Study of five cell salvage machines in coronary artery surgery

Risk factors associated with positive bacterial culture in salvaged red blood cells during cardiac surgery and postoperative infection incidence: A prospective cohort study

Background

This study was designed to explore factors associated with the incidence of positive bacterial culture of salvaged red blood cells (sRBCs) recovered with a Cell Saver instrument during cardiac surgery and the impact of such positive outcomes on postoperative infection-related morbidity.

Methods

The cohort study enrolled 204 patients scheduled for cardiac surgery with intraoperative blood cell salvage and retransfusion from July 2021 to July 2022. These patients were stratified into two groups based on intraoperative sRBCs bacterial culture results: culture (+) and culture (-) groups. Preoperative and intraoperative variables were compared between these groups aim to detect possible predictors of positive culture in sRBCs. In addition, differences in postoperative infection-related morbidity and other clinical outcomes were compared between these groups.

Results

Of these patients, 49% were sRBCs culture (+), with Staphylococcus epidermidis as the most commonly identified pathogen. Risk factors independently associated with the risk of positive culture in sRBCs included BMI ≥25 kg/m², a history of smoking, an operative duration ≥277.5 min, the higher number of staff in the operating room and higher surgical case order. Patients in the sRBCs culture (+) group exhibited a longer average ICU stay [3.5 days (2.0-6.0) vs. 2 days (1.0-4.0), P < 0.01], a longer duration of ventilation [20.45 h (12.0-17.8) vs. 13 h (11.0-17.0, P = 0.02)], underwent more allogeneic blood transfusions, exhibited higher transfusion-related costs [2,962 (1,683.0-5,608.8) vs. 2,525 (1,532.3-3,595.0), P = 0.01], and had higher rates of postoperative infections (22 vs. 9.6%, P = 0.02) as compared to patients in the sRBCs culture (-) group. In addition, culture (+) in sRBCs was an independent risk factor for postoperative infection (OR 2.62, 95% CI 1.16-5.90, P = 0.02).

Conclusion

Staphylococcus epidermidis was the most common pathogen detected in sRBCs in the culture (+) group in this study, identifying it as a potential driver of postoperative infection. Positive sRBCs culture may contribute to postoperative infection and its incidence was significantly associated with patient BMI, history of smoking, operative duration, the number of staff in the operating room and surgical case order.

The Optimal Cell Salvage Settings to Maximize Hematocrit and Minimize Potassium Using the Cobe BRAT2 Autologous Blood Recovery Unit

OBJECTIVE

The objective was to determine the optimal cell saver device settings (infusion rate and wash rate) at which hematocrit is preserved and potassium and lactate are removed from banked red blood cells (RBC).

DESIGN

Red cells were washed using the Cobe BRAT 2 Autologous Blood Recovery Unit and sampled for electrolyte composition and hematocrit pre- and postwash.

SETTING

This was a single-center study.

INTERVENTIONS

Red cells were washed using six infusion rates (100-1,000 mL/min) and six wash rates (100-1,000 mL/min) for a total of 36 combinations. Hematocrit, potassium, glucose, and lactate were evaluated before and after washing.

MEASUREMENTS AND MAIN RESULTS

At wash rates ≤400 mL/min, hematocrit increased independent of infusion rate. At wash rates ≥400 mL/min, slower infusion rates were associated with higher hematocrit compared to faster infusion rates (p < 0.0001 for a wash rate 400-800 mL/min, p < 0.0005 for a wash rate 1,000 mL/min). Maximal wash speeds were associated with decreasing hematocrit. Infusion and wash rate were both independent predictors of potassium change; slower rates were associated with a larger decrease in potassium. Glucose decreased proportionally as infusion and wash rate decreased. Lactate did not show an association with either infusion or wash rate.

CONCLUSION

Red-cell washing produces higher hematocrit and lower potassium as infusion rate and wash rate decrease. A 340-mL unit of RBC can be processed in 4.26 minutes without loss of hematocrit or an increase in potassium when both infusion and wash rates are set to 400 mL/min.

Influence of cardiopulmonary bypass set-up and management on clinical outcomes after minimally invasive aortic valve surgery

INTRODUCTION

Minimally invasive aortic valve replacement (MIAVR) requires changes in cannulation strategy and cardiopulmonary bypass (CPB) management when compared to the conventional approach (CAVR). We aimed at evaluating if these differences could influence perfusion-related quality parameters and impair postoperative outcomes.

METHODS

Overall, 339 consecutive patients underwent MIAVR or CAVR between 2014 and 2020 and were analyzed retrospectively. To account for baseline differences, a propensity-matching analysis was performed, obtaining two groups of 97 patients each.

RESULTS

MIAVR group had longer CPB time [107 (95-120) vs 95 (86-105) min, p = .003] than CAVR group. Of note, average pump flow rate index [2.4 (2.2-2.5) vs 2.7 (2.4-2.8) l/min/m², p = .004] was lower in the MIAVR group. Mean arterial pressure was 73 = 9 mmHg vs 62 = 11 mmHg for the MIAVR and CAVR group, respectively (p < .001). Cell-salvaged blood was most commonly used in the MIAVR group (25.8% vs 11.3%, p = .02). Finally, CPB temperature was 32.8°C (32.1-34.8) for MIAVR group vs 34.9°C (33.2-36.1) for the CAVR group (p = .02). Postoperative complications were similar between groups.

CONCLUSIONS

In conclusion, despite differences in CPB parameters in patients undergoing CAVR and MIAVR, the incidences of adverse outcomes were similar. However, compared to CAVR, MIAVR was associated with shorter durations of mechanical ventilation and hospital stay as well as less transfusion of blood products.

Extensive cell salvage and postoperative outcomes following thoracoabdominal and descending aortic repair

OBJECTIVE

Cell salvage (CS) reduces intraoperative blood transfusion. However, it may cause deformity of the red blood cells and loss of coagulation factors, which may lead to unwanted sequelae. Thus, we hypothesized that extensive CS would lead to adverse outcomes after descending/thoracoabdominal aortic aneurysm (D/TAAA) repair.

METHODS

Between 1991 and 2017, 2012 patients undergoing D/TAAA repair were retrospectively reviewed. After we excluded patients without reported intraoperative CS amount, patients were enrolled in the study (N = 1474) and divided into 2 groups: low CS (salvaged units <40, N = 983) and high CS (salvaged units ≥40, N = 491). Analyses were performed to verify the extensive CS as the risk factor for adverse outcomes.

RESULTS

Preoperative demographics showed that the high-CS group had a significantly greater incidence of male patients (72% vs 58%), heritable aortic disease (24% vs 17%), redo (27% vs 20%), greater glomerular filtration rate (mL/min/1.73 m², 75 vs 66) and more extensive aneurysms (TAAA extent II-IV). The high-CS group had significantly more postoperative complications compared with the low-CS group, including respiratory failure, renal failure, cardiac complications, neurologic deficits, bleeding, and 30-day mortality. Multivariable analysis confirmed high CS was an independent risk factor for renal failure along with long bypass time, older age, and extent of repairs. There was an incremental risk of renal failure and 30-day mortality proportional to salvaged cell unit (P < .001 in both).

CONCLUSIONS

Increased salvaged cell units were associated with adverse postoperative outcomes after D/TAAA repairs. Risk of renal failure and mortality increased proportionally to the salvaged cell units.

Acute Kidney Injury Secondary to Cell Saver in Posterior Spinal Fusion

BACKGROUND

Autologous blood transfusion, commonly referred to as cell saver, is frequently used in spinal fusion to salvage red blood cells because of the risk of significant intraoperative blood loss. This case report describes a case of acute kidney injury (AKI) secondary to cell saver use. Our objective is to increase the knowledge about the process of red blood cell salvage and this exceedingly rare complication.

METHODS

Chart and renal biopsy results for a single case were reviewed and reported in this retrospective study.

RESULTS

A healthy 18-year-old male patient underwent posterior spinal instrumentation and fusion for adolescent idiopathic scoliosis with utilization of intraoperative autologous blood transfusion. The patient subsequently developed hematuria and AKI with a peak creatinine of 13.9 mg/dL. An extensive clinical workup, including autoimmune serology, excluded any identifying causes. A renal biopsy showed pigment-induced acute tubular necrosis.

CONCLUSIONS

This case, to our knowledge, is the first and only case report of AKI secondary to cell saver demonstrated by renal biopsy. The literature has shown both the benefit of cell saver by decreasing the need for allogeneic transfusion and the risk of transient hematuria. However, this case demonstrates the importance of monitoring patients for potential complications.

Performance of a new-generation continuous autotransfusion device including fat removal and consequences for quality controls

BACKGROUND AND OBJECTIVES

Cell salvage plays a key role in blood conservation. To maintain high performance, quality management is recommended. Accordingly, a new-generation autotransfusion device was tested for its performance and compared with its predecessor. Two different calculations of quality parameters were applied.

MATERIALS AND METHODS

In an experimental study, the continuous autotransfusion devices CATSmart and Continuous Autotransfusion System (C.A.T.S) plus were tested using banked blood adjusted to a haematocrit of 20% and anticoagulated with heparin 5 U/L. Test blood was processed using an emergency programme, a high-quality programme/smart wash programme and a low-volume wash programme. Samples were taken after the production of 200 mL of red blood cells (RBC) and after the final emptying of the separation chamber. In an additional set of tests, blood containing 1·25% fat was processed with both devices to examine fat removal.

RESULTS

Both devices demonstrated an equally high performance with regards to product hematocrit (Hct); RBC recovery; and elimination rates of protein, heparin and fat. The high fat elimination rate (>99·8%) reported for C.A.T.S plus was confirmed for CATSmart, regardless of the used programme. Samples taken during the ongoing process show a higher haematocrit and RBC recovery rate than samples taken after the final emptying of the separation chamber. Interface sensors were not affected by fat in the blood.

CONCLUSIONS

The new-generation autotransfusion device CATSmart is not inferior to its predecessor and shows high performance with regards to RBC recovery, plasma and fat elimination in all programme modes. Samples for quality controls should be taken during blood processing.

Fat removal during cell salvage: an optimized program for a discontinuous autotransfusion device

BACKGROUND

Fat in wound blood observed in orthopedic or cardiac surgery might pose a risk for fat embolism during blood salvage. Fat removal was optimized in the washing process.

STUDY DESIGN AND METHODS

In an experimental study blood from fresh donations was adjusted to a hematocrit (Hct) of 25% and an admixture of 1.25% human tissue fat. This blood was processed with the cell salvage device XTRA in a modified program mode. Volumetric quantification of fat was performed after centrifugation of blood samples in Pasteur pipettes. From the volumes, the Hct levels and the concentrations of fat and other variables elimination rates and RBC recovery were calculated.

RESULTS

Pretests showed wash volume, wash flow, and process interruptions affecting fat elimination. With the new optimized fat elimination program Pfat removal rate of fat increased to 98.5 ± 0.9% for the 225-mL bowl. The product had a mean Hct of 48.7 ± 1.2% and a RBC recovery rate of 93.5 ± 2.3%. The program conserved the high elimination rates for albumin, heparin, potassium, and free plasma hemoglobin (98.8, 99.3, 95.3, and 94.9%, respectively). Similar high fat removal was also observed with bowls of smaller size, namely, 98.1% for the 175-mL bowl and 98.2% for the 125- and the 55-mL bowls. With test blood of Hct 10% a mean fat elimination of 99.6 ± 01% was observed.

CONCLUSIONS

A special program modification Pfat involving extra washing and RBC concentration steps significantly improves fat removal by the Latham bowl-based autotransfusion device XTRA, thus yielding results equivalent to the continuous cell salvage system.

Pathophysiology of Cardiopulmonary Bypass

The techniques and equipment of cardiopulmonary bypass (CPB) have evolved over the past 60 years, and numerous numbers of cardiac surgical procedures are conducted around the world using CPB. Despite more widespread applications of percutaneous coronary and valvular interventions, the need for cardiac surgery using CPB remains the standard approach for certain cardiac pathologies because some patients are ineligible for percutaneous procedures, or such procedures are unsuccessful in some. The ageing patient population for cardiac surgery poses a number of clinical challenges, including anemia, decreased cardiopulmonary reserve, chronic antithrombotic therapy, neurocognitive dysfunction, and renal insufficiency. The use of CPB is associated with inductions of systemic inflammatory responses involving both cellular and humoral interactions. Inflammatory pathways are complex and redundant, and thus, the reactions can be profoundly amplified to produce a multiorgan dysfunction that can manifest as capillary leak syndrome, coagulopathy, respiratory failure, myocardial dysfunction, renal insufficiency, and neurocognitive decline. In this review, pathophysiological aspects of CPB are considered from a practical point of view, and preventive strategies for hemodilutional anemia, coagulopathy, inflammation, metabolic derangement, and neurocognitive and renal dysfunction are discussed.

Washing older blood units before transfusion reduces plasma iron and improves outcomes in experimental canine pneumonia

In a randomized controlled blinded trial, 2-year-old purpose-bred beagles (n = 24), with Staphylococcus aureus pneumonia, were exchanged-transfused with either 7- or 42-day-old washed or unwashed canine universal donor blood (80 mL/kg in 4 divided doses). Washing red cells (RBC) before transfusion had a significantly different effect on canine survival, multiple organ injury, plasma iron, and cell-free hemoglobin (CFH) levels depending on the age of stored blood (all, P < .05 for interactions). Washing older units of blood improved survival rates, shock score, lung injury, cardiac performance and liver function, and reduced levels of non-transferrin bound iron and plasma labile iron. In contrast, washing fresh blood worsened all these same clinical parameters and increased CFH levels. Our data indicate that transfusion of fresh blood, which results in less hemolysis, CFH, and iron release, is less toxic than transfusion of older blood in critically ill infected subjects. However, washing older blood prevented elevations in plasma circulating iron and improved survival and multiple organ injury in animals with an established pulmonary infection. Our data suggest that fresh blood should not be washed routinely because, in a setting of established infection, washed RBC are prone to release CFH and result in worsened clinical outcomes.

Washing of banked blood by three different blood salvage devices

BACKGROUND

Storage lesions in red blood cells (RBCs) lead to an accumulation of soluble contaminants that can compromise the patient. Organ failures, coagulopathies, and cardiovascular events including lethal cardiac arrest have been reported, especially with massive transfusion or in pediatric patients. Washing improves the quality of stored RBCs, and autotransfusion devices have been proposed for intraoperative processing, but these devices were designed for diluted wound blood, and limited data on their performance with RBCs are available.

STUDY DESIGN AND METHODS

Three autotransfusion devices (Electa, Sorin; CATS, Fresenius; OrthoPAT, Haemonetics) differing in function of their centrifugation chambers were evaluated with RBCs at the end of their shelf life and with dilutions thereof. Elimination rates of potassium, plasma free hemoglobin, total protein, citrate, acid equivalents, and iomeprol added as a marker substance were analyzed, in addition to RBC recoveries.

RESULTS

Product hematocrit (Hct) levels ranged between 54.8 and 72.6%. RBC recovery rates were between 62.7 and 95.0%, the lowest being with the OrthoPAT processing of undiluted RBCs. Plasma elimination rates increased with predilution and ranged from 46.6% to 99.5%, the lowest being with the CATS and undiluted RBCs. Washing did not change pH and buffering capacity of RBCs.

CONCLUSION

Autotransfusion devices offer a practical and obviously economical option to wash banked RBCs intraoperatively to prevent hyperkalemia and other disturbances in massive transfusion or pediatric patients. Predilution improves elimination rates, especially in devices that produce high product Hct levels. With a Y-tubing the RBCs should bypass reservoir and vacuum, and the procedure should be guarded by a policy and procedure manual and a quality management system.

A modified thrombin clotting time test as a quality control marker for heparin contamination in obstetric intraoperative cell salvage

OBJECTIVE

To assess if a modified thrombin clotting time test could be used as a simple quality control (QC) method to screen for unfractionated heparin in the product obtained from obstetric intraoperative cell salvage cases before re-infusion.

BACKGROUND

A national QC scheme has recently been piloted to monitor the quality of autologous blood being returned to the patient. Laboratory tests include full blood count and microalbumin. Unfractionated heparin testing should be performed to ensure that there is no gross contamination of heparin in the final product; however, presently, there is no quick cheap test available suitable for heparin detection.

MATERIALS AND METHODS

Samples were collected into plain non-anticoagulated tubes and centrifuged at 2500 × g for 5 min. Supernatant was mixed with commercially available coagulated normal plasma and a thrombin clotting time test performed.

RESULTS

Calibration runs demonstrated that our system was sensitive up to 0 · 14 IU mL(-1) heparin, linear between 0 · 08 and 0 · 14 IU mL(-1).

CONCLUSION

We have shown that the thrombin clotting time test can be modified and used as a cheap and reliable marker for heparin contamination. We have successfully incorporated this modified test into our hospital's obstetric QC scheme.

A quality assurance programme for cell salvage in cardiac surgery

At the same time as cell salvage was introduced into our institution for all patients undergoing cardiac surgery with cardiopulmonary bypass, we established a supporting programme of quality assurance to reassure clinicians regarding safety and efficacy. Data collected in patients operated on between 2001 and 2007 included pre- and post-wash heparin concentration, haemoglobin concentration and free haemoglobin concentration. Cell salvage was used in 6826 out of a total of 7243 patients (94%). Post-wash heparin concentration was consistently low (always < 0.4 IU.ml(-1)). There was a significant decrease in post-wash haemoglobin concentration in 2003 compared to 2001, from a median (IQR [range]) of 19.6 (16.7-22.2 [12.9-25.5]) g.dl(-1) to 17.5 (13.6-20.8 [12.6-23.7]) g.dl(-1) (p < 0.015). In addition, there was a significant increase in free plasma haemoglobin in 2006 compared to 2001, from 0.5 (0.3-0.8 [0.1-2.6]) g.l(-1) to 0.8 (0.3-1.4 [0.3-5.2]) g.l(-1) (p < 0.001). This programme led to the detection of a change in operator behaviour in 2003 and progressive machine deterioration resulting in appropriate fleet replacement in 2006. You can respond to this article at http://www.anaesthesiacorrespondence.com.

Comparison of the use of minimized cardiopulmonary bypass with conventional techniques on the incidence of retinal microemboli during aortic valve replacement surgery

OBJECTIVES

Minimized cardiopulmonary bypass (MCPB) circuits have been shown to reduce cerebral and retinal microembolisation during coronary artery bypass graft (CABG) surgery compared to conventional CPB (CCPB) circuits. Our aim was to evaluate whether the reduction of microembolisation is sustained in aortic valve surgery, as well as to evaluate the effects of MCPB on inflammatory, endothelial, and platelet activation markers.

MATERIAL AND METHODS

Patients were randomized to undergo aortic valve replacement (AVR), with or without CABG, with MPCB (n=20) or CCPB (n=20). After anaesthesia induction and termination of CPB, standardized digital retinal fluorescein angiography images were obtained on both eyes and analyzed in a blinded fashion. Blood samples were collected at eight time points until the third postoperative day.

RESULTS

Fewer patients in the MCPB group showed evidence of microembolic perfusion defects on postperfusion retinal fluorescein angiographs compared to the CCPB group (37% vs. 63%, absolute difference 26%, 95% CI -5% -51%, P = 0.194). Polymorphonuclear leukocyte (PMN) elastase and von Willebrand factor release were statistically significantly reduced in the MCPB group, but there were no significant differences in other markers of inflammation, coagulation or endothelial activation. A significantly higher three-fold increase in the amount of shed blood was collected to the cell saver with a higher rate of intraoperative platelet transfusion in the MCPB group compared to CCPB.

CONCLUSIONS

The use of MCPB was associated statistically insignificantly with less retinal microemboli compared to CCPB. MCPB was complicated by excess bleeding and need for transfusion. The feasibility of MCPB techniques in valve surgery requires further studies.

Intraoperatively salvaged red blood cells contain nearly no functionally active platelets, but exhibit formation of microparticles: results of a pilot study in orthopedic patients

BACKGROUND

Previous data show improved clot formation after retransfusion of salvaged red blood cells (RBCs). This study was conducted to explore whether such RBCs contain clinically relevant numbers of active residual platelets (PLTs) or exhibit formation of microparticles (MPs).

STUDY DESIGN AND METHODS

Thirteen patients undergoing major orthopedic surgery were included in the study, and arterial blood samples from patients and samples from the retransfusion bag were analyzed with various PLT function tests and flow cytometry.

RESULTS

With commercial blood cell counters, the numbers of PLTs in the RBC unit were reduced to approximately 25% compared to patients' blood. In contrast, results from flow cytometry showed an 11- to 945-fold reduction in median counts referring to total PLTs and free PLTs. Interestingly, smaller quantities of PLT-derived MPs were found in samples from the retransfusion bag than in patients' arterial blood. Conversely, RBC- and white blood cell-derived MP counts were increased in the retransfusion bag compared to the patient. Rotational thrombelastometry and the Impact-R system (DiaMed) showed a pronounced impairment of PLT ability with regard to adhesion, aggregation, and clot formation. With the use of confocal microscopy, only a few free thrombocytes were detectable among the huge numbers of RBCs.

CONCLUSION

Only few free and thus active PLTs are detectable in processed RBCs. It seems very unlikely that these few PLTs can improve clot strength. Nevertheless, the impact of the detected MPs on thrombin generation needs to be clarified in further studies.

Re-transfusion of salvaged washed red cells improves clot formation in pigs as measured by rotational thrombelastometry (ROTEM)

BACKGROUND AND OBJECTIVE

Patients exhibiting considerable blood loss are prone to develop dilutional coagulopathy following volume supply. In such patients, in addition to transfusing stored blood components, cell saver systems are used to minimize allogeneic transfusion. Since red cell transfusion might influence the haemostatic system by further dilution, we investigated the effects of re-transfusion of salvaged washed red blood cells on the haemostatic process in an animal model of controlled haemorrhage using rotational thrombelastometry (ROTEM; Pentapharm Co., Munich, Germany).

METHODS

Anaesthetized pigs (n = 20) developed coagulopathy following haemorrhagic shock (withdrawal of 66% of estimated blood volume) and volume resuscitation with 6% hydroxyethyl starch 130/0.4. The shed blood was processed in a Cellsaver device (CATS; Fresenius AG, Bad Homburg, Germany), and the resulting salvaged red blood cells were re-transfused. ROTEM assays were performed at baseline, after blood loss, after volume resuscitation and following re-transfusion of salvaged red blood cells.

RESULTS

As compared with baseline, blood loss and subsequent volume resuscitation resulted in significantly increased median values of clotting time (CT: 47.0, 5 .3 and 103.5 s), and clot formation time (CFT: 36.0, 40.0 and 186.0 s), whiggle maximum clot firmness decreased (MCF: 72.0, 68.5 and 39.5 mm). After re-transfusion of salvaged red blood cells (805 +/- 175 mL) all these parameters improved (CT: 80.5 s; P = 0.05, CFT: 144.0 s; P = 0.0008, MCF: 42.0 mm; P = 0.0019) although baseline values were not reached.

CONCLUSION

In the case of extreme isovolaemic haemodilution, increasing the circulating red cell mass by re-transfusing salvaged red blood cells did not worsen the findings of dilutional coagulopathy but interestingly, at least partially, improves the clot formation process.

Coagulation and fibrinolytic protein kinetics in cardiopulmonary bypass

The development of Cardiopulmonary Bypass (CPB) catopulted the field of cardiothoracic surgery into a new dimension--one that changed the lives of individuals with congenital and acquired heart disease worldwide. Despite its contributions, CPB has clear limitations and creates unique challenges for clinicians and patients alike, stemming from profound hemostatic pertubations and accompanying risk for bleeding and possibly thrombotic complications.

Thrombin generation assay and viscoelastic coagulation monitors demonstrate differences in the mode of thrombin inhibition between unfractionated heparin and bivalirudin

BACKGROUND

Coagulation tests, such as activated partial thromboplastin time and activated clotting time, are used to monitor the effects of unfractionated heparin and the direct thrombin inhibitor, bivalirudin. These tests reflect only the initial phase of blood clotting, when <5% of thrombin has been formed. In this study, we sought to determine if similar increases in activated partial thromboplastin time or activated clotting time due to heparin or bivalirudin would reflect the same degree of inhibition of thrombin formation.

METHODS

Thrombin formation was evaluated in platelet-poor plasma activated in the presence of heparin (0-5 U/mL) or bivalirudin (0-30 microg/mL) using a thrombin generation assay (Thrombinoscope). Prothrombin activation was measured by prothrombin fragment 1.2 (F1.2) formation. Thrombus formation was further evaluated in kaolin-activated whole blood samples containing heparin (1.5 or 2.5 U/mL) or bivalirudin (12.5 or 25 microg/mL) using Sonoclot and thromboelastography.

RESULTS

Based on the Thrombinoscope results, increasing concentrations of bivalirudin and heparin progressively delayed the onset of thrombin formation, but only heparin dose-dependently decreased the amount of thrombin generated. Heparin and bivalirudin delayed the onset of F1.2 formation, but there was no difference in peak F1.2 levels between bivalirudin and non-anticoagulated samples (206 +/- 28.2 vs 182 +/- 23.9 nmol/L, P = 0.09). In heparinized samples, F1.2 levels were significantly lower (75.7 +/- 29.8 nmol/L, P < 0.05) than controls. Heparin and bivalirudin prolonged the onset of clotting on viscoelastic monitors, but only heparin decreased the rate of thrombus formation.

CONCLUSION

Thrombus formation kinetics differs between heparin and bivalirudin despite similar prolongation of clotting test values.

Successful repair of a giant abdominal aortoiliac aneurysm in a Jehovah's Witness

We report the case of a 76-year-old man of the Jehovah's Witness faith who had a giant abdominal aortoiliac aneurysm that was successfully operated on using an aortoiliac Y-graft bypass technique, without the use of stored allogenic blood. Cell saver technique and recombinant human erythropoietin (epoetin beta) were used during the perioperative period. The patient had good postoperative care with a multidisciplinary approach.

Aprotinin Shows Both Hemostatic and Antithrombotic Effects During Off-Pump Coronary Artery Bypass Grafting

BACKGROUND

Hemostatic drugs are widely thought to be unnecessary and potentially detrimental in off-pump coronary artery bypass graft surgery (OPCABG), despite well-established use in on-pump surgery. In a randomized, prospective OPCABG trial, we assessed efficacy and safety of aprotinin through a comprehensive assessment of graft patency and hematologic function.

METHODS

Sixty patients were randomly assigned to full-dose aprotinin or placebo. Heparin was titrated to a kaolin-based activated clotting time of greater than 300 seconds. Exclusionary criteria included creatinine greater than 2 mg/dL, conversion to on-pump CABG, and preoperative GPIIb/IIIa inhibition. Hematologic assessments were obtained preoperatively, at the end of surgery, and on days 1 and 3: mean platelet volume, thrombin generation (prothrombin fragment 1.2 assay), and aspirin resistance using a modified thrombelastography, whole blood aggregometry, 11-dehydro-thromboxane B2 levels, and flow cytometry. Thrombotic events were defined as postoperative myocardial infarction by electrocardiography or elevated troponin I, clinical stroke by examination and head computed tomography, and bypass graft failure by multichannel computed tomography angiography on day 5.

RESULTS

Aprotinin was associated with a significant reduction in intraoperative and postoperative blood loss compared with placebo but had no effect on transfusion rates. Patients treated with aprotinin had significantly fewer thrombotic events (3% versus 23%, p < 0.05, Fisher's exact test) and less postoperative aspirin resistance (20% versus 46%, respectively, p < 0.05, Fisher's exact test). Postoperative prothrombin fragment 1.2 level was reduced by aprotinin use.

CONCLUSIONS

Aprotinin reduced perioperative bleeding after OPCABG. Preserved aspirin sensitivity in the aprotinin group may explain the observed reduction in thrombotic events and might be related to the suppression of perioperative and transmyocardial thrombin formation.

Activation of blood coagulation in patients undergoing postoperative blood salvage and re-infusion of unwashed whole blood after total knee arthroplasty

BACKGROUND

Perioperative blood salvage is commonly used in cardiovascular surgery and has been more recently introduced in major orthopedic surgery. Limited information is available on the influence of re-infused whole blood on the hemostatic system in orthopedic patients.

MATERIALS AND METHODS

The aim of this study was to assess whether perioperative salvage and re-infusion of unwashed whole blood is associated with an activation of blood coagulation in patients undergoing total knee replacement. Consecutive patients receiving re-infusion were included in the study (n=13). Patients undergoing total knee replacement without perioperative blood salvage and re-infusion served as controls (n=6). In patients receiving re-infusion thrombin-antithrombin complexes (TAT), plasmin-antiplasmin complexes (PAP) and fibrinogen were assayed at the following times: before surgery (baseline), immediately before re-infusion (T0), immediately (T1), 2 h (T2) and 24 h (T3) after the end of re-infusion. In control patients blood samples were drawn at the average times corresponding to each of the sampling time in the patients receiving re-infusion. The first post-surgery LMWH dose was given within 12 h after surgery.

RESULTS

TAT and PAP increased after surgery both in patients receiving re-infusion and controls. An increase of TAT and PAP was observed immediately after re-infusion with respect to baseline (TAT 513.1 +/- 259.1 microg/l vs. 5.3 +/- 4.9, p<0.0001; PAP 7408.0 +/- 1892.1 microg/l vs. 461.4 +/- 217.1, p<0.0001) and to controls (TAT 60.4 +/- 26.9 microg/l, p=0.002; PAP 2208.3 +/- 1446.4 microg/l, p<0.001). The levels of TAT and PAP in patients receiving re-infusion remained high at 2 h after re-infusion compared to those of the controls (TAT 124.1 +/- 38.3 microg/l vs. 38.08 +/- 18.9, p=0.016; PAP 5690.7 +/- 1435.5 microg/l vs. 1613.9 +/- 706.0, p<0.001) and decreased 24 h thereafter. Fibrinogen level was lower in patients receiving re-infusion compared to controls.

CONCLUSIONS

Whole blood re-infusion is associated with an activation of blood coagulation in patients undergoing total knee replacement. The clinical relevance of this activation has to be tested in prospective studies with adequate sample size.