A Multicenter, Randomized, Double-Blind, Placebo-Controlled Trial of Preoperative Antithrombin Supplementation in Patients at Risk for Antithrombin Deficiency After Cardiac Surgery.

BACKGROUND: Antithrombin (AT) activity is reduced during cardiac operations with cardiopulmonary bypass (CPB), which is associated with adverse outcomes. Preoperative AT supplementation, to achieve >58% and <100% AT activity, may potentially reduce postoperative morbidity and mortality in cardiac operations with CPB. This prospective, multicenter, randomized, double-blind, placebo-controlled study was designed to evaluate the safety and efficacy of preoperative treatment with AT supplementation in patients at risk for low AT activity after undergoing cardiac surgery with CPB. METHODS: A total of 425 adult patients were randomized (1:1) to receive either a single dose of AT (n = 213) to achieve an absolute increase of 20% above pretreatment AT activity or placebo (n = 212) before surgery. The study duration was approximately 7 weeks. The primary efficacy end point was the percentage of patients with any component of a major morbidity composite (postoperative mortality, stroke, acute kidney injury [AKI], surgical reexploration, arterial or venous thromboembolic events, prolonged mechanical ventilation, and infection) in the 2 groups. Secondary end points included AT activity, blood loss, transfusion requirements, duration of intensive care unit (ICU), and hospital stays. Safety was also assessed. RESULTS: Overall, 399 patients (men, n = 300, 75.2%) with a mean (standard deviation [SD]) age of 66.1 (11.7) years, with the majority undergoing complex surgical procedures (n = 266, 67.9%), were analyzed. No differences in the percentage of patients experiencing morbidity composite outcomes between groups were observed (AT-treated 68/198 [34.3%] versus placebo 58/194 [29.9%]; P = .332; relative risk, 1.15). After AT infusion, AT activity was significantly higher in the AT group (108% [42-143]) versus placebo group (76% [40-110]), and lasted up to postoperative day 2. At ICU, the frequency of patients with AT activity ≥58% in the AT group (81.5%) was significantly higher ( P < .001) versus placebo group (43.2%). Secondary end point analysis did not show any advantage of AT over placebo group. There were significantly more patients with AKI ( P < .001) in the AT group (23/198; 11.6%) than in the placebo group (5/194, 2.6%). Safety results showed no differences in treatment-emergent adverse events nor bleeding events between groups. CONCLUSIONS: AT supplementation did not attenuate adverse postoperative outcomes in our cohort of patients undergoing cardiac surgery with CPB.

Interventional vitamin C: A strategy for attenuation of coagulopathy and inflammation in a swine multiple injuries model.

BACKGROUND: Coagulopathy and inflammation induced by hemorrhagic shock and traumatic injury are associated with increased mortality and morbidity. Vitamin C (VitC) is an antioxidant with potential protective effects on the proinflammatory and procoagulant pathways. We hypothesized that high-dose VitC administered as a supplement to fluid resuscitation would attenuate inflammation, coagulation dysfunction, and end-organ tissue damage in a swine model of multiple injuries and hemorrhage. METHODS: Male Sinclair swine (n = 24; mean body weight, 27 kg) were anesthetized, intubated, mechanically ventilated, and instrumented for physiologic monitoring. Following stabilization, swine were subjected to shock/traumatic injury (hypothermia, liver ischemia and reperfusion, comminuted femur fracture, hemorrhagic hypotension), resuscitated with 500 mL of hydroxyethyl starch, and randomized to receive either intravenous normal saline (NS), low-dose VitC (50 mg/kg; LO), or high-dose VitC (200 mg/kg; HI). Hemodynamics, blood chemistry, hematology, and coagulation function (ROTEM) were monitored to 4 hours postresuscitation. Histological and molecular analyses were obtained for liver, kidney, and lung. RESULTS: Compared with VitC animals, NS swine showed significant histological end-organ damage, elevated acute lung injury scores, and increased mRNA expression of tissue proinflammatory mediators (IL-1ß, IL-8, TNFα), plasminogen activation inhibitor-1 and tissue factor. There were no statistically significant differences between treatment groups on mean arterial pressure or univariate measures of coagulation function; however, NS showed impaired multivariate clotting function at 4 hours. CONCLUSION: Although correction of coagulation dysfunction was modest, intravenous high-dose VitC may mitigate the proinflammatory/procoagulant response that contributes to multiple organ failure following acute severe multiple injuries. LEVEL OF EVIDENCE: Prospective randomized controlled blinded trial study, Preclinical (animal-based).

Application of Incident Command Structure to clinical trial management in the academic setting: principles and lessons learned.

BACKGROUND: Clinical trial success depends on appropriate management, but practical guidance to trial organisation and planning is lacking. The Incident Command System (ICS) is the 'gold standard' management system developed for managing diverse operations in major incident and public health arenas. It enables effective and flexible management through integration of personnel, procedures, resources, and communications within a common hierarchical organisational structure. Conventional ICS organisation consists of five function modules: Command, Planning, Operations, Logistics, and Finance/Administration. Large clinical trials will require a separate Regulatory Administrative arm, and an Information arm, consisting of dedicated data management and information technology staff. We applied ICS principles to organisation and management of the Prehospital Use of Plasma in Traumatic Haemorrhage (PUPTH) trial. This trial was a multidepartmental, multiagency, randomised clinical trial investigating prehospital administration of thawed plasma on mortality and coagulation response in severely injured trauma patients. We describe the ICS system as it would apply to large clinical trials in general, and the benefits, barriers, and lessons learned in utilising ICS principles to reorganise and coordinate the PUPTH trial. RESULTS: Without a formal trial management structure, early stages of the trial were characterised by inertia and organisational confusion. Implementing ICS improved organisation, coordination, and communication between multiple agencies and service groups, and greatly streamlined regulatory compliance administration. However, unfamiliarity of clinicians with ICS culture, conflicting resource allocation priorities, and communication bottlenecks were significant barriers. CONCLUSIONS: ICS is a flexible and powerful organisational tool for managing large complex clinical trials. However, for successful implementation the cultural, psychological, and social environment of trial participants must be accounted for, and personnel need to be educated in the basics of ICS. TRIAL REGISTRATION: ClinicalTrials.gov, NCT02303964 . Registered on 28 November 2014.

Hextend-perfluorocarbon cocktail inhibits mean arterial pressure response in a rabbit shock model.

BACKGROUND: Hextend (HEX) is standard of care resuscitation fluid for combat-related traumatic hemorrhage. Because HEX has limited oxygen-carrying capacity, combination therapy with oxygen therapeutics could improve oxygen delivery after hemodynamic shock. We hypothesized that addition of perfluorocarbon (PFC) to HEX would improve hemodynamics and oxygen delivery marker response in a rabbit model of hemorrhagic shock. METHODS: Anesthetized New Zealand rabbits (n = 23) were randomly allocated to resuscitation with fresh whole blood (FWB), HEX, or HEX plus PFC (HEX + PFC) after 60 min of hemorrhagic hypotension. Mean arterial pressure (MAP) was sampled every 2-3 min for 120 min postinfusion; MAP profiles were modeled by a one-compartment pharmacokinetic model to determine peak MAP (Pmax), time to peak MAP (tmax), and postinfusion MAP persistence. Arterial blood was sampled every 15 min to examine pH, blood gases PO2 and pCO2, metabolites lactate and glucose, methemoglobin (metHb), and electrolytes. RESULTS: Compared with FWB and HEX, HEX + PFC administration resulted in delayed peak MAP and less persistent (P < 0.0001) MAP elevation; metHb was significantly elevated (P < 0.0001) compared with FWB and HEX. There were no significant differences in PO2, pCO2, or pH. Glucose, hematocrit, and hemoglobin of both HEX and HEX + PFC were significantly lower relative to FWB. Lactate clearance was modest and transient for all treatments; base deficit was significantly more negative for HEX + PFC. CONCLUSIONS: Addition of PFC to HEX did not improve hemodynamics or acidosis. Further dose- and volume-range studies are required to test efficacy of PFC in combination with HEX for hemorrhagic shock.

A modern literature review of carbon monoxide poisoning theories, therapies, and potential targets for therapy advancement.

The first descriptions of carbon monoxide (CO) and its toxic nature appeared in the literature over 100 years ago in separate publications by Drs. Douglas and Haldane. Both men ascribed the deleterious effects of this newly discovered gas to its strong interaction with hemoglobin. Since then the adverse sequelae of CO poisoning has been almost universally attributed to hypoxic injury secondary to CO occupation of oxygen binding sites on hemoglobin. Despite a mounting body of literature suggesting other mechanisms of injury, this pathophysiology and its associated oxygen centric therapies persists. This review attempts to elucidate the remarkably complex nature of CO as a gasotransmitter. While CO's affinity for hemoglobin remains undisputed, new research suggests that its role in nitric oxide release, reactive oxygen species formation, and its direct action on ion channels is much more significant. In the course of understanding the multifaceted character of this simple molecule it becomes apparent that current oxygen based therapies meant to displace CO from hemoglobin may be insufficient and possibly harmful. Approaching CO as a complex gasotransmitter will help guide understanding of the complex and poorly understood sequelae and illuminate potentials for new treatment modalities.

The use of high-dose hydroxocobalamin for vasoplegic syndrome.

We describe a case of hypotension on cardiopulmonary bypass for coronary artery bypass grafting, double valve repairs, and patent foramen ovale closure. The patient experienced vasoplegic syndrome while on cardiopulmonary bypass. He was treated with high-dose hydroxocobalamin (vitamin B12). His blood pressure responded rapidly, obviating any further vasopressor requirements.

Drug, devices, technologies, and techniques for blood management in minimally invasive and conventional cardiothoracic surgery: a consensus statement from the International Society for Minimally Invasive Cardiothoracic Surgery (ISMICS) 2011.

OBJECTIVE: The objectives of this consensus conference were to evaluate the evidence for the efficacy and safety of perioperative drugs, technologies, and techniques in reducing allogeneic blood transfusion for adults undergoing cardiac surgery and to develop evidence-based recommendations for comprehensive perioperative blood management in cardiac surgery, with emphasis on minimally invasive cardiac surgery. METHODS: The consensus panel short-listed the potential topics for review from a comprehensive list of potential drugs, devices, technologies, and techniques. The process of short-listing was based on the need to prioritize and focus on the areas of highest importance to surgeons, anesthesiologists, perfusionists, hematologists, and allied health care involved in the management of patients who undergo cardiac surgery whether through the conventional or minimally invasive approach. MEDLINE, Cochrane Library, and Embase databases were searched from their date of inception to May 2011, and supplemental hand searches were also performed. Detailed methodology and search strategies are outlined in each of the subsequently published systematic reviews. In general, all relevant synonyms for drugs (antifibrinolytic, aprotinin, [Latin Small Letter Open E]-aminocaproic acid, tranexamic acid [TA], desmopressin, anticoagulants, heparin, antiplatelets, anti-Xa agents, adenosine diphosphate inhibitors, acetylsalicylic acid [ASA], factor VIIa [FVIIa]), technologies (cell salvage, miniaturized cardiopulmonary bypass (CPB) circuits, biocompatible circuits, ultrafiltration), and techniques (transfusion thresholds, minimally invasive cardiac or aortic surgery) were searched and combined with terms for blood, red blood cells, fresh-frozen plasma, platelets, transfusion, and allogeneic exposure. The American Heart Association/American College of Cardiology system was used to label the level of evidence and class of each recommendation. RESULTS AND RECOMMENDATIONS: Database search identified more than 6900 articles, with 4423 full-text randomized controlled trials assessed for eligibility, and the final 125 systematic reviews and meta-analyses were used in the consensus conference. The results of the consensus conference, including the evidence-based statements and the recommendations, are outlined in the text, with references given for the relevant evidence that formed the basis for the statements and recommendations. RECOMMENDATIONS FOR ANTIFIBRINOLYTICS: The lysine analogs ?-aminocaproic acid (Amicar) and tranexamic acid (TA) reduce exposure to allogeneic blood inpatients undergoing on-pump cardiac surgery. These agents are recommended to be used routinely as part of a blood conservation strategy especially in patients at risk of undergoing onpump cardiac surgery (Class I, Level A). It is important not to exceed maximum TA total dosages (50Y100mg/kg) because of potential neurotoxicity in the elderly and open-heart procedures (Class IIb, Level C). Aprotinin is not recommended in adult cardiac surgery until further studies on its safety profile have been performed (Class III, Level A). RECOMMENDATIONS FOR TA IN OFF-PUMP CORONARY ARTERY BYPASS: Tranexamic acid may be recommended as part of a blood conservation strategy in high risk patients undergoing off-pump coronary artery bypass (OPCAB) surgery (Class I, Level A).Tranexamic acid dosing in OPCAB surgery needs further study particularly with regard to possible neurotoxicity such as seizures.In addition, the benefit-risk ratio in OPCAB needs further eludication because of the lower inherent risk for bleeding in this group (Class IIb, Level C). RECOMMENDATIONS FOR DDAVP: DDAVP can be considered for prophylaxis in coronary artery bypass grafting (CABG) surgery, in particular, for patients onASA within 7 days or prolonged CPB more than 140 minutes (Class IIa, Level A). Caution should be used with the DDAVP infusion rate to avoid significant systemic hypotension (Class I, Level A). RECOMMENDATIONS FOR TOPICAL HEMOSTATICS: The routine use of topical antifibrinolytics in cardiac surgery isnot recommended (Class IIa, Level A). Topical fibrin sealants may be considered in clinical situations where conventional approaches of surgical and medical improvement of hemostasis are not effective, that is, with bleeding problems more local than generalized, bearing in mind the blackbox warning of bovine thrombin by the US Food and Drug Administration (Class IIb, Level C).Recommendations for FVIIa:Prophylactic use of FVIIa cannot be recommended because of a significant increase in the risk of thromboembolic events and stroke (Class IIa, Level A).Factor VIIa may be considered in clinical situations where conventional approaches of surgical and pharmacologic hemostasis have failed and uncontrollable hemorrhage poses a high risk of severe and life-threatening outcomes (Class IIb, Level B). RECOMMENDATIONS FOR ERYTHROPOIETIN PLUS IRON: It is reasonable to administer erythropoietin preoperatively to increase red blood cell mass in patients who are anemic or refuse blood products (such as for Jehovah's Witness faith) or who are likely to have postoperative anemia (Class IIa, Level A). RECOMMENDATIONS FOR ANTIPLATELETS BEFORE CARDIAC SURGERY: Acetylsalicylic acid may be continued until surgery (Class IIa,Level B) For stable elective CABG procedures with no drug-elutingstent, stop clopidogrel 5 days before surgery (Class I, Level A).h For stable elective CABG procedures with drug-eluting stents less than 1 year old, consider continuing clopidogrel or heparin as abridge to surgery (Class IIb, Level C).h Direct-acting P2Y12 receptor antagonists may be a better alternative than clopidogrel in acute coronary syndrome patients undergoing CABG surgery (Class IIa, Level B). RECOMMENDATIONS FOR ANTIPLATELETS AFTER CARDIAC SURGERY: In stable CABG surgery (nonYacute coronary syndrome patients), the routine use of postoperative clopidogrel with ASAis not warranted (Class IIb, Level B). RECOMMENDATIONS FOR ACUTE NORMOVOLEMIC HEMODILUTION: Acute normovolemic hemodilution can be considered in selected patients with adequate preoperative hemoglobin to reduce post-CPB bleeding (Class IIa, Level A).The routine use of acute normovolemic hemodilution is not recommended (Class IIb, Level B). RECOMMENDATIONS FOR RETROGRADE AUTOLOGOUS PRIMING: Retrograde autologous priming is recommended as a blood conservation modality to reduce allogeneic blood transfusion for onpump cardiac surgery (Class I, Level A). RECOMMENDATIONS FOR CELL SALVAGE: Routine use of cell salvage is recommended in operations where an increased blood loss is expected (Class 1, Level A). Cell salvage should be used throughout the entire operation and not merely as a replacement for CPB cardiotomy suction (Class IIa, Level A). RECOMMENDATIONS: BIOCOMPATIBLE CPB CIRCUITS: The routine use of biocompatible coated CPB circuitry may be considered as part of a multimodal blood conservation program. However, the heterogeneity of surface-modified products, anticoagulation management, and CPB technique does not significantly impact surgical blood loss and transfusion needs (Class IIb,Level A). RECOMMENDATIONS FOR MINIATURIZED EXTRACORPOREAL CARDIOPULMONARY CIRCUIT VERSUS CONVENTIONAL EXTRACORPOREAL CARDIOPULMONARY CIRCUIT: Miniaturized extracorporeal cardiopulmonary circuit can be considered as a blood conservation technique to reduce allogeneic blood exposure (Class IIa, Level A); however, issues related to heparinization management and biocompatible coatings remain to be clarified. RECOMMENDATIONS FOR ULTRAFILTRATION (CONTINUOUS OR MODIFIED):h Ultrafiltration may be considered for blood conservation (Class IIb, Level A); however, the impact on clinically relevant outcomes remains unknown. RECOMMENDATIONS FOR PLATELET PLASMAPHERESIS:It is reasonable to recommend platelet plasmapheresis for blood management in cardiac surgery (Class IIa, Level A), although the impact on clinically relevant outcomes remains unknown. RECOMMENDATIONS FOR POINT-OF-CARE MONITORING:The evidence is too premature to recommend point-of-caretechnology for routine use because its use has not been shown to impact clinical outcome (Class IIb, Level A). RECOMMENDATIONS FOR SURGICAL TECHNIQUES FOR OPCAB, MINIMALLY INVASIVE STERNOTOMY FOR AORTIC VALVE SURGERY, MINIMALLY INVASIVE STERNOTOMY FOR MITRAL VALVE SURGERY, AND TRANSCATHETHER AORTIC VALVE IMPLANTATION: Although these minimally invasive procedures are not primarily selected for the purpose of blood management, the reduced allogeneic blood exposure should be considered in the balance of benefits and risks when selecting the appropriate surgery for patients.

Perfluorocarbon emulsions as a promising technology: a review of tissue and vascular gas dynamics.

Perfluorocarbon (PFC) emulsions are halogen-substituted carbon nonpolar oils with resultant enhanced dissolved respiratory gas (O(2), N(2), CO(2), nitric oxide) capabilities. In the first demonstration of enhanced O(2) solubility, inhaled PFC could sustain rat metabolism. Intravenous emulsions were then trialed as "blood substitutes." In the last 10 yr, biocomputational modeling has enhanced our mechanistic understanding of PFCs. Contemporary research is now taking advantage of these physiological discoveries and applying PFCs as "oxygen therapeutics," as well as ways to enhance other gas movements. One particularly promising area of research is the treatment of gas embolism (arterial and venous emboli/decompression sickness). An expansive understanding of PFC-enhanced diffusive gas movements through tissue and vasculature may have analogous applications for O(2) or other respiratory gases and should provide a revolution in medicine. This review will stress the fundamental knowledge we now have regarding how respiratory gas movements are changed when intravenous PFC is present.

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

BACKGROUND: A minority of patients having cardiac procedures (15% to 20%) consume more than 80% of the blood products transfused at operation. Blood must be viewed as a scarce resource that carries risks and benefits. A careful review of available evidence can provide guidelines to allocate this valuable resource and improve patient outcomes. METHODS: We reviewed all available published evidence related to blood conservation during cardiac operations, including randomized controlled trials, published observational information, and case reports. Conventional methods identified the level of evidence available for each of the blood conservation interventions. After considering the level of evidence, recommendations were made regarding each intervention using the American Heart Association/American College of Cardiology classification scheme. RESULTS: Review of published reports identified a high-risk profile associated with increased postoperative blood transfusion. Six variables stand out as important indicators of risk: (1) advanced age, (2) low preoperative red blood cell volume (preoperative anemia or small body size), (3) preoperative antiplatelet or antithrombotic drugs, (4) reoperative or complex procedures, (5) emergency operations, and (6) noncardiac patient comorbidities. Careful review revealed preoperative and perioperative interventions that are likely to reduce bleeding and postoperative blood transfusion. Preoperative interventions that are likely to reduce blood transfusion include identification of high-risk patients who should receive all available preoperative and perioperative blood conservation interventions and limitation of antithrombotic drugs. Perioperative blood conservation interventions include use of antifibrinolytic drugs, selective use of off-pump coronary artery bypass graft surgery, routine use of a cell-saving device, and implementation of appropriate transfusion indications. An important intervention is application of a multimodality blood conservation program that is institution based, accepted by all health care providers, and that involves well thought out transfusion algorithms to guide transfusion decisions. CONCLUSIONS: Based on available evidence, institution-specific protocols should screen for high-risk patients, as blood conservation interventions are likely to be most productive for this high-risk subset. Available evidence-based blood conservation techniques include (1) drugs that increase preoperative blood volume (eg, erythropoietin) or decrease postoperative bleeding (eg, antifibrinolytics), (2) devices that conserve blood (eg, intraoperative blood salvage and blood sparing interventions), (3) interventions that protect the patient's own blood from the stress of operation (eg, autologous predonation and normovolemic hemodilution), (4) consensus, institution-specific blood transfusion algorithms supplemented with point-of-care testing, and most importantly, (5) a multimodality approach to blood conservation combining all of the above.

Bivalirudin anticoagulation for a patient with hypercoagulable immune syndromes undergoing mitral valve surgery.

Unfractionated heparin has been a near universal anticoagulant for cardiac surgery; however it is contraindicated in heparin-induced thrombocytopenia type II. Alternative anticoagulants such as bivalirudin (a direct thrombin inhibitor) are being utilized. Bivalirudin was successfully used in an immunologically complex patient (diagnoses of heparin-induced thrombocytopenia type II, systemic lupus erythematosus, antiphospholipid syndrome, and dialysis-dependent renal failure) requiring cardiopulmonary bypass. Thrombotic events are common in antiphospholipid syndrome patients undergoing cardiac surgery utilizing high-dose heparin. This may represent unrecognized heparin-induced thrombocytopenia type II. Our patient did not experience perioperative thrombotic or bleeding complications. The possible cross-reactivity between heparin induced thrombocytopenia type II and antiphospholipid syndrome has not been investigated.

Current status of antifibrinolytics in cardiopulmonary bypass and elective deep hypothermic circulatory arrest.

Cardiopulmonary bypass (CPB) results in many physiologic derangements, including activation of the hemostatic and fibrinolytic pathways. Deep hypothermic circulatory arrest (DHCA) adds a further insult to the coagulation systems because it involves more extreme hypothermia and organ ischemia related to blood stasis. The abnormalities induced by CPB disrupt the checks and balances in the hemostatic and fibrinolytic systems, resulting in a pathologic state that leads to excessive bleeding and other perioperative complications. Prophylactic antifibrinolytic therapy can attenuate the response to this insult by restoring the delicate balance within these systems, potentially reducing the complication rate and improving patient outcomes.