Clinical utility of viscoelastic testing in chronic liver disease: A systematic review.
BACKGROUND
Conventional coagulation tests are widely used in chronic liver disease to assess haemostasis and to guide blood product transfusion. This is despite the fact that conventional tests do not reliably separate those with a clinically significant coagulopathy from those who do not. Viscoelastic testing such as thromboelastography (TEG) correlate with bleeding risk and are more accurate in identifying those who will benefit from blood product transfusion. Despite this, viscoelastic tests have not been widely used in patients with chronic liver disease outside the transplant setting.


AIM
To assess the utility of Viscoelastic Testing guided transfusion in chronic liver disease patients presenting with bleeding or who require an invasive procedure.


METHODS
PubMed and Google Scholar searches were performed using the key words "thromboelastography", "TEG" or "viscoelastic" and "liver transplantation", "cirrhosis" or "liver disease" and "transfusion", "haemostasis", "blood management" or "haemorrhage". A full text review was undertaken and data was extracted from randomised control trials that evaluated the outcomes of viscoelastic test guided transfusion in those with liver disease. The study subjects, inclusion and exclusion criteria, methods, outcomes and length of follow up were examined. Data was extracted by two independent individuals using a standardized collection form. The risk of bias was assessed in the included studies.


RESULTS
A total of five randomised control trials included in the analysis examined the use of TEG guided blood product transfusion in cirrhosis prior to invasive procedures (n = 118), non-variceal haemorrhage (n = 96), variceal haemorrhage (n = 60) and liver transplantation (n = 28). TEG guided transfusion was effective in all five studies with a statistically significant reduction in overall blood product transfusion compared to standard of care. Four of the five studies reported a significant reduction in transfusion of fresh frozen plasma and platelets. Two studies showed a significant reduction in cryoprecipitate transfusion. No increased risk of bleeding was reported in the three trials where TEG was used perioperatively or prior to an invasive procedure. Two trials in the setting of cirrhotic variceal and non-variceal bleeding showed no difference in control of initial bleeding. In those with variceal bleeding, there was a statistically significant reduction in rate of re-bleeding at 42 d in the TEG arm 10% (vs 26.7% in the standard of care arm P = 0.012). Mortality data reported at various time points for all five trials from 6 wk up to 3 years was not statistically different between each arm. One trial in the setting of non-variceal bleeding demonstrated a significant reduction in adverse transfusion events in the TEG arm 30.6% (vs 74.5% in the control arm P < 0.01). In this study there was no significant difference in total hospital stay although length of stay in intensive care unit was reduced by an average of 2 d in the TEG arm (P = 0.012).


CONCLUSION
Viscoelastic testing has been shown to reduce blood product usage in chronic liver disease without compromising safety and may enable guidelines to be developed to ensure patients with liver disease are optimally managed.
['Wei|Henry|H|', 'Child|Lauren Jane|LJ|']
Viscoelastic testing Chronic liver disease Coagulation Haemostasis Thromboelastography Cirrhosis End stage liver disease Rotational thrombelastometry