Limited intentional normovolemic hemodilution: ST-segment changes and use of homologous blood products in patients with left main coronary artery stenosis

Effect of acute normovolemic hemodilution on coronary artery bypass grafting: A systematic review and meta-analysis of 22 randomized trials

BACKGROUND

Efficacy of minimal acute normovolemic hemodilution (ANH) in avoiding homologous blood transfusion during cardiovascular surgery remains controversial. Postoperative bleeding and transfusion remain a source of morbidity and cost after open heart operations. To better understand the role of acute normovolemic hemodilution (ANH) in coronary artery bypass grafting (CABG), we compared ANH with standard intraoperative care in a systematic review including a standard pairwise meta-analysis of randomized controlled trials (RCTs).

METHODS

We searched the Cochrane Library, PubMed, EMBASE, Web of Science and Chinese National Knowledge Infrastructure (CNKI) up to April 1, 2020. The primary outcome was to assess the incidence of ANH-related number of allogeneic red blood cell units (ARBCu) transfused. Secondary outcomes included the rate of allogeneic blood transfusion and estimated total blood loss.

RESULTS

A total of 22 RCTs including 1688 patients were identified for the present meta-analysis. Of these studies, 19 were about CABG with on-pump and three with off-pump. Our pooled result indicated that patients received ANH experienced fewer ARBCu transfusions, with a standardized mean difference (SMD) of -0.60 (95%CI -0.96 to -0.24; P = 0.001). The rate of allogeneic blood transfusion in ANH group was significant reduced when compared with controls, with a relative risk (RR) of 0.65 (95%CI 0.52 to 0.82; P = 0.0002). In addition, less postoperative estimated total blood loss was present, with a SMD of -0.53 (95%CI -0.88 to -0.17; P = 0.004).

CONCLUSIONS

The present meta-analysis indicated that ANH could reduce the number of ARBCu transfused in the CABG surgery setting. In addition, ANH could also reduce the rate of ARBCu transfusion and estimated total blood loss for CABG patients.

The Safety and Efficacy of “Bloodless” Cardiac Surgery

Nearly 20% of blood transfusions in the United States are associated with cardiac surgery. Despite the many blood conservation techniques that are available, safe, and efficacious for patients undergoing cardiac surgery, many of these operations continue to be associated with significant amounts of blood transfusion. Although surgical bleeding after cardiopulmonary bypass is a common problem as reflected by the substantial use of blood products, it is the individual physician and institutional behavior that have been identified as reasons for transfusion and not necessarily patient comorbidity or blood loss. Transfusion rates in cardiac surgery remain high despite major advances in perioperative blood conservation, with large variations among individual centers. The adoption of available blood conservation techniques, either alone or in combination in patients undergoing cardiac surgery, could result in an estimated 75% reduction of unnecessary transfusions. The success of previously reported blood conservations programs in cardiac surgery should call for a reevaluation of allogeneic transfusion practices in patients undergoing cardiac surgery. By applying the numerous reported blood conservation strategies for the management of patients presenting for cardiac surgery, we can preserve our dwindling blood resources and help alleviate some of the direct costs of blood as well as the indirect costs of treating noninfectious and infectious complications of transfusion.

Transfusion triggers for guiding RBC transfusion for cardiovascular surgery: a systematic review and meta-analysis*

OBJECTIVE

Restrictive red cell transfusion is recommended to minimize risk associated with exposure to allogeneic blood. However, perioperative anemia is an independent risk factor for adverse outcomes after cardiovascular surgery. The purpose of this systematic review and meta-analysis is to determine whether perioperative restrictive transfusion thresholds are associated with inferior clinical outcomes in randomized trials of cardiovascular surgery patients.

DATA SOURCES

The Cochrane Central Register of Controlled Trials, MEDLINE, and EMBASE from inception to October 2013; reference lists of published guidelines, reviews, and associated articles, as well as conference proceedings. No language restrictions were applied.

STUDY SELECTION

We included controlled trials in which adult patients undergoing cardiac or vascular surgery were randomized to different transfusion thresholds, described as a hemoglobin or hematocrit level below which RBCs were transfused.

DATA EXTRACTION

Two authors independently extracted data from included trials. We pooled risk ratios of dichotomous outcomes and mean differences of continuous outcomes across trials using random-effects models.

DATA SYNTHESIS

Seven studies (enrolling 1,262 participants) met inclusion criteria with restrictive and liberal transfusion thresholds most commonly differing by a hemoglobin of 1 g/dL or hematocrit of 6-7%, resulting in decreased transfusions by 0.71 units of RBCs (95% CI, 0.31-1.09, p = 0.0002) without an associated change in adverse events: mortality (risk ratio, 1.12; 95% CI, 0.65-1.95; p = 0.60), myocardial infarction (risk ratio, 0.94; 95% CI, 0.30-2.99; p = 0.92), stroke (risk ratio, 1.15; 95% CI, 0.57-2.32; p = 0.70), acute renal failure (risk ratio, 0.98; 95% CI, 0.64-1.49; p = 0.91), infections (risk ratio, 1.23; 95% CI, 0.85-1.78; p = 0.27), or length of stay. There was no between-trial heterogeneity for any pooled analysis. Including four pediatric trials (456 participants) and 10 trials utilizing only intraoperative acute normovolemic hemodilution (872 participants) did not substantially change the results except that unlike the transfusion threshold trials, the hemodilution trials did not reduce the proportion of patients transfused (interaction p = 0.01).

CONCLUSIONS

Further randomized controlled trials are necessary to determine the optimal transfusion strategy for patients undergoing cardiovascular surgery.

Burden of blood transfusion in knee and hip surgery in the US and Belgium

OBJECTIVE

Transfusion services in orthopaedic surgery can lead to unnecessary complications and increased healthcare costs. The objective of this study was to assess treatments and costs associated with blood and blood product transfusions in a historical cohort of 189,457 inpatients in the US and 34,987 inpatients in Belgium undergoing knee or hip surgery.

METHODS

Descriptive analysis, logistic regression and ordinary least squares regression were used to describe the factors associated with the use and cost of allogeneic blood transfusion.

RESULTS

Hospitalisation costs for joint replacement surgery totalled $12,718 (SD=6,356) and averaged 4.33 days in the US, while costs in Belgium were $6,526 (SD=3,192) and averaged 17.1 days. The use of low molecular weight heparin and tranexamic acid was much higher in Belgium than the US (36% and 99% compared to 0% and 40%, respectively). Patients in the US spent 12.7 (p<0.0001) fewer days in the hospital, 0.3 (p<0.0001) fewer days in the intensive care unit and were 88% less likely to have allogeneic blood transfusions (OR=0.22, 95% CI 0.22-0.23), but incurred $6,483 (p<0.0001) more costs per hospitalisation than patients in Belgium.

CONCLUSIONS

While hospital costs for patients were greater in the US, length of stay was shorter and patients were less likely to have transfusion services than those patients in Belgium. While this study is limited by factors inherent to observational studies, such as omitted variable bias, misclassification, and disease comorbidity, there are substantial differences in the use of blood products between Belgium and the US.

Comparison between spinal surgery blood transfusion services costs and associated treatment practices in the United States and Belgium

OBJECTIVE

This study assessed utilization and cost of allogeneic blood transfusion (ABT) associated with spinal surgery in the United States (US) and Belgium.

METHODS

A retrospective cohort of 292,864 spinal surgery inpatients in US hospitals was pooled with a cohort of 27,952 inpatients who had similar procedures in Belgian hospitals. Utilization and cost data were derived from hospital accounting systems. Costs were converted to US dollars. Descriptive and multivariate statistics were used to describe the factors associated with the use and cost of ABT. Missing data, confounding, and variable measurement error were addressed using standard approaches for observational studies.

RESULTS

US hospitalizations cost $12,044 (SD = 15,920) over 3.6 days compared to $4010 (SD = 3586) over 10.3 days in Belgium. Low molecular weight heparin was used by 78% of Belgian patients and 4% of US patients. Red blood cell utilization occurred in approximately 7% of patients from both countries; however US patients received 6 units compared to 3 units by Belgian patients. US patients spent 3.5 (p < 0.0001) less days in hospital, 1.0 (p < 0.0001) more days in an intensive care unit, used 64% more allogeneic blood (OR = 1.64, 95% CI 1.53-1.75), and incurred $13,647 (p < 0.0001) more per hospitalization than Belgian patients.

CONCLUSIONS

US patients used more blood products, had shorter hospital stays, and incurred greater costs than Belgian patients. Specialists as attending physicians were associated with lower utilization of ABT; this may be an administrative change that hospitals can implement to reduce utilization and costs.

State-of-the-art blood saving techniques

Preoperative autologous donation, the use of erythropoietin, acute normovolaemic haemodilution, acceptance of minimal perioperative haemoglobin levels, the use of specific drugs (aprotinin, antifibrinolytics), cell saving and a meticulous surgical technique aimed at minimizing blood loss have all been described as blood saving techniques. Each has proved effective in reducing the need for allogeneic blood transfusions. With an appropriate selection of patients, all techniques can be used efficiently.

The Effect of Gain in Total Body Water on Haemoglobin Concentration and Body Weight Following Cardiac Surgery

BACKGROUND

Haemodilution contributes to a low post-operative haemoglobin concentration in cardiac surgery patients. An assessment of the degree of haemodilution could contribute to the avoidance of red cell transfusion when such an act is based simply on a haemoglobin "transfusion trigger". We have recorded post-operative change in total body water along with body weight to assess the impact of haemodilution on haemoglobin concentration.

METHODS

Total body water, measured by bio-electrical impedance analysis, haemoglobin and body weight were measured pre-operatively and on the 1st, 3rd, 5th and 10th post-operative days. The percentage peri-operative change in all three variables was used to examine the paired associations.

RESULTS

Total body water and body weight underwent a fall from day 1, with both variables significantly associated up until day 10. Haemoglobin rose steadily from day 1 to 10. This rise was associated with falling total body water and body weight until day 5, but not from day 5 to 10.

CONCLUSION

Following cardiac surgery, an individual's fluid state should be considered in determining a patient's need for red cell transfusion. Monitoring body weight provides a simple estimate. Such an approach may reduce the incidence of unnecessary, and potentially counterproductive, transfusion in cardiac surgery patients.

Orthogonal search-based rule extraction for modelling the decision to transfuse

Data from an audit relating to transfusion decisions during intermediate or major surgery were analysed to determine the strengths of certain factors in the decision making process. The analysis, using orthogonal search-based rule extraction (OSRE) from a trained neural network, demonstrated that the risk of tissue hypoxia (ROTH) assessed using a 100-mm visual analogue scale, the haemoglobin value (Hb) and the presence or absence of on-going haemorrhage (OGH) were able to reproduce the transfusion decisions with a joint specificity of 0.96 and sensitivity of 0.93 and a positive predictive value of 0.9. The rules indicating transfusion were: 1. ROTH > 32 mm and Hb < 94 g x l(-1); 2. ROTH > 13 mm and Hb < 87 g x l(-1); 3. ROTH > 38 mm, Hb < 102 g x l(-1) and OGH; 4. Hb < 78 g x l(-1).

Cost and utilization of blood transfusion associated with spinal surgeries in the United States

The purpose of this study was to examine factors associated with the utilization and cost of blood transfusion during and post-spinal fusion surgery. A retrospective, observational study of 42,029 inpatients undergoing spinal fusion surgery in United States hospitals participating in the Perspective( Comparative Database for inpatient use was conducted. Descriptive analysis, logistic regression, and ordinary least squares (OLS) regression were used to describe the factors associated with the use and cost of allogeneic blood transfusion (ABT). Hospitalization costs were $18,690 (SD=14,159) per patient, erythropoietin costs were $85.25 (SD=3,691.66) per patient, and topical sealant costs were $414.34 (SD=1,020.06) per patient. Sub-analysis of ABT restricted to users revealed ABT costs ranged from $312.24 (SD=543.35) per patient with whole blood to $2,520 (SD=3,033.49) per patient with fresh frozen plasma. Patients that received hypotensive anesthesia (OR,1.61; 95% CI, 1.47-1.77), a volume expander (OR,1.95; 95% CI, 1.75-2.18), autologous blood (OR, 2.04; 95% CI, 1.71-2.42), or an erythropoietic agent (OR=1.64; 95% CI, 1.27-2.12) had a higher risk of ABT. Patients that received cell salvage had a lower risk of transfusion (OR=0.40; 95% CI, 0.32-0.50). Most blood avoidance techniques have low utilization or do not reduce the burden of transfusion associated with spinal fusion.

Resource utilization and costs of blood management services associated with knee and hip surgeries in US hospitals

This article assesses the use and costs of blood transfusion during knee and hip surgery through a retrospective observational study of 92,223 discharged inpatients who had undergone knee or hip surgery from July 1, 2003, through June 30, 2004; a sample of US hospitals that participated in the Perspective Comparative Database (Premier Inc., Charlotte, NC) was used. Descriptive and multivariate analyses were performed to determine the use and costs of allogeneic blood transfusion (ABT). The average cost of ABT per user ranged from $387 (SD=$952) for red blood cells to $6585 (SD=$11,162) for cryoprecipitate. Utilization rates in the sample were as follows: antifibrinolytics, 0.14%; topical sealants, 3.24%; volume expanders, 3.89%; erythropoietin agents, 5.08%; and hypotensive anesthesia, 22.28%. Patients who were given volume expanders ($133.73, SD=$23.00, P<.01) or erythropoietin ($177.72, SD=$34.61, P<.01) had higher costs associated with ABT than did those who did not use volume expanders or erythropoietin. Patients who received hypotensive anesthesia (odds ratio [OR]=1.96; 95% confidence interval [CI], 1.87-2.06), a volume expander (OR=1.71; 95% CI, 1.57- 1.85), a topical sealant (OR=1.61; 95% CI, 1.45-1.79), or an erythropoietic agent (OR=2.30; 95% CI, 2.06-2.57) had a greater likelihood of ABT. Investigators concluded that most transfusion reduction techniques are underused, or they do not reduce the burden of ABT associated with knee or hip surgery.

Cardiovascular response to acute normovolemic hemodilution in patients with coronary artery diseases: Assessment with transesophageal echocardiography

OBJECTIVE

Preoperative acute normovolemic hemodilution induces an increase in circulatory output that is thought to be limited in patients with cardiac diseases. Using multiple-plane transesophageal echocardiography, we investigated the mechanisms of cardiovascular adaptation during acute normovolemic hemodilution in patients with severe coronary artery disease.

DESIGN

Prospective case-control study.

SETTING

Operating theater in a university hospital.

PATIENTS

Consecutive patients treated with beta-blockers, scheduled to undergo coronary artery bypass (n = 50).

INTERVENTIONS

After anesthesia induction, blood withdrawal and isovolemic exchange with iso-oncotic starch (1:1.15 ratio) to achieve a hematocrit value of 28%.

MEASUREMENTS AND MAIN RESULTS

In addition to heart rate and intravascular pressures, echocardiographic recordings were obtained before and after acute normovolemic hemodilution to assess cardiac preload, afterload, and contractility. In a control group, not subjected to acute normovolemic hemodilution, hemodynamic variables remained stable during a 20-min anesthesia period. Following acute normovolemic hemodilution, increases in cardiac stroke volume (+28 +/- 4%; mean +/- sd) were correlated with increases in central venous pressure (+2.0 +/- 1.3 mm Hg; R = .56) and in left ventricular end-diastolic area (+18 +/- 5%, R = .39). The unchanged left ventricular end-systolic wall stress and preload-adjusted maximal power indicated that neither left ventricular afterload nor contractility was affected by acute normovolemic hemodilution. Diastolic left ventricular filling abnormalities (15 of 22 cases) improved in 11 patients and were stable in the remaining four patients. Despite reduction in systemic oxygen delivery (-20.5 +/- 7%, p < .05), there was no evidence for myocardial ischemia (electrocardiogram, left ventricular wall motion abnormalities).

CONCLUSIONS

In anesthetized patients with coronary artery disease, moderate acute normovolemic hemodilution did not compromise left ventricular systolic and diastolic function. Lowering blood viscosity resulted in increased stroke volume that was mainly related to increased venous return and higher cardiac preload.

Prospective randomized controlled trial of acute normovolaemic haemodilution in major gastrointestinal surgery

BACKGROUND

The efficacy of acute normovolaemic haemodilution (ANH) remains uncertain because of a lack of well-designed prospective randomized controlled trials. The aim of this study was to assess the effects of ANH on allogeneic transfusion, postoperative complications, and duration of stay.

METHODS

Consecutive patients undergoing major gastrointestinal surgery were randomized to a planned 3-unit ANH, or no ANH. Both groups underwent identical management including adherence to a transfusion protocol after surgery. Outcome measures included the number of patients receiving allogeneic blood, complications, and duration of stay.

RESULTS

380 patients were screened of which 160 were included in the study, median age was 62 yr (range 23-90), 'ANH' n=78, 'no ANH' n=82. There was no significant difference between groups in the number of patients receiving allogeneic blood 22/78 (28%) vs 25/82 (30%), the total number of allogeneic units transfused (90 vs 93), complication rate, or duration of stay. Haemodilution significantly increased anaesthetic time, median 55 (range 15-90) vs 40 min (range 17-80) (P<0.001). Significantly fewer patients in the ANH group experienced oliguria in the immediate postoperative period 37/78 (47%) vs 55/82 (67%) (P=0.012). The most significant factors affecting transfusion were blood loss, starting haemoglobin, and age. When compared with ASA-matched historical controls, the introduction of a transfusion protocol reduced the transfusion rate in colorectal patients from 136/333 (41%) to 37/138 (27%), P=0.004.

CONCLUSIONS

In this large pragmatic study, ANH did not affect allogeneic transfusion rate in major gastrointestinal surgery. Preoperative haemoglobin, blood loss, and transfusion protocol are the key factors influencing allogeneic transfusion.

Preoperative acute normovolemic hemodilution: a meta-analysis

BACKGROUND

Acute normovolemic hemodilution (ANH) involves withdrawal of whole blood with concurrent infusion of fluids to maintain normovolemia. The aim of this study was to quantify the efficacy and safety of preoperative ANH with a systematic review and meta-analysis.

STUDY DESIGN AND METHODS

Randomized controlled trials were identified through MEDLINE (1966-2002) and the Cochrane Controlled Trials Database and with hand searching of journals. All trials of preoperative ANH reporting on allogeneic transfusion, bleeding, or adverse outcomes were included. Paired reviewers independently abstracted data. Outcomes were pooled using random-effects models.

RESULTS

A total of 42 trials compared hemodilution to usual care or to another blood conservation method. The risk of allogeneic transfusion was similar among patients receiving ANH and those receiving usual care (relative risk [RR], 0.96; 95% CI, 0.90-1.01), or another blood conservation method (RR, 1.11; 95% CI, 0.96-1.28). Hemodiluted patients, however, were transfused from 1 to 2 fewer units of allogeneic blood. They had less total bleeding than patients receiving usual care (91 mL; 95% CI, 25-158 mL), although more intraoperative bleeding. Only one-third of studies reported on adverse events.

CONCLUSIONS

The literature supports only modest benefits from preoperative ANH. The safety of the procedure is unproven. Widespread adoption of ANH cannot be encouraged.

Predictors of transfusion requirements for cardiac surgical procedures at a blood conservation center

BACKGROUND

Previous studies defining perioperative risk factors for allogeneic transfusion requirements in cardiac surgery were limited to highly selected cardiac surgery populations or were associated with high transfusion rates. The purpose of this study was to determine perioperative risk factors and create a formula to predict transfusion requirements for major cardiac surgical procedures in a center that practices a multimodality approach to blood conservation.

METHODS

We performed an observational study on 307 consecutive patients undergoing coronary artery bypass grafting, valve, and combined (coronary artery bypass grafting and valve) procedures. An equation was derived to estimate the risk of transfusion based on preoperative risk factors using multivariate analysis. In patients with a calculated probability of transfusion of at least 5%, intraoperative predictors of transfusion were identified by multivariate analysis.

RESULTS

Thirty-five patients (11%) required intraoperative or postoperative allogeneic transfusions. Preoperative factors as independent predictors for transfusions included red blood cell mass, type of operation, urgency of operation, number of diseased vessels, serum creatinine of at least 1.3 mg/dL, and preoperative prothrombin time. Intraoperative factors included cardiopulmonary bypass time, three or fewer bypass grafts, lesser volume of acute normovolemic hemodilution removed, and total crystalloid infusion of at least 2,500 mL. The derived formula was applied to a validation cohort of 246 patients, and the observed transfusion rates conformed well to the predicted risks.

CONCLUSIONS

A multimodality approach to blood conservation in cardiac surgery resulted in a low transfusion rate. Identifying patients' risks for transfusion should alter patient management perioperatively to decrease their transfusion rate and make more efficient use of blood resources.

Autologous versus allogeneic transfusion in aortic surgery: a multicenter randomized clinical trial

OBJECTIVE

To evaluate the efficacy of acute normovolemic hemodilution (ANH) and intraoperative cell salvage (ICS) in blood-conservation strategies for infrarenal aortic surgery.

SUMMARY BACKGROUND DATA

Recent concerns over the risks of transfusion-related infection have resulted in sharp rises in the cost of blood preparations. Autologous transfusion may be a safe alternative to allogeneic transfusion, which has been associated with immune modulation and postoperative infection.

METHODS

This multicenter prospective randomized trial compared standard transfusion practice with autologous transfusion combining ANH with ICS in 145 patients undergoing elective aortic surgery. The primary outcome measures were the proportion of patients requiring allogeneic blood and the volume of allogeneic transfusion. The secondary outcome measures were the frequency of complications, including postoperative infection, and postoperative hospital stay.

RESULTS

The combination of ANH and ICS reduced the volume of allogeneic blood transfused from a median of two units to zero units. The proportion of patients transfused was 56% in allogeneic and 43% in autologous. There were no significant differences in complications or length of hospital stay.

CONCLUSIONS

Both ANH and ICS were safe and reduced the allogeneic blood requirement in patients undergoing elective infrarenal aortic surgery.

Perioperative blood transfusions: indications and options

A reevaluation of the indications for and alternatives to transfusion of allogeneic blood was precipitated by transfusion-induced HIV. The transfusion trigger has shifted from an optimal hemoglobin level and hematocrit (10/30) to that level of hemoglobin necessary to meet the patient's tissue oxygen demands. This critical level can best be determined by physiologic measurements. A number of autologous blood options can reduce the patient's allogeneic blood needs. Pharmacologic measures to increase hemoglobin levels (erythropoietin) and to decrease blood loss at surgery are discussed as are the potential contributions of blood substitutes to transfusion support of the surgical patient.