The Diagnostic Accuracy of EXTEM and HEPTEM Clotting Times Versus Standard Laboratory Tests in Cardiac Surgical Patients With and Without Normal FIBTEM Values

OBJECTIVES

There is extensive evidence to support the use of FIBTEM to identify hypofibrinogenemia during cardiac surgery, but less to support the use of EXTEM and INTEM clotting times (CTs) to identify other plasmatic coagulation factor deficiencies. The aim of the current study was to assess the diagnostic accuracy of EXTEM, INTEM, and HEPTEM CTs, using laboratory international normalized ratio (INR) and activated partial thromboplastin time (aPTT) as reference standards.

DESIGN

This was a retrospective diagnostic accuracy study.

SETTING

The work took place at a tertiary referral hospital.

PARTICIPANTS

A total of 176 cardiac surgical patients were enrolled.

INTERVENTIONS

INR, aPTT, ROTEM EXTEM, INTEM, and HEPTEM were measured post-heparin reversal after cardiopulmonary bypass.

MEASUREMENTS AND MAIN RESULTS

Sensitivity, specificity, and positive (PPVs) and negative predictive values (NPVs) for EXTEM CT >80 seconds and HEPTEM CT >280 seconds to detect INR ≥2.0, and INTEM CT >205 seconds to detect aPTT ≥38.5 seconds were calculated for all patients and the subset with normal FIBTEM A5 (>6 mm). The prevalence of INR ≥2.0 was 13%. EXTEM CT >80 seconds had a sensitivity of 1.00, specificity of 0.25, PPV of 0.17, and NPV of 1.00. HEPTEM CT >280 seconds had a sensitivity of 0.91, specificity of 0.38, PPV of 0.18, and NPV of 0.97. INTEM CT >205 seconds had a sensitivity of 0.97, specificity of 0.11, PPV of 0.57, and NPV of 0.75 for aPTT ≥38.5 seconds. These values were similar for the subset of patients with normal FIBTEM A5.

CONCLUSIONS

EXTEM CT >80 seconds and HEPTEM CT >280 seconds have high sensitivities and NPVs for INR >2.0, which would effectively "rule out" INR >2.0 as a cause for excessive bleeding. However, the low specificities and PPVs indicate they would be less effective in ruling it in. INTEM CT >205 seconds had low PPV and NPV in identifying aPTT >38.5 seconds.

Evaluation of Thromboelastography 6s prognostication of fibrinogen supplementation in pediatric cardiac surgery

BACKGROUND

Implementation of point-of-care tests is recommended to provide tailored substitution during cardiac surgery. The measurement and substitution of fibrinogen have gained particular interest since it is the first coagulation factor to become depleted during cardiac surgery. However, the prognostic ability of thromboelastography (TEG) 6s has not been evaluated in pediatric patients. The aim of the present study was to describe patient characteristics of infants receiving fibrinogen substitution during cardiac surgery and evaluate the prognostic ability of TEG6s after weaning off cardiopulmonary bypass (CPB).

METHODS

Infants undergoing congenital cardiac surgery with CPB were retrospectively included (n = 279) between January 2017 to July 2019. Patient and perioperative data were collected on the day of surgery until 6:00 AM the next morning. Hemostatic capacity was assessed with TEG6s. The efficacy of TEG-functional fibrinogen-maximal amplitude (TEG-FF-MA) measurements for the prediction of intraoperative bleeding, and thereby cryoprecipitate need, was evaluated by a sensitivity and specificity analysis.

RESULTS

Among 174 children with TEG-FF-MA data, 147 (84%) received cryoprecipitate intraoperatively. Cryoprecipitate administration was associated with younger age 66 (10-132) versus 98 (45-204) days (p = .044), higher RACHS-1 classification, and intraoperative bleeding 21 (11-47) versus 5 (3-13) ml/kg (p < .001, mean difference 29 ml/kg [CI: 8-50]). Median TEG-FF-MA values were lower in transfused children 7.6 (5.3-11.0) versus 10.5 (7.3-13.4) mm (p = .004, mean difference - 2.4 mm [CI: -4.1 to - 0.73]). The volume of cryoprecipitate was associated with bypass time, TEG-FF-MA values, and in particular intraoperative bleeding volumes. A TEG-FF-MA threshold of 10.0 mm, resulted in sensitivity: 74%, specificity: 56%, positive predictive value: 80%, and a negative predictive value of 47% for the prediction of intraoperative bleeding (>10 ml/kg) and consequently a need of cryoprecipitate transfusion.

CONCLUSION

Fibrinogen substitution in infants was associated with younger age and higher RACHS-1 category. The prognostic value of TEG6s was evaluated, and cryoprecipitate transfusion was related to TEG-FF-MA values, but also CPB-time, surgical complexity, and in particular excessive intraoperative bleeding. A clear-cut threshold for TEG-FF-MA is difficult to establish in infants undertaken congenital heart surgery.

An audit of the diagnostic accuracy of the ROTEM®sigma for the identification of hypofibrinogenaemia in cardiac surgical patients

The ROTEM®delta (TEM Innovations GmbH, Munich, Germany) has been used extensively worldwide for the assessment of coagulation in cardiac surgical patients. Recently, a new cartridge-based ROTEM device (ROTEM®sigma, TEM Innovations GmbH, Munich, Germany) has become available. In this paper we report an audit of the diagnostic accuracy of the ROTEM sigma for the identification of hypofibrinogenaemia in cardiac surgical patients. We hypothesised that the diagnostic accuracy of the ROTEMsigma for the identification of hypofibrinogenaemia would be in a similar range to that previously reported for the ROTEMdelta. Simultaneous blood samples for Clauss laboratory fibrinogen and ROTEMsigma FIBTEM measurements were obtained immediately after heparin reversal post-cardiopulmonary bypass in 200 adult cardiac surgical patients. The sensitivity, specificity, and positive and negative predictive values for FIBTEM A5 and A10 for the identification of hypofibrinogenaemia (Clauss fibrinogen <1.5 g/l) were calculated. The prevalence of hypofibrinogenaemia across the 200 patients was 8%. The mean sensitivity and specificity of FIBTEM A10 ≤8 mm for the identification of hypofibrinogenaemia were 0.75 and 0.90 respectively, which are in a similar range to that reported in several previous studies using the ROTEMdelta. For FIBTEM A5 ≤6 mm the values were 0.63 and 0.98 respectively. The predictive values were also in a similar range to those previously reported for the ROTEMdelta, with low false negative rates (2% for A10 ≤8 mm; 3% for A5 ≤6 mm). These findings support the use of the ROTEMsigma as an alternative to the ROTEMdelta for the identification of hypofibrinogenaemia post-cardiopulmonary bypass in cardiac surgical patients. However, further studies are required in other settings.

Pro-Con Debate: Viscoelastic Hemostatic Assays Should Replace Fixed Ratio Massive Transfusion Protocols in Trauma

Major trauma patients at risk of traumatic coagulopathy are commonly treated with early clotting factor replacement to maintain hemostasis and prevent microvascular bleeding. In the United States, trauma transfusions are often dosed by empiric, low-ratio massive transfusion protocols, which pair plasma and platelets in some ratio relative to the red cells, such as the "1:1:1" combination of 1 units of red cells, 1 unit of plasma, and 1 donor's worth of pooled platelets. Empiric transfusion increases the rate of overtransfusion when unnecessary blood products are administered based on a formula and not on at patient's hemostatic profile. Viscoelastic hemostatic assays (VHAs) are point-of-care hemostatic assays that provided detailed information about abnormal clotting pathways. VHAs are used at many centers to better target hemostatic therapies in trauma. This Pro/Con section will address whether VHA guidance should replace empiric fixed ratio protocols in major trauma.

The Year in Coagulation: Selected Highlights from 2020

This is the second annual review in the Journal of Cardiothoracic and Vascular Anesthesia to cover highlights in coagulation for cardiac surgery. The goal of this article is to provide readers with a focused summary from the literature of the prior year's most important coagulation topics. In 2020, this included a discussion covering allogeneic transfusion, antiplatelet and anticoagulant therapy, factor concentrates, coagulation testing, mechanical circulatory support, and the effects of coronavirus disease 2019.