The effects of high-dose heparin on inflammatory and coagulation parameters following cardiopulmonary bypass

A Blinded Randomized Trial Comparing Standard Activated Clotting Time Heparin Management to High Target Active Clotting Time and Individualized Hepcon HMS Heparin Management in Cardiopulmonary Bypass Cardiac Surgical Patients

Purpose: High-dose heparin has been suggested to reduce consumption coagulopathy.

Materials and Methods: In a randomized, blinded, prospective trial of patients undergoing elective, complex cardiac surgery with cardiopulmonary bypass, patients were randomized to one of three groups: 1) high-dose heparin (HH) receiving an initial heparin dose of 450 u/kg, 2) heparin concentration monitoring (HC) with Hepcon Hemostasis Management System (HMS; Medtronic, Minneapolis, MN, USA) monitoring, or 3) a control group (C) receiving a standard heparin dose of 300 u/kg. Primary outcome measures were blood loss and transfusion requirements.

Results: There were 269 patients block randomized based on primary versus redo sternotomy to one of the three groups from August 2001 to August 2003. There was no difference in operative bleeding between the groups. Chest tube drainage did not differ between treatment groups at 8 hours (median [25th percentile, 75th percentile] for control group was 321 [211, 490] compared to 340 [210, 443] and 327 [250, 545], p = 0.998 and p = 0.540, for HH and HC treatment groups, respectively). The percentage of patients receiving transfusion was not different among the groups.

Conclusion: Higher heparin dosing accomplished by either activated clot time or HC monitoring did not reduce 24-hour intensive care unit blood loss or transfusion requirements.

Will high-dose heparin affect blood loss and inflammatory response in patients undergoing cardiopulmonary bypass?

INTRODUCTION

We performed a randomized study to investigate if a high versus a standard dose of heparin dose during cardiopulmonary bypass could affect intra- and post-operative bleeding and reduce the inflammatory response.

METHODS

A total of 30 patients undergoing elective coronary artery bypass grafting were randomized into high or standard dose of heparin during cardiopulmonary bypass. Blood loss was documented peri- and post-operatively, and interleukin-6, tumor necrosis factor-α, and C3 were measured in conjunction with cardiopulmonary bypass.

RESULTS

Data from 29 patients were analyzed after exclusion of one patient. The mean initial bolus and total heparin doses were 43,000 ± 5,800 IU versus 35,000 ± 4,100 IU, (p < 0.001), and 58,000 ± 9,500 IU versus 45,000 ± 7,900 IU, (p < 0.001) in the intervention and the control group, respectively. The median intra-operative bleeding was 150 mL (interquartile range 100-325) in the control versus 225 mL (IQR 200-350) in the intervention group, p = 0.15. The median chest tube blood loss 12 hour post-operatively was 300 mL (interquartile range 250-385) in the control versus 450 mL (IQR 315-505) in the intervention group, p = 0.029. There was no significant difference between the control group and the intervention group during cardiopulmonary bypass for the measured inflammatory markers interleukin-6 (p = 0.98), tumor necrosis factor-α (p = 0.72), or C3 (p = 0.13).

CONCLUSION

This small study showed a small increase of post-operative bleeding associated with higher heparin dosage in conjunction with cardiopulmonary bypass but did not demonstrate an effect of heparin on the inflammatory response to cardiopulmonary bypass.

Anti-Inflammatory Effects of Heparin and Its Derivatives: A Systematic Review

Background. Heparin, used clinically as an anticoagulant, also has anti-inflammatory properties. The purpose of this systematic review was to provide a comprehensive review regarding the efficacy and safety of heparin and its derivatives as anti-inflammatory agents. Methods. We searched the following databases up to March 2012: Pub Med, Scopus, Web of Science, Ovid, Elsevier, and Google Scholar using combination of Mesh terms. Randomized Clinical Trials (RCTs) and trials with quasi-experimental design in clinical setting published in English were included. Quality assessments of RCTs were performed using Jadad score and Consolidated Standards of Reporting Trials (CONSORT) checklist. Results. A total of 280 relevant studies were reviewed and 57 studies met the inclusion criteria. Among them 48 studies were RCTs. About 65% of articles had score of 3 and higher according to Jadad score. Twelve studies had a quality score > 40% according to CONSORT items. Asthma (n = 7), inflammatory bowel disease (n = 5), cardiopulmonary bypass (n = 8), and cataract surgery (n = 6) were the most studied disease condition. Forty studies use unfractionated heparin (UFH) for intervention; the remaining studies use low molecular weight heparin (LMWH). Conclusion. Despite the conflicting results, heparin seems to be a safe and effective anti-inflammatory agent; although it is shown that heparin can decrease the level of inflammatory biomarkers and improves patient conditions, still more data from larger rigorously designed studies are needed to support use of heparin as an anti-inflammatory agent in clinical setting. However, because of the association between inflammation, atherogenesis, thrombogenesis, and cell proliferation, heparin and related compounds with pleiotropic effects may have greater therapeutic efficacy than compounds acting against a single target.

Heparin toxicity in cell culture: a critical link in translation of basic science to clinical practice

Heparin is a universal drug used frequently for its anticoagulant effects. The variabilities in distribution and tendency of heparin to accumulate in tissues cause increased tissue concentrations despite normal serum levels. We aimed to underline the toxic effects of heparin in cell culture make projections for clinical applications. L929 mouse fibroblastic cell line was plated in 96-well culture plates at an initial density of 5000 cells/well. Heparin was prepared in 10 different concentrations (10-300 units/well). Following 3 days of incubation, viabilities were assessed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay for each concentration in each day and compared. The viability of cells decreased significantly with increasing doses of heparin; at least 50 units/well in the first and second days and at least 20 units/well in the third day (P < 0.05 for each). There was statistically significant difference when the viabilities of cells treated with same heparin concentration in different days were compared (P < 0.05). The authors clearly demonstrated the toxic effects of heparin in cell culture, toxic effects increased as the dose increased. To prevent the unwanted clinical side-effects of heparin further studies should be made and more accurate testing methods should be developed to determine the effective tissue concentration of heparin.

[Blood transfusion via the cardiopulmonary bypass circuit: the anesthesiologist point of view]

Cardiac surgery frequently requires blood transfusion. The use of transfusion should be restricted due to side effects. Blood transfusion via the cardiopulmonary bypass (CPB) circuit is easy and allows a fast transfusion. The administration of packed red cells is relatively frequent because of the CPB-induced hemodilution and of the higher rate of postoperative complications when the haematocrit during CPB decreases below 20%. This transfusion of packed red cells does not seem to be associated with complications during CPB. Platelet transfusion during bypass is illogical because of the destruction of platelets during CPB and must be avoided. Fresh frozen plasma transfusion during CPB is seldom indicated but is possible. It could reverse heparin resistance.

Restoration of neutrophil immunocompetence after cardiopulmonary bypass by beta-adrenergic blockers

BACKGROUND

To evaluate the possible protective effect of sympatholytic medications with respect to neutrophil function, we evaluated the influence of a nonselective beta-blocker medication on the interaction of neutrophils and epinephrine after cardiopulmonary bypass. Therefore, we studied the importance of adrenoceptors for the immunomodulation of neutrophils by catecholamines in vitro.

METHODS

First, we investigated the modulation of neutrophils from healthy volunteers, after stimulation with n-formyl-l-methionyl-l-leucyl-l-phenylalanin (FMLP) in the presence of epinephrine with or without the addition of one of the following adrenergic receptor antagonists: atenolol, butoxamine, pindolol, prazosin, or RS79984. The second part included an investigation of the modulation of neutrophils from patients after operative coronary revascularization with or without extracorporeal circulation after stimulation with FMLP and addition of epinephrine. After loading with anti-CD62l or anti-CD11b antibodies or dihydrorhodamine, the expression of CD62l and CD11b and generation of oxidative free radicals were assessed by flow cytometry.

RESULTS

The suppression of oxidative free radical generation, inhibition of CD62l downregulation after stimulation with FMLP, and suppression of CD11b upregulation after FMLP stimulation from epinephrine were all mediated by beta(2)-adrenoceptors. After cardiac surgery with cardiopulmonary bypass, epinephrine inhibited the CD62l downregulation, the suppression of CD11b upregulation, and the generation of oxidative free radicals after FMLP stimulation. The pre-operative administration of beta-blockers abolished the immunomodulatory effects of epinephrine on CD62l and CD11b expression and the generation of oxidative free radicals.

CONCLUSION

The immunomodulatory effects of epinephrine on neutrophils remained unchanged irrespective of cardiopulmonary bypass and could contribute to the detrimental effects of epinephrine after heart surgery. The preoperative administration of nonselective beta-blockers abolished the immunomodulatory effects of epinephrine in vitro and in patients, and it enhanced the immunocompetence of neutrophils in a context of increased catecholamine levels.

The impact of different biocompatible coated cardiopulmonary bypass circuits on inflammatory response and oxidative stress

This study was to compare the impact of different biocompatible coated circuits on inflammatory response and oxidative stress induced during cardiopulmonary bypass (CPB). Seventy-eight patients undergoing elective coronary artery bypass grafting (CABG) with CPB were randomly assigned to five groups with different biocompatible coated circuits: Trillium, Bioline, Phosphorylcholine, Polymethoxyethyl acrylate (PMEA), and the uncoated control group. Blood was drawn at three different time points: before CPB, 6 and 72 hours post CPB. Unlike the Trillium group, serum levels of TNF-α in the Bioline and Phosphorylcholine groups significantly increased only at 72 hours post CPB (p < 0.05). Serum levels of IL-6 significantly increased at 6 and 72 hours post CPB in all groups (p < 0.01). The Trillium group showed a significant increase of IL-10 compared to the control group at 72 hours post CPB (p < 0.05). Serum levels of NOx in the Phosphorylcholine group significantly decreased at 6 hours post CPB compared to baseline (p < 0.05). Both the Bioline and Phosphorylcholine groups showed statistical decreases in serum NOx levels compared with other groups at 6 hours post CPB (p < 0.05). A significant difference in NOx levels between the Bioline and the control group was also observed at 72 hours post CPB. Myeloperoxidase levels were significantly elevated at 6 and 72 hours post CPB in all groups (p < 0.05). Inflammatory response and oxidative stress are elevated during CABG with CPB. Heparin-coated and the Phosphorylcholine-coated circuits induce less inflammatory responses and oxidative stress compared to other circuits.

Release of cardiac biochemical and inflammatory markers in patients on cardiopulmonary bypass undergoing coronary artery bypass grafting

BACKGROUND

Determination of cardiac markers can assess cardiac injury induced by cardiopulmonary bypass (CPB) during coronary artery bypass grafting (CABG). However, the markers and their release pattern are not well defined. This study was aimed at assessing the release and timing of cardiac biochemical and inflammatory markers in patients undergoing elective CABG with CPB.

METHODS

Forty patients undergoing elective CABG were included in this study. Blood samples were collected for biochemical measurements at the following time points: immediately prior to the induction of anesthesia, one, six, 12, and 24 hours after initiation of CPB.

RESULTS

Increased release of cardiac troponin I was observed one hour after initiation of CPB (p < 0.05) and reached the maximum at 12 hours after CPB (p < 0.01). Serum CK-MB enzyme activity and CK-MB mass both were highly elevated starting at one hour after initiation of CPB, peaked at six hours, and remained elevated until 24 hours after CPB. Both lactate and lactate dehydrogenase were highly elevated six hours after CPB and peaked at 12 hours after CPB (p < 0.01). Serum levels of interleukin-6 and tumor necrosis factor-alpha increased significantly one hour after initiation of CPB and peaked at six hours (p < 0.01), while serum high sensitivity C-reactive protein levels started to elevate 12 hours after CPB (p < 0.01).

CONCLUSION

Monitoring of these markers could help to determine implementation of protective interventions during CABG with CPB to prevent myocardial deterioration and to predict the risk and prognosis.

The anti-inflammatory effects of heparin and related compounds

Heparin is a glycosaminoglycan well known for its anticoagulant properties. In addition, heparin possesses anti-inflammatory effects. Although the mechanisms responsible for the anticoagulant effects of heparin are well understood, those underlying its anti-inflammatory effects are not. This review presents some of the evidence from clinical and animal studies supporting an anti-inflammatory role for heparin and heparin-related derivatives. Potential mechanisms by which heparin can exert its anti-inflammatory effects are discussed. The clinical use of heparin as an anti-inflammatory agent has been held back by the fear of bleeding. Development of nonanticoagulant heparins or heparin derivatives should mitigate this concern.

Perioperative blood transfusion and blood conservation in cardiac surgery: the Society of Thoracic Surgeons and The Society of Cardiovascular Anesthesiologists clinical practice guideline

BACKGROUND

A minority of patients having cardiac procedures (15% to 20%) consume more than 80% of the blood products transfused at operation. Blood must be viewed as a scarce resource that carries risks and benefits. A careful review of available evidence can provide guidelines to allocate this valuable resource and improve patient outcomes.

METHODS

We reviewed all available published evidence related to blood conservation during cardiac operations, including randomized controlled trials, published observational information, and case reports. Conventional methods identified the level of evidence available for each of the blood conservation interventions. After considering the level of evidence, recommendations were made regarding each intervention using the American Heart Association/American College of Cardiology classification scheme.

RESULTS

Review of published reports identified a high-risk profile associated with increased postoperative blood transfusion. Six variables stand out as important indicators of risk: (1) advanced age, (2) low preoperative red blood cell volume (preoperative anemia or small body size), (3) preoperative antiplatelet or antithrombotic drugs, (4) reoperative or complex procedures, (5) emergency operations, and (6) noncardiac patient comorbidities. Careful review revealed preoperative and perioperative interventions that are likely to reduce bleeding and postoperative blood transfusion. Preoperative interventions that are likely to reduce blood transfusion include identification of high-risk patients who should receive all available preoperative and perioperative blood conservation interventions and limitation of antithrombotic drugs. Perioperative blood conservation interventions include use of antifibrinolytic drugs, selective use of off-pump coronary artery bypass graft surgery, routine use of a cell-saving device, and implementation of appropriate transfusion indications. An important intervention is application of a multimodality blood conservation program that is institution based, accepted by all health care providers, and that involves well thought out transfusion algorithms to guide transfusion decisions.

CONCLUSIONS

Based on available evidence, institution-specific protocols should screen for high-risk patients, as blood conservation interventions are likely to be most productive for this high-risk subset. Available evidence-based blood conservation techniques include (1) drugs that increase preoperative blood volume (eg, erythropoietin) or decrease postoperative bleeding (eg, antifibrinolytics), (2) devices that conserve blood (eg, intraoperative blood salvage and blood sparing interventions), (3) interventions that protect the patient's own blood from the stress of operation (eg, autologous predonation and normovolemic hemodilution), (4) consensus, institution-specific blood transfusion algorithms supplemented with point-of-care testing, and most importantly, (5) a multimodality approach to blood conservation combining all of the above.