a positive FAST scan. The bleeding is severe and the Trauma Lead initiates the massive transfusion protocol. Packed red cells, platelets and FFP are transfused in a 1:1:1 ratio, as per protocol. The patient is taken to theatre to control the bleeding. As he is leaving, the Trauma Lead asks you to take a further clotting sample to measure PT, APTT and INR so that 'we’ll know how many more products to give him’.
You follow up this patient and find that he survived and is currently on ITU. The Intensivist tells you he is suffering from ARDS, likely to be a Transfusion Associated Lung Injury (TRALI). The Intensivist believes the patient received far too many blood products during his resuscitation and in theatre. You wonder if there is a way of guiding blood product replacement in trauma situations which may supersede rigid transfusion protocols. You are aware that TEG machines are used to guide blood product replacement for open cardiac surgery patients and wonder if the same technique could be used to guide transfusion for trauma patients.

Search Strategy

Medline(1966-present) and Embase (1980-present) were searched via the NHS Evidence interface.
The words [exp trauma OR exp injury.ti,ab] AND [ exp coagulation OR coagulopathy OR transfusion.ti,ab], AND [thrombelastography, OR thromboelastometry.ti,ab] were searched. Search was limited to human studies and English language.

Search Outcome

34 unique results, of which 6 papers were suitable for this article.

Relevant Paper(s)

Author, date and country	Patient group	Study type (level of evidence)	Outcomes	Key results	Study Weaknesses
Plotkin et al February 2008 USA	n=44. Patients who suffered penetrating injuries presenting to a combat hospital.	Retrospective study.		TEG can be used to guide transfusion requirements/develop massive transfusion protocols.	Single centre. Retrospective study. TEG study performed 6 hours post admission, when patients had already received blood products.
				TEG was a more accurate indicator for blood product requirements than PT, PTT and INR.
Kashuk et al April 2010 USA		Review article.		TEG can optimize transfusion in critically injured patients at risk of coagulopathy.	Review only. No high quality research included.
				TEG offers opportunity for earlier correction of coagulation abnormalities with more efficient restoration of physiological homeostasis.
				TEG helps reduce transfusion volumes via specific goal directed treatment of identifiable coagulation abnormalities.
Kashuk et al 2009 USA	n=44 Severly injured patients admitted to a single trauma centre, during a six month period.	Retrospective study.		Conventional coagulation tests would have resulted in blood product administration to 73% of patients compared with 53% based on rTEG thresholds.	Single centre. Retrospective research.
Rugeri et al February 2007 France	n=90 Trauma patients admitted to one trauma centre over the course of 4 months.	Prospective observational study.		rTEG can detect early changes of in vivo coagulation in trauma patients.	Study made use of cut-off values for transfusion; these were different from those classically used in clinical practice. No effort made to eliminate confounding factors.
				Point of care devices may allow physicians to detect and treat early trauma coagulopathy and have the advantage of measuring all parts of the coagulation process.
Johansson et al September 2009 Denmark		Review article.		When evaluating trauma patients, characteristic [TEG] profiles are found to be related to Injury Severity Score (ISS) and mortality.	Review article. No high quality research included. Potential conflict of interest cited by the main author.
				Different TEG traces indicate that different transfusion strategies may be appropriate.
				TEG is more sensitive than PT/APTT in correlating coagulopathy with fatality.
Stahel et al April 2009 USA		Review article.		Transfusion strategies should be guided by TEG defined parameters.	Review article. No high quality research included.

Comment(s)

Haemorrhage accounts for ~50% of deaths in the first 24 hours of trauma care. Traumatic coagulopathy is a hypocoagulable state that occurs in the most severely injured. Most transfusion protocols are based on work performed by military physicians, based on the theory that coagulation factors need to be replaced in large quantities. The studies appear to confer a survival benefit when using these protocols. However, a degree of survival bias may play a role in the conclusions reached. Although there is a role for transfusion protocols, receiving higher levels of transfusion is known to increase morbidity and mortality in trauma patients. When comparing patients with an identical ISS, mortality doubles as a result of increased coagulopathy. It is known that increased FFP and platelet usage is strongly associated with higher levels of TRALI. TEG is a laboratory method which provides a rapid point of care test that qualitatively measures the entire coagulation cascade. TEG has been used to lower the levels of blood transfusion in open heart surgery. Given that the exact ratio of product replacement is currently a debated topic in haemostatic resuscitation, there appears to be a role for TEG to help guide product replacement in trauma. Best evidence thus far shows that TEG is more sensitive than current modalities for guiding transfusion and can detect coagulopathies at an earlier point during resuscitation. TEG has the potential to become a cornerstone for the development of future massive transfusion protocols.

Clinical Bottom Line

TEG can be used as a point of care test to guide transfusion in haemorrhagic trauma. Further well organised clinical trials are needed to assess if TEG can improve haemostatic resuscitation and help reduce transfusion associated mortality/morbidity.

References

1. Plotkin et al A reduction in clot formation rate and strength assessed by thromboelastography (TEG) is indicative of transfusion requirements with penetrating injuries. Journal of Trauma. February 2008 Vol 64(2) pp64-68 Supplement.
2. Kashuk et al Postinjury Coagulopathy Management. Goal Directed Resuscitation via POC Thromboelastography Annals of Surgery. pp 604-614 Volume 251, No 4 April 2010
3. Kashuk et al Non-citrated whole blood is optimal for evaluation of postinjury coagulopathy with point –of-care rapid thromboelastography (rTEG). Journal of Surgical Research. Vol 156, pp133-138. 2009.
4. Rugeri et al Diagnosis of early coagulation abnormalities in trauma patients by rotation thromboelastography (rTEG) Journal of Thrombosis & Haemostasis. Volume 5 Issue 2 pp 289-295. Feb 2007
5. Johansson et al Thromboelastography and thromboelastometry in assessing coagulopathy in trauma. Scandinavian Journal of Trauma, Resuscitation and Emergency Medicine. Volume 17:45 September 2009
6. Stahel et al Transfusion stratergies in postinjury coagulopathy. Current Opinion in Anaesthesiology Vol 22 pp289-298. April 2009