Hemodilution and surgical hemostasis contribute significantly to transfusion requirements in patients undergoing coronary artery bypass

Which factors have a great impact on coagulopathy and hemostatic impairment after cardiopulmonary bypass in cardiovascular surgery? An analysis based on rotational thromboelastometry

OBJECTIVES

This study aimed to investigate which factors have a great impact on coagulopathy after cardiopulmonary bypass (CPB) using rotational thromboelastometry (ROTEM).

METHODS

Ninety-eight patients undergoing cardiovascular surgery using CPB were enrolled. Data of amplitude 10 min after clotting time (A10) of ROTEM measured routinely before and after CPB were retrospectively collected. ROTEM has some assays by which we can evaluate the capacity of extrinsic coagulation (EXTEM), intrinsic coagulation (INTEM), fibrin polymerization (FIBTEM), and the effect of heparin (HEPTEM). The platelet component, defined as PLTEM, can be calculated by subtracting FIBTEM from EXTEM. Age, sex, total plasma volume, pre-CPB A10, lowest body temperature, in-out balance during CPB, intraoperative bleeding amount, and type of pumps were considered as possible factors. Univariate and multivariate analyses were performed for the rate of change of A10.

RESULTS

The change rate of each A10 had a significant negative correlation with bleeding amount (p < 0.01 for EXTEM, p < 0.01 for INTEM, p = 0.02 for FIBTEM, p < 0.01 for PLTEM). Female sex was a significant contributive predictor for the greater decline of EXTEM (p < 0.01) and INTEM (p < 0.01), positive balance for EXTEM (p < 0.01), FIBTEM (p = 0.01), and PLTEM (p < 0.01), long CPB time for INTEM (p = 0.01), centrifugal pump for FIBTEM (p < 0.01), and large pre-CPB A10 for PLTEM (p < 0.01).

CONCLUSION

In perioperative hemostatic management using ROTEM, attention should be given to the effects of these multiple factors.

Evaluation of risk scores in predicting perioperative blood transfusions in adult cardiac surgery

Objective:

Allogeneic blood product transfusions are associated with an increased morbidity and mortality risk in cardiac surgery. At present, a few transfusion risk scores have been proposed for cardiac surgery patients. The present study is aimed to develop a new score and to compare with preexisting scores – Transfusion Risk and Clinical Knowledge (TRACK) and Transfusion Risk Understanding Scoring Tool (TRUST) score.

Methodology:

A total of 1014 adult patients undergoing cardiac surgery were enrolled in the retrospective study. Independent predictors of allogeneic blood transfusions were selected from TRACK and TRUST scores. A predictive score was developed from six variables using logistic regression analysis, and new score was compared to the other existing scores – TRACK and TRUST.

Results:

The new score had following predictors: age >58 years, weight <63 kg for males and <49 kg for females, gender (female), complex surgery, hemoglobin <13.5 g/dl, and creatinine >1.36 mg/dl. Validation of new score demonstrated an acceptable predictive power (area under the curve [AUC] 0.749) and a good calibration at the Hosmer–Lemeshow test. New score was comparable with TRACK score with P = 0.578 (AUC of TRACK 0.756 and AUC of new score 0.749). There was a significant difference between new score and TRUST score, P = 0.01 (AUC of TRUST 0.72 and AUC of new score 0.749).

Conclusion:

New score is a simple risk model based on six predictors having a similar accuracy and calibration in predicting the transfusion rate in cardiac surgery as compared to TRACK score.

Fish Oil and Perioperative Bleeding

Background Fish oil is among the most common natural supplements for treatment of hypertriglyceridemia or prevention of cardiovascular disease. However, concerns about theoretical bleeding risk have led to recommendations that patients should stop taking fish oil before surgery or delay in elective procedures for patients taking fish oil by some health care professionals. Methods and Results We tested the effect of fish oil supplementation on perioperative bleeding in a multinational, placebo-controlled trial involving 1516 patients who were randomized to perioperative fish oil (eicosapentaenoic acid+docosahexaenoic acid; 8-10 g for 2-5 days preoperatively, and then 2 g/d postoperatively) or placebo. Primary outcome was major perioperative bleeding as defined by the Bleeding Academic Research Consortium. Secondary outcomes include perioperative bleeding per thrombolysis in myocardial infarction and International Society on Thrombosis and Hemostasis definitions, chest tube output, and total units of blood transfused. Participants' mean (SD) age was 63 (13) years, and planned surgery included coronary artery bypass graft (52%) and valve surgery (50%). The primary outcome occurred in 92 patients (6.1%). Compared with placebo, risk of Bleeding Academic Research Consortium bleeding was not higher in the fish oil group: odds ratio, 0.81; 95% CI, 0.53-1.24; absolute risk difference, 1.1% lower (95% CI, -3.0% to 1.8%). Similar findings were seen for secondary bleeding definitions. The total units of blood transfused were significantly lower in the fish oil group compared with placebo (mean, 1.61 versus 1.92; P<0.001). Evaluating achieved plasma phospholipid omega-3 polyunsaturated fatty acids levels with supplementation (on the morning of surgery), higher levels were associated with lower risk of Bleeding Academic Research Consortium bleeding, with substantially lower risk in the third (odds ratio, 0.30 [95% CI, 0.11-0.78]) and fourth (0.36 [95% CI, 0.15-0.87]) quartiles, compared with the lowest quartile. Conclusions Fish oil supplementation did not increase perioperative bleeding and reduced the number of blood transfusions. Higher achieved n-3-PUFA levels were associated with lower risk of bleeding. These novel findings support the need for reconsideration of current recommendations to stop fish oil or delay procedures before cardiac surgery. Clinical Trial Registration URL: https://www.clinicaltrials.gov . Unique identifier: NCT00970489.

Comparison of Outcomes and Complications of Transcatheter Aortic Valve Implantation in Women Versus Men (from the National Inpatient Sample)

Transcatheter aortic valve implantation (TAVI) is a rapidly emerging procedure for the treatment of intermediate and high-surgical-risk patients with severe aortic stenosis. The impact of gender on in-hospital outcomes has not been studied on a large scale. The aim of this study was to examine gender differences in in-hospital outcomes after TAVI. The National Inpatient Sample (2012 to 2014) using the International Classification of Diseases, 9th Revision, Clinical Modification procedure codes for TAVI (35.05 and 35.06) were used to form this database. Propensity score matching (1:1) was performed and in-hospital outcomes were compared. The primary outcome was in-hospital mortality. Statistical analysis was performed using SAS 9.4 (SAS Institute Inc., Cary, North Carolina). A total of 41,050 (weighted) patients were included in our study. Women accounted for 47.7% (n = 19,570) in our study and presented with older age (81.7 years vs 80.5 years, p ≤ 0.0001). The population was predominantly white (87.4%). After performing propensity score-matched analysis (1:1), no difference in the primary outcome was noted between men and women. The secondary outcomes including stroke, hemorrhage requiring transfusion, and pericardial complications were higher in women. The composite end point of death and stroke occurred more frequently in women than in men. Acute renal failure was higher in men. The post-TAVI length of stay was higher in women (8.3 days vs 7.7 days, p = 0.0007). In conclusion, this large, retrospective registry analysis of patients with severe aortic stenosis who underwent TAVI suggests women may experience higher rates of in-hospital morbidity compared with men.

Diagnostic and therapeutic medical devices for safer blood management in cardiac surgery: systematic reviews, observational studies and randomised controlled trials

Background

Anaemia, coagulopathic bleeding and transfusion are strongly associated with organ failure, sepsis and death following cardiac surgery.

Objective

To evaluate the clinical effectiveness and cost-effectiveness of medical devices used as diagnostic and therapeutic tools for the management of anaemia and bleeding in cardiac surgery.

Methods and results

Workstream 1 – in the COagulation and Platelet laboratory Testing in Cardiac surgery (COPTIC) study we demonstrated that risk assessment using baseline clinical factors predicted bleeding with a high degree of accuracy. The results from point-of-care (POC) platelet aggregometry or viscoelastometry tests or an expanded range of laboratory reference tests for coagulopathy did not improve predictive accuracy beyond that achieved with the clinical risk score alone. The routine use of POC tests was not cost-effective. A systematic review concluded that POC-based algorithms are not clinically effective. We developed two new clinical risk prediction scores for transfusion and bleeding that are available as e-calculators. Workstream 2 – in the PAtient-SPecific Oxygen monitoring to Reduce blood Transfusion during heart surgery (PASPORT) trial and a systematic review we demonstrated that personalised near-infrared spectroscopy-based algorithms for the optimisation of tissue oxygenation, or as indicators for red cell transfusion, were neither clinically effective nor cost-effective. Workstream 3 – in the REDWASH trial we failed to demonstrate a reduction in inflammation or organ injury in recipients of mechanically washed red cells compared with standard (unwashed) red cells.

Limitations

Existing studies evaluating the predictive accuracy or effectiveness of POC tests of coagulopathy or near-infrared spectroscopy were at high risk of bias. Interventions that alter red cell transfusion exposure, a common surrogate outcome in most trials, were not found to be clinically effective.

Conclusions

A systematic assessment of devices in clinical use as blood management adjuncts in cardiac surgery did not demonstrate clinical effectiveness or cost-effectiveness. The contribution of anaemia and coagulopathy to adverse clinical outcomes following cardiac surgery remains poorly understood. Further research to define the pathogenesis of these conditions may lead to more accurate diagnoses, more effective treatments and potentially improved clinical outcomes.

Study registration

Current Controlled Trials ISRCTN20778544 (COPTIC study) and PROSPERO CRD42016033831 (systematic review) (workstream 1); Current Controlled Trials ISRCTN23557269 (PASPORT trial) and PROSPERO CRD4201502769 (systematic review) (workstream 2); and Current Controlled Trials ISRCTN27076315 (REDWASH trial) (workstream 3).

Funding

This project was funded by the National Institute for Health Research (NIHR) Programme Grants for Applied Research programme and will be published in full inProgramme Grants for Applied Research; Vol. 5, No. 17. See the NIHR Journals Library website for further project information.

Preoperative hemoglobin level: the best predictor of transfusion of packed red cells

Blood transfusions could have serious consequences for patients. A reduction in the transfusion rate could be accomplished by an optimized blood management. Clear guidelines and awareness among all employees at a single institution have resulted in a reduction in transfusion rates in recent years. Identification of the group of patients who still received a blood transfusion in recent years could result in a further reduction. This study enrolled 4022 patients undergoing cardiothoracic surgery between 2008 and 2013. Patients were divided into three groups: “no blood transfusion”, “transfusion of packed red cells only” and “any other combinations of blood transfusion”. In total, 16 variables were tested for their association with the administration of homologous blood. The variables associated with blood transfusion were included in a stepwise multinomial logistic regression analysis to find the variables with the strongest association.

For the transfusion of packed red cells only and any other combinations of blood transfusion, the following predictors are found: gender, age, weight, type of surgery, reoperation, unstable angina pectoris, endocarditis, recent myocardial infarction, preoperative creatinine level, preoperative hemoglobin level and preoperative platelet count. The best predictor for the transfusion of packed red cells is preoperative hemoglobin level (4.1 to 7.8 mmol/l). For other blood products, the strongest association was found with type of surgery (aortic surgery, ventricular septal rupture and intracardiac tumour).

Postoperative Critical Care of the Adult Cardiac Surgical Patient. Part I: Routine Postoperative Care

OBJECTIVES

Cardiac surgery, including coronary artery bypass, cardiac valve, and aortic procedures, is among the most common surgical procedures performed in the United States. Successful outcomes after cardiac surgery depend on optimum postoperative critical care. The cardiac intensivist must have a comprehensive understanding of cardiopulmonary physiology and the sequelae of cardiopulmonary bypass. In this concise review, targeted at intensivists and surgeons, we discuss the routine management of the postoperative cardiac surgical patient.

DATA SOURCE AND SYNTHESIS

Narrative review of relevant English-language peer-reviewed medical literature.

CONCLUSIONS

Critical care of the cardiac surgical patient is a complex and dynamic endeavor. Adequate fluid resuscitation, appropriate inotropic support, attention to rewarming, and ventilator management are key components. Patient safety is enhanced by experienced personnel, a structured handover between the operating room and ICU teams, and appropriate transfusion strategies.

The operating surgeon is an independent predictor of chest tube drainage following cardiac surgery

OBJECTIVES

Bleeding into the chest is a major cause of blood transfusion and adverse outcomes following cardiac surgery. The authors investigated predictors of bleeding following cardiac surgery to identify potentially correctable factors.

DESIGN

Data were retrieved from the medical records of patients undergoing cardiac surgery over the period of 2002 to 2008. Multivariate analysis was used to identify the independent predictors of chest tube drainage.

SETTING

Tertiary hospital.

PARTICIPANTS

Two thousand five hundred seventy-five patients.

INTERVENTIONS

Cardiac surgery.

RESULTS

The individual operating surgeon was independently associated with the extent of chest tube drainage. Other independent factors included internal mammary artery grafting, cardiopulmonary bypass time, urgency of surgery, tricuspid valve surgery, redo surgery, left ventricular impairment, male gender, lower body mass index and higher preoperative hemoglobin levels. Both a history of diabetes and administration of aprotinin were associated with reduced levels of chest tube drainage.

CONCLUSIONS

The individual operating surgeon was an independent predictor of the extent of chest tube drainage. Attention to surgeon-specific factors offers the possibility of reduced bleeding, fewer transfusions, and improved patient outcomes.

Effect of severe left ventricular systolic dysfunction on hospital outcome after transcatheter aortic valve implantation or surgical aortic valve replacement: results from a propensity-matched population of the Italian OBSERVANT multicenter study

OBJECTIVE

Despite demonstration of the superior outcomes of transcatheter aortic valve implantation (TAVI) versus optimal medical therapy for severe left ventricular systolic dysfunction, studies comparing TAVI and surgical aortic valve replacement (AVR) in this high-risk group have been lacking.

METHODS

We performed propensity matching for age, gender, baseline comorbidities, previous interventions, priority at hospital admission, frailty score, New York Heart Association class, EuroSCORE, and associated cardiac diseases. Next, the 30-day mortality and procedure-related morbidity of 162 patients (81 TAVI vs 81 AVR) with severe left ventricular systolic dysfunction (ejection fraction ≤ 35%) were analyzed at the Italian National Institute of Health.

RESULTS

The 30-day mortality was comparable (P = .37) between the 2 groups. The incidence of periprocedural acute myocardial infarction (P = .55), low output state (P = .27), stroke (P = .36), and renal dysfunction (peak creatinine level, P = .57) was also similar between the 2 groups. TAVI resulted in significantly greater postprocedural permanent pacemaker implantation (P = .01) and AVR in more periprocedural transfusions (P < .01) despite a similar transfusion rate per patient (2.8 ± 3.7 for TAVI vs 4.4 ± 3.8 for AVR; P = .08). The postprocedural intensive care unit stay (median, 2 days after TAVI vs 3 days after AVR; P = .34), intermediate care unit stay (median, 0 days after both TAVI and AVR; P = .94), and hospitalization (median, 11 days after TAVI vs 14 days after AVR; P = .51) were comparable.

CONCLUSIONS

In patients with severe left ventricular systolic dysfunction, both TAVI and AVR are valid treatment options, with comparable hospital mortality and periprocedural morbidity. Comparisons of the mid- to long-term outcomes are mandatory.

Monitoring of brain oxygen saturation (INVOS) in a protocol to direct blood transfusions during cardiac surgery: a prospective randomized clinical trial

Background

Blood transfusions are common in cardiac surgery, but have been associated with increased morbidity and long-term mortality. Efforts to reduce blood product use during cardiac surgery include fluid restriction to minimize hemodilution, and protocols to guide transfusion decisions. INVOS is a modality that monitors brain tissue oxygen saturation, and could be useful in guiding decisions to transfuse. However, the role of INVOS (brain tissue oxygen saturation) as part of an algorithm to direct blood transfusions during cardiac surgery has not been evaluated. This study was conducted to investigate the value of INVOS as part of a protocol for blood transfusions during cardiac surgery.

Methods

Prospective, randomized, blinded clinical trial, on 150 (75 per group) elective cardiac surgery patients. The study was approved by the Institution Ethics committee and all patients gave written informed consent. Data were initially analyzed based on “intention to treat”, but subsequently were also analyzed “per protocol”.

Results

When protocol was strictly followed (“per protocol analysis”), compared to the control group, significantly fewer patients monitored with INVOS received any blood transfusions (46 of 70 patients in INVOS group vs. 55 of 67 patients in the control group, p = 0.029). Similarly, patients monitored with INVOS received significantly fewer units of red blood cell transfusions intraoperatively (0.20 ± 0.50 vs. 0.52 ± 0.88, p = 0.008) and overall during hospital stay (1.31 ± 1.20 vs. 1.82 ± 1.46, p = 0.024). When data from all patients (including patient with protocol violation) were analyzed together (“intention to treat analysis”), the observed reduction of blood transfusions in the INVOS group was still significant (51 of 75 patients transfused in the INVOS group vs. 63 of 75 patients transfused in the control group, p = 0.021), but the overall number of units transfused per patient did not differ significantly between the groups (1.55 ± 1.97 vs. 1.84 ± 1.41, p = 0.288).

Conclusions

Our data suggest that INVOS could be a useful tool as part of an algorithm to guide decisions for blood transfusion in cardiac surgery. Additional data from rigorous, well designed studies are needed to further evaluate the role of INVOS in guiding blood transfusions in cardiac surgery, and circumvent the limitations of this study.

Trial registration

ClinicalTrials.gov: NCT00879463

Is a cell saver necessary in off-pump coronary artery bypass surgery?

BACKGROUND

Off-pump coronary artery bypass surgery should have a significantly lower risk of postoperated bleeding than on-pump surgery. However, the use of a cell saver has been considered necessary, with significant additional cost incurred. Can we consider performing off-pump coronary artery bypass surgery without a cell saver?

PATIENTS AND METHODS

A prospective observational study was performed in 68 consecutive patients operated on for 2- or 3-vessel coronary lesions by the off-pump technique.

RESULTS

The mean number of distal anastomoses was 2.7 ± 0.7. Both internal thoracic arteries were used in 45 patients, and sequential revascularization was performed in 27, with 140 (77.8%) arterial grafts. Cell savers were used in 21 (30.9%) patients. In these 21 patients, the mean volume retransfused after treatment was 315 ± 177 mL. Postoperatively, 11 (16.2%) patients were transfused with packed red blood cells, with a mean volume of 636 ± 234 mL per patient. The 2 factors identified as associated with a higher risk of autotransfusion were female sex and a lower preoperative hemoglobin.

CONCLUSIONS

The use of a cell saver in off-pump surgery is useless in most cases. Careful surgical hemostasis is essential to limit hypovolemia.

Management of intraoperative fluid balance and blood conservation techniques in adult cardiac surgery

Blood transfusions are associated with adverse physiologic effects and increased cost, and therefore reduction of blood product use during surgery is a desirable goal for all patients. Cardiac surgery is a major consumer of donor blood products, especially when cardiopulmonary bypass (CPB) is used, because hematocrit drops precipitously during CPB due to blood loss and blood cell dilution. Advanced age, low preoperative red blood cell volume (preoperative anemia or small body size), preoperative antiplatelet or antithrombotic drugs, complex or re-operative procedures or emergency operations, and patient comorbidities were identified as important transfusion risk indicators in a report recently published by the Society of Cardiovascular Anesthesiologists. This report also identified several pre- and intraoperative interventions that may help reduce blood transfusions, including off-pump procedures, preoperative autologous blood donation, normovolemic hemodilution, and routine cell saver use.A multimodal approach to blood conservation, with high-risk patients receiving all available interventions, may help preserve vital organ perfusion and reduce blood product utilization. In addition, because positive intravenous fluid balance is a significant factor affecting hemodilution during cardiac surgery, especially when CPB is used, strategies aimed at limiting intraoperative fluid balance positiveness may also lead to reduced blood product utilization.This review discusses currently available techniques that can be used intraoperatively in an attempt to avoid or minimize fluid balance positiveness, to preserve the patient's own red blood cells, and to decrease blood product utilization during cardiac surgery.

Preoperative fibrinogen plasma concentration is associated with perioperative bleeding and transfusion requirements in scoliosis surgery

STUDY DESIGN

Prospective observational study.

OBJECTIVE

To investigate the potential association between fibrinogen, bleeding, and transfusion requirements after scoliosis surgery.

SUMMARY OF BACKGROUND DATA

Bleeding complications during and after orthopedic surgery are associated with increased morbidity and mortality. Early identification of patients with increased risk of excessive bleeding offers the possibility to initiate countermeasures. Fibrinogen is a key protein in the coagulation cascade, and thus a potential biomarker for bleeding risk.

METHODS

A total of 82 otherwise healthy patients (mean age: 15 ± 3 years, 85% girls) undergoing surgery for adolescent idiopathic scoliosis were included in the study. Patient variables (age, gender, operation time, and thrombosis prophylaxis), preoperative laboratory variables (hemoglobin, platelet count, activated partial thromboplastin time [aPTT], prothrombin time [PT], and fibrinogen), peroperative and postoperative bleeding volume, and transfusions were registered. Correlations between laboratory variables and bleeding volume were calculated with Pearson test. Patient variables and laboratory variables were compared with Student t test between patients with bleeding volume in the upper quartile ("bleeders") and the remaining patients, and between patients with extensive transfusion (defined as >2 U of packed red cells) and no or limited transfusions (≤ 2 U).

RESULTS

Mean fibrinogen concentration was 3.0 ± 0.7 g/L (range, 1.3- 4.9). Mean total perioperative bleeding volume was 1552 ± 1019 mL (range, 100-5800 mL). Total bleeding volume correlated significantly with preoperative fibrinogen concentration (r = -0.31, P = 0.005) but neither with platelet count, aPTT, nor PT (P = 0.61, 0.46, and 0.57, respectively). Bleeders had significantly lower preoperative fibrinogen plasma concentration (2.6 ± 0.6 vs. 3.1 ± 0.6 g/L, P = 0.002). Of total, 16% (13/82) of the patients were transfused with >2 U of packed red cells. Patients with extensive transfusions had significantly lower preoperative fibrinogen plasma concentration (2.5 ± 0.7 vs. 3.1 ± 0.6 g/L, P = 0.002), while preoperative platelet count, aPTT, and PT did not differ.

CONCLUSION

The results indicate that preoperative fibrinogen concentration is a limiting factor for postoperative hemostasis during and after scoliosis surgery. Preoperative measurement of fibrinogen concentration provides more information about bleeding volume and transfusion requirements than standard screening tests.

Blood transfusion is associated with prolonged duration of mechanical ventilation in infants undergoing reparative cardiac surgery

OBJECTIVE

Perioperative transfusion has adverse effects in adults undergoing cardiac surgery. We sought to investigate whether greater use of blood and blood products might be an independent predictor of prolonged postoperative recovery, indicated by duration of mechanical ventilation (DMV), after reparative infant heart surgery.

DESIGN

Secondary analysis of prospectively collected data from two randomized trials of hematocrit strategy during cardiopulmonary bypass in infant heart surgery to explore the association of DMV with perioperative transfusion and other variables.

SETTING

Tertiary pediatric hospital.

PATIENTS

Two hundred seventy infants undergoing two ventricle corrective cardiac surgery without aortic arch reconstruction.

MEASUREMENTS AND MAIN RESULTS

In univariable analyses, longer DMV was associated with younger age and lower weight at surgery, diagnostic group, and higher intraoperative and postoperative blood product transfusion (each p < .001). In multivariable proportional hazard regression, longer total support time and greater intraoperative and early postoperative blood products per kg were the strongest predictors of longer DMV. Patients in the highest tertile of intraoperative blood products per kg had an instantaneous risk of being extubated approximately half that of patients in the lowest tertile (hazard ratio, 0.51; 95% confidence interval, 0.35, 0.73). Patients who received any blood products on postoperative day 1, compared with those who did not, had a hazard ratio for extubation of 0.65 (95% confidence interval, 0.50, 0.85).

CONCLUSIONS

In this exploratory secondary analysis of infants undergoing two ventricular repair of congenital heart disease without aortic arch obstruction, greater intraoperative and early postoperative blood transfusion emerged as potential important risk factors for longer DMV. Future prospective clinical trials are needed to determine whether reduction in blood product administration hastens postoperative recovery after infant heart surgery.

Effects of fibrinogen concentrate administration during severe hemorrhage

BACKGROUND

Fibrinogen concentrate has been shown to improve coagulation in dilutional coagulopathy in experimental studies, but clinical experience is still scarce. The aim of this study was to evaluate laboratory data and the clinical outcome of fibrinogen administration in patients suffering from severe hemorrhage.

MATERIALS AND METHODS

A retrospective study over a 3-year observation period of consecutive patients who received a single dose of fibrinogen concentrate but not recombinant factor VIIa as part of their treatment of severe hemorrhage, defined as >6 U of packed red blood cells (PRBCs).

RESULTS

Thirty-seven patients were included, most of them suffering from severe hemorrhage following open heart surgery (68%). After a median fibrinogen dose of 2 g (range 1-6 g), an absolute increase in the plasma fibrinogen concentration of 0.6 g/l was observed (P<0.001). The activated partial thromboplastin time (APTT) decreased significantly (P<0.001), from 52 to 43 s and the prothrombin time (PT) decreased from 20 to 17 s, respectively. The transfusion requirement for PRBCs decreased from 6 to 3 U (P<0.01) in the 24 h after fibrinogen administration, but fresh-frozen plasma and platelet concentrate transfusions did not change significantly. Eight patients (22%) died in intensive care unit and the pre-operative fibrinogen concentration was not significantly different in these patients.

CONCLUSION

Administration of fibrinogen for severe hemorrhage was associated with an increased fibrinogen concentration and a significant decrease in APTT, PT and the requirement for PRBCs.

Intra-operative intravenous fluid restriction reduces perioperative red blood cell transfusion in elective cardiac surgery, especially in transfusion-prone patients: a prospective, randomized controlled trial

BACKGROUND

Cardiac surgery is a major consumer of blood products, and hemodilution increases transfusion requirements during cardiac surgery under CPB. As intraoperative parenteral fluids contribute to hemodilution, we evaluated the hypothesis that intraoperative fluid restriction reduces packed red-cell (PRC) use, especially in transfusion-prone adults undergoing elective cardiac surgery.

METHODS

192 patients were randomly assigned to restrictive (group A, 100 pts), or liberal (group B, 92 pts) intraoperative intravenous fluid administration. All operations were conducted by the same team (same surgeon and perfusionist). After anesthesia induction, intravenous fluids were turned off in Group A (fluid restriction) patients, who only received fluids if directed by protocol. In contrast, intravenous fluid administration was unrestricted in group B. Transfusion decisions were made by the attending anesthesiologist, based on identical transfusion guidelines for both groups.

RESULTS

137 of 192 patients received 289 PRC units in total. Age, sex, weight, height, BMI, BSA, LVEF, CPB duration and surgery duration did not differ between groups. Fluid balance was less positive in Group A. Fewer group A patients (62/100) required transfusion compared to group B (75/92, p < 0.04). Group A patients received fewer PRC units (113) compared to group B (176; p < 0.0001). Intraoperatively, the number of transfused units and transfused patients was lower in group A (31 u in 19 pts vs. 111 u in 62 pts; p < 0.001). Transfusions in ICU did not differ significantly between groups. Transfused patients had higher age, lower weight, height, BSA and preoperative hematocrit, but no difference in BMI or discharge hematocrit. Group B (p < 0.005) and female gender (p < 0.001) were associated with higher transfusion probability. Logistic regression identified group and preoperative hematocrit as significant predictors of transfusion.

CONCLUSIONS

Our data suggest that fluid restriction reduces intraoperative PRC transfusions without significantly increasing postoperative transfusions in cardiac surgery; this effect is more pronounced in transfusion-prone patients.

TRIAL REGISTRATION

NCT00600704, at the United States National Institutes of Health.

Perioperative Coagulopathy, Bleeding, and Hemostasis During Cardiac Surgery

Cardiac surgery patients use 10%-25% of the blood products transfused annually in the United States. The transfusion of red blood cells or blood products has been the subject of intense scrutiny over the past 10 years. Bleeding after cardiac surgery can be surgical or nonsurgical and lead to hemodynamic compromise and surgical reexploration. Because hemorrhage and blood product transfusions are associated with multiple negative outcomes, including increased mortality, it is prudent to understand the mechanisms responsible for nonsurgical bleeding. This review focuses on the physiology of the normal coagulation and fibrinolysis, risk factors associated with patients presenting for cardiac surgery, impairments of normal hemostasis associated with cardiac surgery and cardiopulmonary bypass (CPB), and potential interventions to reduce perioperative blood loss and blood transfusion.

Coagulation and fibrinolytic protein kinetics in cardiopulmonary bypass

The development of Cardiopulmonary Bypass (CPB) catopulted the field of cardiothoracic surgery into a new dimension--one that changed the lives of individuals with congenital and acquired heart disease worldwide. Despite its contributions, CPB has clear limitations and creates unique challenges for clinicians and patients alike, stemming from profound hemostatic pertubations and accompanying risk for bleeding and possibly thrombotic complications.

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.

A Comparison of Bilateral with Single Internal Mammary Artery Grafts on Postoperative Mediastinal Drainage and Transfusion Requirement

The superiority of the left internal mammary artery (LIMA) graft over autogenous saphenous vein as a bypass conduit in coronary artery bypass surgery has been well established. Early and late patency rates of bilateral internal mammary artery (BIMA) grafts exceed those of vein grafts, and patients who receive BIMA have improved long-term survival rates and more freedom from reoperations and other cardiac events. But because of other concerns, particularly the question of increased risk of postoperative bleeding, controversy still surrounds the perioperative period. In the present study we sought to determine whether BIMA grafting was an independent risk factor of postoperative bleeding and of blood product use in patients undergoing primary elective coronary artery revascularization. For this purpose, 33 consecutive patients scheduled for BIMA grafting were matched with 66 patients operated on by single LIMA grafting. Patients in the LIMA group had significantly less postoperative mediastinal drainage than those in the BIMA group (median: 722 vs 920 mL, P = 0.0001). Fifty-six patients received blood products (56% vs 51% in LIMA and BIMA groups, respectively; P = 0.67). In multivariate analysis, BIMA and operative duration were independent predictors of increased postoperative drainage. Nevertheless, in logistic regression, BIMA was not significantly associated with blood product use, unlike precardiopulmonary bypass hematocrit and duration of surgery (OR and 95% CI: 0.89 [0.80-0.96] P = 0.01; 1.009 [1.001-1.019] P = 0.04, for an increase of 1% in hematocrit and 1 min in duration of surgery, respectively). In conclusion, these data support the idea that BIMA graft slightly increases postoperative drainage but not transfusion requirement.

Indications for Blood Transfusion in Cardiac Surgery

In addition to its life-saving effect in hemorrhagic shock, transfusion of allogenic packed red blood cells can be beneficial in situations where a critically low hematocrit is contributing to a state of oxygen-supply dependency. These benefits are countered by the risks of transfusion-associated lung injury, transfusion-associated immunomodulation, and cellular hypoxia after RBC transfusion. The critical hematocrit is patient and organ specific, and varies intraoperatively according to the duration and temperature of bypass, as well as for a variable postoperative period. Future randomized studies must prospectively evaluate regional indicators of tissue oxygenation in transfusion algorithms.

A randomized trial of tranexamic acid in combination with cell salvage plus a meta-analysis of randomized trials evaluating tranexamic acid in off-pump coronary artery bypass grafting

OBJECTIVES

We sought to evaluate the effectiveness of tranexamic acid in off-pump coronary artery bypass grafting surgery, either when used in combination with mechanical cell salvage or when used alone.

METHODS

One hundred patients were randomized to either 2 g of tranexamic acid as an intravenous bolus before sternotomy or to placebo. Intraoperative and postoperative cell salvage was used in all patients. The primary end point was early postoperative blood loss (within 4 hours). To evaluate the efficacy of tranexamic acid in isolation, we also performed a meta-analysis of 4 randomized trials identified from a systematic literature search. The primary end point of the meta-analysis was red cell transfusion.

RESULTS

In our randomized trial patients in the tranexamic acid group had a significant reduction in early postoperative blood loss, (median difference, 50 mL; 95% confidence interval, 15-100 mL; P < .01); however, there was no reduction in the frequency of blood component transfusion. Patients in the placebo group received a significantly larger volume of autotransfused red cells (median difference, 120 mL; 95% confidence interval, 0-220 mL; P = .02). The meta-analysis demonstrated a significant reduction in red cell transfusions in patients receiving tranexamic acid compared with those receiving placebo (risk ratio, 0.48; 95% confidence interval, 0.24-0.97; P = .041). There was also a reduction in the frequency of any allogeneic blood component transfusion, as well as a highly significant reduction in postoperative blood loss, in patients receiving tranexamic acid (P < .001).

CONCLUSIONS

Tranexamic acid reduces blood loss and transfusion requirements in off-pump coronary artery bypass grafting surgery. A reduction in allogeneic blood transfusion was not evident in the presence of perioperative cell salvage. These data support the routine use of tranexamic acid in off-pump coronary artery bypass grafting surgery.

Determinants of complications with recombinant factor VIIa for refractory blood loss in cardiac surgery

PURPOSE

Recombinant factor VIIa (rFVIIa) is being used for refractory, excessive blood loss (EBL) after cardiac surgery, but its safety for this indication is not known.

METHODS

The unadjusted and risk-adjusted adverse event (AE) rates were compared between 114 consecutive cardiac surgical patients who received rFVIIa for refractory EBL and 541 concurrent patients who developed EBL but did not receive rFVIIa. Similarly, timing of rFVIIa therapy was assessed by dichotomizing rFVIIa patients based on median number of red blood cell (RBC) units received before therapy. The measured AE was a composite of death, stroke, renal failure, myocardial infarction, and major vein thrombosis. For risk adjustment, logistic regression models for this outcome were constructed using known predictors of AEs.

RESULTS

The median RBC units transfused before rFVIIa therapy was eight. The AE rates in the untreated, early (< or = 8 U), and late (> 8 U) treated patients were 24% (129/541), 30% (20/66), and 60% (29/48). The risk-adjustment model included total RBC units, pump time, weaning difficulty, gender, weight, and age. The unadjusted and adjusted AE odds ratios (OR) in the treated vs untreated groups were 2.41 [confidence interval (CI) 1.58-3.67; P < 0.0001] and 1.04 (CI 0.60-1.81; P = 0.9). In the rFVIIa group, the adjusted AE OR was lower in the early treated group (OR 0.41; CI 0.18-0.92; P = 0.03).

CONCLUSION

In cardiac surgical patients with refractory hemorrhage, rFVIIa therapy is not associated with increased risk of AEs, and early treatment may be associated with better outcomes.

Prediction of massive blood transfusion in cardiac surgery

PURPOSE

In cardiac surgery with cardiopulmonary bypass (CPB), excessive blood loss requiring the transfusion of multiple red blood cell (RBC) units is a common complication that is associated with significant morbidity and mortality. The objective of this study was to develop a prediction rule for massive blood transfusion (MBT) that could be used to optimize the management of, and research on, at-risk patients.

METHODS

Data were collected prospectively over the period from 2000 to 2005, on patients who underwent surgery with CPB at one hospital. Patients who received > or = five units of RBC within one day of surgery were classified as MBT. Logistic regression was used to appropriately select and weigh perioperative variables in the prediction rule, which was developed on the initial 60% of the sample and validated on the remaining 40%.

RESULTS

Of the 10,667 patients included, 925 (8.7%) had MBT. The clinical prediction rule included 12 variables (listed in order of predictive value: CPB duration, preoperative hemoglobin concentration, body surface area, nadir CPB hematocrit, previous sternotomy, preoperative shock, preoperative platelet count, urgency of surgery, age, surgeon, deep hypothermic circulatory arrest, and type of procedure) and was highly discriminative (c-index = 0.88). In the validation set, those classified as low-, moderate-, and high-risk by a simple risk score derived from the prediction rule had a 5%, 27%, and 58% chance of MBT, respectively.

CONCLUSION

A clinical prediction rule was developed that accurately identified patients at low-risk or high-risk for MBT. Studies are needed to determine the external generalizability and clinical utility of the prediction rule.