Sylvain Bélisle

Hemorrhage and the Use of Blood Products After Adult Cardiac Operations: Myths and Realities

BACKGROUND Several patient-, procedure-, and prescriber-related factors are thought to influence the decision to administer allogeneic blood products. We reexamine a number of assertions applied commonly to the practice of transfusion in cardiac operations. METHODS More than 50 original articles including a total of more than 10,000 patients from 70 centers were reviewed. Data from 5,426 patients operated on between 1990 and 1994 at the Montreal Heart Institute are presented. RESULTS From our review of the literature, we conclude that postoperative mediastinal fluid drainage averages 917 mL and that aspirin therapy increases drainage by less than 300 mL in most studies, which should not increase use of blood products, insofar as a strict transfusional protocol is adhered to. Across centers, transfusions can vary eightfold for the same postoperative drainage. Data from our institution show that postoperative mediastinal drainage per se is not influenced by reoperation or by the type of operation. However, total blood losses and transfusion requirements remain increased in reoperative and complex procedures. Excessive mediastinal drainage resulting in increased transfusions occurs in 29% of patients. CONCLUSIONS Exposure to allogeneic transfusions remains institution dependent. Constant reevaluation of local practice is essential to implement efficient blood conservation strategies.

Prophylactic Tranexamic Acid and ϵ-Aminocaproic Acid for Primary Myocardial Revascularization

Abstract Background . The efficacy of prophylactic ϵ-aminocaproic acid and tranexamic acid to reduce transfusions after primary myocardial revascularization was evaluated in a teaching hospital context. Methods . Patients (n = 134) received either ϵ-aminocaproic acid (15-g bolus + infusion of 1 g/h), high-dose tranexamic acid (10-g bolus + placebo infusion), or normal saline solution in a double-blind fashion. Anticoagulation and conduct of cardiopulmonary bypass were standardized. Results . Tranexamic acid and ϵ-aminocaproic acid produced a significant reduction in postoperative blood loss compared with placebo (median loss, 438 mL, 538 mL, and 700 mL, respectively). Transfusion of red cells was similar in all three groups. Nonetheless, the percentage of patients receiving hemostatic blood products was significantly decreased in the ϵ-aminocaproic acid group compared with the placebo group (20% versus 43%; p = 0.03). Both tranexamic acid and ϵ-aminocaproic acid significantly decreased total exposure to allogeneic blood products compared with placebo ( p = 0.01 and p = 0.05, respectively), and this reduction was clinically important (median exposure, 2, 2, and 7.5 units, respectively). Fibrinolysis was inhibited significantly in both treatment groups. Conclusions . We conclude that either high-dose tranexamic acid or ϵ-aminocaproic acid effectively reduces transfusions in patients undergoing primary, elective myocardial revascularization.

Prevention and treatment of coagulopathy in patients receiving massive transfusions

Patients undergoing massive transfusions frequently develop a coagulopathy, which is already present in a considerable percentage of patients upon admission to the emergency room. This derangement of coagulation may aggravate the bleeding tendency and is associated with significant morbidity and mortality. Existing guidelines for optimal transfusion therapy in massively bleeding patients advocate early administration of crystalloid or colloid fluids in conjunction with transfusion of red cells. And, according to the guidelines, fresh frozen plasma (FFP) and platelets should only be administered when a whole blood volume or more has been replaced and then only in patients with excessive or microvascular bleeding and, at best, according to conventional laboratory coagulation analysis. However, this approach may cause dilution coagulopathy and a further impairment of hemostasis due to direct effects of plasma replacement treatment on platelet-vessel wall interaction and thus compromise haemostatic ability further in severely bleeding patients. In recent years, there has been increasing evidence, although mainly coming from non-randomized studies, that early and more intense replacement of coagulation factors and platelets may improve the outcome in patients undergoing massive transfusion. The recommendations in the existing guidelines are based on the results of conventional coagulation assays such as the activated partial thromboplastin time. However, these assays poorly correlate with clinically relevant coagulopathies [1, 2]. Cell-based whole blood viscoelastical assays such as thromboelastography (TEG) provide quantitative information of the haemostatic process and thus give a profile of the haemostatic changes that occur during clotting. Such tests may provide a better guide for blood component therapy for patients with massive bleeding, although also for these tests the clinical relevance has never been adequately validated [3–5]. It seemed of interest to obtain information on these issues by sending the following questions to experts in the field. Question 1: What is your definition of ‘massive blood transfusion’? Question 2: When treating a patient with massive bleeding, do you still follow the official guidelines i.e. restoration of blood volume initially with cristalloids or colloids followed by packed red cells and subsequently the use of FFP, platelets, cryoprecipitate, and other coagulation concentrates depending on the results of coagulation tests and platelet counts? If no: please explain. Question 3: Or do you follow a more aggressive regimen administering FFP and platelets as part of the standard transfusion program? If so, which FFP:RBC ratio do you apply? Please describe your transfusion policy in detail. Question 4: If you use coagulation parameters in your setting, which tests do you apply? Do you think that the conventional tests are satisfactory for this purpose? If not, please explain why. What would be an acceptable turn-around time for any test? Question 5: Have you evidence that a more aggressive regimen with regard to FFP and platelet transfusions improves outcome? Or do you think FFP and platelet transfusion may be harmful? We received 12 contributions to this Forum. Many of the answers are extensive and contain much detailed information. It is impossible to include all this information in an editorial. The reader is therefore strongly advised to read the answers. Although some participants still use the standard definition of massive transfusion, i.e. 10 units of RBC within 24 h, most now use a different definition. Most

Measurement of heparin concentration in whole blood with the Hepcon/HMS device does not agree with laboratory determination of plasma heparin concentration using a chromogenic substrate for activated factor X.

UNLABELLED Measurement of circulating heparin concentration has been suggested to optimize anticoagulation during cardiopulmonary bypass. The Hepcon/HMS device (Medtronic HemoTec, Inc., Parker, Colo.) uses heparin/protamine titration to quantitatively determine heparin concentration. Extensive validation of this instrument is still lacking. METHODS Agreement between heparin concentrations measured by the Hepcon/HMS system and by laboratory determination was evaluated in 16 patients undergoing cardiac operations. For laboratory determinations, plasma heparin concentration was derived from the measure of anti-Xa activity by means of chromogenic substrate technique. The Hepcon/HMS instrument and cartridges measured whole blood heparin concentration. Samples were analyzed 5 minutes after administration of heparin, 15 and 30 minutes after the start of cardiopulmonary bypass, 5 minutes after aortic unclamping, at the end of cardiopulmonary bypass, and after administration of protamine. Data were plotted and interpreted according to the method of Bland and Altman: First, a difference less than 1.4 U/ml (i.e., +/- 0.7 U/ml) was chosen as acceptable, because it would not cause major difficulties in clinical interpretation; second, the difference between the two measurement techniques was plotted against the mean of the two measures. RESULTS The mean difference (bias) between heparin concentrations derived by the Hepcon/HMS device and those obtained by laboratory determination was as expected for measures performed on whole blood versus plasma (1.45 U/ml). Nevertheless, heparin concentrations derived by the Hepcon/HMS device may be as much as 2.76 U/ml above or 6.17 U/ml below the concentrations measured in the laboratory, differences well outside the predetermined limits of agreement and clearly unacceptable for clinical purposes. CONCLUSION We conclude that heparin concentrations determined with the Hepcon/HMS instrument do not agree with laboratory determination of heparin concentration. Monitoring of heparin concentrations during bypass with the Hepcon/HMS device cannot be recommended.

Natural and synthetic antifibrinolytics in adult cardiac surgery: efficacy, effectiveness and efficiency

Epsilon-aminocaproic acid and tranexamic acid, two synthetic antifibrinolytics, and aprotinin, an antifibrinolytic derived from bovine lung, are used to reduce excessive bleeding and transfusion of homologous blood products (HBP) after cardiac surgery. This review analyzes the studies on the utilization of antifibrinolytics in adult cardiac surgery according to the epidemiological concepts of efficacy, effectiveness and efficiency. A majority of published studies confirm the efficacy of antifibrinolytics administered prophylactically to reduce postoperative bleeding and transfusion of HBP. More studies are needed, however, to compare antifibrinolytics and determine if any one is superior to the others. Despite their demonstrated efficacy, antifibrinolytics are only one of the options available to diminish the use of HBP. Other blood-saving techniques, surgical expertise, temperature during cardiopulmonary bypass and respect of established transfusion guidelines may modify the effectiveness of antifibrinolytics to the point where antifibrinolytics may not be necessary. At this time, insufficient data have been published to perform a cost vs benefit analysis of the use of antifibrinolytics. This complex analysis takes into account not only direct costs (cost of the drug and of blood products), but also the ensuing effects of treatment such as: length of stay in the operating room, in the intensive care unit and in the hospital; need for surgical re-exploration; treatment of transfusion or drug-related complications, etc. In particular, the risk of thrombotic complications associated with antifibrinolytics is the subject of an ongoing, unresolved controversy. In conclusion, it is important for each institution to determine if their patient population (or a subset of this population) is likely to benefit from prophylactic treatment with antifibrinolytics, and to confirm that treatment is not associated with an increased incidence of untoward effects, before engaging in the routine use of any of these medications.RésuméTrois antifibrinolytiques sont présentement utilisés en chirurgie cardiaque afin de réduire le saignement postopératoire et la transfusion de produits sanguins homologues (PSH). Il s’agit de l’acide epsilon-aminocaproïque et de l’acide tranexamique, deux antifibrinolytiques de synthèse, ainsi que de l’aprotinine, un antifibrinolytique naturel isolé à partir de poumons de bovins. Cet article fait une revue de l’utilisation des antifibrinolytiques en chirurgie cardiaque de l’adulte en fonction des concepts épidémiologiques fondamentaux que sont l’efficacité expérimentale, l’efficacité clinique et l’efficience. La majorité des études publiées confirme l’efficacité expérimentale des antifibrinolytiques administrés prophylactiquement dans le but de diminuer le saignement postopératoire et la transfusion de PSH. Cependant, les études cherchant à comparer les antifibrinolytiques entre eux sont rares. Seuls d’autres travaux nous permettront d’établir l’efficacité comparée de ces médicaments. Malgré leur efficacité expérimentale, les antifibrinolytiques ne sont qu’une des options à notre disposition pour diminuer le recours à la transfusion. Ainsi, l’efficacité clinique des antifibrinolytiques sera modifiée par l’utilisation des autres technologies visant à minimiser les pertes sanguines et la transfusion, par l’expertise de l’équipe chirurgicale, par la température durant la perfusion extra-corporelle, ainsi que par le respect des indications bien établies de la transfusion. Ainsi, dans un contexte donné, l’utilisation de ces médicaments pourra même s’avérer superflue. Nous ne disposons pas actuellement de données suffisantes pour compléter une analyse coûts/ bénéfices des antifibrinolytiques en chirurgie cardiaque de l’adulte. Cette analyse complexe devra tenir compte non seulement des coûts directs (médicaments et produits sanguins), mais aussi des effets associés au traitement tels que: durée de séjour en salle d’opération, aux soins intensifs et à l’hôpital; nécessité d’une ré-exploration pour hémostase; traitement des complications secondaires aux transfusions ou aux médicaments, etc. Plus spécifiquement, le risque de complications thrombotiques secondaires aux antifibrinolytiques fait l’objet d’une controverse non résolue à ce jour. En conclusion, avant de procéder à l’administration routinière de ces médicaments, chaque institution devra déterminer, dans la population chirurgicale qui lui est propre (ou dans un sous-groupe de cette population), l’utilité et l’innocuité des antifibrinolytiques administrés prophylactiquement.

Torsades de pointes secondary to intravenous haloperidol after coronary bypass grafting surgery.

Purpose: Postoperative delirium occurs in about 2% of patients undergoing major cardiac surgery including coronary artery bypass grafting surgery (CABG). Haloperidol (Sabex, Boucherville, Canada) is a drug commonly used in the intensive care unit for the treatment of delirium and is usually considered safe even at high doses and is rarely implicated in the development of malignant ventricular arrhythmias such as torsades de pointes. The purpose of this study is to report such a complication of use of haloperidol after myocardial revascularization.Clinical features: The patient reported underwent uneventful triple bypass surgery. Administration of large intravenous doses of haloperidol was necessary for control of psychomotor agitation due to delirium. Torsades de pointes occurred in the absence of QT prolongation on the third postoperative day following use of the drug with no other obvious etiological factor.Conclusion: Awareness of this rare complication is key to judicious use of this drug in the post CABG patient in whom such an arrhythmia may have very deleterious consequences because of the underlying cardiac condition.RésuméObjectif: Le délire postopératoire survient chez environ 2 % des patients qui subissent une intervention cardiaque importante, y compris le pontage aortocoronarien. L’halopéridol (Sabex, Boucherville, Canada) sert habituellement à traiter le délire à l’unité des soins intensifs et est généralement sécuritaire même à de fortes doses. ll est rarement impliqué dans le développement d’arythmies ventriculaires malignes comme les torsades de pointes. l’objectif de la présente étude est de faire état d’une telle complication liée à l’usage d’halopéridol après une revascularisation myocardique.Éléments cliniques: Le patient en question a subi sans problème un triple pontage coronarien. L’administration d’importantes doses intraveineuses d’halopéridol a été rendue nécessaire pour contrôler l’agitation psychomotrice causée par le délire. Les torsades de pointes sont survenues en l’absence de prolongation QT le troisième jour postopératoire après avoir utilisé le médicament. ll n’y avait pas d’évidence d’autre facteur étiologique.Conclusion: Quand on utilise l’halopéridol, il faut savoir que l’arythmie ventriculaire est une complication rare qui peut se présenter chez un patient qui a subi un pontage aortocoronarien et qu7rselle pourrait avoir des conséquences graves, étant donné l’état cardiaque sous-jacent.

Inhaled prostacyclin (PGI2) is an effective addition to the treatment of pulmonary hypertension and hypoxia in the operating room and intensive care unit.

PurposeThere is a growing interest in the intraoperative and intensive care use of inhaled epoprostenol (PGI2) for the treatment of pulmonary hypertension (PHT) and hypoxia of cardiac or noncardiac origin. We report our experience with this form of therapy.MethodsA retrospective chart review of all patients who received inhaled PGI2 over a one-year period was undertaken. Demographic, hemodynamic, oxygenation status, mode of administration, side effects, duration of hospital stay, and mortality were noted.ResultsThirty-five patients, of which 33 (92%) were in the intensive care unit, received inhaled PGI2. Of the 27 patients whose pulmonary artery pressure (PAP) was monitored, a significant decrease in mean PAP from 34.8 ± 11.8 mmHgto 32.1 ± 11.8 mmHg was observed within one hour after the start of therapy (P = 0.0017). Selective pulmonary vasodilatation occurred in 77.8% of the patients. Thirty-three patients had arterial blood gases before and after therapy. There was an improvement in the PaO2/FiO2 ratio in 88% of these with a 175% improvement on average. The ratio of PaO2/FiO2 improved from 108 ± 8 to 138 ± 105 (P = 0.001). Six patients (17%) presented hypotension, two had subsequent pneumothorax, one had bronchospasm and in one patient PGI2 inhalation was stopped because of increasing peak pulmonary pressures from the secondary flow coming from the nebulizer. Mortality of the cohort was 54%.ConclusionInhaled PGI2 can be useful in the treatment of patients with PHT and severe hypoxia. It can however be associated with systemic side effects.RésuméObjectifIl y a un intérêt croissant pour l’utilisation de l’époprosténol (PGI2) inhalé comme traitement de l’hypertension pulmonaire (HTP) et de l’hypoxie d’origine cardiaque ou non survenant en salle d’opération ou aux soins intensifs. Nous rendons compte de notre expérience avec cette forme de thérapie.MéthodeOn a procédé à l’examen rétrospectif de tous les dossiers des patients qui ont reçu de la PGI2 par inhalation au cours d’une année. Les données démographiques et hémodynamiques, l’état de l’oxygénation, le mode d’administration, les effets secondaires, la durée du séjour hospitalier et la mortalité ont été enregistrés.RésultatsTrente-cinq patients, dont 33 (92 %) étaient à l’unité des soins intensifs, ont reçu de la PGI2 par inhalation. Chez 27 patients dont on a surveillé la tension artérielle pulmonaire (TAP), une baisse significative de la TAP moyenne a été observée passant de 34,8 ± 11,8 mmHg à 32,1 ± 11,8 mmHg pendant la première heure de la thérapie (P = 0,0017). La vasodilatation pulmonaire sélective est survenue chez 77,8 % des patients. Trente-trois patients ont eu une gazométrie du sang artériel avant et après la thérapie. Une amélioration du ratio PaO2/FiO2 a été notée chez 88 % d’entre eux et une amélioration de 175 % en moyenne. Le ratio PaO2/FiO2 s’est amélioré, de 108 ± 8 à 138 ± 105 (P = 0,001). Six patients (17 %) ont présenté de l’hypotension, deux ont eu un pneumothorax subséquent, un a souffert de bronchospasme et chez un autre patient l’inhalation de PGI2 a été stoppée à la suite de la hausse des pics de pressions pulmonaires provenant du flux secondaire du nébuliseur. La mortalité a été de 54 % dans cette cohorte.ConclusionLa PGI2 inhalée peut être utile comme traitement de patients atteints d’HTP et d’hypoxie sévère. Il peut toutefois provoquer des effets secondaires systémiques.

Low-dose aprotinin infusion is not clinically useful to reduce bleeding and transfusion of homologous blood products in high-risk cardiac surgical patients

A high-dose regimen of aprotinin 5–6 million KIU is effective in reducing bleeding and the need for homologous blood products (HBP) associated with cardiopulmonary bypass (CPB). These high doses aim at achieving plasmin and plasma kallikrein concentrations which in vitro are inhibitory but, theoretically, smaller doses could suffice in vivo. Also, aprotinin is an expensive drug, so efficiency requires using the smallest effective dose. Therefore, the efficacy of prophylactic aprotinin 1 million KIU (the maximal dose approved currently) was evaluated in a patient population at high risk of bleeding and of being transfused. Forty-one patients undergoing reoperation or a complex surgical procedure were included in a prospective, randomized, placebo-controlled, double-blind study. Before skin incision, a bolus of 200,000 KIU aprotinin was administered in 20 min, followed by an infusion of 100,000 KIU· hr−1 over eight hours. Control patients received an equal volume of saline. Dryness of the operative field, chest drainage, transfusion of HBP, haemoglobin concentrations, and coagulation variables (including bleeding time) were compared. There were no differences between aprotinin and placebo-treated patients for all clinical and laboratory variables. The apparent ineffectiveness of aprotinin may be explained by the use of an insufficient dose, by a different protocol of administration (e.g., no bolus in CPB prime), or by the inability of aprotinin to decrease bleeding and transfusions any further. Also, the number of patients studied does not exclude the possibility of a Type II error. However, based on the small differences observed, we conclude that low-dose aprotinin infusion is not useful clinically to reduce chest drainage and transfusions in a patient population at high risk of being exposed to HBP.RésuméUne posologie élevée d’aprotinine de 5–6 millions KIU diminue le saignement et le besoin de produits sanguins homologues utilisés pour la circulation extracorporelle (CEC). Ces doses élevées visent l’atteinte de concentrations de plasmine et de kallicréine plasmatique efficaces in vitro, mais théoriquement, de plus faibles doses devraient suffire in vivo. De plus, l’aprolinine est une produit coûteux et il est normal qu’on n’utilise que la plus petite dose efficace. C’est dans ce contexte que l’efficacité de l’aprolinine prophylactique 1 million KIU (la dose maximale actuellement approuvée) est évaluée sur une population à haut risque d’hémorragies et de transfusions subséquentes. Quarante-et-un patients soumis à une ré-opération ou à une intervention cardiaque complexe sont inclus dans une étude prospective à double aveugle, randomisée et contrôlée avec placebo. Avant l’incision de la peau, un bolus de 200000 KIU d’aprotinine est administré en 20 min, suivi d’une perfusion de 100 000 KIU · hr−1 répartie sur huit heures. Le groupe contrôle reçoit du soluté physiologique en volume égal. La quantité de sang du champ opératoire, l’importance des pertes par les drains thoraciques, les transfusions de produit sanguins homologues, la concentration de l’hémoglobine et les épreuves de coagulation (temps de saignement inclus) sont comparés. On ne trouve pas de différences entre le groupe aprotinine et le groupe placebo pour tous les paramètres cliniques et de laboratoire. L’inefficacité apparente de l’aprotinine peut s’expliquer par l’utilisation d’une dose insuffisante, par un protocole d’administration différent (v.g. absence de bolus dans l’amorce de CEC), ou par l’incapacité de l’aprotinine à diminuer encore plus le saignement et le besoin de transfusions. De plus le nombre de patients étudiés n’exclut pas la possibilité d’une erreur de type II. Toutefois, sur la base des différences minimes observées, nous concluons que l’aprotinine à faible dose en perfusion n’est pas utile cliniquement pour diminuer les pertes par les drains thoraciques et la quantité de sang transfusée chez une population de patients très susceptible de recevoir des produits de sang homologue.

Reproductibilité et interchangeabilité du Thromboélastographe®, Sonoclot® et du temps de coagulation activé (Hémochron®), en chirurgie cardiaque

PURPOSE Despite their common use in cardiac surgery, few studies have evaluated the reproducibility of the Thromboelastograph (TEG), of the Sonoclot (SCT), and of the activated coagulation time with celite (ACT-C) or kaolin (ACT-K) measured with the Hemochron, in clinical conditions of on-site monitoring of hemostasis. This study determined the reproducibility of those measurements, and evaluated the ability of various devices to substitute for the ACT-C. METHODS Blood samples collected from 20 volunteers and 21 patients undergoing myocardial revascularization were analyzed in the two channels of the TEG, in two SCT and four Hemochron analyzers. The overall of TEG and SCT coagulation profiles were analyzed by a computerized TEG and an experienced observer respectively. The variation rate (V%) was calculated for each variable. The ability of ACT-K and SCT to substitute for ACT-C under different clinical conditions was evaluated. RESULTS ACT-C and ACT-K V% ranged between 5.6% and 10.8% and between 6.7% and 12.4% respectively. TEG and SCT V% ranged between 3.1% and 9.5% and between 5.8% and 33.6% respectively, according to different conditions and parameters. In volunteers and non-heparinized patients, the ACT-C and ACT-K were interchangeable. No other test can substitute for the ACT-C when patients are heparinized during cardiopulmonary bypass (CPB). CONCLUSIONS In the clinical conditions of use, on-site hemostasis monitoring devices providing the most reproducible measurements are, in decreasing order, the TEG, the Hemochron and the SCT. In heparinized patients and during CPB, results from different tests are not interchangeable, stressing the importance of establishing appropriate instrument-specific values for monitoring anticoagulation during cardiac surgery.ObjectifMalgré une utilisation courante, la reproductibilité des mesures du Thromboélastographe® (TEG), du Sonoclot® (SCT), et de l’Hémochron® mesurant le temps de coagulation activé avec célite ou kaolin (ACT-C et ACT-K), a été peu étudiée dans les conditions réelles d’utilisation. La présente étude évalue la reproductibilité de ces mesures, et la possibilité de substituer l’ACT-C par un des autres tests.MéthodeLes échantillons sanguins ont été prélevés chez 20 volontaires et 21 patients devant subir une revascularisation myocardique, et analysés dans deux canaux du TEG, deux SCT et quatre Hémochron®. Les tracés du TEG et du SCT ont été analysés respectivement par ordinateur et par un observateur expérimenté. Le pourcentage de variation (V %) pour chaque variable et l’interchangeabilité de l’ACT-K et du SCT avec l’ACT-C ont été évalués.RésultatsLes V % de l’ACT-C et de l’ACT-K varient respectivement de 5,6 % à 10,8 % et de 6,7 % à 12,4 % selon les conditions. Les V % du TEG et du SCT varient respectivement de 3,1 % à 9,5 % et de 5,8 % à 33,6 %, selon les conditions et les paramètres étudiés. Aucun instrument ne peut se substituer à l’ACT-C en présence d’héparine et durant la circulation extracorporelle (CEC). Chez les volontaires et les malades non héparinisés, l’ACT-C et l’ACT-K sont interchangeables.ConclusionDans des conditions réelles d’utilisation en chirurgie cardiaque, les mesures les plus reproductibles sont obtenues, dans un ordre décroissant, avec le TEG, l’Hémochron puis le SCT Les résultats des différents tests ne sont pas interchangeables chez le malade durant la CEC.AbstractPurposeDespite their common use in cardiac surgery, few studies have evaluated the reproducibility of the Thromboelastograph® (TEG), of the Sonoclot® (SCT), and of the activated coagulation time with celite (ACT-C) or kaolin (ACT-K.) measured with the Hemochron®, in clinical conditions of on-site monitoring of hemostasis. This study determined the reproducibility of those measurements, and evaluated the ability of various devices to substitute for the ACTC.MethodsBlood samples collected from 20 volunteers and 21 patients undergoing myocardial revascularization were analyzed in the two channels of the TEG, in two SCT and four Hemochron® analyzers. The overall of TEG and SCT coagulation profiles were analyzed by a computerized TEG and an experienced observer respectively. The variation rate (V%) was calculated for each variable. The ability of ACT-K and SCT to substitute for ACT-C under different clinical conditions was evaluated.ResultsACT-C and ACT-K V% ranged between 5.6% and 10.8% and between 6.7% and 12.4% respectively. TEG and SCT V% ranged between 3.1 % and 9.5% and between 5.8% and 33.6% respectively, according to different conditions and parameters. In volunteers and nonheparinized patients, the ACT-C and ACT-K were interchangeable. No other test can substitute for the ACT-C when patients are heparinized during cardiopulmonary bypass (CPB).ConclusionsIn the clinical conditions of use, on-site hemostasis monitoring devices providing the most reproducible measurements are, in decreasing order, the TEG, the Hemochron® and the SCT. In heparinized patients and during CPB, results from different tests are not interchangeable, stressing the importance of establishing appropriate instrument-specific values for monitoring anticoagulation during cardiac surgery.

Inotropic support of the heart that fails to successfully wean from cardiopulmonary bypass: The Montreal Heart Institute experience

The selection of an appropriate therapeutic regimen, especially in patients with preexisting cardiac dysfunction prior to surgery, is a crucial element for successful separation from cardiopulmonary bypass (CPB). At the present time there are no definitive studies to determine which treatment modality, or combination of treatments, is optimal in this patient population. A brief review of the literature is presented to answer the following questions: (1) Should inotropic support be administered in anticipation of failure to wean from CPB? and (2) Which inotrope or combination of drugs is best? There is no evidence at present that the prophylactic administration of inotropes to assist separation from CPB may result in damaging effects to the myocardium in humans. Inasmuch as tachycardia is avoided and coronary perfusion pressure is maintained within the normal range, prophylactic inotropes may be of benefit to patients with preexisting myocardial dysfunction during weaning from CPB by allowing a smoother separation and a shorter time on CPB. While no specific drug has been proven superior, the use of phosphodiesterase inhibitors as part of the regimen to provide inotropic support in these patients may exert a beneficial effect on myocardial ischemia and reperfusion injury. Prophylactic support of the circulation during separation from CPB, especially with phosphodiesterase inhibitors, may be indicated in this specific patient population as part of the strategy to ensure maximal preservation of myocardial function.