Quantification of Fibrinolysis Using Velocity Curves Measured with Thromboelastometry in Children with Congenital Heart Disease

Standard and derived rotational thromboelastometry parameters for prediction of disseminated intravascular coagulation in septic patients

: Waiting for lab tests results for the calculation of disseminated intravascular coagulation (DIC) scores leads to unwanted delays in diagnosis. The use of rotational thromboelastometry (ROTEM) for this purpose would allow for a more rapid DIC diagnosis at the bedside. The aim of this study was to assess the ability of standard ROTEM parameters and calculated parameters from the ROTEM velocity curve to predict DIC. The retrospective observational study included 97 septic patients. Japanese Association for Acute Medicine score was used for DIC diagnosis and whole-blood ROTEM was performed at study inclusion. Univariate analysis revealed delayed coagulation initiation and propagation and reduced clot firmness and maximum elasticity in DIC patients compared with patients without DIC. To adjust for confounders, multivariable logistic regression models were created and fibrinogen levels, prothrombin time and ROTEM parameters such as maximum clot firmness, maximum clot elasticity (MCE) and total thrombus formation [area under the curve (AUC)] were identified as significant predictors of DIC. According to receiver operating characteristics analysis, MCE and total thrombus formation (AUC) were the most useful ROTEM parameters for DIC prediction. MCE less than 158 (73% sensitive, 80% specific) and AUC less than 6175 mm × 100 (73% sensitive, 76% specific) predicted DIC in septic patients. Both standard and derived ROTEM parameters are useful for rapid DIC prediction in septic patients, allowing the timely identification of patients with higher mortality risk which might benefit from additional therapies. Further studies are needed to assess the clinical relevance of these findings.

The current status of viscoelastic testing in septic coagulopathy

Sepsis can be associated with different degrees of coagulopathy, ranging from a mild activation of the coagulation system to disseminated intravascular coagulation (DIC). The evaluation of haemostasis in the context of sepsis is important since it has been shown that anticoagulant therapies were beneficial mainly in patients with sepsis-induced DIC, but not in the general population of septic patients. Sepsis-induced haemostatic disturbances are not adequately reflected by standard coagulation tests (SCTs) which only consider the plasmatic components of the haemostatic system and not the cellular components. In addition, SCTs only assess the initiation phase of coagulation and reflect the activity of pro-coagulant factors, but lack sensitivity for the anticoagulant drive and the fibrinolytic activity. Viscoelastic tests (VET) are whole-blood tests which can assess clot formation and dissociation, and the contribution of both plasmatic and cellular components with a shorter turnaround time compared to SCTs. The use of VET in septic patients has proved useful for the assessment of the fibrinolytic activity, detecting hypercoagulable status and for the diagnosis of DIC and mortality risk prediction. While having relevant advantages over SCTs, the VET also present some blind spots or limitations leaving space for future improvement by the development of new reagents or new viscoelastic parameters.

Thromboelastometric prediction of mortality using the kinetics of clot growth in critically ill septic patients

: Sepsis induces alterations in blood coagulation which are associated with mortality. Using rotational thromboelastometry (ROTEM), these states are often characterized by changes in parameters representing terminal clot lysis. However, the ROTEM changes are often subtle, making them difficult to recognize and interpret. The objective of this study is to evaluate a new ROTEM clot velocity parameter representing clot formation kinetics in septic ICU patients. We hypothesized that this time-based parameter was significantly different in critically ill septic survivors vs. nonsurvivors. This retrospective observational study included severe sepsis and septic shock patients having a minimum of two organ dysfunctions by Sequential Organ Failure Assessment criteria (study group), and a control group of healthy adults without infection . ROTEM with EXTEM activation was performed in all groups. The time from maximal clot formation velocity to zero velocity, representing the latter portion of time during active clot formation prior to achieving maximal clot firmness (t-AUCi) was calculated along with other ROTEM parameters and compared between septic survivors, nonsurvivors and healthy controls. A total of 76 septic patients, of which 26.3%, survived, were included in the study group, and 26 healthy control individuals were included in the control group. t-AUCi correlated with terminal clot lysis (P < 0.001), and was significantly prolonged in septic nonsurvivors compared with survivors and healthy controls (P < 0.001). t-AUCi also differentiated nonsurvivors vs. survivors among those patients having similar ROTEM lysis indices. t-AUCi was useful to differentiate critically ill septic patients, and could be useful to identify septic patients with high-risk of ICU mortality.

Effect of tranexamic acid on coagulation and fibrinolysis in women with postpartum haemorrhage (WOMAN-ETAC): protocol and statistical analysis plan for a randomized controlled trial

Background: Postpartum haemorrhage (PPH) is a leading cause of maternal death. Tranexamic acid has the potential to reduce bleeding and a large randomized controlled trial of its effect on maternal health outcomes in women with PPH (The WOMAN trial) is ongoing. We will examine the effect of tranexamic acid on fibrinolysis and coagulation in a subset of WOMAN trial participants.

Methods: Adult women with clinically diagnosed primary PPH after vaginal or caesarean delivery are eligible for inclusion in the WOMAN trial. In a sub-group of trial participants, blood samples will be collected at baseline and 30 minutes after the first dose of tranexamic acid or matching placebo.  Our primary objective is to evaluate the effect of tranexamic acid on fibrinolysis. Fibrinolysis will be assessed by measuring D-dimers and by rotational thromboelastometry (ROTEM). Secondary outcomes are international normalized ratio (INR), prothrombin time (PT), activated partial thromboplastin time (APTT), fibrinogen, haemoglobin and platelets. We aim to include about 180 women from the University College Hospital, Ibadan in Nigeria.

Discussion:  This sub-study of WOMAN trial participants should provide information on the mechanism of action of tranexamic acid in women with postpartum haemorrhage. We present the trial protocol and statistical analysis plan. The trial protocol was registered prior to the start of patient recruitment. The statistical analysis plan was completed before un-blinding.

Trial registration: The trial was registered: ClinicalTrials.gov, Identifier NCT00872469 https://clinicaltrials.gov/ct2/show/NCT00872469; ISRCTN registry, Identifier ISRCTN76912190 http://www.isrctn.com/ISRCTN76912190 (Registration date: 22/03/2012).

Noteworthy Literature in 2015

This article is a review of the literature published during the 12 months of 2015, which is of interest to the congenital cardiac anesthesiologist. While the review is not exhaustive, it identifies 7 themes in the literature for 2015 and cites 78 peer-reviewed publications.

Assessment of coagulation profile by thromboelastometry in adult patients with cyanotic congenital heart disease

BACKGROUND

Patients with cyanotic congenital heart disease (CCHD) have an increased risk of bleeding and thrombotic complications. Prolonged conventional coagulation screening parameters, such as activated partial thromboplastin time or prothrombin time, are reported in less than 20% of CCHD patients.

METHODS

The aim of this study was to determine the haemostatic abnormalities in 32 adult patients with CCHD by rotation thromboelastometry (ROTEM) with assessment of coagulation dynamic properties, as a guide for perioperative prophylaxis or haemostatic therapy. The control group consisted of 35 healthy subjects.

RESULTS

Our results suggest that CCHD patients, in comparison to healthy controls, had a tendency to hypocoagulate with delayed activation of haemostasis and clot formation, initiated by both intrinsic and extrinsic activators. The growth of the clot was slower and the clot firmness was decreased, which may additionally contribute to bleeding diathesis. Moreover, the clot lysis readings suggest higher clot stability in the CCHD group. All velocity parameters were markedly lower in the CCHD patients, indicating a decreased rate of clot formation. Although coagulation tests and platelet count were normal, the usefulness of rotation thromboelastometry in monitoring or guiding therapy in CCHD patients is demonstrated.

CONCLUSION

In conclusion, our results provide new insights into the data on hypocoagulation with impaired clot lysis in adult CCHD patients as determined by ROTEM. Our findings may assist in determining the optimal management of patients with CCHD undergoing surgery.