The place of fibrinogen concentrates in the management of perioperative bleeding: A position paper from the Francophone Working Group on Perioperative Haemostasis (GIHP)

Postpartum haemorrhage in high-resource settings: Variations in clinical management and future research directions based on a comparative study of national guidelines

OBJECTIVE

To compare guidelines from eight high-income countries on prevention and management of postpartum haemorrhage (PPH), with a particular focus on severe PPH.

DESIGN

Comparative study.

SETTING

High-resource countries.

POPULATION

Women with PPH.

METHODS

Systematic comparison of guidance on PPH from eight high-income countries.

MAIN OUTCOME MEASURES

Definition of PPH, prophylactic management, measurement of blood loss, initial PPH-management, second-line uterotonics, non-pharmacological management, resuscitation/transfusion management, organisation of care, quality/methodological rigour.

CONCLUSIONS

Our study highlights areas where strong evidence is lacking. There is need for a universal definition of (severe) PPH. Consensus is required on how and when to quantify blood loss to identify PPH promptly. Future research may focus on timing and sequence of second-line uterotonics and non-pharmacological interventions and how these impact maternal outcome. Until more data are available, different transfusion strategies will be applied. The use of clear transfusion-protocols are nonetheless recommended to reduce delays in initiation. There is a need for a collaborative effort to develop standardised, evidence-based PPH guidelines.

RESULTS

Definitions of (severe) PPH varied as to the applied cut-off of blood loss and incorporation of clinical parameters. Dose and mode of administration of prophylactic uterotonics and methods of blood loss measurement were heterogeneous. Recommendations on second-line uterotonics differed as to type and dose. Obstetric management diverged particularly regarding procedures for uterine atony. Recommendations on transfusion approaches varied with different thresholds for blood transfusion and supplementation of haemostatic agents. Quality of guidelines varied considerably.

Can machine learning provide preoperative predictions of biological hemostasis after extracorporeal circulation for cardiac surgery?

OBJECTIVES

The goal of this study was to improve decision making regarding the transfusion of patients at the end of extracorporeal circulation for cardiac surgery through machine learning predictions of the evolution of platelets counts, prothrombin ratio, and fibrinogen assay.

METHODS

Prospective data with information about patient preoperative biology and surgery characteristics were collected at Institut Mutualiste Montsouris Hospital (Paris, France) for 10 months (n = 598). For each outcome of interest, instead of arbitrarily choosing 1 machine learning algorithm, we trained and tested a variety of algorithms together with the super learning algorithm, a state-of-the-art ensemble method that aggregates all the predictions and selects the best performing algorithm (total, 137 algorithms). We considered the top-performing algorithms and compared them to more standard and interpretable multivariable linear regression models. All algorithms were evaluated through their root mean squared error, a measure of the average difference between true and predicted values.

RESULTS

The root mean squared error of the top algorithms for predicting the difference between pre- and postoperative platelet counts, prothrombin ratio, and fibrinogen assay were 38.27 × 10e9/L, 8.66%, and 0.44 g/L, respectively. The linear models had similar performances.

CONCLUSIONS

Our machine learning algorithms accurately predicted prothrombin ratio and fibrinogen assay and less accurately platelet counts. As such, our models could provide an aid-decision tool for anesthetists in an operating room; future clinical trials addressing this hypothesis are warranted.

Preoperative Fibrinogen Level and Bleeding in Liver Transplantation for End-stage Liver Disease: A Cohort Study

BACKGROUND

Liver transplantation is a high-risk surgery associated with important perioperative bleeding and transfusion needs. Uncertainties remain on the association between preoperative fibrinogen level and bleeding in this population.

METHODS

We conducted a cohort study that included all consecutive adult patients undergoing a liver transplantation for end-stage liver disease in 1 center. We analyzed the association between the preoperative fibrinogen level and bleeding-related outcomes. Our primary outcome was intraoperative blood loss, and our secondary outcomes were estimated perioperative blood loss, intraoperative and perioperative red blood cell transfusions, reinterventions for bleeding and 1-y graft and patient survival. We estimated linear regression models and marginal risk models adjusted for all important potential confounders. We used restricted cubic splines to explore potential nonlinear associations and reported dose-response curves.

RESULTS

We included 613 patients. We observed that a lower fibrinogen level was associated with a higher intraoperative blood loss, a higher estimated perioperative blood loss and a higher risk of intraoperative and perioperative red blood cell transfusions (nonlinear effects). Based on an exploratory analysis of the dose-response curves, these effects were observed below a threshold value of 3 g/L for these outcomes. We did not observe any association between preoperative fibrinogen level and reinterventions, 1-y graft survival or 1-y patient survival.

CONCLUSIONS

This study suggests that a lower fibrinogen level is associated with bleeding in liver transplantation. The present results may help improving the selection of patients for further studies on preoperative fibrinogen administration in liver transplant recipients with end-stage liver disease.

Fibrinogen concentrate and maternal outcomes in severe postpartum hemorrhage: A population-based cohort study with a propensity score-matched analysis

STUDY OBJECTIVE

Fibrinogen concentrate is used to treat severe postpartum hemorrhage despite limited evidence of its effectiveness in obstetric settings. We aimed to explore the association between its administration and maternal outcomes in women with severe postpartum hemorrhage.

DESIGN, SETTING AND PATIENTS

This secondary analysis of the EPIMOMS prospective population-based study, exploring severe maternal morbidity, as defined by national expert consensus (2012-2013, 182,309 deliveries, France), included all women with severe postpartum hemorrhage and transfused with red blood cells during active bleeding.

MEASUREMENTS

The primary endpoint was maternal near-miss or death, and the secondary endpoint the total number of red blood cells units transfused.

INTERVENTIONS

We studied fibrinogen concentrate administration as a binary variable and then by the timing of its administration. We used multivariable analysis and propensity score matching to account for potential indication bias.

MAIN RESULTS

Among the 730 women with severe postpartum hemorrhage and transfused, 313 (42.9%) received fibrinogen concentrate, and 142 (19.5%) met near-miss criteria or died. The risk of near-miss or death was not significantly lower among the women treated with fibrinogen concentrate than among those not treated, in either the multivariable analysis (adjusted RR = 1.03; 95% CI, 0.72-1.49; P = 0.855) or the propensity score analysis (RR = 0.85; 95% CI, 0.55-1.32; P = 0.477). Among women treated with fibrinogen concentrate, administration more than three hours after red blood cell transfusion started was associated with a higher risk of near-miss or death than administration before or within 30 min after the transfusion began (adjusted RR = 2.07; 95% CI, 1.10-3.89; P = 0.024). Results were similar for the secondary endpoint.

CONCLUSIONS

The use of fibrinogen concentrate in severe postpartum hemorrhage needing red blood cell transfusion during active bleeding is not associated with improved maternal outcomes.

Fibrinogen prophylaxis for reducing perioperative bleeding in patients undergoing radical cystectomy: A double-blind placebo-controlled randomized trial

OBJECTIVE

Excessive bleeding is an important complication of radical cystectomy. We aimed to assess whether preoperative administration of fibrinogen decreases perioperative bleeding and improves the outcome of radical cystectomy.

DESIGN

Double-blinded randomized trial with two parallel arms.

SETTING

The study was conducted in the department of surgery at a teaching hospital affiliated with a University of Medical Sciences.

PATIENTS

In total, 70 men undergoing radical cystectomy were randomized to fibrinogen (n = 35) and placebo-control groups. Mean (SD) age was 64.7 (7.4) years.

INTERVENTIONS

The intervention group received 2 g fibrinogen concentrate diluted in 100 ml distilled water, and the control group received 100 ml normal saline; both intravenously 15 ̶ 30 min before the start of the surgery.

OUTCOME MEASURES

The primary outcome was the amount of perioperative blood loss. The secondary outcomes were hemodynamic features and vital signs.

MAIN RESULTS

Fibrinogen significantly decreased the volume of blood loss (p < 0.001) and the total number of transfused packed-cell units per group (38 vs. 115 units); and compensated the decrease of HCO3 (p = 0.030), the mean arterial pressure (p < 0.001), hemoglobin O2 saturation (p = 0.001), heart rate (p < 0.001), and temperature (p < 0.001) throughout the surgery compared with the placebo. Patients in the fibrinogen group had shorter Intensive Care Unit (p = 0.001) and hospital (p < 0.001) stay. We did not find any adverse reaction in our patients receiving fibrinogen concentrate.

CONCLUSION

Fibrinogen concentrate reduces perioperative bleeding and the need for blood transfusion in radical cystectomy. It improves the outcomes of the surgery and decreases patients' length of stay in the healthcare system following radical cystectomy.

REGISTRATION

Iranian Registry of Clinical Trials (IRCT) http://www.irct.ir/, reference number: IRCT20191013045091N1.

ETHICS CODE

Shahid Beheshti University of Medical Sciences, reference number: IR.SBMU.RETECH.REC.1398.033.

Modelling the association between fibrinogen concentration on admission and mortality in patients with massive transfusion after severe trauma: an analysis of a large regional database

Background

The relationship between fibrinogen concentration and traumatic death has been poorly explored after severe trauma. Existing studies analysed this relationship in unselected trauma population, often considering fibrinogen concentration as a categorical variable. The aim of our study was to model the relationship between fibrinogen concentration and in-hospital mortality in severe trauma patients requiring massive transfusion using fibrinogen on admission as a continuous variable.

Methods

We designed a retrospective observational study based on prospectively collected data from 2009 to 2015 in seven French level-I trauma centres. All consecutive patients requiring a transfusion of at least 10 packed red blood cells (RBC) within 24 h were included. To assess the relationship between in-hospital death and fibrinogen concentration on admission, we performed generalized linear and additive models with death as a dependent variable. We also assessed the relationship between fibrinogen concentration below 1.5 g.L^− 1 and potential predictors.

Results

Within the study period, 366 patients were included. A non-linear relationship was found between fibrinogen concentration and death. Graphical modelling of this relationship depicted a negative association between fibrinogen levels and death below a fibrinogen concentration of 1.5 g.L^− 1. Predictors of low fibrinogen concentration (< 1.5 g.L^− 1) were systolic blood pressure, Glasgow coma scale and haemoglobin concentration on admission.

Conclusions

A complex and robust approach for modelling the relationship between fibrinogen and mortality revealed a critical fibrinogen threshold of 1.5 g.L^− 1 for severe trauma patients requiring massive transfusion. This trigger may guide the administration of procoagulant therapies in this context.