Significance of D-dimer concentrations during and after cardiopulmonary bypass

A Pharmacokinetic and Pharmacodynamic Investigation of an ε-Aminocaproic Acid Regimen Designed for Cardiac Surgery With Cardiopulmonary Bypass

OBJECTIVE

To investigate the pharmacokinetics and pharmacodynamics of an ε-aminocaproic acid (EACA) regimen designed for cardiac surgery with cardiopulmonary bypass (CPB).

DESIGN

Prospective observational study requiring blood sampling to measure EACA concentrations and fibrinolysis markers (fibrinogen, D-dimer, α₂-antiplasmin, and tissue plasminogen activator-plasminogen activator inhibitor [tPA-PAI-1] complex).

SETTING

Single-center, tertiary medical center.

PARTICIPANTS

Patients who underwent cardiac surgery with CPB between 2018 and 2019 for aortic or mitral valve replacement/repair or coronary artery bypass grafting. Previous sternotomy patients were included.

INTERVENTION

None.

MEASUREMENTS AND MAIN RESULTS

The pharmacokinetics of EACA, during CPB, were described by a 3-compartment disposition model. EACA concentrations were greater than 130 mg/L in all patients after CPB and in most patients during CPB. The D-dimer level trended up and reached a peak median level of 1.35 mg/L of fibrinogen equivalence units (FEU) at 15 minutes after protamine administration. The median change in D-dimer (ΔD-dimer) from baseline to 15 minutes after protamine was 0.34 (-0.48 to 3.81) mg/L FEU. ΔD-dimer did not correlate with EACA concentration intraoperatively, urine output, body weight, glomerular filtration rate, cell salvage volume, and ultrafiltration volume. The median 24-hour chest tube output was 445 (180-1,011) mL.

CONCLUSION

This regimen provided maximum EACA concentrations near the time of protamine administration, with a total perioperative dose of 15 g. Most patients had EACA concentrations greater than the target during CPB. ΔD-dimer did not correlate with EACA concentration. The median 24-hour chest tube output compared well to similar studies that used higher doses of EACA.

Type II Minimal-Invasive Extracorporeal Circuit for Aortic Valve Replacement: A Randomized Controlled Trial

Extracorporeal circulation triggers systemic inflammatory response and coagulation disorders which may lead to unfavorable clinical outcome. A type II minimally-invasive extracorporeal circuit (MiECC) is a closed system with markedly reduced artificial surface as compared to conventional extracorporeal circuits (CECC). The aim of this study was to investigate and compare inflammatory responses, complement activation and selected clinical end-points in isolated surgical aortic valve replacement (SAVR) performed with a type II MiECC circuit or a CECC. Fifty patients were prospectively randomized to MiECC or CECC perfusion regimen. Complement activation (sC5b-9), inflammation (IL-6, TNF-α, sCD40-ligand) and activation of the coagulation system (D-dimer, TAT-complex) were determined before operation, at 2 hours and 24 hours after surgery. Clinical end-points included perfusion time, transfusion of allogeneic blood products, postoperative bleeding, sepsis, new onset of atrial fibrillation, stroke and in-hospital mortality. Patient characteristics and baseline plasma markers were similar in both groups. Levels for sC5b-9, TNF-α, sCD40 ligand, TAT-complex and D-dimers were not significantly different between MiECC and CECC at 2 hours and 24 hours after surgery. The IL-6 plasma concentration was lower in the CECC group at 24 hours (P = 0.026, vs. MiECC). Comparisons of the baseline level to values at 2 hours and 24 hours, adjusted for the type of oxygenator and hemoglobin, showed a significantly lower sC5b-9 in MiECC at 2 hours (P = 0.013), but no difference at 24 hours (P=0.990). Compared with CECC, MiECC patients had a shorter perfusion time (P = 0.037) and less transfusion requirements (P = 0.04). In this selected cohort of SAVR patients, the type II MiECC was not inferior to CECC in terms of inflammatory response and complement activation. Thus, MiECC might be an alternative perfusion strategy to conventional.

Prophylactic Fibrinogen Infusion in Cardiac Surgery Patients: Effects on Biomarkers of Coagulation, Fibrinolysis, and Platelet Function

Objective: We have recently reported that prophylactic fibrinogen infusion reduces bleeding after coronary artery bypass grafting (CABG) surgery. Because fibrinogen for the first time was administered to patients without hereditary fibrinogen deficiency or ongoing bleeding, a detailed analysis of the effects of fibrinogen concentrate on biomarkers of coagulation, fibrinolysis, and platelet function was performed. Methods: Twenty CABG patients with preoperative plasma fibrinogen levels <3.8 g/L were included in a prospective study. Patients were randomized to preoperative infusion of 2 g fibrinogen concentrate (fibrinogen group) or no infusion (control group). Activated partial thromboplastin time (aPTT), prothrombin time, activated clotting time, and plasma concentrations of fibrinogen, antithrombin, thrombin-antithrombin complex, prothrombin fragment 1.2, and D-dimer, thromboelastometry, platelet count, and platelet aggregometry were analyzed before and 15 minutes after infusion, and 2 and 24 hours after surgery. Results: Fifteen minutes after infusion of fibrinogen concentrate, fibrinogen plasma levels increased by 0.6 ± 0.2 g/L (P < .001 between groups), and induced minimal changes in aPTT and plasma levels of antithrombin, while remaining variables remained unchanged. After surgery, fibrinogen levels no longer differed between groups. D-dimer was significantly higher after surgery in the fibrinogen group (P = .03), while none of the other markers were statistically different between groups. Conclusions: Infusion of 2 g fibrinogen to cardiac surgery patients, without hereditary or acquired fibrinogen deficiency or ongoing bleeding, results in no or minimal changes in biomarkers reflecting coagulation and platelet function. An increased release of fibrin degradation products was detected after surgery in fibrinogen-treated patients.

Heparin reduction with the use of cardiotomy suction is associated with hyperfibrinolysis during distal aortic perfusion with a heparin-coated semi-closed cardiopulmonary bypass system

We sought to elucidate the effects of different anticoagulation levels and the use of cardiotomy suction on the postoperative coagulatory and fibrinolytic systems in patients undergoing distal aortic perfusion using a fully heparin-coated (semi-)closed cardiopulmonary bypass (CPB) system incorporating a soft reservoir bag. Thirty-two patients were divided into two groups: those who underwent cardiotomy suction (S group, 18 patients) and those who did not (N group, 14 patients). We administered 1-2 mg/kg heparin in the S group, which achieved an activated clotting time (ACT) of 345 +/- 71 s. In the N group, we administered 0.7-1 mg/kg heparin, which achieved an ACT of 297 +/- 52 s. Data on platelet counts and serum levels of fibrinogen, antithrombin III, D-dimer, and fibrin degradation products (FDP) were collected, and factors influencing these variables were analyzed by multiple regression analysis. Both the patient group and the initial ACT level were independent factors influencing postoperative levels of FDP and D-dimer, whereas peak ACT level and the use of selective visceral/renal shunt/perfusion, but not the patient group, were independent factors influencing the postoperative platelet counts. In the S group, a significant inverse correlation was found between the ACT and levels of FDP or D-dimer, whereas no correlation was found in the N group. The use of cardiotomy suction was associated with elevated FDP and D-dimer levels even when a fully heparin-coated semi-closed CPB system was used. Lower ACT levels with the use of cardiotomy suction were associated with higher FDP and D-dimer levels, whereas such a relationship did not exist when cardiotomy suction was not used.

Monitoring of fibrinolysis parameters during myocardial revascularization according to type of procedure

The aim of the study was to assess the effect of cardiothoracic surgery on the dynamics of plasminogen, D-dimers and plasminogen activator inhibitor (PAI-I) during the first 24h after surgery. The study included 14 patients operated with (on-pump) and 14 without (off-pump) the use of extracorporeal circulation (ECC). Blood sampling was carried out on induction of anesthesia (timepoint 1), on introduction of heparin (point 2) and protamine (point 3), at the end of surgery (point 4), and the next morning (point 5). Relative to point 1, the utilization of plasminogen at point 2 was 24% and 17% in the on-pump and off-pump groups, respectively (p=0.001 both). Increased D-dimer concentration from the baseline was more pronounced in the on-pump group (p=0.001). At point 5, D-dimer concentrations were comparable in both groups and different from baseline levels. PAI-I activity showed within-group differences from baseline at point 5 in the off-pump group (p=0.001), and at points 3 and 5 in the on-pump group (p=0.002 and 0.001, respectively). At point 5, the activity of PAI-I was comparable in both groups, yielding p=0.001 vs. baseline. Fibrinolysis was more pronounced and more dynamic in the on-pump group due to activation of the systemic inflammatory response induced by the use of ECC. In the off-pump group, fibrinolysis was a normal physiological response to the surgical procedure.

d-Dimer as marker for microcirculatory failure: correlation with LOD and APACHE II scores

The relevance of plasma d-dimer levels as marker for morbidity and organ dysfunction in severely ill patients is largely unknown. In a prospective study we determined d-dimer plasma levels of 800 unselected patients at admission to our intensive care unit. In 91% of the patients' samples d-dimer levels were elevated, in some patients up to several hundredfold as compared to normal values. The highest mean d-dimer values were present in the patient group with thromboembolic diseases, and particularly in non-survivors of pulmonary embolism. In patients with circulatory impairment (r=0.794) and in patients with infections (r=0.487) a statistically significant correlation was present between d-dimer levels and the APACHE II score (P<0.001). The logistic organ dysfunction score (LOD, P<0.001) correlated with d-dimer levels only in patients with circulatory impairment (r=0.474). On the contrary, patients without circulatory impairment demonstrated no correlation of d-dimer levels to the APACHE II or LOD score. Taking all patients together, no correlations of d-dimer levels with single organ failure or with indicators of infection could be detected. In conclusion, d-dimer plasma levels strongly correlated with the severity of the disease and organ dysfunction in patients with circulatory impairment or infections suggesting that elevated d-dimer levels may reflect the extent of microcirculatory failure. Thus, a therapeutic strategy to improve the microcirculation in such patients may be monitored using d-dimer plasma levels.

Coagulation and fibrinolytic markers in a two-month follow-up of coronary bypass surgery

OBJECTIVES

The alterations of the coagulation-fibrinolytic profile immediately and up to few days after cardiac surgery have been widely documented. However, less information is available on whether these alterations persist for prolonged periods of time after the operation. In this study we have evaluated the coagulation-fibrinolytic profile of patients who underwent coronary artery surgery with cardiopulmonary bypass during a 2-month follow-up period.

METHODS

Twenty-six patients (age range, 50-75 years) were studied. Blood samples were collected before the intervention and at different time points postoperatively up to 2 months after the operation. Measurement of selected coagulation-fibrinolytic variables was carried out in plasma from 16 patients. Evaluation of tissue factor activity determined as procoagulant activity was performed in peripheral blood mononuclear leukocytes obtained from 10 patients.

RESULTS

Antigenic levels of clottable fibrinogen, prothrombin fragment F1.2, D-dimer, and thrombin-antithrombin complex were significantly increased during the first week after the intervention compared with preoperative values. Prothrombin fragment F1.2 levels returned to normal within 15 days, fibrinogen levels normalized within 30 days, and thrombin-antithrombin complex levels normalized at 45 days, whereas D-dimer values were still significantly higher 60 days postoperatively respective to baseline values. There was a trend toward an increased procoagulant activity from peripheral blood mononuclear leukocytes 4 days after the operation, whereas no changes of factor VII measured either as antigen or in its coagulant and activated forms were recorded throughout the study.

CONCLUSIONS

A marked activation of the coagulation-fibrinolytic system occurs after cardiopulmonary bypass and lasts for at least 2 months thereafter. This finding suggests that these alterations might account for the increased thrombotic risk of these patients during the postoperative period.

Tranexamic acid in off-pump coronary surgery: a preliminary, randomized, double-blind, placebo-controlled study

BACKGROUND

We evaluated the hemostatic effects of tranexamic acid, a synthetic antifibrinolytic drug, in patients undergoing beating-heart coronary surgery.

METHODS

Forty consecutive patients were in a double-blind manner, prospectively randomized into two groups: 20 patients received tranexamic acid (bolus of 1 g before skin incision, followed by continuous infusion of 400 mg/hr during surgery), and 20 patients received saline. As primary outcomes, bleeding and allogeneic transfusions were considered. D-dimer and fibrinogen plasma levels were also evaluated to monitor the activation of fibrinolysis. Major postoperative thrombotic events, as a potential consequence of antifibrinolytic treatment, were recorded.

RESULTS

The treatment group had significantly lower postoperative bleeding (median [25th to 75th percentiles]: 400 mL [337 to 490 mL] vs 650 ml [550 to 862 mL], p < 0.0001), lower need for allogeneic blood products (1,200 vs 5,300 mL, p < 0.001), and lower postoperative D-dimer plasma levels. No postoperative thrombotic complications were observed in either group.

CONCLUSIONS

In this initial series of patients undergoing off-pump coronary surgery, tranexamic acid appears to be effective in reducing postoperative bleeding and the need for allogeneic blood products.

Comparison of hypotensive epidural anaesthesia and spinal anaesthesia on blood loss and coagulation during and after total hip arthroplasty

BACKGROUND

Hypotensive epidural anaesthesia (HEA) is a technique for reducing peroperative blood loss by significantly lowering mean arterial pressure (MAP).

METHODS

Thirty patients scheduled for primary total hip arthroplasty were given HEA (n=15) or spinal anaesthesia (SPA) (n= 15) with bupivacaine in random order. The dose of bupivacaine was titrated to provide epidural blockade up to T1-T4 and spinal blockade at least to T10. Intravenous adrenaline infusion was adjusted to achieve a MAP of about 50-60 mmHg in the HEA group. During SPA MAP was maintained above 70 mmHg with ephedrine, as needed.

RESULTS

Intraoperative blood loss (median and 25th and 75th percentiles) was 400 ml (163-575) in the HEA group and 900 ml (663-1,100) in the SPA group (P<0.05). At 3 h postoperatively cumulative blood loss was still smaller in the HEA group (600 ml versus 1,100 ml, P<0.05). The cumulative number of transfused packed red cell concentrate (PRC) units was smaller in the HEA group than in the SPA group during surgery and postoperatively. Prothrombin time value was smaller in the SPA than in the HEA group (69% versus 79%, P<0.05) at 3 h postoperatively. D-dimer concentrations increased more in the SPA group at the end of the surgery and 3 h postoperatively (P<0.05).

CONCLUSIONS

HEA resulted in reduced blood loss due to hypotension and reduced number of transfused PRC units during total hip arthroplasty. Based on lower prothrombin time value and higher D-dimer concentrations in the SPA group, the coagulation system might be better preserved during HEA than SPA.

D-Dimer formation during cardiac and noncardiac thoracic surgery

The ability to make therapeutic decisions regarding excessive fibrinolysis in the perioperative period is limited by the lack of availability of a near site monitor of fibrinolysis. We investigated the use of a latex agglutination D-dimer assay to detect perioperative fibrinolysis in patients undergoing thoracic surgery with and without extracorporeal circulation. We studied 27 patients who underwent thoracic surgery requiring cardiopulmonary bypass (CPB; coronary artery bypass grafting, n = 12; valvular surgery, n = 15) and a cohort of 20 patients who underwent noncardiac thoracic surgical procedures not requiring CPB. The purpose of this investigation was to determine the relationship among alterations in the latex agglutination D-dimer assay, use of extracorporeal circulation, type of cardiac surgical procedure, and mediastinal and/or chest tube drainage (cardiac surgery only) in patients undergoing thoracic surgery. Perioperative D-dimer levels, measured by latex agglutination, had significant (P < or = 0.05) intragroup changes among patients undergoing cardiac surgery (requiring CPB) and the cohort of patients who underwent noncardiac thoracic surgery without CPB. Although intraoperative D-dimer levels were not increased in patients undergoing noncardiac thoracic surgery, postoperative levels were significantly (P < 0.05) increased (compared with preinduction). In cardiac surgery patients requiring CPB, intraoperative D-dimer formation was significantly (P < or = 0.05) increased but did not demonstrate any intragroup (coronary artery bypass grafting versus valvular surgery) differences. Finally, D-dimer levels were not associated with postoperative mediastinal and/or chest tube accumulative drainage measured at intervals up to 48 h postoperatively in patients undergoing cardiac surgery requiring CPB. Our study indicates that the latex agglutination D-dimer assay can detect excessive fibrinolysis perioperatively, and that extracorporeal circulation can significantly influence the pattern of D-dimer formation in patients undergoing thoracic surgery.

IMPLICATIONS

We assessed the ability of a readily available D-dimer assay to detect excessive fibrinolysis in patients undergoing thoracic surgery with and without extracorporeal circulation. The findings demonstrate that the assay used in this investigation reflected variable amounts of fibrinolysis in patients undergoing both types of thoracic surgery.

Fibrinolysis in pediatric patients undergoing cardiopulmonary bypass

OBJECTIVE

Thromboelastographic evaluation of the influence of fibrinolysis on blood loss and blood product transfusions in children during cardiac surgery.

DESIGN

Prospective study.

SETTING

University-affiliated, pediatric medical center.

PARTICIPANTS

Two hundred seventy-eight consecutive children undergoing cardiac surgery.

INTERVENTIONS

Blood sampling for coagulation tests, including native and protamine-modified thromboelastography.

MEASUREMENTS AND MAIN RESULTS

Blood coagulation tests were measured before, during, and after cardiopulmonary bypass (CPB). Demographic data, perioperative blood loss, and blood product transfusions were prospectively recorded. Fibrinolysis was defined as thromboelastography of A30/MA less than 0.85 (MA, maximum amplitude; A30, amplitude 30 minutes after MA) and was noted in 3% of children pre-CPB, 16% during CPB, and 3% post-CPB. Fibrinolysis before CPB was associated with poor cardiac output. Fibrinolysis during CPB occurred in young children (aged 350 +/- 836 days) undergoing complex surgery with prolonged CPB (119 +/- 48.8 minutes) and deep hypothermia (25.6 degrees C +/- 4.7 degrees C). These patients received blood products after CPB and were not fibrinolytic after transfusion. They incurred similar blood loss (in mL/kg) and received similar volumes of blood products (mL/kg) as age-matched and surgery-matched patients without fibrinolysis.

CONCLUSION

A group of children at risk for fibrinolysis during CPB was identified. However, fibrinolysis during CPB did not influence blood loss or the total volume of blood products transfused.