RESUMO
OBJECTIVES: We sought to evaluate the efficacy of recombinant human antithrombin III for restoration of heparin responsiveness in heparin-resistant patients scheduled for cardiac surgery. METHODS: This was a multicenter, randomized, double-blind, placebo-controlled study in heparin-resistant patients undergoing elective cardiac surgery. Patients were considered heparin resistant if the activated clotting time was less than 480 seconds after 400 U/kg heparin. Fifty-two heparin-resistant patients were randomized into 2 cohorts. One cohort received a single bolus (75 U/kg) of recombinant human antithrombin III (n = 28), and the other, the placebo group (n = 24), received a normal saline bolus. If the activated clotting time remained less than 480 seconds, this was defined as treatment failure, and 2 units of fresh frozen plasma were transfused. Patients were monitored for adverse events during hospitalization. RESULTS: Six (21%) of the patients in the recombinant human antithrombin III group received fresh frozen plasma transfusions compared with 22 (92%) of the placebo-treated patients ( P < .001). Two units of fresh frozen plasma did not restore heparin responsiveness. There was no increased incidence of adverse events associated with recombinant human antithrombin III administration. Postoperative 24-hour chest tube bleeding was not different in the 2 groups. Surrogate measures of hemostatic activation suggested that there was less activation of the hemostatic system during cardiopulmonary bypass in the recombinant human antithrombin III group. CONCLUSION: Treatment with recombinant human antithrombin III in a dose of 75 U/kg is effective in restoring heparin responsiveness and promoting therapeutic anticoagulation for cardiopulmonary bypass in the majority of heparin-resistant patients. Two units of fresh frozen plasma were insufficient to restore heparin responsiveness. There was no apparent increase in bleeding associated with recombinant human antithrombin III.
Assuntos
Antitrombina III/administração & dosagem , Fibrinolíticos/uso terapêutico , Heparina/uso terapêutico , Adulto , Idoso , Coagulação Sanguínea/fisiologia , Ponte Cardiopulmonar , Ponte de Artéria Coronária , Método Duplo-Cego , Resistência a Medicamentos , Hemostasia Cirúrgica , Humanos , Pessoa de Meia-Idade , Peptídeo Hidrolases/sangue , Proteínas Recombinantes/uso terapêutico , Tempo de Coagulação do Sangue TotalRESUMO
This study was designed to determine whether the maintenance of higher than usual patient-specific heparin concentrations during cardiopulmonary bypass (CPB) was associated with more effective suppression of hemostasis system activation. Thirty-one patients scheduled for repeat cardiac surgery or combined procedures (i.e., coronary revascularization + valve repair/replacement) were consented and enrolled in this study. All patients received porcine heparin and protamine and were randomly assigned to monitoring of anticoagulation by either celite ACT alone (Control, n = 16) or by kaolin ACT combined with on-site measurements of whole blood heparin concentration (Intervention, n = 15). Blood specimens collected before administration of heparin, before weaning from CPB and after administration of protamine were analyzed with a battery of coagulation assays. Patients in the intervention cohort received appreciably greater heparin doses than control patients, resulting in higher anti-Xa heparin levels at the end of CPB. Fibrinopeptide A and D-dimer levels were higher in the control group before discontinuation of CPB. Percent decrease during CPB were greater in the control group for factors V and VIII, fibrinogen and antithrombin III. Percent decrease in complement 3 was greater in the control group after protamine and bleeding times measured in the Intensive Care Unit were significantly more prolonged in this group. Maintenance of higher patient-specific heparin concentrations during CPB more effectively suppresses excessive hemostatic system activation than do standard heparin doses chosen based on measurement of ACT. These findings may explain, at least in part, the significant reduction in perioperative blood loss and blood product use when higher heparin concentrations are maintained.
Assuntos
Coagulação Sanguínea/efeitos dos fármacos , Procedimentos Cirúrgicos Cardíacos , Heparina/sangue , Complicações Intraoperatórias/prevenção & controle , Idoso , Feminino , Heparina/administração & dosagem , Humanos , Masculino , Pessoa de Meia-Idade , Tempo de Coagulação do Sangue TotalRESUMO
Spinal cord ischemia with resultant paraplegia or paraparesis remains an important clinical problem after operations on the thoracoabdominal aorta. Because hypothermia has a protective effect on ischemic neural tissue, we developed a baboon model of spinal cord ischemia to simulate the situation encountered clinically for resection of aneurysms of the thoracoabdominal aorta and to determine whether profound hypothermia produced by hypothermic cardiopulmonary bypass has a protective effect on spinal cord function. After cardiopulmonary bypass was established, the aorta was clamped distal to the left subclavian artery and proximal to the renal arteries for 60 minutes. Group I animals (n = 9) underwent aortic clamping at normothermia (37 degrees C), and group II animals (n = 9) were cooled to a rectal temperature of 15 degrees C before aortic clamping and underwent cardiopulmonary bypass at this temperature until the aorta was unclamped. Of the eight operative survivors in group I, six animals were paraplegic and two were paraparetic, whereas all six group II animals that survived the procedure were neurologically intact (p = 0.0002). The protective effect of hypothermia was associated with blunting of the hyperemic response of spinal cord blood flow (determined by the radioactive microsphere technique) in the lower thoracic and the lumbar segments of the spinal cord after unclamping of the aorta. Profound hypothermia produced by hypothermic cardiopulmonary bypass may be an effective method of protection of the spinal cord in patients undergoing repair of aneurysms of the thoracoabdominal aorta and may reduce the prevalence of ischemic injury to the spinal cord.
Assuntos
Ponte Cardiopulmonar , Hipotermia Induzida , Isquemia/prevenção & controle , Medula Espinal/irrigação sanguínea , Animais , Modelos Animais de Doenças , Hemodinâmica , Masculino , Papio , Paraplegia/fisiopatologia , Fluxo Sanguíneo Regional , Medula Espinal/fisiologiaRESUMO
Previous reports suggest that activated clotting times do not correlate with heparin concentration during cardiopulmonary bypass. This study was designed to compare whole blood heparin concentration and activated clotting time measurements with laboratory-based plasma heparin concentration. Sixty-two patients having cardiac operations requiring cardiopulmonary bypass were enrolled in this study. The study was conducted in two phases. In phase I of this trial, blood specimens were obtained from 30 patients before heparin administration and after each of three heparin doses (20, 80, and 150 U/kg). In phase II, blood specimens were obtained from 32 patients before heparin administration and 10 minutes after each of the following: heparin administration (250 or 300 U/kg), initiation of cardiopulmonary bypass, achievement of hypothermia, initiation of rewarming, and immediately before discontinuation of bypass. Blood specimens were used to measure activated clotting time (kaolin and celite), whole blood heparin concentration, and anti-factor Xa plasma heparin concentration. In phase I, activated clotting time (celite: r = 0.91; kaolin: r = 0.93) and whole blood heparin concentration (r = 0.98) measurements correlated well with plasma heparin concentration. After initiation of cardiopulmonary bypass (phase II), weak correlations for activated clotting time measurements (celite: r = 0.34; kaolin: r = 0.59) and a strong correlation for whole blood heparin concentration (r = 0.95) were evident when compared with plasma heparin concentration. During bypass, activated clotting time measurements also inversely correlated with temperature (celite: r = -0.21; kaolin: r = -0.19) and hematocrit (celite: r = -0.26; kaolin: r = -0.21). A weak correlation between activated clotting time measurements and plasma heparin concentration is evident during the cardiopulmonary bypass period, probably because of the influence of both reduced hematocrit and temperature on the activated clotting time assay. In contrast, whole blood heparin measurements correlate well with plasma heparin concentration before and during bypass. Further studies are needed to determine whether maintaining heparin levels during cardiopulmonary bypass by monitoring heparin concentration is more effective in preventing consumptive activation of the hemostatic system, reducing bleeding, and minimizing the use of blood products after cardiopulmonary bypass when compared with a protocol based on activated clotting time.
Assuntos
Coagulação Sanguínea , Procedimentos Cirúrgicos Cardíacos , Inibidores do Fator Xa , Heparina/sangue , Coagulação Sanguínea/efeitos dos fármacos , Ponte Cardiopulmonar , Relação Dose-Resposta a Droga , Procedimentos Cirúrgicos Eletivos , Hematócrito , Heparina/administração & dosagem , Humanos , Temperatura , Fatores de Tempo , Tempo de Coagulação do Sangue TotalRESUMO
Although laboratory coagulation tests permit a rational approach to both diagnosis and management of coagulation disorders after cardiopulmonary bypass, their clinical utility is limited by delays in obtaining results. This study was designed to evaluate prospectively the impact of on-site coagulation testing on blood product use, operative time, and intraoperative management of microvascular bleeding. Patients who underwent cardiac procedures involving cardiopulmonary bypass and subsequently developed microvascular bleeding were randomly assigned to receive either standard therapy (n = 36) or therapy defined by a treatment algorithm based on results from an on-site coagulation monitoring laboratory (n = 30). No differences were found between treatment groups in hematologic assay data, operative procedures, or duration of cardiopulmonary bypass. Patients treated in accordance with on-site laboratory results (algorithm therapy) received significantly less intraoperative fresh frozen plasma (0.4 +/- 1.1 U versus 2.4 +/- 2.8 U; p = 0.0006) during the treatment interval, had shorter operative times, and had less mediastinal chest tube drainage during the initial perioperative interval (158 +/- 169 ml versus 326 +/- 258 ml; p = 0.003) than did patients in the standard therapy group. Patients who underwent algorithm therapy also received fewer platelet (1.6 +/- 5.9 versus 6.4 +/- 8.2 U; p = 0.02) and red blood cell (1.9 +/- 1.7 U versus 4.1 +/- 4.1 U; p = 0.01) transfusions after the operation. Nine of 36 (25%) standard group patients received initial therapy which differed from that which would have been guided by the on-site algorithm protocol. Our findings indicate that rapid and accurate coagulation test results can guide specific therapy and optimize treatment of microvascular bleeding in patients who undergo cardiac operations.
Assuntos
Testes de Coagulação Sanguínea , Procedimentos Cirúrgicos Cardíacos , Monitorização Intraoperatória , Transfusão de Sangue , Protocolos Clínicos , Desamino Arginina Vasopressina/administração & dosagem , Feminino , Hemorragia/diagnóstico , Hemorragia/terapia , Hemostasia Cirúrgica , Humanos , Complicações Intraoperatórias/diagnóstico , Complicações Intraoperatórias/terapia , Masculino , Microcirculação , Plasma , Transfusão de Plaquetas , Estudos Prospectivos , Protaminas/administração & dosagemRESUMO
A whole blood hemostasis system (Hepcon) provides both activated clotting time and accurate whole blood heparin concentration measurements via an automated protamine titration method. This study was designed to prospectively evaluate the impact of heparin and protamine administration using this system on the incidence and treatment of bleeding after cardiopulmonary bypass. Two hundred fifty-four patients requiring cardiopulmonary bypass were enrolled in this prospective study over a 7-month period. Patients treated with antifibrinolytic agents (aprotinin, epsilon-aminocaproic or tranexamic acid) were excluded. Patients were randomly assigned to either a control (n = 127) or intervention (n = 127) group. For control patients, the anticoagulation protocol consisted of an initial fixed dose of 250 U/kg of heparin, and additional 5000 U heparin doses were administered if the activated clotting time was less than 480 seconds. Heparin was neutralized with an initial fixed dose of protamine (0.8 mg protamine per milligram total heparin). For the intervention group, an initial dose of heparin was based on an automated heparin dose-response assay. Additional heparin doses were administered if the heparin concentration was less than the reference concentration or for an activated clotting time less than 480 seconds. The protamine dose was based on the residual heparin concentration. Treatment of excessive bleeding after cardiopulmonary bypass was based on an algorithm using point-of-care testing with whole blood prothrombin time, activated partial thromboplastin time, heparinase activated clotting time, and platelet count. No differences between the two treatment groups were identified in reference to demographic factors, preoperative anticoagulant medications, preoperative coagulation data, number of reoperations, or combined procedures and duration of cardiopulmonary bypass. Indirect evidence for coagulation factor consumption was demonstrated in control patients by more prolonged whole blood prothrombin time and activated partial thromboplastin time values after cardiopulmonary bypass when compared with values obtained in the intervention group. Patients in the intervention cohort received greater doses of heparin (intervention: 612 +/- 147, control: 462 +/- 114 U/kg, p < 0.0001) and had lower protamine to heparin ratios (intervention: 0.70 +/- 0.64, control: 0.94 +/- 0.21, p = 0.0001) compared with control patients. Patients in the intervention cohort received significantly fewer platelet (intervention: 1.7 +/- 3.6 U, control: 3.7 +/- 6.7 U, p = 0.003), plasma (intervention: 0.4 +/- 1.3 U, control: 1.4 +/- 2.5 U, p = 0.0001), and cryoprecipitate units (intervention: 0.0 +/- 0.0 U, control: 0.2 +/- 1.2 U, p = 0.04) during the perioperative interval than control patients.(ABSTRACT TRUNCATED AT 400 WORDS)
Assuntos
Perda Sanguínea Cirúrgica/prevenção & controle , Ponte Cardiopulmonar/métodos , Heparina/administração & dosagem , Heparina/sangue , Monitorização Fisiológica/instrumentação , Protaminas/administração & dosagem , Idoso , Testes de Coagulação Sanguínea/instrumentação , Transfusão de Sangue/estatística & dados numéricos , Distribuição de Qui-Quadrado , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Estudos Prospectivos , Protaminas/análise , Tempo de Coagulação do Sangue TotalRESUMO
Patients undergoing cardiac surgery with cardiopulmonary bypass are at increased risk for microvascular bleeding that requires perioperative transfusion of blood components. Platelet-related defects have been shown to be the most important hemostatic abnormality in this setting. The exact association between preoperative use of potent platelet inhibitors and either bleeding or transfusion in patients undergoing cardiac surgical procedures is currently being defined. Laboratory evaluation of platelets and coagulation factors can facilitate the optimal administration of pharmacologic and transfusion-based therapy. However, their turnaround time makes laboratory-based methods impractical for concurrent management of surgical patients, which has led many investigators to study the role of point-of-care coagulation tests in this setting. Use of point-of-care tests of hemostatic function can optimize the management of excessive bleeding and reduce transfusion. Accordingly, point-of-care tests that assess platelet function may also identify patients at risk for acquired, platelet-related bleeding. The ability to reduce the unnecessary use of blood products and to decrease operative time or reexploration rates has important consequences for blood inventory, blood costs, and overall health care costs.
Assuntos
Perda Sanguínea Cirúrgica/prevenção & controle , Plaquetas/fisiologia , Procedimentos Cirúrgicos Cardíacos , Fatores de Coagulação Sanguínea/fisiologia , Ponte Cardiopulmonar , Hemostasia Cirúrgica , Humanos , Microcirculação , Sistemas Automatizados de Assistência Junto ao Leito , Medição de Risco , Fatores de RiscoRESUMO
Patients undergoing cardiac surgery with cardiopulmonary bypass are at risk for excessive microvascular bleeding, which often leads to transfusion of allogeneic blood and blood components as well as reexploration in a smaller subset of patients. Excessive bleeding after cardiac surgery is generally related to a combination of several alterations in the hemostatic system pertaining to hemodilution, excessive activation of the hemostatic system, and potentially the use of newer, longer-acting antiplatelet or antithrombotic agents. Although several nonpharmacologic strategies have been proposed, this review summarizes the role of pharmacologic interventions as means to attenuate the alterations in the hemostatic system during CPB in an attempt to reduce excessive bleeding, transfusion, and reexploration. Specifically, agents that inhibit platelets, fibrinolysis, factor Xa and thrombin, as well as broad-spectrum agents, have been investigated with respect to their role in reducing consumption of clotting factors and better preservation of platelet function. Prophylactic administration of agents with antifibrinolytic, anticoagulant, and possibly antiinflammatory properties can decrease blood loss and transfusion. Although aprotinin seems to be the most effective blood conservation agent (which is most likely related to its broad-spectrum nature), agents with isolated antifibrinolytic properties may be as effective in low-risk patients. The ability to reduce blood product transfusions and to decrease operative times and reexploration rates favorably affects patient outcomes, availability of blood products, and overall health care costs.
Assuntos
Perda Sanguínea Cirúrgica/prevenção & controle , Circulação Extracorpórea/efeitos adversos , Hemostasia/efeitos dos fármacos , Antifibrinolíticos/uso terapêutico , Perda Sanguínea Cirúrgica/fisiopatologia , Humanos , Inibidores da Agregação Plaquetária/uso terapêutico , Trombina/antagonistas & inibidoresRESUMO
Guidelines for transfusion practice have had limited impact in altering physician transfusion behavior in patients undergoing cardiac operations. This may be due to a lack of consensus on the relative risks and benefits of blood in these patients who are anemic, limited access to timely data that are necessary on which to base transfusion decisions, the recognition that empiric hemoglobin/hematocrit thresholds are limited clinical indicators of the need for blood, or a combination of these. We present an overview of current transfusion and blood conservation practices in this setting, along with possible approaches to guide the decision-making process by coupling the use of transfusion algorithms with point of care testing to use more physiologic indicators of the need for blood transfusion.
Assuntos
Transfusão de Sangue , Procedimentos Cirúrgicos Cardíacos , Algoritmos , Transfusão de Sangue/normas , Procedimentos Cirúrgicos Cardíacos/normas , Hematócrito , Hemostasia Cirúrgica , Humanos , Guias de Prática Clínica como AssuntoRESUMO
BACKGROUND: Because previous reports suggest that the linear relationship between celite activated clotting time (ACT) values and heparin sodium is disrupted if values exceed 500 to 600 seconds, this study was designed to evaluate the relationship of kaolin activated clotting time (ACT) values to high in vitro heparin concentrations. In addition, the relationship of kaolin ACT to heparin concentration as determined manually was compared with that obtained with an automated heparin dose response assay. METHODS: Blood specimens were obtained prior to and after heparin administration from 41 cardiac surgical patients requiring cardiopulmonary bypass in this institutional human studies committee-approved study. Five ACT instruments were used to evaluate the response of kaolin ACT to manually added heparin at two anticoagulation levels: low range (ACT values of less than 500 seconds) and high range (ACT values of 500 seconds or greater). Specimens were also used to measure kaolin ACT values at three heparin concentrations with an automated heparin dose response assay (HDR) using a Hepcon instrument. RESULTS: A greater response of kaolin ACT to heparin was seen with high-range ACT values than low-range ACT values as illustrated by greater (p = 0.002) mean slope values (low range, 99 +/- 30 s/U/ mL; high range, 128 +/- 50 s/U/ml). Good correlations were obtained between heparin concentration and either low- or high-range ACT values as demonstrated by mean correlation coefficients (low range, 0.992; high range 0.982). The response of low-range kaolin ACT values to heparin was greater than that obtained with the automated heparin dose response assay as illustrated by greater (p = 0.005) mean slope values (low range, 99 +/- 30 s/U/mL; HDR, 82 +/- 21 s/U/mL). Good correlations were observed for the relationship between heparin and ACT values obtained with the HDR assay (r = 0.998). CONCLUSIONS: A variable response of kaolin ACT to heparin among patients was demonstrated in our study, especially when ACT values exceeded 500 seconds. We found that the response of kaolin ACT to higher heparin concentrations was acceptable for clinical monitoring based on good correlations obtained in individual patients. The HDR assay generally overestimates a patient's heparin requirements; most likely, this is due to a lower response of kaolin ACT to heparin concentration that is reflected in this assay. Because and exceptional correlation can be obtained between kaolin ACT values and heparin concentration using the assay, this automated assay can identify heparin-resistant patients who may need further treatment.
Assuntos
Anticoagulantes/administração & dosagem , Ponte Cardiopulmonar , Heparina/administração & dosagem , Monitorização Intraoperatória , Tempo de Coagulação do Sangue Total , Adulto , Anticoagulantes/uso terapêutico , Relação Dose-Resposta a Droga , Heparina/uso terapêutico , Humanos , Caulim , Modelos LinearesRESUMO
Twenty cardiac surgical patients requiring cardiopulmonary bypass were enrolled in this study designed to evaluate the effect of aprotinin on activated clotting time (kaolin and celite), whole blood, and laboratory-based plasma (anti-Xa) heparin measurements. Whole blood heparin measurements were not different (p = 0.98) between aprotinin-treated (3.2 +/- 2.8 U/mL) and control (3.2 +/- 3.0 U/mL) specimens. Plasma anti-Xa heparin measurements were also not different (p = 0.95) between aprotinin-treated (2.7 +/- 2.5 U/mL) and control (2.8 +/- 2.5 U/mL) specimens. The relationship between whole blood (plasma equivalent) and plasma heparin measurements was similar (p = 0.1) in the presence (slope, 1.04; r2 = 0.89) or absence (slope, 1.11; r2 = 0.89) of aprotinin. In contrast to weak correlations between celite (r = 0.50) or kaolin (r = 0.53) activated clotting time values, whole blood heparin measurements correlated well (r = 0.93) with plasma heparin measurements during cardiopulmonary bypass in the presence of aprotinin. These findings indicate that whole blood heparin measurements are unaffected by aprotinin and correlate well with plasma anti-Xa heparin measurements even in the presence of aprotinin. Therefore, the automated protamine titration assay can be used to monitor accurately heparin concentrations in patients receiving aprotinin.
Assuntos
Aprotinina/farmacologia , Heparina/sangue , Tempo de Coagulação do Sangue Total , Ponte Cardiopulmonar , Terra de Diatomáceas/farmacologia , Humanos , Caulim/farmacologia , Plasma/químicaRESUMO
BACKGROUND: Historically, warfarin has been discontinued or rapidly reversed with fresh frozen plasma in patients awaiting heart transplantation because of concerns regarding excessive bleeding. Because preoperative warfarin may have effects on bleeding after cardiac operations, we reviewed our experience to determine the risks in patients undergoing heart transplantation while maintained on warfarin. METHODS: The records of consecutive adult patients undergoing heart transplantation from January 1996 to December 1998 were reviewed. Preoperative and 24-hour postoperative data were obtained, including patient demographics; hematologic laboratory values; medication use; repeat or primary sternotomy data; allogeneic blood product administration; and chest tube drainage. Multivariate linear and logistic regression analyses were performed using these variables to determine risk factors for bleeding after heart transplantation. RESULTS: Ninety adult patients, mean age 50 years, underwent orthotopic heart transplantation during the 36-month period. No relationships existed between preoperative international normalized ratio (INR, mean = 1.83 +/- 0.1, p = 0.84) or postoperative INR (mean = 2.2 +/- 0.9, p = 0.63) and chest tube drainage (mean = 721 +/- 63 mL). Relationships were observed between total blood product administration and preoperative INR (partial r = 0.30, p = 0.01) and postoperative INR (partial r = -0.37, p = 0.002); however, preoperative INR did not correlate (p = 0.29) when perioperative use of fresh frozen plasma was factored as a covariate. Inverse relationships were evident between postoperative INR and total blood product exposures, as well as transfusions of platelets (partial r = -0.26, p = 0.03), fresh frozen plasma (partial r = -0.28, p = 0.02), and red cells (partial r = -0.25, p = 0.04). CONCLUSIONS: Although we noted no correlations between INR and chest tube output, inverse relationships were observed with transfusion requirements in the first 24 hours after transplantation. Preoperative warfarin may be safely continued in patients awaiting heart transplantation.
Assuntos
Transplante de Coração , Hemorragia Pós-Operatória/induzido quimicamente , Varfarina/efeitos adversos , Adulto , Idoso , Idoso de 80 Anos ou mais , Aspirina/efeitos adversos , Aspirina/uso terapêutico , Transfusão de Sangue , Tubos Torácicos , Humanos , Coeficiente Internacional Normatizado , Modelos Logísticos , Pessoa de Meia-Idade , Análise Multivariada , Contagem de Plaquetas , Cuidados Pós-Operatórios , Cuidados Pré-Operatórios , Curva ROC , Fatores de Risco , Varfarina/administração & dosagemRESUMO
BACKGROUND: Perioperative monitoring of pulmonary artery (PA) pressures in lung transplant recipients is critical. This report characterizes an intraoperative gradient across the PA anastomosis in a series of patients undergoing bilateral sequential lung transplantation. METHODS: Hemodynamic measurements were obtained in a series of 10 patients before anesthetic induction, during one-lung ventilation/perfusion of the newly transplanted first lung with the PA catheter proximal and distal to the anastomosis and after arrival in the intensive care unit. The following measurements were recorded: central venous pressure, cardiac output, PA occlusion pressure, and systemic and pulmonary arterial pressures (systolic, diastolic, mean). RESULTS: Although a systolic pressure gradient of more than 10 mm Hg across the anastomosis was observed in all patients, there was a significant variation in systolic (13 to 59 mm Hg), diastolic (2 to 10 mm Hg), and mean (5 to 27 mm Hg) PA gradients. Mean proximal systolic PA pressure measurements (56.2 +/- 20.6 mm Hg) were greater when compared to measurements obtained distal to the anastomosis (28.6 +/- 10.1 mm Hg, p = 0.001) and to those obtained in the postoperative period (32.1 +/- 9.7 mm Hg, p = 0.004). CONCLUSIONS: The present study demonstrates that during single-lung ventilation and perfusion, the PA pressure measured proximally may not reflect accurately the pressure distal to the vascular anastomosis.
Assuntos
Anastomose Cirúrgica , Pressão Sanguínea , Transplante de Pulmão/fisiologia , Artéria Pulmonar/cirurgia , Débito Cardíaco , Cateterismo , Pressão Venosa Central , Diástole , Feminino , Humanos , Cuidados Intraoperatórios , Pulmão/fisiopatologia , Pulmão/cirurgia , Masculino , Pessoa de Meia-Idade , Cuidados Pós-Operatórios , Artéria Pulmonar/fisiopatologia , Pressão Propulsora Pulmonar , Sístole , Resistência Vascular , Relação Ventilação-PerfusãoRESUMO
BACKGROUND: We assessed the efficacy of a continuous infusion of nicardipine and nitroglycerin in reducing the incidence and severity of perioperative myocardial ischemia during elective coronary artery bypass grafting procedures in a prospective, randomized, controlled study. METHODS: Patients received either nicardipine infusion (0.7 to 1.4 microg x kg(-1) x min(-1); n = 30) or nitroglycerin (0.5 to 1 microg x kg(-1) x min(-1); n = 30) or neither medication (n = 17) after aortic occlusion clamp release and for 24 hours postoperatively. Myocardial ischemic episodes (MIE) were considered to have occurred with ST-segment depressions or elevations of at least 1 mm and at least 2 mm (for both depressions or elevations), each at J + 60 ms and lasting at least 1 minute, using a two-channel Holter monitor. RESULTS: Only nicardipine significantly decreased the duration (p = 0.02) of the 1-mm or greater minutes per hour (3.2 +/- 1.2 minutes per hour) and eliminated the number (p = 0.02) of the 2-mm or greater minutes per hour (zero minutes per hour) when compared with control patients (17.2 +/- 5.6 minutes per hour and 0.17 minutes per hour, respectively) during the intraoperative postbypass period. CONCLUSIONS: Our results suggest that nicardipine lessened the severity of myocardial ischemia shortly after coronary revascularization and could be considered as an alternative to standard antiischemic therapy.
Assuntos
Ponte de Artéria Coronária , Doença das Coronárias/cirurgia , Isquemia Miocárdica/tratamento farmacológico , Nicardipino/administração & dosagem , Nitroglicerina/administração & dosagem , Complicações Pós-Operatórias/tratamento farmacológico , Vasodilatadores/administração & dosagem , Idoso , Relação Dose-Resposta a Droga , Eletrocardiografia Ambulatorial/efeitos dos fármacos , Feminino , Hemodinâmica/efeitos dos fármacos , Humanos , Infusões Intravenosas , Masculino , Pessoa de Meia-Idade , Isquemia Miocárdica/diagnóstico , Nicardipino/efeitos adversos , Nitroglicerina/efeitos adversos , Complicações Pós-Operatórias/diagnóstico , Estudos Prospectivos , Resultado do Tratamento , Vasodilatadores/efeitos adversosRESUMO
BACKGROUND: Abciximab during percutaneous coronary revascularization reduces ischemic complications, but concern exists regarding increased bleeding risk should emergency coronary surgical procedures be required. METHODS: Outcomes were assessed among 85 patients who required coronary artery bypass grafting operations after coronary intervention in two randomized placebo-controlled trials of abciximab. Comparisons were made between patients in the pooled placebo and abciximab groups. RESULTS: The incidence of coronary surgical procedures was 2.17% and 1.28% among patients randomized to placebo and abciximab, respectively (p = 0.021). Platelet transfusions were administered to 32% and 52% of patients in the placebo and abciximab groups, respectively (p = 0.059). Rates of major blood loss were 79% and 88% in the placebo and abciximab groups, respectively (p = 0.27); transfusions of packed red blood cells or whole blood were administered in 74% and 80% of patients, respectively (p = 0.53). Surgical reexploration for bleeding was required in 3% and 12% of patients, respectively. Death and myocardial infarction tended to occur less frequently among patients who had received abciximab. CONCLUSIONS: Urgent coronary artery bypass grafting operations can be performed without an incremental increase in major hemorrhagic risk among patients on abciximab therapy.
Assuntos
Anticorpos Monoclonais/uso terapêutico , Perda Sanguínea Cirúrgica , Ponte de Artéria Coronária , Fragmentos Fab das Imunoglobulinas/uso terapêutico , Inibidores da Agregação Plaquetária/uso terapêutico , Abciximab , Angioplastia Coronária com Balão , Tratamento de Emergência , Humanos , Estudos Multicêntricos como Assunto , Ensaios Clínicos Controlados Aleatórios como Assunto , Fatores de Risco , StentsRESUMO
This study was designed to evaluate the effects of varying concentrations of platelets, white blood cells (WBC) and Fab fragments of a monoclonal antibody (c7E3, Reopro) directed at the platelet GpIIb-IIIa receptor complex on ACT-based clot ratio values (hemoSTATUS assay) in healthy volunteers. These measurements were made in heparinized whole blood from 10 normal volunteers in which either platelet or WBC concentrations had been varied by differential centrifugation. In addition, blood collected in either heparin or argatroban was incubated with varying concentrations of c7E3 (Reopro). Clot ratio values (%Maximal) in normal blood did not decrease until average platelet counts were less than 50,000. A marked reduction in clot ratios was observed when WBC concentration increased above or decreased below baseline clot ratios within each patient. Strong linear relationships were observed between white cell concentration and clot ratio values when white cell concentrations were either less or greater than baseline values. When argatroban was used as an anticoagulant, inverse relationships were demonstrated between clot ratio values and increasing c7E3 concentration (Ch 3: r = -0.33, Ch4: r = -0.84, Ch5: r = -0.87, Ch 6: r = -0.71). ACT-based clot ratio values determined in heparinized whole blood presumably reflecting PAF inducible platelet procoagulant activity, are affected by platelet concentration when counts are less than 50,000/microliter. The hemoSTATUS test was also found to be affected by WBC concentration since clot ratio values decreased when WBC counts were below 4,000/microliter or above 9,000/microliter. A dose-dependent reduction in clot ratio values was also observed with increasing concentrations of c7E3. This test can reliably detect platelet dysfunction only if the platelet count is > 50,000 and the WBC is normal.
Assuntos
Testes de Coagulação Sanguínea/métodos , Fator de Ativação de Plaquetas/análise , Abciximab , Adulto , Anticorpos Monoclonais , Ponte Cardiopulmonar/efeitos adversos , Estudos de Avaliação como Assunto , Hemostasia , Humanos , Fragmentos Fab das Imunoglobulinas , Contagem de Leucócitos , Contagem de Plaquetas , Complexo Glicoproteico GPIIb-IIIa de Plaquetas/antagonistas & inibidores , Complexo Glicoproteico GPIIb-IIIa de Plaquetas/imunologia , Complicações Pós-Operatórias/sangue , Complicações Pós-Operatórias/diagnóstico , Complicações Pós-Operatórias/etiologia , Valores de ReferênciaRESUMO
There is still no alternative that is as effective or as well tolerated as blood; nevertheless, the search for ways to conserve, and even eliminate blood transfusion, continues. Based on hemoglobin levels, practice guidelines for the use of perioperative transfusion of red blood cells in patients undergoing coronary artery bypass grafting have been formulated by the National Institutes of Health and the American Society of Anesthesiologists. However, it has been argued that more physiologic indicators of adequacy of oxygen delivery should be used to assess the need for blood transfusion. Methods used for conserving blood during surgery include autologous blood donation, acute normovolemic hemodilution and intra- and postoperative blood recovery and reinfusion. The guidelines for the use of autologous blood transfusion are controversial and it does not appear to be cost effective compared with allogeneic blood transfusion in patients undergoing cardiac surgery. Similarly, the cost effectiveness of intra- and postoperative blood recovery and reinfusion need further evaluation. Treatment with recombinant human erythropoietin (rhEPO) remains unapproved in the US for patients undergoing cardiac or vascular surgery, but it is a valuable adjunct in Jehovah's Witness patients, for whom blood is unacceptable. The characterization of darbepoetin alfa, a novel erythropoiesis stimulating protein with a 3-fold greater plasma elimination half-life compared with rhEPO, is an important advance in this field. Darbepoetin alfa appears to be effective in treating the anemia in patients with renal failure or cancer and trials in patients with surgical anemia are planned. Desmopressin has been used to effectively reduce intraoperative blood loss. Topical agents to prevent blood loss, such as fibrin glue and fibrin gel, and agents that alter platelet function, such as aspirin (acetylsalicylic acid) or dipyridamole, need further evaluation in patients undergoing cardiac surgery. Aprotinin has been shown to preserve hemostasis and reduce allogeneic blood exposure to a greater extent than the antifibrinolytic agents tranexamic acid and aminocaproic acid. Controlled clinical trials comparing the costs of these agents with clinical outcomes, along with tolerability profiles in patients at risk for substantial perioperative bleeding are needed.
Assuntos
Transfusão de Sangue/métodos , Procedimentos Cirúrgicos Cardíacos , Perda Sanguínea Cirúrgica/prevenção & controle , Coleta de Amostras Sanguíneas , Transfusão de Sangue Autóloga/métodos , Ensaios Clínicos como Assunto , Cuidados Críticos/métodos , Eritropoetina/uso terapêutico , Hemodiluição , Hemostasia Cirúrgica/métodos , Humanos , Cuidados Intraoperatórios , Cuidados Pós-Operatórios , Proteínas RecombinantesRESUMO
Medical practice guidelines have been promoted as a way to improve the cost-effectiveness of medical care. Algorithms for the transfusion of red blood cells, plasma, and platelets may be especially useful in the surgical setting if they incorporate point-of-care information that is both physiologic and patient-specific for transfusion decision making. Therefore, the goals of guidelines for surgical blood management should be twofold. They should (1) acknowledge patient-specific variability while addressing physician- and institution-dependent variables; and (2) improve blood component management by developing more physiologic clinical indicators of the need for allogeneic red blood cell transfusion.
Assuntos
Perda Sanguínea Cirúrgica/prevenção & controle , Transfusão de Sangue/normas , Guias de Prática Clínica como Assunto , Procedimentos Cirúrgicos Operatórios , Algoritmos , Transfusão de Sangue/economia , Ponte de Artéria Coronária , Análise Custo-Benefício , Transfusão de Eritrócitos/métodos , Técnicas Hemostáticas , HumanosRESUMO
Patients undergoing cardiac surgery with cardiopulmonary bypass (CPB) are at increased risk for excessive perioperative blood loss requiring transfusion of blood products. Point-of-care evaluation of platelets, coagulation factors, and fibrinogen can enable physicians to rapidly assess bleeding abnormalities, facilitate the optimal administration of pharmacological and transfusion-based therapy, and also identify patients with surgical bleeding. The ability to reduce the unnecessary use of blood products in this setting has important implications for emerging issues in blood inventory and blood costs. The ability to decrease surgical time, along with exploration rates, has important consequences for health care costs in an increasingly managed health care environment.
Assuntos
Procedimentos Cirúrgicos Cardíacos , Hemostasia Cirúrgica , Hemorragia Pós-Operatória/prevenção & controle , Algoritmos , Testes de Coagulação Sanguínea/instrumentação , Testes de Coagulação Sanguínea/métodos , Transfusão de Sangue , Desamino Arginina Vasopressina/uso terapêutico , Fibrinólise , Hemostasia/fisiologia , Hemostáticos/uso terapêutico , Humanos , Sistemas Automatizados de Assistência Junto ao Leito , Hemorragia Pós-Operatória/diagnóstico , Fatores de RiscoRESUMO
Perioperative myocardial ischemic episodes are predictive of adverse cardiac outcomes after coronary artery bypass surgery. We compared the efficacy of continuous infusions of nicardipine (group NIC) and nitroglycerin (group NTG) in reducing the frequency and severity of myocardial ischemic episodes. Patients received either a nicardipine infusion, 0.7 to 1.4 microg/kg/min (n = 30), nitroglycerin infusion, 0.5 to 1 microg/kg/min (n = 30), or neither medication (group C; n = 17) after aortic occlusion clamp release and for 24 hours postoperatively. Myocardial ischemic episodes were considered as ST segment depressions or elevations of 1 mm or greater from baseline, each at J + 60 milliseconds and lasting 1 minute or greater, using a two-channel Holter monitor. Only nicardipine significantly decreased the duration (3.2 +/- 1.2 min/h) and the area under the ST time curve (AUC; 5.7 +/- 15.7 AUC/h) of 1-mm or greater myocardial ischemic episodes compared with group C (17.2 +/- 5.6 min/h and 30.1 +/- 49 AUC/h, respectively) during the intraoperative postbypass period. A trend toward lower frequency, duration, and area under the ST time curve of myocardial ischemic episodes was observed in group NIC compared with group NTG. Cardiac indices and mixed venous oxygen saturations were significantly greater, whereas systemic pressures were less in group NIC compared with group NTG for the same period. These results suggest that nicardipine, but not nitroglycerin, decreased the duration and area under the ST time curve of myocardial ischemic episodes shortly after coronary revascularization. Larger studies are required to verify the efficacy of nicardipine in reducing the severity of myocardial ischemia during cardiac surgery.