Linda Shore-Lesserson

2011 Update to The Society of Thoracic Surgeons and the Society of Cardiovascular Anesthesiologists Blood Conservation Clinical Practice Guidelines

BACKGROUNDnPractice guidelines reflect published literature. Because of the ever changing literature base, it is necessary to update and revise guideline recommendations from time to time. The Society of Thoracic Surgeons recommends review and possible update of previously published guidelines at least every three years. This summary is an update of the blood conservation guideline published in 2007.nnnMETHODSnThe search methods used in the current version differ compared to the previously published guideline. Literature searches were conducted using standardized MeSH terms from the National Library of Medicine PUBMED database list of search terms. The following terms comprised the standard baseline search terms for all topics and were connected with the logical OR connector--Extracorporeal circulation (MeSH number E04.292), cardiovascular surgical procedures (MeSH number E04.100), and vascular diseases (MeSH number C14.907). Use of these broad search terms allowed specific topics to be added to the search with the logical AND connector.nnnRESULTSnIn this 2011 guideline update, areas of major revision include: 1) management of dual anti-platelet therapy before operation, 2) use of drugs that augment red blood cell volume or limit blood loss, 3) use of blood derivatives including fresh frozen plasma, Factor XIII, leukoreduced red blood cells, platelet plasmapheresis, recombinant Factor VII, antithrombin III, and Factor IX concentrates, 4) changes in management of blood salvage, 5) use of minimally invasive procedures to limit perioperative bleeding and blood transfusion, 6) recommendations for blood conservation related to extracorporeal membrane oxygenation and cardiopulmonary perfusion, 7) use of topical hemostatic agents, and 8) new insights into the value of team interventions in blood management.nnnCONCLUSIONSnMuch has changed since the previously published 2007 STS blood management guidelines and this document contains new and revised recommendations.

Universal definition of perioperative bleeding in adult cardiac surgery

OBJECTIVESnPerioperative bleeding is common among patients undergoing cardiac surgery; however, the definition of perioperative bleeding is variable and lacks standardization. We propose a universal definition for perioperative bleeding (UDPB) in adult cardiac surgery in an attempt to precisely describe and quantify bleeding and to facilitate future investigation into this difficult clinical problem.nnnMETHODSnThe multidisciplinary International Initiative on Haemostasis Management in Cardiac Surgery identified a common definition of perioperative bleeding as an unmet need. The functionality and usefulness of the UDPB for clinical research was then tested using a large single-center, nonselected, cardiac surgical database.nnnRESULTSnA multistaged definition for perioperative bleeding was created based on easily measured clinical end points, including total blood loss from chest tubes within 12 hours, allogeneic blood products transfused, surgical reexploration including cardiac tamponade, delayed sternal closure, and the need for salvage treatment. Depending on these components, bleeding is graded as insignificant, mild, moderate, severe, or massive. When applied to an established cardiac surgery dataset, the UDPB provided insight into the incidence and outcome of bleeding after cardiac surgery.nnnCONCLUSIONSnThe proposed UDPB in adult cardiac surgery provides a precise classification of bleeding that is useful in everyday practice as well as in clinical research. Once fully validated, the UDPB may be useful as an institutional quality measure and serve as an important end point in future cardiac surgical research.

Clevidipine in adult cardiac surgical patients: A dose-finding study

Background Treatment of elevated blood pressure is frequently necessary after cardiac surgery to minimize postoperative bleeding and to attenuate afterload changes associated with hypertension. The purpose of this study was to investigate the pharmacodynamics and pharmacokinetics of a short-acting calcium channel antagonist, clevidipine, in the treatment of hypertension in postoperative cardiac surgical patients. Methods Postoperative cardiac surgical patients were randomized to receive placebo or one of six doses of clevidipine. Hemodynamic parameters were recorded and blood samples were drawn for determination of clevidipine plasma concentrations during infusion and after discontinuation of clevidipine. The concentration–response relation was analyzed using logistic regression, and pharmacokinetic models were applied to the data using population analysis. Results There were significant decreases in mean arterial blood pressure and systemic vascular resistance at doses greater than or equal to 1.37 &mgr;g · kg−1 · min−1. There were no changes in heart rate, central venous pressure, pulmonary artery occlusion pressure, or cardiac index with increasing doses of clevidipine. The clevidipine C50 value for a 10% or greater decrease in mean arterial pressure was 9.7 &mgr;g/l and for a 20% or greater decrease in mean arterial pressure was 26.3 &mgr;g/l. The pharmacokinetics of clevidipine were best described with a three-compartment model with a volume of distribution of 32.4 l and clearance of 4.3 l/min. The early phase of drug disposition had a half-life of 0.6 min. The context-sensitive half-time is less than 2 min for up to 12 h of administration. Conclusion Clevidipine is a calcium channel antagonist with a very short duration of action that effectively decreases systemic vascular resistance and mean arterial pressure without changing heart rate, cardiac index, or cardiac filling pressures.

Patient blood management during cardiac surgery: Do we have enough evidence for clinical practice?

Transfusion of allogeneic blood products during and aftercardiac operations is common. When the degree of ane-mia and the consequent decrease in oxygen deliverylead to organ ischemia, there is little doubt that red bloodcell (RBC) transfusion is necessary. In addition, treat-ment with fresh-frozen plasma and platelets may be nec-essary to support coagulation. Treatment with bloodproducts may also aim to prevent hemodynamic instabil-ity from excessive postoperative blood loss. A large bodyof evidence, however, indicates that transfusion of bloodproducts per se may be associated with increased morbid-ity and mortality after cardiac operations.

Timing and Incidence of Postoperative Infections Associated with Blood Transfusion: Analysis of 1,489 Orthopedic and Cardiac Surgery Patients

BACKGROUNDnTransfusion rates remain high in cardiac and orthopedic surgery and differ widely across physician practices in spite of growing knowledge that allogeneic blood transfusion (ABT) is associated with a risk of postoperative infection.nnnMETHODSnThis prospective observational study compared the timing and incidence of ABT-associated postoperative infections (PIs) in 1,489 orthopedic or cardiac surgery patients at nine hospitals.nnnRESULTSnOf 455 cardiovascular and 1,034 orthopedic surgery patients, 415 (55.6% of the cardiovascular patients and 15.7% of the orthopedic patients) were given ABT. The overall rate of PI during hospitalization was 5.8%. The relative risk of PI was 3.6-fold greater after ABT (50 patients; 12.1%) than in patients not having ABT (36 patients; 3.4%; 95% confidence interval 2.4, 5.4; p = 0.001). Postoperative infections appeared both during hospitalization (n = 86) and within four weeks after discharge (n = 81).nnnCONCLUSIONSnPatients should be followed for as long as four weeks after discharge to determine the true incidence and risk of ABT-associated PI.

An investigation of a new activated clotting time "MAX-ACT" in patients undergoing extracorporeal circulation

Activated clotting time (ACT) is a test used in the operating room for monitoring heparin effect. However, ACT does not correlate with heparin levels because of its lack of specificity for heparin and its variability during hypothermia and hemodilution on cardiopulmonary bypass (CPB). A modified ACT using maximal activation of Factor XII, MAX-ACT (Actalyke MAX-ACT; Array Medical, Somerville, NJ), may be less variable and more closely related to heparin levels. We compared MAX-ACT with ACT in 27 patients undergoing CPB. We measured ACT, MAX-ACT, temperature, and hematocrit at six time points: baseline; postheparin; on CPB 30, 60, and 90 min; and postprotamine. Additionally, we assessed anti-Factor Xa heparin activity and antithrombin III activity at four of these six time points. With institution of CPB and hemodilution, MAX-ACT and ACT did not change significantly but had a tendency to increase, whereas concomitant heparin levels decreased (P = 0.065). Neither test correlated with heparin levels. ACT and MAX-ACT did not differ during normothermia but did during hypothermia, and ACT was significantly longer than MAX-ACT (P = 0.009). At the postheparin time point, ACT-heparin sensitivity (defined as [ACT postheparin − ACT baseline]/[heparin concentration postheparin − heparin concentration baseline]) was greater than MAX-ACT-heparin sensitivity (analogous calculation for MAX-ACT; 520 [266 − 9366] s · U−1 · mL−1 vs 468 [203 − 8833] s · U−1 · mL−1;P = 0.022).

The Society of Thoracic Surgeons, The Society of Cardiovascular Anesthesiologists, and The American Society of ExtraCorporeal Technology: Clinical Practice Guidelines for Cardiopulmonary Bypass—Temperature Management During Cardiopulmonary Bypass

In order to improve our understanding of the evidence-based literature supporting temperature management during adult cardiopulmonary bypass, The Society of Thoracic Surgeons, the Society of Cardiovascular Anesthesiology and the American Society of ExtraCorporeal Technology tasked the authors to conduct a review of the peer-reviewed literature, including: 1) optimal site for temperature monitoring, 2) avoidance of hyperthermia, 3) peak cooling temperature gradient and cooling rate, and 4) peak warming temperature gradient and rewarming rate. Authors adopted the American College of Cardiology/American Heart Association method for development clinical practice guidelines, and arrived at the following recommendations: No Recommendation No recommendation for a guideline is provided concerning optimal temperature for weaning from CPB due to insufficient published evidence.

Anticoagulation management during cardiopulmonary bypass: A survey of 54 North American institutions

FIGURE 1. Target activated clotting time (ACT) before instituting cardiopulmonary bypass (CPB). The x-axis shows the value for target ACT before Despite evidence-based guidelines for blood conservation in cardiac surgery, the clinical management of anticoagulation during cardiopulmonary bypass (CPB) is not standardized. This is further complicated by the fact that patients’ responsiveness to heparin is variable. Impaired heparin responsiveness or ‘‘heparin resistance’’ is often the result of patient-specific causes, such as antithrombin deficiency or high concentrations of heparin-binding proteins, but can also be due to the heparin formulation itself. In clinical practice inhibiting thrombin formation/activity during CPB is essential to minimizing overt thrombosis, the clinical consequences of a consumptive coagulopathy, or both. A survey of anticoagulation practices, published in 1999, observed significant variability in practice with reported acceptable activated clotting times (ACTs) ranging from 240 to 1000 seconds. The purpose of the present analysis a decade later is to characterize current anticoagulation management strategies for CPB. instituting CPB, and the y-axis shows the percentage of sites reporting that particular target value.

Thromboelastograph with platelet mappingTM predicts postoperative chest tube drainage in patients undergoing coronary artery bypass grafting

OBJECTIVEnThe goal of this study was to evaluate the ability of Thromboelastograph with Platelet Mapping (TEG-PM(TM)) to predict postoperative bleeding tendency in patients with a history of recent anti-platelet therapy undergoing coronary artery bypass grafting (CABG).nnnDESIGNnA retrospective analysis. Association between predictor variables (MAADP [maximum amplitude produced by adenosine diphosphate], MAAA [maximum amplitude produced by arachidonic acid], percent of platelets inhibited by clopidogrel, percent of platelets inhibited by aspirin) and the outcomes as elevated chest tube drainage (CTD) and blood transfusion were investigated by logistic regression model. CTD was considered elevated if it was ≥ 600 mL within 12 hours after surgery.nnnSETTINGnA university hospital.nnnPARTICIPANTSnPatients on antiplatelet therapy scheduled to undergo CABG that had TEG-PM(TM) done as a point-of-care test.nnnINTERVENTIONSnNone.nnnRESULTSnA total of 78 patients had preoperative TEG-PM(TM) test and on-pump CABG surgeries performed on the same day. Among them, 20 patients (25.6%) had elevated CTD. Decreased MAADP (odds ratio [OR] 0.94), increased percent inhibition of platelets by clopidogrel (OR 1.03), and lower body mass index (BMI) (OR 0.78) were significantly associated with elevated CTD. The same parameters were also associated with platelets transfusion: MAADP (OR 0.94), percent of inhibition of platelets by clopidogrel (OR 1.03) and BMI (OR 0.77).nnnCONCLUSIONSnTEG-PM(TM) parameters and BMI are predictive of elevated CTD and platelets transfusion. A 1 mm decrease in MAADP increases the likelihood of elevated CTD and the likelihood of platelets transfusion by 6% whereas 1 unit decrease in BMI is associated with an increased likelihood of elevated CTD and platelets transfusion by 22% and 23% respectively.

The balance of concurrent aggregation and deaggregation processes in platelets is linked to differential occupancy of ADP receptor subtypes.

Deaggregation, the partial reversal of the initial aggregation of platelets is observed following low, but not higher, micromolar ADP concentrations. This study tested the hypothesis that deaggregation results from a balance between concurrent, opposing, aggregation and deaggregation processes which are ADP (adenosine 5-diphosphate) receptor occupancy-dependent. Aggregation of human platelet-rich plasma (PRP) prepared in r-hirudin was assayed in a 96-well plate reader over 20 min by measurement of the optical density (OD) at 580 nm. Aggregation and the time to reach peak aggregation were directly proportional to ADP receptor occupancy. The magnitude and time course of the response to ADP were comparable to those previously reported with standard aggregometry. The rate constant of platelet deaggregation, as assessed by a fourcompartment kinetic model, was inversely proportional to agonist concentration. The ratio of the rate constants of aggregation and deaggregation was receptor occupancy-dependent and directly proportional to aggregation. Consequently, platelet aggregation was proportional, and deaggregation inversely proportional, to ADP receptor occupancy. We propose that the response of PRP to ADP and to 2-MeS-ADP (2-methylthioadenosinediphosphate), in vitro , consists of at least two active, concurrent processes, aggregation and deaggregation. Incremental occupancy of the P 2T ADP receptor subtype attenuates deaggregation and governs the balance between these two processes.