Viscoelastic haemostatic assays and fibrinogen in paediatric acute traumatic coagulopathy: A comprehensive review

The Role of Viscoelastic Testing in Assessing Hemostasis: A Challenge to Standard Laboratory Assays?

Viscoelastic testing is increasingly being used in clinical and research settings to assess hemostasis. Indeed, there are potential situations in which viscoelastic testing is reportedly superior to standard routine laboratory testing for hemostasis. We report the current testing platforms and terminology, as well as providing a concise narrative review of the published evidence to guide its use in various clinical settings. Notably, there is increasing evidence of the potential utility of viscoelastic testing for assessment of direct oral anticoagulants, and bleeding associated with chronic liver disease, orthotopic liver transplantation, cardiac surgery, trauma, obstetrics and pediatrics.

Hypofibrinogenemia following injury in 186 children and adolescents: identification of the phenotype, current outcomes, and potential for intervention

Objectives

Recent studies evaluating fibrinogen replacement in trauma, along with newly available fibrinogen-based products, has led to an increase in debate on where products such as cryoprecipitate belong in our resuscitation strategies. We set out to define the phenotype and outcomes of those with hypofibrinogenemia and evaluate whether fibrinogen replacement should have a role in the initial administration of massive transfusion.

Methods

All patients <18 years of age presenting to our trauma center 11/17-4/21 were reviewed. We then evaluated all patients who received emergency-release and massive transfusion protocol (MTP) products. Patients were defined as hypofibrinogenemic (HYPOFIB) if admission fibrinogen <150 or rapid thrombelastography (r-TEG) angle <60 degrees. Our analysis sought to define risk factors for presenting with HYPOFIB, the impact on outcomes, and whether early replacement improved mortality.

Results

4169 patients were entered into the trauma registry, with 926 level 1 trauma activations, of which 186 patients received emergency-release blood products during this time; 1%, 3%, and 10% were HYPOFIB, respectively. Of the 186 patients of interest, 18 were HYPOFIB and 168 were non-HYPOFIB. The HYPOFIB patients were significantly younger, had lower field and arrival Glasgow Coma Scale, had higher head Abbreviated Injury Scale, arrived with worse global coagulopathy, and died from brain injury. Non-HYPOFIB patients were more likely to have (+)focused assessment for the sonography of trauma on arrival, sustained severe abdominal injuries, and die from hemorrhage. 12% of patients who received early cryoprecipitate (0-2 hours) had higher mortality by univariate analysis (55% vs 31%, p=0.045), but no difference on multivariate analysis (OR 0.36, 95% CI 0.07 to 1.81, p=0.221). Those receiving early cryoprecipitate who survived after pediatric intensive care unit (PICU) admission had lower PICU fibrinogen and r-TEG alpha-angle values.

Conclusion

In pediatric trauma, patients with hypofibrinogenemia on admission are most likely younger and to have sustained severe brain injury, with an associated mortality of over 80%. Given the absence of bleeding-related deaths in HYPOFIB patients, this study does not provide evidence for the empiric use of cryoprecipitate in the initial administration of a massive transfusion protocol.

Level of Evidence

Level III - Therapeutic/Care Management.

Rotational thromboelastometry in children presenting to an Australian major trauma centre: A retrospective cohort study

Objective

This retrospective cohort study aims to describe patterns of rotational thromboelastometry (ROTEM™) results in paediatric trauma following the implementation of a ROTEM‐guided critical bleeding algorithm and major haemorrhage protocol (MHP).

Methods

This retrospective observational study was conducted in a tertiary trauma hospital in Queensland, Australia, where point‐of‐care ROTEM was introduced for paediatric patients in 2014. All children aged less than 18 years who had a ROTEM test during their presentation between January 2014 and December 2017 for a traumatic injury were included in the dataset. Other children with a record in the hospital's trauma registry in the same period were also screened for blood product usage. Data were collected for frequency of ROTEM testing, pathology and ROTEM results, blood product and antifibrinolytic use along with injury related data. Compliance with recommended treatment thresholds for detected coagulopathy was also reviewed.

Results

A total of 1039 children were listed in the trauma registry, including 167 children having a ROTEM test for trauma. Factors significantly associated with having a ROTEM test were older age, higher injury severity score (ISS >12) and penetrating injury. A result exceeding a treatment threshold was returned for 122 (73.1%) of 167 children, with hyperfibrinolysis identified in 88 (52.6%) of 167 and hypofibrinogenaemia identified in 54 (32.3%) of 167. Adherence with the recommended treatments for those children where a treatment threshold was exceeded was low in this cohort.

Conclusion

The use of ROTEM‐guided blood component replacement is an emerging practice in children for both traumatic and non‐traumatic bleeding. Targeted replacement of identified coagulation defects guided by rapid point‐of‐care testing is an emerging alternative to fixed‐ratio‐based protocols. Further research is required to validate treatment thresholds in the paediatric population and further investigate the clinical outcomes for patients as a result of early correction of trauma‐induced coagulopathy.

Changes in emergency department blood product use for major paediatric trauma following the implementation of a major haemorrhage protocol

OBJECTIVE

Fixed ratio blood product administration may improve outcomes in trauma patients with massive blood loss. The present study aimed to describe the impact of a major haemorrhage protocol (MHP) on the ratio of blood products administered for paediatric major trauma.

METHODS

Retrospective observational study in a state-designated paediatric major trauma centre in Melbourne, Australia. Children with major trauma who received blood products in the ED were identified from a hospital trauma registry. Blood product ratios before, during and after implementation of a hospital MHP were compared in consecutive 2 year blocks.

RESULTS

Over a 6 year period, 767 major trauma patients were identified, of whom 47 received blood products in the ED and were included in the analysis; 14 pre-MHP implementation, 24 during-MHP implementation and nine post-MHP implementation. No patients received blood products at a ratio of 1:1:1 for red blood cells:fresh frozen plasma:platelets, respectively, during any time period. In this cohort of predominantly blunt trauma, blood products were infrequently administered in the ED because of the low prevalence of massive blood loss. Coagulopathy and hypofibrinogenaemia were commonly observed, nearly half of included patients were managed operatively and one quarter did not survive their injuries.

CONCLUSION

The implementation of a MHP did not change the ratio of blood product administration in this cohort of patients because of the infrequency of massive blood loss. Future studies may focus on the impact of treating coagulopathy and hypofibrinogenaemia on patient-centred outcomes.