Autotransfusion in coronary artery bypass grafting: disparity in laboratory tests and clinical performance

Major Factors of Homologous Blood Transfusion in Valvular Heart Operation with Intraoperative Autologous Blood Predonation in Cases with Difficulty in Preoperative Predonation

Intraoperative autologous blood predonation is reported to be useful for the prevention of homologous blood transfusion in cardiac operations, especially in on-pump coronary artery bypass grafting (CABG). However, CABG is now performed more often off-pump than on-pump. We analyzed the major factors of homologous blood transfusion in 25 consecutive cases of valvular heart operation with intraoperative autologous blood predonation except those with preoperative autologous blood donation. Homologous blood was not transfused in 18 cases, but was in 7 cases only after cardiopulmonary bypass (CPB). The homologous transfusion was not correlated with body weight, CPB dilution or duration, or preoperative hematocrit level, but was found to correlate with age (R2=0.289, p=0.0413), bleeding output (R2=0.197, p=0.0485), and predonation blood volume (R2=0.436, p=0.0152). In conclusion, suitable intraoperative predonation may reduce the necessity for homologous blood transfusion in valvular heart operations.

Cell saver processing mitigates the negative effects of wound blood on platelet function

BACKGROUND

Wound blood is highly activated and has poor haemostatic properties. Recent data suggest that retransfusion of unwashed wound blood may impair haemostasis. We hypothesized that cell saver processing of wound blood before retransfusion reduces the negative effects.

METHODS

Wound blood was collected from 16 cardiac surgery patients during cardiopulmonary bypass. One portion of the wound blood was processed in a cell saver and one portion left unprocessed. Increasing amounts of unprocessed blood (10% and 20% of the systemic blood volume) or corresponding volumes of processed blood were added ex vivo to whole blood samples from the same patient. Clot formation was assessed by modified thromboelastometry (ROTEM(®) ) and platelet function with impedance aggregometry (Multiplate(®) ).

RESULTS

Addition of unprocessed wound blood significantly impaired clot formation and platelet aggregability. Cell saver processing before addition did not influence clot formation but abolished completely the negative effects of wound blood on platelet aggregability tested with all agonists. Median adenosine diphosphate-induced platelet aggregation was 51 (25th and 75th percentiles 42-69) when 20% processed cardiotomy suction blood was added vs. 34 (24-52) U when 20% unprocessed blood was added, P < 0.001. The corresponding figures for arachidonic acid-, thrombin receptor activating peptide- and collagen-induced aggregation was 21 (17-51) vs. 13 (10-25) U, 112 (87-128) vs. 78 (65-103) U and 58 (50-73) vs. 33 (28-44) U, respectively, all P < 0.001).

CONCLUSION

The results suggest that cell saver processing before retransfusion mitigates the negative effects of wound blood on platelet function despite that cell saver processing reduces platelet count.

Effects of two differently heparin-coated extracorporeal circuits on markers for brain and myocardial dysfunction

Objective: The two most commonly used heparin-coated systems for cardiopulmonary bypass (CPB) are the Carmeda Bio-Active Surface (CBAS) (Medtronic, Minneapolis, MN, USA) and the Duraflo II coating (Baxter Healthcare, Irvine, CA, USA). The two surfaces are technically unequal and previous experimental studies have demonstrated disparities in effects on the immune system and blood cells. However, little is known concerning the influence of the two surfaces on markers for brain and myocardial dysfunction.

Methods: Forty patients undergoing elective, primary coronary bypass grafting with CPB were prospectively randomized to either the CBAS system or the Duraflo II circuit. During and after CPB, biological markers for brain dysfunction and myocardial injury were analysed.

Results: Both markers for brain dysfunction S-100B and neuron-specific enolase (NSE) increased significantly during CPB ( p =0.01). The elevation during bypass correlated significantly with the duration of CPB ( r = 0.39 and r= 0.38, respectively, both p< 0.02). NSE was somewhat more elevated in the Duraflo II group at the end of CPB ( p =0.01) and 5 h after CPB ( p= 0.02); for S-100B, there were no intergroup differences. Also, the markers related to myocardial injury, myoglobin and creatine kinase (CK-MB) mass increased during CPB ( p= 0.01), while elevation of troponin-I occurred 5 h after CPB ( p= 0.01). There were no statistically significant intergroup differences. No significant correlation was seen between the release of cardiac markers and the duration of CPB. The clinical course was similar in both groups.

Conclusions: Except for a slightly higher elevation of NSE at the end of CPB and 5 h after CPB in the Duraflo II group, there were no significant differences between the CBAS group and the Duraflo II group concerning markers for brain and myocardial dysfunction.

Leukocyte removal efficiency of cell-washed and unwashed whole blood: an in vitro study

Leukocyte filtration of the cardiopulmonary bypass (CPB) perfusate after cardiac surgery has evolved as an important technique to prevent effector functions mediated by activated leukocytes. However, little is known about the filtration efficiency. Therefore, an in vitro study was conducted to define the leukocyte removal rate of a transfusion leukocyte-depletion filter, using cell-washed and unwashed whole porcine blood. In addition, the influence of different cell-washing protocols on the elimination rate of blood cells (leukocytes and platelets) was investigated.

Fresh, diluted, pooled, heparinized, porcine blood was processed using either a high-flow (HF, n-5) or quality-wash (QW, n-5) protocol on a continuous auto-transfusion system, or was left unprocessed (control n-5). Thereafter, all samples were filtered using a transfusion leukocyte-depletion filter. Blood samples for measurement of hematocrit, white blood cell count, including leukocyte differentiation and platelet count, were taken before and after filtration. To compare the experimental groups, the removal rate was presented as the fraction of leukocytes or platelets removed per plasma volume.

Cell washing significantly altered the fraction of leukocytes removed per plasma volume when compared to unprocessed blood (2.07 and 2.36 in the HF and QW groups, respectively, versus 1.34 in the control group, p-0.008 for both). No statistically significant difference in leukocyte removal rate was observed between the different cell-washing protocols. The leukocyte differential count showed that, during all experiments, the neutrophils were removed most efficiently (99.7%). Overall, significantly more platelets were depleted after cell washing compared to the control group (1.47 and 1.60 in the HF and QW groups, respectively, versus 1.12 in the control group, p-0.008 and 0.032, respectively). Furthermore, the amount of blood that could be filtered using a single pass technique did not significantly differ between the experimental groups. However, a larger variation in the total amount of filtered blood was observed in the unprocessed group (5709/398 mL) compared to the cell-washed groups (3609/42 and 4309/97 mL in the HF and QW groups, respectively).

In conclusion, blood processing with an auto-transfusion system significantly enhances the leukocyte and platelet removal efficiency of the transfusion leukocyte-depletion filter that was studied. In particular, neutrophils were efficiently removed.

The effects on coagulation of the reinfusion of unprocessed residual blood from the cardiopulmonary bypass

Background

Autologous blood transfusion is a common technique in cardiac surgery to directly re-infuse residual blood from the cardiopulmonary bypass (CPB) circuit to the patient. The objective of this study was to evaluate the effects of reinfusion of unprocessed residual pump blood on the coagulation system after separation from the CPB circuit and reversal of systemic heparin with protamine.

Measurements and main results

After ethics approval, 40 participants undergoing cardiac surgery were recruited in a prospective single center cohort study. Changes in coagulation were assessed with standard plasma based laboratory assays and thromboelastography. After the reinfusion of unprocessed residual pump blood there were decreases in the mean aPTT (effect size 6 s; SD: 6.05; p < 0.0001) and thrombin time (effect size 4.08 s; SD: 9.7; p = 0.01). There were no significant changes in PT, INR and D-dimer. Post reinfusion there were increases in fibrinogen, hemoglobin and platelet counts. There were improvements in the R-time (effect size 9.1 s; SD: 16.9; p = 0.0023), K-time (effect size 1.5 s; SD: 3.6 s; p = 0.0017), alpha angle (6.9°; SD: 15.8; p = 0.012), and maximum amplitude (3.0 mm; SD: 5.6, p = 0.002) on thromboelastography.

Conclusion

The reinfusion of unprocessed residual CPB blood resulted in no deleterious effects on the coagulation system measured by both the common laboratory plasma based measurements of coagulation and thromboelastography.

Activation of Coagulation and Fibrinolysis after Off-Pump Coronary Artery Bypass Grafting with or without Endotracheal General Anesthesia

Objective

In this study, we measured the activity of coagulation and fibrinolysis and clarified the presence of certain differences between off-pump coronary artery bypass grafting (OPCAB) cases and awake off-pump coronary artery bypass grafting (AOCAB) cases to evaluate whether AOCAB is actually safe from the viewpoint of coagulability.

Methods

8 underwent OPCAB and 6 underwent AOCAB. The following factors inducing coagulation and fibrinolysis were measured for upto 5 days after the operation: platelet counts, prothrombin time, activated partial thromboplastin time, fibrinogen, fibrin degeneration products, D-dimer, thrombin-antithrombin III complex (TAT), α2-plasmin inhibitor-plasmin complex, prothrombin fragment 1, 2 (F1+2), thrombomodulin, β-thromboglobulin (β-TG), and platelet factor-4.

Results

At 5 days after the operation, fibrin degeneration products, D-dimer, α2–plasmin inhibitor-plasmin complex, and F1 + 2 levels of the OPCAB group were significantly higher compared with their baseline values and those of the AOCAB group. At 5 days after the operation, thrombin-antithrombin III complex levels of the OPCAB group were significantly higher than those of the AOCAB group. Fibrinogen levels of the OPCAB group were significantly higher than their baseline values at 3 days after the operation (POD3) and 5 days after the operation (POD5).

Conclusions

In this study, the hypercoagulable state at POD5 was suggested in the patients in the OPCAB group, but not in those in the AOCAB group. Further study is necessary to confirm these results, and future studies would evaluate the potential benefit of AOCAB procedure from the viewpoint of perioperative coagulability.

Dealing with pericardial suction blood and residual pump volume: a review of current practices in the UK

The pathological effects of pericardial suction blood (PSB) have been well described in numerous studies for many years; yet, despite this, there is no definitive answer to the question of how best to attenuate this pathology. More recently, large studies have shown that, whilst PSB contains many factors indicating its pathological potential, the direct re-infusion of PSB and residual pump volume (RPV) after cardiopulmonary bypass (CPB) potentially reduces the risk of transfusion and is no more harmful to the patient than the re-infusion of cell salvage-processed PSB after CPB.We conducted a telephone audit of UK perfusion units to determine if current protocols and practices reflected this.We found that there is a definite majority processing RPV with cell-saving devices, with many units defining their protocols as "surgeon dependent" whilst half immediately returned PSB to the systemic circulation whilst on CPB. The results of this national audit suggest that the issue of dealing with PSB and RPV is confused, heavily influenced by surgical and anaesthetic preference and lacking clear guidance and high quality evidence.

Coronary artery surgery: cardiotomy suction or cell salvage?

Coronary artery bypass grafting (CABG) today results in what may be regarded as acceptable levels of blood loss with many institutions avoiding allogeneic red cell transfusion in over 60% of their patients. The majority of cardiac surgeons employ cardiotomy suction to preserve autologous blood during on-pump coronary artery bypass surgery; however the use of cardiotomy suction is associated with a more pronounced systemic inflammatory response and a resulting coagulopathy as well as exacerbating the microembolic load. This leads to a tendency to increased blood loss, transfusion requirement and organ dysfunction. Conversely, the avoidance of cardiotomy suction in coronary artery bypass surgery is not associated with an increased transfusion requirement. There is therefore no indication for the routine use of cardiotomy suction in on-pump coronary artery surgery.

Hemodynamic effects of cardiotomy suction blood

OBJECTIVE

Cardiac surgery induces a systemic inflammatory activation, which in severe cases is associated with peripheral vasodilation and hypotension. Cardiotomy suction blood contains high levels of inflammatory mediators, but the effect of cardiotomy suction blood on the vasculture is unknown. We investigated the effect of cardiotomy suction blood on systemic vascular resistance in vivo and whether cell-saver processing of suction blood affects the vascular response.

METHODS

Twenty-five patients undergoing coronary surgery (mean age, 68 +/- 2 years; 80% men) were included in a prospective randomized study. The patients were randomized to retransfusion of cell-saver processed (n = 13) or cell-saver unprocessed (n = 12) suction blood during full cardiopulmonary bypass. Mean arterial blood pressure was continuously registered during retransfusion, and systemic vascular resistance was calculated. Plasma concentrations of tumor necrosis factor alpha, interleukin 6, and complement factor C3a were measured in suction blood.

RESULTS

Retransfusion of cardiotomy suction blood induced a transient reduction in systemic vascular resistance in all patients. The peak reduction was significantly less pronounced in the group receiving cell-saver processed blood (-12% +/- 2% vs -28% +/- 3%, P = .001). There was a significant correlation between tumor necrosis factor alpha concentration in retransfused cardiotomy suction blood and peak reduction of systemic vascular resistance (r = 0.60, P = .002).

CONCLUSIONS

The results suggest cardiotomy suction blood is vasoactive and might influence vascular resistance and blood pressure during cardiac surgery. The observed vasodilation is proportional to the inflammatory activation of suction blood and can be reduced by processing suction blood with a cell-saving device before retransfusion.

Composition of the blood sampled from surgical drainage after joint arthroplasty: quality of return

BACKGROUND

The quality of blood obtained with a device for postoperative blood drainage and autotransfusion (Bellovac-ABT, Astra Tech AB) was investigated in 50 patients who underwent total hip replacement (THR) or total knee replacement (TKR) surgeries.

STUDY DESIGN AND METHODS

The Bellovac-ABT drainage set was inserted and blood collection began after skin closure (THR) or 15 minutes after tourniquet deflation (TKR). A collecting bag stayed in place for less than 6 hours. The product was then returned after sedimentation and discard of supernatant, without anticoagulants.

RESULTS

Blood returned with the Bellovac-ABT had optimal hemoglobin levels and red blood cell (RBC) counts; the low platelet count reduced the risk of disseminated intravascular coagulation. Inertia of materials maintained acceptable values of C-reactive protein, whereas cytokines and complement split products rose rapidly. Higher concentrations of adenosine triphosphate and 2,3-diphosphoglycerate than in circulating blood suggested a normal RBC metabolism. No adverse reactions were observed in any participants.

CONCLUSION

Because of its simplicity and safety, the Bellovac-ABT autologous blood transfusion system is recommended in THR or TKR without joint infection or malignancy.

Clinical efficacy of postoperative autologous transfusion of filtered shed blood in hip and knee arthroplasty

BACKGROUND

Total knee arthroplasty (TKA) or total hip arthroplasty (THA) regularly results in postoperative requirement of blood transfusion. Because of the disadvantages of allogeneic blood transfusion (ABT) such as the risk of transfusion-associated infections, incompatibility-related transfusion fatalities, or immunomodulatory effects, a continuing effort to reduce allogeneic blood transfusion is important. For this purpose, the effect of reinfusion of drain blood, via a postoperative wound drainage and reinfusion system, on the need for allogeneic blood transfusion was evaluated.

STUDY DESIGN AND METHODS

Using a prospective observational quality assessment design, we compared 135 patients scheduled for TKA or THA with a historic group of 96 patients. In the study group the Bellovac ABT autotransfusion system was used. The shed blood was returned either when 500 mL were collected or at most 6 hours after surgery. Compared were the preoperative, postoperative, and discharge hemoglobin, as well as the number of allogeneic blood transfusions.

RESULTS

There were no statistical differences between preoperative, postoperative, and discharge hemoglobin levels. Autologous transfusion reduced the number of patients receiving ABT overall from 35 percent (control) to 22 percent (study). The decrease of allogeneic transfusion requirement was most significant after TKA: from 18 percent to 6 percent (p < 0.001).

CONCLUSION

We conclude that the Bellovac ABT device reduces allogeneic blood transfusions in TKA and THA.

Coronary surgery without cardiotomy suction and autotransfusion reduces the postoperative systemic inflammatory response

BACKGROUND

Cardiotomy suction and autotransfusion of mediastinal shed blood may contribute to the inflammatory response after cardiac surgery. We compared inflammatory activation, myocardial injury, bleeding, and hemoglobin levels in patients undergoing coronary surgery with or without retransfusion of cardiotomy suction blood and mediastinal shed blood.

METHODS

Twenty-nine patients were included in a prospective randomized study. Cardiotomy suction blood and mediastinal shed blood were either retransfused or discarded. Plasma concentrations of the cytokines tumor necrosis factor-alpha and interleukin-6 and complement factor C3a were measured preoperatively and 10 minutes, 2 hours, and 24 hours after cardiopulmonary bypass. C-reactive protein, erythrocyte sedimentation rate, troponin-T, and hemoglobin levels were analyzed preoperatively, and 24 and 48 hours after cardiopulmonary bypass. Postoperative bleeding the first 12 hours was registered.

RESULTS

Baseline data did not differ between the groups. Plasma concentrations of tumor necrosis factor-alpha, interleukin-6, and C3a increased after surgery in both groups but significantly less in the group without cardiotomy suction and autotransfusion. The peak delta values in the no-retransfusion group was 36% (tumor necrosis factor-alpha), 47% (interleukin-6), and 75% (C3a) of the values in the retransfusion group. C-reactive protein, erythrocyte sedimentation rate, and troponin-T increased after surgery in both groups without intergroup differences. Postoperative bleeding and hemoglobin levels did not differ between the groups. No patient received homologous blood transfusion.

CONCLUSIONS

Coronary surgery without retransfusion of cardiotomy suction blood and mediastinal shed blood reduces the postoperative systemic inflammatory response.

Quality of intraoperative autologous blood withdrawal used for retransfusion after cardiopulmonary bypass

BACKGROUND

Intraoperative autologous blood withdrawal protects the pooled blood from the deleterious effects of cardiopulmonary bypass. Following reinfusion after cardiopulmonary bypass, the fresh autologous blood contributes to less coagulation abnormalities and reduces postoperative bleeding and the need for allogeneic blood products. However, few data have been available concerning the quality and potential activation of fresh blood stored at room temperature in the operating room.

METHODS

Forty coronary artery bypass grafting patients undergoing a consistent intraoperative and postoperative autotransfusion protocol had a median of 1,000 mL of autologous blood withdrawn before cardiopulmonary bypass. After heparinization the blood was drained from the venous catheter via venous cannula into standard blood bags and stored in the operating room until termination of cardiopulmonary bypass. Samples for hemostatic and inflammatory markers were taken from the pooled blood immediately before it was returned to the patient.

RESULTS

There was some activation of platelets in the stored autologous blood, as measured by an increase of beta-thromboglobulin. Indications of thrombin formation, as assessed by plasma levels of thrombin-antithrombin complex and prothrombin fragment 1.2 were not seen, and there was no fibrinolytic activity. The red blood cells remained intact, indicated by the absence of plasma free hemoglobin. As for the inflammatory response, the levels of the terminal complement complex remained stable, and the cytokines tumor necrosis factor-alpha and interleukin 6 levels were not increased during storage. The complement activation products increased minimally, but remained within normal ranges.

CONCLUSIONS

Except for slight activation of platelets, there was no indication of coagulation, hemolysis, fibrinolysis, or immunologic activity in the autologous blood after approximately 1 hour of operating room storage. The autologous blood was preserved in a condition of high quality, and retransfusion after cardiopulmonary bypass represents an uncomplicated and almost costless procedure for blood conservation.

Processing and transfusion of residual cardiopulmonary bypass volume: effects on haemostasis, complement activation, postoperative blood loss and transfusion volume

The aim of this prospective randomized study was to compare the effects of the transfusion of unprocessed and cell saver-processed residual cardiopulmonary bypass (CPB) volume on haemostasis, complement activation, postoperative blood loss and transfusion requirements after elective cardiac surgery. Blood samples were taken at eight points in time, perioperatively. Haematological data, including haemoglobin, haematocrit and platelet counts as well as coagulation parameters, including activated partial thromboplastin time, prothrombin time, thrombin time, fibrinogen and the fibrinolytic parameter D-dimers, were measured from each blood sample. For the assessment of complement activation, the total complement CH50 was analysed. In addition, postoperative blood loss and transfusion requirements were measured during the first 24 hours, postoperatively. The results of the study showed impaired haemostasis after the transfusion of both unprocessed and processed CPB volume. No significant differences were found between the groups in the measured coagulation parameters. Nor was a significant difference found in the complement concentration. However, in patients transfused with unprocessed CPB volume, a significantly (p = 0.019) higher amount of blood loss was found, postoperatively. In the same group of patients, the number of units of allogeneic erythrocyte concentrate suspension transfused was also significantly (p = 0.023) higher during the first 24 hours, postoperatively, compared to the patients transfused with processed CPB blood. The number of units of fresh frozen plasma and platelet suspension transfused was not significantly different between the groups. In conclusion, processing CPB volume in combination with processing peroperative blood loss may result in reducing the volume of transfusion needed of allogeneic blood products.

Heparin-coated circuits (Duraflo II) with reduced versus full anticoagulation during coronary artery bypass surgery

BACKGROUND

Introduction of completely heparin-coated cardiopulmonary bypass (CPB) circuits combined with reduced systemic anticoagulation has been shown to reduce postoperative bleeding and requirements for allogeneic transfusions after cardiac surgery. However, some uncertainty exists whether this effect is due to the reduced amount of heparin or to the heparinized surface itself. Therefore, a retrospective study was undertaken, comparing two different anticoagulation protocols applied to coronary artery bypass patients treated with identical heparin-coated CPB equipment.

METHOD

Over a 12 month period all coronary artery bypass patients operated with extracorporeal circulation were subjected to a Duraflo II heparin-coated circuit (Baxter Healthcare Corp, Bentley Laboratories Division, Irvine, Calif) and full heparin dose (activated clotting time [ACT] > 480 seconds; Group F, n = 651). Over the next 24 months, all coronary patients who were treated with an identical circuit combined with reduced systemic heparinization (ACT > 250 seconds) were included in Group R (n = 675). Except for the different anticoagulation protocols, all treatment regimens before, during, and after the operation remained unchanged throughout the study period.

RESULTS

There were no statistically significant differences in any major demographic or operative parameters. In Group R, the postoperative bleeding was mean 665 +/- 257 ml versus 757 +/- 367 ml in Group F (p < 0.0001), and the perioperative decrease in hemoglobin concentration was significantly lower in Group R (22 +/- 1.2 gm/L versus 25 +/- 1.3 gm/L, p < 0.0001). The time for postoperative ventilatory support was shorter in Group R (1.7 +/- 1.3 hours versus 1.9 +/- 1.1 hours in Group F, p = 0.0006), and the incidence of new episodes of atrial fibrillation after the operation was lower (26.4% in Group R versus 32.8% in Group F, p = 0.01). There were no significant differences in the incidences of perioperative myocardial infarction, stroke, transient neurological disturbances, physical rehabilitation, or mortality. No technical or coagulation problems were recorded in either group.

CONCLUSION

The use of Duraflo II coated circuits for CPB combined with reduced anticoagulation decrease postoperative bleeding and hemoglobin loss compared with full heparin dose treatment. In addition, the intubation time was shorter and the incidence of postoperative atrial fibrillation was lower in the patients treated with low heparin doses.

Coagulation, fibrinolysis, and cell activation in patients and shed mediastinal blood during coronary artery bypass grafting with a new heparin-coated surface

OBJECTIVES

Heparin coating of the cardiopulmonary bypass circuit is shown to improve the biocompatibility of the surface. We have studied a new heparin surface, the Corline Heparin Surface, applied to a complete set of an extracorporeal device used during coronary artery bypass grafting in terms of activation of inflammation, coagulation, and fibrinolysis in patients and in shed mediastinal blood.

METHODS

Sixty patients scheduled for coronary artery bypass grafting were randomized to one of 3 groups with heparin-coated devices receiving either a standard, high, or low dose of systemic heparin or to an uncoated but otherwise identical circuit receiving a standard dose of systemic heparin. Samples were drawn before, during, and after the operation from the pericardial cavity and in shed mediastinal blood. No autotransfusion of shed mediastinal blood was performed.

RESULTS

The Corline Heparin Surface significantly reduced the activation of coagulation, fibrinolysis, platelets, and inflammation compared with that seen with the uncoated surface in combination with a standard dose of systemic heparin during cardiac surgery with cardiopulmonary bypass. Both a decrease and an increase of systemic heparin in combination with the coated heparin surface resulted in higher activation of these processes. A significantly higher expression of all studied parameters was found in the shed mediastinal blood compared with in systemic blood at the same time.

CONCLUSIONS

The Corline Heparin Surface used in cardiopulmonary bypass proved to be more biocompatible than an uncoated surface when using a standard systemic heparin dose. The low dose of systemic heparin might not be sufficient to maintain the antithrombotic activity, and the high dose resulted in direct cell activation rather than a further anti-inflammatory and anticoagulatory effect.

Clinical effects of different protamine doses after cardiopulmonary bypass

The optimal dose of protamine needed to reverse the anticoagulant effect of heparin after cardiopulmonary bypass is still not known. In this retrospective cohort study, we investigated 3 different dose regimes in 300 patients undergoing coronary artery bypass grafting. Group A patients (n = 100) were given protamine in the ratio of 1.3 mg to 1 mg heparin, group B patients (n = 100) were given 0.75 mg protamine to 1 mg heparin, and group C patients (n = 100) were given protamine in fractionated doses of 1 mg + 0.15 mg + 0.15 mg to 1 mg heparin. The groups were comparable in all major clinical and operative variables. The heparin dose was almost identical in the groups. The rate of red cell transfusion was significantly higher in group B than in the other groups. A similar but nonsignificant trend was observed in the incidence of resternotomy for postoperative bleeding, mediastinal drainage, and postoperative hemoglobin loss. The study demonstrates that a single bolus dose of 1.3 mg protamine to 1 mg heparin is safe and efficient for neutralizing heparin after cardiopulmonary bypass.

Troponin I concentrations of shed blood might influence monitoring of myocardial injury after coronary operations

In a prospective study we evaluated the concentration of cardiac troponin I (cTnI) and creatine kinase activities (CK) in shed mediastinal blood in the early postoperative period after coronary artery bypass grafting (CABG). Forty seven patients who underwent first time elective CABG were studied. CTnI levels and CK activities in arterial blood and shed mediastinal blood were measured after admission to the intensive care unit (ICU) and 6 h after unclamping the aorta. Mediastinal shed blood samples were drawn from 23 patients (group A) before the filter of the cardiotomy reservoir and from 24 patients (group B) behind. Additionally, both markers were measured in blood samples collected from the cell-saver. There were no significant differences between both groups (A and B) with regard to perioperative parameters. Mean loss of mediastinal shed blood in all patients was 207 +/- 127 ml within the first 6 h after operation. There was a positive correlation between CK activities and cTnI concentrations in serum and mediastinal shed blood, but shed blood contained significantly higher concentrations of cTnI as well as CK activities than the circulating blood after admission to the ICU and 6 h after unclamping the aorta. At both time points the cTnI-concentrations and CK activities in shed blood in group B were lower than those in group A but much higher than in serum. The effects of the use of a blood filter diminishes with time. Mediastinal shed blood contains extremely high cTnI concentrations and CK activities. Retransfusion of higher quantities of shed blood might lead to false-positive diagnosis of perioperative myocardial infarction.