Low Preoperative Fibrinogen Plasma Concentration Is Associated With Excessive Bleeding After Cardiac Operations

Analyzing and modeling massive transfusion strategies and the role of fibrinogen-How much is the patient actually receiving?

BACKGROUND

Hemorrhage is a leading cause of preventable death in trauma, cardiac surgery, liver transplant, and childbirth. While emphasis on protocolization and ratio of blood product transfusion improves ability to treat hemorrhage rapidly, tools to facilitate understanding of the overall content of a specific transfusion strategy are lacking. Medical modeling can provide insights into where deficits in treatment could arise and key areas for clinical study. By using a transfusion model to gain insight into the aggregate content of massive transfusion protocols (MTPs), clinicians can optimize protocols and create opportunities for future studies of precision transfusion medicine in hemorrhage treatment.

METHODS

The transfusion model describes the individual round and aggregate content provided by four rounds of MTP, illustrating that the total content of blood elements and coagulation factor changes over time, independent of the patient's condition. The configurable model calculates the aggregate hematocrit, platelet concentration, percent volume plasma, total grams and concentration of citrate, percent volume anticoagulant and additive solution, and concentration of clotting factors: fibrinogen, factor XIII, factor VIII, and von Willebrand factor, provided by the MTP strategy.

RESULTS

Transfusion strategies based on a 1:1:1 or whole blood foundation provide between 13.7 and 17.2 L of blood products over four rounds. Content of strategies varies widely across all measurements based on base strategy and addition of concentrated sources of fibrinogen and other key clotting factors.

DISCUSSION

Differences observed between modeled transfusion strategies provide key insights into potential opportunities to provide patients with precision transfusion strategy.

Hemostatic effects of a dextran-based priming solution for cardiopulmonary bypass: A secondary analysis of a randomized clinical trial

INTRODUCTION

Intravascular fluids administered to patients may influence hemostasis. In patients undergoing cardiac surgery with cardiopulmonary bypass, the heart-lung machine is primed with 1300 ml of fluid. We assessed postoperative coagulation and platelet function in patients randomized to two different priming solutions, one colloid-based (dextran 40) and one crystalloid-based.

MATERIALS AND METHODS

Eighty-four elective cardiac surgery patients were randomized to either a dextran-based prime or Ringer's acetate with added mannitol. Blood samples were collected before, and 2 and 24 h after cardiopulmonary bypass. Coagulation was assessed by standard coagulation tests and rotational thromboelastometry. Platelet function was assessed with impedance aggregometry. Bleeding volumes and transfusion requirements were recorded.

RESULTS

Comparing the groups 2 h after bypass, the dextran group showed lower hemoglobin concentration, hematocrit, platelet count, and fibrinogen concentration, and higher INR and aPTT, as well as longer clot formation time (+41 ± 21 % vs. +8 ± 18 %, p < 0.001) and a larger reduction in fibrinogen-dependent clot strength (-37 ± 12 % vs. -7 ± 20 %, p < 0.001). Adenosine diphosphate-dependent platelet activation was reduced in the dextran group but not in the crystalloid group 2 h after bypass (-14 ± 29 % vs. -1 ± 41 %, p = 0.041). No significant between-group differences in hemostatic variables remained after 24 h, and no significant differences in perioperative bleeding volumes, re-explorations for bleeding, or transfusion rates were observed.

CONCLUSIONS

Compared to a crystalloid solution, a dextran-based prime had measurable negative impact on hemostatic variables but no detectable increase in bleeding volume or transfusion requirements in cardiac surgery patients.

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.

Preoperative fibrinogen level and postcardiac surgery morbidity and mortality rates

BACKGROUND

High preoperative fibrinogen levels are associated with reduced bleeding rates after cardiac surgery. Fibrinogen is directly involved in inflammatory processes and is a cardiovascular risk factors. Whether high fibrinogen levels before cardiac surgery are a risk factor for mortality or morbidity remains unclear.

AIMS

This study aimed to examine the association between preoperative fibrinogen levels and mortality and morbidity rates after cardiac surgery.

SETTINGS AND DESIGN

This is a single-center retrospective study.

MATERIAL AND METHODS

Patients (n = 1628) were divided into high (HFGr) and normal (NFGr) fibrinogen level groups, based on the cutoff value of 3.3 g/L, derived from the receiver operating characteristic (ROC) curve analysis. The primary outcome was the 30-day mortality rate. The rates of postoperative complications, including postoperative bleeding and transfusion rates, were examined.

STATISTICAL ANALYSIS

Between-group comparisons were performed with the Mann-Whitney U test and Chi-squared test, as suitable. Model discriminative power was examined with the area under the ROC curve.

RESULTS

The HFGr and NFGr included 1103 and 525 patients, respectively. Mortality rate was higher in the HFGr than in the NFGr (2.7% vs. 1.1%, P = 0.04). The 12-h bleeding volume (280 mL [195-400] vs. 305 mL [225-435], P = 0.0003) and 24-h bleeding volume values (400 mL [300-550] vs. 450 mL [340-620], P &lt; 0.0001) were lower in the HFGr than in the NFGr. However, the rate of red blood cell transfusion during hospitalization was higher in the HFGr than in the NFGr (21.7% vs. 5.9%, P = 0.0103). Major complications were more frequent in the HFGr than in the NFGr.

CONCLUSION

High fibrinogen levels were associated with reduced postoperative bleeding volume and increased mortality and morbidity rates.

Evaluation of plasma fibrinogen levels before and after coronary artery bypass graft surgery and its association with the need for blood products

Background:

The present study investigated the plasma level of fibrinogen before and after removing the pump in coronary artery bypass graft (CABG) surgery and its relationship with the need for blood products.

Materials and Methods:

The present study was performed on 60 patients who were candidates for CABG surgery. The fibrinogen level of these patients was assessed and recorded before surgery and immediately after removing the pump. In addition, their hemoglobin level was recorded before the operation and 2 h after. In addition, the number and type of blood products transfusion were recorded intraoperatively and postoperatively and also at the intensive care unit.

Results:

Patients’ fibrinogen level after removing the pump with the mean of 130.53 ± 122.01 mg/dl decreased significantly compared to before surgery with the mean of mg/dl 224.95 ± 132.88 mg/dl (P < 0.001). In addition, the prognostic value of fibrinogen after removing the pump in determining the postoperative need of blood transfusion showed that the cut-off value of fibrinogen was < 196 mg/dl with a sensitivity of 16.82% and specificity of 80%, but it was not statistically significant (area under the curve [95% confidence interval]: 0.519 [0.350–0.689]; P = 0.825).

Conclusion:

According to the results of the present study, due to significant changes in fibrinogen levels after removing the pump compared to preoperation, it seems that this factor can play an important role in prognosis of the need to postoperative blood transfusion, although the prognostic value and the critical point mentioned in our study was not significant and it is required to do further studies.

Fibrinogen and Bleeding in Adult Cardiac Surgery: A Review of the Literature

Background: Fibrinogen is a substrate for blood clots formation. In cardiac surgery, a number of different mechanisms lead to a decrease in fibrinogen levels and consequent impaired haemostasis. Patients undergoing cardiac surgery are therefore frequently exposed to blood loss and allogeneic blood transfusion, which are risk factors associated with morbidity and mortality. Thus, particular efforts in fibrinogen management should be made to decrease bleeding and the need for blood transfusion. Therefore, fibrinogen remains an active focus of investigations from basic science to clinical practice. This review aims to summarise the latest evidence regarding the role of fibrinogen and current practices in fibrinogen management in adult cardiac surgery. Methods: The PubMed database was systematically searched for literature investigating the role and disorders of fibrinogen in cardiac surgery and diagnostic and therapeutic procedures related to fibrinogen deficiency aimed at reducing blood loss and transfusion requirements. Clinical trials and reviews from the last 10 years were included. Results: In total, 146 articles were analysed. Conclusion: The early diagnosis and treatment of fibrinogen deficiency is crucial in maintaining haemostasis in bleeding patients. Further studies are needed to better understand the association between fibrinogen levels, bleeding, and fibrinogen supplementation and their impacts on patient outcomes in different clinical settings.

A comparison of the in vitro effects of three fibrinogen concentrates on clot strength in blood samples from cardiac surgery patients

BACKGROUND

Fibrinogen concentrate is used clinically to improve hemostasis in bleeding patients. We investigated and compared the efficacy of three commercially available fibrinogen concentrates to improve clot strength in blood samples from cardiac surgery patients.

OBJECTIVES

Postoperative blood samples were collected from 23 cardiac surgery patients. Samples were each divided into four vials, each supplemented with 1.125 mg of fibrinogen of one of three fibrinogen concentrates (RiaSTAP^® , Fibryga^® , FibCLOT^® ), or placebo. The fibrinogen dose corresponded to 2.5 g per 70 kg of body weight. Clot strength after supplementation was assessed in duplicate with rotational thromboelastometry (ROTEM^® ) using FIBTEM maximum clot firmness, EXTEM clot formation time, and maximum clot firmness assays.

RESULTS

In vitro fibrinogen concentrate supplementation of the samples resulted in higher plasma fibrinogen concentrations and improved clot strength with all three concentrates. Supplementation with FibCLOT increased FIBTEM maximum clot firmness (+46% [25th-75th percentile 35-55] compared to placebo) significantly more than did supplementation with Fibryga (+26% [21-35]) and RiaSTAP (+29% [22-47], p < .001). FibCLOT supplementation also shortened EXTEM clot formation time and increased EXTEM maximum clot firmness to a greater extent than did the other concentrates (both p < .001).

CONCLUSIONS

At the selected dose, FibCLOT was more effective than Fibryga and RiaSTAP in restoring clot strength in postoperative blood samples from cardiac surgery patients. These results may have implications for the choice of fibrinogen concentrate and dosing.

Hepatic dysfunction in patients who received acute DeBakey type I aortic dissection repair surgery: incidence, risk factors, and long-term outcomes

BACKGROUND

Hepatic dysfunction (HD) increases the morbidity and mortality rates after cardiac surgery. However, few studies have investigated the association between HD and acute DeBakey type I aortic dissection (ADIAD) surgery. This retrospective study aimed to identify risk factors for developing HD in patients who received acute type I aortic dissection repair and its consequences.

METHODS

A total of 830 consecutive patients who received ADIAD surgery from January 2014 to December 2019 at our center were screened for this study. The End-Stage Liver Disease (MELD) score more than 14 was applied to identify postoperative HD. Logistic regression model was applied to identify risk factors for postoperative HD, Kaplan-Meier survival analysis and Cox proportional hazards regression assay were conducted to analyze the association between HD and postoperative long-term survival.

RESULTS

Among 634 patients who eventually enrolled in this study, 401 (63.2%) experienced postoperative HD with a 30-Day mortality of 15.5%. Preoperative plasma fibrinogen level (PFL) [odds ratio (OR): 0.581, 95% confidence interval (CI): 0.362-0.933, P = 0.025], serum creatinine (sCr) on admission (OR: 1.050, 95% CI 1.022-1.079, P < 0.001), cardiopulmonary bypass (CPB) time (OR: 1.017, 95% CI 1.010-1.033, P = 0.039), and postoperative mechanical ventilation (MV) duration (OR: 1.019, 95% CI 1.003-1.035, P = 0.020) were identified as independent risk factors for developing postoperative HD by multivariate analyses. In addition, the Kaplan-Meier analysis indicated that the long-term survival rate was significantly different between patients with or without postoperative HD. However, the hazard ratios of long-term survival for these two groups were not significantly different.

CONCLUSIONS

HD was a common complication after ADIAD surgery and associated with an increasing 30-Day mortality rate. Decreased PFL, elevated sCr, prolonged CPB duration, and longer postoperative MV time were independent risk factors for postoperative HD.

Fibrinogen Level Combined With Platelet Count for Predicting Hemorrhagic Transformation in Acute Ischemic Stroke Patients Treated With Mechanical Thrombectomy

A serious complication of acute ischemic stroke (AIS) after mechanical thrombectomy (MT) is hemorrhagic transformation (HT), which is potentially associated with clinical deterioration. This study examined predictors of HT following MT in AIS patients. Patients with AIS due to large artery occlusion in the anterior circulation, treated with MT and successfully recanalized (modified Thrombolysis in Cerebral Infarction score 2b/3), were studied retrospectively. HT was evaluated by computed tomography (CT) 24 h after MT and was diagnosed and classified into parenchymal hematoma (PH) and hemorrhagic infarction (HI). Multivariate logistic regression models were used to determine the risk factors for HT. Receiver operating characteristic (ROC) curve analysis was performed to determine the predictive utility of risk factors for HT. We enrolled 135 patients: 49 in the HT group and 86 in the non-HT group. The two groups differed significantly in baseline fibrinogen levels (p = 0.003) and platelet counts (p = 0.006). Multivariate logistic regression analyses showed that lower fibrinogen levels [odds ratio (OR), 0.41; 95% CI, 0.23–0.72; p = 0.002] and platelet counts (OR, 0.58; 95% CI, 0.33–0.99; p = 0.048) were independently associated with a higher risk of HT. Together, the binary variates fibrinogen and platelets well-predicted HT (area under the curve, 0.703; specificity, 77.9%; sensitivity, 55.1%). The combination of fibrinogen <2.165 g/L and platelets <171.5 × 10⁹/L was the strongest predictor of HT (OR, 23.17; 95% CI, 5.75–126.80; p < 0.0001). Our study suggests that lower baseline fibrinogen levels and platelet counts may be risk factors for HT in AIS patients following MT and reperfusion. Specifically, the combination of fibrinogen level and platelet count may predict the risk of HT after MT in these patients.

Dynamic assessment of plasma clotting in samples with distinct fibrinogen concentrations using impulsive acoustic radiation force

While some diseases reduce fibrinogen concentration, others increase the amount of this clotting factor in the blood. Some studies have shown that the fibrinogen concentration in the blood is related to the stiffness of the formed clot. Hence, the aim of this study was to employ an ultrasonic method based on impulsive acoustic radiation force (IARF) to identify the fibrinogen concentration (coagulation factor I) in a plasma sample by means of peak-displacement (PD), time of peak-displacement (TPD), and shear modulus (μ) as well as to identify the change of plasma samples during the clot formation process. The IARF-based ultrasonic system transmitted bursts with a frequency of 2.03 MHz, duration of 246.31 µs, amplitude of 118 VPP, and pulse with 1.25 Hz repetition frequency to generate an IARF on a glass sphere (2.99 mm in diameter and 2500 kg/m3 in density) embedded in a plasma sample, causing a displacement that was monitored by a pulse-echo system with a center frequency of 4.89 MHz. The values of the shear moduli were 124.14 ± 3.02, 556.99 ± 11.76, and 670.39 ± 9.77 Pa, for fibrinogen concentrations of 1.2, 2.4, and 3.6 g/L 20 to 36 min after the beginning of the coagulation process. The TPD values obtained in the same period were 5.28 ± 0.09, 3.03 ± 0.02, and 2.83 ± 0.01 s. The results indicate that an IARF-based ultrasonic system can be used clinically because it uses small amounts of plasma and has the ability to detect differences in PD, TPD, and μ as a function of fibrinogen concentrations.

Thrombotic activation before and after total hip arthroplasty. A prospective cohort study

Background

Total hip arthroplasty (THA) causes acute blood loss. It may lead to a deficiency in coagulation factors, which, in turn, may lead to increased bleeding during the postoperative period.

Methods

Thirty patients (18 women) with a mean age of 67 years (range: 63–72 years) participated in this prospective diagnostic study. THA was performed without tranexamic acid administration in the perioperative period. Activities of clotting factors II, VIII, X, and fibrinogen concentration were evaluated before surgery, 6 hours after the procedure, 2, 4, and 6 days after the operation. All laboratory tests were performed using ACL TOP 500 CTS analyzer.

Results

No thromboembolic complications were noted during hospitalization. Mean fibrinogen concentration was 366 mg/dL before surgery, which decreased to 311 mg/dL 6 hours after the operation and peaked at 827 mg/dL on the 4th day after the procedure. Activities of factors II and X decreased on the second and fourth days after surgery. Although the activity of factor VIII decreased after the procedure, it remained within the normal range. Increased baseline fibrinogen concentrations were observed in 6 out of 30 (20%) patients. Mean blood loss was 1332 mL (range, 183–2479 mL) and did not correlate with changes in clotting factor activities.

Conclusions

In patients undergoing THA, fibrinogen acts as an acute-phase protein. Activities of clotting factors II and X normalize within 6 days, and although the activity of factor VIII decreases, it remains within the normal range.

Trial registration

The study was pre-registered May 1st, 2020 on ClinicalTrials.gov

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.

Trigger and Target for Fibrinogen Supplementation Using Thromboelastometry (ROTEM) in Patients Undergoing Open Thoraco-Abdominal Aortic Aneurysm Repair

OBJECTIVE

To determine the relationship between the value of fibrinogen assessed by the FIBTEM clot amplitude at 10 minutes (A10 FIBTEM) measured on admission to the intensive care unit (ICU) and the amount of drainage output at 24 hours, to investigate whether the A10 FIBTEM predicts severe bleeding (SB), and to define A10 FIBTEM thresholds to prevent (trigger) and treat (target) severe bleeding by fibrinogen supplementation.

METHODS

In a single centre, retrospective observational study, 166 patients underwent elective open thoraco-abdominal aortic aneurysm (TAAA) repair between March 2016 and January 2019. Exclusion criteria were emergency, congenital, or acquired coagulopathy, or administration of P₂Y₁₂ inhibitor antiplatelet agents in the five days before surgery. All patients were managed intra-operatively and post-operatively according to a rotational thromboelastometry driven transfusion protocol. The principal endpoint was a composite outcome, which included bleeding, large volume transfusion, and re-operation.

RESULTS

FIBTEM clot amplitude after 10 minutes measured on ICU admission and post-operative bleeding at 24 hours showed an inverse linear relationship (R² = .03; p = .026). Performance of A10 FIBTEM in predicting SB evaluated by Receiving Operating Curve analysis showed an area under the curve of 0.63 (95% CI 0.56 - 0.70; p = .026) with a best cutoff of 9 mm. An A10 FIBTEM of 3 mm was the cutoff associated with a positive predictive value of 50%, while an A10 FIBTEM of 9 mm showed a negative predictive value of 92%. On multivariable analysis, an A10 FIBTEM ≤ 3 mm remained independently associated with SB.

CONCLUSION

The present investigation shows for the first time in a population undergoing open TAAA repair that an A10 FIBTEM ≤ 3mm on ICU admission is associated with post-operative severe bleeding. Trigger and target values for fibrinogen supplementation, based on A10 FIBTEM, have been provided. The transferability and reliability of these cutoff values require further study.

Fibrin clot susceptibility to lysis is impaired after on-pump coronary artery by-pass grafting with tranexamic acid: clinical implications

Coronary artery bypass grafting (CABG) done on-pump may cause a significant blood loss. Low fibrinogen is associated with perioperative bleeding. The influence of cardiopulmonary bypass on fibrin clot properties is poorly investigated. We studied 55 patients with isolated coronary artery disease on aspirin undergoing on-pump CABG with tranexamic acid. Fibrinogen levels, fibrinolytic capacity expressed as clot lysis time (CLT), thrombin generation potential and platelet count were assessed before and after the surgery (prior to admission to the intensive care unit). A postoperative drop in haemoglobin (-30% from baseline), haematocrit (-31% from baseline) and platelet count (-42% from baseline) was observed (all, P < 0.0001). Postoperative fibrinogen level was lower by 57%, compared with preoperative value (1.5 [1.3-1.8] vs. 3.5 [2.8-3.9] g/l, P < 0.0001). Postoperative CLT was longer by 48 min, compared with preoperative (182 [170-218] vs. 134 [122-165] min, P < 0.0001). Thrombin generation was impaired postoperatively: both lag time and time to peak thrombin were prolonged by 44 and 45%, respectively, whereas endogenous thrombin potential and peak thrombin generation decreased by 45 and 78%, respectively (all P < 0.0001). Median postoperative drainage at 12 h was 400 [290-570] ml. Predictors of blood loss at 12 h identified in multivariable linear regression model adjusted for sex and preoperative fibrinogen level were: BMI (b = -23.4, P = 0.048) and postoperative CLT (b = -2.4, P = 0.042). Despite decreased fibrinogen levels after on-pump CABG with tranexamic acid, fibrin clot susceptibility to lysis is impaired, as reflected by prolonged CLT. Postoperative CLT is associated with mediastinal drainage at 12 h.

Preoperative plasma fibrinogen level and transfusion in cardiac surgery: a biphasic correlation

Coagulopathic bleeding is a serious complication of cardiac surgery. A very low preoperative plasma fibrinogen level (PFL) has been previously described as a risk factor for red blood cell (RBC) transfusion in the perioperative setting. Nevertheless, contradictory results have been published concerning preoperative fibrinogen infusion to decrease RBC transfusion. These results highlight the need for a better description of the relation between preoperative PFL and RBC transfusion. In this single-centre retrospective study, we showed that both high and low PFLs are associated with an increase in RBC transfusion. A pro-inflammatory preoperative status could be involved in the association between high PFL and the increase in RBC transfusion. This non-linear relation between PFL and RBC transfusion could explain the difficulty of decreasing postoperative bleeding using only an algorithm aimed at increasing preoperative PFL.

U-shaped relationship between pre-operative plasma fibrinogen levels and severe peri-operative bleeding in cardiac surgery

BACKGROUND

An inverse linear relationship has been reported between pre-operative fibrinogen levels and postoperative blood loss in cardiac surgery. However, recently high pre-operative fibrinogen levels have also been reported to be associated with increased blood transfusion and re-operation.

OBJECTIVE

We tested the hypothesis that the relationship between pre-operative fibrinogen levels and severe peri-operative bleeding is not linear.

DESIGN

A large-scale (n = 3883) single-centre retrospective study.

SETTING

A tertiary care teaching hospital.

PATIENTS

We analysed data from our institutional database which includes all patients above 18 years who underwent on-pump cardiac surgery through a sternotomy between September 2010 and May 2014.

MAIN OUTCOME MEASURES

Peri-operative severe bleeding adapted from the Universal Definition of Peri-operative Bleeding, class 3 or 4. The relationship between pre-operative fibrinogen levels and peri-operative severe bleeding was analysed by binary logistic regression. A cubic B-spline transformation was used to estimate the relationship between pre-operative fibrinogen level associated with excessive peri-operative bleeding.

RESULTS

Severe peri-operative bleeding was observed in 957 (24.6%) patients. An L-shaped relationship was observed between pre-operative fibrinogen levels and 24-h postoperative blood loss. The relationship between pre-operative fibrinogen levels and severe peri-operative bleeding (i.e. Universal Definition of Peri-operative Bleeding class 3 or 4) was U-shaped: the risk of severe peri-operative bleeding bottomed at 3.3 g l when the upward sloping curve started at 5.8 g l with a steeper increase above 8.2 g l.

CONCLUSION

We reported a U-shaped relationship between severe peri-operative bleeding and pre-operative fibrinogen levels. While a low-level of fibrinogen appears to be associated with a high risk of bleeding, a high level does not necessarily protect the patient against such a risk and could even be a risk factor for peri-operative bleeding.

The prophylactic use of fibrinogen concentrate in high-risk cardiac surgery

BACKGROUND

Perioperative blood loss is a major contributor to morbidity and mortality in cardiac surgery. Plasma fibrinogen levels play an essential role in hemostasis and deplete quickly during hemorrhage. The objective of this study was to determine whether prophylactic fibrinogen concentrate administration lowers overall blood product transfusion requirements in high-risk cardiac surgery in patients with low fibrinogen plasma levels.

METHODS

The study was performed in a prospective, randomized, and double-blinded design. The investigation included 62 patients undergoing elective, high-risk cardiac surgery. After weaning from cardiopulmonary bypass and reversal of heparin patients received either fibrinogen concentrate or placebo. The primary outcome variable was overall blood product usage 24 hours after intervention.

RESULTS

The fibrinogen group received numerically fewer total units of blood products than the placebo group, but the difference was not statistically or clinically significant (for groups n = 27; n = 29 and 19 vs 37 units, respectively, P = .908). The overall transfusion rate in both groups was significantly lower than the institutional average suggested (fibrinogen group 26%, placebo group 28%). The fibrinogen group showed significantly higher fibrinogen levels (2.38 vs 1.83 g/L (end of surgery), P < .001; 3.33 vs 2.68 g/L (12 hours after intervention), P = .003) and improved viscoelastic coagulation parameters (FIBTEM MCF, 27 vs 23 mm, P = .022).

CONCLUSION

This randomized, controlled trial demonstrates that point-of-care guided and prophylactic treatment with fibrinogen concentrate does not reduce transfusion of blood products in a setting of unexpectedly low transfusion rate as tested in this cohort, but may improve coagulation parameters in the setting of high-risk cardiac surgery.

Effects of storage over a 36-month period on coagulation factors in a canine plasma product obtained by use of plasmapheresis

OBJECTIVE

To evaluate stability of coagulation factors in canine plasma obtained by use of plasmapheresis and stored over a 36-month period.

SAMPLE

Canine plasma obtained by use of plasmapheresis acquired from a commercial blood bank.

PROCEDURES

Coagulation testing for fibrinogen concentration and activity of factors II, V, VII, VIII, and IX and von Willebrand factor was performed on canine plasma obtained by use of plasmapheresis. Samples were obtained for testing at 6-month intervals from plasma stored for up to 36 months.

RESULTS

A simple mixed linear regression model was created for each analysis. Median value for the fibrinogen concentration was > 150 mg/dL for all time points, except at 467, 650, and 1,015 days of storage. Median value for factor VIII was > 70% only at 650 days. Median value for factor V was > 50% through 650 days. Median value for factors VII and X was > 50% through 833 days, and median value for factors II and VII was > 50% through 1,015 days. Median value for von Willebrand factor was > 50% for the entire study (1,198 days). Median value for factor X was always < 50%.

CONCLUSIONS AND CLINICAL RELEVANCE

Coagulation factors degraded over time at variable rates, and all labile factors remained at > 50% activity for longer than 1 year. Plasma collected by plasmapheresis potentially offers prolonged life span of some clotting factors. Plasmapheresis is an acceptable form of canine plasma collection for transfusion purposes, and further studies should be performed to determine all of its benefits.

A Low-dose human fibrinogen is not effective in decreasing postoperative bleeding and transfusion requirements during cardiac surgery in case of concomitant clinical bleeding and low FIBTEM values: A retrospective matched study

Background

Studies evaluating the hemostatic effects of fibrinogen administration in cardiac surgery are not conclusive.

Aims

We investigated whether the use of a low-dose human fibrinogen in case of clinical bleeding after protamine administration and concomitant low FIBTEM values is effective in reducing postoperative bleeding. Secondary end-point was to investigate the consumption of allogeneic blood products.

Setting and Design

This was a retrospective matched study conducted at university hospital.

Materials and Methods

Among 2257 patients undergoing surgery with cardiopulmonary (CPB) bypass, 73 patients received a median dose of 1 g human fibrinogen (ROTEM-Fibri group). This group was matched with 73 patients who had not received human fibrinogen (control group) among 390 patients having undergone surgery at the moment FIBTEM analysis was unavailable.

Statistical Analysis

Matching was performed for the type and the presence of redo surgery. McNemar and Wilcoxon paired tests were used to respectively compare the categorical and quantitative variables.

Results

The CPB bypass time was significantly higher in the ROTEM-Fibri group (P = 0.006). This group showed significantly higher bleeding in the first 12 and 24 h postoperatively (P < 0.001) and required significantly more transfusion of blood products (P < 0.001) and surgical revision (P = 0.007) when compared with the control group. There was no significant difference in the number of thromboembolic complications.

Conclusions

These results show that the administration of 1 g of fibrinogen based on low-FIBTEM values and clinical bleeding after protamine administration does not stop bleeding and the need for transfusion of allogeneic blood products.

Effects of fibrinogen and platelet transfusion on coagulation and platelet function in bleeding cardiac surgery patients

BACKGROUND

Excessive bleeding is a significant problem in cardiac surgery. Fibrinogen and platelet concentrate transfusion are used clinically to improve haemostasis and reduce bleeding but little is known about their functional effects on coagulation and platelet function in patients with ongoing bleeding.

METHODS

Forty-two patients with ongoing bleeding after cardiac surgery were included in an observational study. Patients received either fibrinogen concentrate (n = 16), platelet concentrate (n = 12), or both fibrinogen and platelets (n = 14), median doses 2 g fibrinogen and 2 units platelets given at one occasion. Blood samples were collected before and after transfusion. Coagulation (clotting time and clot stability) was analysed with rotational thromboelastometry, and platelet function with impedance aggregometry. In addition, platelet count and fibrinogen concentration was measured. Chest drain output was measured before and after the transfusion.

RESULTS

Fibrinogen infusion resulted in an increase in fibrinogen concentration and clot stability (P = 0.001), but had no effect on platelet aggregation. Platelet transfusion did not significantly affect coagulation, but improved arachidonic acid- and TRAP-induced platelet aggregation (P = 0.017 and 0.034 respectively) and increased platelet count. Combined fibrinogen and platelet transfusion shortened clotting time (P = 0.005) and increased clot stability (P = 0.001), and improved arachidonic acid- and TRAP-induced platelet aggregation (P = 0.004 and 0.016 respectively), and increased fibrinogen concentration and platelet count. The median bleeding volume was 150 (25th-75th percentile 70-240) mL/h before, and 60 (40-110) mL/h after transfusion of fibrinogen and/or platelet concentrate (P < 0.001).

CONCLUSION

The results demonstrate improved coagulation and platelet function following fibrinogen and platelet transfusion in patients bleeding after cardiac surgery.

Diagnostic evaluation of risk for bleeding in cardiac surgery with extracorporeal circulation

OBJECTIVE

to identify the risk factors associated with cases of excessive bleeding in patients submitted to cardiac surgery with extracorporeal circulation.

METHOD

case-control study on the factors of risk for bleeding based on the analysis of data from the medical charts of 216 patients submitted to cardiac surgery with elective extracorporeal circulation during a three-year period.

RESULTS

variables that are commonly associated with excessive bleeding in studies in the field were analyzed, and the following were considered as risk factors for the nursing diagnosis "risk for bleeding" (00206) in cardiac surgery with extracorporeal circulation: Body mass index lower than 26.35kg/m² (Odds ratio = 3.64); Extracorporeal circulation longer than 90 minutes (Odds ratio = 3.57); Hypothermia lower than 32°C (Odds ratio = 2.86); Metabolic acidosis (Odds ratio = 3.50) and Activated partial thromboplastin time longer than 40 seconds (Odds ratio= 2.55).

CONCLUSION

such variables may be clinical indicators of an operational nature for a better characterization of the risk factor "treatment regimen" and a refinement of knowledge related to coagulopathy induced by extracorporeal circulation, which is currently presumably incorporated into the "treatment regimen" category of the nursing diagnostic classification by NANDA International, Inc.

Factors associated with the increased bleeding in the postoperative period of cardiac surgery: A cohort study

AIMS AND OBJECTIVES

To identify factors associated with the increased bleeding in patients during the postoperative period after cardiac surgery.

BACKGROUND

Bleeding is among the most frequent complications that occur in the postoperative period after cardiac surgery, representing one of the major factors in morbidity and mortality. Understanding the factors associated with the increased bleeding may allow nurses to anticipate and prioritise care, thus reducing the mortality associated with this complication.

DESIGN

Prospective cohort study.

METHODS

Adult patients in a cardiac hospital who were in the postoperative period following cardiac surgery were included. Factors associated with the increased bleeding were investigated by means of linear regression, considering time intervals of 6 and 12 hr.

RESULTS

The sample comprised 391 participants. The factors associated with the increased bleeding in the first 6 hr were male sex, body mass index, cardiopulmonary bypass duration, anoxia duration, metabolic acidosis, higher heart rate, platelets and the activated partial thromboplastin time in the postoperative period. Predictors in the first 12 hr were body mass index, cardiopulmonary bypass duration, metabolic acidosis, higher heart rate, platelets and the activated partial thromboplastin time in the postoperative.

CONCLUSIONS

This study identified factors associated with the increased postoperative bleeding from cardiac surgery that have not been reported in previous studies. The nurse is important in the vigilance, evaluation and registry of chest tube drainage and modifiable factors associated with the increased bleeding, such as metabolic acidosis and postoperative heart rate, and in discussions with the multiprofessional team.

RELEVANCE TO CLINICAL PRACTICE

Knowledge of the factors associated with the increased bleeding is critical for nurses so they can provide prophylactic interventions and early postoperative treatment when needed.

Blood transfusion management in the severely bleeding military patient

PURPOSE OF REVIEW

Hemorrhage remains the primary cause of preventable death on the battlefield and in civilian trauma. Hemorrhage control is multifactorial and starts with point-of-injury care. Surgical hemorrhage control and time from injury to surgery is paramount; however, interventions in the prehospital environment and perioperative period affect outcomes. The purpose of this review is to understand concepts and strategies for successful management of the bleeding military patient. Understanding the life-threatening nature of coagulopathy of trauma and implementing strategies aimed at full spectrum hemorrhage management from point of injury to postoperative care will result in improved outcomes in patients with life-threatening bleeding.

RECENT FINDINGS

Timely and appropriate therapies impact survival. Blood product resuscitation for life-threatening hemorrhage should either be with whole blood or a component therapy strategy that recapitulates the functionality of whole blood. The US military has transfused over 10 000 units of whole blood since the beginning of the wars in Iraq and Afghanistan. The well recognized therapeutic benefits of whole blood have pushed this therapy far forward into prehospital care in both US and international military forces. Multiple hemostatic adjuncts are available that are likely beneficial to the bleeding military patient; and other products and techniques are under active investigation.

SUMMARY

Lessons learned in the treatment of combat casualties will likely continue to have positive impact and influence and the management of hemorrhage in the civilian trauma setting.

Short-term recovery pattern of plasma fibrinogen after cardiac surgery: A prospective observational study

Low plasma fibrinogen level is common after cardiopulmonary bypass (CPB). Current substitution practice with fibrinogen concentrate generally follows a single measurement and cut-off values from the literature, whereas early postoperative endogenous fibrinogen kinetics is incompletely described and widely disregarded. The aim of this study was to determine the short-term recovery pattern of plasma fibrinogen after CPB weaning. Our hypothesis was that in the absence of surgical bleeding, CPB-induced hypofibrinogenemia would resolve spontaneously and predictably within a few hours. In a prospective, observational study of 26 patients undergoing conventional CPB (cCPB) or minimally invasive extracorporeal circulation (MiECC), Clauss fibrinogen level (C-FIB) was determined at 10 closely spaced time points after protamine administration. Primary endpoint was the time to recovery of post-CPB fibrinogen levels to ≥1.5 g/L. C-FIB reached its nadir after protamine administration corresponding to 62 ± 5% (mean ± SD) of the baseline level after cCPB and 68 ± 7% after MiECC (p = 0.027 vs. cCPB). C-FIB recovered spontaneously at a nearly constant rate of approximately 0.08 g/L per hour. In all patients, C-FIB was ≥1.5 g/L at 4 hours and ≥2.0 g/L at 13 hours after CPB weaning. Following cardiac surgery with CPB and in the absence of surgical bleeding, spontaneous recovery of normal endogenous fibrinogen levels can be expected at a rate of 0.08 g/L per hour. Administration of fibrinogen concentrate triggered solely by a single-point measurement of low plasma fibrinogen some time after CPB is not justified.

Tabula viva chirurgic: a living surgical document

AIM

The purpose of this article is to present the results of a private cardiac surgical practice. This information could also serve as a hermeneutical text for new wisdom.

METHODS

A personal database of 1 750 consecutive patients who had had coronary artery bypass graft (CABG) surgery was statistically analysed. Mortality and major morbidity figures were compared with large registries. Risk factors for postoperative death were determined.

RESULTS

Over a period of 12 years, 1 344 (76.8%) males and 406 (23.2%) females were operated on. The observed mortality rate was 3.03% and the expected mortality rate (EuroSCORE) was 3.87%. After stepwise logistic regression, independent risk factors for death were urgency (intra-aortic balloon pump), renal impairment (chronic kidney disease, stage III), re-operation and an additional procedure. Apart from the 53 deaths, another 91 patients had major complications.

CONCLUSION

Mortality and morbidity rates compared favourably with other international registries. Mortality was related to co-morbidities. This outcome contributes to a hermeneutical understanding focusing on new spiritual wisdom and meaning for the surgeon.

Crotalus atrox venom preconditioning increases plasma fibrinogen and reduces perioperative hemorrhage in a rat model of surgical brain injury

Perioperative bleeding is a potentially devastating complication in neurosurgical patients, and plasma fibrinogen concentration has been identified as a potential modifiable risk factor for perioperative bleeding. The aim of this study was to evaluate preconditioning with Crotalus atrox venom (Cv-PC) as potential preventive therapy for reducing perioperative hemorrhage in the rodent model of surgical brain injury (SBI). C. atrox venom contains snake venom metalloproteinases that cleave fibrinogen into fibrin split products without inducing clotting. Separately, fibrinogen split products induce fibrinogen production, thereby elevating plasma fibrinogen levels. Thus, the hypothesis was that preconditioning with C. atrox venom will produce fibrinogen spilt products, thereby upregulating fibrinogen levels, ultimately improving perioperative hemostasis during SBI. We observed that Cv-PC SBI animals had significantly reduced intraoperative hemorrhage and postoperative hematoma volumes compared to those of vehicle preconditioned SBI animals. Cv-PC animals were also found to have higher levels of plasma fibrinogen at the time of surgery, with unchanged prothrombin time. Cv-PC studies with fractions of C. atrox venom suggest that snake venom metalloproteinases are largely responsible for the improved hemostasis by Cv-PC. Our findings indicate that Cv-PC increases plasma fibrinogen levels and may provide a promising therapy for reducing perioperative hemorrhage in elective surgeries.

Four-Group Classification Based on Fibrinogen Level and Fibrin Polymerization Associated With Postoperative Bleeding in Cardiac Surgery

Fibrinogen and fibrin formation have a key role in perioperative hemostasis. The aim of this study is to examine the association of postoperative hemostasis with a combined evaluation of the fibrinogen level and fibrin polymerization in cardiac surgery. We retrospectively classified 215 consecutive cardiac surgery patients into 4 groups (Fuji-san classification) that were divided by fibrinogen level <150 mg/dL (ie, hypofibrinogenemia) and fibrinogen thromboelastometry value at 10 minutes with rotational thromboelastometry <6 mm (ie, low fibrin polymerization) at the warming of cardiopulmonary bypass. Four groups resulted; group I, the acceptable range (n = 85); group II, only hypofibrinogenemia (<150 mg/dL, ≥6 mm, n = 63); group III, hypofibrinogenemia and low fibrin polymerization (<150 mg/dL, <6 mm, n = 60); and group IV, only low fibrin polymerization (≥150 mg/dL, <6 mm, n = 7). The risk of chest tube drainage volume greater than 500 mL within the first 24 hours after surgery (with group I as the reference) was increased in group II (odds ratio [OR], 3.3; 95% confidence interval [CI], 1.5-7.4; P < .01) and group III (OR, 8.5; 95% CI, 3.5-21.7; P < .01), and the risk greater than 1000 mL (with group I as the reference) was increased in group III (OR, 4.0; 95% CI, 1.1-17.3; P = .03) and group IV (OR, 23.1; 95% CI, 3.2-201.0; P < .01). Intraoperative blood transfusions were decreased by 24.5%, after stratifying the starting amount of fresh frozen plasma by the 4-group classification in the recent consecutive 65 (30.2%) patients ( P < .01). The 4-group classification is associated with postoperative bleeding and may improve the quality of perioperative blood transfusion in cardiac surgery.

Simultaneous measurement of thrombin generation and fibrin formation in whole blood under flow conditions

Assays based on the formation of thrombin and fibrin are frequently used, and results are considered exchangeable in research/clinical settings. However, thrombin generation and fibrin formation do not always go hand in hand and flow profoundly influences thrombus formation. We describe the technical/clinical evaluation of an assay to simultaneously measure thrombin generation and fibrin formation under conditions of flow. Introduction of a fluorometer into a 'cone and base principle'-based rheometer allowed the measurement of thrombin generation (using a thrombin-sensitive substrate) and fibrin formation (changes in viscosity), while applying a linear shear flow. Increasing shear rates inversely related with thrombin generation and fibrin formation. Increasing fibrinogen concentrations in defibrinated plasma resulted in increased thrombin generation and fibrin formation. In pre-operative samples of 70 patients undergoing cardiothoracic surgery, fibrin formation and thrombin generation parameters correlated with fibrinogen content, rotational thromboelastometry (ROTEM) and whole blood Calibrated Automated Thrombinography (CAT) parameters, respectively. Upon dividing patients into two groups based on the median clot strength, a significant difference in perioperative/total blood loss was established. In conclusion, we clinically evaluated a method capable of simultaneously measuring thrombin generation and fibrin formation in plasma/whole blood under continuous flow, rendering our method one step closer to physiology. Importantly, our test proved to be indicative for the amount of blood loss during/after cardiothoracic surgery.

Endocarditis is not an Independent Predictor of Blood Transfusion in Aortic Valve Replacement Patients With Severe Aortic Regurgitation

OBJECTIVE

This study sought to evaluate if the presence of endocarditis was independently associated with increased perioperative blood transfusion in patients undergoing aortic valve replacements (AVR) with aortic regurgitation.

DESIGN

This was a retrospective study.

SETTING

Large Canadian tertiary care hospital.

PARTICIPANTS

Six hundred sixty-two consecutive patients with aortic regurgitation score of 3 or higher undergoing AVR from 1995 to 2012.

INTERVENTIONS

No interventions were performed in this retrospective study.

MEASUREMENTS AND MAIN RESULTS

After REB approval, data were obtained from a center-specific database. Univariate analysis was performed to identify variables that may be associated with transfusion of any allogeneic blood product perioperatively. A multivariate logistic regression was generated to identify independent predictors of perioperative transfusion. Unadjusted transfusion rates in patients with no endocarditis and with endocarditis were 32% and 70% (p<0.001), respectively. Independent predictors of any transfusion were moderate-to-severe preoperative anemia, preoperative renal failure, non-isolated AVR, age>70, urgent/emergent surgery, BMI<25, and female sex. Endocarditis was not an independent predictor of transfusion (OR = 0.748; 95% CI = 0.35-1.601).

CONCLUSIONS

In patients undergoing AVR, unadjusted perioperative transfusion rates were higher when endocarditis was present. However, after adjustment, aortic valve endocarditis was not independently associated with blood transfusion. The authors' observation could be explained by the higher prevalence of many independent predictors of transfusion, such as comorbidities or more complex surgery, within the endocarditis group. Thus, AV endocarditis, in the absence of other risk factors, was not associated with increased perioperative transfusion risk.

Comparison of functional fibrinogen (FF/CFF) and FIBTEM in surgical patients – a retrospective study

Fibrinogen-based clot firmness is reported as the maximum amplitude (MA) when using the citrated functional fibrinogen (CFF) assay in thrombelastography (TEG), and as the maximum clot firmness (MCF) together with several clot amplitude parameters when using the FIBTEM assay in thromboelastometry (ROTEM). Concern is currently being raised that these two tests have different platelet inhibiting performance and consequently provide different values. This is relevant for the clinical setting of fibrinogen replacement. We aim herein to compare the parameters of these two fibrinogen-based clot quality tests and their correlation with the plasma fibrinogen level as determined by the Clauss method.

In total 261 whole blood samples taken from 163 clinical routine surgical patients were analyzed with TEG 5000 and ROTEM tests, and correlation with Clauss fibrinogen level was assessed.

: Using TEG, the overall fibrin-based clot firmness measured in the CFF assay was significantly higher than the MCF measured by FIBTEM assay. Both assays showed significantly positive correlations with the fibrinogen levels measured using the Clauss method. However, individual values of Clauss fibrinogen concentration corresponded with different values for the two viscoelastometric tests; e.g. within the range of 1.9–2.1 g/L Clauss fibrinogen the median of CFF MA was 16.3 mm whereas FIBTEM MCF was 12.0 mm.

: We showed herein by measurements of citrated whole blood samples from surgical patients that CFF MA values were different from FIBTEM MCF values measured in the same sample. Awareness that these whole blood assays provide different clot amplitude results is mandatory, particularly if they are being considered as tools for guiding fibrinogen supplementation. Thromboembolic side effects caused by a potentially too high fibrinogen substitution must also kept in mind in this context.