Mark H. Ereth

Efficacy of a simple intraoperative transfusion algorithm for nonerythrocyte component utilization after cardiopulmonary bypass.

Background Abnormal bleeding after cardiopulmonary bypass (CPB) is a common complication of cardiac surgery, with important health and economic consequences. Coagulation test–based algorithms may reduce transfusion of non-erythrocyte allogeneic blood in patients with abnormal bleeding. Methods The authors performed a randomized prospective trial comparing allogeneic transfusion practices in 92 adult patients with abnormal bleeding after CPB. Patients with abnormal bleeding were randomized to one of two groups: a control group following individual anesthesiologist’s transfusion practices and a protocol group using a transfusion algorithm guided by coagulation tests. Results Among 836 eligible patients having all types of elective cardiac surgery requiring CPB, 92 patients developed abnormal bleeding after CPB (incidence, 11%). The transfusion algorithm group received less allogeneic fresh frozen plasma in the operating room after CPB (median, 0 units; range, 0–7 units) than the control group (median, 3 units; range, 0–10 units) (P = 0.0002). The median number of platelet units transfused in the operating room after CPB was 4 (range, 0–12) in the algorithm group compared with 6 (range, 0–18) in the control group (P = 0.0001). Intensive care unit (ICU) mediastinal blood loss was significantly less in the algorithm group. Multivariate analysis demonstrated that transfusion algorithm use resulted in reduced ICU blood loss. The control group also had a significantly greater incidence of surgical reoperation of the mediastinum for bleeding (11.8%vs. 0%;P = 0.032). Conclusions Use of a coagulation test–based transfusion algorithm in cardiac surgery patients with abnormal bleeding after CPB reduced non-erythrocyte allogeneic transfusions in the operating room and ICU blood loss.

Thirty-Day Mortality After Elective Total Hip Arthroplasty

Background: Previous reports on perioperative mortality associated with hip arthroplasty have not documented, to our knowledge, patient characteristics and surgical factors that increase the likelihood of death. The purpose of this study was to determine the prevalence of and associated risk factors for perioperative death after elective hip arthroplasty. Methods: The records of 30,714 consecutive patients who had undergone elective hip arthroplasty at our institution from 1969 to 1997 were retrospectively reviewed to identify patients who had died within thirty days after the procedure. Mortality rates were determined according to age, gender, diagnosis, implant type, and fixation mode. Results: Ninety deaths occurred within thirty days after elective total hip arthroplasty, for an overall mortality rate of 0.29% (ninety of 30,714). The thirty-day mortality rate was significantly higher for patients with preexisting cardiovascular disease (p < 0.0001), male patients (p < 0.0001), and patients who were seventy years of age or older (p < 0.0002). The mortality rate was slightly, but not significantly, higher for patients with an underlying diagnosis of rheumatoid arthritis (p < 0.36) and those receiving cemented implants (p < 0.57). There was no difference in the thirty-day mortality rate for revision as compared with primary hip arthroplasty (p < 0.92). Conclusions: Factors that are associated with an increased risk of mortality within thirty days after elective hip arthroplasty include an older age, male gender, and a history of cardiorespiratory disease. There has been a significant decline in the thirty-day mortality rate after elective hip arthroplasty in the last decade (p < 0.0002); during the 1990s, the overall rate at our institution was 0.15% (twenty-three of 14,989).

Cemented Versus Noncemented Total Hip Arthroplasty—Embolism, Hemodynamics, and Intrapulmonary Shunting

Bone cement implantation syndrome is characterized by hypotension, hypoxemia, cardiac arrhythmias, cardiac arrest, or any combination of these complications. It may result from venous embolization that occurs in conjunction with intramedullary hypertension in the femur during insertion of the prosthesis in patients undergoing cemented total hip arthroplasty (THA). Intramedullary hypertension does not occur in patients undergoing noncemented THA. In this study, we sought to compare embolization between patients undergoing cemented and noncemented THA and to determine whether this state resulted in cardiorespiratory deterioration. In this prospective investigation of 35 patients undergoing elective THA, we used transesophageal echocardiography and invasive hemodynamic monitoring, and in 12 of them, we monitored distribution of pulmonary ventilation and perfusion intraoperatively. Embolization was significantly greater after insertion of the prosthesis in patients undergoing cemented than in those undergoing noncemented THA. Cemented THA was also associated with decreased cardiac output and increased pulmonary artery pressure and pulmonary vascular resistance. Increases in ventilation-perfusion mismatching, however, could not be demonstrated 30 minutes after insertion of the femoral prosthesis. Intraoperative monitoring for embolism may help physicians assess patients in whom cardiorespiratory function deteriorates during THA.

Plasma Tranexamic Acid Concentrations During Cardiopulmonary Bypass

Although tranexamic acid is used to reduce bleeding after cardiac surgery, there is large variation in the recommended dose, and few studies of plasma concentrations of the drug during cardiopulmonary bypass (CPB) have been performed. The plasma tranexamic acid concentration reported to inhibit fibrinolysis in vitro is 10 &mgr;g/mL. Twenty-one patients received an initial dose of 10 mg/kg given over 20 min followed by an infusion of 1 mg · kg−1 · h−1 via a central venous catheter. Two patients were removed from the study secondary to protocol violation. Perioperative plasma tranexamic acid concentrations were measured with high-performance liquid chromatography. Plasma tranexamic acid concentrations (&mgr;g/mL; mean ± sd [95% confidence interval]) were 37.4 ± 16.9 (45.5, 29.3) after bolus, 27.6 ± 7.9 (31.4, 23.8) after 5 min on CPB, 31.4 ± 12.1 (37.2, 25.6) after 30 min on CPB, 29.2 ± 9.0 (34.6, 23.8) after 60 min on CPB, 25.6 ± 18.6 (35.1, 16.1) at discontinuation of tranexamic acid infusion, and 17.7 ± 13.1 (24.1, 11.1) 1 h after discontinuation of tranexamic acid infusion. Four patients with renal insufficiency had increased concentrations of tranexamic acid at discontinuation of the drug. Repeated-measures analysis revealed a significant main effect of abnormal creatinine concentration (P = 0.02) and time (P < 0.001) on plasma tranexamic acid concentration and a significant time × creatinine concentration interaction (P < 0.001).

Thirty-day mortality following hip arthroplasty for acute fracture.

BACKGROUND Hip fractures are associated with a substantial mortality rate. Previous reports on perioperative mortality associated with hip arthroplasty for the treatment of acute fracture have not documented demographic and surgical characteristics that increase the likelihood of death. The purpose of the present study was to determine the prevalence of, and associated risk factors for, perioperative death following hip arthroplasty for the treatment of acute fracture. METHODS Data were compiled from the computerized total joint registry at a single institution to determine the mortality rate following hip arthroplasty according to age, gender, diagnosis, implant type, and fixation mode. A review of this database revealed that 7774 consecutive patients had undergone hip arthroplasty for the treatment of an acute fracture between 1969 and 1997. The medical records of all patients who had died within thirty days after hip arthroplasty were reviewed retrospectively. RESULTS The overall mortality rate within thirty days after hip arthroplasty for the treatment of an acute fracture was 2.4% (186 of 7774), yet notable variations in the mortality rate were seen within clinical subgroups. The thirty-day mortality rate was significantly higher for patients who had received a cemented implant, female patients, elderly patients, patients with cardiorespiratory comorbidities, and patients with intertrochanteric fractures. With the numbers available, there was no significant difference in mortality between patients who had been managed with total hip arthroplasty and those who had been managed with hemiarthroplasty. CONCLUSIONS Hip arthroplasty for the diagnosis of acute fracture is associated with a nearly tenfold higher rate of perioperative mortality compared with elective hip arthroplasty. Medical optimization, appropriate choice of implants, and vigilant intraoperative management of these patients are essential.

Comparison of Blood-conservation Strategies in Cardiac Surgery Patients at High Risk for Bleeding

Background: Aprotinin and tranexamic acid are routinely used to reduce bleeding in cardiac surgery. There is a large difference in agent price and perhaps in efficacy. Methods: In a prospective, randomized, partially blinded study, 168 cardiac surgery patients at high risk for bleeding received either a full-dose aprotinin infusion, tranexamic acid (10-mg/kg load, 1-mg · kg−1 · h−1 infusion), tranexamic acid with pre–cardiopulmonary bypass autologous whole-blood collection (12.5% blood volume) and reinfusion after cardiopulmonary bypass (combined therapy), or saline infusion (placebo group). Results: There were complete data in 160 patients. The aprotinin (n = 40) and combined therapy (n = 32) groups (data are median [range]) had similar reductions in blood loss in the first 4 h in the intensive care unit (225 [40–761] and 163 [25–760] ml, respectively;P = 0.014), erythrocyte transfusion requirements in the first 24 h in the intensive care unit (0 [0–3] and 0 [0–3] U, respectively;P = 0.004), and durations of time from end of cardiopulmonary bypass to discharge from the operating room (92 [57–215] and 94 [37, 186] min, respectively;P = 0.01) compared with the placebo group (n = 43). Ten patients in the combined therapy group (30.3%) required transfusion of the autologous blood during cardiopulmonary bypass for anemia. Conclusions: The combination therapy of tranexamic acid and intraoperative autologous blood collection provided similar reduction in blood loss and transfusion requirements as aprotinin. Cost analyses revealed that combined therapy and tranexamic acid therapy were the least costly therapies.

Does the Platelet-activated Clotting Test (hemostatus[registered sign]) Predict Blood Loss and Platelet Dysfunction Associated with Cardiopulmonary Bypass?

Platelet dysfunction is a major cause of bleeding after cardiopulmonary bypass (CPB).No timely, simple, point-of-care determinant of platelet function is available for clinical use. Adding platelet-activating factor to conventional activated clotting time methods (platelet-activated clotting test [PACT]) (HemoSTATUS[registered sign]; Medtronic, Inc., Parker, CO) produces rapid results (<3 min) and may yield a measure of platelet responsiveness and whole blood procoagulant activity. Blood samples were drawn for PACT, platelet count, prothrombin time, activated partial thromboplastin time, and thromboelastogram (TEG) from 200 patients undergoing cardiac surgery. The PACT significantly decreased from the baseline to postprotamine time interval (P < 0.001). The PACT correlated with 4-h mediastinal blood loss (r = -0.30, P = 0.014). The TEG maximum amplitude also correlated with 4-h mediastinal blood loss (r = -0.32, P = 0.003). The PACT had a sensitivity and specificity comparable to routine laboratory coagulation tests in predicting blood loss. The TEG maximum amplitude, however, was more predictive than both the PACT and routine coagulation tests in this respect. The PACT may be a useful indicator of platelet responsiveness or whole blood procoagulant activity, but we did not find it superior to other tests of coagulation function for predicting excessive blood loss after CPB. (Anesth Analg 1997;85:259-64)

Characterizing the Epidemiology of Perioperative Transfusion-associated Circulatory Overload

Background:Transfusion-associated circulatory overload (TACO) is a leading cause of transfusion-related fatalities, but its incidence and associated patient and transfusion characteristics are poorly understood. To inform surgical transfusion practice and to begin mitigating perioperative TACO, the authors aimed to define its epidemiology. Methods:In this retrospective cohort study, the medical records of adult patients undergoing noncardiac surgery with general anesthesia during 2004 or 2011 and receiving intraoperative transfusions were screened using an electronic algorithm for identification of TACO. Those patients who were screened as high probability for TACO underwent rigorous manual review. Univariate and multivariate analyses evaluated associations between patient and transfusion characteristics with TACO rates in a before-and-after study design. Results:A total of 2,162 and 1,908 patients met study criteria for 2004 and 2011, respectively. The incidence of TACO was 5.5% (119 of 2,162) in 2004 versus 3.0% (57 of 1,908) in 2011 (P < 0.001), with comparable rates for men (4.8% [98 of 2,023]) and women (3.8% [78 of 2,047]) (P = 0.09). Overall, vascular (12.1% [60 of 497]), transplant (8.8% [17 of 193]), and thoracic surgeries (7.2% [10 of 138]) carried the highest TACO rates. Obstetric and gynecologic patients had the lowest rate (1.4% [4 of 295]). The incidence of TACO increased with volume transfused, advancing age, and total intraoperative fluid balance (all P < 0.001). Conclusions:The incidence of perioperative TACO is similar to previous estimates in nonsurgical populations. There was a reduction in TACO rate between 2004 and 2011, with incidence patterns remaining comparable in subgroup analyses. Future efforts exploring risk factors for TACO may guide preventive or therapeutic interventions, helping to further mitigate this transfusion complication.

Quantification of hypercoagulable state after blunt trauma: Microparticle and thrombin generation are increased relative to injury severity, while standard markers are not

BACKGROUND Major trauma is an independent risk factor for developing venous thromboembolism. While increases in thrombin generation and/or procoagulant microparticles have been detected in other patient groups at greater risk for venous thromboembolism, such as cancer or coronary artery disease, this association has yet to be documented in trauma patients. This pilot study was designed to characterize and quantify thrombin generation and plasma microparticles in individuals early after traumatic injury. METHODS Blood was collected in the trauma bay from 52 blunt injured patients (cases) and 19 uninjured outpatients (controls) and processed to platelet poor plasma to allow for (1) isolation of microparticles for identification and quantification by flow cytometry, and (2) in vitro thrombin generation as measured by calibrated automatic thrombography. Data collected are expressed as either mean ± standard deviation or median with interquartile range. RESULTS Among the cases, which included 39 men and 13 women (age, 40 ± 17 years), the injury severity score was 13 ± 11, the international normalized ratio was 1.0 ± 0.1, the thromboplastin time was 25 ± 3 seconds, and platelet count was 238 ± 62 (thousands). The numbers of total (cell type not specified) procoagulant microparticles, as measured by Annexin V staining, were increased compared to nontrauma controls (541 ± 139/μL and 155 ± 148/μL, respectively; P < .001). There was no significant difference in the amount of thrombin generated in trauma patients compared to controls; however, peak thrombin was correlated to injury severity (Spearman correlation coefficient R, 0.35; P = .02). CONCLUSION Patients with blunt trauma have greater numbers of circulating procoagulant microparticles and increased in vitro thrombin generation. Future studies to characterize the cell-specific profiles of microparticles and changes in thrombin generation kinetics after traumatic injury will determine whether microparticles contribute to the hypercoagulable state observed after injury.

Autologous platelet-rich plasma does not reduce transfusion of homologous blood products in patients undergoing repeat valvular surgery

Background:Patients undergoing cardiac surgery employing cardiopulmonary bypass frequently require transfusion of homologous blood products and, therefore, are exposed to the risk of transfusions. Autologous platelet-rich plasma administration may reduce homologous transfusion and attendant risks. Methods:In a blinded, randomized fashion, patients undergoing repeat sternotomy and valvular surgery received either a sham product (n = 28) or autologous platelet-rich plasma (n = 28) at the conclusion of cardiopulmonary bypass. Perioperative blood loss, coagulation profiles, and transfusion requirements were compared between the two groups. Results:In the first 24 h postoperatively, both the plateletrich plasma and sham groups received a median of 10.5 units of homologous blood products. Total median perioperative homologous transfusion requirements were 13 and 11.5 units for the platelet-rich plasma and sham groups, respectively. Conclusions:Autologous platelet-rich plasma did not reduce perioperative bleeding or transfusion requirements in repeat valvular surgery.