Hematologic evaluation of intraoperative autologous blood collection and allogeneic transfusion in cardiac surgery

Acute normovolemic hemodilution in cardiac surgery: Rationale and design of a multicenter randomized trial

BACKGROUND

Minimizing the use of blood component can reduce known and unknown blood transfusion risks, preserve blood bank resources, and decrease healthcare costs. Red Blood Cell (RBC) transfusion is common after cardiac surgery and associated with adverse perioperative outcomes, including mortality. Acute normovolemic hemodilution (ANH) may reduce bleeding and the need for blood product transfusion after cardiac surgery. However, its blood-saving effect and impact on major outcomes remain uncertain.

METHODS

This is a single-blinded, multinational, pragmatic, randomized controlled trial with a 1:1 allocation ratio conducted in Tertiary and University hospitals. The study is designed to enroll patients scheduled for elective cardiac surgery with planned cardiopulmonary bypass (CPB). Patients are randomized to receive ANH before CPB or the best available treatment without ANH. We identified an ANH volume of at least 650 ml as the critical threshold for clinically relevant benefits. Larger ANH volumes, however, are allowed and tailored to the patient's characteristics and clinical conditions.

RESULTS

The primary outcome is the percentage of patients receiving RBCs transfusion from randomization until hospital discharge, which we hypothesize will be reduced from 35% to 28% with ANH. Secondary outcomes are all-cause 30-day mortality, acute kidney injury, bleeding complications, and ischemic complications.

CONCLUSION

The trial is designed to determine whether ANH can safely reduce RBC transfusion after elective cardiac surgery with CPB.

STUDY REGISTRATION

This trial was registered on ClinicalTrials.gov in April 2019 with the trial identification number NCT03913481.

Effect of acute normovolemic hemodilution in patients undergoing cardiac surgery with remimazolam anesthesia

PURPOSE

The reduced effects of allogeneic transfusion with acute normovolemic hemodilution (ANH) have been reported. Harvesting a large volume of blood may maximize the effect in patients with low body weight, and the prevention of hypotension is important. Remimazolam is an anesthetic with few circulatory responses. Our aim was to evaluate whether high-volume ANH reduces the need for transfusion in cardiac patients under remimazolam anesthesia.

METHODS

In this retrospective single-center study, we enrolled cardiopulmonary bypass (CPB) patients who received remimazolam anesthesia. Changes in hemodynamic parameters were assessed. The numbers of blood transfusions and chest tube outputs were also evaluated.

RESULTS

In a total of 51 patients, ANH was performed in 27 patients with a mean body mass index of 23.2 (ANH volume: 740 ± 222 mL). No significant differences were observed in mean blood pressure during blood collection. The intraoperative amount of red blood cell (RBC) transfusion was significantly lower in the ANH group than in the control group (431 ± 678 and 1260 ± 572 mL, p < 0.001). The avoidance rates of RBC were 66.7 and 4.2%, respectively. The multivariate analysis result revealed that ANH correlated with RBC, with an odds ratio of 0.067 (95% confidence interval 0.005-0.84, p < 0.05). The postoperative bleeding at 24 h was significantly lower in the ANH group (455 ± 228 and 797 ± 535 mL, p < 0.01).

CONCLUSION

In patients undergoing CPB, ANH reduced intraoperative transfusion amount and postoperative bleeding. Hemodynamic changes during blood collection were minimal under remimazolam anesthesia and high-volume ANH was feasible.

Large volume acute normovolemic hemodilution in patients undergoing cardiac surgery with intermediate-high risk of transfusion: A randomized controlled trial

STUDY OBJECTIVE

To investigate whether large volume acute normovolemic hemodilution (L-ANH), compared with moderate acute normovolemic hemodilution (M-ANH), can reduce perioperative allogeneic blood transfusion in patients with intermediate-high risk of transfusion during cardiac surgery with cardiopulmonary bypass (CPB).

DESIGN

Prospective randomized controlled trial.

SETTING

University hospital.

PATIENTS

Patients with transfusion risk understanding scoring tool ("TRUST") ≥2 points undergoing cardiac surgery with CPB in the Second Affiliated Hospital of Zhejiang University from May 2020 to January 2021 were included.

INTERVENTIONS

The patients were randomly assigned with a 1:1 ratio to M-ANH (5 to 8 mL/kg) or L-ANH (12 to 15 mL/kg).

MEASUREMENTS

The primary outcome was perioperative red blood cell (RBC) transfusion units. The composite outcome included new-onset atrial fibrillation, pulmonary infection, cardiac surgery associated acute kidney injury (CSA-AKI) class ≥2, surgical incision infection, postoperative excessive bleeding, and resternotomy.

MAIN RESULTS

Total 159 patients were screened and 110 (55 L-ANH and 55 M-ANH) were included for final analysis. Removed blood volume of L-ANH is significantly higher than M-ANH (886 ± 152 vs. 395 ± 86 mL, P < 0.001). Perioperative RBC transfusion was median 0 unit ([25th, 75th] percentiles: 0-4.4) in M-ANH group vs. 0 unit ([25th, 75th] percentiles: 0-2.0) in L-ANH group (P = 0.012) and L-ANH was associated with lower incidence of transfusion (23.6% vs. 41.8%, P = 0.042, rate difference: 0.182, 95% confidence interval [0.007-0.343]). The incidence of postoperative excessive bleeding was significantly lower in L-ANH vs. M-ANH (3.6% vs. 18.2%, P = 0.029, rate difference: 0.146, 95% confidence interval [0.027-0.270]) without significant difference for other second outcomes. The volume of ANH was inversely related to perioperative RBC transfusion units (Spearman r = -0.483, 95% confidence interval [-0.708 to -0.168], P = 0.003), and L-ANH in cardiac surgery was associated with a significantly reduced risk of perioperative RBC transfusion (odds ratio: 0.43, 95% confidence interval: 0.19-0.98, P = 0.044).

CONCLUSIONS

Compared with M-ANH, L-ANH during cardiac surgery inclined to be associated with reduced perioperative RBC transfusion and the volume of RBC transfusion was inversely proportional to the volume of ANH. In addition, LANH during cardiac surgery was associated with a lower incidence of postoperative excessive bleeding.

Viscoelastic Management of Coagulopathy during the Perioperative Period of Liver Transplantation

Viscoelastic testing (VET) in liver transplantation (LT) has been used since its origin, in combination with standard laboratory testing (SLT). There are only a few, small, randomized controlled trials that demonstrated a reduction in transfusion rates using VET to guide coagulation management. Retrospective analyses contrasting VET to SLT have demonstrated mixed results, with a recent concern for overtreatment and the increase in postoperative thrombotic events. An oversight of many studies evaluating VET in LT is a single protocol that does not address the different phases of surgery, in addition to pre- and postoperative management. Furthermore, the coagulation spectrum of patients entering and exiting the operating room is diverse, as these patients can have varying anatomic and physiologic risk factors for thrombosis. A single transfusion strategy for all is short sighted. VET in combination with SLT creates the opportunity for personalized resuscitation in surgery which can address the many challenges in LT where patients are at a paradoxical risk for both life-threatening bleeding and clotting. With emerging data on the role of rebalanced coagulation in cirrhosis and hypercoagulability following LT, there are numerous potential roles in VET management of LT that have been unaddressed.

Modified cardiopulmonary bypass with low priming volume for blood conservation in cardiac valve replacement surgery

BACKGROUND

The adverse effects of cardiopulmonary bypass during open cardiac surgery, including hemodilution, seem to be inevitable, especially for patients who generally have a relatively lower BMI with relatively small blood volumes. This study reports the modification and use of a cardiopulmonary bypass (CPB) system to reduce priming volume and hemodilution.

METHODS

This is a retrospective study of 462 adult patients who underwent cardiac valve replacement surgery from January 2019 to September 2021 at the General Hospital of Western Theater Command. The modified group consisted of 212 patients undergoing modified CPB. The control group included 250 patients receiving conventional CPB. Evaluated indices included fluid intake and output volumes during CPB, intraoperative indices related to CPB operation, usage of blood products during the peri-CPB period, and postoperative outcomes.

RESULTS

The modified group displayed a significant reduction in the crystalloid (200 mL vs. 600 mL, P < 0.05) and colloid priming volumes (450 mL vs. 1100 mL, P < 0.05), and ultrafiltration solution volume (750 mL vs. 1200 mL, P < 0.05). Furthermore, the modified group had a significantly lower rate of defibrillation (30.2% vs. 41.2%, P < 0.05). The intraoperative urine volume (650 mL vs. 500 mL, P < 0.05) and intraoperative hematocrit (Hct) (26% vs. 24%, P < 0.05) of the modified CPB group were also higher than in the control group. The modified group required a lower infusion volume of packed red blood cells (250 mL vs. 400 mL, P < 0.05) and lower infusion rates of packed red blood cells (17.9% vs. 25.2%, P < 0.05) and fresh frozen plasma (1.41% vs. 5.2%, P < 0.05). In addition, the modified group showed significantly improved indices related to postoperative recovery.

CONCLUSIONS

The modified CPB system effectively conserves blood and shows noteworthy potential for application in cardiac valve replacement surgery.

Impact of Preoperative Hematocrit, Body Mass Index, and Red Cell Mass on Allogeneic Blood Product Usage in Adult Cardiac Surgical Patients: Report From a Statewide Quality Initiative

OBJECTIVE

The study aims were to evaluate current blood transfusion practice in cardiac surgical patients and to explore associations between preoperative anemia, body mass index (BMI), red blood cell (RBC) mass, and allogeneic transfusion.

DESIGN

Multicenter retrospective study.

SETTING

Academic and non-academic centers.

PARTICIPANTS AND INTERVENTIONS

After Institutional Review Board approval, 26,499 patients who underwent coronary artery bypass grafting ± valve replacement/repair between 2011 and 2019 were included from the Maryland Cardiac Surgery Quality Initiative database. Patients were stratified into BMI categories (<25, 25 to <30, and ≥30 kg/m²), and a multivariable logistic regression model was fit to determine if preoperative hematocrit, BMI, and RBC mass were associated independently with allogeneic transfusion.

RESULTS

Preoperative anemia was found in 55.4%, and any transfusion was administered to 49.3% of the entire cohort. Females and older patients had lower BMI and RBC mass. Increased RBC and cryoprecipitate transfusions occurred more frequently after surgery in the lower BMI group. After adjustments, increased transfusion was associated with a BMI <25 relative to a BMI ≥30 at an odds ratio (OR) of 1.26 (95% confidence interval [CI]: 1.08-1.39). For each 1% increase in preoperative hematocrit, transfusion was decreased by 9% (OR: 0.91; 95% CI: 0.90-0.92). For every 500 mL increase in RBC mass, there was a 43% reduction of transfusion (OR: 0.57; 95% CI: 0.55-0.58).

CONCLUSIONS

Transfusion probability modeling based on calculated RBC mass eliminated sex differences in transfusion risk based on preoperative hematocrit, and may better delineate which patients may benefit from more rigorous perioperative blood conservation strategy.

Management of Combined Cardiac Surgery Using Cardiopulmonary Bypass With Acute Normovolemic Hemodilution in a Jehovah's Witness: A Case Report

Combined cardiac surgery under cardiopulmonary bypass (CPB) has a high risk of requiring blood transfusion. Performing this surgery on Jehovah's Witnesses (JWs) is challenging as they strictly refuse allogeneic blood transfusions due to their religious beliefs. A 73-year-old female JW patient underwent combined surgery involving coronary artery bypass grafting and mitral valvuloplasty under CPB. Preoperative hematopoiesis maintained the hemoglobin (Hb) level at >12 g/dL preoperatively; the Hb level was maintained at >7 g/dL during CPB for effective acute normovolemic hemodilution (ANH). Compared with the values obtained immediately after CPB weaning, the Hb level and coagulation functions (measured using viscoelastic tests) improved after autologous transfusion at the end of the surgery. When cardiac surgery under CPB is performed on JWs, ANH can be useful for maintaining postoperative Hb levels and coagulation factors. Sufficient preoperative hematopoiesis and determination of an appropriate volume for intraoperative ANH may be important for effective ANH.

Citric acid-mediated green synthesis of selenium nanoparticles: antioxidant, antimicrobial, and anticoagulant potential applications

Using microwave technique in the presence of citric acid, selenium nanoparticles (SeNPs) were fabricated. The morphological characteristics revealed that the spherical SeNPs with diameters ranging from 10.5 to 20 nm aggregated spherical shapes with sizes ranging from 0.67 to 0.83 mm. Moreover, the antioxidant efficacy was assessed by the DPPH radical scavenging test, which depicted that green-prepared nanoparticle at a 106.3 mg/mL dosage had the maximum scavenging capacity (301.1 ± 11.42 mg/g). Otherwise, with nanoparticle concentrations of 500 mg/ml, in vitro cell viability of SeNPs through human breast cancer MCF-7 cell lines was reduced to 61.2 ± 2.2% after 1 day of exposure. The antibacterial activity was tested against G-negative Pseudomonas aeruginosa (P. aeruginosa) and Escherichia coli (E. coli), G-positive bacteria Bacillus subtilis (B. subtilis), and Staphylococcus aureus (S. aureus), which demonstrated that SeNPs had little activity against S. aureus. Still, it had the highest activity against E. coli, with a zone of inhibition (ZOI) of 25.2 ± 1.5 mm compared to 16.0 ± 0.6 mm for the standard antibiotic. Most notably, biogenic SeNPs have anticoagulant activities using activated partial thromboplastin time (aPTT) assessment. Based on previous findings, SeNPs can be used in medical aid and their cell viability, antioxidant, anticoagulant, and effects on bacteria.

Hemodilution in high-risk cardiac surgery: Laboratory values, physiological parameters, and outcomes

BACKGROUND

Acute normovolemic hemodilution (ANH) is a blood conservation strategy in cardiac surgery, predominantly used in coronary artery bypass graft (CABG) and/or valve procedures. Although higher complexity cardiac procedures may benefit from ANH, concerns for hemodynamic instability, and organ injury during hemodilution hinder its wider acceptance. Laboratory and physiological parameters during hemodilution in complex cardiac surgeries have not been described.

STUDY DESIGN AND METHODS

This observational cohort (2019-2021) study included 169 patients who underwent thoracic aortic repair, multiple valve procedure, concomitant CABG with the aforementioned procedure, and/or redo sternotomies. Patients who received allogeneic blood were excluded. Statistical comparisons were performed between ANH (N = 66) and non-ANH controls (N = 103). ANH consisted of removal of blood at the beginning of surgery and its return after cardiopulmonary bypass.

RESULTS

Intraoperatively, the ANH group received more albumin (p = .04) and vasopressor medications (p = .01), while urine output was no different between ANH and controls. Bilateral cerebral oximetry (rSO₂ ) values were similar before and after hemodilution. During bypass, rSO₂ were discretely lower in the ANH versus control group (right rSO₂ p = .03, left rSO₂ p = .05). No differences in lactic acid values were detected across the procedural continuum. Postoperatively, no differences in extubation times, intensive care unit length of stay, kidney injury, stroke, or infection were demonstrated.

DISCUSSION

This study suggests hemodilution to be a safe and comparable blood conservation technique, even without accounting for potential benefits of reduced allogenic blood administration. The study may contribute to better understanding and wider acceptance of ANH protocols in high-risk cardiac surgeries.

In vitro effects of emicizumab on activated clotting time in blood samples from cardiac surgical patients

BACKGROUND

Heparin management in hemophilia A (HA) patients with a factor VIII (FVIII) inhibitor can be challenging due to severe activated clotting time (ACT) prolongations. It is important to better understand the impact of emicizumab, a FVIII mimetic on ACT, and tissue factor (TF)-based coagulation assays.

METHODS

Whole blood from 18 patients undergoing cardiopulmonary bypass (CPB) were mixed in vitro with pooled normal plasma, FVIII-deficient or FVIII-inhibitor plasma to affect functional FVIII levels. ACTs and heparin concentration by protamine titration were measured in whole blood mixture with/without emicizumab (50-100 μg/ml). Thrombin generation and plasmin generation were measured in the patient's plasma mixed with normal plasma or FVIII-inhibitor plasma to assess the impact of emicizumab under low TF activation.

RESULTS

FVIII inhibitors prolonged ACTs by 2.2-fold compared to those in normal plasma mixture at baseline. During CPB, ACTs in normal plasma mixture, and FVIII-deficient mixture were in 400s, but ACTs reached 900s in FVIII-inhibitor mixture. Emicizumab shortened ACTs by up to 100s in normal plasma mixture, and FVIII-deficient mixtures. ACTs remained over 600s in FVIII-inhibitor mixture, despite adding emicizumab at 100 μg/ml. Heparin concentration measured by TF-based protamine titration was unaffected. Emicizumab enhanced thrombin peak in the presence of FVIII inhibitors, whereas plasmin generation was mainly affected by thrombin generation, and systemic use of ɛ-aminocaproic acid.

CONCLUSIONS

FVIII inhibitors extensively prolong ACTs in heparinized whole blood, and clinical levels of emicizumab partially reverse ACT values. Protamine titration should be considered for optimal heparin monitoring in emicizumab-treated patients with FVIII inhibitors.

The Year in Coagulation: Selected Highlights from 2020

This is the second annual review in the Journal of Cardiothoracic and Vascular Anesthesia to cover highlights in coagulation for cardiac surgery. The goal of this article is to provide readers with a focused summary from the literature of the prior year's most important coagulation topics. In 2020, this included a discussion covering allogeneic transfusion, antiplatelet and anticoagulant therapy, factor concentrates, coagulation testing, mechanical circulatory support, and the effects of coronavirus disease 2019.