Point-of-care coagulation testing for postpartum haemorrhage

The use of viscoelastic haemostatic assays (VHAs) to guide blood product replacement during postpartum haemorrhage is expanding. Rotem and TEG devices can be used to detect and treat clinically significant hypofibrinogenaemia, although evidence to support the role of VHAs for guiding fresh frozen plasma and platelet transfusion is less clear. If Rotem/TEG traces are normal, clinicians should investigate for another cause of bleeding, and haemostatic support is not required. Guidelines support the use of VHAs during postpartum haemorrhage as part of locally agreed algorithms. There is a wide consensus that fibrinogen replacement is needed if the Fibtem A5 is <12 mm and if there is ongoing bleeding. Guidelines recommend against using VHAs to guide tranexamic acid infusion, and this drug should be given as soon as bleeding is recognised, irrespective of the Rotem/TEG traces. The cost-effectiveness of VHAs during postpartum haemorrhage needs to be addressed.

Dynamic use of fibrinogen under viscoelastic assessment results in reduced need for plasma and diminished overall transfusion requirements in severe trauma

BACKGROUND

Despite advances in trauma management, half of trauma deaths occur secondary to bleeding. Currently, hemostatic resuscitation strategies consist of empirical transfusion of blood products in a predefined fixed ratio (1:1:1) to both treat hemorrhagic shock and correct trauma-induced coagulopathy. At our hospital, the implementation of a resuscitation protocol guided by viscoelastic hemostatic assays (VHAs) with rotational thromboelastometry has resulted in a goal-directed approach. The objective of the study is twofold, first to analyze changes in transfusion practices overtime and second to identify the impact of these changes on coagulation parameters and clinical outcomes. We hypothesized that progressive VHA implementation results in a higher administration of fibrinogen concentrate (FC) and lower use of blood products transfusion, especially plasma.

METHODS

A total of 135 severe trauma patients (January 2008 to July 2019), all requiring and initial assessment for high risk of trauma-induced coagulopathy based on high-energy injury mechanism, severity of bleeding and hemodynamic instability were included. After 2011 when we first modified the transfusion protocol, a progressive change in transfusional management occurred over time. Three treatment groups were established, reflecting different stages in the evolution of our strategy: plasma (P, n = 28), plasma and FC (PF, n = 64) and only FC (F, n = 42).

RESULTS

There were no significant differences in baseline characteristics among groups. Progressive implementation of rotational thromboelastometry resulted in increased use of FC over time ( p < 0.001). Regression analysis showed that group F had a significant reduction in transfusion of packed red blood cells ( p = 0.005), plasma ( p < 0.001), and platelets ( p = 0.011). Regarding outcomes, F patients had less pneumonia ( p = 0.019) and multiorgan failure ( p < 0.001), without significant differences for other outcomes. Likewise, overall mortality was not significantly different. However, further analysis comparing specific mortality due only to massive hemorrhage in the F group versus all patients receiving plasma, it was significantly lower ( p = 0.037).

CONCLUSION

Implementing a VHA-based algorithm resulted in a plasma-free strategy with higher use of FC and a significant reduction of packed red blood cells transfused. In addition, we observed an improvement in outcomes without an increase in thrombotic complications.

LEVEL OF EVIDENCE

Therapeutic/Care Management; Level IV.

Rotation thromboelastometry velocity curve predicts blood loss during liver transplantation

BACKGROUND

Patients undergoing liver transplantation (LT) have a high risk of bleeding. The goal of this study was to assess whether the first derivative of the velocity waveform (V-curve) generated by whole blood rotation thromboelastometry (ROTEM^®) can predict blood loss during LT.

METHODS

Preoperative V-curve parameters were retrospectively evaluated in 198 patients. Patients were divided into quartiles based on blood loss: low (LBL) in the first quartile and high (HBL) in the higher quartiles. A subgroup analysis was performed with patients stratified according to cirrhosis aetiology. A logistic regression model and receiver operator characteristics (ROC) curve were used to test the capacity of the V-curve, to discriminate between LBL and HBL.

RESULTS

In the HBL group, the V-curve showed a lower maximum velocity of clot generation (MaxVel), a lower area under maximum velocity curve (AUC), and a higher time-to-maximum velocity (t-MaxVel) than in the LBL group. t-MaxVel was the only parameter showing a capacity to discriminate between the two groups, with a ROC area of 0.69 (95% CI; 0.62-0.74). The ROC area was 0.78 (95% CI; 0.75-0.83) for the 148 patients with cirrhosis, 0.73 (0.60-0.82) for patients with viral hepatitis and 0.83 (0.78-0.96) for patients with alcoholic hepatitis, the group that showed the best discriminative capacity. Moderate but significant correlations were found between all parameters of V-curve and BL.

CONCLUSIONS

Pre-transplant V-curve obtained from ROTEM is a promising tool for predicting BL risk during LT, particularly in patients with cirrhosis.