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.

An in vitro study of coagulation evaluation in obstetric hemorrhage for pregnancy-induced hypertension with coagulation and platelet function analyzer.

This study aimed to establish in vitro hemodilution and resupplementation assays for obstetric hemorrhage in pregnancy-induced hypertension (PIH) and to monitor the coagulation function dynamically using a coagulation and platelet function analyzer. Forty-seven singleton pregnant women were divided into normal (n = 24) and PIH (n = 23) groups. Peripheral blood samples were used to construct the assays, and the activated clotting time (ACT), clotting rate (CR), and platelet function index (PF) were measured. The results showed that the baseline ACT was higher in the PIH group (p < 0.01). Hemodilution assays showed decreased ACT and increased CR and PF, with ACT changes significantly lower in the PIH group (p < 0.05). CR changed most in both groups at lower dilution ratios (35% to 50%), while ACT changed most at a higher dilution ratio (75%). In the resupplementation assay, ACT exhibited the most significant response. The analyzer effectively detected differences between pregnant women with and without PIH. Thus, we need to pay more attention to the changes of ACT in the actual clinical application to assess the coagulation status of parturients.

Clinical importance of distinguishing true anemia from dilutional pseudo-anemia: Consequences of a 3-year follow-up volume assessment in a heart failure patient.

In chronic heart failure, dilutional anemia and hypervolemia may occur due to plasma volume expansion, the latter sometimes exacerbated by an increase in red cell volume. Diagnosis and a therapeutic strategy require determination of vascular volumes.

Effects of acute normovolemic hemodilution and allogeneic blood transfusion on postoperative complications of oral and maxillofacial flap reconstruction: a retrospective study.

OBJECTIVE: Patients undergoing oral and maxillofacial flap reconstruction often need blood transfusions due to massive blood loss. With the increasing limitations of allogeneic blood transfusion (ABT), doctors are considering acute normovolemic hemodilution (ANH) because of its advantages. By comparing the differences in the (Δ) blood indices and postoperative complications of patients receiving ABT or ANH during the reconstruction and repair of oral and maxillofacial tumor flaps, this study's purpose was to provide a reference for the clinical application of ANH. METHODS: The clinical data of 276 patients who underwent oral and maxillofacial flap reconstruction from September 25, 2017, to October 11, 2021, in the Department of Oral and Maxillofacial Surgery, Sun Yat-sen Memorial Hospital, were retrospectively analyzed. According to the intraoperative blood transfusion mode, the patients were divided into two groups: ABT and ANH. The differences in the (Δ) blood indices and the incidence of postoperative complications between the groups were analyzed. RESULTS: Among the 276 patients who had ANH (124/276) and ABT (152/276), there were no differences in (Δ) Hb, (Δ) PT, or (Δ) FIB (P > 0.05), while (Δ) WBC, (Δ) PLT, (Δ) APTT and (Δ) D-dimer were significantly different (P < 0.05). The blood transfusion method was not an independent factor for flap crisis (P > 0.05). The wound infection probability in patients with high post-PTs was 1.953 times greater than that in patients with low post-PTs (OR = 1.953, 95% CI: 1.232 ∼ 3.095, P = 0.004). A normal or overweight BMI was a protective factor for pulmonary infection, and the incidence of pulmonary infection in these patients was only 0.089 times that of patients with a low BMI (OR = 0.089, 95% CI: 0.017 ∼ 0.462). Moreover, a high ASA grade promoted the occurrence of pulmonary infection (OR = 6.373, 95% CI: 1.681 ∼ 24.163). The blood transfusion mode (B = 0.310, ß = 0.360, P < 0.001; ANH: ln hospital stay = 2.20 ± 0.37; ABT: ln hospital stay = 2.54 ± 0.42) improved the length of hospital stay. CONCLUSION: Preoperative and postoperative blood transfusion (Δ) Hb, (Δ) PT, and (Δ) FIB did not differ; (Δ) WBC, (Δ) PLT, (Δ) APTT, and (Δ) D-dimer did differ. There was no difference in the effects of the two blood transfusion methods on flap crisis, incision infection or lung infection after flap reconstruction, but ANH resulted in a 3.65 day shorter average hospital stay than did ABT.

Fluid distribution during surgery in the flat recumbent, Trendelenburg, and the reverse Trendelenburg body positions.

BACKGROUND: The distribution and elimination of infused crystalloid fluid is known to be affected by general anesthesia, but it is unclear whether changes differ depending on whether the patient is operated in the flat recumbent position, the Trendelenburg ("legs up") position, or the reverse Trendelenburg ("head up") position. METHODS: Retrospective data on hemodilution and urine output obtained during and after infusion of 1-2 L of Ringer's solution over 30-60 min were collected from 61 patients undergoing surgery under general anesthesia and 106 volunteers matched with respect to the infusion volume and infusion time. Parameters describing fluid distribution in the anesthetized and awake subjects were compared by population volume kinetic analysis. RESULTS: General anesthesia decreased the rate constant for urine output by 79% (flat recumbent), 91% (legs up) and 91% (head up), suggesting that laparoscopic surgery per se intensified the already strong anesthesia-induced fluid retention. General anesthesia also decreased the rate constant governing the return of the distributed fluid to the plasma by 32%, 15%, and 70%, respectively. These results agree with laboratory data showing a depressive effect of anesthetic drugs on lymphatic pumping, and further suggest that the "legs up" position facilitates lymphatic flow, whereas the "head up" position slows this flow. Both Trendelenburg positions increased swelling of the "third fluid space". CONCLUSIONS: General anesthesia caused retention of infused fluid with preferential distribution to the extravascular space. Both Trendelenburg positions had a modifying influence on the kinetic adaptations that agreed with the gravitational forces inflicted by tilting to body.

Consensus of the Brazilian association of hematology, hemotherapy and cellular therapy on patient blood management: Acute normovolemic hemodilution and intraoperative autotransfusion.

Autologous blood transfusion can be achieved through different techniques, including by the patient donating blood before surgery (pre-deposit), collecting blood from the patient immediately before the operation and replacing the volume with colloids or plasma expanders (acute normovolemic hemodilution) or through the salvage of lost blood, during or immediately after surgery, and its retransfusion after washing (intraoperative or postoperative recovery). We will focus on the two methods used intraoperatively that are of fundamental importance in the management and conservation of the patient's own blood.

Consensus of the Brazilian association of hematology, hemotherapy and cellular therapy on patient blood management: Assessment and management of postoperative anemia.

Postoperative anemia is a complex clinical issue that requires attention due to its ramifications on the patient's recovery and prognosis. Originating from multiple determinants, such as intraoperative blood loss, hemolysis, nutritional deficiencies, systemic inflammation and impact on the bone marrow, postoperative anemia has varied and often challenging presentations. Patients undergoing major surgical procedures, in particular, are susceptible to developing anemia due to the considerable associated blood loss. Accurate diagnosis plays a crucial role in the approach, requiring meticulous hematological analysis, including hemoglobin, hematocrit and reticulocyte count, as well as an in-depth investigation of the underlying causes. An additional challenge arises in the form of the excessive practice of phlebotomy during hospitalization for clinical monitoring. Although it is essential to assess the progression of anemia, frequent removal of blood may contribute to iatrogenic anemia, further delaying recovery and possibly increasing susceptibility to infection.

Evaluating the efficacy of a standardized 4 mL/kg fluid bolus technique in critically ill patients with elevated PvaCO2: secondary analysis of two prospective studies.

Background: Limiting the fluid bolus (FB) volume may attenuate side effects, including hemodilution and increased filling pressures, but it may also reduce hemodynamic responsiveness. The minimum volume to create hemodynamic effects is considered to be 4 mL/kg. In critically ill patients, the hemodynamic effects of FB with this volume have not been adequately investigated and compared to higher quantities. We hypothesized that a standardized FB approach using 4 mL/kg has comparable hemodynamic and metabolic effects to the common practice of physician-determined FB in critically ill patients. Methods: We conducted post hoc analysis of two trials in non-selected critically ill patients with central venous-to-arterial CO2 tension (PvaCO2) >6 mmHg and no acute bleeding. All patients received crystalloids either at a physician-determined volume and rate or at 4 mL/kg pump-administered at 1.2 L/h. Cardiac index (CI) was calculated with transthoracic echocardiogram, and arterial and venous blood gas samples were assessed before and after FB. Endpoints were changes in CI and oxygen delivery (DO2) >15%. Results: A total of 47 patients were eligible for the study, 15 of whom received physician-determined FB and 32 of whom received standardized FB. Patients in the physician-determined FB group received 16 (12-19) mL/kg at a fluid rate of 1.5 (1.5-1.9) L/h, compared to 4.1 (3.7-4.4) mL/kg at a fluid rate of 1.2 (1.2-1.2) L/h (p < 0.01) in the standardized FB group. The difference in CI elevations between the two groups was not statistically significant (8.8% [-0.1-19.9%] vs. 8.4% [0.3-23.2%], p = 0.76). Compared to physician-determined FB, the standardized FB technique had similar probabilities of increasing CI or DO2 by >15% (odds ratios: 1.3 [95% CI: 0.37-5.18], p = 0.66 and 1.83 [95% CI: 0.49-7.85], p = 0.38). Conclusion: A standardized FB protocol (4 mL/kg at 1.2 L/h) effectively reduced the volume of fluid administered to critically ill patients without compromising hemodynamic or metabolic effects.

Accelerated lymph flow from infusion of crystalloid fluid during general anesthesia.

BACKGROUND: Kinetic analysis of crystalloid fluid yields a central distribution volume (Vc) of the same size as the expected plasma volume (approximately 3 L) except during general anesthesia during which Vc might be only half as large. The present study examined whether this difference is due to influence of the intravascular albumin balance. METHODS: A population volume kinetic analysis according to a three-compartment model was performed based on retrospective data from 160 infusion experiments during which 1-2.5 L of crystalloid fluid had been infused intravenously over 20-30 min. The plasma dilution based on blood hemoglobin (Hb) and plasma albumin (Alb) was measured on 2,408 occasions and the urine output on 454 occasions. One-third of the infusions were performed on anesthetized patients while two-thirds were given to awake healthy volunteers. RESULTS: The Hb-Alb dilution difference was four times greater during general anesthesia than in the awake state (+ 0.024 ± 0.060 versus - 0.008 ± 0.050; mean ± SD; P < 0.001) which shows that more albumin entered the plasma than was lost by capillary leakage. The Hb-Alb dilution difference correlated strongly and positively with the kinetic parameters governing the rate of fluid transfer through the fast-exchange interstitial fluid compartment (k12 and k21) and inversely with the size of Vc. Simulations suggest that approximately 200 mL of fluid might be translocated from the interstitial space to the plasma despite ongoing fluid administration. CONCLUSIONS: Pronounced plasma volume expansion early during general anesthesia is associated with a positive intravascular albumin balance that is due to accelerated lymphatic flow. This phenomenon probably represents adjustment of the body fluid volumes to anesthesia-induced vasodilatation.

Exploration of the Clinical Effect of Different Autotransfusion Methods on Patients With Femoral Shaft Fracture Surgery.

OBJECTIVE: To explore the clinical effect of predeposit, salvage, and hemodilution autotransfusion on patients with femoral shaft fracture (FSF) surgery. METHODS: Selected patients with FSF were randomly divided into three groups: intraoperative blood salvage autotransfusion, preoperative hemodilution autohemotransfusion, and predeposit autotransfusion. Five days after the operation, the body temperature, heart rate, blood platelet (PLT), and hemoglobin (Hb) of patients were determined. The concentrations of EPO and GM-CSF in the three groups were calculated by ELISA. The content of CD14+ monocytes was calculated by FCM assay. The growth time and condition of the patient's callus were determined at the 30th, 45th, and 60th day after operation. Cox regression analysis was used to analyze the correlation between EPO, GM-CSF, CD14+ mononuclear content, callus growth, and autotransfusion methods. RESULTS: There were no statistically significant differences in body temperature and heart rate between the three groups (p > 0.05). PLT and Hb in the Predeposit group were markedly increased compared with that in the Salvage and Hemodilution groups. The concentrations of EPO and GM-CSF in the Predeposit group were markedly increased compared with that in the Salvage and Hemodilution groups. The content of CD14+ monocytes in the Predeposit group was significantly higher than that in the Salvage and Hemodilution groups. Predeposit autotransfusion promotes callus growth more quickly. CONCLUSION: Predeposit autotransfusion promoted the recovery of patients with FSF after the operation more quickly than salvage autotransfusion and hemodilution autotransfusion.

Consensus of the Brazilian association of hematology, hemotherapy and cellular therapy on patient blood management: Implementation of Patient Blood Management (PBM).

Patient Blood Management (PBM) is a holistic approach to managing blood as a resource of each patient; it is a multimodal strategy that is implemented using a set of techniques that can be applied in individual cases. In fact, the overall result of the implementation of PBM cannot be fully appreciated or explained by simply summing up the effects of the individual strategies and techniques used, since they can only produce the expected ideal result if combined. Implementing a PBM program in healthcare offers several benefits including improved patient safety, better outcomes, cost savings, conservation of resources, evidence-based practice, transfusion alternatives, improved quality of care, compliance with accreditation standards, patient-centered care, and professional education and training.

Low-Volume Acute Normovolemic Hemodilution Does Not Reduce Allogeneic Red Blood Cell Transfusion in Cardiac Surgery in the Modern Era of Patient Blood Management: A Propensity Score-Matched Cohort Study.

OBJECTIVES: Patients undergoing cardiac surgery often require blood transfusions, which are associated with increased morbidity and mortality. Patient blood management (PBM) strategies, including acute normovolemic hemodilution (ANH), have been implemented to minimize allogeneic transfusion requirements. Older studies suggested that ANH is associated with reduced transfusions; however, its effectiveness in the modern era of PBM remains unclear. DESIGN: This was a retrospective cohort study. SETTING: The study was held at a single university hospital. PARTICIPANTS: 542 patients who underwent elective cardiac surgery with cardiopulmonary bypass (CPB) using low-priming-volume circuits between January 2017 and March 2022. INTERVENTIONS: Patients who received ANH were matched with those who did not receive ANH, using propensity scores. MEASUREMENTS AND MAIN RESULTS: The primary outcome was the proportion of patients who received perioperative red blood cell (RBC) transfusion. Of the 542 eligible patients, 49 ANH cases were propensity-score matched to 97 controls. The median ANH volume was 450 mL (IQR, 400-800 mL). There was no significant difference in perioperative RBC transfusion rates between the 2 groups (24.5% in the ANH group vs 30.9% in the control group, p = 0.42). The odds ratio for perioperative RBC transfusion in the ANH group versus the control group was 0.72 (95% CI, 0.32-1.55, p = 0.42). CONCLUSIONS: Low-volume ANH was not associated with a significant reduction in perioperative allogeneic RBC transfusion during cardiac surgery with CPB using low-priming-volume circuits. The benefits of low-volume ANH in reducing the requirement for RBC transfusion in the modern era of PBM may be smaller than reported previously.

Consensus of the Brazilian association of hematology, hemotherapy and cellular therapy on patient blood management: Acute normovolemic hemodilution and intraoperative autotransfusion

Abstract Autologous blood transfusion can be achieved through different techniques, including by the patient donating blood before surgery (pre-deposit), collecting blood from the patient immediately before the operation and replacing the volume with colloids or plasma expanders (acute normovolemic hemodilution) or through the salvage of lost blood, during or immediately after surgery, and its retransfusion after washing (intraoperative or postoperative recovery). We will focus on the two methods used intraoperatively that are of fundamental importance in the management and conservation of the patient's own blood.

Consensus of the Brazilian association of hematology, hemotherapy and cellular therapy on patient blood management: Assessment and management of postoperative anemia

Abstract Postoperative anemia is a complex clinical issue that requires attention due to its ramifications on the patient's recovery and prognosis. Originating from multiple determinants, such as intraoperative blood loss, hemolysis, nutritional deficiencies, systemic inflammation and impact on the bone marrow, postoperative anemia has varied and often challenging presentations. Patients undergoing major surgical procedures, in particular, are susceptible to developing anemia due to the considerable associated blood loss. Accurate diagnosis plays a crucial role in the approach, requiring meticulous hematological analysis, including hemoglobin, hematocrit and reticulocyte count, as well as an in-depth investigation of the underlying causes. An additional challenge arises in the form of the excessive practice of phlebotomy during hospitalization for clinical monitoring. Although it is essential to assess the progression of anemia, frequent removal of blood may contribute to iatrogenic anemia, further delaying recovery and possibly increasing susceptibility to infection.

Maldistribution of fluid in preeclampsia: a secondary kinetic analysis.

BACKGROUND: Hypovolemia and peripheral edema are frequent components of preeclampsia. The level of the dysregulation of the body fluid distribution is unclear, which complicates the choice of infusion fluid during surgery. The present fluid kinetic study challenges whether the maldistribution of fluid is due to increased capillary leakage or to poor return of already distributed fluid, which occurs via lymphatic pathways. METHODS: Ringers solution was infused in 10 awake non-pregnant women, eight healthy pregnant women, and in eight women with mild-to-moderately severe preeclampsia. Distribution and redistribution of the infused fluid was calculated with mixed models kinetics based on the excreted urine volumes and 675 measurements of hemodilution. Differences in fluid kinetics between the three groups were studied with covariance analysis. RESULTS: The return flow of fluid volume to the plasma after distribution (rate parameter k21) was almost zero in women with preeclampsia, while the rate was normal in the other two groups (P< 0.001). By contrast, the capillary leakage rate of fluid in response to the infusion (k12) was normal. The urinary excretion (k10) was moderately accelerated. CONCLUSION: Decreased flow of extravascular fluid to the plasma was the key disturbance in women with preeclampsia. Such decreased flow alone promotes hypovolemia, peripheral edema, and hypoalbuminemia, and may be explained by inhibition of lymphatic pumping and/or a decreased interstitial hydrostatic pressure due to the presence of vasoactive and inflammatory signal molecules. The moderately accelerated urine flow may be due to "pressure diuresis" in response to hypertension.

Plasma Volume Oscillations during Fluid Therapy in Humans.

INTRODUCTION: Oscillations are frequently observed on plasma dilution curves during intravenous fluid therapy. This study aimed to examine how common these oscillations are and what they represent. METHODS: Fourier transforms were used to analyze the residuals obtained during fitting of a volume kinetic model to 269 plasma dilution curves. Oscillating patterns were identified in two-thirds of the fluid infusion experiments. RESULTS: The wave frequency usually had a dominating frequency of 1 h or multiples thereof. The wave amplitudes varied between 1% and 4% of the plasma volume. The "peak-to-peak" amplitudes were then twice as large, which corresponded to blood volume changes of 60-240 mL. A population kinetic analysis of the distribution of infused fluid between body fluid compartments was then applied to search for clues that could explain the oscillations. This analysis showed that amplitudes >1.5% were associated with doubled turnover of fluid in a fast-exchange interstitial fluid compartment and, together with data on plasma albumin, suggested that oscillations might represent bursts of efferent lymph. CONCLUSIONS: Oscillations with very low frequency were often observed on plasma dilution-time curves obtained during fluid therapy. They were associated with fast turnover of interstitial fluid and can possibly have resulted from accelerated lymphatic flow.

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.

Evidence of serial connection between the plasma volume and two interstitial fluid compartments.

BACKGROUND: Kinetic analysis of fluid volume shifts can identify two interstitial fluid compartments with different turnover rates, but how they are connected to the bloodstream is unknown. METHODS: Retrospective data were retrieved from 217 experiments where 1.5 L of Ringer's solution (mean) had been administered by intravenous infusion over 30 min to awake and anesthetized humans (mean age 40 years). Urinary excretion and hemoglobin-derived plasma dilution served as input variables in a volume kinetic analysis using mixed models software. Possible modes of connection between the two interstitial fluid compartments and the bloodstream were judged by covariance analysis between kinetic rate constants, physiological variables, and time factors. RESULTS: The return flow of already distributed fluid to the plasma via a fast-exchange interstitial compartment was inhibited ongoing infusion of fluid (-38 %), which was probably due to increase of the venous pressure during volume loading. Ongoing infusion also greatly retarded the entrance of fluid to the slow-exchange compartment (-85 %), which suggests that infused Ringer's first had to enter the fast-exchange compartment. A high mean arterial pressure markedly increased the urine output and, to a lesser degree, also the rate of entrance of fluid to the fast-exchange compartment. Moreover, a high blood hemoglobin concentration retarded the rate of entrance of fluid to the fast-exchange compartment. CONCLUSIONS: The fast-exchange but not the slow-exchange interstitial fluid compartment was affected by intravascular events, which suggests that only the fast-exchange compartment is directly connected to the circulating blood.

Comparing acute normovolumic hemodilution with autologous platelet-rich plasma for blood preservation during aortic surgery : study protocol for a randomized controlled clinical trial.

BACKGROUND: Both acute normovolumic hemodilution (ANH) and autologous platelet-rich plasma (aPRP) have been demonstrated blood-protective effects in cardiac aortic surgery; however, the efficacies of the two methods have not been compared. This study aims to compare the effects of aPRP and ANH prior to aortic surgery on postoperative bleed and other outcomes. METHODS AND ANALYSIS: This is a prospective, single-center, double-blind controlled clinical trial including 160 patients randomized 1:1 to receive aPRP (test group) or autologous whole blood (ANH, control group). The primary objective is to compare the drainage volumes in the two groups at 24, 48, and 72 h postoperatively. Secondary outcomes include input of allogeneic blood and blood products and durations of aortic block, extracorporeal circulation, deep hypothermic arrest of circulation, tracheal extubation, hospital stay, requirement for secondary surgical hemostasis, and application of intra-aortic balloon pump or extracorporeal membrane oxygenation in the two groups. In addition, heart rate, systolic blood pressure, diastolic blood pressure, central venous pressure, and thromboelastography recorded before blood reservation (T1), after blood reservation (T2), before blood transfusion (T3), and after the blood is returned (T4) to the transfusion will be compared between the two groups of patients. DISCUSSION: This study will demonstrate if the use of aPRP could reduce the risk of bleeding after aortic surgery compared with ANH. The results are expected to have practical clinical applications in terms of more effective blood protection and shorter hospital stay. TRIAL REGISTRATION: This study was registered with the Chinese Clinical Trial Registry ( http://www.chictr.org.cn/ ) with the ID ChiCTR 1900023351.Registered on May 23, 2019. TRIAL STATUS: Recruiting start date: July 1, 2019; expected recruiting end date: July 1, 2024 Version number and date: Version 2 of 05-04-2019.