With respect to transfusion protocols for massive haemorrhage; discuss the advantages and disadvantages of using a protocol guided by thromboelastography (TEG guided) compared to one that uses a fixed ratio of product replacement (e.g. FFP : platelets : packed cells = 1 : 1 : 1).
Heterogeneous nature of the critically bleeding trauma patient and the spectrum of trauma induced coagulopathy may mean fixed ratio protocol (FRP) is too simplistic to apply to all patients. Although a FRP may improve survival, the optimal ratio of packed cells to other blood components is unknown. TEG-guided algorithms allow rapid identification and correction of patient-specific coagulation abnormalities. Trauma induced coagulopathy in the critically bleeding patient is complex and changes throughout time of resuscitation, therefore TEG allows repeated assessment and correction throughout resuscitation period.
TEG-guided MHP algorithms, as compared to FRP may limit unnecessary blood product transfusion and the associated complications (e.g. TRALI, volume overload) of giving high volumes of plasma and other products, while ensuring appropriate clotting factors are replaced as required (i.e. allows targeted intervention to replace coagulopathy with fewer side effects)
Advantages of TEG compared with FRP
Patient specific – therefore may limit unnecessary blood product transfusion and the associated complications (e.g. TRALI, transfusion reaction, volume overload, TACO, immunomodulation, allergy)
Patient specific – therefore ensures appropriate clotting factors are replaced when required (i.e. allows rapid targeted intervention to replace coagulopathy with fewer side effects)
Aids rapid identification of when there is an ongoing medical cause of bleeding (i.e. ongoing coagulopathy) versus purely surgical bleeding with the need to progress surgical intervention.
Detects fibrinolysis and hyperfibrinolysis which may be particularly relevant in the critically bleeding trauma patient.
TEGs have a higher sensitivity than standard laboratory tests to detect trauma induced coagulopathy and are faster than lab-based tests.
Even a 1:1:1 (plasma:platelets:packed cells) delivers dilute coagulation factors compared with whole blood; ideal ratio of blood products to packed cells in FRP remains debated.
Disadvantages of TEG compared with FRP
Machine (ROTEM or TEG) not available in all centres;
More expensive than standard laboratory coagulation testing
Ability to manage MHPs in multiple trauma patients simultaneously limited by number of machines available
Requires adequate volume of blood sample to run test and can’t be performed on intraosseous sample; therefore, may not be able to be performed on critically unwell patient with difficult iv access.
May delay lab preparation (thawing) of blood products while awaiting result; compared with fixed ratio protocol where products immediately thawed and delivered. (i.e. FRP allows rapid delivery of blood products independent of test results)
Requires interpretation of values to guide blood product use.
Not valid to assess effects of platelet function, direct thrombin inhibitors, LMWH, warfarin
Controversial; evidence exists to support TEG in identifying trauma induced coagulopathy, but limited RCT trials on role of TEG-guided MHP algorithms
STATA trial currently ongoing (FRP vs thromboelastometry guided MHP in trauma patients)
Single centre RCT reports reduced blood transfusion rates and improved-survival with TEG-guided MHP (Gonzalez 2016) (compared with MTP guided by conventional coagulation assays)
Systematic review (2014) – 55 observational studies on use of TEG to guide blood product use in trauma:
Note: The level of detail in the evidence section was not expected.
A very topical question that was generally answered in a very superficial way. Detailed reference to the weak evidence base was not required, but some recognition of this fact was expected. Better structure often ensured better marks.
The examiners referred to TEG specifically in the question and throughout the answer, but it is clear that they were using the term interchangeably with ROTEM, and so in the discussion to follow TEG is also used as a surrogate for all forms of global testing for clotting function. Though the question asked specifically for a discussion of advantages and disadvantages, the college answer was formulated in a "critically evaluate" fashion which typically calls for a description of the rationale and supporting evidence As such, some mutant combination of the two answer formats is offered here, as a compromise which satisfies the authors' unhealthy preoccupation with tabulated answers.
Rationale for TEG-guided massive transfusion
Advantages of TEG
Disadvantages of TEG
Advantages of fixed ratio massive transfusion
Disadvantages of fixed ratio massive transfusion
Evidence which compares TEG-guided protocols with fixed ratio transfusion
Sankarankutty, Ajith, et al. "TEG® and ROTEM® in trauma: similar test but different results." World J Emerg Surg 7.Suppl 1 (2012): S3.
Coakley, Margaret, et al. "Transfusion triggers in orthotopic liver transplantation: a comparison of the thromboelastometry analyzer, the thromboelastogram, and conventional coagulation tests." Journal of cardiothoracic and vascular anesthesia 20.4 (2006): 548-553.
Venema, Lieneke F., et al. "An assessment of clinical interchangeability of TEG® and ROTEM® thromboelastographic variables in cardiac surgical patients." Anesthesia & Analgesia 111.2 (2010): 339-344.
Nielsen, Vance G. "A comparison of the Thrombelastograph and the ROTEM." Blood Coagulation & Fibrinolysis 18.3 (2007): 247-252.
Wikkelsoe, A. J., et al. "Monitoring patients at risk of massive transfusion with Thrombelastography or Thromboelastometry: a systematic review." Acta Anaesthesiologica Scandinavica 55.10 (2011): 1174-1189.
Hunt, Harriet, et al. "Thromboelastography (TEG) and rotational thromboelastometry (ROTEM) for trauma‑induced coagulopathy in adult trauma patients with bleeding." Cochrane Database of Systematic Reviews 2 (2015).
Nielsen, Jorn Dalsgaard, and Galloway Gregg. "Monitoring novel anticoagulants dabigatran, rivaroxaban and apixaban by thrombelastography. Proof of concept." (2013): 4813-4813.
Wikkelsø, A., et al. "Thromboelastography (TEG) or rotational thromboelastometry (ROTEM) to monitor haemostatic treatment in bleeding patients: a systematic review with meta‐analysis and trial sequential analysis." Anaesthesia 72.4 (2017): 519-531.
Gonzalez, Eduardo, et al. "Goal-directed hemostatic resuscitation of trauma-induced coagulopathy: a pragmatic randomized clinical trial comparing a viscoelastic assay to conventional coagulation assays." Annals of surgery 263.6 (2016): 1051.
Da Luz, Luis Teodoro, et al. "Effect of thromboelastography (TEG®) and rotational thromboelastometry (ROTEM®) on diagnosis of coagulopathy, transfusion guidance and mortality in trauma: descriptive systematic review." Critical Care 18.5 (2014): 518.